Bacteriology Flashcards
Blood culture collection
High-volume (~20mL), multiple over 24hrs (ideally 3+)
Gram stain (including quality checks)
Crystal violet, gram iodine, decolorizer, safranin
PMNs should be PINK. Also count squames on directly sampling (<10 to culture)
Specialized bacterial stains
Methylene blue: Stool polys, diphtheria
Wayson: Yersinia pestis
Acridine orange: For morphology in poorly-staining organisms
For what organisms are fluorescent antibodies available?
Legionella
Bordetella
Chlamydia
For what organisms are rapid EIAs available?
Pneumococcus (urine)
H. Pylori
Campylobacter
Legionella
Staph Aureus
Gram-positive cocci in clusters
Beta-hemolytic.
Catalase +. Slide coag +, Tube coag +
Virulence factors: PROTEIN A, exfoliatin, TSST, PVL, enterococci
Staph Epidermidis
Gram-positive cocci
Catalase +. Coagulase -. NOVOBIOCIN SENSITIVE
Staph Saprophyticus
Gram-positive cocci
Catalase -? Coagulase -. NOVOBIOCIN RESISTANT
Staph Haemolyticus
Gram-positive cocci.
Intrinsically vancomycin resistant.
Grows poorly on routine agar; grows well on Chocolate.
Staph Lugdunensis
Gram-positive cocci
Catalase +. Slide coagulase +, tube -.
Micrococci
Gram-positive cocci in TETRADS.
Catalase +
Microdase (modified oxidase) positive.
Non-glucose fermenter (unlike staph).
Yellow cultures (M. Luteus)
Rothia mucilaginosa
Gram-positive cocci.
Mucoid, sticky colonies.
Strep Pyogenes
Gram-positive cocci in chains.
Beta-hemolytic.
PYR+
Bacitracin-susceptible.
Intrinsically bactrim-resistant.
Virulence factors: M protein, capsule, streptolysin O (labile), S (stable).
Strep Agalactiae
Gram-positive cocci.
Beta-hemolytic.
CAMP test +.
Hippurate +.
Screen pregnant mothers with PCR or LIM/Carrot broth agar
Strep Pneumoniae
Group positive cocci in pairs.
Alpha-hemolytic.
Optochin sensitive. Bile sensitive/soluble.
Rapid urine antigen test available
Strep Viridans (and subgroups)
Gram-positive cocci.
Alpha-hemolytic.
Optochin-resistant.
Examples: Anginosus, constellatus, intermedius, and ABIOTRPHIA/GRANULICATELLA (nutritionally deficient)
Strep Bovis
Gram-positive cocci.
Gamma-hemolytic.
Colorectal carcinoma.
Bile resistant. Salt sensitive.
Aerococcus
Gram-positive cocci in TETRADS.
Coagulase -.
Alpha-hemolytic.
Urinae: PYR negative, LAP positive
Viridans: PYR positive, LAP negative
Leconostoc, pediococcus
Gram-positive cocci.
Rare pathogens, but intrinsically vancomycin resistant.
Neisseria Gonorrhoeae
Gram-negative cocci.
Oxidase +
Ferments glucose only.
Hard to isolate»_space; chocolate agar, direct gram stain, NAAT.
Neisseria Meningitidis
Gram-negative cocci in pairs.
Oxidase +.
Ferments maltose and glucose.
13 serovars. Vaccine covers A/C/Y/W135. B is poorly immunogenic.
Hard to grow»_space; Chocolate agar.
Chemoprophlax close contacts (rifampin)
Moraxella catarrhalis
Gram-negative cocci. Oxidase +. Indoxyl butyrate +. Does not ferment (asaccharolytic). Hockey-puck motility. Intrinsically ampicillin resistant.
Corynebacterium Diphtheria
Gram-positive pleomorphic bacilli.
Catalase+
UIncommon. Toxin producing»_space; ELEK TEST
Grows on tellurite/tinsdale agar.
Corynebacterium, other than diphtheria
Jeikeium: Broad intrinsic resistances. Associated with indwelling devices
Urealyticum: Broad intrinsic resistances. Urease+»_space; Struvite stones in UTI.
Arcanobacterium haemolyticum
Gram-positive coccobacillus
Beta-hemolytic
Resembles TAS, but REVERSE CAMP TEST positive
Listeria monocytogenes
Gram-positive bacillus. Beta-hemolytic. Catalase + Cold, aerophilic. Bile esculin sensitive Intrinsically resistant to cephalosporin.
Erysipelothrix
Pigs, erysipeloid skin infections.
Esculin negative?
Hydrogen sulfide-producing.
Intrinsically vancomycin resistant.
Bacillus anthracis
Gram-positive bacillus. Sporulating. Aerobic.
Nonhemolytic. NONMOTILE.
Tenacious colonies with border projections
Bacillus cereus
Gram-positive bacillus. Sporulating. Aerobic.
Beta-hemolytic and motile.
Produces heat-labile and heat-stable toxins.
Enterobacteraceae
Gram-negative rods, facultative anaerobes, glucose-fermenting.
Lactose fermenters: Escherichia, Klebsiella, Proteus, Entero/Citrobacter
Non-lactose fermenters: Salmonella, Shigella, Serratia, Yersinia
Escherichia Coli
Indole +, Citrate -. Oxidase-.
Lactose fermenter (PINK)
Slant: A/A with gas
O157:H7 - Sorbitol MacConkey agar, produces verotoxin
Klebsiella
Enterobacteriaceae.
Lactose fermenter (PINK)
Variable biochemical features depending on species.
Mucoid colonies, thick mucopolysaccharide capsule.