Genotypic characterization of bacterial isolates causing urinary tract infections among adults at Kiambu Level 5 Hospital, Kenya: selected extended-spectrum β-lactamase genes and biofilm formation

Abstract

The menace of antimicrobial resistance affecting public health is rising globally. Many pathogenic bacteria use mechanisms such as mutations and biofilm formation, significantly reducing the efficacy of antimicrobial agents. In this cross-sectional study, we aimed to determine the prevalence of selected extended-spectrum β-lactamase (ESβL) genes and analyse the biofilm formation abilities of the isolated bacteria causing urinary tract infection among adult patients seeking Medicare at Kiambu Level 5 Hospital, Kenya. The double-disc synergy test was used for phenotypic identification of ESβL-producing isolates, while microtitre plate assays with some modifications were used for the biofilm formation test. Ten isolates were bioassayed for ESβL genes out of 57 bacterial isolates obtained from urine samples. This study found the bla TEM genes to be the most prevalent ESβL type [10/10 (100 %)], followed by blaOXA and blaSHV genes at 4/10 (40 %) and 3/10 (30 %), respectively. In addition, co-carriage of blaTEM and blaSHV was 50 % lower than that of blaTEM+bla OXA genes at 66.7 % among Escherichia coli isolates studied. Biofilm formation was positive in 36/57 (63.2 %) of the isolates tested, with most being Gram-negative [25/36 (69.4 %)]. Escherichia coli [15/36 (41.7 %)], Klebsiella species [7/36 (19.4 %)] and Staphylococcus aureus [7/36 (19.4 %)] were the dominant biofilm formers. However, there was no significant difference in biofilm formation among all tested isolates, with all isolates recording P-values >0.05. In light of these findings, biofilm formation potential coupled with antimicrobial resistance genes in urinary tract infection isolates may lead to difficult-to-treat infections.