Identification, bacterial load and antibiotic resistance profile of Enterobacteriaceae isolated from effluent from the three abattoirs in the city of Lubumbashi (DR Congo)

Abstract

Introduction. Slaughterhouses represent a strategic sector of the food chain in the Democratic Republic of the Congo. By supplying the meat consumed on a daily basis, they contribute to the food security of urban populations. However, slaughtering activities produce large volumes of liquid effluent containing blood, fats, organic debris and intestinal microorganisms. When discharged untreated into the environment, this effluent becomes a major source of biological pollution.

Objectives. The aim of this study was to identify the enterobacteria present in the effluents from three abattoirs, to quantify their load, to describe their distribution across the sites and to assess their susceptibility to antibiotics.

Materials and methods. This was a descriptive cross-sectional study conducted from 14 July 2025 to 14 September 2025. Eighteen samples were collected, at a rate of six samples per abattoir: the Lubumbashi Public Abattoir, the Mzée Grand Market Abattoir and the Kibwe Farm Abattoir. The analyses were carried out at the bacteriology laboratory of the Lubumbashi University Clinics. Isolation was carried out on MacConkey agar and CLED agar, whilst identification was performed using the Le Minor panel of five media: Kligler, urea-indole, Simmons’ citrate, lysine-iron and SIM. Antibiogram testing was performed by agar diffusion in accordance with the CLSI/EUCAST 2024 recommendations. The data were analysed using SPSS version 23. Qualitative variables were compared using the chi-squared test and quantitative variables using analysis of variance (ANOVA). The threshold for statistical significance was set at p < 0.05.

Results. Our results show that, out of 18 samples, six species were isolated: Salmonella typhi 12/18, Citrobacter freundii 12/18, Klebsiella pneumoniae 5/18, Escherichia coli 2/18, Klebsiella oxytoca 1/18 and Edwardsiella tarda 1/18. S. typhi and C. freundii were the most common, each accounting for 36.36 per cent. They were found exclusively at the public abattoir and the Mzée market abattoir, with six strains at each site. The Kibwe farm, meanwhile, had four different species, with K. pneumoniae being the most prevalent at 15.15 per cent. Bacterial counts revealed very high loads, particularly at the Kibwe farm: ranging from 130.10² to 290.10⁵ CFU/ml, with a mean of 1.97×10⁷ ± 1.06×10⁷ CFU/ml, p = 0.006. Mzée and Public had lower averages: 2.70×10⁴ and 2.81×10⁴ CFU/ml, p = 0.000. The ANOVA confirmed that the difference was significant. The resistance profile shows very high rates of resistance to beta-lactams. S. typhi: 100 per cent resistant to aztreonam and ampicillin, 92 per cent to cefotaxime. C. freundii: 100% resistant to aztreonam, piperacillin/tazobactam, cefotaxime and cefixime. K. pneumoniae: 100% re ly resistant to amikacin, cefotaxime, piperacillin/tazobactam, aztreonam and ampicillin. The MAR index is >0.2 for S. typhi (0.69), C. freundii (0.69) and K. pneumoniae (0.63). The main limitation of this study lies in the small number of samples analysed and the lack of molecular confirmation of the bacterial strains.

Conclusion. We therefore conclude that the effluents from the three slaughterhouses in Lubumbashi are heavily contaminated with multidrug-resistant Enterobacteriaceae. These results enable the risk of contamination to be assessed and should inform public health policy.

Keywords: Identification, enterobacteria.

Received Date: August 17, 2026

Accepted Date: September 09, 2026

Published Date: October 01, 2026

Available Online at: https://www.ijsrisjournal.com/index.php/ojsfiles/article/view/1012