Mutation analysis of dihydrofolate reductase (dfr) and dihydropteroate synthase (sul) genes in trimethoprim-sulfamethoxazole-resistant Escherichia coli from urinary tract infections.
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引用次数: 0
Abstract
Background and objectives: Escherichia coli is the leading cause of urinary tract infections (UTIs) and has shown increasing resistance to trimethoprim-sulfamethoxazole (TMP-SMX). Resistance to TMP-SMX is commonly associated with the acquisition of resistance genes such as dfr and sul, often mediated by horizontal gene transfer. This study aimed to characterize the presence of dfr (dfrA1, dfrA5, dfrA7/17) and sul (sul1 and sul2) genes and to describe sequence variations in selected E. coli isolates.
Materials and methods: Urine culture samples were obtained from 678 patients suspected of having UTIs, and 21 samples yielded positive culture results. This study further analyzed 11 E. coli isolates, consisting of eight TMP-SMX-resistant isolates, two susceptible isolates, and one E. coli ATCC 25922 strain as a control. The clinical isolates were provided by the Clinical Microbiology Laboratory, Faculty of Medicine, Universitas Indonesia. PCR amplification and agarose gel electrophoresis were used to identify dfr and sul genes, followed by Sanger sequencing of selected amplicons. Sequence data were analyzed with BioEdit software and aligned against reference sequences from NCBI.
Results: The distribution of resistance genes varies among resistant isolates. Some isolates carry the dfrA5 gene, while dfrA1 was detected in one isolate. The sul2 gene was present in a number of resistant isolates, while sul1 was identified but showed no differences from the reference sequence. Further sequence analysis revealed amino acid changes in the dfrA1, dfrA5, and sul2 genes, although these changes were not consistently found in all isolates.
Conclusion: This study characterizes the distribution of dfr and sul genes and their sequence variations in a limited number of E. coli isolates. The results suggest that TMP-SMX-resistant isolates may contain diverse genetic determinants associated with resistance. Nevertheless, the limited isolate number restricts the broader interpretation of these findings. Larger-scale studies, supported by functional analyses, are required to determine the contribution of these genes and their sequence variations to antibiotic resistance.
期刊介绍：
The Iranian Journal of Microbiology (IJM) is an international, multi-disciplinary, peer-reviewed journal that provides rapid publication of the most advanced scientific research in the areas of basic and applied research on bacteria and other micro-organisms, including bacteria, viruses, yeasts, fungi, microalgae, and protozoa concerning the development of tools for diagnosis and disease control, epidemiology, antimicrobial agents, clinical microbiology, immunology, Genetics, Genomics and Molecular Biology. Contributions may be in the form of original research papers, review articles, short communications, case reports, technical reports, and letters to the Editor. Research findings must be novel and the original data must be available for review by the Editors, if necessary. Studies that are preliminary, of weak originality or merely descriptive as well as negative results are not appropriate for the journal. Papers considered for publication must be unpublished work (except in an abstract form) that is not under consideration for publication anywhere else, and all co-authors should have agreed to the submission. Manuscripts should be written in English.
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