Bacteriology Flashcards

1
Q

Blood culture collection

A

High-volume (~20mL), multiple over 24hrs (ideally 3+)

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2
Q

Gram stain (including quality checks)

A

Crystal violet, gram iodine, decolorizer, safranin

PMNs should be PINK. Also count squames on directly sampling (<10 to culture)

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3
Q

Specialized bacterial stains

A

Methylene blue: Stool polys, diphtheria
Wayson: Yersinia pestis
Acridine orange: For morphology in poorly-staining organisms

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4
Q

For what organisms are fluorescent antibodies available?

A

Legionella
Bordetella
Chlamydia

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5
Q

For what organisms are rapid EIAs available?

A

Pneumococcus (urine)
H. Pylori
Campylobacter
Legionella

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6
Q

Staph Aureus

A

Gram-positive cocci in clusters
Beta-hemolytic.
Catalase +. Slide coag +, Tube coag +

Virulence factors: PROTEIN A, exfoliatin, TSST, PVL, enterococci

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7
Q

Staph Epidermidis

A

Gram-positive cocci

Catalase +. Coagulase -. NOVOBIOCIN SENSITIVE

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8
Q

Staph Saprophyticus

A

Gram-positive cocci

Catalase -? Coagulase -. NOVOBIOCIN RESISTANT

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9
Q

Staph Haemolyticus

A

Gram-positive cocci.
Intrinsically vancomycin resistant.
Grows poorly on routine agar; grows well on Chocolate.

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10
Q

Staph Lugdunensis

A

Gram-positive cocci

Catalase +. Slide coagulase +, tube -.

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11
Q

Micrococci

A

Gram-positive cocci in TETRADS.
Catalase +
Microdase (modified oxidase) positive.
Non-glucose fermenter (unlike staph).

Yellow cultures (M. Luteus)

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12
Q

Rothia mucilaginosa

A

Gram-positive cocci.

Mucoid, sticky colonies.

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13
Q

Strep Pyogenes

A

Gram-positive cocci in chains.
Beta-hemolytic.
PYR+
Bacitracin-susceptible.

Intrinsically bactrim-resistant.

Virulence factors: M protein, capsule, streptolysin O (labile), S (stable).

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14
Q

Strep Agalactiae

A

Gram-positive cocci.
Beta-hemolytic.
CAMP test +.
Hippurate +.

Screen pregnant mothers with PCR or LIM/Carrot broth agar

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15
Q

Strep Pneumoniae

A

Group positive cocci in pairs.
Alpha-hemolytic.

Optochin sensitive. Bile sensitive/soluble.

Rapid urine antigen test available

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16
Q

Strep Viridans (and subgroups)

A

Gram-positive cocci.
Alpha-hemolytic.
Optochin-resistant.

Examples: Anginosus, constellatus, intermedius, and ABIOTRPHIA/GRANULICATELLA (nutritionally deficient)

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17
Q

Strep Bovis

A

Gram-positive cocci.
Gamma-hemolytic.

Colorectal carcinoma.

Bile resistant. Salt sensitive.

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18
Q

Aerococcus

A

Gram-positive cocci in TETRADS.
Coagulase -.
Alpha-hemolytic.

Urinae: PYR negative, LAP positive
Viridans: PYR positive, LAP negative

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19
Q

Leconostoc, pediococcus

A

Gram-positive cocci.

Rare pathogens, but intrinsically vancomycin resistant.

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20
Q

Neisseria Gonorrhoeae

A

Gram-negative cocci.
Oxidase +
Ferments glucose only.

Hard to isolate&raquo_space; chocolate agar, direct gram stain, NAAT.

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21
Q

Neisseria Meningitidis

A

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&raquo_space; Chocolate agar.

Chemoprophlax close contacts (rifampin)

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22
Q

Moraxella catarrhalis

A
Gram-negative cocci.
Oxidase +. Indoxyl butyrate +. 
Does not ferment (asaccharolytic).
Hockey-puck motility.
Intrinsically ampicillin resistant.
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23
Q

Corynebacterium Diphtheria

A

Gram-positive pleomorphic bacilli.
Catalase+
UIncommon. Toxin producing&raquo_space; ELEK TEST
Grows on tellurite/tinsdale agar.

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24
Q

Corynebacterium, other than diphtheria

A

Jeikeium: Broad intrinsic resistances. Associated with indwelling devices
Urealyticum: Broad intrinsic resistances. Urease+&raquo_space; Struvite stones in UTI.

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25
Q

Arcanobacterium haemolyticum

A

Gram-positive coccobacillus
Beta-hemolytic

Resembles TAS, but REVERSE CAMP TEST positive

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26
Q

Listeria monocytogenes

A
Gram-positive bacillus.
Beta-hemolytic. Catalase +
Cold, aerophilic.
Bile esculin sensitive
Intrinsically resistant to cephalosporin.
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27
Q

Erysipelothrix

A

Pigs, erysipeloid skin infections.
Esculin negative?
Hydrogen sulfide-producing.
Intrinsically vancomycin resistant.

