Tian Lei, Zhu Xuhui, Chen Zhongju, Liu Weiyong, Li Song, Yu Weiting, Zhang Wenqian, Xiang Xu, Sun Ziyong
Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
BMC Infect Dis. 2016 Jun 7;16:253. doi: 10.1186/s12879-016-1603-2.
Acute diarrhea is a leading cause of morbidity and mortality in children, particularly in those under the age of 5 years. Rotavirus is recognized as the leading cause of acute diarrhea in children, however, the contribution of bacterial pathogens as causative agents varies throughout the world. Here we report a hospital-based prospective study to analyze the characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age.
Stool samples were collected from 508 patients with acute diarrhea under 5 years of age who presented at our hospital. Nine pathogens were isolated and identified by culturing, serology or PCR, these included Salmonella spp., Shigella spp., Vibrio cholerae, diarrheagenic Escherichia coli (DEC), Aeromonas spp., Plesiomonas spp., Vibrio parahaemolyticus, Campylobacter spp. and Yersinia enterocolitica. Antimicrobial sensitivity tests of these pathogens were conducted. The most commonly detected pathogen, Salmonella spp., was further investigated by PCR and sequencing of antibiotic resistance-related genes.
Pathogens were identified in 20.1 % of the 508 samples. The most commonly detected pathogens were Salmonella spp. (8.5 %), followed by DEC (4.7 %), Campylobacter jejuni (3.0 %) and Aeromonas spp. (2.0 %). The resistance rates to ampicillin and tetracycline in Salmonella spp. were >60 %, but were <30 % to cephalosporins and quinolones. More than 50 % of DEC strains displayed resistance to ampicillin, cefotaxime and tetracycline, and 60 % of C. jejuni strains were resistant to ciprofloxacin but highly sensitive to the other antibiotics. Among 12 cephalosporin-resistant Salmonella isolates, TEM-1 and CTX-M-14 determinants were present in two (16.7 %) isolates. PCR screening for plasmid-mediated quinolone resistance genes revealed gyrA mutations in one of three highly quinolone resistant isolates.
Salmonella spp., DEC, Campylobacter spp. and Aeromonas spp. were the most commonly detected bacterial pathogens in children under the age of 5 years with acute diarrhea. Our findings indicate that ampicillin and tetracycline are not suitable as first line therapeutic drugs against Salmonella spp. Resistance to third generation cephalosporins and quinolones was also detected. TEM-1 and CTX-M-14 genetic determinants, and gyrA mutations, were the major mechanisms associated with high levels of cephalosporin and quinolone resistance, respectively, in Salmonella isolates.
急性腹泻是儿童发病和死亡的主要原因，尤其是5岁以下的儿童。轮状病毒被认为是儿童急性腹泻的主要原因，然而，细菌病原体作为致病因子的作用在世界各地有所不同。在此，我们报告一项基于医院的前瞻性研究，以分析5岁以下儿童急性腹泻相关细菌病原体的特征。
从我院就诊的508例5岁以下急性腹泻患者中采集粪便样本。通过培养、血清学或PCR分离并鉴定出9种病原体，包括沙门氏菌属、志贺氏菌属、霍乱弧菌、致泻性大肠杆菌（DEC）、气单胞菌属、类志贺邻单胞菌、副溶血性弧菌、弯曲菌属和小肠结肠炎耶尔森菌。对这些病原体进行了药敏试验。对最常检测到的病原体沙门氏菌属，通过PCR和抗生素耐药相关基因测序进行了进一步研究。
在508份样本中，20.1%鉴定出病原体。最常检测到的病原体是沙门氏菌属（8.5%），其次是DEC（4.7%）、空肠弯曲菌（3.0%）和气单胞菌属（2.0%）。沙门氏菌属对氨苄西林和四环素的耐药率>60%，但对头孢菌素和喹诺酮类药物的耐药率<30%。超过50%的DEC菌株对氨苄西林、头孢噻肟和四环素耐药，60%的空肠弯曲菌菌株对环丙沙星耐药，但对其他抗生素高度敏感。在12株耐头孢菌素的沙门氏菌分离株中，有2株（16.7%）存在TEM-1和CTX-M-14决定簇。对质粒介导的喹诺酮耐药基因进行PCR筛查发现，在3株高度耐喹诺酮的分离株中有1株存在gyrA突变。
沙门氏菌属、DEC、弯曲菌属和气单胞菌属是5岁以下急性腹泻儿童中最常检测到的细菌病原体。我们的研究结果表明，氨苄西林和四环素不适宜作为治疗沙门氏菌属的一线治疗药物。还检测到对第三代头孢菌素和喹诺酮类药物的耐药性。TEM-1和CTX-M-14基因决定簇以及gyrA突变分别是沙门氏菌分离株中高水平头孢菌素和喹诺酮耐药的主要机制。
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