Microbiological Quality Assessment and Characterisation of Salmonella SPP. Associated with Chicken from Different Live Bird Processing Outlets in Accra, Ghana.

Abstract

Live bird markets (LBM) are generally known as a storefront or open market slaughter operations that slaughter, dress, and trade dressed or live poultry on demand. Poultry meat is a major vehicle for foodborne pathogens (Salmonella, Campylobacter and E. coli O157:H7) responsible for more than half of the global burden of foodborne illnesses. The activities of theses live bird operators are scarcely monitored hence many of them do not conform to regulations, increasing the risk of microbial contamination. The aim of this study was to use molecular and culture-based methods to identify and quantify significant microbiological hazards and characterize Salmonella spp. associated with broiler carcasses and processing environment at live bird markets in the Greater Accra Region of Ghana. Samples (148) comprising of 60 broiler carcasses from LBM, supermarkets and cottage farms, and 33 bench-top swabs, 33 faecal samples and 22 rinse water samples from LBM were assessed for Aerobic Plate Count (APC), Staphylococcus aureus, E. coli and prevalence of Salmonella, Campylobacter and E. coli O157:H7 using standard culture-based methods. Presumptive Salmonella, Campylobacter and E. coli O157:H7 were confirmed with Oxoid Microbact. Salmonella isolates were further confirmed using Salmonella ompC gene amplification by conventional PCR. Traditional serological test was used in the determination of the serotypes of the confirmed Salmonella isolates. Biofilm formation ability of Salmonella isolates were determined using 96-well-plate-crystal violet assay. Lethal and sub-lethal concentrations of biocides were determined against Salmonella using the tube dilution method. Antimicrobial resistance (AMR) of Salmonella against 14 antibiotics was determined using disc diffusion assay and EUCAST breakpoints. Prevalence data for categorical variables were presented as frequencies and percentages of occurrences whereas One-way ANOVA was employed to test the significant difference between the means of the dependent (retail outlets, serovars, environmental samples and biocide concentrations) and independent variables (log10CFU, log10CFU reduction, pH, and AMR breakpoints) The mean microbial load (aerobic plate count, S. aureus and Salmonellae) on chicken carcasses from the live bird markets were significantly higher (P=0.0000) than those from the supermarkets and cottage farms except for E. coli counts, which was significant higher (P=0.0000) in the chicken samples from the cottage farms as compared to those from the supermarket and the live bird market. A total of 61% Salmonella prevalence was recorded for the chicken carcasses. The prevalence of Salmonella was also relatively higher in live bird market samples although none of the retail outlets was compliant with GSA standards. Nine non-typhoidal (S. Typhimurium, S. Enteritidis, S. Newport, S. Senftenberg, S. Agona. S. Infantis, S. Mississippi, S. Westhampton and S. Adelaide) and one typhoidal (S. Paratyphi B) Salmonella serotypes were identified from the carcass, faecal matter, bench surfaces and rinse water samples. The Salmonella serotypes isolated exhibited moderate to strong biofilm forming ability hence frequent and effective cleaning is required to prevent the formation of these biofilms. Biocide concentrations of 5% NaCl, 0.5% KOH, 0.5% Acetic acid, 3% Citric Acid and 1% H2O2 were able to cause an average of 4 log10CFU/ml reduction. Most (93%) of the isolates were multidrug resistant; showing resistance against 3 to 9 antibiotics. Especially towards the antibiotics commonly administered to the birds for prophylactic purposes such as amoxicillin-clavulanic, oxacillin, erythromycin acid and tetracycline. Some of the Salmonella isolates recorded resistance against 3rd generation cephalosporins and fluoroquinolones prescribed for the treatment of invasive non-typhoidal Salmonella (iNTS) and typhoidal Salmonella (TS) infections in humans. There is therefore the need for regulators to ensure the implementation of good agricultural and hygienic practices coupled with food safety awareness training for both processors and consumers of the chicken.