Guangzhou Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, 510623, People's Republic of China.
Department of Gastroenterology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, 510623, People's Republic of China.
Infect Dis Poverty. 2018 May 7;7(1):53. doi: 10.1186/s40249-018-0427-2.
Bacterial diarrhea is one of the most common causes for medical consultations, mortality and morbidity in the world. Diarrheagenic Escherichia coli (DEC) and non-typhoidal Salmonella (NTS) are major intestinal pathogens in developing countries, and the indiscriminate use of antibiotics has greatly contributed to resistant strains. Hence, the aim of the present study is to identify the antimicrobial resistance patterns and the molecular characteristics of DEC and NTS in southwest, China.
1121 diarrheal patients and 319 non-diarrheal subjects across all age groups were recruited from four sentinel hospitals from June 2014 to July 2015 in Kunming City, Yunnan Province. Each stool specimen was collected to detect DEC and NTS with standard microbiological and molecular methods. Antimicrobial resistance testing was performed with the Kirby-Bauer disk diffusion method, and the standards for antimicrobial susceptibility testing complied with the Clinical and Laboratory Standards Institute (CLSI). Molecular characterization of strains was carried out using pulsed-field gel electrophoresis (PFGE). A structured questionnaire was used to record basic epidemiological data (e.g. sex, age, residence, season, etc.). Data were analyzed using Chi-square or Fisher's exact test.
DEC was detected in 127 (11.33%) diarrhea cases and 9 (2.82%) non-diarrheal cases (χ = 20.69, P < 0.001, OR = 4.36, 95% CI: 2.19-8.65), and the prevalence of NTS isolated from diarrhea cases was higher than that of non-diarrheal cases across all age groups (n = 42, 3.75%, n = 1, 0.31%, χ = 10.10, P = 0.002, OR = 12.38, 95% CI: 1.70-90.29). The rates of resistance to ten antibiotics of DEC and NTS showed significant differences (χ = 386.77, P < 0.001; χ = 191.16, P < 0.001). The rates of resistance to Amoxicillin and Clavulafiate (AMC), Cephalothin (CEP), Gentamicin (GEN) and Sulfamethoxazole-Trimethoprim (SXT) of DEC isolated from diarrhea cases were higher than those of NTS isolated from diarrhea patients (37.01% vs 14.29%, χ = 7.57, P = 0.006; 29.92% vs 11.90%, χ = 5.40, P = 0.02; 37.01% vs 11.90%, χ = 5.80, P = 0.016; 62.20% vs 26.19%, χ = 16.44, P < 0.001; respectively). Ciprofloxacin (CIP) was the most sensitive antibiotic for DEC and NTS strains isolated from diarrhea cases. Resistance rates of DEC isolates from cases and controls to more than three kinds antimicrobials (multidrug resistance, MDR) showed no significant differences (81.10% vs 88.89%, P = 0.33). Pulsotype patterns of DEC strains were highly diverse; however, the pulsotype pattern of NTS strains was closely related to the serotype. The pattern of S. enteritidis was highly similar, but the S. enterica Typhimurium strain was discrete.
Antibiotic resistance of Enterobacteriaceae is of great concern. The societal effects of antibiotic use justify strict monitoring to combat increases in antimicrobial resistance. Molecular epidemiology and systematic epidemiological investigation can provide accurate evidence for tracking the infection source.
细菌性腹泻是世界范围内导致医疗咨询、死亡和发病的最常见原因之一。产肠毒性大肠杆菌（DEC）和非伤寒沙门氏菌（NTS）是发展中国家的主要肠道病原体，抗生素的滥用极大地促成了耐药菌株的出现。因此，本研究旨在确定中国西南部 DEC 和 NTS 的抗菌药物耐药模式和分子特征。
2014 年 6 月至 2015 年 7 月，从云南省昆明市的四个哨点医院招募了 1121 名腹泻患者和 319 名非腹泻患者，涵盖所有年龄段。每个粪便标本均采用标准微生物学和分子方法检测 DEC 和 NTS。采用 Kirby-Bauer 纸片扩散法进行抗菌药物敏感性试验，抗菌药物敏感性试验标准符合临床和实验室标准协会（CLSI）的要求。采用脉冲场凝胶电泳（PFGE）对菌株进行分子特征分析。使用结构化问卷记录基本的流行病学数据（如性别、年龄、居住地、季节等）。采用卡方或 Fisher 确切检验分析数据。
在腹泻病例中检测到 DEC 127 例（11.33%），在非腹泻病例中检测到 9 例（2.82%）（χ 2 = 20.69，P < 0.001，OR = 4.36，95%CI：2.19-8.65），从腹泻病例中分离的 NTS 的检出率高于所有年龄段的非腹泻病例（n = 42，3.75%，n = 1，0.31%，χ 2 = 10.10，P = 0.002，OR = 12.38，95%CI：1.70-90.29）。DEC 和 NTS 的十种抗生素耐药率差异有统计学意义（χ 2 = 386.77，P < 0.001；χ 2 = 191.16，P < 0.001）。从腹泻病例中分离的 DEC 对阿莫西林克拉维酸（AMC）、头孢噻吩（CEP）、庆大霉素（GEN）和磺胺甲噁唑-甲氧苄啶（SXT）的耐药率高于从腹泻患者中分离的 NTS（37.01% vs 14.29%，χ 2 = 7.57，P = 0.006；29.92% vs 11.90%，χ 2 = 5.40，P = 0.02；37.01% vs 11.90%，χ 2 = 5.80，P = 0.016；62.20% vs 26.19%，χ 2 = 16.44，P < 0.001）。环丙沙星（CIP）是 DEC 和 NTS 菌株对腹泻病例最敏感的抗生素。从病例和对照中分离的 DEC 对三种以上抗生素（多重耐药，MDR）的耐药率无显著差异（81.10% vs 88.89%，P = 0.33）。DEC 菌株的脉冲型模式高度多样化，而 NTS 菌株的脉冲型模式与血清型密切相关。肠炎沙门氏菌的模式高度相似，但肠炎沙门氏菌 Typhimurium 株则不同。
肠杆菌科的抗生素耐药性令人关注。抗生素使用的社会影响需要严格监测，以遏制抗菌药物耐药性的增加。分子流行病学和系统的流行病学调查可以为追踪感染源提供准确的证据。
