Antibiotics Susceptibility Profile of Listeria species Isolated from Untreated Abattoir Wastewater in Akinyele, Ibadan, Nigeria and Its Implication on Public Health

Introduction: The demand for meat to meet the need of increasing human population has led to increase in the abattoir activities. Untreated abattoir wastewaters which may constitute a public health threat due to the possibility of transmission of pathogens to humans are constantly being discharged into water bodies. Listeria is an emerging pathogen that is commonly associated with food infection and has been found to survive in water.

Aim: This study was carried out to determine the occurrence and antibiotic resistant pattern of Listeriaspecies isolated from abattoir wastewater in Akinyele, Ibadan.

Materials and Methods: Wastewater samples were collected from the slaughter slab and drainage channels between May and June, 2015. Listeria species were isolated using Listeria Selective Agar Base with Listeria Selective Supplement and identification of the isolates was done using conventional methods. Antimicrobial susceptibility testing was carried out using the Kirby-Bauer disk diffusion assay using single antibiotic disks including ampicillin, streptomycin, chloramphenicol, amoxicillin/clavulanate, ceftriazone, cloxacillin, ciprofloxacin, ofloxacin, tetracycline and trimethoprim/sulfamethoxazole.

Results: A total of 82 Listeria spp. were isolated comprising 58.5% and 41.5% from the slaughter slab and drainage respectively; all the isolates were resistant to ampicillin while 86.6%, 68.3% and 65.5% were resistant to ceftriaxone, amoxicillin/clavulanate and tetracycline respectively. In addition, 12.2% of the total isolates were resistant to a combination of six antibiotics (ampicillin, tetracycline, amoxicillin, ceftriazone, streptomycin, and trimetoprim/sulfamethozaxole) while only one isolate was resistant to eight or more antibiotics.

Conclusion: This study revealed that the Akinyele abattoir wastewater is a potential medium for the transmission of multi-drug resistant bacteria to humans. Hence, adequate measures should be put in place for the treatment of the abattoir wastewater before discharge into the environment.