Induction — Infection & Tropical

Written by Betra Youhanna, a medical student and not a doctor — check every detail against your own teaching.

47 diseases · 18 criteria · structured C/P · Inves · Mng

C/P — Clinical Presentation

Inves — Investigations

Mng — Management

Special — Pathognomonic / disease-unique

Hospital-Acquired & Surgical Infection

21 entries

Surgical Site Infection (SSI)

C/P

Erythematous, oedematous, tender wound; bacterial count >100,000 organisms/g tissue
Most common early post-op fever cause traditionally blamed on atelectasis; SSIs typically present later
20% of surgical patients acquire nosocomial infections; SSI = 3rd most common form
1–12% complication rate across all operations
Operation-specific rates: inguinal herniorrhaphy 2%; cholecystectomy 3%; appendectomy 5%; thoracotomy 6%; colectomy 12%
Early infection (<12h): fever to 39°C, foul-smelling serous discharge, particularly painful wound, ± crepitus — red flag for clostridial infection
Organ/space SSI may remain occult or present only with systemic signs — fever, ileus, shock (mimics incisional SSI)

Inves

Septic screen: blood cultures, FBC + CRP, MSU, aspiration of pus (preferred to swab), CXR
Gram stain of the serous discharge for gram-positive rods — confirms or excludes clostridial infection

Mng

Source control (incision/drainage)
Antibiotics
Remove/change lines
Infection control measures
Antibiotic prophylaxis: give within 1h before incision (2h for vancomycin/fluoroquinolone), redose per drug half-life, stop within 24h (48h for cardiac surgery); clindamycin if β-lactam allergy
Superficial SSI: open the incision + local wound care; antibiotics only if erythema extends beyond the wound margin or systemic signs

Special

Endogenous source (primary): patient's own flora; e.g., perforated appendix
Exogenous source (secondary/HAI): operating theatre or ward
Most common bacterial source in groin hernia repair = patient's skin
Highest predisposed procedures = GI (especially colon opened)
Risk of death 4× higher; cost $12,000–30,000 per infection; LOS +3–7 days
Bacterial translocation can occur in as little as 30 minutes when gut barrier breached
Timing criterion: must occur within 30 days of surgery — or within 1 year if implanted foreign material is present
Depth classification: superficial incisional (skin/subcutaneous), deep incisional (fascial/muscle layers), organ/space (any structure opened or manipulated during the operation)
Wound contamination classes (infection rate): I Clean 2.1%, II Clean-contaminated 3.3%, III Contaminated 6.4%, IV Dirty-infected 7.1%
NNIS risk index: ASA score >2; class III/IV wound; operative duration >75th percentile for that procedure
Foreign material drops the infective inoculum to only 100 bacteria (vs 1 million on violated skin, 8 million on intact skin)

physiology · background · low-yield

Epidemiology/Risk

Cigarette smoking is the leading preventable patient factor — more than triples incisional wound breakdown risk (0.6%→3.6% in clean procedures)
Perioperative normothermia markedly reduces SSI: 19% wound infection in hypothermic vs 6% normothermic colorectal patients; blood transfusion increases risk (immunosuppression)

Mechanism

The 'decisive period': host inflammatory/humoral/cellular defenses take up to 4h to mobilise — antibiotic tissue levels must exceed MIC90 before incision or prophylaxis is ineffective

Background

Wound irrigation: tap water reduces bacterial load; alcohol, sodium hypochlorite and hydrogen peroxide are toxic to tissue/fibroblasts — 'put nothing into a wound you would not put in your eye'
Preventive measures: hair removal with clippers/depilatory not razors; intranasal mupirocin for S. aureus nasal carriers; oral + IV antibiotics superior to IV alone in elective colon surgery
Vacuum-assisted closure (VAC) optimises blood flow, reduces oedema and aspirates fluid — but can mask wound sepsis (odour/drainage hidden by suction apparatus)

Ventilator-Associated Pneumonia (VAP) / HAP / HCAP

C/P

VAP: pneumonia occurring 48–72h after endotracheal intubation
Most common ICU infection for surgical/trauma patients
Early-onset VAP (<5 days): trauma patients prone; aspiration of gastric contents
Late-onset VAP (≥5 days): MDR pathogens

Inves

Culture-guided
Cover gram-positive cocci more common in diabetics, head trauma, ICU

Mng

Early broad-spectrum antibiotics in adequate doses; deescalate based on culture
Delayed appropriate therapy → increased mortality
Empirical (immunocompetent, no MDR risk): ceftriaxone, fluoroquinolone, ampicillin/sulbactam, ertapenem
MRSA: linezolid (with emerging linezolid resistance)
P. aeruginosa: some isolates only susceptible to polymyxin B

Special

VAP partly iatrogenic
Early-onset organisms: methicillin-sensitive S. aureus, Streptococcus pneumoniae, Haemophilus influenzae (usually sensitive)
Late-onset MDR organisms: MRSA, Pseudomonas aeruginosa, Acinetobacter spp.
Common gram-negatives: P. aeruginosa, E. coli, K. pneumoniae, Acinetobacter
Anaerobic infection follows aspiration in non-intubated patients; rare in VAP
Candida in immunocompetent patient = colonisation, not infection
MDR risk factors: hospitalisation ≥5 days; antimicrobials/hospitalisation in prior 90d; nursing home; home infusion; chronic dialysis within 30d; home wound care; family member with MDR pathogen; immunosuppression
Pneumonia is 2nd most common nosocomial infection after UTI
Early-onset VAP carries a better prognosis than late-onset
P. aeruginosa is the most common gram-negative pathogen in MDR HAP/VAP; some isolates susceptible only to polymyxin B

physiology · background · low-yield

Epidemiology/Risk

S. aureus accounts for ~40% of VAP episodes and most cases of nosocomial pneumonia

Microbiology

Pathogens are a wide spectrum, often polymicrobial (especially in ARDS patients)

Mechanism

Broad-spectrum antibiotics replace upper-respiratory-tract commensals with Klebsiella, which then causes VAP

Post-operative UTI (Catheter-associated)

C/P

Most patients harbour infected urine by 5–7 days after surgery (longer catheter = more likely)
One of the "4 Ws" of post-op fever ("Water")
Urinary catheter left >2 weeks often causes infection; catheters beyond a few days need increased UTI surveillance

Inves

Urinalysis: WBC
Urine culture: >100,000 bacteria/ml

Mng

Treat per culture
Catheter removal/change

Special

Bacteria crawl up the outside of the urethral catheter
Urological instrumentation accelerates the process
UTI = most common nosocomial infection overall (35% of HAI in pie chart)

Intra-abdominal Infections (IAI)

C/P

Uncomplicated (uIAI): contained within a single organ; no GI perforation; rarely causes serious illness
Complicated (cIAI): extends beyond source organ into peritoneal cavity via perforated viscus → SIRS
Contained spread → abscess; uncontained → diffuse peritonitis → higher mortality, needs urgent celiotomy
CA-IAI (community-acquired): lower mortality/morbidity
HA-IAI (healthcare-associated): higher mortality/morbidity; resistant pathogens; portends particularly poor prognosis
Occult (usually intra-abdominal) abscess is a classic cause of late post-op fever (~2 weeks)
Typically polymicrobial gut flora — Enterobacteriaceae (esp. E. coli), anaerobes (Bacteroides fragilis) and enterococci; empirical cover must include anaerobes + gram-negatives

