Pathogenic spectrum and epidemiological characteristics of diarrhea patients in Tianjin during 2015-2017

Abstract

Objective To investigate the pathogenic spectrum and epidemiological characteristics of acute diarrhea patients in Tianjin. Methods A total of 1 536 stool samples of diarrhea patients were collected from hospitals between 2015 and 2017. Viral nucleic acids were detected by real-time polymerase chain reaction. Selective medium was used to culture bacteria. Drug susceptibility tests were performed by Kirby-Bauer disk diffusion method recommended by the Association for Standardization of Clinical Laboratories. χ2 test was used for statistical analysis. Results In the stool samples of 1 536 cases of diarrhea, one enteric bacterium was detected in 109 samples with the positive rate of 7.10%, one enterovirus was detected in 171 samples with the positive rate of 11.13%, mixed infection was detected in 20 samples with positive rate of 1.30%, including 8 samples with enteric bacterium and enterovirus and 12 samples with double enterovirus. The total detection rate of diarrhea cases was 19.53%. Norovirus, vibrio parahaemolyticus, rotavirus, Salmonella, stellate virus and sapovirus ranked the top six in the detection rate. The total detection rate curve of bacteria showed a single peak, mainly in August, while the total detection rate curve of the virus showed a double peak, which was from May to June and from November to December. The positive rate of bacteria in patients aged over 30 years old was 9.82% (75/764), while that in those aged less than 30 years old was 5.44% (42/772). The difference was statistically significant (χ2=10.451, P<0.01). The positive rate of viral pathogen in patients aged no less than 25 years old was 10.02% (91/908), while that in those aged less than 25 years old was 17.83% (112/628). The difference was statistically significant (χ2=19.755, P<0.01). Salmonella, Shigella and vibrio parahaemolyticus were resistant to ampicillin in varying degrees. Conclusions The positive rate curves of bacteria and virus are obviously different, showing a trend of "bacterial single peak and viral double peak" . Bacteria mainly infect people aged over 30 years old, while the virus mainly infects people under 25 years old. The main pathogens of diarrhea are norovirus, vibrio parahaemolyticus and rotavirus. Key words: Diarrhea; Population surveillance; Pathogen spectrum