Corynebacterium equi in cattle and pigs

Summary The cervical lymph nodes of pigs, the retropharyngeal and submandibular lymph nodes of cattle and faecal samples from both animal species were examined for the presence of Corynebacterium equi. The organism was recovered from 19 (35 per cent) of 54 porcine cervical lymph nodes and from 0 of 54 bovine retropharyngeal and submandibular lymph nodes. Fifteen (50 per cent) of 30 bovine faecal and 11 (35 per cent) of 31 porcine faecal samples yielded C. equi.     

Corynebacterium equi in cattle and pigs

Summary

The cervical lymph nodes of pigs, the retropharyngeal and submandibular lymph nodes of cattle and faecal samples from both animal species were examined for the presence of Corynebacterium equi. The organism was recovered from 19 (35 per cent) of 54 porcine cervical lymph nodes and from 0 of 54 bovine retropharyngeal and submandibular lymph nodes. Fifteen (50 per cent) of 30 bovine faecal and 11 (35 per cent) of 31 porcine faecal samples yielded C. equi.     

A cat with Corynebacterium equi lymphadenitis clinically simulating lymphosarcoma.

A cat with granulomatous lymphadenitis due to Corynebacterium equi is described. Clinically the cat was diagnosed as having lymphosarcoma. Bacteria were cultured from the lymph nodes.     

Antibody to equi factor(s) in the diagnosis of Corynebacterium equi pneumonia of foals.

Antibody to equi factor(s) in cases of Corynebacterium equi pneumonia in foals was detected using C. pseudotuberculosis exotoxin sensitized calf red blood cells. The test was standardized using antitoxin produced in rabbits by injection of equi factor(s). All sera from ten foals with culture-diagnosed C. equi pneumonia had antibodies to equi factor(s) (titre range 8-256, mean 74.0) and nine sera from 11 foals with suspected C. equi pneumonia also showed antibodies (titre range 4-512, mean 136.4). Two of five pneumonia foals with transtracheal aspirate cultures not yielding C. equi had such antibodies. Fifty-eight of 59 control horse sera had no antibodies; the one positive serum came from a foal on a farm where C. equi pneumonia was endemic. By contrast only five of 15 foals with experimentally-induced C. equi pneumonia had antibodies to equi factor(s), probably because the acute nature of the disease produced did not mimic the chronic course of the natural disease. Antibody to equi factor(s) can be used in the diagnosis of naturally-occurring corynebacterial pneumonia in foals.     

Corynebacterium equi in the gastrointestinal tract of ruminants

Corynebacterium equi has been recovered from the gastrointestinal tract of sheep and cattle. It can be found in all parts of the gut, and around 80% of animals have the organism in one or more intestinal sites.C. equi could be detected in the faeces of sheep which were kept caged and free from recontamination by the organism.     

Epidemiological survey of Corynebacterium equi infections on five Ontario horse farms.

Corynebacterium equi was cultured from manure or soil on five horse-breeding farms in Ontario at monthly intervals on three occasions during the summer of 1982. The organism was widespread. Contamination by C. equi of the loafing paddock and pasture areas was significantly greater in a farm established 30 years than in two established for four and six years and there was a significant correlation between the C. equi burden in stables, paddocks and pastures and the length of use of the five farms for horses. In all farms, numbers of C. equi in pasture soil exceeded numbers in fresh manure, suggesting that environmental multiplication of the organism might occur. A farm with an endemic C. equi pneumonia problem differed significantly from the other four farms, where disease was not endemic, in the larger number of C. equi isolated in the stable area. By contrast the farm with a C. equi pasture soil burden significantly heavier than on all other farms had no deaths due to C. equi pneumonia. There was a correlation (r = 0.78, p = 0.061) between the number of cases of C. equi pneumonia on the farms and numbers of C. equi in the area of the stables, but not on the paddocks or pastures. About two-thirds of randomly chosen isolates from the farms belonged to the three capsular serotypes most commonly found in pneumonic foals.     

Cellular and humoral immune response of foals to vaccination with Corynebacterium equi.

Transformation of peripheral blood lymphocytes from pony foals vaccinated and subsequently infected with Corynebacterium equi was studied. Three foals were vaccinated on two occasions using a formalinized C. equi vaccine with aluminum hydroxide as an adjuvant. Three nonvaccinated foals served as controls. Foals were challenged intratracheally with 9 x 10(9) C. equi six weeks after the initial vaccination.Foals survived this infection for one to two weeks. Significant lymphocyte transformation in response to C. equi antigens was detected in two vaccinated foals at the third week after initial vaccination and in all vaccinated animals at the fifth week. No statistically significant transformation was seen in nonvaccinated foals before infection. Vaccinated and nonvaccinated foals showed responsive lymphocytes following challenge. Vaccination offered no obvious protection against experimental challenge but this failure was probably due to an excessive infective dose of organisms. Low levels of humoral antibodies were detected in some challenged foals. The pathological changes in the lungs of infected animals were comparable with, but more fulminating than, changes observed in the natural disease.     

