Diarrhea pathogens in rotavirus-negative infants in Hangzhou

Abstract

Objective To investigate the distribution of diarrhea pathogens in infants without rotavirus-detection in Hangzhou. Methods 605 stool samples of children with rotavirus-negative diarrhea were collected from Hangzhou First People's Hospital of Zhejiang University, Children's Hospital of Zhejiang University and Hangzhou Children's Hospital from March 2017 to June 2018. The routine test results were analyzed retrospectively and Bristol score was used for the characteristics of stool samples. DNA and/or RNA were extracted from fecal samples with DNA and RNA extraction kit. The extracted DNA and RNA-reversed cDNA were used as templates. 7 common pathogens DNA and/or RNA were amplified by polymerase chain reaction (PCR). The amplified products were detected by agarose gel electrophoresis. The positive rates of pathogens were analyzed by chi-square test. Results Among 605 children, 375 were male(28±11) months and 230 were female (29±10) months. Bristol score of stool samples was mainly in type 6 (496, 82%), followed by type 7 (85, 14%) and type 5 (24, 4%). Among 605 results 97 cases were occult blood positive (positive rate 16%) and 170 cases were white blood cell positive (positive rate 28%).452 of 605 stool samples were positive for pathogen target genes. The positive rate was 74.7%. 319 cases detected single pathogen gene fragments. 127 cases detected two pathogen genes and 6 cases detected three pathogen gene fragments. The positive rate of Clostridium difficile toxin B (48.9%, 296/605)was the highest than the others, followed by Salmonella (20.0%, 121/605) and Norovirus (10.9%, 66/605). The positive rate of Clostridium difficile toxin A was 1.0% (6/605). The positive rates of pathogens in male and female children were 86.7% (325/375) and 86.5% (199/230) respectively, with (χ2=0.002, P=0.959). Conclusions Salmonella and Norovirus were the main pathogens in children with diarrhea who were negative for rotavirus detection in Hangzhou. The high positive rate of Clostridium difficile toxin B may be related to the colonization of Clostridium difficile in the gastrointestinal tract of infants rather than the pathogen of diarrhea because of the low positive rate of Clostridium difficile toxin A. There was no gender difference in the detection rate of diarrhea pathogens. Key words: Diarrhea; Salmonella; Norovirus; Bacterial toxins; Polymerase chain reaction; Epidemiologic studies