Serotype distribution and drug resistance of Shigella in children with diarrhea from 2008 to 2017 in Sui County, Henan Province / 中华传染病杂志

ABSTRACT

Objective:To explore the serotype distribution and drug resistance of Shigella in stool samples of children under five years old with diarrhea from 2008 to 2017 in Sui County, Henan Province. Methods:A total of 4 721 stool samples of children under five years old with diarrhea were collected from Doufuyuan Clinic of Sui County during 2008 to 2017, and Shigella strains were isolated through bacterial culture. The slide agglutination test was used for serotyping of Shigella strains. Two hundred of seventy-one Shigella strains were selected in proportion, and multiple gradient polymerase chain reaction was used to detect virulence genes and Kirby-Bauer agar method was used for drug sensitivity. Trend chi square test was used to analyze the annual trend of drug resistance. Results:The detection rate of Shigella strains in 4 721 fecal samples was 20.69% (977/4 721). A total of 977 Shigella strains were divided into 13 serotypes in two groups, including 77.79%(760/977) Shigella flexneri strains and 22.21%(217/977) Shigella sonnei strains.The top three serotypes detected alternately every year.The dominant gene pattern of Shigella flexneri was Shigella enterotoxin ( shET)-1+ , shET-2+ , invasion plasmid antigen H ( ipaH)+ , invasion-associated locus ( ial)+ , accounted for 84.04%(179/213) and that of Shigella sonnei was shET-1-, shET-2+ , ipaH+ , ial+ , accounted for 46.55%(27/58). The drug resistance rates of 271 Shigella strains to ampicillin, nalidixic acid and tetracycline were more than 90% and the strains were more sensitive to cefepime and ceftazidime.The drug resistance rates to cefotaxime, cefepime, ciprofloxacin, chloramphenicol and sulfamethoxazole/trimethoprim increased year by year, and all had statistically significant differences ( χ2=24.027, 7.232, 6.039, 4.764 and 6.809, respectively, all P< 0.05). There were 98.52%(267/271) strains resistant to more than three kinds of drugs. The resistance rates of Shigella flexneri to ciprofloxacin, norfloxacin, and chloramphenicol were higher than those of Shigella sonnei, and the resistance rates to gentamicin and sulfamethoxazole/trimethoprim were lower than those of Shigella sonnei. The differences were statistically significant ( χ2=31.866, 14.868, 83.036, 68.534 and 14.738, respectively, all P<0.01). Conclusions:The major serotypes of Shigella in children under five years old in Sui County are constantly changing from 2008 to 2017. The dominant gene patterns of different serotypes are different. Most isolated strains have multiple drug resistances, and different serotypes have different resistance profiles.