The susceptibility of isolates of Corynebacterium equi to antimicrobial drugs

Fifty-one isolates of Corynebacterium equi recovered from pigs and horses belonging to two capsular serotypes were tested for susceptibility to antimicrobial agents. No clear differences were detected in sensitivity between isolates of different sources or serotypes. All isolates were sensitive to <0.25 μg/ml of erythromycin and gentamicin. The following minimum inhibitory concentrations (MICs) of antimicrobial agents were determined for ≤90% of isolates: methicillin >16 μg/ml, clindamycin 1–2 μg/ml, tobramycin ≤1 μg/ml, cephalothin 8–64 μg/ml, kanamycin 2–8 μg/ml, amikacin ≤1–2 μg/ml, penicillin 2–≤4 μg/ml, ampicillin 2–8 μg/ml, trimethoprim-sulfa 4/76–32/608 μg/ml tetracycline 1–4 μg/ml and chloramphenicol 8–16 μg/ml.     

Treatment of Corynebacterium equi pneumonia of foals: a review

Combined antimicrobial drug treatment was recommended for foals with Corynebacterium equi pneumonia. The preferred combination is orally administered erythromycin estolate (25 mg/kg of body weight, QID) plus rifampin (10 mg/kg, BID). Erythromycin estolate also can be combined for synergistic effect with sodium benzyl penicillin given IV (100,000 IU/kg, QID) or with ampicillin given IV (11 to 15 mg/kg, QID). A third choice is sodium benzyl penicillin IV with gentamicin IM (2.2 mg/kg, TID) or with kanamycin IM (10 mg/kg, QID). Gentamicin should be combined with penicillin G or ampicillin and not used for longer than one week without monitoring for nephrotoxicosis. Rifampin should be used only in combination with erythromycin or penicillin. Erythromycin or rifampin and gentamicin give antagonistic interactions in vitro. Chloramphenicol or trimethoprim-sulfamethoxazole may be effective if given in high doses but are not preferred drugs. Treatment response should be monitored clinically and radiographically and treatment should be continued for 2 weeks after the foal is clinically and radiographically normal.     

Clinical and radiographic findings in Corynebacterium equi pneumonia of foals

Thirty-nine foals with pneumonia were admitted to the Veterinary Medical Teaching Hospital at the University of California, Davis. Corynebacterium equi was recovered from each of them on bacteriologic culture of transtracheal aspiration specimens or lung specimens at necropsy. The foals were divided into 2 groups. Group I consisted of 20 foals that died because of C equi pneumonia and were subsequently necropsied. Group II consisted of 19 foals that were treated and discharged from the hospital. Radiography was performed on all foals. Clinical signs included increased respiratory rate, fever, cough, nasal discharge, increased bronchovesicular sounds over large airways, and wheezing over small airways. Highly significant differences were found in the mean respiratory rate (P less than 0.005) and temperature (P less than 0.001), recorded at admission, between the 2 groups; both factors were higher for group I. Hematology revealed leukocytosis with neutrophilia, monocytosis, and high plasma fibrinogen content in all foals. Significant differences were recorded in the mean total leukocyte count (P less than 0.05), mean neutrophil count (P less than 0.05), mean monocyte count (P less than 0.005), and mean fibrinogen value (P less than 0.05) between the 2 groups; values from group I were higher than those from group II. Although C equi was isolated alone from 25 of the tracheal aspirates and lung specimens, 14 cultures yielded multiple pathogens. At the time of initial examination, all foals had radiographic evidence of pneumonia. Pulmonary consolidation indicative of bronchopneumonia was identified in 31 of the 39 foals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Equine cell-mediated immune response to Rhodococcus (Corynebacterium) equi

A lymphocyte blastogenic assay was developed to serve as an in vitro correlate of cell-mediated immunity to Rhodococcus (Corynebacterium) equi (R equi) in the equine species. Lymphocytes obtained from a group of experimental ponies showed no response in cell culture to R equi heat extract or lysozyme extract antigens. Ponies were assigned to groups for experimental inoculation. Three ponies were inoculated subcutaneously with live R equi, 3 were given live R equi by intranasal and intratracheal routes, and 4 ponies were left untreated. Lymphocytes from all inoculated ponies had a mitogenic response to R equi antigens in lymphocyte blastogenic assays performed between the 7th and 40th days after inoculation. Lymphocytes from noninoculated control ponies remained unresponsive to R equi antigens. Delayed-type hypersensitivity reactions developed in all experimentally exposed ponies after intradermal administration of the R equi antigen preparations. In a 2nd phase of experimentation, blastogenesis assays were performed on lymphocytes from horses in herds with endemic R equi infections. Results indicated that many of the animals had significant (stimulation index greater than 2) cell-mediated responses to the bacterium, but there was no distinct correlation between the immune response and clinical history. These data indicated that cell-mediated immunity is involved in the interaction of the equine immune system with R equi.