POLYMYXIN B SUSCEPTIBILITY PROFILE IN GRAM-NEGATIVE BACTERIA MULTI-DRUG RESISTANT
Gram-negative bacteria; Polymyxin B; Bacterial resistance; Carbapenemases.
Bacterial resistance is a public health problem worldwide recognized. High prevalence of Gram-negative bacilli infections and its spread in the hospital environment, mainly by carbapenem resistant strains, is a recurrent concern due to its adaptive success and the ability to acquire more antimicrobial resistance genes. In this panorama, the emergence of resistance to carbapenems and the difficulty in developing new drugs, many authors postulate a return to the pre-antibiotic era. Although a more sustainable alternative is return abdicated antimicrobials such as polymyxins, polymyxin B and colistin, associated with combination therapy to achieve synergistic effects. In order to control and treat the patient adequately, local epidemiological data are fundamental. In knowledge of this, we carried out a study in the state of Rio Grande do Norte, whose main objective was to evaluate the profile of resistance to polymyxin B in carbapenems resistant Gram-negative bacteria from clinical samples isolated from reference health centers. One hundred and seventy-four bacteria from infected or colonized patients were collected. The isolates were submitted to manual biochemical tests for identification of the species, confirmatory phenotypic analysis (modified Hodge-test and metallo-β-lactamases screening) also analysis of susceptibility to polymyxin B through microdilution in broth were performed. Of these strains, 105 (60.3%) were confirmed as producers of metallo-β-lactamases, more than half among to the genus Acinetobacter spp., other species such as Pseudomonas aeruginosa and Klebsiella pneumoniae also expressed the same phenotype. Regarding susceptibility to polymyxin B, 53 (30.5%) were resistant to polymyxin B, with minimal inhibitory concentrations (MIC) ranging from ≥4μg / mL to ≤64μg / mL. CIM50 and CIM90 values were calculated for each species. It is hoped that these results can be extended and used as a reference at the state level, preventing the dispersion of this resistance and also serving as a more national data to build a more reliable profile regarding the epidemiology of this resistance that despite rare already points out its emergency.