Concentrations of faecal coliforms, Escherichia coli, enterococci and Campylobacter spp. in equine faeces.

AIMS: To determine the concentration of Campylobacter spp. as well as faecal indicator bacteria; faecal coliforms, Escherichia coli and enterococci in the faeces of healthy adult horses in a sample of properties in the Canterbury region of New Zealand. METHODS: The faeces of healthy adult horses (n=59), including ponies, pleasure horses and Thoroughbreds, were collected from eight properties around Christchurch, New Zealand. The faeces were analysed for concentrations of Campylobacter spp and faecal indicator bacteria; faecal coliforms, Escherichia coli and enterococci. The presence of other animals on the properties sampled as well as the age, feed and health of the horses at the time of sampling was recorded. RESULTS: Enterococci and faecal coliforms were isolated from all samples, and E. coli was isolated from 58/59 samples. Mean concentrations of faecal coliforms and E. coli did not differ between properties, but there was a significant difference in mean concentration of enterococci between properties. Campylobacter spp. were detected in two faecal samples with one isolate being determined by PCR analysis to be a thermotolerant Campylobacter species, the other C. jejuni. CONCLUSIONS: This is the first known report quantifying the concentration of Campylobacter spp. present in healthy adult horses in New Zealand. The presence of equine faecal material in water could elevate concentrations of faecal bacteria and therefore needs to be considered as a source of water contamination. The access of horses to waterways and coastal environments may also need to be restricted to prevent transmission of faecal indicator bacteria and potentially zoonotic agents.

Leaching of Escherichia coli from sheep faeces during simulated rainfall events.

UNLABELLED: Sheep faeces are known to harbour to a high concentration of microbial indicators and pathogens. These can be released under rainfall and may result in contamination of waterways, potentially leading to illnesses in humans. A study was designed to determine the concentration of Escherichia coli released from fresh and aged (0-21 days old) ovine faeces. In summer and autumn, ovine faeces were subjected to simulated rainfall and the resultant run-off collected. Escherichia coli were enumerated in both the run-off and the faeces. In autumn total suspended solids (TSS) and turbidity were also monitored in the run-off. This study provides quantitative evidence that E. coli in aged sheep faeces is mobilized by rainfall events. Simulated rainfall events released between 10(3) and 10(4) CFU E. coli ml(-1) throughout the 21 days. TSS or turbidity with fresh faeces may be indicative of microbial contamination, but from aged faeces, this may not be the case. SIGNIFICANCE AND IMPACT OF THE STUDY: This study confirms that faecal bacteria can be released from fresh and aged ovine faeces under stimulated rainfall. It demonstrates that aged faeces remain a source of faecal bacteria, which under rainfall can release the bacteria and result in pollution of waterways. This study aids in our understanding of the potential impact of grazing sheep on the microbial quality of surface waters in NZ.

Survival of Escherichia coli, enterococci and Campylobacter jejuni in Canada goose faeces on pasture.

Freshly excreted Canada goose faeces pose a public health risk as they contain pathogenic microorganisms. Accordingly, a study was carried out on the growth and survival of resident indicator bacteria (enterococci and Escherichia coli) and inoculated Campylobacter jejuni in freshly excreted faeces over summer and winter. Canada goose faeces were collected, mixed thoroughly and inoculated with 108 g⁻¹ C. jejuni. The faeces were mixed again before making the Canada goose dropping. The simulated goose droppings (N = 70) were placed on pasture, and the concentrations of E. coli, enterococci and the pathogen, C. jejuni, were monitored. In summer only, the molecular marker of E. coli LacZ and the avian-associated bacteria E2 was also monitored. Results of the survival study indicated that significant growth of enterococci and E. coli occurred in summer, before concentrations decreased to less than 15% of the original concentration (day 77) for enterococci and 0.01% for E. coli. LacZ followed a similar pattern to E. coli, while the E2 marker dropped to below 0.1% of the original concentration within 4 days. In winter, enterococci grew slightly, while no growth of E. coli occurred. In both summer and winter, C. jejuni was rapidly inactivated. This research highlights the ability of bacterial indicators to replicate and survive in the environment when harboured by avian faeces, and the limited risk aged Canada goose faeces pose as an environmental source of Campylobacter spp.

A survey of enteric bacteria and protozoans in fresh bovine faeces on New Zealand dairy farms.

