Micro: Misc Organisms

E. coli

• Lactose + on MAC with flat, dry colonies. Often beta-hemolytic on BA

• Indole (+) and oxidase (-)

• Range of endotoxins can be produced; if sorbitol neg, must r/o O157H7

Klebsiella pneumoniae

• Lac+ on MAC, mucoid

• Indole (-) and oxidase (-)

• Common cause of UTI, pneumoniae, can be MDRO

Klebsiella oxytoca

• Lac+ on MAC, mucoid

• Indole (+) and oxidase (-)

• Common cause of UTI but less common

Enterobacter cloacae

• Lac+ on MAC, mucoid, motile

• Indole (-) and oxidase (-)

• Seen in UTIs, respiratory tract, wounds, and catheter tip cultures

Klebsiella (Enterobacter) aerogenes

• Lac+ on MAC, non-motile

• Indole (-) and oxidase (-)

• Seen in UTIs, respiratory tract, wounds, and catheter tip cultures

Proteus mirabilis

• Lac - on MAC, swarming on BA, bad odor

• Indole (-) and oxidase (-)

• UTIs and wound infections

Proteus vulgaris

• Lac - on MAC, swarming on BA, bad odor

• Indole (+) and oxidase (-)

• UTIs and wound infections; not as common; often associated with immunocompromised

Morganella morganii

• Lac - on MAC, non-swarmer, smooth colonies

• Indole (+), oxidase (-), LIA = Colorless

• UTIs and wound infections

Providencia

• Lac - on MAC, non-swarmer

• Indole (+), Citrate (+), LIA = Red

• UTIs and bacteremia

Pseudomonas aeruginosa

• BA: spreading, flat, often B-hem, can be metallic or mucoid, grape-like odor. MAC: LAC - . MH: green, blue, brown pigment

• Oxidase (+) and growth at 42 C

• “Non fermenter". Associated with cystic fibrosis patients, burns, nosocomial acquisition; multidrug resistant strains an issue

Pseudomonas fluorescens/ putida group

• BA: medium-sized colonies, usually gamma hemolytic. MAC: Lac -

• Oxidase (+), no growth at 42 C

• Fluorescent pigment under Wood’s UV lamp

Stenotrophomonas maltophilia

• BA: shiny varying yellow to white colonies. MAC: Lac -

• Oxidase (-)

• Ammonia-like odor; intrinsically resistant to numerous antimicrobials (trimethoprim/ sulfa is drug of choice), nosocomial infections

Acinetobacter

• Lac +/- on MAC, white and shiny on BA, chubby/stumpy GNRs

• Oxidase (-)

• Technically a NON-fermenter; MDR strains associated with hospital outbreaks (seen in bronchial transplant patients)

Haemophilus influenzae

• BA: no growth, Gram: GNCB, non-hemolytic

• Requires X (hemin) and V (NAD) factor, ALA -

• Type b “Hib” associated with meningitis in children and is vaccine preventable; causes epiglottitis; HACEK

Haemophilus influenzae, subtype aegypticus

• BA: no growth, Gram: GNCB

• Requires X (hemin) and V (NAD) factor, ALA -

• A causative agent of bacterial conjunctivitis. “pink eye”

Haemophilus ducreyi

• Very difficult to culture, “school of fish” or “railroad tracks,” GNCB, STI haemophilus, NAT is preferred detection method

• Requires X factor only

• Causative agent of STD “soft chancroid” = painful genital ulcers

Aggregatibacter actinomycetemcomitans (FKA Actinobacillus → Haemophilus → Aggregatibacter)

• Prefers CHOC, but will grow on BA; Pinpoint at 24 hours; Sticky or adherent at 48 hours; Internal star shapes formed by older colonies on solid media, “Aggregates” into clumps in broth

• Requires increased moisture and CO2 (capnophilic)

• HACEK, Normal oral flora, associated with endocarditis and periodontal disease (sometimes severe)

Cardiobacterium hominis

• Slow growing, fastidious

• Indole (+), Oxidase (+), Catalase (-)

• HACEK, primarily associated with endocarditis

Eikenella corrodens

• Pits or “corrodes” into the agar surface, can show spreading, prefers CHOC to BA

• Oxidase (+), Nitrate (+), Indole (-), Catalase (-)

• HACEK, associated with human bite wounds, fist fights “fight bite”, periodontal disease, and endocarditis, smells like bleach

Kingella kingae

• Gram: short, plump, GNCB in pairs and chains; may resist decolorization; colony morphology varies from pinpoint to pitting to spreading to domed

• Catalase (-), Urease (-) Indole (-), Oxidase (+/-)

• HACEK, sometimes cause of infective endocarditis; significant cause of osteomyelitis/ septic arthritis in children; pathogenic in joint fluid, grows well in blood cultures

Capnocytophaga

• Fastidious (prefers CHOC but will grow on BA); high degree of polymorphism and spreading yellow colonies after 24 hours; swarming, flat; grows better in anaerobic conditions; thing, long GNRs

• Capnophilic, Catalase (-), Oxidase (-)

• GLU (+), SUC (+), LAC (V)

• Normally found in oral flora of people, cats, and dogs; associated with animal scratches or bite wounds, periodontal (gum) disease. Immunocompromised at higher risk for developing endocarditis.

