PCR-Based Identification of Integrons Types and Extended-Spectrum Β-Lactamase Genes in Salmonella Species Collected from Pediatric Diarrheal Samples

Abstract

Objective: Salmonella is a significant pathogen between food-borne diseases. Salmonella spp. strains that produce extended-spectrum β-Lactamases (ESBL) have become a medical problem for both antimicrobial therapy and infection control programs. The aim of this project was detection of ESBL genes and class I, II and III Integrons in the Salmonella isolates.

Methods: 405 non-duplicative stool samples were obtained. Antibacterial susceptibility was defined by the disk diffusion and also double disk synergy test (DDST) was used for confirming of ESBL phenotype. The multiplex-PCRs were directed for recognition of ESBLs (TEM, CTX-M and SHV) and int (I, II, III) genes.

Results: Out of 405 samples, 54 (13.4%) Salmonella were obtained. The highest resistance rate was related to the NA (51.8%), followed by SXT (50%), CTX (46.3%), and AMP (33.3%). DDST was conducted for all isolates and 7 (12.9%) Salmonella spp were ESBL positive. Molecular analysis showed that 5 (9.3 %) of isolates were carried blaTEM-1 which belonged to the S. infantis and S. typhimurium. Three (5.5%) non-typeable isolates and 2 S. typhimurium were positive for the CTX-M gene. The prevalence of different classes of integrons showed that 23 (42.5%) isolates carried the integrase (int) gene.

Conclusion:This research demonstrates the predominant existence in the Salmonella of the TEM and CTX-M genes. So, class I integron were more prevalent than class II and III in Salmonella isolates. They are capable of transferring to bacteria of this genus and also the other genus of intestinal ones.