Inves

Imaging to identify source; cultures

Mng

CA-IAI: narrow-spectrum, pathogen-specific antimicrobial
HA-IAI / high-risk cIAI: broad-spectrum empirical antimicrobial (MDR risk)
Source control (e.g., percutaneous drain by interventional radiology for subphrenic abscess; surgical for perforated viscus)

Special

Delayed diagnosis triad in HA-IAI: low index of suspicion, poor underlying health, altered sensorium
Healthcare-associated nonpostoperative IAI (e.g., acute acalculous/non-calcular cholecystitis in a hospitalised patient) — portends a particularly poor prognosis

C. difficile Colitis

C/P

Frequent stools, abdominal pain, somnolence after recent broad-spectrum antibiotic course
Can progress to septic shock with cool skin, hypotension, elevated lactate

Inves

Stool testing (implied — deck doesn't enumerate specific tests)

Mng

Per institutional protocol; source control
Hand hygiene = soap and water — alcohol gel/hand rub is ineffective against C. difficile spores; use contact isolation

Special

Replaces colonic commensals after broad-spectrum antibiotics
"Potentially life-threatening diarrhoea in postoperative patients"
Classic context: recent antibiotic course (e.g., diverticulitis treatment)

physiology · background · low-yield

Mechanism

Normal gut flora ordinarily discourages C. difficile colonisation; broad-spectrum antibiotics clear commensals and allow overgrowth (also occurs in community and nosocomial settings)

Necrotising Soft Tissue Infections (NSTI)

Inves

Simpler 'Wall' model: admission WBC <15,400/uL and/or serum Na >135 mEq/L gives NPV 99% and 90% sensitivity for NSTI (distinct from the LRINEC score)
Low serum Na theorised to reflect SIADH or adrenal insufficiency

Special

Incidence 0.40 per 100,000 in adults vs 0.08 per 100,000 in paediatrics per year; affects males and females equally
Streptococcus is the #1 isolated organism (then Staphylococcus); Clostridium is now a RARE cause due to improved sanitation; of monomicrobial NSTIs, Klebsiella, S. pyogenes and C. perfringens are most common
Obesity paradox: one study demonstrated a PROTECTIVE effect of obesity on in-hospital mortality in NSTI
Paediatric NSTI: predisposing factors consistently include varicella lesions and intramuscular injections; more likely monomicrobial secondary to Streptococcus pyogenes
Type 2 diabetics presenting in diabetic ketoacidosis have longer hospital stays and higher mortality; poor glycaemic control correlates with extent of disease and poor outcomes

Clostridial Myonecrosis / Gas Gangrene

Mng

Antibiotic differs from necrotizing fasciitis: high-dose penicillin for clostridial infection (vs broad-spectrum for necrotizing fasciitis)
Both need fluid/electrolyte resuscitation plus aggressive debridement

Special

Clostridial infection involves underlying MUSCLE -> myonecrosis / gas gangrene; non-clostridial NSTI involves the subcutaneous fascia

Anthrax (Bacillus anthracis)

Special

Category-A biologic warfare agent selected for inhalational (mass-exposure) spread

Plague (Yersinia pestis)

Special

Named biologic warfare agent (Yersinia pestis)

Smallpox

Special

Named biologic warfare agent

Tularemia (Francisella tularensis)

Special

Named biologic warfare agent (Francisella tularensis)

Wound dehiscence & evisceration

C/P

Dehiscence = partial/total disruption of any/all layers of an operative wound; evisceration = rupture of abdominal wall + extrusion of viscera
Timing: most common 5th-10th postop day (wound strength at its minimum)
First sign = serosanguineous leak; tearing/popping on coughing
Healing ridge normally ~0.5 cm each side within 1 week; its absence predicts breakdown

Mng

Dehiscence: elective reclosure if no infection; otherwise heal by second intention
Evisceration = emergency (mortality 10-20%); cover with moist towels, prompt closure

Special

Adequacy of closure is MOST important; infection is the agent in >half of dehisced wounds
Predisposing: age >60, obesity, raised intra-abdominal pressure, malnutrition, renal/hepatic insufficiency, DM, corticosteroids, cytotoxics, prior irradiation, infection

Vacuum-assisted closure (VAC) / negative pressure wound therapy

Mng

Uses: sternal infection after cardiac surgery, abdominal wall dehiscence, complex perineal wounds, securing skin grafts

Special

First appraised in a porcine model in 1997
Optimizes blood flow, decreases oedema, aspirates fluid (facilitates bacterial clearance); negative pressure promotes wound contraction + may increase cellular proliferation
Odour/drainage clues to wound sepsis are hidden by the suction apparatus - evaluate the wound if sepsis signs appear with an unidentified source

Catheter-related bloodstream infection / bacteraemia

Mng

Prevention: full sterile barrier precautions, strict catheter-care protocols, prompt removal when no longer needed

Special

One of the 4 main HAI groups (mostly related to indwelling vascular catheters)
IV catheter placed in a central vein, in place >3-5 days, or used for blood sampling

Fever - pathophysiology & antipyresis

C/P

Normal core temp 36-38 C (cool ~36 C before rising in the morning, hot ~38 C at night)
Fever = pathologic systemic inflammatory state; core temp >38 C but rarely >40 C

Mng

Antipyresis: aspirin / paracetamol / ibuprofen = COX inhibitors blocking prostaglandin E2 formation in the hypothalamus

Special

Macrophages activated by bacteria/endotoxin release IL-1, TNF and interferon, which reset the hypothalamic thermoregulatory centre
Sterile atelectasis (early postop collapse is typically not infected) has nothing to do with fever; a total pneumothorax (large atelectasis) does NOT cause fever

Sepsis / Septic Shock - hospital aetiology

Special

Aetiology in hospitalised adults has shifted from predominantly gram-negative nosocomial (E. coli, Klebsiella, Enterobacter, Pseudomonas aeruginosa) to gram-positive (S. aureus, S. pneumoniae, S. pyogenes)
Gram-positive sepsis incidence up 26.3% per year since the early 1980s; MDR pathogens (esp S. aureus) now >half of all sepsis cases; S. aureus alone = 40% of VAP episodes + most nosocomial pneumonia
Group B Streptococcus = leading cause of neonatal sepsis in the United States

Surgical Site Infection (SSI) - risk factors & prevention

Mng

Smoking = probably the leading PREVENTABLE patient factor; >triples incisional breakdown, increased SSIs sixfold (0.6% to 3.6%) in clean procedures; decreases wound blood flow/O2 delivery, impedes all stages of healing
Surgical scrub: classic = 3-min brushing with povidone-iodine or chlorhexidine gluconate (high noncompliance); simpler 1-min non-antiseptic soap wash + aqueous alcoholic hand-rub gives better compliance with comparable SSI rates
Hair removal: NO hair removal preferred; if removed use clippers or depilatory immediately before surgery - razors are not to be used
Normothermia: colorectal surgery 19% (hypothermic) vs 6% (kept normothermic); clean surgery (breast/varicose vein/hernia) 5% (warmed 30 min pre-op) vs 14%; target core temp 96.8-100.4 F within first hour after leaving OR
Glucose control (cardiac surgery): keep blood glucose <200 mg/dL for first 2 postop days (measured closest to 6am on days 1 and 2); continuous-infusion control decreases sternal wound infection in diabetics; risk = hypoglycaemia
Other prophylactic routes: intranasal mupirocin ointment in S. aureus nasal carriers may decrease nosocomial + SSI; in elective colon surgery oral + IV antibiotics are superior to IV alone
Wound irrigation: tap water decreases bacterial load + promotes healing; alcohol toxic to tissues; Dakin solution (sodium hypochlorite) + hydrogen peroxide kill fibroblasts and slow epithelialisation ('put nothing in a wound you would not put in your eye')
Blood transfusion increases wound-infection risk (immunosuppressive effect)

