Antimicrobial susceptibility of probiotic lactobacilli isolated from chicken feces

Abstract

This work aimed to study the primary properties and antimicrobial susceptibility patterns of probiotic lactobacilli isolated from native chicken feces.Sixty five isolates of Lactobacillus spp. were screened for acid and bile tolerants trains and also subjected to susceptibility test against 11 antibiotics using the disk diffusion method. All selected Lactobacillus isolates had acid and bile tolerant properties and none had acquired resistance to antibiotics. Antibiotics were distinguished and identified to species level using pulsed-field gel electrophoresis (PFGE) and nucleotide sequences analysisof the16SrRNA gene, respectively. The results of acid and bile tolerance tests showed that 11 isolates exhibited positive signs.Six out of 11 isolates showed a strong sensitivity to penicillin, tetracycline and chloramphenicol and a moderate sensitivity to bacitracin,erythromycin and nitrofurantoin.Four isolates resisted tetracycline and 1 isolate had bacitracin resistance. All 11 isolates were resistant to vancomycin, nalidixic acid and aminoglycoside antibiotics (gentamicin,neomycinandstreptomycin). Based on acid and bile tolerance and without acquired resistance to antibiotics, 6 probiotic lactobacilli were selected. They were differentiated into 5 different PFGE patterns.All isolates of 5PFGE patterns were identifiedas L. salivariuswith99%to100%nucleotidesequence identities compared to GenBank (accessionnumber CP000233.1)