Prevalence of Salmonella in juvenile dogs affected with parvoviral enteritis.

Salmonellosis is a disease of major zoonotic importance and canine parvovirus is a potentially fatal cause of canine enteritis with a world-wide distribution. Persistent isolation of Salmonella during routine environmental sampling surveys of a hospital ward, reserved for the treatment of dogs with canine parvovirus infection, prompted investigation into a possible source. We hypothesised that dogs affected by canine parvovirus would have a higher prevalence of faecal salmonellae compared to an apparently healthy cohort. Seventy-four client-owned dogs naturally infected with canine parvovirus and 42 apparently healthy client-owned dogs were included in the study. This prospective, longitudinal, observational study was conducted over an 18-month period. Fresh faecal samples were collected from dogs aged 6 weeks to 9 months diagnosed with canine parvovirus infection and admitted for treatment, and from apparently healthy dogs presented for vaccination or routine hospital procedures. Faeces were submitted for the isolation, antimicrobial susceptibility testing and serotyping of salmonellae. The prevalence of faecal Salmonella shedding was 22% and 31% for the affected and apparently healthy dogs, respectively, which was not statistically different. No significant associations between Salmonella status and possible risk factors or continuous variables such as age, body weight and duration of hospitalisation were identified. All the Salmonella isolates (n = 32) were resistant to penicillin G, lincomycin and tylosin. Salmonellae from nine different serotypes were identified. The prevalence of Salmonella shedding in both groups was higher than that commonly reported, yet similar to those in previous reports on young dogs, shelter dogs or dogs fed a raw meat diet.

Prevalence of methicillin-resistant Staphylococcus aureus among large commercial pig herds in South Africa.

The prevalence of nasal carrier status of methicillin-resistant Staphylococcus aureus (MRSA) in pigs has been described elsewhere, but is unknown in South Africa. To address concerns that exist regarding the zoonotic risk that carriers pose to workers, the herd-level prevalence of MRSA was determined among 25 large (> 500 sows) commercial pig herds in South Africa, representing 45% of the large commercial herds in the country. From each herd, the nasal contents of 18 finisher pigs were sampled at the abattoir, pooled into three and selectively cultured to determine the presence of MRSA. A herd was classified as MRSA-positive if one or more of the three pooled samples cultured positive. Three of the 25 herds tested positive for MRSA, equating to a 12% herd prevalence (95% CI: 7% - 23%) among South African commercial piggeries. The prevalence of nasal MRSA carriers among large commercial pig herds in South Africa was low compared to what has been reported elsewhere and suggests a relatively low zoonotic MRSA risk to workers in South African commercial piggeries and abattoirs.

Comparison of two culture techniques used to detect environmental contamination with Salmonella enterica in a large-animal hospital.

Salmonellosis is a common healthcare-associated infection in large-animal hospitals, and surveillance for Salmonella is an integral part of comprehensive infection control programmes in populations at risk. The present study compares the effectiveness of two culture techniques for recovery of Salmonella from environmental samples obtained in a large-animal referral veterinary hospital during a Salmonella outbreak. Environmental samples were collected using household cleaning cloths that were incubated overnight in buffered peptone water (BPW). Aliquots of BPW were then processed using two different selective enrichment and culture techniques. In the first technique (TBG-RV-XLT4) samples were incubated at 43 °C in tetrathionate broth and then Rappaport-Vassiliadis broth before plating on XLT4 agar. The second technique (SEL-XLD) involved incubation at 37 °C in selenite broth before plating on XLD agar. Salmonella was recovered from 49.7% (73/147) of samples using the TBG-RV-XLT4 technique, but only 10.2% (15/147) of samples using the SEL-XLD method. Fourteen samples (9.5%) were culture-positive using both methods, and 73 (49.7%) were culture-negative using both techniques. There were discordant results for 60 samples, including 59 that were only culture-positive using the TBG-RV-XLT4 method, and one sample that was only culture-positive using the SEL-XLD method. Salmonella was much more likely to be recovered using the TBG-RV-XLT4 method, and there appeared to be five times more false-negative results using the SEL-XLD technique. Environmental contamination with Salmonella may be underestimated by certain culture techniques, which may impair efforts to control spread in veterinary hospitals.