belonging to ST131 rarely transfers to fecal .

BACKGROUND

Extended spectrum beta-lactamase (ESBL)-producing () causing urinary tract infections often belong to sequence type 131 (ST131), serotype O25, carrying .

AIM

The main aim of this study was to examine the conjugational frequencies of with plasmids carrying to isolates from the fecal flora of healthy humans to determine whether ST131 is more likely to uptake or donate ESBL resistance compared to other clones.

METHODS

Donors and recipients were all clinical isolates and did not harbor plasmids with identical incompatibility groups (Inc-groups) based on in silico analyses of Inc-groups and restriction/modification systems (R/M-systems). The in vitro conjugation experiments were performed as filter conjugation with verification of transconjugants by random amplified polymorphic DNA (RAPD) PCR and PCR.

RESULTS

The frequencies of conjugation with -carrying plasmids were found to be very rare with detectable conjugation frequencies in the range of 4x10-7x10 transconjugants/recipient. Recipients of O25/ST131 type yielded significantly lower conjugation frequencies compared to recipients of other O-types (=0.004). The applied ST131/O25 donors did not yield detectable levels of transconjugants regardless of the applied recipient. Presence of sub-MIC levels of ampicillin increased plasmid transfer frequencies x100 fold (=0.07).

CONCLUSION

The results indicate that is rarely transferred by conjugation to isolates of the intestinal flora, even when the gene is plasmid-borne.