Project description:Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae have emerged as major nosocomial pathogens. bla(KPC), commonly located on Tn4401, is found in Gram-negative bacterial strains, with the two most common variants, bla(KPC-2) and bla(KPC-3), identified in plasmids with diverse genetic backgrounds. In this study, we examined bla(KPC-4)- and bla(KPC-5)-bearing plasmids recovered from two K. pneumoniae strains, which were isolated from a single New Jersey hospital in 2005 and 2006, respectively. IncN plasmid pBK31551 is 84 kb in length and harbors bla(KPC-4), bla(TEM-1), qnrB2, aac(3)-Ib, aph(3')-I, qacF, qacE?1, sul1, and dfrA14, which confer resistance to ?-lactams, quinolones, aminoglycosides, quaternary ammonium compounds, and co-trimoxazole. The conserved regions within pBK31551 are similar to those of other IncN plasmids. Surprisingly, analysis of the Tn4401 sequence revealed a large IS110- and Tn6901-carrying element (8.3 kb) inserted into the istA gene, encoding glyoxalase/bleomycin resistance, alcohol dehydrogenase, and S-formylglutathione hydrolase. Plasmid pBK31567 is 47 kb in length and harbors bla(KPC-5), dfrA5, qacE?1, and sul1. pBK31567 belongs to a novel IncX subgroup (IncX5) and possesses a highly syntenic plasmid backbone like other IncX plasmids; however, sequence similarity at the nucleotide level is divergent. The bla(KPC-5) gene is carried on a Tn4401 element and differs from the genetic environment of bla(KPC-5) described in Pseudomonas aeruginosa strain P28 from Puerto Rico. This study underscores the genetic diversity of multidrug-resistant plasmids involved in the spread of bla(KPC) genes and highlights the mobility and plasticity of Tn4401. Comparative genomic analysis provides new insights into the evolution and dissemination of KPC plasmids belonging to different incompatibility groups.
Project description:This study aimed to characterize carbapenem-resistant Klebsiella pneumoniae (CR-KP) co-harboring bla KPC-2-carrying plasmid and pLVPK-like virulence plasmid. Between December 2017 and April 2018, 24 CR-KP isolates were recovered from 24 patients with bacteremia. The mortality was 66.7%. Pulsed-field gel electrophoresis and multilocus sequence typing results indicated four clusters, of which cluster A (n = 21, 87.5%) belonged to ST11 and the three remaining isolates (ST412, ST65, ST23) had different pulsotypes (cluster B, C, D). The bla KPC-2-carrying plasmids all belonged to IncFIIK type, and the size ranged from 100 to 390 kb. Nineteen strains (79.2%) had a 219-kb virulence plasmid possessed high similarity to pLVPK from CG43 with serotype K2. Two strains had a 224-kb virulence plasmid resembled plasmid pK2044 from K. pneumoniae NTUH-K2044(ST23). Moreover, three strains carried three different hybrid resistance- and virulence-encoding plasmids. Conjugation assays showed that both bla KPC-2 and rmpA2 genes could be successfully transferred to E. coli J53 in 62.5% of the strains at frequencies of 4.5 × 10-6 to 2.4 × 10-4, of which three co-transferred bla KPC-2 along with rmpA2 in large plasmids. Infection assays in the Galleria mellonella model demonstrated the virulence level of these isolates was found to be consistently higher than that of classic Klebsiella pneumoniae. In conclusion, CR-KP co-harboring bla KPC-2-carrying plasmid and pLVPK-like virulence plasmid were characterized by multi-drug resistance, enhanced virulence, and transferability, and should, therefore, be regarded as a real superbug that could pose a serious threat to public health. Hence, heightened efforts are urgently needed to avoid its co-transmission of the virulent plasmid (gene) and resistant plasmid (gene) in clinical isolates.
Project description:Klebsiella pneumoniae carbapenemase (KPC) actively hydrolyzes carbapenems, antibiotics often used a last-line treatment for multidrug-resistant bacteria. KPC clinical relevance resides in its widespread dissemination. In this work, we report the genomic context of KPC coding genes blaKPC-2, blaKPC-3 and blaKPC-30 in multidrug-resistant Klebsiellapneumoniae isolates from Brazil. Plasmids harboring blaKPC-3 and blaKPC-30 were identified. Fifteen additional carbapenem-resistant K. pneumoniae isolates were selected from the same tertiary hospital, collected over a period of 8 years. Their genomes were sequenced in order to evaluate the prevalence and dissemination of blaKPC-harboring plasmids. We found that blaKPC genes were mostly carried by one of two isoforms of transposon Tn4401 (Tn4401a or Tn4401b) that were predominantly located on plasmids highly similar to the previously described plasmid pKPC_FCF3SP (IncN). The identified pKPC_FCF3SP-like plasmids carried either blaKPC-2 or blaKPC-30. Two K. pneumoniae isolates harbored pKpQIL-like (IncFII) plasmids, only recently identified in Brazil; one of them harbored blaKPC-3 in a Tn4401a transposon. Underlining the risk of horizontal spread of KPC coding genes, this study reports the prevalence of blaKPC-2 and the recent spread of blaKPC-3, and blaKPC-30, in association with different isoforms of Tn4401, together with high synteny of plasmid backbones among isolates studied here and in comparison with previous reports.
