Studying the Cross-Protection between Some Environmental Stressors and Antibiotics Resistance on Salmonellaspp.

Abstract

Salmonella enterica isolates were divided into three groups; high antibiotic resistant (S1 and S2) group, low antibiotic resistant (S3 and S4) group and control according to results of antibiotics susceptibility test. , acid resistance of Salmonellaenterica isolates were investigated by exposure of bacteria to 3% lactic acid and calculating the D-value of bacterial population. Results of this experiment showed that D-values of the two strains (S3 and S4) (0.82 and 0.83 respectively) were significantly (p ≥ 0.05) higher than D-value of control (0.77). While, there was no significant difference between strains (p ≥ 0.05) (S1 and S2) (0.79 and 0.76 respectively) when compared to control. The relationship between antibiotic susceptibility and gene expression of acid and heat resistant sigma factors rpoS and rpoH genes have been investigated respectively. Results demonstrated no significant difference (p ≥ 0.05) in levels of transcription between rpoS and rpoH genes after exposure to 3% lactic acid for one minute between antibiotic resistant and antibiotic susceptible groups. Results of rpoD gene expression showed significant increase between both antibiotic resistant and antibiotic susceptible (p ≥ 0.04) and (p ≥ 0.001) respectively.