Antibiotic Susceptibility of Bifidobacterium thermophilum and Bifidobacterium pseudolongum Isolates from Animal Sources

Abstract

The widespread use of antimicrobial substances has led to resistant populations of microorganisms in several ecosystems. In animal husbandry, the application of antibiotics has contributed to resistance development in pathogenic and commensal bacteria. These strains or their resistance genes can be spread along several ecological routes, including the food chain. Antibiotic resistance is important in terms of the safety of industrial strains, such as probiotics for food and feed. Bifidobacterium thermophilum and Bifidobacterium pseudolongum are known to comprise the major part of the bifidobacterial microbiota in the gut and feces of cattle and pigs. In this study, the antimicrobial susceptibility in bifidobacterial isolates of these species was investigated. Isolates from the beef and pork production chain were identified and typed to strain level, and the antimicrobial susceptibility level was tested to a set of antibiotics. Isolates with low susceptibility levels were screened by PCR for already described resistance genes. Strains atypically resistant to clindamycin, erythromycin, and tetracycline were determined. The resistance genes tet(O), tet(W), and erm(X) were detected in the bifidobacterial species that were examined.

Antibiotic Susceptibility of Bifidobacterial Strains Distributed in the Japanese Market

“…Acquired resistance to erythromycin and clindamycin has been reported in strains of lactobacilli and bifidobacteria, and the resistance determinants have been identified. 10,32,33) Resistance gene erm(X) has been identified in some strains of erythromycin-resistant B. thermophilum and B. animalis subsp. lactis which exists as part of transposon Tn5432 that has been described in several opportunistic pathogens.…”

“…Several molecular determinants for antibiotic resistance have been described for bifidobacteria, the bbmr gene of Bifidobacterium breve for resistance to macrolides, 9) the erm(X) gene for resistance to erythromycin and clindamycin, 10,11) and tet genes for resistance to tetracyclines. 12) Many studies have been carried out on the antimicrobial susceptibility of bifidobacterial strains isolated from humans, animals and probiotic products in European countries.…”

Pig Manure Contamination Marker Selection Based on the Influence of Biological Treatment on the Dominant Fecal Microbial Groups

“…These bacterial groups were selected either because they are dominant in manure microbial communities (Eubacterium-Clostridiacea, Bacteroides-Prevotella, BSL) or due to their known host specificity. Thus, phylogenetic groups of Bacteroides-Prevotella have been associated with pig feces (14,22,43,44) and the genus Bifidobacterium consists of species of animal or human origin (17,40).…”

“…Molecular markers have been developed to target the 16S rRNA gene sequences of dominant Eubacteria (2,14,43,48) or methanogenic Archaebacteria (54) of the pig intestinal tract, whereas Khatib et al (29) targeted the STII toxin gene from enterotoxigenic E. coli. Among the dominant groups of pig fecal Eubacteria, which include Bacteroides-Prevotella, Eubacterium-Clostridiacea, Lactobacillus-Streptococcus (34,45,51,58), and to a lesser extent Bifidobacterium (40), the Bacteroides-Prevotella group has been particularly well studied (14,22,44). This marker of pig feces was described by Okabe et al (44), but their work was based on feces sampled from only two farms and the number of clones analyzed was low.…”

Antimicrobial Susceptibility of Bacillus Strains Isolated from Primary Starters for African Traditional Bread Production and Characterization of the Bacitracin Operon and Bacitracin Biosynthesis

“…The aliquots (1 ml) of the stock solutions were stored at Ϫ20°C until use (not exceeding a 4-week storage period). The MICs of antibiotics (mg/liter) for all the bacteria were determined by a modification of the broth microdilution method (13,35) with different antibiotic concentration ranges depending on the particular antibiotic. In summary, an appropriate amount of the antibiotic stock solution (2.0 g/liter) was added to BHI broth (pH 7.4) followed by a log 2 serial dilution in the same medium until the desired concentrations were obtained.…”