Special

The 'decisive period' - acute inflammatory/humoral/cellular defences take up to 4 hours to mobilise; invading bacteria become established in this window, after which preventive strategies are ineffective; tissue levels must exceed the MIC90 of likely pathogens
Each mL of human saliva contains 100,000,000 aerobic + anaerobic, gram-positive + gram-negative bacteria; all human bites are contaminated, whereas animal bites are typically less contaminated
SSI risk factors organised into 5 categories: patient, local, microbial, environmental, treatment
Adequacy of regional blood supply is predictive - evidenced by the low infection rate of facial wounds
Endogenous source: large bowel is a reservoir for bacteria + endotoxin; breach (splanchnic ischaemia, impoverished luminal nutrition of enterocytes, or altered flora) allows translocation into the portal circulation in as little as 30 min; if Kupffer cells are also impaired, bacteria/endotoxin reach the systemic circulation (may explain hepatorenal syndrome in jaundiced surgical patients + the ~30% who develop organ dysfunction with no obvious infection source)

C. difficile colitis / Pseudomembranous colitis

Mng

Oral metronidazole first-line; oral vancomycin second-line

Special

Alcohol gel hand cleansers are ineffective against C. difficile spores - require cleansing with soap and water

Bacterial toxins - exotoxin vs endotoxin

Special

General rule: gram-positive organisms produce EXOTOXINS; gram-negative organisms have ENDOTOXINS
B. fragilis (gram-negative) produces no exotoxin and has defective lipopolysaccharide + lipid A
C. perfringens produces a heat-labile enterotoxin causing watery diarrhoea
S. aureus produces haemolysin + leukocidin (damage plasma membranes) and exfoliatin (cleaves desmosomes)

Antibiotic pharmacology - mechanisms

Special

Beta-lactams (penicillins, cephalosporins, monobactams, carbapenems) inhibit the final step of cell-wall synthesis via transpeptidases / penicillin-binding proteins
Tazobactam / sulbactam / clavulanic acid bind beta-lactamases (Zosyn, Augmentin)
Metronidazole inhibits nucleic-acid synthesis, requires reduction to its active form (anaerobes only), has a disulfiram-like reaction (no alcohol), is liver-cleared, and prolonged use causes peripheral neuropathy
Aminoglycosides + tetracyclines inhibit the 30S ribosome; linezolid / macrolides / chloramphenicol inhibit the 50S; clindamycin (lincosamide) interferes with the amino-acyl-tRNA complex

Nosocomial infection (general)

Special

Increased risk: underlying chronic disease, alteration in host defences, prolonged hospital stay, presence of invasive catheters/monitoring devices
Pulmonary, urinary tract, GI and wound infections predominate

Malaria & Protozoal

4 entries

Malaria

C/P

Initial symptoms non-specific: tachycardia, tachypnea, chills, malaise, fatigue, diaphoresis, headache, cough, anorexia, nausea, vomiting, abdominal pain, diarrhoea, arthralgia, myalgia
Physical: anaemia + palpable spleen
Mild jaundice may develop in uncomplicated falciparum
Febrile paroxysms at irregular intervals; temp can rise >40°C with tachycardia/delirium; cyclic 2–3 days
Febrile convulsions in children (any species); generalised seizures associated with falciparum (may herald cerebral malaria)
Severe malaria: altered consciousness ± seizures; respiratory distress or ARDS; circulatory collapse; metabolic acidosis; renal failure with haemoglobinuria ("blackwater fever"); hepatic failure; coagulopathy ± DIC; severe anaemia or massive intravascular haemolysis; hypoglycaemia
Pallor, petechiae, jaundice, hepatomegaly, splenomegaly (splenic rupture described)
Cerebral malaria: encephalopathy with impaired consciousness, delirium, ± seizures; focal neurological signs unusual; onset gradual or sudden following a convulsion

Inves

Suspect in any febrile illness with exposure to endemic region
Light microscopy (standard tool): Giemsa-stained blood smears
- Thin smear: erythrocyte morphology preserved; parasites visible within RBCs; for species ID + parasite density
- Thick smear: mechanical lysis of RBCs; reviews large blood quantity; for presence/absence screening + density estimation
Rapid diagnostic tests (RDTs): detect parasite antigens (HRP2, pLDH, aldolase); 15–20 min; resource-limited settings; qualitative only; can distinguish P. falciparum vs P. vivax depending on antigen
PCR (molecular): gold standard in efficacy studies; reference labs only
Uncomplicated parasitemia: <5,000 parasites/µL (<0.1% RBCs); anaemia, thrombocytopenia, elevated transaminases, mild coagulopathy, raised BUN + creatinine
Severe: parasitemia ≥4–10%; increasing parasitemia → increasing severity
Cerebral malaria: CSF normal or slightly elevated protein/cell count; retinal haemorrhages 30–40% (pupillary dilation + indirect ophthalmoscopy)
Thrombocytopenia associated with increased risk of death (falciparum or vivax), especially with severe anaemia

Mng

Inform patients of recrudescence; report to state health department
Identify chloroquine-sensitive vs resistant area
Uncomplicated, chloroquine sensitive: chloroquine monotherapy
Uncomplicated, chloroquine resistant: combination of two agents (ACTs)
Hospitalisation indications: clinical observation for tolerance; young children; immunocompromised; no acquired immunity (travellers); hyperparasitemia 4–10% without severe signs
Severe malaria — parenteral artemisinin:
- Artesunate IV/IM 2.4 mg/kg at 0, 12, 24, 48h
- OR artemether IM 3.2 mg/kg stat then 1.6 mg/kg OD
- Follow-up: ACT + primaquine (0.75 mg/kg on day 2)
- If artemisinin unavailable: quinine salt 20 mg/kg infusion then 10 mg/kg Q8H; follow-up quinine 10 mg/kg Q8H PLUS doxycycline 100 mg OD OR clindamycin 10 mg/kg BD × 7 days (clindamycin in pregnancy / child <8)

Traveller Chemoprevention

Low risk/sporadic: mosquito avoidance only
Chloroquine-resistant P. falciparum: mosquito avoidance + atovaquone-proguanil OR mefloquine OR doxycycline OR tafenoquine
Chloroquine-sensitive P. falciparum: chloroquine OR atovaquone-proguanil/tafenoquine (mefloquine, doxycycline also effective)
P. vivax dominant (Mexico / Central America): primaquine OR tafenoquine (check G6PD); chloroquine also effective
Long-term use evidence supports atovaquone-proguanil, chloroquine, doxycycline, mefloquine for up to 2 years
Timing: start before travel, continue during, and for a period after departure
If parasite-based diagnosis unavailable and suspicion high for P. falciparum: reasonable to begin empiric therapy to prevent severe disease

