Variants of the CTX-M gene in strains isolated from urine cultures

Variants of the CTX-M gene in strains isolated from urine cultures

Valeria V. Torres-Occa 1 , Eliana X. Urbano-Cáceres 1 , Diana P. López-Velandia 1

1 Universidad de Boyacá, Boyacá, Tunja, Colombia

*Correspondence: Diana P. López-Velandia. Email: dplopez@uniboyaca.edu.co

Abstract

Objective: This study aimed to detect the presence of the CTX-M gene using polymerase chain reaction (PCR) and to analyze its different variants in bacterial strains isolated from urine cultures. Urinary tract infections (UTIs) are a common reason for medical consultation, particularly among women of reproductive age. Enterobacteriaceae is the most frequently isolated bacterial group and often exhibits resistance mechanisms such as extended-spectrum β-lactamase (ESBL) production, with SHV, OXA, TEM, and CTX-M being the most prominent. Method: An observational, descriptive, cross-sectional study was conducted using 60 strains from the collection of the Molecular Epidemiology Laboratory at the University of Boyacá. Among them, 29 strains exhibited ESBL-type resistance and carried the CTX-M gene, as identified by PCR. Sanger sequencing was subsequently performed to determine the specific gene variants. Results: Of the 60 strains isolated from urine cultures, 48.3% carried the CTX-M resistance gene. One strain was found to harbor the CTX-M-15 variant, which is widely associated with UTIs. A literature review identified other CTX-M variants potentially linked to UTIs. Their nucleotide sequences were determined and used to construct a dendrogram illustrating their genetic and phylogenetic relationships. Conclusions: CTX-M-producing β-lactamase pathogens are widely distributed in the community and are typically resistant to most antibacterial agents. Effective strategies must be developed and implemented to prevent and control the spread of this resistance mechanism.

Keywords: CTX-M gene. Bacteria. Antimicrobial resistance. Urinary tract infection. Variants.

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