To track stepwise changes in genetic diversity and antimicrobial resistance in rapidly evolving OXA-232-producing Klebsiella pneumoniae ST14, an emerging carbapenem-resistant high-risk clone, in clinical settings.Twenty-six K. pneumoniae ST14 isolates were collected by the Korean Nationwide Surveillance of Antimicrobial Resistance system over the course of 1 year. Isolates were subjected to whole-genome sequencing and MIC determinations using 33 antibiotics from 14 classes.Single-nucleotide polymorphism (SNP) typing identified 72 unique SNP sites spanning the chromosomes of the isolates, dividing them into three clusters (I, II and III). The initial isolate possessed two plasmids with 18 antibiotic-resistance genes, including blaOXA-232, and exhibited resistance to 11 antibiotic…
Although antiretroviral therapy (ART) is highly effective at suppressing HIV-1 replication, the virus persists as a latent reservoir in resting CD4+ T cells during therapy. This reservoir forms even when ART is initiated early after infection, but the dynamics of its formation are largely unknown. The viral reservoirs of individuals who initiate ART during chronic infection are generally larger and genetically more diverse than those of individuals who initiate therapy during acute infection, consistent with the hypothesis that the reservoir is formed continuously throughout untreated infection. To determine when viruses enter the latent reservoir, we compared sequences of replication-competent viruses…
The increased prevalence of antimicrobial resistance (AMR) among Enterobacteriaceae has had major clinical and economic impacts on human medicine. Many of the multidrug-resistant (multiresistant) Enterobacteriaceae found in humans are community acquired, and some of them are possibly linked to food animals (i.e., livestock raised for meat and dairy products). In this study, we examined whether numerically dominant commensal Escherichia coli strains from humans (n?=?63 isolates) and domestic animals (n?=?174 isolates) in the same community and with matching phenotypic AMR patterns were clonally related or shared the same plasmids. We identified 25 multiresistant isolates (i.e., isolates resistant to more than one…
The spread of carbapenemase-producing Enterobacteriaceae (CPE), contributing to widespread carbapenem resistance, has become a global concern. However, the specific dissemination patterns of carbapenemase genes have not been intensively investigated in developing countries, including Myanmar, where NDM-type carbapenemases are spreading in clinical settings. In the present study, we phenotypically and genetically characterized 91 CPE isolates obtained from clinical (n = 77) and environmental (n = 14) samples in Yangon, Myanmar. We determined the dissemination of plasmids harboring genes encoding NDM-1 and its variants using whole-genome sequencing and plasmid analysis. IncFII plasmids harboring blaNDM-5 and IncX3 plasmids harboring blaNDM-4 or blaNDM-7 were…
We characterized 170 complete genome assemblies from clinical Bordetella pertussis isolates representing geographic and temporal diversity in the United States. These data capture genotypic shifts, including increased pertactin deficiency, occurring amid the current pertussis disease resurgence and provide a foundation for needed research to direct future public health control strategies.
Carbapenemase-producing Enterobacteriaceae (CPE) pose a major global health risk. Mobile genetic elements account for much of the increasing CPE burden.To investigate CPE colonization and the impact of antibiotic exposure on subsequent resistance gene dissemination within the gut microbiota using a model to simulate the human colon.Gut models seeded with CPE-negative human faeces [screened with BioMérieux chromID® CARBA-SMART (Carba-Smart), Cepheid Xpert® Carba-R assay (XCR)] were inoculated with distinct carbapenemase-producing Klebsiella pneumoniae strains (KPC, NDM) and challenged with imipenem or piperacillin/tazobactam then meropenem. Resistant populations were enumerated daily on selective agars (Carba-Smart); CPE genes were confirmed by PCR (XCR, Check-Direct CPE Screen…
Ceftriaxone resistance in Neisseria gonorrhoeae is a major public health concern globally because a high-dose (1?g) injection of ceftriaxone is the only remaining option for empirical monotherapy of gonorrhoea. The ceftriaxone-resistant gonococcal strain FC428, cultured in Osaka in 2015, is suspected to have spread nationally and internationally. We describe the complete finished genomes of FC428 and two closely related isolates from Osaka in 2015, and examine the genomic epidemiology of these isolates plus three ceftriaxone-resistant gonococcal isolates from Osaka and Hyogo in 2016-17 and four ceftriaxone-resistant gonococcal isolates cultured in 2017 in Australia, Canada and Denmark.During 2015-17, we identified six…
From 2012 to 2015, a sudden significant increase in vancomycin-resistant (vanA) Enterococcus faecium (VREfm) was observed in the Capital Region of Denmark. Clonal relatedness of VREfm and vancomycin-susceptible E. faecium (VSEfm) was investigated, transmission events between hospitals were identified and the pan-genome and plasmids from the largest VREfm clonal group were characterized.WGS of 1058 E. faecium isolates was carried out on the Illumina platform to perform SNP analysis and to identify the pan-genome. One isolate was also sequenced on the PacBio platform to close the genome. Epidemiological data were collected from laboratory information systems.Phylogeny of 892 VREfm and 166 VSEfm…
The past two decades have witnessed an alarming expansion of staphylococcal disease caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The factors underlying the epidemic expansion of CA-MRSA lineages such as USA300, the predominant CA-MRSA clone in the United States, are largely unknown. Previously described virulence and antimicrobial resistance genes that promote the dissemination of CA-MRSA are carried by mobile genetic elements, including phages and plasmids. Here, we used high-resolution genomics and experimental infections to characterize the evolution of a USA300 variant plaguing a patient population at increased risk of infection to understand the mechanisms underlying the emergence of genetic elements…
Genetic exchange enables parasites to rapidly transform disease phenotypes and exploit new host populations. Trypanosoma cruzi, the parasitic agent of Chagas disease and a public health concern throughout Latin America, has for decades been presumed to exchange genetic material rarely and without classic meiotic sex. We present compelling evidence from 45 genomes sequenced from southern Ecuador that T. cruzi in fact maintains truly sexual, panmictic groups that can occur alongside others that remain highly clonal after past hybridization events. These groups with divergent reproductive strategies appear genetically isolated despite possible co-occurrence in vectors and hosts. We propose biological explanations for…
After initiating antiretroviral therapy (ART), a rapid decline in HIV viral load is followed by a long period of undetectable viremia. Viral outgrowth assay suggests the reservoir continues to decline slowly. Here, we use full-length sequencing to longitudinally study the proviral landscape of four subjects on ART to investigate the selective pressures influencing the dynamics of the treatment-resistant HIV reservoir. We find intact and defective proviruses that contain genetic elements favoring efficient protein expression decrease over time. Moreover, proviruses that lack these genetic elements, yet contain strong donor splice sequences, increase relatively to other defective proviruses, especially among clones. Our…