Pourakbari B, Mamishi S, Shokrollahi M R, Heydari H, Mahmoudi S, Banar M, Sadeghi R H, Movahedi Z
Pediatric Infectious Disease Research Center, Tehran University of Medical Sciences, Tehran, Iran.
Pediatric Infectious Disease Research Center, Tehran University of Medical Sciences, Tehran, Iran - Department of Infectious Diseases, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
Ann Ig. 2019 May-Jun;31(3):252-262. doi: 10.7416/ai.2019.2288.
Urinary tract infections (UTIs) are a highly prevalent infection among children and Escherichia coli is one of the most important pathogens causing pediatric UTIs. Production of extended spectrum b-lactamase (ESBL) enzymes is an important factor in the emergence of antibiotic resistance among these bacteria. This study aimed to determine the resistance patterns, the frequency of ESBL-encoding genes and the genetic diversity of E. coli strains isolated from children with UTIs who were admitted to children's referral hospital of Hazrat Masoumeh, Qom, Iran.
A total of 102 consecutive non-duplicative strains of E.coli that were isolated from children with UTIs were included into the study. Antibiotic susceptibility of the isolates was determined by disk diffusion method according to the CLSI guidelines. The ability of the isolates to produce ESBLs was phenotypically determined by both combined disk test and double disk synergy test. The ESBL encoding genes (bla CTX-M, bla SHV, and bla TEM) in phenotypically confirmed ESBL-positive isolates was detected by PCR method. The genetic relatedness of the isolates was designated by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR).
Eighty-three percent (n=85) of the children were female. Most of the infected boys (88%, n=15) were less than 1 year of age and most of the infected girls (48%, n=41) aged 1 to 6 years old. The highest sensitivity was observed to nitrofurantoin (8%, n=8), followed by amikacin (12%, n=12) and piperacillin-tazobactam (17%, n=17). In contrast, the highest resistance rate was seen to ampicillin (94%, n=96) and cefazolin (93%, n=95). Eighty-eight percent (90 out of 102) of the strains were multidrug-resistant (MDR). Fifty-eight percent (n=59) of the strains were ESBL-positive and results of the combined disk test was in concordance with PCR. The blaCTX-M was the most frequent ESBL encoding gene (88%, n=52), followed by blaTEM (54%, n=32), and blaSHV (15%, n=9). Based on the ERIC-PCR technique, isolates were clustered in 13 different types. There was no relationship between different ERIC types and origin of the isolates (i.e. hospitalized or outpatients), ESBL-producing ability, and antibiotic resistance patterns.
High prevalence of ESBL-positive isolates of E. coli (58%) was found in our study and all of them were MDR. In addition, there were statistically significant differences in the resistance rates of ESBL-producers, and non-producers to some antibiotics, which result in limiting their therapeutic options. Continuous surveillance of the emergence of ESBL-producing isolates and their antibiotic resistance profiles as well as using appropriate typing methods is needed for reducing their spread, selecting appropriate treatment regimens and finding hospital outbreaks.
尿路感染（UTIs）在儿童中是一种高度流行的感染，大肠杆菌是引起儿童尿路感染的最重要病原体之一。超广谱β-内酰胺酶（ESBL）的产生是这些细菌中抗生素耐药性出现的一个重要因素。本研究旨在确定从伊朗库姆哈兹拉特·马苏梅儿童医院收治的尿路感染患儿中分离出的大肠杆菌菌株的耐药模式、ESBL编码基因的频率以及遗传多样性。
本研究共纳入102株从尿路感染患儿中连续分离出的非重复大肠杆菌菌株。根据CLSI指南，采用纸片扩散法测定分离株的抗生素敏感性。通过联合纸片试验和双纸片协同试验从表型上确定分离株产生ESBL的能力。采用PCR方法检测表型确认的ESBL阳性分离株中的ESBL编码基因（bla CTX-M、bla SHV和bla TEM）。通过肠杆菌重复基因间共识PCR（ERIC-PCR）确定分离株的遗传相关性。
83%（n = 85）的儿童为女性。大多数感染的男孩（88%，n = 15）年龄小于1岁，大多数感染的女孩（48%，n = 41）年龄在1至6岁之间。观察到对呋喃妥因的敏感性最高（8%，n = 8），其次是阿米卡星（12%，n = 12）和哌拉西林-他唑巴坦（17%，n = 17）。相比之下，对氨苄西林（94%，n = 96）和头孢唑林（93%，n = 95）的耐药率最高。88%（102株中的90株）的菌株为多重耐药（MDR）。58%（n = 59）的菌株为ESBL阳性，联合纸片试验结果与PCR结果一致。blaCTX-M是最常见的ESBL编码基因（88%，n = 52），其次是blaTEM（54%，n = 32）和blaSHV（15%，n = 9）。基于ERIC-PCR技术，分离株聚为13种不同类型。不同的ERIC类型与分离株的来源（即住院患者或门诊患者）、产ESBL能力和抗生素耐药模式之间没有关系。
在我们的研究中发现大肠杆菌ESBL阳性分离株的高流行率（58%），并且所有这些分离株均为MDR。此外，ESBL产生菌和非产生菌对某些抗生素的耐药率存在统计学显著差异，这限制了它们的治疗选择。需要持续监测产ESBL分离株的出现及其抗生素耐药谱，并使用适当的分型方法来减少它们的传播、选择合适的治疗方案以及发现医院感染暴发。
