STEPTRACKERMICROBIOLOGY | CLINICAL CLUES | RAPID-FIRE REVIEW

Buzzword → Organism

The exposure or clinical clue that should make one organism jump to mind — each row links back to the page that explains it.

FOCUS ON
Clues come in four kinds: exposure (animal, food, water, travel, job), host (asplenia, CD4, neutropenia, CF, sickle cell, diabetes), time course (hours after a meal, days after a tick bite, years after measles) and signature lesion (rash pattern, eschar, ulcer, inclusion). When two organisms share a clue, the host or exposure usually breaks the tie. Full lab-based clues are on 12.02.
CLUE
ORGANISM
WHY
PAGE
Cat scratch → tender regional node
Bartonella henselae
Kitten fleas carry it
4.07
Cellulitis within 24 h of a cat/dog bite
Pasteurella multocida
Animal mouth flora
4.07
Hunter skinning rabbits, ulcer + nodes
Francisella tularensis
Ulceroglandular tularemia
4.07
Unpasteurized goat cheese, relapsing fever
Brucella
Undulant fever
4.07
Farmer, livestock births, pneumonia, no rash
Coxiella burnetii
Inhaled spores
3.03
Spelunker, bat guano, hilar nodes
Histoplasma
Ohio/Mississippi valleys
8.01
Desert dust, erythema nodosum
Coccidioides
Southwest US
8.01
Rose thorn → ascending nodules
Sporothrix schenckii
Lymphocutaneous spread
8.01
Air conditioning, hyponatremia, diarrhea
Legionella
Water aerosols
4.03
Hot tub folliculitis · nail through sneaker
Pseudomonas
Water-loving, rubber-loving
4.03
Raw oysters + cirrhosis → bullae, sepsis
Vibrio vulnificus
Iron-rich host
4.05
Reheated rice → vomiting in 2 h
Bacillus cereus
Preformed emetic toxin
10.03
Deli meat, soft cheese, pregnancy
Listeria
Grows in the cold
2.05
Honey in an infant → floppy baby
C botulinum spores
Toxin made in infant gut
2.04
Rash starting at wrists/ankles after a tick bite
Rickettsia rickettsii
Vasculitis, spreads to trunk
3.03
Bull's-eye rash after hiking in the Northeast
Borrelia burgdorferi
Ixodes tick
4.08
Flood water, conjunctival suffusion, jaundice
Leptospira
Rat urine
4.08
Warm lake swim → fatal meningitis in days
Naegleria fowleri
Through cribriform plate
9.02
Asplenic patient + dog bite → sepsis
Capnocytophaga
Dog mouth flora
10.07
Sickle cell + osteomyelitis
Salmonella
Functional asplenia, bone infarcts
10.06
DKA + black nasal eschar
Mucor / Rhizopus
Acid, glucose, iron
8.02
Fish tank → hand granulomas
M marinum
Grows at skin temperature
3.02

Mechanism — why exposure clues work

ReservoirAnimal, soil, water, human
→
RouteBite, inhalation, ingestion, vector
→
Portal of entrySkin, lung, gut
→
Organ syndrome

Ask the reservoir and route first; the organ syndrome then narrows to one or two organisms.

Rash-location clues

PATTERN
ORGANISM
PAGE
Palms and soles
RMSF, secondary syphilis, coxsackie A
Trunk first, spares face
Epidemic typhus
Head down, Koplik first
Measles
Slapped cheek → lacy
Parvovirus B19
Sandpaper, flexural lines
Scarlet fever (GAS)
Dermatome
VZV

How it's tested

COMMON CONFUSIONCat bite (Pasteurella, hours) vs cat scratch (Bartonella, days–weeks, node) vs cat feces (Toxoplasma) — same animal, three organisms.
THE TRAPA buzzword can be planted as a distractor — confirm it fits the host and time course before committing.
YOUR APPROACHPick out the exposure, host and timing words in the stem → match to the organism → confirm with the syndrome.

If you see… think…

Parrot owner → C psittaci
Prairie dogs, New Mexico, buboes → Y pestis
Deer mouse droppings, pulmonary edema → hantavirus
Pigeon droppings, AIDS meningitis → Cryptococcus
Bird roosts and caves → Histoplasma
Reptile pet → Salmonella
Puppy and bloody diarrhea → Campylobacter
Cat litter in pregnancy → Toxoplasma
Undercooked pork → Taenia solium, Trichinella, Yersinia
Raw freshwater fish → Diphyllobothrium, Clonorchis