Plasmid profiles and antibiotic susceptibility patterns of bacteria isolated from abattoirs wastewater within Ilorin, Kwara, Nigeria

Background and Objectives: Waste water from abattoirs could harbour bacteria some of which are pathogenic. Therefore, this study aimed to assess the quality of wastewater from some abattoirs in Ilorin, Nigeria. Materials and Methods: The counts of viable bacteria, total coliform, faecal coliform, enterococci, S. aureus, P. aeruginosa and Salmonella/Shigella spp. of the wastewater was determined using selective media. The sanitary condition appraisal, antibiotic susceptibility test and plasmid profile of the isolates were assessed using standard methods. Results: The highest count of viable bacteria and total coliform obtained were 9.0 × 107 and 3.0 × 107 CFU/ml respectively. Faecal coliform and enterococcal count had the same highest value of 3.0 × 105  CFU/ml. The highest count of pathogenic bacteria: Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella spp. were 2.5 ×  108, 1.9 ×  107  and 3.0 × 104 CFU/ml respectively. The abattoirs sanitary scores ranged from 28.6-57.1%.  The isolates showed multiple antibiotic resis- tance (MAR) index ranging from 0.5-1.0. Plasmid curing with 0.1 mg/ml of acridine orange solution led to reduction in the MAR index of most of the Gram negative bacteria. Pseudomonas stutzeri was susceptible to all the antibiotics while Proteus vulgaris was resistant to all the antibiotics after curing. Most of the Gram negative bacteria isolated belong to the families Enterobacteriaceae and Pseudomonadaceae while the Gram positive bacteria belong to the families Staphylococcaceae, Enterococcaceae and Streptococcaceae. Conclusion: It was concluded from this study that wastewaters from the abattoirs were contaminated by bacteria with high MAR index. Most of these bacteria borne their antibiotic resistant factors in their plasmid.