Mudanças no fenótipo de resistência a antibióticos em Salmonella enterica após exposição às condições gastrointestinais simuladas em carne de frango

Abstract

The increasing emerging antibiotic resistance in Salmonella enterica has been considered public health problem, however few it is known about the effects of exposure to gastrointestinal conditions on the resistance phenotype of epidemic strains of this pathogen. This study evaluated the effects of exposure of exposure of fifteen outbreak-linked Salmonella enterica strains in chicken meat to simulated human gastrointestinal conditions on susceptibility to 11 antibiotics of seven distinct classes were evaluated. The minimum inhibitory concentration of each antibiotic was determined by microdilution broth before and after the exposure of each strain to a 9-steps continuous system simulating the mouth (1st step), esophagus-stomach 2nd to 7 th steps, duodenum (8th step) and ileum (9th step) in irradiated chicken meat (20g; 5 log CFU / g). Data were interpreted according Clinical and Laboratory Standards Institute breakpoints values (μg / mL). Before in vitro digestion, all strains of S. enterica showed resistance to at least two antibiotics and S. Derby presented the highest resistance frequency. None of the strains tested showed resistance to cefepime (FEP) and polymyxin (PB) before or after simulated digestion. Twelve strains with reduced susceptibility to ciprofloxacin (CIP) changed to CIP resistant after in vitro digestion. S. Newport ceftriaxone (CTX)-intermediary changed to CTX resistant. Ampicillin (AMP)-susceptible S. Heidelberg changed to AMP-resistant, while S. Typhimurium, S. Agona, S. Newport, S. Albany and S. Corvallis sulfamethoxazole/ trimethoprim (SXT)-susceptible changed to SXT-resistant. S. Heidelberg, S. Newport, S. Albany and S. Corvallis showed the highest frequency of change in antibiotic susceptibility with new-resistant phenotype to AMP and CIP, CTX and SXT, CIP and SXT and CIP and SXT, respectively. Conditions imposed by a simulated gastrointestinal environment changes the susceptibility of S. enterica to clinically relevant antibiotics and should be considered in the selection therapies for human salmonellosis.