New STs in multidrug-resistant Acinetobacter baumannii harbouring -lactamases encoding genes isolated from Brazilian soils

AimsWe investigated the resistance profile, presence of -lactamases encoding genes and the clonal relationships in Acinetobacter baumannii isolated from Brazilian soils. Methods and ResultsSoil isolates of A. baumannii were subjected to antimicrobial susceptibility testing by disk diffusion and minimum inhibitory concentration methods. Different -lactamases encoding genes were screened by PCR and the molecular typing of these isolates was performed through the multilocus sequence typing. Non-susceptibility to different antibiotics was found, since environmental isolates were classified as multidrug-resistant. The bla(SHV) gene was the most prevalent, followed by bla(GES.) All sequence types (STs) found (ST1584, ST1607, ST1608, ST1609, ST1610, ST1611 and ST1612) were described for the first time in this study. ConclusionThe wide variety of new alleles and new STs detected in the present study indicates a divergent population compared to studies that are carried out in the clinical environment and points to an even larger genetic diversity within the species than was anticipated. Significance and Impact of the StudyA number of the environmental isolates represented multidrug-resistant strains, a phenotype that has been more commonly reported for clinical isolates of A. baumannii; the detection of several -lactamase encoding genes in the investigated isolates is of great concern suggesting that there is a large reservoir of these resistance genes in the environment.