Manik Md Rasel Khan, Mishu Israt Dilruba, Mahmud Zimam, Muskan Muntaha Noor, Emon Sharmin Zaman
Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka 1000, Bangladesh.
Department of Microbiology, University of Dhaka, Dhaka 1000, Bangladesh.
J Infect Public Health. 2025 Jun;18(6):102766. doi: 10.1016/j.jiph.2025.102766. Epub 2025 Mar 21.
Urinary tract infections (UTIs) caused by Escherichia coli pose significant public health risks, particularly in developing countries like Bangladesh. This study aimed to elucidate resistance patterns among UTI isolates and comprehensively investigate the mutational spectrum and its impact on drug-microbe interactions.
We collected and identified E. coli isolates from hospitalized UTI patients at Dhaka Medical College Hospital and determined their resistance patterns using the disc diffusion method and broth microdilution. Quinolone resistance-determining regions (QRDRs) of the target genes (gyrA, gyrB, parC, and parE) associated with fluoroquinolone resistance were amplified by polymerase chain reaction (PCR) and analyzed through BTSeq™ sequencing for mutations, followed by molecular docking analysis using PyMOL and AutoDock for the protein-quinolone binding affinity (PQBA) study.
All isolates (100 %) displayed multidrug resistance, with chloramphenicol (16 % resistant) and colistin (28 % resistant) demonstrating superior efficacy compared to other antibiotics. The isolates resistant to colistin, as determined by disc diffusion testing, exhibited remarkably high minimum inhibitory concentrations (MICs), with one isolate registering an MIC exceeding 512 µg/mL. Alarming resistance rates were observed for five antibiotic classes, except for polymyxins (28 % resistant) and protein synthesis inhibitors (48 % resistant). Fifty-two percent (52 %) of the isolates exhibited resistance to all five tested quinolones. Sequence analysis revealed a novel L88Q mutation in ParC, affecting PQBA and binding conformation. Additionally, three ParC mutations (S80I, E84V, and E84G) and two ParE mutations (S458A and I529L) were identified, which had not been previously reported in Bangladesh. Among these, S80I appeared in all isolates. Double-mutations (S83L+D87N) in GyrA, L88Q and S80I in ParC, and I529L in ParE were identified as key drivers of fluoroquinolone resistance.
Our findings underscore the accumulation of significant mutations within QRDRs of UTI isolates, potentially compromising fluoroquinolone efficacy. The emergence of these novel mutations warrants further investigation to impede their dissemination and combat quinolone resistance.
由大肠杆菌引起的尿路感染（UTIs）对公众健康构成重大风险，在孟加拉国等发展中国家尤为如此。本研究旨在阐明尿路感染分离株的耐药模式，并全面调查突变谱及其对药物 - 微生物相互作用的影响。
我们从达卡医学院医院的住院尿路感染患者中收集并鉴定大肠杆菌分离株，并使用纸片扩散法和肉汤稀释法确定其耐药模式。通过聚合酶链反应（PCR）扩增与氟喹诺酮耐药相关的靶基因（gyrA、gyrB、parC和parE）的喹诺酮耐药决定区（QRDRs），并通过BTSeq™测序分析突变，随后使用PyMOL和AutoDock进行分子对接分析，以研究蛋白质 - 喹诺酮结合亲和力（PQBA）。
所有分离株（100%）均表现出多重耐药性，氯霉素（16%耐药）和黏菌素（28%耐药）与其他抗生素相比显示出更高的疗效。通过纸片扩散试验确定对黏菌素耐药的分离株表现出极高的最低抑菌浓度（MICs），其中一株分离株的MIC超过512μg/mL。除多粘菌素（28%耐药）和蛋白质合成抑制剂（48%耐药）外，观察到五种抗生素类别的耐药率令人担忧。52%的分离株对所有五种测试喹诺酮均耐药。序列分析揭示了ParC中一种新的L88Q突变，影响PQBA和结合构象。此外，还鉴定出三种ParC突变（S80I、E84V和E84G）和两种ParE突变（S458A和I529L），这些突变在孟加拉国此前尚未见报道。其中，S80I出现在所有分离株中。GyrA中的双突变（S83L + D87N）、ParC中的L88Q和S80I以及ParE中的I529L被确定为氟喹诺酮耐药的关键驱动因素。
我们的研究结果强调了尿路感染分离株QRDRs内显著突变的积累，这可能会损害氟喹诺酮的疗效。这些新突变的出现值得进一步研究，以阻止其传播并对抗喹诺酮耐药性。
