Objective: To investigate class I integron of Shigella flexneri, its prevalence in children, and its relation to bacterial resistance to antimicrobial agents.
Methods: Totally 51 strains of Shigella flexneri were isolated from fecal samples of children suffering from bacterial diarrhea seen between June 2004 and November 2004 at Children's Hospital of Fudan University. Polymerase chain reaction (PCR) was employed to amplify various integron markers, including intI1, gene cassette region and 3' conserved region of class I intrgron; susceptibility of Shigella flexneri strains to 7 antimicrobial agents was determined by K-B (Kriby-Bauer) method.
Results: Forty-six strains of Shigella flexneri had intI gene with a positive rate of 90.2% (46/51); 24 strains of Shigella flexneri were positive for qacEDelta1-sul1, the positive rate was 47.1% (24/51); proportion of the isolates positive for all the three regions of class I integron was 43.1% (22/51); 46 strains of intI positive Shigella flexneri were all positive for ant (3'')-I. Among 46 strains of intI positive isolates, proportions of the isolates positive and negative for qacEDelta1-sul1 were 47.8% (22/46) and 52.2% (24/46), respectively. In the class I integron positive Shigella flexneri, the resistance rates of ampicillin (chi(2) = 10.13, P < 0.01) and chloramphenicol (chi(2) = 19.97, P < 0.01) were significantly higher than those in the class I integron-negative group.
Conclusions: Class I integron was detected in 90.2% of Shigella flexneri in children; carriage of class I integron is related to antimicrobial resistance of Shigella flexneri.