Week 4 Corynebacterium, Listeria, Rhodococcus

• Small, short, pleomorphic Gram-positive rods

• “Chinese letter patterns

• Cell wall contains meso-diamino-pimelic acid (DAP) arabinogalactan, mycolic acid (also for myobacteria and nocardia)

• Non-sporulating

• Non-motile

• Aerobic or facultatively anaerobic

• Aerobic or facultatively anaerobic o Fermentative metabolism under certain conditions
  
  

changes in nomenclature

Previously classified as Corynebacterium

Corynebacterium species

main virulence factors of pathogenic Corynebacterium spp and rhodococcus equi in vet med

Main dx caused by major pathogenic Corynebacterium spp and rhodococcus equi to vet med

C. pseudotuberculosis

• caseous lymphadenitis

• ulcerative lymphadenitis

• mastitis

C. Bovis

• pyelonephritis

• mastitis

C. Diptheria

• respiratory diptheria & cutaneous diptheria

• Prototype A-B toxin

• Diptheria toxin

• selective media

C. jeikeium

• opportunistic infection to immunocompromised

• multiple ATB resistance

• Carriage on skin

C. urealyticum

• UTI

• urease hydrolyze urea

• mitis- black with gray periphery

• gravis- large gray

• intermedius- small dull gray to black

3 morphologic type of diptheriae on tellurite containing media

properties of the morphology

cystinase

Produce ____ on tinsdale medium

C renale

shows casein digestion on milk agar

R. equi, C. renale

Cell wall containstwo bacteria give an enhancement of the effect of the staphylococcal beta-hemolysin.

C. pseudotuberculosis

inhibition of the effect of the staphylococcal hemolysins

1. subcutaneous test

2. intracutaneous test

In vivo test

1. elek’s gel precipitation test

2. tissue culture test

in vitro test

• remain viable for 2-3 weeks at 25-30

• destroyed by heat

• resistant to light, desiccation/freezing

• easily destroyed by antiseptics

Corynebacterium prevention and control

• penicillin, erythromycin

• supportive therapy

• antitoxin

corynebacterium treatment and immunization

Listeria

• medium, non branching, short gram positive rods, non spore forming and non acid fast

• singly in a short chain, no capsule

• catalase +

• oxidase -

• motile

1. L monocytogenes

2. L. ivanovii

3. L innocua

3 pathogenic species

L. monocytogenes

most important pathogenic

• soil, silage, sewage effluent and stream water

• asymptomatic fecal carriers

habitat of listeria

• soil contamination and ingestion of contaminated feed

• silage dx = listeriosis

listeria transmission

virulence factor of listeria

main host and dx syndromes of pathogenic listeria species

Septicemic form

Listeria dx that attacks monogastrics and neonates

listerial septicemia

Listeria dx that attacks chinchillas

septicemia in neonates

Listeria dx that attacks horses

1. encephalitis form- circling disease, most common form in cattle (subacute to chronic)

2. abortion- 7months cattle 12 weeks in sheep

3. conjunctivitis- contaminated silage

Listeria dx that attacks Ruminants

L. monocytogenes

CAMP test with S. aureus enhancement of the effect of the staphylococcal beta-haemolysin by ____ but not by L. Ivanovii

L. ivanovii

Cam test with R. equi no rxn with L monocytogenes and enhancement of haemolysis by

• poor quality silage should not be fed to pregnant woman

• silage feeding should be discontinued if outbreak of listeriosis is confirmed

• feeding method with min direct ocular contact

• at pasture, reduced the risk by feeding through than the frround

• vaccination

prevention and control of listeria

• ATB oxytetracycline/penicillin

• b lactams, macrolides, tetracyclines, sulfonamides, chloramphenicol

• submission for culture and ATB sensitivity testing

• NSAID

• cephalosporins and fluroquinolones are not active

Tx of listeria

Rhodococcus

• gram +, aerobic, coccus/rods

• capsulated

• soil —> contaminated with horse and farm animal

Rhodococcus equi

• Previous name: Corynebacterium equi

• human opportunistic pathogen in immunocompromised humans.
  

R. equi virulence determinants

R.. equi dx

• susceptible to erythromycin and extended spectrum macrolides, rifampin, fluoroquinolones, aminoglycosides, glycopeptides, amp-sulbatumol and imipenem

• •2/3rd are susceptible to clindamycin, chloramphenicol, tetracyclines, and trimethoprim-sulfamethoxazole

• resistant in vitro penicillin and cephalosporins

• avoid B-lactam
  

R. equi treatment