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Background & objectives: Shigella spp. are gram negative bacteria that can cause shigellosis in human. It is important in young children as well as elderly and immunocompromised people. Threatening complications can occur in severe cases with multidrug resistance species. It has been observed that Shigella spp. have become resistant to antibiotics like other bacteria. Investigation of resistance to azithromycin, tetracycline and pattern of resistance are the objectives of this study.

Methods: Fifty isolates of Shigella spp. which have been collected from three hospitals in Tehran were studied. Isolates identified and confirmed as Shigella spp. by biochemical, serological and molecular methods (ipaH, wbgz, rfc genes). Antimicrobial susceptibility test was performed for ampicillin, azithromycin, ciprofloxacin, doxycycline, levofloxacin, minocycline, nalidixic acid, norfloxacin, streptomycin, trimethoprim-sulfamethoxazole and tetracycline by disc agar diffusion method. Minimal inhibition concentrations were performed for azithromycin and tetracycline.

Results: From a total of 50 Shigella spp. isolates, 16% of them were Shigella flexneri and 84% Shigella sonnei. The majority of isolates were multidrug resistant. The most resistance was seen to doxycycline, streptomycin, trimethoprim-sulfamethoxazole and tetracycline. Resistance to azithromycin was 6%  and all of the isolates were susceptible to norfloxacin and levofloxacin. Nine patterns of resistance were revealed to these isolates.

Conclusion: High resistance to tetracycline was observed and resistance to azithromycin as an alternative treatment choice was also considerable.

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Background & objectives: Shigella species are one of the most common causes of dysentery and sometimes death, especially in children and those with immunodeficiency. The variety of causative agents (Shigella species) and the development of drug-resistant strains make it difficult to select an appropriate antibiotic for the treatment of shigellosis. One of the most important factors involved in the resistance of Shigella isolates is the presence of extended spectrum beta lactamases (ESBLs) genes. The aim of this study was to determine the frequency of blaPER, blaGES and blaVEB genes in Shigella sonnei isolated from patients with dysentery using multiplex-PCR method and to determine the antibiotic susceptibility patterns of these isolates.
Methods: A total of 60 isolates of Shigella sonnei were collected from different hospitals and medical ‎diagnostic laboratories in Kerman province. Specimens from different age groups were cultivated in special media ‎and confirmed by biochemical tests. The presence of blaPER, blaGES and blaVEB genes were ‎investigated using specific primers and multiplex-PCR method. Antibiotic susceptibility test was ‎performed by disc diffusion method based on CLSI standards. ‎
Results: Multiplex-PCR results showed three samples had blaPER gene, but none of them had blaVEB or blaGES ‎genes. Also, the results of antibiotic susceptibility test showed the highest resistance for amoxicillin- clavulanic ‎acid (53.3%) antibiotic and the highest sensitivity for tetracycline (85%) antibiotic.‎
Conclusions: The results of the experiments indicated the presence of blaPER gene in Shigella sonnei isolates. In ‎addition, the results showed high resistance of isolates to amoxicillin clavulanic acid and ceftriaxone ‎antibiotics. Therefore, careful medical care and proper and timely use of appropriate antibiotics are essential to ‎prevent the spread of resistant isolates. ‎