Gram-positive, non-spore-forming bacilli

Question 1

General characteristics of Corynebacterium spp., Listeria spp., Erysipelothrix spp., and others

Answer 1

Gram-positive, non-spore-forming bacilli

Question 2

Arrangement under the microscope short, slightly curved rods with rounded ends arranged in palisades (Chinese V, L characters, Babes-Ernst granules, Lamb strain)

Answer 2

Corynebacterium

Question 3

Corynebacterium diphtheriae habitat

Answer 3

Not part of normal flora; found in the nasopharynx of carriers

Question 4

Virulence factor of C. diphtheriae

Answer 4

Tox gene via transduction; diphtheria toxin inhibits protein synthesis, leading to cell destruction

Question 5

Biotypes of C. diphtheriae: Intermedius

Answer 5

Small, gray, translucent, β-hemolytic colony

Question 6

Biotypes of C. diphtheriae: Mitis

Answer 6

Medium-sized, convex, smooth, black pigment, fried-egg appearance, β-hemolytic colony

Question 7

Biotypes of C. diphtheriae: Belfanti

Answer 7

Medium-sized, grayish-black, opaque, β-hemolytic colony

Question 8

Biotypes of C. diphtheriae: Gravis

Answer 8

Large, flat, glossy, grayish-black, daisy-head appearance, non-hemolytic colony

Question 9

Toxigenic strains causes respiratory disease with gray-white pseudomembrane in the throat

Answer 9

Corynebacterium diphtheriae

Question 10

Non-toxigenic strains of Corynebacterium diphtheriae causes

Answer 10

cutaneous diphtheria (Velat sore/Barcoo rot) with nonhealing ulcers and infections in immunocompromised individuals

Question 11

Presumptive test for Corynebacterium diphtheriae seen in agar

Answer 11

Brown-black colonies with gray-brown halo on Tinsdale agar

Question 12

Media and nutrients for Corynebacterium diphtheriae

Answer 12

Tinsdale and Loeffler medium; requires cystine; no increased CO2 required

Question 13

Tests for toxigenic strain identification in C. diphtheriae

Answer 13

ELEK immunodiffusion test, tissue culture, EIA, PCR, Schick skin test, Roemer test (Guinea pig virulence test)

Question 14

Zoonosis and infections associated with cattle; causes diphtheria-like sore throat and pneumonia; linked to summer outbreaks and bovine mastitis

Answer 14

Corynebacterium ulcerans

Question 15

Zoonosis and infections associated with sheep, goats, and horses; causes suppurative granulomatous lymphadenitis

Answer 15

Corynebacterium pseudotuberculosis

Question 16

Bacteria that resemble colonies of C. diphtheriae; positive for urease and reverse CAMP test

Answer 16

C. ulcerans and C. pseudotuberculosis

Question 17

Corynebacterium infections that is the colonizer of male genitourinary tract; causes prostatitis and non-gonococcal urethritis (NGU); positive CAMP, glucose, and sucrose fermentation

Answer 17

Corynebacterium glucuronolyticum

Question 18

Part of the normal flora and is also seen in skin of hospitalized patients in inguinal, axillary, or rectal sites; also intravenous catheters

Answer 18

Corynebacterium jeikeium

Question 19

Causative agent of septicemia, skin infections, malignancies, neutropenia, and infections in AIDS patients, catheters, prosthetic valves, CSF shunts

Answer 19

Corynebacterium jeikeium

Question 20

Growth characteristics of Corynebacterium jeikeium

Answer 20

Enhanced growth with lipids (add Tween 80 or serum); negative nitrate and urease tests

Question 21

Causative agent for septicemia, endocarditis, pneumonia, and lung abscesses in immunocompromised patients; positive for nitrate and urease tests

Answer 21

Corynebacterium pseudodiphtheriticum

Question 22

Causative agent of UTI and wound infections in elderly and immunocompromised patients; growth characteristics of ehanced growth with lipids (add Tween 80 or serum); rapid urease positive

Answer 22

Corynebacterium urealyticum

Question 23

Characteristic finding in Corynebacterium urealyticum urine samples that is also seen in Proteus spp.

Answer 23

Struvite crystals

Question 24

Causative agent of erythrasma (superficial, chronic pruritic reddish-brown macules on skin); diagnostic feature of coral red fluorescence under Wood lamp

Answer 24

Corynebacterium minutissimum

Question 25

Sources of includes meat, processed foods (ham, hotdogs, cold cuts, deli meats), soft cheese (Mexican-style, feta, brie, Camembert, blue-veined), vegetables, dairy products (milk), or colonized mother to fetus

Answer 25

Listeria monocytogenes

Question 26

Virulence factors of Listeria monocytogenes

Answer 26

Listeriolysin O (pore-forming toxin), Siderophores (iron acquisition), Phospholipase (WBC escape), E-cadherin (placental invasion), Internalin (induces phagocytosis), Act A (actin polymerization)

Question 27

Diseases caused by Listeria monocytogenes

Answer 27

Systemic: Bacteremia; CNS: meningitis, encephalitis, brain abscess, spinal cord infections; Neonatal Listeriosis (Granulomatosis infantisepticum); Immunocompromised infections

Question 28

Microscopic morphology short gram-positive bacilli occurring singly or in short chains

Answer 28

Listeria monocytogenes

Question 29

Motility characteristics of Listeria monocytogenes

Answer 29

Tumbling motility in nutrient broth at RT (1-2 hours); Umbrella-like or inverted Christmas tree growth in SIM at 22-25°C

Question 30

Cold enrichment for Listeria monocytogenes

Answer 30

Specimen stored at 4°C for weeks to months

Question 31

Selective media for Listeria monocytogenes

Answer 31

PAL-CAM and McBride medium

Question 32

Diagnostic test for Listeria monocytogenes causing conjunctivitis in rabbits

Answer 32

Anton test (positive for purulent conjunctivitis)

Question 33

Positive tests for Listeria monocytogenes

Answer 33

Catalase, CAMP (block-type hemolysis), Voges-Proskauer, Esculin

Question 34

Negative tests for Listeria monocytogenes

Answer 34

H2S and Urease

Question 35

Causative agent of zoonosis in veterinarians, meat butchers, and fish handlers; causes erysipeloid or butcher's cut

Answer 35

Erysipelothrix rhusiopathiae

Question 36

Virulence factors of Erysipelothrix rhusiopathiae

Answer 36

Capsule, Neuraminidase, Hyaluronidase, Surface proteins

Question 37

Microscopic and culture characteristics of Erysipelothrix rhusiopathiae

Answer 37

Gram-positive short bacilli forming long filaments; Alpha-hemolytic on BAP

Question 38

Diagnostic features H2S positive in TSI; Test-tube brush or pipe-cleaner appearance in gelatin stab culture at 22°C; Negative catalase, oxidase, esculin, nitrate, urease

Answer 38

Erysipelothrix rhusiopathiae

Question 39

Zoonosis associated with cattle, sheep, dogs, cats, and pigs; Reverse CAMP positive

Answer 39

Arcanobacterium haemolyticum

Question 40

Microscopic features curved Gram-positive rods with pointed ends and rudimentary branching

Answer 40

Arcanobacterium haemolyticum

Question 41

Normal flora of vagina, GI tract, and mouth; pleomorphic and alpha-hemolytic on BAP

Answer 41

Lactobacillus acidophilus

Question 42

Microscopic forms of Lactobacillus acidophilus

Answer 42

Pleomorphic: long chaining bacilli, coccobacilli, spiral forms

Question 43

Positive CAMP test and its result

Answer 43

Streptococcus agalactiae; Arrowhead hemolysis with S. aureus