Molecular Typing and Occurrence of Extended-Spectrum Beta-Lactamases (ESBLs) Genes among Klebsiella oxytoca Isolated from Selected Hospitals in Khorramabad, Iran

Resistance of Klebsiella spp to various antibiotic families, such as beta-lactams, has increased due to the acquisition of plasmids carrying genes for Extended-Spectrum Beta-Lactamases (ESBLs). Today, ESBLs have become a major problem in healthcare settings.

This study aimed to determine the molecular fingerprinting and frequency of bla_TEM, bla_SHV,bla_CTX-M, bla_GES, bla_PER, and bla_VEB genes among Klebsiella oxytoca from clinical samples collected in selected hospitals in Khorramabad, Iran.

The present study was a cross-sectional study of Klebsiella oxytoca isolated from clinical specimens collected at selected hospitals in Khorramabad in 2019. After phenotypic identification of the isolates studied, antibiotic susceptibility patterns and beta-lactamase screening were performed using the disk diffusion method; genes encoding resistance were detected by PCR, and molecular fingerprinting was performed by PFGE.

In this study, 32 K. oxytoca were isolated. The highest resistance rates were observed with ampicillin (93.8%) and cefotaxime (65.6%), and the lowest resistance rates were observed with colistin (0%), imipenem (15.6%), and amikacin (18.8%). 56.6% of isolates were ESBL- producing. Nineteen (59.4%), 2 (6.3%), and 16 (50%) isolates carried the bla_TEM, bla_SHV, and bla_CTX-M genes, respectively. In addition, bla_GES, bla_PER, and blaVEB genes were not found in any of the tested isolates. Molecular typing results by the PFGE method showed that the isolates were very heterogeneous, and the 32 tested isolates were clustered in 18 pulse types.

In the present study, K. oxytoca isolates exhibited concerning resistance to certain antibiotics, particularly cephalosporins. The high prevalence of ESBLs and bla_TEM and bla_CTX-M genes highlights the importance of continuous monitoring of these factors. On the other hand, the absence of bla_GES, bla_PER, and bla_VEB genes and the high genetic heterogeneity of bacterial strains in PFGE indicate high strain diversity and the possibility of multiple sources of contamination.

Overall, the results of this study showed that the isolation and examination of K. oxytoca isolates in terms of diversity and molecular susceptibility profiling are important.