Special

Plasmodium parasite; female Anopheles mosquito vector (bites dusk–dawn)
P. falciparum = largest burden (sub-Saharan Africa, New Guinea, Hispaniola)
P. vivax: Americas, western Pacific
Lifecycle: bite → sporozoites travel to liver → mature → enter blood → infect RBCs (multiply 48–72h) → burst at ~2 weeks releasing merozoites (cause fever) → cyclic 2–3 days
Severe pathophysiology: cytoadherence of parasitised (+ non-parasitised) RBCs to small vessels → micro-infarcts, capillary leakage, organ dysfunction
Cerebral malaria untreated = almost universally fatal; treated mortality 15–20%
Risk factors for cerebral malaria: extremes of age, pregnancy, poor nutrition, HIV, genetics, splenectomy
Differentials:
- Dengue: myalgia more severe ("breakbone fever") — serology
- Chikungunya: dengue-like but milder/self-limiting with rash — serology
- Meningitis: no neck stiffness/photophobia in malaria; malaria has no rash
- Typhoid: bradycardia, abdominal pain, rose spots — stool/blood culture
- Leptospirosis: more severe myalgia + petechial haemorrhages (rare in malaria)
- Viral haemorrhagic fever: petechial haemorrhages common
Pneumonia: fever, cough, dyspnoea, sputum production; patients may have intercostal retractions and other signs of laboured breathing
Sepsis (bacteraemia): requires blood culture

physiology · background · low-yield

Epidemiology/Risk

WHO 2018: 219 million cases worldwide (down from 239M in 2010); most in African region (92%), then SE Asia (5%), Eastern Mediterranean (2%); ~95 countries with ongoing transmission; >85% of deaths in sub-Saharan Africa
Anaemia is common in young children in endemic areas (often multifactorial)

Microbiology

Light microscopy also diagnoses other blood parasites: filariasis, trypanosomiasis, babesiosis

Other

Clinical diagnosis: no pathognomonic clinical signs; frequently incorrect (confirmed parasitemia in febrile patients in sub-Saharan Africa often <50%)
Chemoprevention: if multiple destinations, select a single agent effective for all

Malaria - Life Cycle & Vector

Special

Life cycle: infected Anopheles bites - sporozoites into bloodstream - migrate to liver, invade hepatocytes, divide into multinucleated schizonts (pre-erythrocytic/exoerythrocytic stage) - schizonts rupture releasing merozoites into circulation - invade RBCs - within RBCs mature ring form to trophozoite to multinucleated schizont (erythrocytic stage) - some merozoites become male/female gametocytes ingested by mosquito, mature in midgut, sporozoites develop and migrate to salivary glands
Hypnozoites: quiescent liver stage existing ONLY in P. vivax and P. ovale; cause no clinical symptoms but can reactivate to cause late-onset/relapsed disease up to many months after initial infection; primaquine (and tafenoquine) is active against hypnozoites
Drug stage-activity: hepatic (pre-erythrocytic) schizonts targeted by atovaquone-proguanil and primaquine; blood-stage schizonticides = artemisinins, atovaquone-proguanil, doxycycline, mefloquine, chloroquine; primaquine acts on blood-stage schizonts of P. vivax but NOT P. falciparum
Anopheline (malaria) mosquito rests with head, thorax and abdomen in a straight line at an acute angle to the surface; Culicine mosquito rests with head and body angled and abdomen directed back toward the surface
Timeline: parasites multiply within RBCs; after ~2 weeks incubation infected cells burst and release merozoites (responsible for the fever); symptoms recur in cycles lasting 2-3 days at a time

Cerebral Malaria

C/P

Encephalopathy: impaired consciousness, delirium and/or seizures; focal neurologic signs unusual
Onset gradual or sudden following a convulsion; severity depends on parasite virulence, host immune response, and time between symptom onset and start of therapy
Risk factors: age (children and older adults), pregnancy, poor nutritional status, HIV infection, host genetic susceptibility, history of splenectomy
Can progress rapidly to coma and death; untreated almost universally fatal; with treatment mortality 15-20%

Inves

CSF examination may be normal or show slightly elevated total protein level and cell count
Retinal hemorrhages seen in 30-40% of cases (detected via pupillary dilation and indirect ophthalmoscopy)

Malaria - Traveler's Chemoprophylaxis

Mng

Selection tailored to individual itinerary; for multi-destination trips a single agent effective for the entire exposure may be simplest
Sporadic / very low-risk destinations: mosquito avoidance only, no chemoprophylaxis needed
Chloroquine-resistant P. falciparum areas: mosquito avoidance + chemoprophylaxis with atovaquone-proguanil, mefloquine, doxycycline OR tafenoquine (all four highly efficacious)
Chloroquine-sensitive P. falciparum areas: chloroquine (short-term travelers may prefer shorter course of atovaquone-proguanil or tafenoquine; mefloquine and doxycycline also effective)
P. vivax-predominant areas (e.g. malaria-endemic Mexico and Central America): primaquine or tafenoquine ONLY in absence of G6PD deficiency; chloroquine also effective
Timing: start before travel, continue regularly during exposure, and for a period after departure from the endemic area
Safe for long-term use up to 2 years: atovaquone-proguanil, chloroquine, doxycycline, mefloquine

Brucellosis

3 entries

Brucellosis (incl. Neurobrucellosis)

C/P

Disabling flu-like syndrome with non-specific signs
Undulating ("undulant") fever, sweating, chills, myalgia, arthralgia, fatigue
Also known as: remitting/relapsing fever, undulant fever, Mediterranean fever
Common symptoms: headache, cyclical fever, migratory arthralgia, myalgia, asthenia, anorexia, fatigue, malaise, weakness, sweating, vomiting, diarrhoea, abdominal pain, miscarriage
Physical: may be normal; lymphadenopathy, splenomegaly, hepatomegaly
Skin lesions: maculopapular eruptions, erythema nodosum, abscesses
Ocular: uveitis, keratoconjunctivitis, iridocyclitis, optic neuritis, cataracts
Neurological (neurobrucellosis): meningitis (nuchal rigidity, Kernig, Brudzinski), papilloedema, cranial nerve palsy, focal neurological deficits
Complications (rare if treated <1 month from symptom onset):
- Cardiovascular: endocarditis (new/changing murmurs), myocarditis, pericarditis (rub)
- Genitourinary: orchitis, epididymo-orchitis, glomerulonephritis, pyelonephritis, abortion
- CNS: meningitis, meningoencephalitis, papilledema, stroke, optic neuropathy
- Haematologic: DIC
- Musculoskeletal: sacroiliitis, arthritis, osteomyelitis, tenosynovitis
- GI/Hepatobiliary: hepatitis, hepatic abscess, acute cholecystitis, ileitis, colitis; abscess in spinal cord, spleen, thyroid