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28
Q

Bacillus anthracis

A

Gram-positive bacillus. Sporulating. Aerobic.
Nonhemolytic. NONMOTILE.

Tenacious colonies with border projections

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29
Q

Bacillus cereus

A

Gram-positive bacillus. Sporulating. Aerobic.
Beta-hemolytic and motile.

Produces heat-labile and heat-stable toxins.

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30
Q

Enterobacteraceae

A

Gram-negative rods, facultative anaerobes, glucose-fermenting.

Lactose fermenters: Escherichia, Klebsiella, Proteus, Entero/Citrobacter
Non-lactose fermenters: Salmonella, Shigella, Serratia, Yersinia

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31
Q

Escherichia Coli

A

Indole +, Citrate -. Oxidase-.
Lactose fermenter (PINK)
Slant: A/A with gas
O157:H7 - Sorbitol MacConkey agar, produces verotoxin

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32
Q

Klebsiella

A

Enterobacteriaceae.
Lactose fermenter (PINK)
Variable biochemical features depending on species.

Mucoid colonies, thick mucopolysaccharide capsule.

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33
Q

Enterobacter, Citrobacter

A

Enterobacter: Lactose-fermenter (PINK). Indole -.
Citrobacter: Non-lactose-fermenter (CLEAR). Citrate +.

34
Q

Proteus

A
Enterobacteriaceae
Non-lactose fermenter (CLEAR). Urease+, H2S-producer.
Swarming motility
Vulgaris: Indole+
Milabilis: Indole-. ODC+
35
Q

Serratia

A

Enterobacteriaceae
Brick-red colonies due to prodigiosin production
Marsescens: DNAse+. Others not.

36
Q

Salmonella

A

Enterobacteriaceae. Motile
Non-lactose fermenters (clear)
H2S producers (black on Hektoen) except Typhi

O (wall), H (flagellum), Vi (capsule) antigens

37
Q

Shigella

A

Enterobacteriaceae. Nonmotile
Non-lactose fermenter (CLEAR).
Non-H2S producer (Green on Hektoen)
Slant: K/A.

Species: A (dysenteriae), B (Flexneri), C (Boydii), D (Sonnei - common)

38
Q

Yersinia

A
Enterobacteriaceae
Non-lactose fermenter (CLEAR)
Enterocolitica is cold-lover, TTI
Safety-pin morphology with methylene blue
CIN agar for Y. Enterocolitica
Salmon on Hektoen
39
Q

Plesiomonas Shigelloides

A

Gram-negative bacillus, weak pathogen. Associated with cold-blooded animals.

40
Q

Vibrio

A

Gram-negative bacillus. Comma shaped, motile.
Oxidase+, glucose-fermenter. Lactose-fermenter?
Halophilic; grows on TCBS agar (yellow)

Species: Cholera, Vulnificus (BAD), parahaemolyticus

41
Q

Aeromonas

A

Gram-negative bacillus. Water-associated.
Beta-hemolytic.
Oxidase, indole+.

Leeches

42
Q

Chromobacterium

A

Gram-negative bacillus. Water associated.

Produces hydrogen cyanide.

43
Q

Glucose non-fermenters

A

Pseudomonas
Stenotrophomonas
Acinetobacter
Burkholderia

44
Q

Pseudomonas

A

Gram-negative bacillus.
Oxidase+, catalase+
Green diffusible pigment. Grape odor.
Can grow at 42 C.

45
Q

Stenotrophomonas

A

Gram-negative bacillus.
Oxidase-negative. Motile.

Expresses extracellular DNase

Sensitive to bactrim

46
Q

Acinetobacter

A

Gram-negative coccobacillus
Oxidase-negative. Catalase+??? Nonmotile

Extensively antibiotic resistant.

47
Q

Burkholderia

A

Gram-negative bacilli.
Oxidase weakly +.

Cepacia: Lysine decarboxylase. CF.
Pseudomallei: Melioidosis
Mallei: Glanders, rare skin infxn

48
Q

Haemophilus

A

Gram-negative coccobacillus. Fastidious.

Influenzae: Many serovars. Needs X+V.
Aprophilus: Needs nothing.
Parainfluenzae: Needs V.
Ducreyi: Needs X.

49
Q

Capnocytophaga

A

Gram-negative, long fusiform filamentous bacteria

Gliding motility. Oxidase+

Dog bites

50
Q

Pasteurella

A

Gram-negative bacilli. Oxidase+

Animal bites (especially cat)

Won’t grow on MacConkey.

Universally sensitive to penicillin.

51
Q

Bordetella

A

Gram-negative bacillus
Difficult to culture, best identified with PCR, DFA. Collect sample early.
Grows on Regan-Lowe / Bordet-Gengou agar

52
Q

Brucella

A

Gram-negative bacillus.
Zoonotic infections. Melitensis (sheep), abortus (cattle), suis (sheep), canis (dogs). Undulant fever.
Usually diagnosed with serology.
Characeristically strong urease, oxidase, and catalase reactivity.

