Pullanhi Unnimaya, Khan Sadia, Vinod Vivek, Mohan Karthika, Kumar Anil
Department of Microbiology, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India.
Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India.
Ann Afr Med. 2019 Jul-Sep;18(3):138-142. doi: 10.4103/aam.aam_49_18.
Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) strains is one of the most important community-acquired infections in the world. The presence of virulence factors is closely related with the pathogenesis of UTI.
The present study was conducted on 150 isolates of UPEC obtained from symptomatic and asymptomatic cases of UTIs with significant counts (≥10 CFU/ml) during 1 year. UPEC isolates were studied for hemolysis on 5% sheep blood agar, mannose-sensitive hemagglutination (MSHA), mannose-resistant hemagglutination (MRHA), and biofilm formation by recommended methods. Patients with UTI due to UPEC showing virulence factors were evaluated for the treatment received and the outcome of treatment. These were compared with the outcomes of patients whose culture samples grew UPEC without demonstrable virulence factors.
The study showed hemolysin production in 40% of the isolates. Forty percent of the isolates showed the presence of P fimbriae (MRHA) and 60% showed Type 1 fimbriae (MSHA). Biofilm formation capacity of all UPEC isolates was classified into three categories, strong biofilm producers (4%), moderate biofilm producers (88%), and nonbiofilm producers (8%). Patients harboring all three virulence factors showed 76% recovery compared to patients harboring strains with no demonstrable virulence factors, who showed 100% recovery.
The present study has shown the production of various virulent factors and developing drug resistance in UPEC. Treatment outcomes of patients harboring strains with no virulence factors seem to be better than the ones which contain multiple virulence factors. UPEC occurs because of multiple virulence factors. Biofilm formation and MRHA are more likely to be seen in catheterized patients. The drug resistance among UPEC is on rise; therefore, the selection of appropriate antibiotics (after antibiotic susceptibility testing) is must for proper treatment of patients and to avoid emergence of drug resistance. Significant number of the UPEC isolates was sensitive to nitrofurantoin, and half of the isolates were sensitive to cotrimoxazole, so treatment is by giving these drugs orally.
由尿路致病性大肠杆菌（UPEC）菌株引起的尿路感染（UTI）是全球最重要的社区获得性感染之一。毒力因子的存在与UTI的发病机制密切相关。
本研究对150株UPEC分离株进行了研究，这些分离株取自1年内有症状和无症状UTI病例且计数显著（≥10 CFU/ml）的样本。采用推荐方法对UPEC分离株进行5%绵羊血琼脂上的溶血、甘露糖敏感血凝（MSHA）、甘露糖抗性血凝（MRHA）及生物膜形成研究。对因UPEC导致UTI且显示毒力因子的患者的治疗情况及治疗结果进行评估。将这些结果与培养样本中生长出无明显毒力因子的UPEC的患者的结果进行比较。
研究显示40%的分离株产生溶血素。40%的分离株显示存在P菌毛（MRHA），60%显示1型菌毛（MSHA）。所有UPEC分离株的生物膜形成能力分为三类：强生物膜产生菌（4%）、中度生物膜产生菌（88%）和非生物膜产生菌（8%）。携带所有三种毒力因子的患者恢复率为76%，而携带无明显毒力因子菌株的患者恢复率为100%。
本研究显示了UPEC中各种毒力因子的产生及耐药性的发展。携带无毒力因子菌株的患者的治疗结果似乎优于携带多种毒力因子的患者。UPEC因多种毒力因子而发生。生物膜形成和MRHA在导尿患者中更易出现。UPEC中的耐药性正在上升；因此，为了对患者进行恰当治疗并避免耐药性的出现，（在进行抗生素敏感性试验后）选择合适的抗生素是必需的。大量UPEC分离株对呋喃妥因敏感，一半的分离株对复方新诺明敏感，所以通过口服这些药物进行治疗。
