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Resistance to carbapenems in Klebsiella pneumoniae has been mostly related with the worldwide dissemination of KPC, largely due to the pandemic clones belonging to the complex clonal (CC) 258. To unravel blaKPC post-endemic clinical impact, here we describe clinical characteristics of 68 patients from a high complexity hospital, and the molecular and genetic characteristics of their 139 blaKPC—K. pneumoniae (KPC-Kp) isolates. Of the 26 patients that presented relapses or reinfections, 16 had changes in the resistance profiles of the isolates recovered from the recurrent episodes. In respect to the genetic diversity of KPC-Kp isolates, PFGE revealed 45 different clonal complexes (CC). MLST for 12 representative clones showed ST258 was present in the most frequent CC (23.0%), however, remaining 11 representative clones belonged to non-CC258 STs (77.0%). Interestingly, 16 patients presented within-patient genetic diversity of KPC-Kp clones. In one of these, three unrelated KPC-Kp clones (ST258, ST504, and ST846) and a blaKPC—K. variicola isolate (ST182) were identified. For this patient, complete genome sequence of one representative isolate of each clone was determined. In K. pneumoniae isolates blaKPC was mobilized by two Tn3-like unrelated platforms: Tn4401b (ST258) and Tn6454 (ST504 and ST846), a new NTEKPC-IIe transposon for first time characterized also determined in the K. variicola isolate of this study. Genome analysis showed these transposons were harbored in different unrelated but previously reported plasmids and in the chromosome of a K. pneumoniae (for Tn4401b). In conclusion, in the blaKPC post-endemic dissemination in Colombia, different KPC-Kp clones (mostly non-CC258) have emerged due to integration of the single blaKPC gene in new genetic platforms. This work also shows the intra-patient resistant and genetic diversity of KPC-Kp isolates. This circulation dynamic could impact the effectiveness of long-term treatments.

Endothelial activation and alteration during dengue virus (DENV) infection are multifactorial events; however, the role of extracellular vesicles (EVs) in these phenomena is not known. In the present study, we characterized the EVs released by DENV-2 infected U937 macrophage cell line and evaluated the changes in the physiology and integrity of the EA.hy926 endothelial cells exposed to them. U937 macrophages were infected, supernatants were collected, and EVs were purified and characterized. Then, polarized endothelial EA.hy926 cells were exposed to the EVs for 24 h, and the transendothelial electrical resistance (TEER), monolayer permeability, and the expression of tight junction and adhesion proteins and cytokines were evaluated. The isolated EVs from infected macrophages corresponded to exosomes and apoptotic bodies, which contained the viral NS3 protein and different miRs, among other products. Exposure of EA.hy926 cells to EVs induced an increase in TEER, as well as changes in the expression of VE-cadherin and ICAM in addition leads to an increase in TNF-α, IP-10, IL-10, RANTES, and MCP-1 secretion. These results suggest that the EVs of infected macrophages transport proteins and miR that induce early changes in the physiology of the endothelium, leading to its activation and eliciting a defense program against damage during first stages of the disease, even in the absence of the virus.

Background Pseudomonas aeruginosa Sequence Type 235 is a clone that possesses an extraordinary ability to acquire mobile genetic elements and has been associated with the spread of resistance genes, including genes that encode for carbapenemases. Here, we aim to characterize the genetic platforms involved in resistance dissemination in blaKPC-2-positive P. aeruginosa ST235 in Colombia. Results In a prospective surveillance study of infections in adult patients attended in five ICUs in five distant cities in Colombia, 58 isolates of P. aeruginosa were recovered, of which, 27 (46.6%) were resistant to carbapenems. The molecular analysis showed that 6 (22.2%) and 4 (14.8%) isolates harboured the blaVIM and blaKPC-2 genes, respectively. The four blaKPC-2-positive isolates showed a similar PFGE pulsotype and belonged to ST235. Complete genome sequencing of a representative ST235 isolate shows a unique chromosomal contig of 7097.241 bp with eight different resistance genes identified and five transposons: a Tn6162-like with ant(2″)-Ia, two Tn402-like with ant(3″)-Ia and blaOXA-2 and two Tn4401b with blaKPC-2. All transposons were inserted into the genomic islands. Interestingly, the two Tn4401b copies harbouring blaKPC-2 were adjacently inserted into a new genomic island (PAGI-17) with traces of a replicative transposition process. This double insertion was probably driven by several structural changes within the chromosomal region containing PAGI-17 in the ST235 background. Conclusion This is the first report of a double Tn4401b chromosomal insertion in P. aeruginosa, just within a new genomic island (PAGI-17). This finding indicates once again the great genomic plasticity of this microorganism. Electronic supplementary material The online version of this article (10.1186/s12866-019-1418-6) contains supplementary material, which is available to authorized users.

Staphylococcus aureus pandemic clone USA300 has, in addition to its constitutive arginine catabolism (arc) gene cluster, an arginine catabolism mobile element (ACME) carrying another such cluster, which gives this clone advantages in colonisation and infection. Gene arcR, which encodes an oxygen-sensitive transcriptional regulator, is inside ACME and downstream of the constitutive arc gene cluster, and this situation may have an impact on its activation. Different relative expression behaviours are proven here for arcR ACME and the arc ACME operon compared to the constitutive ones. We also show that the artificially expressed recombinant ArcRACME protein binds to the promoter region of the arc ACME operon; this mechanism can be related to a positive feedback model, which may be responsible for increased anaerobic survival of the USA300 clone during infection-related processes.

