Prevalence and virulence factors of Shigella spp. isolated from patients with diarrhoea in Rosario, Argentina

Abstract

The aim of this study was to determine the prevalence and virulence factors of Shigella species isolated from patients with diarrhoea. Shigella species were isolated from 1022 stool samples collected from different hospitals of Rosario, Argentina. The isolates were characterized by using phenotypic tests, serotyping and determination of the virulence genes by PCR. A total of 100 (9,7%) strains of Shigella were isolated. Shigella flexneri was the most frequent serogroup (74%) followed by Shigella sonnei (26%). Shigella flexneri was the predominant species isolated among the 6-14 years age-group. These clinical strains of Shigella spp. were then tested to detect ipaH, virA, ial, sen and set genes employing specific primers. The virA gene was positive in all strains; the ipaH gene was detected in 98% strains and the ial gene in 83%. The 71,6% of Shigella flexneri and 42,3% of Shigella sonnei were positive for sen gene. The 41,9% of Shigella flexneri were positive for set gene. Further, 32,4% of Shigella flexneri were positive for both set and sen genes. This study provides initial data on the prevalence and distribution in a wide variety of Shigella strains of the set, sen, ipaH, virA and ial genes.