However recipient exhibited lesser MIC values (Table 5). Further, Selleck MK-8776 results showed that transfer of qnrB gene from donor to recipient through conjugation was inhibited with increasing concentration of EDTA and complete inhibition (100%) was observed at 10 mM EDTA disodium ( Fig. 3, statistical analysis is presented

in Table 6). Similarly, when various drugs were evaluated on the conjugation, only Potentox could inhibit 100% transfer of qnrB gene from donor to recipient. Whereas other drugs could inhibit only 0.4–3.5% ( Fig. 4 and Table 7). Results of conjugation study of cefepime, amikacin, and amoxicillin plus clavulanic acid are not shown in figure. Resistance to quinolones has been a problem ever since Tanespimycin chemical structure nalidixic acid was introduced into clinical medicine > 40 years ago.7 Several studies have indicated that the quinolone resistance in Enterobacteriaceae ranged from 17% to 56%. 26, 27 and 28 Quinolone resistant plasmid produce Qnr protein which protects the quinolone targets from inhibition. 29 The susceptibility test results has shown that Potentox is the most active agent as compared to other drugs used in the present investigation. It is probably

because of chelation of divalent ions required for the stability of the outer membrane of clinical isolates thus enhanced susceptibility of Potentox as compared to other drugs; EDTA also diminished the barrier of drug penetration.30 and 31 Earlier, it has been demonstrated that sub-inhibitory concentrations of EDTA (0.1–10.0 mM) reduce the MIC of some penicillins and other agents on strains of E. coli, P. aeruginosa and Proteus mirabilis by enhancing the penetration of drugs into the bacterial cells. 32 The results of the conjugation experiments demonstrated that qnrB positive E. coli clinical isolates (donor) transferred the qnrB gene in transconjugants, PDK4 this transferability

was in agreement with the findings of other studies. 13 and 33 Susceptibility profiles of transconjugants was identical to the donor suggesting the complete transfer of resistant quinolone gene. But when EDTA was used in conjugation system, EDTA alone at 10 mM inhibited the conjugal transfer of qnrB gene. This inhibition by EDTA is probably due to the chelation of divalent metal ions (Ca2+ and Mg2+) required for the activity of relaxase enzyme. The most significant observation of this study was the inhibition of conjugal transfer of qnrB gene from donor to recipient with Potentox at the concentration of half of MIC of drug. Probably, EDTA present in the solvent of Potentox prevents the transfer of qnrB gene to recipient suggesting that 10 mM EDTA when being used as a solvent of Potentox have an immediate effect in the prevention of spreading of antibiotic resistance as well as enhancing the susceptibility of Potentox. However, there was no relationship between inhibition of qnrB gene transfer when conjugation system was provided with other comparator drugs.