Inves

Dietary + occupational history essential
CBC: neutropenia + anaemia; thrombocytopenia (hepatosplenomegaly or immune)
Raised ESR, CRP, LDH
Elevated ALT, AST, ALK PHOS
Culture (gold standard): blood culture in tryptose medium + BACTEC system; slow-growing ≥1 week; sensitivity 10–90%
Bone marrow culture: higher yield than blood (RES concentration)
Serology (most practical): Standard Agglutination Test (SAT); indirect ELISA; repeat if initial titre low
- Titre >1:160 + compatible clinical picture → suggestive of infection
- Titre >1:320 → more specific (esp. endemic areas)
PCR / NAAT: rapid, species-specific
Radiography (spondylitis): disc space narrowing, bone destruction, sclerosis
Bone marrow aspiration/biopsy: in selected patients
Percutaneous liver biopsy: for liver granulomas — granulomatous hepatitis, hepatic microabscesses
Neurobrucellosis: CSF — lymphocytes, low glucose, elevated protein (aseptic meningitis pattern); Brucella antibodies in CSF; SAT positive
Neurobrucellosis CSF: absence of neutrophils excludes bacterial (meningococcal) meningitis

Mng

Doxycycline + (streptomycin OR rifampin OR gentamicin) OR sulfamethoxazole/trimethoprim
Several weeks needed (intracellular organism)
Avoid single-agent therapy (high relapse)
Uncomplicated: doxycycline 100 mg PO BD × 6 weeks; monotherapy relapse ≈40% so usually + rifampin 600–900 mg/day
Fluoroquinolones = secondary alternatives
Pregnancy: rifampin during pregnancy; trimethoprim–sulfamethoxazole added postpartum
Spondylitis / sacroiliitis: doxycycline + rifampin + aminoglycoside (gentamicin) × 2–3 weeks initial, then 6 weeks rifampin + doxycycline
Symptomatic: antipyretics + analgesics
Surgery: endocarditis (valve replacement); drainage of pyogenic joint effusion/paraspinal abscess; debridement + bone grafting for spondylitis
Mostly outpatient unless complicated
Avoid contact with source
Serological monitoring during treatment
Compliance essential

Prevention

Avoid infected animals; gloves + masks; avoid contaminated food
Adequate cooking of meat; pasteurisation of dairy
Lab containment
Livestock vaccination (most efficient approach)
No human vaccine available

Special

Endemic zoonotic disease (cattle, dogs, sheep, goats)
Gram-negative aerobic coccobacillus; does NOT form spores or toxins
4 human pathogenic species: B. melitensis (sheep, most virulent), B. suis (pigs, next), B. abortus (cattle), B. canis (dogs)
Bacteria in animal reproductive organs → abortions and sterility; shed in urine, milk, placental fluid
Transmission: direct animal contact; raw/unpasteurised dairy; inhalation in slaughterhouse/meat processing; butchers, lab workers high risk
Lacks classical virulence factors; pathogenesis via host cell invasion, immune evasion, chronic infection within macrophages
Incubation 3 days to several weeks
Relapse 5–15% within 6–12 months of completing therapy
Recovery 3–6 months
Overall mortality <2%
Poor prognosis with CHF due to endocarditis
Improves with physical activity rather than bed rest

physiology · background · low-yield

Microbiology

Highly infectious: as few as 10–100 organisms can cause human disease

Epidemiology/Risk

Most vulnerable occupational groups: slaughterhouse workers, veterinarians, farmers, laboratory technicians

Mechanism

Pathogenesis: ingested organisms phagocytosed → intestinal submucosa → carried to lymphoid tissue by macrophages → contained within PMNs/macrophages (avoid bactericidal responses) → spread via lymphatics; may replicate in liver, spleen, kidney, breast tissue, joints
Immune-evasion strategies: inhibiting phagocytosis, reducing bactericidal activity, diminishing endotoxic reactions, impeding antigen presentation

Other

Causes of relapse: insufficient antibiotic treatment (short duration or nonadherence); localised areas of infection

Brucellosis

C/P

Pulmonary complications: bronchitis, bronchopneumonia, hilar lymphadenopathy, lung abscess, pleural effusion
GI (additional to hepatitis/hepatic abscess/cholecystitis/ileitis/colitis): pancreatitis, primary bacterial peritonitis
CNS (additional to meningitis/meningoencephalitis/papilledema/stroke/optic neuropathy): encephalitis, psychosis, polyradiculitis, peripheral neuropathy
Cutaneous: vasculitis (alongside erythema nodosum, maculopapular eruptions, abscesses)
Genitourinary (additional): interstitial nephritis
Ocular (additional to uveitis/keratoconjunctivitis/iridocyclitis/optic neuritis/cataracts): keratitis, corneal ulcer, endophthalmitis

Inves

PCR: species-specific, detects Brucella in blood specimens
NAAT (nucleic acid amplification tests): accurate and rapid
Radiography in spondylitis: disc-space narrowing, bone destruction, sclerosis
Bone marrow aspiration/biopsy: may establish diagnosis in certain patients
Percutaneous liver biopsy (liver-granuloma patients): granulomatous hepatitis + hepatic microabscesses

Mng

Prevention: gloves + masks when handling infected animals; avoid potentially contaminated foods
Adequate cooking of meat + pasteurization of dairy products
Laboratory workers maintain appropriate containment
Animal (livestock) vaccination = most efficient approach to prevent human infection
No human vaccine currently available

Special

Genus Brucella = 12 species; 4 human-pathogenic: B. melitensis (sheep), B. suis (pigs), B. abortus (cattle), B. canis (dogs)
Infectious dose: as few as 10 to 100 organisms
More prevalent in the young; more common in males (occupational exposure); rural areas more common
Humans are incidental hosts, infected through contact with animals and animal products
Ingested organisms phagocytosed -> enter intestinal submucosa -> transported to lymphoid tissue by macrophages -> may replicate in liver, spleen, kidney, breast tissue or joints
Inhibits phagocytosis, reduces bactericidal activity, diminishes endotoxic reactions, impedes antigen presentation
Resistant to intracellular killing -> grows in phagocytes -> spreads to spleen, liver, lymph nodes, bone marrow -> host TH1 response -> granulomas form around infection foci
Insufficient antibiotic treatment (shorter duration or nonadherence to regimen) and localised areas of infection
Differential diagnosis: EBV infectious mononucleosis, infective endocarditis, influenza, malaria, meningitis, mycoplasmal pneumonia, viral hepatitis, enteric fever, acute epididymitis, urinary tract infection

Neurobrucellosis

Inves

CSF: lymphocytes (lymphocytic pleocytosis), LOW glucose, ELEVATED protein — consistent with aseptic-meningitis pattern
Brucella antibodies found in the sampled spinal fluid

Special

Absence of neutrophils in the CSF helps exclude meningococcal (pyogenic) meningitis

Helminths & Parasites

19 entries

Schistosomiasis (Bilharziasis)

C/P

Acute (Katayama fever / "swimmer itch"): sudden fever, urticaria + angioedema, chills, myalgias, arthralgias, dry cough, diarrhoea, abdominal pain, headache; 4–8 weeks post-infection
Chronic: months to years post-infection
- S. mansoni: hepatosplenomegaly + periportal fibrosis → enlarged liver/spleen → portal vein occlusion → portal hypertension with splenomegaly → portocaval shunting → GI varices
- S. haematobium: sandy patches in urinary bladder, haematuria, bladder cancer

Inves

Stool / urine microscopy for eggs (implied — deck focuses on chronic features)

Mng

Praziquantel 20 mg/kg given immediately
Repeated once 4–6 hours later
Children >4 years and adults

