Comparison of antimicrobial susceptibility testing of Campylobacter spp. by the agar dilution and the agar disk diffusion methods.

The correlation and the level of agreement between the standardized agar dilution and the agar disk diffusion methods for antimicrobial susceptibility testing of Campylobacter were investigated. A high-level agreement between the two methods was evident for aminoglycosides and fluoroquinolones, while a low-level agreement was observed for other antibiotics.

Evaluation of Pasteurella multocida isolated from rabbits by capsular typing, somatic serotyping, and restriction endonuclease analysis.

The goal of this study was to characterize Pasteurella multocida isolated from rabbits. Five hundred and fifty-three apparently healthy rabbits were sampled for this study. Nasal swabs were collected from each rabbit for P. multocida isolation and identification. Isolates were further characterized by capsular and somatic antigens and genomic DNA fingerprinting. Thirty-nine P. multocida isolates were recovered from 553 rabbits (7%). Capsular typing was done by depolymerization of P. multocida capsule by Staphylococcus aureus hyaluronidase and by disc diffusion with mucopolysaccharidase enzymes (heparinase III, chondroitinase AC, and hyaluronidase). Thirty-one (79%) of the isolates were capsular type A, and 8 isolates (21%) had untypable (UT) capsules. The gel-diffusion precipitin test was used to determine the somatic type of P. multocida isolates. Nineteen isolates were somatic serotype 3 (49%), 12 were serotype 1 (31%), 1 was serotype 2, 2 were serotype 5, 2 were serotype 12 with a weak reaction to antiserum raised against serotype 7 (5%), and 1 was serotype 4. Two of the isolates (5%) were UT. Restriction endonuclease analysis of the DNA of the isolates revealed 7 distinct profiles by digestion with HindIII, and 12 profiles were obtained with HpaII, whereas digestion with EcoRI did not differentiate between any of the P. multocida DNA isolates studied. The DNA restriction endonuclease enzyme HpaII was found more useful for differentiating between DNA fingerprints of P. multocida rabbit isolates. However, no correlation between capsular type, somatic serotypes, and DNA fingerprints was seen in this study.

interactions between escherichia coli and Newcastle disease virus in chickens.

We investigated the interaction between Newcastle disease virus (NDV) and Escherichia coli in cell cultures, embryonated eggs, and 8-wk-old chickens. We measured the interactions on the basis of bacterial adherence and NDV hemagglutination titer in chickens, chicken embryos, and chicken embryo cell culture. Depending on the inoculation order of E. coli, a significant alteration of the growth of NDV was observed in both chickens and chicken embryos. When certain strains of E. coli were given before NDV exposure, the virus titers were lowered. In chickens, the mean virus titer was significantly (P < 0.05) lowered in the crop, the proventriculus, the gizzard, and the jejunum. However, there were no significant differences (P < 0.05) between the two groups for NDV titers in the duodenum, ileum, and cecum. In chicken embryos, when E. coli serotypes O78 and O119:B14 were inoculated before NDV exposure, the mean NDV titers were significantly (P < 0.5) lowered. However, there were no significant differences (P < 0.05) in NDV titer between the two groups when E. coli serotypes O78:K80:NM and O1ab:K NM were inoculated 24 hr before NDV exposure. When NDV was given prior to E. coli exposure, NDV titer was higher in both chickens and chicken embryos. In chickens, when NDV was given 48 hr before E. coli inoculation, NDV was detected in the proventriculus, gizzard, jejunum, ileum, and cecum, whereas no virus was detected in the control groups (NDV only). In the crop, NDV was detected at a significantly (P < 0.05) higher titer in the E. coli-inoculated group when compared with the control group that received NDV alone. In chicken embryos, virus titer was significantly (P < 0.05) higher when NDV was given 24 hr before E. coli inoculation for all three NDV strains used (Ulster and V4 strains). Adherence of E. coli to chicken embryo kidney (CEK) cells was significantly higher (P < 0.05) when the CEK cells were infected first with NDV and then by E. coli. The mean bacterial count per microscopic field in NDV-uninfected monolayers was eight compared with 112 for the NDV-infected monolayers. In approximately 10% of the fields in NDV-infected monolayers, the bacteria were too numerous to count.

Bacteria isolated from uterine washings from mares in the Sudan.

Uterine washes collected from 200 barren mares were examined at the Khartoum veterinary clinic during the period May 1977 to May 1978. A variety of bacteria was isolated from 77 per cent of the mares investigated. Thirty mares were treated by parenteral injection and intrauterine infusion of the appropriate antibiotics. Twenty-one of these mares conceived, of which 17 delivered normal foals and 4 had early embryonic deaths.