Gardnerella vaginalis

• V agar: small (pinpoint - <0.5 mm at 48 hrs), convex, opaque, gray, with diffuse zone of beta hemolysis; Gram variable CB (can be beaded/ pleomorphic)

• Hemolysis (+), Oxidase (-), Catalase (-)

• Associated with bacterial vaginosis, fishy odor, clue cells may be seen (epithelial cells carpeted with bacteria

Pasteurella multocida

• BA: gray. usually non-hemolytic, GNCB, Can grow on CHOC/ BA, GNCB

• Oxidase (+)

• Transmitted most commonly through animal bites (dogs and especially cats). Cellulitis develops rapidly at site of injury

Bordetella pertussis

• Reagan Lowe: tiny colonies with a characteristic round, smooth, shiny, domed, compact appearance. They are white to gray in color. Small GNR. Sample source = nasalpharyngeal wash

• Causative agent of “whooping cough”.

Brucella sp.

• BA/CHOC: non-hemolytic grey colonies, small, slower grower; Brucella agar (CO2): small, smooth, translucent, gamma hemolytic colonies; Does not grow easy on MAC; tiny, faintly staining GNCB

• Urease (+), Oxidase (+), Non motile

• Zoonotic; species named after animal host

  • B. abortus (cattle)

  • B. melitensis (goat and sheep)

  • B. canis (dog)

  • B. suis (pigs)

• Transmission: Inhalation, consumption of unpasteurized dairy products, direct contact with broken skin

• Multiplies intracellularly in WBCs and spreads through lymphatics → bacteremia

• Can be isolated from bone marrow, liver, spleen, lymph nodes

• Occupational risk

Francisella tularensis

• Fastidious; special media to isolate: Cysteine heart (glucose) agar; faintly staining GNR

• Strict aerobe (no CO2)

• Zoonotic; multiple ways of transmission

  • vector-borne: ticks

  • gastrointestinal: eat undercooked infected animals

  • small skin abrasions: butchering rabbits → tularemia

Bartonella

• Will only grow on CHOC (not BA)

• Oxidase (-)

• B. henselae: Causes CSD (cat scratch disease)

• B. quintana: Causes “trench fever” seen in WWI and homelessness today; transmitted by human body louse

Afipia felis

• BYCE used to isolate (no CHOC/BA), GNR

• Oxidase (+), Motile

• Thought to cause CSD, but questioned

Bacillus anthracis

• BA: non-hemolytic, sticky “ground glass” colonies; colonies can be lifted off agar with loop and stand up like “beaten eggs whites”

• GPR, may have spores

• Catalase (+), non-motile

• Causative agent of anthrax (inhalation, gastrointestinal, cutaneous (most common)), Bioterrorism risk, “Woolsorter’s disease”

Bacillus cereus

• BA: beta hemolytic, large, spreading, gray-white colonies

• GPR: some with endospores

• Catalase (+), Motile

• Associated with food poisoning via toxins post cooking (fried rice)

Corynebacterium jeikium

• BA: tiny, gamma-hemolytic

• Gram: typical diptheroid palisading GPRs

• Catalase (+)

• Nosocomial acquisition; catheter-associated bloodstream infections; intrinsically resistant

Listeria monocytogenes

• BA: small, beta-hemolytic (can resemble GBS)

• Gram: GPR

• Catalase +, Tumbling motility on wet mount, “Umbrella motility" on motility agar (30C), Bile esculin (+)

• Causes listeriosis, a severe food-borne infections (associated with cheese and cold cuts), immunocompromised at higher risk, pregnant women also at elevated risk: organism can pass from mother to fetus which can lead to miscarriage, stillbirth, preterm birth, and congenital neonatal infection

Erysipelothrix

• BA: large, gamma-hemolytic colonies

• Gram: GPR, no spore

• Catalase (-), Non-motile

• Veterinary pathogen found in pigs, turkeys, horses, shellfish, fish

• Transmitted to humans through contaminated food products or close contact with farm animals

• Can cause septicemia, and an inflammatory skin infection - Erysipeloid

H. hemolyticus

• GNCB; tan, gray colonies

• Hemolysis (+), X factor (+), V factor (+)

• ALA (-)

H. parainfluenzae

• GNCB; tan, gray colonies

• Hemolysis (-), X factor (-), V, factor (+)