AIMS: To determine the counts and/or prevalence in fresh bovine faeces of Escherichia coli, enterococci, Campylobacter, Salmonella, shiga toxin-producing E. coli (STEC), Giardia and Cryptosporidium, as inputs to numerical models designed to estimate microbial loadings on pasture grazed by cattle in New Zealand. METHODS AND RESULTS: In each season over one year, samples of freshly deposited bovine faeces were collected from four New Zealand dairy farms (n = 155), and enumerated for E. coli, enterococci, Campylobacter, Giardia and Cryptosporidium. They were also tested for the presence of Salmonella and STEC. The overall median bacterial counts (g(-1) wet weight) were E. coli- 5.9 x 10(6); enterococci - 1.3 x 10(4); Campylobacter- 3.9 x 10(5). All counts were highly variable within and between samplings, and few seasonal or regional patterns emerged. However, mean Campylobacter counts were consistently higher in spring. No Salmonella spp. was detected, and only two samples were positive for STEC. Cryptosporidium and Giardia were isolated from 5.2% and 4.5% of the samples, respectively, yielding low numbers of (oo)cysts (1-25 g(-1) and 1-17 g(-1), respectively). CONCLUSIONS: Fresh bovine faeces are a significant source of E. coli, enterococci and Campylobacter on New Zealand pastures, although numbers are likely to vary markedly between faecal samples. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides the first significant set of indicator and pathogen counts for one of the largest sources of faecal contamination of natural waters in New Zealand, and will be used to model these inputs.

The prevalence and characterisation of Cryptosporidium spp. in beef abattoir water supplies.

The prevalence of Cryptosporidium spp. in 50 l samples of water used to wash beef carcasses at (a) an abattoir with a borehole water (BH) supply (n = 46) and (b) an abattoir with a river water (RW) supply (n = 48) was determined. In addition, a 100 l water sample and post-wash carcass samples (n = 24) were collected from the RW supply on a single day in July. Cryptosporidium spp. was detected in 0% and 26.1% of samples from the BH and RW supply abattoirs, respectively, with oocyst concentrations ranging from 0.02 to 8.6/l. Cryptosporidium spp. was not isolated from post-wash beef carcasses, while it was detected in water samples from that day at a concentration of 0.06 oocysts/l. The species of 3/5 isolates were identified as C. parvum, and the remaining were C. andersoni. This study has demonstrated that water used to wash beef carcasses can be contaminated with Cryptosporidium of human health importance and is a potential source of carcass contamination.

Prevalence and characterisation of Cryptosporidium species in cattle faeces and on beef carcases at slaughter.

Cattle are known reservoirs and asymptomatic excretors of Cryptosporidium, a protozoan parasite that causes severe and protracted diarrhoea in people. The incidence of Cryptosporidium was investigated in 288 matched samples taken from beef carcases of 1 g samples of faeces retrieved immediately after de-legging, 25 cm2 samples of beef excised from the rump of uneviscerated carcases, and 25 cm2 samples of beef excised from the brisket area of eviscerated carcases. Cryptosporidium species were detected in 21 of the faecal samples after salt flotation and immunofluorescent microscopy. The species isolated from the positive samples were identified by restriction fragment length polymorphism and PCR as Cryptosporidium andersoni (54.5 per cent) and Cryptosporidium parvum genotype 2 (45.5 per cent). In the faecal samples, there was a significantly higher prevalence of the parasite in samples taken in summer (May to July) and winter (November to January) than in spring or autumn. No Cryptosporidium species were recovered from any of the beef samples.

The effect of thermal treatments on the viability and infectivity of Cryptosporidium parvum on beef surfaces.

AIMS: The aim of this research was to examine the effect of thermal treatments on the viability and infectivity of Cryptosporidium parvum oocysts attached to a beef surface. METHODS AND RESULTS: This study examined the effects of heat treatment (60 or 75 degrees C) on the viability of C. parvum oocysts inoculated onto the surface of beef muscle estimated by vital dye assay. The infectivity of the oocysts was assessed against monolayers of HCT-8 cells. At 60 degrees C viability of the oocysts decreased from 100% at T0 to 64.2% at T60. At 75 degrees C the viability of the oocysts decreased from 100% at T0 to 53.7% at T15 and finally to 11.2% at T60. Oocysts were rendered noninfective against monolayers of HCT-8 cells following treatments of 60 degrees C/45 s and 75 degrees C/20 s. CONCLUSION: The washing of carcasses with hot water and standard thermal treatments is sufficient to kill C. parvum on beef. SIGNIFICANCE AND IMPACT OF THE STUDY: This study found that relatively mild heat, currently used to decontaminate and heat treat beef carcasses and to cook meat products, is capable of inactivating C. parvum.

Effect of a commercial freeze/tempering process on the viability of Cryptosporidium parvum oocysts on lean and fat beef trimmings.

Lean and fat beef trimmings (25 cm(-2)) were inoculated with approximately 250,000 Cryptosporidium parvum oocysts, placed in commercial packages (28 kg boxes) and subjected to normal commercial processes i.e. blast frozen (to -20 °C within 60 h), stored (-20 °C, 21 days), tempered (48 h at -3 °C), and held at 0 °C for 10 h. Inoculated areas were then excised, pulsified (30 s in 50 ml PBST), and centrifuged (2500×g, 15 min). The resultant pellet was resuspended in 10 ml water and subjected to immunomagnetic separation and viability dye assay. Following the commercial freeze/tempering process the viability of the oocysts had decreased from 90.6% viable in the working stock suspension to 7.17% and 9.46% viable on lean and fat trimmings, respectively. The results of this study indicate that if C. parvum oocysts were present on beef trimmings their viability would be substantially reduced as a result of the freeze/tempering process.