Project description:The study aimed to characterize plasmids mediating carbepenem resistance in Klebsiella pneumoniae in Pretoria, South Africa. We analysed 56 K. pneumoniae isolates collected from academic hospital around Pretoria. Based on phenotypic and molecular results of these isolates, 6 representative isolates were chosen for further analysis using long reads sequencing platform. We observed multidrug resistant phenotype in all these isolates, including resistance to aminoglycosides, tetracycline, phenicol, fosfomycin, floroquinolones, and beta-lactams antibiotics. The blaOXA-48/181 and blaNDM-1/7 were manily the plasmid-mediated carbapenemases responsible for carbapenem resistance in the K. pneumoniae isolates in these academic hospitals. These carbapenemase genes were mainly associated with plasmid replicon groups IncF, IncL/M, IncA/C, and IncX3. This study showed plasmid-mediated carbapenemase spread of blaOXA and blaNDM genes mediated by conjugative plasmids in Pretoria hospitals.
Project description:A carbapenem-resistant isolate of Klebsiella pneumoniae producing class A carbapenemase KPC-2 was identified in Zhejiang, China. The KPC-2 gene was located on an approximately 60-kb plasmid in a genetic environment partially different from that of blaKPC-2 in the isolates from the United States and Colombia.
Project description:Carbapenems and tigecycline are two important classes of antimicrobial agents to treat the infections caused by Enterobacterales. Here, we reported a plasmid carrying both bla IMP-26 and tet(A) variant in clinical Klebsiella pneumoniae KP-1572. MIC results showed that K. pneumonia KP-1572 was resistant to a wide range of antimicrobials. The bla IMP-26 and tet(A) variant were located on an identical plasmid, which was indicated by S1-PFGE and southern blotting hybridization and can be successfully transferred by electroporation. Whole-plasmid sequencing and analysis revealed that a 142,993-bp-sized plasmid, designated pIMP1572, contains an IncFIIk backbone and a variable region harboring bla IMP-26 and tet(A) variant. The plasmid pIMP1572 was apparently originated from a tet(A)-carrying IncFIIk plasmid but with a deletion length of 6,216-bp and a multiple drug resistance region (MDRR) insertion of 25,259 bp. The plasmid pIMP1572 in the present study represents the first report of the IncFIIk plasmid co-carrying bla IMP and tet(A) variant, which should be monitored.
Project description:The aim of this study was to characterize the genetic context of blaKPC-2 in Pseudomonas aeruginosa sequence type 244 from Brazil. The blaKPC-2 gene was detected in a new small plasmid, pBH6. Complete sequencing revealed that pBH6 was 3,652 bp long and included the Tn3 resolvase and Tn3 inverted repeat (IR), a partial copy of ISKpn6, and a putative ori region but no rep genes. pBH6 replicated stably into Escherichia coli strain DH10B and P. aeruginosa strain PAO.
Project description:The TEM-107 extended-spectrum β-lactamase detected in a Klebsiella pneumoniae clinical isolate had a Gly238Ser substitution compared to the TEM-43 β-lactamase. The MIC of ceftazidime was higher (64 μg/ml) than that of cefotaxime (2 μg/ml) for the isolate. Clavulanic acid reduced the MIC of ceftazidime 64-fold.
Project description:The combination of carbapenem resistance and hypervirulence in Klebsiella pneumoniae is an emerging and urgent threat due to its potential to resist common antibiotics and cause life-threatening infections in healthy hosts. This study aimed to evaluate the activity of clinically relevant antibiotic regimens against carbapenem-resistant K. pneumoniae with hypervirulence plasmids and to identify pathways associated with antibiotic tolerance using transcriptomics. We studied two carbapenem-resistant K. pneumoniae isolates, CDI694 and CDI231, both harboring hypervirulence plasmids. Time-kill and dynamic one-compartment pharmacokinetic/pharmacodynamic assays were used to assess ceftazidime/avibactam-based therapies. RNAseq was performed following 48 h of antibiotic exposure. Closed genomes of CDI694 and CDI231 were obtained; each isolate harbored carbapenem-resistance and hypervirulence (containing rmpA/rmpA2 and iut genes) plasmids. Ceftazidime/avibactam-based regimens were bactericidal, though both isolates continued to grow in the presence of antibiotics despite no shifts in MIC. Transcriptomic analyses suggested that perturbations to cell respiration, carbohydrate transport, and stress-response pathways contributed to the antibiotic tolerance in CDI231. Genes associated with hypervirulence and antibiotic resistance were not strongly impacted by drug exposure except for ompW, which was significantly downregulated. Treatment of carbapenem-resistant K. pneumoniae harboring hypervirulence plasmids with ceftazidime/avibactam-based regimens may yield a tolerant population due to altered transcription of multiple key pathways.