Distribution of Enterobacteria in Ready-to-Eat Food in Cafeterias and Retail Food Outlets in Benin City: Public Health Implications

Background: The aim of this study was to determine the occurrence and antibiotic susceptibility profile of enterobacteria isolated from ready-to-eat foods within Benin metropolis, Nigeria.Methods: This was a descriptive study of 210 ready-to-eat food samples comprising fried rice, jollof rice, moi-moi, salad, oil beans, non-oil beans, and African salad obtained from roadside food vendors between January and June 2017. Isolation and identification of enterobacteria isolates were carried out using standard bacteriological and molecular methods. Antibiotic susceptibility profile was carried out using the disc diffusion method.Results: The mean mesophilic bacterial count expressed in log10 CFU/g from the ready-to-eat foods ranged from oil beans (4.3±0.52) to African salad (7.2±1.38). Escherichia coli count ranged between oil beans (1.8±0.16) and African salad (4.1±0.10). Salmonella species count ranged from non-oil beans (2.3±0.17) to African salad (5.2±0.09). Significant differences were observed from the population count of the ready-to-eat foods (p < 0.05). Bacterial isolates recovered from the ready-to-eat foods include Pseudomonas aeruginosa, Citrobacter freundii, Enterobacter cloacae, Salmonella enterica, Escherichia coli, Klebsiella oxytoca. The highest occurrence of the bacterial isolates was Escherichia coli 23(41.07%) while the least was Citrobacter freundii 3(5.36%) and Enterobacter cloacae 3(5.36%). The antimicrobial susceptibility profile of the bacterial isolates revealed that all bacterial isolates were 100% resistant to cefepime, ceftazidime, cefuroxime, ertapenem, and meropenem; with considerable sensitivity to kanamycin and gentamycin.Conclusion: The occurrence of these bacterial isolates in the foods constitutes public health risk to consumers as these pathogens have been associated with foodborne infections. Keywords: Antibiotic-resistant; Enterobacteria; Foodborne pathogens; Microbial quality; Public health; Street food

Effects of rinsing on Staphylococcus aureus load in frozen meats and fish obtained from open markets in Benin City, Nigeria