53
Q

Francisella

A

Gram-negative bacillus

Deerfly vector, rodent reservoir. Causes ulceroglandular disease.

Requires cysteine to culture. Oxidase and urease negative.

54
Q

Legionella

A

Gram-negative bacillus
Diagnosed with DFA or urine antigen testing. Or serology.
Cultured on BCYE agar (needs cysteine)

55
Q

Bartonella

A

Gram-negative bacillus
Quintana - Trench fever
Henselae - Cat-scratch disease

Fastidious, needs chocolate agar. Diagnose with serology or NAT.

56
Q

Campylobacter

A
Gram-negative gullwings. 
Need selective media (Campy CVA).
Rapid EIA available
Jejuni - Hippurate positive
Fetus - Hippurate negative.
57
Q

H. Pylori

A

Gram-negative curved organism
Urease+.
Diagnose with stool PCR (better than antigen test or culture). Urease breath test. Don’t bother with serology.

58
Q

Mycoplasma, ureaplasma

A

No cell wall.

Mycoplasma: Causes atypical pneumonia. Microscopic fried-egg colonies.
Ureaplasma: Causes genital tract infections. Raspberry colonies.

59
Q

Chlamydia trachomatis

A

Intracellular bacterium. Causes Trachoma, genital infection, LGV.

Culture requires a cell line. Use NAT/IF instead.

Elementary body is infectious, reticulate body is replicative.

60
Q

Rickettsia

A

Transmitted by Dermacentor tick, causes RMSF

Diagnose by DFA, PCR, or serology. Historical: Weil-Felix reaction

61
Q

Coxiella

A

Zoonotic infection with no vector.

Causes Q fever (Acute: Phase II IgM/IgG. Chronic: Phase I and II IgM/IgG)

Fibrin ring granulomas, endocarditis

62
Q

Ehrlichia / Anaplasma

A

Intracellular gram-negative (monocytes)

Elementary body (infectious), reticulate body (replicative)

Transmitted by Amblyomma / Ixodes ticks, respectively

63
Q

Borrelia

A
Lyme (burgdorferi)
Relapsing fever (recurrentis)

Loose coils in peripheral blood smear.

Ixodes (deer) tick

Serology or direct visualization dx. PCR not often used.

64
Q

Leptospira

A

Spirochetal organism contracted through water exposure.

Rodents normal host.

Presents with systemic features.

Diagnose with serology, darkfield microscopy

65
Q

Treponema

A

Diagnose with darkfield microscopy, treponemal&raquo_space; nontreponemal tests.

Increasing in MSM population

VDRL test of choice for CSF

66
Q

Bacteroides

A

Anerobic, gram-negative pleomorphic

Fragilis: #1 anaerobe of abdominal infections
Ureolyticus: Pits agar. H&N infections.

67
Q

Prevotella

A

Anaerobic gram-negative bacillus

Oral cavity mucosae, GI tract.

Black pigment on kanamycin-vancomycin agar. Red fluorescence?

68
Q

Fusobacterium

A

Anaerobic, filamentous bacterium. Causes H&N infections.

Nucleatum: Pointed end

Necrophorum: Pleomorphic, aggressive. Lipase+

69
Q

Anaerobic cocci

A

Peptostreptococcus: Gram-positive
Veillonella: Gram-negative

70
Q

Cuti/propionibacterium acnes

A

Skin commensal. Causes joint infections.

71
Q

Clostridium species

A

Botulinum: Wound infection > infant botulism
Tetani: Spores&raquo_space; tetanospasmin
Septicum: Colorectal carcinomas
Difficile: A and B cytotoxins&raquo_space; PCR gene better than EIA.
Perfringens: Double-layer hemolysis. Many toxins.

72
Q

Enterococcus

A

Gram-positive cocci.
Variable hemolysis, usually gamma.

Faecalis (arabinose negative) more common than faecium (arabinose positive)

73
Q

Slant agar

A

Butt - Glucose
Slant - Lactose or sucrose

Starts as red; indicator turns yellow with acidity.

74
Q

Molecular strain typing

A

Pulsed-field gel electrophoresis (RFLP method?)

75
Q

Gardnerella

A

Small, gram-negative (or variable)_

76
Q

Catalase

A

Positive: Staph, Micrococcus, Listeria

77
Q

Novobiocin

A

Staph epidermidis - Sensitive

Staph saprophyticus - Resistant

78
Q

Optochin

A

Pneumococcus - Sensitive

Strep viridans - Resistant

79
Q

CAMP test

A

Positive: GBS, Listeria

80
Q

Reverse CAMP test

A

Positive: Arcanobacterium, C. Perfringens

81
Q

Bacitracin

A

Group A strep - Sensitive

Group B strep - Resistant

82
Q

Hippurate

A

Positive: GBS, Campylobacter jejuni (not fetus)