Infectious Diseases, Prevention and Control

Aim: The study aims to assess the possibility of clodronic acid to inhibit the standard reagent of P. aeruginosa Metallo-βLactamase (MβL)/Sigma, USA/ and to prevent the acquisition of resistance by Gram-negative bacteria that were previously susceptible to carbapenems. Method: The final load of sensitive to Meropenem (MIC 2 μg/ml) reference strains of P. aeruginosa ATCC 27853, A. baumannii ATCC BAA-747, K. pneumoniae ATCC 70603 was 5×104 CFU in 200 μl, exposure 24 hours. Checkerboard array was used to determine the enzyme activity against Meropenem (MIC 2-512 μg/ml) as well as to evaluate the possibility of clodronic acid sub-bactericidal doses to inhibit the standard reagent of P. aeruginosa MβL and to prevent the acquisition of resistance to carbapenems by previously sensitive strains. Suppression of the MβL by clodronic acid and as a result, the lack of growth of the test strains were confirmed in microcells, as well as on the EL×800 reader (Bio-Tek Instruments Inc., USA). Result: A dose-dependent effect of acquiring resistance to Meropenem in Gram-negative bacteria (increasing MIC) in the presence of various amounts of the standard reagent of the enzyme ÐœβL at an exposure of 24 hours was revealed. At the same time, P. aeruginosa MβL reagent leads to the emergence of resistance in other types of Gram-negative microorganisms previously sensitive to carbapenems. Sub-bactericidal doses of clodronic acid do not affect the growth of intact sensitive test strains, but at the same time its ½ MIC and ¼ MIC completely inhibit the activity of the standard P. aeruginosa MβL reagent and prevent the acquisition of resistance of previously sensitive to carbapenems Gram-negative bacteria. Conclusion: Using this method will simplify the search for perspective inhibitors of MβL.