Emergence of resistant salmonella spp.; new challenges, new trends

Salmonella enterica is a common cause of human food borne gastroenteritis and bacteremia worldwide. Salmonellosis is caused by different serotypes of salmonella; humans and animals are generally infected with these bacteria by the consumption of contaminated food products (1-3). Non-typhi salmonella gastroenteritis in contrast to the invasive salmonellosis that requires prompt antibiotic therapy, is usually self-limited (4). According to the WHO license for the treatment of salmonellosis in last decades, increasing usage of antimicrobial agents in clinics and slaughterhouses is becoming a major problem (5). Chloramphenicol, sulfamethoxazole-trimethoprim, and ampicillin were the earliest antibiotics used the treatment of salmonellosis. However, following the development of resistance to the aforementioned drugs, quinolones and cephalosporines are currently in use (6). The usage of quinolones and cephalosporines in the veterinary world as the therapeutic agents or growth factors led to the emergence of highly resistant veterinary Salmonella strains which might transfer into human via the food chain process. This transmission will cause failure in clinical treatment of related diseases (7, 8). Frequency of antimicrobial resistance found among isolates from human is directly linked to