Coexistence of aminoglycoside resistance genes in CTX-M-producing isolates of in Bushehr province, Iran.

BACKGROUND AND OBJECTIVES

Increasing the rate of extended-spectrum β-lactamase (ESBL)-producing has given rise to a major healthcare issue in clinical settings over the past few years. Treatment of these strains is hardly effective since the plasmid encoding ESBL may also carry other resistance genes including aminoglycosides. The current study aimed to evaluate the prevalence of ESBL-producing and investigate the coexistence of Cefoxitamase-Munich ( ) with aminoglycoside-modifying enzyme (AME) genes, as well as , in CTX-M-producing isolated from patients in Bushehr province, Iran.

MATERIALS AND METHODS

A total of 212 isolates were collected and confirmed using polymerase chain reaction (PCR) of the malate dehydrogenase gene. Isolates were screened for production of ESBL. Phenotypic confirmatory test was performed using combined disk test. The genes encoding CTX-M groups and AME genes, and were investigated by PCR.

RESULTS

The ESBL phenotype was detected in 56 (26.4%) isolates. Moreover, 83.9% of ESBL-producing isolates carried the genes for CTX-M type β-lactamases, which were distributed into the two genetic groups of CTX-M-1 (97.8%)- and CTX-M-2 (2.1%)-related enzymes. Notably, among isolates containing the gene, 68.08% of isolates harbored AME genes. In addition, the coexistence of with and was observed in 46.8% of CTX-M-producing isolates.

CONCLUSION

This study provides evidence of a high prevalence of AME genes in CTX-M-producing isolates; therefore, in the initial empirical treatment of infections caused by ESBL-KP in regions with such antibiotic resistance patterns, aminoglycoside combination therapy should be undertaken carefully.