Shigellosis and Changes of Antimicrobial Susceptibility During Six Years

Abstract

Background: Shigellosis is a diarrheal disease caused by Shigella spp. The majority of cases and deaths occur among children less than 5 years old. In severe cases, antibiotic therapy is recommended to lessen the risk of serious complications and death. Prevalence of different Shigella species and their antibiotic resistance patterns are changing over the time. Objectives: The current study aimed at assessing the changes in the prevalence of Shigella species and their antibiotic susceptibility among 0-to 14-year-old children referred to Children's Medical Center, Tehran, Iran, from 2009 to 2014. Methods: The results of stool cultures were retrospectively analyzed to determine the prevalence of different Shigella species, their antibiotic susceptibility patterns and their changes in the largest university affiliated pediatrics center in Tehran. Results: Among 40 700 stool cultures, 507 cases were positive for Shigella spp. Most cases occurred among children under 5 years old. Shigellosis was more prevalent among males. The most common species were Shigella sonnei and Shigella flexneri. In general, they were most sensitive to cefotaxime and most resistant to cotrimoxazole. Resistance to cefotaxime and nalidixic acid increased annually. Resistance to ampicillin had a descending trend. Resistance to cotrimoxazole remained almost constant. Conclusions: The most common species of Shigella changed from Shigella flexneri to Shigella sonnei over the years. In comparison with the previous studies, resistance to nalidixic acid increased and resistance to ampicillin decreased. The prevalence and antibiotic resistance patterns of Shigella species, at different times and regions are changing. To make appropriate decisions on treatment, it is necessary to monitor the changes.

Determination of Antibiotic Resistance Pattern and frequency of CTX-M, TEM, and SHV Β-Lactamase Encoding Genes among Shigella Isolates from Inpatients in Tehran, Iran

“…S. sonnei and S. flexneri are the most commonly isolated species in industrialized (23) and developing countries (24), respectively. In our study, S. sonnei was the most common cause of shigellosis, which is consistent with findings of other studies in Iran (25)(26)(27). Reasons behind the dominance of S. sonnei in industrialized countries remain unclear (28), but an increasing incidence of shigellosis caused by S. sonnei generally correlates with improving economic prosperity (29).…”

“…However, more than 34% of Shigella isolates in our study were resistant and intermediately resistant to nalidixic acid. In a study by Ghavam et al in Iran, a similar frequency for resistance to nalidixic acid was observed (26), but in some countries higher resistance rates have been reported (7,31). Multi-drug resistance to the antimicrobial agents used for the treatment of shigellosis has been reported in many parts of the world (31,33,34).…”