Special

Infection with parasitic blood flukes; bisexual flukes (only flukes with separate sexes infecting humans)
5 species: S. mansoni, S. haematobium, S. japonicum, S. intercalatum, S. mekongi
Lifecycle: eggs in faeces/urine/sputum → aquatic environment → miracidia → snail intermediate host → cercariae → penetrate definitive host (skin)
Prevention: avoid freshwater in endemic areas (Caribbean, S. America, Africa, Asia)

physiology · background · low-yield

Mechanism

Skin penetration: Schistosoma larvae are the one exception to the rule that microorganisms cannot traverse unbroken skin — they release enzymes that dissolve the adhesive proteins holding keratinocytes together

Enterobiasis (Pinworm)

C/P

Cardinal symptom: pruritus ani (perianal itch)
Most common helminthic infection in Western Europe

Inves

Clinical (implied; deck doesn't detail)

Mng

Mebendazole 100 mg immediate dose, then repeated
Treat the whole family on first occasion
Re-infection prevention: avoid scratching; scrub under fingernails; boil-wash or hot-iron bedding + clothing to kill eggs

Special

Enterobius vermicularis (pinworm / threadworm)
Gravid worms deposit eggs in perianal folds
Auto-infection by scratching → hand-to-mouth
Person-to-person via contaminated surfaces or food

Trichuriasis (Whipworm)

C/P

Most patients asymptomatic
Heavy infestation: severe GI symptoms — colitis, dysentery
Children: iron deficiency anaemia, growth retardation; rarely rectal prolapse from severe dysentery

Inves

Stool microscopy
FBC: eosinophilia likely

Mng

Albendazole 400 mg BD × 3 days (unlicensed)
Mebendazole 500 mg single dose (adults)
Mebendazole 100 mg BD × 3 days (children 1–18y)

Special

Trichuris trichiura (whipworm)
Direct nematode infection (anus → mouth, no soil)

Ascariasis

C/P

SOB, cough, abdominal pain, intestinal blockage, impaired growth

Inves

Microscopic stool exam; imaging

Mng

Self-limiting with sanitation
Albendazole / Mebendazole if needed

Special

Ascaris lumbricoides — "modified direct" nematode (faecal eggs need soil incubation)
Transmission: eggs in faecally contaminated food/water

Hookworm

C/P

Cough, itchy rash, abdominal pain, diarrhoea, anaemia, fatigue, impaired growth

Inves

Microscopic observation of eggs in stool

Mng

Albendazole, Mebendazole
Prevention: wear shoes

Special

Ancylostoma duodenale, Necator americanus
Skin-penetration nematode (larvae in soil → bare feet)

Strongyloidiasis

C/P

Often asymptomatic
Cough ± bloody, rash, abdominal pain, diarrhoea
Immunosuppressed → dissemination and fatal complications

Inves

Larvae in stool (microscopy)
Serology for antigens

Mng

Ivermectin (preferred)
Albendazole

Special

Strongyloides stercoralis
Soil-dwelling larvae penetrate skin (bare feet)

Trichinosis

C/P

Diarrhoea, abdominal cramps, fever, myalgia, headache
Severe → impaired coordination, breathing, heart function

Inves

Cysts in muscle biopsy
Immunoassays

Mng

Albendazole, Mebendazole

Special

Trichinella spiralis
From raw/undercooked pork or other meat

Taeniasis (Intestinal Tapeworms)

C/P

Asymptomatic or mild GI distress
Cysts in muscle / eye / brain (neurocysticercosis): headaches, seizures, death

Inves

Proglottids or eggs in stool
CT/MRI for cysts

Mng

Praziquantel, Niclosamide

Special

Taenia solium, T. saginata, Diphyllobothrium latum
Transmission: raw/undercooked beef or pork with larvae

Cysticercosis

C/P

Cysts in lungs, liver, brain, other tissues
Seizures, meningitis, hydrocephalus

Inves

CT or MRI to detect cysts

Mng

Surgical removal if accessible
Albendazole, Praziquantel

Special

Taenia solium larval cysts (egg exposure via faecally contaminated food/water — distinct from taeniasis which is larvae in meat)

Liver Fluke Infections

C/P

Often asymptomatic
Chronic: abdominal pain, cholangitis, gallstones

Inves

Microscopic eggs in stool

Mng

Praziquantel

Special

Clonorchis sinensis, Opisthorchis spp.
Transmission: raw/undercooked freshwater fish

Fascioliasis

C/P

Diarrhoea, abdominal pain, hepatomegaly, allergic reactions

Inves

Microscopic eggs in stool

Mng

Praziquantel

Special

Fasciola hepatica (classed as intestinal fluke in deck)
Transmission: raw/undercooked aquatic plants with cysts

Cystic Echinococcosis (Hydatid disease)

C/P

cysts in lungs, liver and other organs
nausea, GI distress, weight loss
severe anaphylaxis or death if cysts burst

Inves

imaging
serologic testing — ELISA + indirect haemagglutinin test

Mng

surgical removal or aspiration of cysts
or chemotherapy with albendazole or mebendazole

Special

exposure to eggs in feces of infected dogs or livestock
cystic cestode (tissue tapeworm), Echinococcus granulosus

Paragonimiasis (Lung fluke)

Special

Paragonimus westermani — the lung fluke on the 'Common Flukes' table
tissue trematode; named only at survey level — no clinical detail given in the lecture

Fasciolopsiasis (intestinal fluke)

C/P

diarrhoea, abdominal pain
severe cases: vomiting, nausea, intestinal obstruction, anaemia, allergic reactions

Inves

microscopic examination of eggs in stool or other samples
immunoassays

Mng

praziquantel

Special

eating raw or undercooked aquatic plants containing cysts
distinct intestinal fluke (Fasciolopsis buski) — carries the intestinal-obstruction picture; not the liver fluke Fasciola

Tissue & minor helminths (named in taxonomy only)

Special

tissue nematodes: Onchocerca, Brugia, Wuchereria, Dracunculus, Loa loa, Toxocara
intestinal flukes (trematodes): Heterophyes heterophyes, Metagonimus yokogawai
tissue cestode: Coenurosis
named in the PDF taxonomy only — no clinical detail taught

Enterobiasis (Pinworm / Oxyuris vermicularis)

C/P

pruritus ani (itching around the anus)
abdominal pain
insomnia
irritation of the female genital tract

Inves

observation of eggs or worms from the anal area
examination of samples under fingernails

Mng

mebendazole (100mg immediate dose, repeated) — treatment of choice
albendazole
pyrantel pamoate
treat the whole family on the first occasion; boil-wash / hot-iron bedding and clothing

Special

enterobiasis — Enterobius vermicularis (pinworm/threadworm)
gravid worms deposit eggs in perianal folds; scratching transfers infective eggs to the mouth (faecal-oral)

Taeniasis & cysticercosis

C/P

asymptomatic or mild GI distress
cysticercosis: cysts in muscle, eye or brain
brain cysts → headaches, seizures, or death

Inves

observation of worm segments or microscopic eggs in stool
CT or MRI to detect cysts

Mng

praziquantel or niclosamide

Special

Taenia solium, Taenia saginata, Taenia asiatica, Diphyllobothrium latum
eating raw or undercooked beef or pork from an infected animal

Liver Fluke Infections (Fasciola / Clonorchis / Opisthorchis)

C/P

chronic phase: fever, malaise, anaemia
abdominal symptoms, transaminitis
cholangitis, cirrhosis
pancreatitis, cholecystitis, gallstones

Inves

microscopic examination of eggs in stool or other samples
immunoassays

Mng

triclabendazole (PREFERRED) for Fasciola spp.
praziquantel AND albendazole for C. sinensis and Opisthorchis spp.

