Corynebacterium Spp And Rhodococcus Equi

-small, pleomorphic, gram +

-in stained smears appear Chinese letter characters

-relatively slow growth in lab media

-most are catalase +, oxidase -,

-non spore forming

-pathogenic bacteria are non motile

-cause pyogenic infections

chinese letter characters of corynebacterium spp

-opportunistic pathogens

-pyrogenic organisms(with the exception of C. Bovis which can be isolated from teat canal of healthy cattle)

phagocytes

-cell wall lipid and an exotoxin(phospholipase D(PLD)) and Corynebacteial secreted protease 40(CP40)

PLD

strong immune response which may provide protection

diphtheria-toxin which the presence of in milk may have public implications

-urinary tract pathogens and produce urease

-also posses fimbriae for attachment to urogenital mucosa

-animals species affected and clinical signs may suggest a specific infection

-suitable specimens for the lab: pus, exudate, affected tissue, midstream urine

-direct examination of gram stained smears may reveal corynebacteria

-culture media: blood agar, McConkey and CNA incubated up to 5 days at 37C

-colonial characteristics

- presence of hemolysis

-absence of growth in McConkey, presences of growth in BAP and CNA

-typical corynebacterium polymorphism on gram stain

-biochemical tests

a chronic suppurative condition of sheep, goat, and rarely cattle caused by C. pseudotuberculosis with organisms surviving in the environment for several months

-skin wounds, arthropod bites, or dips

-ruptured abscesses

-hematogenous spread causes abscesses in internal lymph nodes

-abscessation and enlargement of superficial and internal lymph nodes

-goats usually develop superficial, subcutaneous abscesses usually in the head and neck

-ill-thrift and pneumonia may be present

-visceral form may not be detected antemortem

caseous lymphadenitis

around 3 months

-clinical (or postmortem) findings

-smears from lesions by gram stain

-isolation and identification of bacteria via submitted swabs to lab

-serological diagnosis:ELISA (individual and flock screen)

-interferon-gamma test as flock screen

susceptible to many antimicrobials but therapy is usually ineffective due to intracellular survival ability of bacteria and inability of drugs to penetrate into abscesses

-import animals from countries/states/flocks free of caseous lymphadenitis

-animals should be subjected to pre-importation screening tests such as ELISA

-imported animals should be quarantines up to 3 months

-infected animals should be slaughtered

-contaminated buildings and equipment should be disinfected

-vaccines available

- slow and chronic either lymphangitis of lower limbs or abscessation of pectoral region(also called pigeon fever)

-C. pseudotuberculosis in horses and rarely in cattle

-prevalent in fall and early winter

skin wounds, arthropod bites or contact of infected animals

ulcerative lymphangitis

ulcerative lymphangitis

-lymphatic vessels swollen and firm with nodules forming along their length

-edema develops in affected limbs and ulcerated nodules exude a thick odorless, greenish blood-tinged pus

based on isolation and identification in the lab

-systemic antimicrobials may be combined with topical Tx

- affected animals should be isolated and contaminated areas disinfected

C. renale- which may be isolated from healthy cattle vulva, vagina and prepuce

stress of parturition and short urethra in cow may predispose to infection

Bovine pyelonephritis

-ascending infection from bladder to ureters can result in pyelonephritis with chronic infections possibly leading to extensive renal damage

-fever, anorexia and decreased milk production

-restlessness and kicking in the abdomen may indicate renal pain

-dysuria and blood tinged urine are present

-clinical signs may suggest UTI

-red blood cells and protein are present in the urine

- thickened ureter and enlarged kidneys may be detected by renal palpation and or ultrasonography: unilateral

-culture of C. renale frome urine is confirmatory

-antimicrobial tx based on susceptibility test, should start early for at least 3 weeks

-penicillin is usually good choice for high excretion in urine

-caused by C. renale

-characterized by ulceration around prepucial orifice with a brownish crust developing over the lesion

-similar lesion may happen on the vulva of ewes

-castrated sheep more prone

-untreated cases may progress to total occlusion of preputial orifice

hydrolyizing urea into ammonia

high urea level in the urine due to high protein intake

ulcerative balanoposthitis

-gram positive rods or cocci

-salmon-pink, mucoid, non-hemolytic colonies

-aerobic, non motile

-CAMP test positive

-major respiratory pathogen of foals

Rhodococcus equi

-one of the most common causes of pneumonia in folas

-generally acquired by inhalation of dust

-may be present in high number in horse feces

-environmental influences-dry weather, poorgrass coverage

-high foal density

-only young foals susceptible

-ability to survive and multiply in macrophage

-virulence is principally associated with a large??(not on slide)

-encodes several proteins most important VapA

-only equine isolates have VapA gene

-capsular polysaccharides, mycolic acids and exoenzymes

-usually less than 4 weeks old foals

-sudden onset of fever

-anorexia

-signs of bronchopneumonia

-could be insidious in 2-4 month old foals

-coughing, dyspnea, weight loss, exercise intolerance

-loud, moist rales on auscultation

Rhodococcus equi- suppurative bronchopneumonia

-differentiating lower respiratory trac infections problematic

-WBC, fibronegen, radiography, ultrasonography,

-bacterial culture from tracheobronchial aspirate

-salmon color mucoid colonies on BAP, CAMP test

-PCR tests

-combination of oral rifampin and a macrolide for up to 10 weeks

-severely affected foals have poor prognosis

-response to therapy monitored by radiography/ultrsonagrophy and plasma fibrinogen

-supportive therapy: rehydration and bronchodilatotory agents or expectorants

-vaccines not aailable

-screening of foals twice a week clinical examination

-prevention of dust ihalation

-limit the foal density

-limited time spent indoor

-foaling at pasture may reduce the occurence

-passive immunization-hyperimmune plasma

-chemoprophylaxis-conflicting evidence and danger or resistance

-development of active immunization highly needed(aka vaccine)