Antimicrobial Susceptibility of Lactic Acid Bacteria Strains of Potential Use as Feed Additives - The Basic Safety and Usefulness Criterion

Abstract

The spread of resistance to antibiotics is a major health concern worldwide due to the increasing rate of isolation of multidrug resistant pathogens hampering the treatment of infections. The food chain has been recognized as one of the key routes of antibiotic resistant bacteria transmission between animals and humans. Considering that lactic acid bacteria (LAB) could act as a reservoir of transferable antibiotic resistance genes, LAB strains intended to be used as feed additives should be monitored for their safety. Sixty-five LAB strains which might be potentially used as probiotic feed additives or silage inoculants, were assessed for susceptibility to eight clinically relevant antimicrobials by a minimum inhibitory concentration determination. Among antimicrobial resistant strains, a prevalence of selected genes associated with the acquired resistance was investigated. Nineteen LAB strains displayed phenotypic resistance to one antibiotic, and 15 strains were resistant to more than one of the tested antibiotics. The resistance to aminoglycosides and tetracyclines were the most prevalent and were found in 37 and 26% of the studied strains, respectively. Phenotypic resistance to other antimicrobials was found in single strains. Determinants related to resistance phenotypes were detected in 15 strains as follows, the aph(3″)-IIIa gene in 9 strains, the lnu(A) gene in three strains, the str(A)-str(B), erm(B), msr(C), and tet(M) genes in two strains and the tet(K) gene in one strain. The nucleotide sequences of the detected genes revealed homology to the sequences of the transmissible resistance genes found in lactic acid bacteria as well as pathogenic bacteria. Our study highlights that LAB may be a reservoir of antimicrobial resistance determinants, thus, the first and key step in considering the usefulness of LAB strains as feed additives should be an assessment of their antibiotic resistance. This safety criterion should always precede more complex studies, such as an assessment of adaptability of a strain or its beneficial effect on a host. These results would help in the selection of the best LAB strains for use as feed additives. Importantly, presented data can be useful for revising the current microbiological cut-off values within the genus Lactobacillus and Pediococcus.

Safety Assessment of Lactiplantibacillus plantarum TWK10 Based on Whole-Genome Sequencing, Phenotypic, and Oral Toxicity Analysis

“…The MIC for kanamycin (128 mg/L) was 2-fold higher than the cut-off value specified by the EFSA (Table 2). This result was consistent with those of previous studies [55][56][57]. Many Lactobacillus species are resistant to aminoglycoside antibiotics, such as streptomycin, kanamycin, and gentamicin [58].…”

“…Many Lactobacillus species are resistant to aminoglycoside antibiotics, such as streptomycin, kanamycin, and gentamicin [58]. In addition, the enzyme aminoglycoside phosphotransferase type III, encoded by the aph(3 )-III gene, which is associated with resistance to kanamycin, has previously been detected in kanamycin-resistant L. plantarum strains [55,57]. Moreover, Feng et al [59] demonstrated that non-synonymous mutations in genes regulating major facilitator family protein, ABC transporter substrate-binding protein, and histidine kinase play an important role in increasing kanamycin resistance in L. plantarum.…”

A Review of Current Bacterial Resistance to Antibiotics in Food Animals

“…These findings suggest that the food chain of animal products has been one of the important sources of ARB and ARGs transmission between animals and humans, posing a serious global public health threat. The abundant presence of ARB and ARGs transferring from animals to humans may have profound influences on future treatment, highlighting the importance of implementing hygiene measures to decrease the spread risk, thus, it urgently needs to be integrated, multi-sectoral, and global strategies ( Overdevest et al, 2011 ; Stefanska et al, 2021 ).…”

Microbial Ecology of Sheep Milk, Artisanal Feta, and Kefalograviera Cheeses. Part II: Technological, Safety, and Probiotic Attributes of Lactic Acid Bacteria Isolates

“…The latter is very useful as it may indicate presence of antibiotic resistance genes. Indeed, LAB are considered as a pool of transferable antibiotic resistance genes, the spread of which has been recognized as a major problem for public health [11,12]. Production of antimicrobial compounds is a useful trait that may assist in controlling of foodborne pathogens occurrence and proliferation.…”