Special

Fasciola hepatica, F. gigantica, Clonorchis sinensis, Opisthorchis viverrini, O. felineus
eating raw/undercooked aquatic plants (Fasciola spp.) or freshwater fish (Clonorchis spp.) contaminated with eggs or cysts

Helminthic therapy (experimental immunotherapy)

Special

experimental immunotherapy — treats autoimmune diseases / immune disorders by deliberate infestation with a helminth or its eggs
induces an anti-inflammatory TH2 response, opposing the pro-inflammatory TH1 response of autoimmune disease
most autoimmune disorders involve hyperactive Th1 or Th17 responses, down-regulated by helminth-driven Th2 promotion

Surgical & Nosocomial Infection

13 entries

Blood-borne infection definitions (Toxaemia / Bacteraemia / Septicaemia / Pyaemia / Septic shock)

Use: Classic definitions distinguishing forms of blood-borne spread of infection

Toxaemia = circulation of bacterial toxins (endo- or exo-) in blood causing pathological and clinical manifestations
Bacteraemia = transient circulation of a small number of bacteria without toxic manifestations
Septicaemia = circulation and multiplication of large numbers of virulent bacteria plus their toxins in the bloodstream
Pyaemia = circulation of septic emboli arresting in different organs causing metastatic abscesses
Septic shock = clinical syndrome of acute haemodynamic disturbance causing generalized dysfunction of cardiovascular homeostasis
Bacteraemia vs septicaemia: both have viable bacteria in blood, but septicaemia has a systemic response

Broad categories of antibiotics by mechanism of action

Use: Groups surgical antibiotics by how they act; anchors endotoxin vs Gram-positive equivalent

Cell-wall active agents

Beta-lactams: penicillins, cephalosporins, monobactams, carbapenems
Several combined with beta-lactamase inhibitors to broaden spectrum

Protein synthesis inhibitors (bind ribosomes)

Aminoglycosides, tetracyclines, linezolid, clindamycin

Nucleic-acid disruptors

Fluoroquinolones; metronidazole; trimethoprim-sulfamethoxazole

Cell-wall products

Endotoxin = LPS (Gram-negative); lipoteichoic acid = Gram-positive equivalent

Antibiotics in surgery: organism-specific therapy (first choice / alternative)

Use: First-line and alternative agents per surgical pathogen

Gram-positive

MSSA: flucloxacillin / clarithromycin
MRSA: vancomycin / linezolid / daptomycin
Coagulase-negative staph: vancomycin
S. pneumoniae and S. pyogenes: benzylpenicillin (pyogenes +/- clindamycin)
Enterococci: amoxicillin / vancomycin

Gram-negative / anaerobes

Bacteroides: metronidazole / co-amoxiclav
E. coli sepsis: piperacillin-tazobactam / meropenem; UTI: trimethoprim
H. influenzae: amoxicillin
Klebsiella / Proteus: co-amoxiclav
Pseudomonas: piperacillin-tazobactam / meropenem

Clostridia

Clostridium: benzylpenicillin + metronidazole
C. difficile: stop predisposing antibiotic + metronidazole (oral vancomycin for relapse)

Classification of surgical infections: Community-acquired vs Nosocomial (HAI)

Use: Divides surgical infections by setting; drives organism spectrum and resistance expectations

Community-acquired

Active inflammatory process present before admission
e.g. peritonitis from perforated colonic diverticulum

Nosocomial (hospital-acquired)

Arises during or as a consequence of treatment
e.g. intraperitoneal abscess from a colonic anastomotic leak

Why the distinction matters

Differing spectrum of infectious disease between settings
Frequent immune deficiency in hospital patients
Higher prevalence of antibiotic-resistant organisms in hospital-acquired infection

Forms of local tissue death (LTD)

Use: Four morphological forms of local tissue death and their causes

Four forms

Sloughs
Gangrene
Sequestrum
Abscess

Causes

Bacterial exotoxin (e.g. Cl. perfringens)
Increased tissue tension (tissue oedema in a limited space or vein thrombosis)

Outcomes of host-pathogen interaction (Local vs Spread)

Use: Maps possible fates of infection into local resolution vs regional/distant spread

Local

Eradication: resolution OR organization and healing by fibrosis
Containment: suppuration leading to abscess
Chronicity

Spread - regional

Cellulitis
Lymphangitis and lymphadenitis
Thrombophlebitis

Spread - distant

Bacteraemia
Toxaemia
Septicaemia
Pyaemia with metastatic abscesses

Suppuration vs resolution vs organization

Resolution = regression, no evidence of tissue destruction
Suppuration = excessive neutrophil exudation with tissue destruction (localized = abscess; spreading = cellulitis / necrotizing soft tissue infection)
Organization and repair = damaged cells removed by phagocytosis, granulation tissue grows, tissue restored or fibrosed and scarred

Spectrum of inflammatory responses to infection

Use: Six patterns of tissue reaction to infection with representative organisms

Suppurative / purulent: staphylococcal pneumonia, abscess
Mononuclear and granulomatous: syphilis, TB
Cytopathic-cytoproliferative: HPV, herpesvirus
Tissue necrosis: Clostridium perfringens, hepatitis B
Chronic inflammation and scarring: chronic hepatitis leading to cirrhosis
No reaction (severe immune compromise): M. avium in AIDS, mucormycosis in BMT neutropenia

Streptococcus species classification with disease + antibiotic sensitivity

Use: Per-species Streptococcus disease associations and antibiotic sensitivity

S. pyogenes: upper airway and wound infections; all strains penicillin-sensitive
S. faecalis / Enterococcus: UTI, cholecystitis, wound; ampicillin-sensitive, cephalosporin-resistant
S. viridans: commensal, can cause endocarditis; penicillin-sensitive
S. pneumoniae: LRTI, conjunctivitis, sinusitis, meningitis, septicaemia (esp. splenectomised - encapsulated = virulent); penicillin and erythromycin sensitive

Routes of Microbial Infection

Use: Classifies infection by portal of entry -> major local defence -> basis for failure of that defence -> example pathogens

Skin

Example pathogens: S. aureus, Candida, Pseudomonas, Schistosoma

Gastrointestinal

Example pathogens: Vibrio, Shigella, Norovirus, C. difficile

Respiratory

Example pathogens: Influenza, H. influenzae, M. tuberculosis

Urogenital

Example pathogens: E. coli, N. gonorrhoeae, HPV

SOFA Score - Graded Per-Organ Thresholds (0-4)

Use: Graded 0-4 organ-dysfunction cut-offs summed to quantify organ failure in sepsis

Respiratory - PO2/FiO2 mmHg

0: >=400
1: <400
2: <300
3: <200 with respiratory support
4: <100 with respiratory support

Coagulation - Platelets /mm3

0: >=150,000
1: <150,000
2: <100,000
3: <50,000
4: <20,000

Liver - Bilirubin mg/dL

0: <1.2
1: 1.2-1.9
2: 2.0-5.9
3: 6.0-11.9
4: >12.0

Cardiovascular (vasopressor dose ug/kg/min)