© The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. Bacteria that produce the broad-spectrum Carbapenem antibiotic NewDelhi Metallo-b-lactamase (NDM) place a burden on health care systems worldwide, due to the limited treatment options for infections caused by them and the rapid global spread of this antibiotic resistancemechanism.Although it is believed that theassociated resistancegenebla NDM-1 originated inAcinetobacter spp., the role of Enterobacteriaceae in its dissemination remains unclear. In this study, we usedwhole genome sequencing to investigate the dissemination dynamics of blaNDM-1-positive plasmids in a set of 21 clinical NDM-1-positive isolates from Colombia and Mexico (Providencia rettgeri, Klebsiella pneumoniae, and Acinetobacter baumannii) aswell as six representative NDM-1-positive Escherichia coli transconjugants. Additionally, the plasmids from three representative P. rettgeri isolates were sequenced by PacBio sequencing and finished. Our results demonstrate the presence of previously reported plasmids from K. pneumoniae and A. baumannii in different genetic backgrounds and geographically distant locations in Colombia. Three new previously unclassified plasmids were also identified in P. rettgeri from Colombia and Mexico, plus an interesting genetic link between NDM-1-positive P. rettgeri from distant geographic locations (Canada, Mexico, Colombia, and Israel) without any reported epidemiological links was discovered. Finally, we detected a relationship between plasmids present in P. rettgeri and plasmids from A. baumannii and K. pneumoniae. Overall, our findings suggest a Russian dollmodel for the dissemination of blaNDM-1 in LatinAmerica,with P. rettgeri playing a central role in this process, andrevealnewinsights into the evolution and disseminationof plasmids carrying such antibiotic resistance genes.

Background Community-genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) clones are a global concern due to their resistance and increased virulence and their ability to cause infections both hospitalized patients and healthy people in the community. Here, we characterize 32 isolates of a new CG-MRSA clone. These isolates were identified in four cities in Colombia, South America. Methods The isolates were recovered from four different epidemiological and prospective studies that were conducted in several regions of Colombia. Molecular characterizations included multilocus sequence typing; pulsed-field gel electrophoresis; SCCmec, agr and spa typing; and whole-genome sequencing. Results All isolates belonged to ST923 (clonal complex 8), harbouring SCCmec IVa and a spa type t1635 and lacking an arginine catabolism mobile element. The isolates were classified as COL923, were resistant to at least one non-beta-lactam antibiotic, and exhibited high frequencies (>60%) of resistance to macrolides and tetracycline. Using whole-genome sequencing, we found that this new clone harbours novel prophage 3 and beta-island structures and a slightly different pathogenicity island 5. Moreover, isolates belonging to the COL923 clone are grouped in a different clade than USA300 and USA300-LV. Conclusion Our results show the emergence and spread of the COL923 clone in different cities in Colombia. This clone is resistant to several antibiotics and possesses new structures in its mobile genetic elements. Electronic supplementary material The online version of this article (doi:10.1186/s12879-017-2193-3) contains supplementary material, which is available to authorized users.

The dissemination of a clone of community genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) that is related to USA300 has been reported in Latin America. We recently detected isolates of a new clone of CG-MRSA ( spa type t1635 and ACME-negative) that was genetically unrelated to the USA300 clone and that causes infections in children in Colombia. This finding indicates the appearance of a new clone of CG-MRSA in our region.

Six multiresistant, NDM-1-producing Klebsiella pneumoniae strains were recovered from an outbreak that affected six neonatal patients in a Colombian hospital. Molecular analysis showed that all of the isolates harbored the bla NDM-1 , qnrA , and intI1 genes and were clonally related. Multilocus sequence typing showed that the isolates belonged to a new sequence type (ST1043) that was different from the sequence types that had previously been reported. This is the first report of NDM-1-producing isolates in South America.

Summary Objective Community-genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) isolates are known to be more virulent and clinically aggressive in children. The goal of the present study was characterize the molecular epidemiology of MRSA isolates causing infections in Colombian children. Methods An observational and prospective study was conducted between April 2009 and June 2011 at 15 hospitals in Bogota, Colombia. A detailed epidemiological profile was made of 162 children infected with MRSA. The isolates were subjected to antimicrobial susceptibility testing, molecular characterization including 21 virulence genes, SCC mec , spa and agr typing, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). Results Among all isolates included in the study, 85.8% were obtained from patients whose infectious process was initiated in the community; of these, 69,8% occurred in patients without healthcare-associated risk factors. The molecular characterization of the isolates showed a high proportion (95.1%) containing a community-genotype profile with a high prevalence of SCC mec type IV, PVL-positives, and also related to CC8. Most CG-MRSA isolates (143, 92.9%) were genetically related to the pandemic clone USA300, differing by the presence of SCC mec IVc and the absence of the arginine catabolic mobile element (ACME). Conclusions An increase in the frequency of CG-MRSA infections has been reported worldwide. In this study we found that almost all MRSA infections in our pediatric population were caused by community-genotype isolates, supporting the success of the CG-MRSA clones.