The Presence of Virulent and Multidrug-Resistant Clones of Carbapenem-Resistant Klebsiella pneumoniae in Southeastern Brazil.

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) represents an urgent threat to global public health due to the limited therapeutic options available to control this pathogen. This study aims to analyze the molecular epidemiology, antimicrobial resistance and virulence profile of CRKP isolated from patients at hospitals in Southeastern Brazil. KPC and other beta-lactamase genes were detected in all strains, which were also multidrug-resistant (MDR). In addition, 11 strains showed resistance to last-resort antimicrobials, such as colistin and tigecycline. MLST analysis revealed eight different sequence types (ST11, ST37, ST147, ST340, ST384, ST394, ST437, and ST628), being two (ST628 and ST394) reported for the first time in Brazil. Strains belonging to the clonal complex 258 (CC258) "high-risk clones" were prevalent in this study. The Galleria mellonella model showed the emergence of virulent CRKP strains in the healthcare environment and, suggests that colistin-resistant strains were associated with higher virulence. This study shows the presence of virulent CRKP-MDR strains in hospitals across Southeastern Brazil, and draws attention to the presence of highly virulent emerging CRKP-MDR ST628 strains, showing that virulent and resistant clones can emerge quickly, requiring constant monitoring.

Clonal Dissemination of OXA-370-Producing Klebsiella pneumoniae in Rio de Janeiro, Brazil.

Enzymes of the OXA-48 family have become some of the most important beta-lactamases in the world. A new OXA-48 variant (OXA-370) was first described for an Enterobacter hormaechei strain isolated in Rio Grande do Sul (southern region of Brazil) in 2013. Here we report detection of the blaOXA-370 gene in 24 isolates belonging to three Enterobacteriaceae species (22 Klebsiella pneumoniae isolates, 1 Enterobacter cloacae isolate, and 1 Enterobacter aerogenes isolate) collected from five hospitals in Rio de Janeiro, Brazil, in 2013 and 2014. The isolates showed a multidrug resistance profile, and 12.5% were resistant to polymyxin B. Besides blaOXA-370, no other carbapenemase genes were observed by PCR, whereas blaOXA-1 was found in all isolates and 22 isolates (91.6%) possessed blaCTX-M-15. Molecular typing of the K. pneumoniae isolates by pulsed-field gel electrophoresis (PFGE) showed the presence of two clonal groups, i.e., KpA (21 isolates) and KpB (1 isolate). KpA was characterized as sequence type 16 (ST16) and KpB as ST1041 by multilocus sequence typing (MLST). ST16 has been observed for KPC-producing K. pneumoniae in Rio de Janeiro. Plasmid analysis performed with six representative OXA-370-producing isolates showed plasmids harboring the blaOXA-370 gene in all strains, ranging from 25 kb to 150 kb. This study suggests that there is an urgent need to investigate the presence of OXA-370 and dissemination of the K. pneumoniae ST16 clone carrying this gene in Brazil.

Coproduction of NDM-1 and KPC-2 in Enterobacter hormaechei from Brazil.

The most important resistance mechanism against ß-lactam drugs is the production of carbapenemases. In this study, we report the first identification of Klebsiella pneumoniae carbapenemase (KPC)-2 and New Delhi metallo-ß-lactamase (NDM)-1 in Enterobacter hormaechei subps. oharae from Brazil. The detection of carbapenemases was done by phenotypic assays, PCR, and DNA sequencing, whereas the identification was performed by conventional techniques, sequencing of the 16S rDNA gene, and hsp60-genotyping. Molecular typing was performed using pulsed-field gel electrophoresis, and antimicrobial susceptibility was surrogated by the Etest methodology. Using the whole genome sequencing approach, we searched for resistance genes, plasmid incompatibility group genes, and the genetic environment of blaNDM and blaKPC. The plasmid identification was done by restriction digests with the S1 nuclease followed by hybridization using digoxigenin labeled specific probes. The isolate was considered multiresistant, being susceptible to amikacin and polymyxin B. We observed the following resistance genes: blaCTX-M-15, blaACT-7, blaTEM-1, blaOXA-1, aadA1, aadA2, strA, strB, aac(3)-II, qnrB1, and aac(6')-Ib-cr and incompatibility group plasmid genes IncA/C, IncHI2, and IncN. The blaKPC gene was found associated to the transposon Tn4401 isoform b in plasmid with 50 kb (IncN) and blaNDM-1 was flanked by a truncated ISAba125 and bleMBL in plasmid with 160 kb (IncA/C). This study showed the coproduction of two important carbapenemases (KPC-2 and NDM-1) associated with mobile genetic elements of worldwide epidemiological importance (Tn4401 and ISAba125, respectively), reinforcing the idea that urgent measures are necessary to reduce and prevent the spreading of these carbapenemases primarily in the hospital settings.