0: MAP >=70 mmHg
1: MAP <70 mmHg
2: dopamine <5 or dobutamine (any dose)
3: dopamine 5.1-15 or norepinephrine <=0.1
4: dopamine >15 or norepinephrine >0.1

CNS - Glasgow Coma Scale

0: 15
1: 13-14
2: 10-12
3: 6-9
4: <6

Renal - Creatinine mg/dL (urine ml/d)

0: <1.2
1: 1.2-1.9
2: 2.0-3.4
3: 3.5-4.9 (urine <500)
4: >5.0 (urine <200)

Classification of health care-associated infection (HAI) - 4 main groups

Use: Organising framework for infection following surgery or hospital admission

Respiratory infections (including ventilator-associated pneumonia, VAP)
Urinary tract infections (mostly urinary catheter-related)
Bacteraemia (mostly indwelling vascular catheter-related)
Surgical site infection (SSI)

Antibiotic classification by mechanism of action

Use: Classify agents by target and spectrum to guide empirical selection

By mechanism (3 broad categories)

Cell-wall active agents - beta-lactams
Protein-synthesis inhibitors - aminoglycosides, tetracyclines, linezolid, clindamycin
Nucleic-acid disruptors - fluoroquinolones, metronidazole, TMP-SMX

Empirical spectrum - targeted-spectrum

Gram-positive: glycopeptide / lipopeptide / oxazolidinone
Gram-negative: 3rd-gen cephalosporin, monobactam, polymyxins
Anti-anaerobic: metronidazole

Empirical spectrum - broad-spectrum & special

Broad-spectrum: pip-tazo, carbapenems, fluoroquinolones, tigecycline
Plus antipseudomonal and anti-MRSA agent lists

Surgical wound contamination classes + NNIS risk index

Use: Predict SSI risk from degree of contamination plus patient/operative factors

Wound classes (infection rate; worked examples)

Clean (class I) 2.1% - hernia repair, breast biopsy
Clean-contaminated (class II) 3.3% - cholecystectomy, elective GI surgery
Contaminated (class III) 6.4% - bowel injury from trauma / inadvertent enterotomy
Dirty (class IV) 7.1% - perforated appendicitis, diverticulitis, NSTI

NNIS risk index components

ASA score higher than 2
Class III or IV wound
Operative duration greater than the 75th percentile for that procedure

Parasitology

3 entries

Helminth classification scheme (shape → residence)

Use: Classify any helminth by body shape, then by residing host organ

Nematoda (roundworms) — Nematodes

Tissue: Onchocerca, Brugia, Wuchereria, Dracunculus, Loa loa, Trichinella, Toxocara
GI: Ascaris, Strongyloides, Trichuris, Enterobius, Hookworms, Trichinella

Platyhelminthes (flatworms) — Trematodes (flukes)

Tissue: Schistosoma, Paragonimus, Fasciola
GI: Clonorchis, Opisthorchis, Fasciola, Heterophyes

Platyhelminthes (flatworms) — Cestodes (tapeworms)

Tissue: Echinococcus, Cysticercosis, Coenurosis
Intestinal: Taenia saginata, Taenia solium, Diphyllobothrium latum, Hymenolepis nana

Nematode infection-mode classification

Use: Classify roundworms (nematodes) by their route of infection

Direct (anus to mouth, no soil): Enterobius vermicularis, Trichuris trichiura
Modified direct (eggs must incubate in soil first): Ascaris lumbricoides
Skin penetration: hookworms — Ancylostoma duodenale, Necator americanus

Fluke residence-site classification ('Common Flukes')

Use: Organise trematodes (flukes) by the organ they inhabit

Lung: Paragonimus westermani
Intestine: Fasciolopsis buski, Heterophyes heterophyes, Metagonimus yokogawai
Liver: Clonorchis sinensis, Opisthorchis species, Fasciola hepatica
Blood: Schistosoma mansoni, Schistosoma haematobium, Schistosoma japonicum

Infectious Disease

2 entries

WHO Definition of Severe Falciparum Malaria

Use: Diagnostic thresholds defining severe malaria - one or more of the following occurring with P. falciparum parasitemia in the absence of an identified alternative cause

Impaired consciousness: GCS <11 in adults or Blantyre coma score <3 in children; inability to swallow
Prostration: generalized weakness - unable to sit, stand or walk without assistance
Multiple convulsions: more than 2 episodes within 24 hours
Acidosis: base deficit >8 mEq/L, plasma bicarbonate <15 mmol/L, or venous plasma lactate >=5 mmol/L (rapid, deep, labored breathing)
Hypoglycemia: glucose <40 mg/dL (<2.2 mmol/L) for children >=5y and adults; <54 mg/dL (<3 mmol/L) for children <5y
Severe anemia: Hb <=5 g/dL or Hct <=15% in children <12y (<7 g/dL and <20% in adults) with parasite count >10,000/mcL (0.2% parasitemia)
Renal impairment: creatinine >3 mg/dL (265 mcmol/L) or blood urea >20 mmol/L
Jaundice: bilirubin >50 mcmol/L (3 mg/dL) with parasite count >100,000/mcL
Pulmonary edema: radiographically confirmed, or O2 saturation <92% on room air with respiratory rate >30/min (often chest indrawing and crepitation)
Significant bleeding: recurrent/prolonged bleeding (nose, gums, venipuncture sites), hematemesis, or melena
Shock: compensated = capillary refill >=3s or temperature gradient on leg (mid-to-proximal limb) but no hypotension; decompensated = SBP <70 mmHg in children or <80 mmHg in adults with impaired perfusion (cool peripheries / prolonged capillary refill)
Hyperparasitemia: P. falciparum parasitemia >10% (>500,000/mcL)

Traveler's Malaria Chemoprophylaxis - Drug Regimens

Use: Per-drug prophylaxis regimens - target areas, timing, adult dose, pregnancy safety and contraindications

Atovaquone-proguanil (ATV/PGN)

Areas: all malarious areas
Timing: start 1 day before entering, continue up to 7 days after leaving
Adult dose: 250/100 mg daily orally
Pregnancy: not recommended
Contraindications: hypersensitivity, severe renal impairment (creatinine clearance <30 mL/min), children <11 kg

Chloroquine (CLQ)

Areas: P. vivax, P. ovale, P. malariae and chloroquine-sensitive P. falciparum areas
Timing: start 1 week before entering, continue up to 4 weeks after leaving
Adult dose: 300 mg base weekly
Pregnancy: recommended (safe)
Contraindications: hypersensitivity, epilepsy, psoriasis, retinal diseases, severe hepatic failure

Doxycycline (DOXY)

Areas: all malarious areas
Timing: start 1 day before entering, continue up to 4 weeks after leaving
Adult dose: 100 mg daily
Pregnancy: not recommended
Contraindications: cutaneous hypersensitivity, hepatic diseases, tetracycline hypersensitivity, children <8 years

Mefloquine (MFQ)

Areas: mefloquine-sensitive malaria areas
Timing: start 1 week before entering (preferably 2-3 weeks), continue up to 4 weeks after leaving
Adult dose: 250 mg base (1 tab) weekly
Pregnancy: not recommended in first trimester; not <5 kg (lack of data)
Contraindications: hypersensitivity, seizures, psychiatric disorders, cardiac conduction abnormalities