Antimicrobial susceptibility profiles and genotypic characterization of selected Enterobacteriaceae strains isolated from food handlers in Nairobi, Kenya

Abstract

Increased urbanization, industrialization as well as population growth in cities has led to an increase in consumption of food in public eating-places. Over 40% of Nairobi residents consume foods made outside their homes, and this raises possibilities of food contamination and dissemination of multi-drug resistant (MDRs) strains which confer resistance to multiple antimicrobial drugs such as β-lactams which are a unique class of antibiotics used for treatment of various infections. A cross-sectional study was conducted among 323 food-handlers in Nairobi and their socio-demographic profiles obtained using a structured questionnaire. Susceptibility profiling and phylogenic relatedness of isolates obtained from the participants of different socio-demographic characteristics were analyzed using Chi-square, culture and molecular strategies. Ethical clearance was sought from KEMRI/ IRB and a written informed consent obtained from all participants. There was near parity in the proportions of males (51%) and females (49%) recruited. Majority of the participants (75%) were between 18-30 years of age and working in middle class hotels. High resistances were recorded against Sulfamethoxazole/Trimethoprim (70%), Ampicillin (44.6%), Streptomycin (42%) and Tetracyclines (41%) while the Imipenem and Cefepime were effective against 99% of the isolates. A third 97(30%) of all isolates were multi-drug resistant (MDR), 11(3.4%) were ESBLs and 44.6% exhibited resistance to narrow spectrum β-lactams (NSBLs). The blaTEM gene was the most prevalent at 37%, blaSHV at 25%, blaCTX-M at 12% and blaOXA gene at 7%. The inhibitor resistant TEM phenotype, Complex mutant TEMs phenotypes and the plasmid-mediated ampicillin β-lactamases phenotypes accounted for <2%. In conclusion, the observed resistances pose a major therapeutic challenge since the isolates were obtained from apparently healthy food handlers who are capable of passing them to the general public. The study recommends proper and safe food handling practices among food handlers and the launch of surveillance studies on β-lactamase-producers in developing countries.