Azam Sadiq, Rehman Noor, Alhegaili Alaa S, Khan Ibrar, Ahmad Aakash, Khalil Atif Ali Khan, Ali Sajid
Centre of Biotechnology and Microbiology, University of Peshawar, Peshawar, 25120, Pakistan.
Department of Microbiology, University of Swabi, Anbar, 23561, Swabi, Pakistan.
Curr Microbiol. 2025 Aug 22;82(10):470. doi: 10.1007/s00284-025-04460-2.
Salmonella typhi is a facultative anaerobic, rod-shaped, Gram-negative bacterium that causes typhoid fever, a potentially fatal systemic infection. This study aimed to characterize antibiotic susceptibility patterns, mutations at the molecular level, and efflux pump genes in clinical isolates. In this study, blood samples (n = 2950) were collected from suspected typhoid-infected patients, and 380 (12.88%) bacterial isolates were found, comprising 144 (37.89%) Gram-positive and 236 (62.10%) Gram-negative bacteria. S. typhi was identified in 95 isolates (25%), corresponding to an overall prevalence of 3.22%. Biochemical identification was performed by Analytical Profile Index (API) 20-E strips, and molecular identification was done by partial 16S rRNA gene using PCR. The S. typhi isolates were categorized into multidrug-resistant (MDR), 13 (13.68%), and extensively drug-resistant (XDR), 82 (86.31%), and their resistance patterns were recorded. Ampicillin (98.94%) and chloramphenicol (93.68%) showed the highest antibiotic resistance profiles, while azithromycin and meropenem exhibited no resistance. Numerous mutations were found in acrA, acrB, and tolC genes after sequencing; TolC (MDR) showed the highest score (16 points), and AcrB (MDR) displayed the lowest score (9 points). I-Mutant 2.0 was used to assess mutations and calculate the reliability index (RI), whereas trRosetta and Discovery Studio were used to predict and refine 3D protein models. Consensus sequences of the selected genes were analyzed to construct phylogenetic trees illustrating evolutionary relationships with other Salmonella enterica serovars. The study emphasizes the concerning multidrug resistance of S. typhi isolates as well as notable mutations (genetic changes) that may affect efflux pump activity and contribute to resistance.
伤寒沙门氏菌是一种兼性厌氧、杆状、革兰氏阴性细菌，可引起伤寒热，这是一种潜在致命的全身性感染。本研究旨在表征临床分离株中的抗生素敏感性模式、分子水平的突变以及外排泵基因。在本研究中，从疑似伤寒感染患者中采集了血液样本（n = 2950），发现了380株（12.88%）细菌分离株，其中包括144株（37.89%）革兰氏阳性菌和236株（62.10%）革兰氏阴性菌。在95株分离株（25%）中鉴定出伤寒沙门氏菌，总体患病率为3.22%。通过分析谱指数（API）20 - E条带进行生化鉴定，通过PCR使用部分16S rRNA基因进行分子鉴定。将伤寒沙门氏菌分离株分为多重耐药（MDR），13株（13.68%），以及广泛耐药（XDR），82株（86.31%），并记录它们的耐药模式。氨苄西林（98.94%）和氯霉素（93.68%）显示出最高的抗生素耐药率，而阿奇霉素和美罗培南未显示耐药性。测序后在acrA、acrB和tolC基因中发现了许多突变；TolC（MDR）得分最高（16分），AcrB（MDR）得分最低（9分）。使用I - Mutant 2.0评估突变并计算可靠性指数（RI），而trRosetta和Discovery Studio用于预测和优化3D蛋白质模型。分析所选基因的共有序列以构建系统发育树，说明与其他肠炎沙门氏菌血清型的进化关系。该研究强调了伤寒沙门氏菌分离株令人担忧的多重耐药性以及可能影响外排泵活性并导致耐药性的显著突变（基因变化）。
