The prevalence of bacterial contamination with reference to Brucella abortus in slaughtered carcasses in selected abattoirs in the North West Province, South Africa

Abstract

Bacterial, and particularly Brucella abortus contamination in carcasses is a public health concern. Bovine brucellosis is a chronic disease of livestock caused by Gram negative coccobacilli bacteria of the genus Brucella and is a major threat to public health and animal trade in the world. The disease causes serious losses in the economy of the world due to late term abortions, weak animals and stillbirth. The aim of this study was to isolate Brucella abortus and other gram negative bacteria susceptible to contaminate bovine carcasses slaughtered in selected abattoirs in the North West Province, South Africa. In order to achieve this aim, abattoirs in Zeerust, Stella, Vryburg, Koster and Potchefstroom were selected in the North West Province, South Africa for the study. The following samples (Uterus, Placenta, Lymph tissues (mandibular and mammary lymph node) and Spleen were randomly collected for 5 days from each abattoir. Polymerase chain reaction (PCR) was used to confirm genetic profile from positive preliminary results obtained during the study. The results were found negative for Brucella when using the real time PCR tests. Brucella genomes IS711 and the universal primer were used. Results obtained revealed no positive Brucella abortus contamination from all samples analysed; however, other similar bacteria that could have led to confusion were isolated from some carcasses. Results of molecular identification showed that isolated strains were mostly Enterococcus spp (35%), Clostridium histolyticum (22%), Staphylococcus aureus (10%), Streptococcus australis (8%), Macrococcus spp. (4%), Bacillus spp. (4%), Lactococcus spp. (4%) Lactobacillus spp. (4%), Vagococcus spp. (2%), Peptostretococcus russellii (2%), and Aneurinibacillus spp. (2%). The presence of these bacteria in organs analysed might be due to poor hygiene in abattoir processes, possible contamination of water or other faecal material during processing. In addition, the molecular identification of strains revealed that were not yet fully identified and full similarities were not obtained from the Gene bank. The presence of these unidentified strains was an important finding as it raises questions on mutations, and appearance of new strains due probably to the movement of animals, populations and climatic changes. Despite the absence or non-isolation of positive Brucella abortus pathogens in samples analysed, the contamination of carcasses by other pathogenic gram negative bacteria constitutes a public health risk for meat consumers. There is a need of constant monitoring of animals sent to abattoirs particularly from non-tested farms. In addition there is a need to educate and train abattoir workers on basic hygiene practices to reduce the contamination of carcasses. Prevalence of Bovine brucellosis is still high in some areas, thus regular monitoring of abattoirs remains the key to food safety. Extensive surveys on longer periods should be done in advance. However, despite the interest in Brucella strains, other pathogenic strains remain a challenge for both abattoir workers and consumers. Monitoring, implementation of Hazard analysis and critical control point (HACCP) in abattoirs and identification, antibiotic susceptibility studies need to be done routinely to reduce risks of contamination but also of outbreaks provoked by new strains.