• ALA (+)

H. parahemolyticus

• GNCB; tan, gray colonies

• Hemolysis (+), X factor (-), V factor (+)

• ALA (+)

H. aprophilus

• GNCB; tan gray colonies

• Hemolysis (-), X factor (-), V factor (-), GLU (+), SUC (+), LAC (+), Catalase (-)

H. ducreyi

• GNCB; tan, gray colonies

• Hemolysis (-), X factor (+), V factor (-), GLU (-), SUC (-), LAC (-), Catalase (-)

Actinobacillus speciees

• GNCB; tan, smooth colonies

• GLU (+), SUC (-), LAC (-), Catalase (+), Oxidase (V)

Lactobacillus

• Catalase (-) GPR - Thin or thick GPR in chains

• Small, medium; alpha/ gamma hemolysis

• Aerobic but can grow under anaerobic conditions

• PYR (-), Vancomycin (S/R), Esculin (V), 6.5 salt (V), Growth 42C (+)

Erysipelothrix rhusiopathiae

• Catalase (-) GPR: Small rods, pleomorphic with some chains

• Small transparent or medium rough colonies

• Hemolysis: alpha, gamma

• TSI: A/A, H2S (only GPR that is H2S (+))

• Growth anaerobic (-)

Arcanobacterium hemolyticum

• Catalase (-) GPR - Diptheroid, curved, pleomorphic, slender

• Small colonies, beta-hemolysis

• TSI: A/A

• Growth Anaerobic: +/-

• No or reduced growth aneaerobically

Actinomyces pyogenes

• Catalase (-) GPR - Diptheroid, coccoid

• Pinpoint white colonies; beta-hemolysis

• TSI: NG or A/A

• Growth anaerobic: +

• Aerotolerant anaerobe; good growth anaerobically

Clostridium tertium

• Catalase (-) GPR

• Medium straight rod

• Medium gray, irregular colonies

• Alpha, gamma hemolytic

• TSI: NG

• Spore: O, T

• Growth anaerobic: +

• Aerotolerant anaerobe: Terminal spores anaerobically

Corynebacterium spp. (Diptheroids)

• Catalase (+) GPR - Diphtheroid, curved, pleo

• Pinpoint small, medium colony types, usually non-hemolytic

• No hemolysis

• Nitrate (V), KB2 (S), Urea (V+)

Corynebacterium jiekeium

• Catalase (+) GPR - Diptheroid, curved, pleo

• Pinpoint to small colonies, non-hemolytic

• Nitrate (-), KB2 (R), Urea (-), Often poor growth at 24 hours

Rhodococcus equi

• Catalase (+) GPR - Coccoid, branching filaments

• Large, moist; occasionally rough colonies

• No hemolysis

• Motility (-), Pigment: pink/ coral, Bile esculin (-), Nitrate (V)

Rothia spp. (Stomatococcus)

• Coccoid and bacilli

• Small, smooth and rough and white

• No hemolysis

• Motility (-), pigment (some black), Bile-esculin (+), Nitrate (+); sticky, probably R. mucilaginosa

Viridian Streptococci

GPC, alpha-hemolytic, Bile soluble (-), PYR (-), Bile esculin (-), 6.5% salt (-)

Non-hemolytic streptococci

Gamma hemolysis, Bile soluble (-), PYR (-), Bile esculin (-), 6.5% salt (-)

Group-D Enterococci

Gamma hemolysis, Bile soluble (-), PYR (+), Bile esculin (+), 6.5% salt (+), Vancomycin (S/R)

Group-D Non-Enterococci

Alpha/ gamma hemolysis, Bile soluble (-), PYR (-), Bile esculin (+), 6.5% salt (-)

Streptococcus pneumoniae

Alpha hemolysis, Bile soluble (+), PYR (-), Bile esculin (-), 6.5% salt (-)

Aerococcus spp

Alpha/gamma hemolysis, Bile soluble (-), PYR (v), Bile esculin (-(+)), 6.5% salt (+)

Microaerophilic Streptococci

Gamma hemolysis, Bile soluble (-), PYR (-), Bile esculin (-), 6.5% salt (-)

Nutrient deficient/ Variant Streptococci

Gamma hemolysis, Bile soluble (-), PYR (-), Bile esculin (-), 6.5% salt (-)

Rothia mucilaginosa

Gamma hemolysis, Bile soluble (-), PYR (+), Bile esculin (-), 6.5% salt (-)

Leuconostoc

• Cocco-bacillary, PYR (-), Vancomycin(R), Esculin (V), 6.5 salt (V), Growth 42C (-), LAP (-)

Pediococcus

• Large cocci in tetrads, PYR (-), Vancomycin (R), Esculin (V), 6.5 salt (V), Growth 42C (+), LAP (+)