Transfer of Antibiotic Resistance Marker Genes between Lactic Acid Bacteria in Model Rumen and Plant Environments

Abstract

Three wild-type dairy isolates of lactic acid bacteria (LAB) and one Lactococcus lactis control strain were analyzed for their ability to transfer antibiotic resistance determinants (plasmid or transposon located) to two LAB recipients using both in vitro methods and in vivo models. In vitro transfer experiments were carried out with the donors and recipients using the filter mating method. In vivo mating examined transfer in two natural environments, a rumen model and an alfalfa sprout model. All transconjugants were confirmed by Etest, PCR, pulsed-field gel electrophoresis, and Southern blotting. The in vitro filter mating method demonstrated high transfer frequencies between all LAB pairs, ranging from 1.8 ؋ 10 ؊5 to 2.2 ؋ 10 ؊2 transconjugants per recipient. Transconjugants were detected in the rumen model for all mating pairs tested; however, the frequencies of transfer were low and inconsistent over 48 h (ranging from 1.0 ؋ 10 ؊9 to 8.0 ؋ 10 ؊6 transconjugants per recipient). The plant model provided an environment that appeared to promote comparatively higher transfer frequencies between all LAB pairs tested over the 9-day period (transfer frequencies ranged from 4.7 ؋ 10 ؊4 to 3.9 ؋ 10 ؊1 transconjugants per recipient). In our test models, dairy cultures of LAB can act as a source of mobile genetic elements encoding antibiotic resistance that can spread to other LAB. This observation could have food safety and public health implications.

The effect of antimicrobials on verocytotoxin bacteriophage transduction under bovine rumen fluid and broth conditions

“…After 1 h of incubation, all test tube samples were co-inoculated with 3 mL of C600φ3538(Dvtx 2 ::cat) (donor strain) and 3 mL of C600::kanamycin R (recipient strain) at a concentration of approximately 4 log 10 cfu/mL. The samples were flashed with CO 2 and re-fitted with the rubber stoppers as before (Toomey et al, 2009). All test tubes were incubated at 38°C in a water bath without shaking.…”

Decellularized human amniotic membrane: more is needed for an efficient dressing for protection of burns against antibiotic-resistant bacteria isolated from burn patients

“…On the other hand, the prevalence of antibiotic-resistant bacteria is increasing due to the overuse of antibiotics, especially in developing countries. Development of multidrug-resistant (MDR) strains has become a major concern in the health-care community [12][13][14]. The aim of this study was to investigate whether HAM (both fresh and decellularized) can protect burns from antibiotic-resistant infections, as an ideal burn wound dressing.…”

Antibiotic Susceptibility of Probiotic Bacteria

“…In vitro mating, using a traditional filter mating technique, showed that all four LAB mating pairs transferred their resistance determinants at high frequencies. By employing two in vivo models, an alfalfa sprout plant and an animal rumen model Toomey et al., (2009) demonstrated the transfer of resistance determinants between all four LAB mating pairs in these models. Previously, in vivo transfer between LAB has only been shown in the gastrointestinal tracts of gnotobiotic rats (Jacobsen et al, 2007) and mice (McConnell et al, 1991;Morelli et al, 1988).…”

“…Toomey et al, (2009) reported on the ability of wild-type antibiotic resistance determinants [erm(B) and tet(M)], present in LAB strains isolated from food sources, to be transferred to recipient strains. In vitro mating, using a traditional filter mating technique, showed that all four LAB mating pairs transferred their resistance determinants at high frequencies.…”