Evaluation and histological examination of a Campylobacter fetus subsp. venerealis small animal infection model.

Bovine genital campylobacteriosis (BGC), caused by Campylobacter fetus subsp. venerealis, is associated with production losses in cattle worldwide. This study aimed to develop a reliable BGC guinea pig model to facilitate future studies of pathogenicity, abortion mechanisms and vaccine efficacy. Seven groups of five pregnant guinea pigs (1 control per group) were inoculated with one of three strains via intra-peritoneal (IP) or intra-vaginal routes. Samples were examined using culture, PCR and histology. Abortions ranged from 0% to 100% and re-isolation of causative bacteria from sampled sites varied with strain, dose of bacteria and time to abortion. Histology indicated metritis and placentitis, suggesting that the bacteria induce inflammation, placental detachment and subsequent abortion. Variation of virulence between strains was observed and determined by culture and abortion rates. IP administration of C. fetus subsp. venerealis to pregnant guinea pigs is a promising small animal model for the investigation of BGC abortion.

An improved method for RNA extraction from carcass samples for detection of viable Escherichia coli O157:H7 by reverse-transcriptase polymerase chain reaction.

AIMS: To develop a rapid RNA extraction procedure for maximizing bacterial RNA yield from carcass samples with low abundance of Escherichia coli O157:H7 without pre-enrichment. METHODS AND RESULTS: Nontarget bacterial cells were added to the sample prior to RNA extraction, facilitating the co-precipitation of target RNA along with nontarget RNA and thus enhancing the recovery. This method was developed using a serial dilution of log phase target cells (E. coli O157:H7), combined with a high number of nontarget cells (E. coli K12). Cells were lysed by a bead beating method followed by RNA purification using a commercial kit. A reverse-transcriptase PCR assay for the detection of rfbE gene in E. coli O157:H7 was used to demonstrate that the procedure increased the recovery of amplifiable RNA target with a detection limit of approximately 63 CFU ml(-1) in cultures and 27.5 CFU ml(-1) in carcass liquor. CONCLUSIONS: An RNA extraction procedure was developed to detect low numbers (<30 viable cells ml(-1)) of E. coli O157:H7 in carcass liquor without pre-enrichment. SIGNIFICANCE AND IMPACT OF THE STUDY: This method could be applied for the detection of E. coli O157:H7 in low abundance on carcasses where rapid detection and early intervention is essential for safety in the livestock industry.

Two outbreaks of type C and type D botulism in sheep and goats in south Africa.

Two outbreaks of botulism in sheep and goats are described; in one, 329 out of 900 sheep in a feedlot died within 9 d of the onset of the disease and in the other, 100 sheep and goats out of 330 succumbed over a period of about 3 weeks. Animals were found dead or died suddenly, without exhibiting clinical signs. Others stood with lowered heads and showed drooling of saliva or a stiff gait. Paresis and/or paralysis were frequent signs in the terminal stages of the disease. Gross lesions such as the accumulation of fluids in body cavities, pulmonary oedema, foam in the trachea, epicardial haemorrhages and congestion of the mucosa of the small intestine, suggestive of heart failure, were present in animals from both outbreaks. Botulism was confirmed via the mouse toxicity test, by the demonstration of Type C and Type D toxins in the feed and intestinal contents of sheep from the first outbreak and Type D toxin in intestinal contents of sheep from the second. The clinical signs and macropathology in the outbreaks of botulism in sheep and goats in South Africa may resemble "krimpsiekte" and cardiac glycoside and ionophore poisoning, as well as other conditions causing heart failure.

Concurrent infection with Clostridium and Plasmodium in a captive king penguin Aptenodytes patagonicus.

Concurrent infection with Plasmodium relictum and Clostridium perfringens Type B was diagnosed in a king penguin (Aptenodytes patagonicus) that died in the National Zoological Gardens, Pretoria. Macro- and microscopic pathological changes were mainly due to C. perfringens. The relative significance of the two pathogens is discussed.

Studies on ultrastructure and cultivation of microorganisms associated with zebra nematodes.

Nematodes recovered from the hindgut of zebras were examined with scanning and transmission electron microscopy for microorganisms. Microorganisms were observed attached to the posterior extremities of two groups of nematodes, atractids and cyathostomes. Novel techniques were used to culture the microorganisms, and these included rinses to reduce contamination from hindgut flora and the design of the culture media. Electron microscopy revealed a flat bacterium not previously observed, as well as small rods and segmented filamentous bacteria. Culturing techniques resulted in isolation of a Propionibacterium species.