Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Indian J Med Microbiol. 2020 Jul-Dec;38(3 & 4):421-429. doi: 10.4103/ijmm.IJMM_20_365.
Horizontal gene transfer of virulence genes (VGs) from different Escherichia coli pathotypes results in the evolution of hybrid strains. Hybrid genotypes of enteroaggregative E. coli and uropathogenic E. coli (EAEC/UPEC) have been reported in sporadic infections and outbreaks of extraintestinal origin. Yet, their association with routine infections is still underrated.
In this study, we analysed 163 isolates of E. coli from cases of urinary tract infection seeking hybrid (EAEC/UPEC) strains. Using multiplex polymerase chain reaction, we investigated VGs (adhesive and toxin genes) of UPEC along with EAEC marker genes (aap and agg R), ast A (toxin genes) and serine protease autotransporters of Enterobacteriaceae, pet (plasmid-encoded toxin) and pic (mucinase gene). Those UPEC strains which had characteristic defining genes of EAEC (agg R/aap or their combination) were considered UPEC/EAEC hybrids.
Molecular predictors of EAEC (aap and aggR) were detected in 20.2% (33/163) of the strains. The pap C was also detected in 36% of the EAEC/UPEC hybrid strains. Phylogenetic analysis revealed that hybrid strains belonged to Group D (60.6%). Nearly 73.8% of UPEC and 75.7% of UPEC/EAEC hybrid strains were multidrug-resistant. Among UPEC isolates, 72.3% and in hybrid UPEC/EAEC, 78.7% isolates were able to produce biofilm.
Our results indicated a closer relationship among EAEC and UPEC, which suggested that some EAEC strains can be potential uropathogens. Ours is a first study documenting the existence of EAEC pathotypes VGs in UPEC strains of nosocomial origin; further studies are required to understand the diarrhoeagenic potential of these hybrids.
来自不同大肠杆菌病原型的毒力基因（VGs）的水平基因转移导致了混合菌株的进化。肠聚集性大肠杆菌和尿路致病性大肠杆菌（EAEC/UPEC）的混合基因型已在散发性感染和肠道外来源的暴发中报道。然而，它们与常规感染的关联仍被低估。
在这项研究中，我们分析了来自尿路感染病例的 163 株大肠杆菌分离株，以寻找混合（EAEC/UPEC）菌株。使用多重聚合酶链反应，我们调查了 UPEC 的 VGs（粘附和毒素基因）以及 EAEC 标记基因（aap 和 aggR）、astA（毒素基因）和肠杆菌科的丝氨酸蛋白酶自转运体、pet（质粒编码毒素）和 pic（粘蛋白酶基因）。那些具有 EAEC 特征定义基因（aggR/aap 或其组合）的 UPEC 菌株被认为是 UPEC/EAEC 混合菌株。
分子预测因子 EAEC（aap 和 aggR）在 20.2%（33/163）的菌株中被检测到。papC 也在 36%的 EAEC/UPEC 混合菌株中被检测到。系统发育分析显示，混合菌株属于 D 组（60.6%）。近 73.8%的 UPEC 和 75.7%的 UPEC/EAEC 混合菌株是多药耐药的。在 UPEC 分离株中，72.3%和混合 UPEC/EAEC 分离株中，78.7%的分离株能够产生生物膜。
我们的结果表明 EAEC 和 UPEC 之间存在更密切的关系，这表明一些 EAEC 菌株可能是潜在的尿路病原体。我们的研究首次记录了肠道外来源的 UPEC 菌株中存在 EAEC 病原体 VGs；需要进一步的研究来了解这些混合菌株的腹泻潜力。
