Gram-positive, non-spore-forming bacilli Flashcards
General characteristics of Corynebacterium spp., Listeria spp., Erysipelothrix spp., and others
Gram-positive, non-spore-forming bacilli
Arrangement under the microscope short, slightly curved rods with rounded ends arranged in palisades (Chinese V, L characters, Babes-Ernst granules, Lamb strain)
Corynebacterium
Corynebacterium diphtheriae habitat
Not part of normal flora; found in the nasopharynx of carriers
Virulence factor of C. diphtheriae
Tox gene via transduction; diphtheria toxin inhibits protein synthesis, leading to cell destruction
Biotypes of C. diphtheriae: Intermedius
Small, gray, translucent, β-hemolytic colony
Biotypes of C. diphtheriae: Mitis
Medium-sized, convex, smooth, black pigment, fried-egg appearance, β-hemolytic colony
Biotypes of C. diphtheriae: Belfanti
Medium-sized, grayish-black, opaque, β-hemolytic colony
Biotypes of C. diphtheriae: Gravis
Large, flat, glossy, grayish-black, daisy-head appearance, non-hemolytic colony
Toxigenic strains causes respiratory disease with gray-white pseudomembrane in the throat
Corynebacterium diphtheriae
Non-toxigenic strains of Corynebacterium diphtheriae causes
cutaneous diphtheria (Velat sore/Barcoo rot) with nonhealing ulcers and infections in immunocompromised individuals
Presumptive test for Corynebacterium diphtheriae seen in agar
Brown-black colonies with gray-brown halo on Tinsdale agar
Media and nutrients for Corynebacterium diphtheriae
Tinsdale and Loeffler medium; requires cystine; no increased CO2 required
Tests for toxigenic strain identification in C. diphtheriae
ELEK immunodiffusion test, tissue culture, EIA, PCR, Schick skin test, Roemer test (Guinea pig virulence test)
Zoonosis and infections associated with cattle; causes diphtheria-like sore throat and pneumonia; linked to summer outbreaks and bovine mastitis
Corynebacterium ulcerans
Zoonosis and infections associated with sheep, goats, and horses; causes suppurative granulomatous lymphadenitis
Corynebacterium pseudotuberculosis
Bacteria that resemble colonies of C. diphtheriae; positive for urease and reverse CAMP test
C. ulcerans and C. pseudotuberculosis
Corynebacterium infections that is the colonizer of male genitourinary tract; causes prostatitis and non-gonococcal urethritis (NGU); positive CAMP, glucose, and sucrose fermentation
Corynebacterium glucuronolyticum
Part of the normal flora and is also seen in skin of hospitalized patients in inguinal, axillary, or rectal sites; also intravenous catheters
Corynebacterium jeikeium
Causative agent of septicemia, skin infections, malignancies, neutropenia, and infections in AIDS patients, catheters, prosthetic valves, CSF shunts
Corynebacterium jeikeium
Growth characteristics of Corynebacterium jeikeium
Enhanced growth with lipids (add Tween 80 or serum); negative nitrate and urease tests
Causative agent for septicemia, endocarditis, pneumonia, and lung abscesses in immunocompromised patients; positive for nitrate and urease tests
Corynebacterium pseudodiphtheriticum
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
Corynebacterium urealyticum
Characteristic finding in Corynebacterium urealyticum urine samples that is also seen in Proteus spp.
Struvite crystals
Causative agent of erythrasma (superficial, chronic pruritic reddish-brown macules on skin); diagnostic feature of coral red fluorescence under Wood lamp
Corynebacterium minutissimum
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
Listeria monocytogenes
Virulence factors of Listeria monocytogenes
Listeriolysin O (pore-forming toxin), Siderophores (iron acquisition), Phospholipase (WBC escape), E-cadherin (placental invasion), Internalin (induces phagocytosis), Act A (actin polymerization)
Diseases caused by Listeria monocytogenes
Systemic: Bacteremia; CNS: meningitis, encephalitis, brain abscess, spinal cord infections; Neonatal Listeriosis (Granulomatosis infantisepticum); Immunocompromised infections
Microscopic morphology short gram-positive bacilli occurring singly or in short chains
Listeria monocytogenes
Motility characteristics of Listeria monocytogenes
Tumbling motility in nutrient broth at RT (1-2 hours); Umbrella-like or inverted Christmas tree growth in SIM at 22-25°C
Cold enrichment for Listeria monocytogenes
Specimen stored at 4°C for weeks to months
Selective media for Listeria monocytogenes
PAL-CAM and McBride medium
Diagnostic test for Listeria monocytogenes causing conjunctivitis in rabbits
Anton test (positive for purulent conjunctivitis)
Positive tests for Listeria monocytogenes
Catalase, CAMP (block-type hemolysis), Voges-Proskauer, Esculin
Negative tests for Listeria monocytogenes
H2S and Urease
Causative agent of zoonosis in veterinarians, meat butchers, and fish handlers; causes erysipeloid or butcher’s cut
Erysipelothrix rhusiopathiae
Virulence factors of Erysipelothrix rhusiopathiae
Capsule, Neuraminidase, Hyaluronidase, Surface proteins
Microscopic and culture characteristics of Erysipelothrix rhusiopathiae
Gram-positive short bacilli forming long filaments; Alpha-hemolytic on BAP
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
Erysipelothrix rhusiopathiae
Zoonosis associated with cattle, sheep, dogs, cats, and pigs; Reverse CAMP positive
Arcanobacterium haemolyticum
Microscopic features curved Gram-positive rods with pointed ends and rudimentary branching
Arcanobacterium haemolyticum
Normal flora of vagina, GI tract, and mouth; pleomorphic and alpha-hemolytic on BAP
Lactobacillus acidophilus
Microscopic forms of Lactobacillus acidophilus
Pleomorphic: long chaining bacilli, coccobacilli, spiral forms
Positive CAMP test and its result
Streptococcus agalactiae; Arrowhead hemolysis with S. aureus