Background: Staphylococcus aureus is a ubiquitous bacterium present in the environment and one of the leading causes of superficial and deep infections. In the food industry, it is acclaimed to be globally responsible for several food-borne diseases. This study was designed to isolate methicillin-resistant S. aureus (MRSA) and determine the effect of rinsing on MRSA load in frozen meat and fish obtained from open market in Benin City.Methodology: Forty frozen meat samples (15 beef, 10 fish and 15 chickens) were randomly obtained from five markets in Benin City. The samples were analysed before and after rinsing using standard culture-based techniques to determine heterotrophic bacterial count, isolation of S. aureus, MRSA, and antibiotic susceptibility testing. Data were analysed using SPSS version 21 and Microsoft excel 2016, and association between variables were measured using Student’s t-test with a probability level of < 0.05.Results: The natural logarithm (LN) of heterotrophic bacterial count (CFU/g) before rinsing were 11.53±1.25 (beef), 11.16±0.95 (fish) and 11.42±1.58 (chicken), while the counts after rinsing were 2.70±0.45 (beef), 2.68±0.25 (fish) and 2.79±0.49 (chicken) (p<0.05). Sixteen of the 40 (40%) were positive for S. aureus, of which 4 (10%) were MRSA. Amongst the frozen meat evaluated in the study, beef had the highest frequency of S. aureus contamination (46.7%) followed by chicken (40.0%) and fish (30.0%). The profile of antibiotic resistance of S.aureus showed that they were least resistant to ciprofloxacin (6%) but showed high resistance to erythromycin (94%), amoxicillin/clavulanic acid (87.5%) and trimethoprim-sulfamethoxazole (81%). Multiple antibiotic resistance index of S. aureus was calculated to be 0.63.Conclusion: The findings in this study revealed that frozen foods could act as a vehicle for the dissemination of antibiotic-resistant bacteria (ARB) and potential health risks for consumers. Keywords: Staphylococcus aureus; antibiotic-resistant bacteria; MRSA; frozen meat; rinsing   French title:  Effets du rinçage sur les charge de Staphylococcus aureus dans les viandes congelées et les poissons obtenus sur les marchés ouverts de Benin City, Nigéria Contexte: Staphylococcus aureus est une bactérie ubiquitaire présente dans l'environnement et l'une des principales causes d'infections superficielles et profondes. Dans l'industrie alimentaire, il est reconnu pour être globalement responsable de plusieurs maladies d'origine alimentaire. Cette étude a été conçue pour isoler S. aureus résistant à la méthicilline (SARM) et déterminer l'effet du rinçage sur la charge de SARM dans la viande et le poisson congelés obtenus sur le marché libre de Benin City.Méthodologie: Quarante échantillons de viande congelée (15 bœuf, 10 poissons et 15 poulets) ont été obtenus au hasard sur cinq marchés de Benin City. Les échantillons ont été analysés avant et après le rinçage en utilisant des techniques de culture standard pour déterminer le nombre de bactéries hétérotrophes, l'isolement de S. aureus, le SARM et les tests de sensibilité aux antibiotiques. Les données ont été analysées à l'aide de SPSS version 21 et de Microsoft Excel 2016, et l'association entre les variables a été mesurée à l'aide du test t de Student avec un niveau de probabilité <0,05.Résultats: Le logarithme naturel (LN) du nombre de bactéries hétérotrophes (UFC/g) avant rinçage était de 11,53±1,25 (bœuf), 11,16±0,95 (poisson) et 11,42±1,58 (poulet), tandis que les comptages après rinçage étaient de 2,70±0,45 (bœuf), 2,68±0,25 (poisson) et 2,79±0,49 (poulet) (p<0,05). Seize des 40 (40%) étaient positifs pour S. aureus, dont 4 (10%) étaient SARM. Parmi les viandes congelées évaluées dans l'étude, le bœuf présentait la fréquence la plus élevée de contamination par S. aureus (46,7%), suivi du poulet (40,0%) et du poisson (30,0%). Le profil de résistance aux antibiotiques de S. aureus a montré qu'ils étaient les moins résistants à la ciprofloxacine (6%) mais présentaient une résistance élevée à l'érythromycine (94%), à l'amoxicilline/acide clavulanique (87,5%) et au triméthoprime-sulfaméthoxazole (81%). L'indice de résistance aux antibiotiques multiples de S. aureus a été calculé à 0,63.Conclusion: Les résultats de cette étude ont révélé que les aliments surgelés pourraient servir de vecteur de dissémination de bactéries résistantes aux antibiotiques (ARA) et de risques potentiels pour la santé des consommateurs. Mots clés: Staphylococcus aureus; bactéries résistantes aux antibiotiques; SARM; viande congelée; rinçag

Characterization of antibiotic resistance and species diversity of staphylococci isolated from apparently healthy farm animals

Background: Staphylococcus species are adaptable commensals usually involved in a diverse multiplicity of ailments in animals and humans. This study surveyed the occurrence, antibiotic-resistance profile and putative resistant genetic elements of staphylococci isolates from apparently healthy farm animalsMethodology: Nasal and rectal samples were collected from a total of 400 cows and pigs in Benin City between May and December 2017. Staphylococci were isolated following aerobic cultures of samples using standard microbiological methods. Susceptibility profiles of the isolates to eighteen selected antimicrobials were determined using the Kirby-Bauer disk diffusion test. Species of staphylococci were established and antibiotic resistance genes detected by the polymerase chain reaction using species-specific and antibiotic-resistant primers respectivelyResult: A total of 139 staphylococci isolates were phenotypically and genotypically identified from the food-producing animals; 87 (62.6%) from pigs and 52 (37.4%) from cows. The most frequent Staphylococcus species were Staphylococcus haemolyticus 38 (27.3%), Staphylococcus aureus 27 (19.4%) and Staphylococcus capitis 21 (15.1%). Antibiotic resistance profile showed 120 (86.3%) isolates to be resistant to penicillin G, 100 (71.9%) to nalidixic acid and 99 (71.2%) to minocycline. The prevalence of antibiotic resistance genes assessed were mecA 78 (56.1%), mphC 23 (16.6%), and ermA 20 (14.4%).Conclusion: Our finding indicates that food animals are potential reservoirs of antibiotic resistant staphylococci which pose a significant threat to food security and public health.Keywords: food animals; antibiotic-resistant; foodborne pathogen; staphylococci; resistance element