Prevalence and antimicrobial profile of potentially pathogenic bacteria isolated from abattoir effluents in Bulawayo, Zimbabwe

The spread of pathogenic bacteria from food production processes has become a problem worldwide. Abattoir effluents are potential carriers of resistant pathogenic bacteria and could be contributing to the global spread of these strains in the environments. We investigated the prevalence and antimicrobial profiles of bacteria isolated from government (Abattoir 1) and private owned (Abattoir 2) abattoir effluents. A total of 300 effluent samples were collected from each abattoir. Total bacterial counts and antibiotic sensitivity profiles were determined. The total bacterial counts in effluents were high for both abattoirs, ranging from 7.83 to 5.81 log CFU/mL. Significant differences were observed (p < 0.05) between bacterial counts of abattoir 1 and 2 at all sampling sites A, B and C. However, bacterial counts for Abattoir 1 were significantly higher than those for Abattoir 2 at sampling sites A and B and on the contrary total bacterial counts for Abattoir 1 were significantly lower at sampling site C. Sampling site A had the most bacteria (average: 7.55 log CFU/mL) while site C had the least bacteria (average: 6.32 log CFU/mL), suggesting that the processing could lower the discharged effluent's bacterial counts. Fifteen different potentially pathogenic bacteria were isolated from the effluent. Escherichia coli, Bacillus spp, Streptococcus pyogenes, Citrobacter freundii, Citrobacter spp, Klebsiella aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Salmonella spp, Staphylococcus aureus, Staphylococcus coagulase negative, S. enteritidis, Staphylococcus epidermidis and Staphylococcus intermedius. E. coli (23.33%) and Bacillus species (21.85%) were the most prevalent and Staphylococcus intermedius (1.30%) the least prevalent. Most bacterial isolates (58.71%) were highly resistant to antibiotics tested and this could be very dangerous if the effluent is released into the environment without treatment. Therefore, there is a need to evaluate current environmental, veterinary, and public health policies to monitor and produce safe effluents.