Assessment of antibiotic susceptibility in Lactobacillus isolates from chickens

Abstract

BackgroundThe aim of this study was to determine the susceptibility of 88 Lactobacillus isolates derived from chickens to antibiotic substances and to detect drug-resistance genes.ResultsThe minimal inhibitory concentration of 13 antimicrobial substances was determined by the broth microdilution method, and resistance genes were detected by PCR. We recorded a high prevalence of resistance to tiamulin (90% resistant isolates), tetracyclines (74%) and lincomycin (70%), and a moderately high frequency of resistance to enrofloxacin (48%), macrolides (42%), aminoglycosides (12.5–31%), ampicillin (26%) and chloramphenicol (23%). Multi-drug resistance was observed in 79.5% of isolates. The presence of resistance genes was generally correlated with phenotypic resistance, but some molecular determinants were also recorded in susceptible isolates. Among tetracycline resistance genes, the most frequently identified was tetW (45% isolates), followed by tetM (26%) and tetL (24%). The ermB, ermC and lnuA genes, associated with resistance to macrolides and lincosamides, were observed in 39, 12 and 39% of isolates, respectively. Among genes determining resistance to aminoglycoside antibiotics, we identified ant(6)-Ia (10% of isolates), aac(6′)-Ie-aph(2′)-Ia (8%), aph(2″)-Ic (6%) and aadE (4.5%). The cat gene was present in 32 isolates, including 8 of 20 found to be resistant to chloramphenicol. Two genes encoding efflux pumps were identified—the acrA gene was present in all isolates tested, and 10 of 79 lactobacilli determined to be phenotypically resistant to tiamulin contained the lsaE gene. We were unable to explain the resistance mechanism of Lactobacillus isolates to ampicillin, but showed that it did not involve the production of β-lactamases.ConclusionsOur findings indicate that intestinal lactobacilli should be considered a reservoir of resistance genes and that antibiotics must be used prudently in poultry production. The data derived from this study can be used as a basis for reviewing current microbiological breakpoints for categorization of susceptible and resistant strains within the genus Lactobacillus.

Genus-Wide Assessment of Antibiotic Resistance in Lactobacillus spp

“…We also confirmed low-level resistance to rifampin, as previously reported for Lactobacillus species isolated from the human GIT (36), traditional dairy products (37), and in probiotic strains in marketed foods and drugs (38). Generally, we found Lactobacillus species to be susceptible to low concentrations of ␤-lactams, including penicillin and ampicillin (16), even though atypical insensitivity to higher concentrations of these cell wall inhibitors has been reported for some L. crispatus and L. johnsonii strains isolated from healthy chickens (39). Higher levels of resistance to ampicillin compared to penicillin were detected for the type strains analyzed, in line with some previous studies (40)(41)(42).…”

“…Chloramphenicol (cat genes) and tetracycline resistance determinants [tet(M), tet(S), tet(W), tet(O), and tet(Q)] are the most commonly acquired resistance genes found in lactobacilli (15,19,39,60,61). In particular, the most widespread resistance genes are tet(M) and tet(S) in foodborne and probiotic bacteria (12,14,62) due to the frequent association of tet(M) with conjugative transposons, such as Tn916 (63), which was corroborated by this study.…”

Phenotypic and Molecular Analysis of Antibiotic Resistance in Lactobacilli of Poultry Origin from Lahore, Pakistan

“…Lower level of ampicillin or penicillin resistance has been detected in lactobacilli of different origins i.e fermented foods (Nawaz et al, 2011), human gut (Klare et al, 2007), chicken meat (Shazali et al, 2014) and poultry gut (Shazali et al, 2014;Dec et al, 2017). Our results are in agreement with a previous study (Dec et al, 2017), which declared moderately higher level of ampicillin resistance in lactobacilli. Resistance to ampicillin is mainly encoded by beta-lactamases which breaks the beta-lactam ring of ampicillin (Tenover, 2006).…”

Bactopia: a flexible pipeline for complete analysis of bacterial genomes

“…The linking thread between these species is they are each commonly isolated from agricultural animals. The high proportion of L. crispatus samples isolated from chickens that were tetracycline resistant has been previously observed (105, 106) ( Figure 3 ).…”