Genetic Basis of Antimicrobial Resistant Gram-Negative Bacteria Isolated From Bloodstream in Brazil

Multidrug-resistant microorganisms are a well-known global problem, and gram-negative bacilli are top-ranking. When these pathogens are associated with bloodstream infections (BSI), outcomes become even worse. Here we applied whole-genome sequencing to access information about clonal distribution, resistance mechanism diversity and other molecular aspects of gram-negative bacilli (GNB) isolated from bloodstream infections in Brazil. It was possible to highlight international high-risk clones circulating in the Brazilian territory, such as CC258 for Klebsiella pneumoniae, ST79 for Acinetobacter baumannii and ST233 for Pseudomonas aeruginosa. Important associations can be made such as a negative correlation between CRISPR-Cas and K. pneumoniae CC258, while the genes bla(TEM), bla(KPC) and bla(CTX−M) are highly associated with this clone. Specific relationships between A. baumannii clones and bla(OXA−51) variants were also observed. All P. aeruginosa ST233 isolates showed the genes bla(VIM) and bla(OXA486). In addition, some trends could be identified, where a new P. aeruginosa MDR clone (ST3079), a novel A. baumannii clonal profile circulating in Brazil (ST848), and important resistance associations in the form of bla(VIM−2) and bla(IMP−56) being found together in one ST233 strain, stand out. Such findings may help to develop approaches to deal with BSI and even other nosocomial infections caused by these important GNB.