Insights into a novel Tn4401 deletion (Tn4401i) in a multidrug-resistant Klebsiella pneumoniae clinical strain belonging to the high-risk clonal group 258 producing KPC-2

Plasmid genomic epidemiology of blaKPC carbapenemase-producing Enterobacterales in Canada, 2010-2021

Carbapenems are considered last-resort antibiotics for the treatment of infections caused by multidrug-resistant Enterobacterales, but carbapenem resistance due to acquisition of carbapenemase genes is a growing threat that has been reported worldwide. Klebsiella pneumoniae carbapenemase (blaKPC) is the most common type of carbapenemase in Canada and elsewhere; it can hydrolyze penicillins, cephalosporins, aztreonam, and carbapenems and is frequently found on mobile plasmids in the Tn4401 transposon. This means that alongside clonal expansion, blaKPC can disseminate through plasmid- and transposon-mediated horizontal gene transfer. We applied whole genome sequencing to characterize the molecular epidemiology of 829 blaKPC carbapenemase-producing isolates collected by the Canadian Nosocomial Infection Surveillance Program from 2010 to 2021. Using a combination of short-read and long-read sequencing, we obtained 202 complete and circular blaKPC-encoding plasmids. Using MOB-suite, 10 major plasmid clusters were identified from this data set which represented 87% (175/202) of the Canadian blaKPC-encoding plasmids. We further estimated the genomic location of incomplete blaKPC-encoding contigs and predicted a plasmid cluster for 95% (603/635) of these. We identified different patterns of carbapenemase mobilization across Canada related to different plasmid clusters, including clonal transmission of IncF-type plasmids (108/829, 13%) in K. pneumoniae clonal complex 258 and novel repE(pEh60-7) plasmids (44/829, 5%) in Enterobacter hormaechei ST316, and horizontal transmission of IncL/M (142/829, 17%) and IncN-type plasmids (149/829, 18%) across multiple genera. Our findings highlight the diversity of blaKPC genomic loci and indicate that multiple, distinct plasmid clusters have contributed to blaKPC spread and persistence in Canada.

Description of a new non-Tn4401 element (NTEKPC-IIe) harboured on IncQ plasmid in Citrobacter werkmanii from recreational coastal water

OBJECTIVES

Here we describe an IncQ1-like plasmid carrying blaKPC-2 in a new non-Tn4401 element found in Citrobacter werkmanii recovered from coastal water.

METHODS

In vitro and in silico approaches were used to assess antimicrobial resistance determinants, as well as blaKPC-2 vicinities.

RESULTS

The LB-887 isolate showed a multidrug-resistant phenotype and was identified as C. werkmanii. Resistome analysis identified further acquired resistance determinants to β-lactams, aminoglycosides, sulphonamides/trimethoprim, tetracyclines, chloramphenicol, macrolides, rifampicin and fluoroquinolones. Plasmidome included incompatibility groups IncA, IncC2, IncR, Col and IncQ families. The blaKPC-2 was inserted on a new variant of NTEKPC-II, called here NTEKPC-IIe, carried by an InQ1-like plasmid of 7930 kb (pKPC-LB887). NTEKPC-IIe differed from NTEKPC-IId by the complete absence of ISKpn6-tnpA. The InQ1-like backbone harbouring this element had been described in Enterobacterales recovered from clinical and environmental settings.

CONCLUSION

Unravelling genetic structures related to blaKPC dissemination in different settings may provide clues on the main forces driving evolution of this important resistance determinant. Indeed, the occurrence of blaKPC in a new NTEKPC variant from an environmental source highlights the ongoing evolution of this mobile genetic element. In addition, blaKPC carriage on a small and highly mobilizable IncQ plasmid in C. freundii complex from recreational water, similar to others found in clinical isolates, may suggest its relevance for blaKPC-2 dissemination among different compartments.

Molecular Analysis of blaKPC-2-Harboring Plasmids: Tn4401a Interplasmid Transposition and Tn4401a-Carrying ColRNAI Plasmid Mobilization from Klebsiella pneumoniae to Citrobacter europaeus and Morganella morganii in a Single Patient

The spread of Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales is a public health concern. KPC-encoding blaKPC is predominantly spread by strains of a particular phylogenetic lineage, clonal group 258, but can also be spread by horizontal transfer of blaKPC-carrying plasmids. Here, we report the transfer of a blaKPC-2-harboring plasmid via mobilization from K. pneumoniae to Citrobacter freundii complex and Morganella morganii strains in a single patient. We performed draft whole-genome sequencing to analyze 20 carbapenemase-producing Enterobacterales strains (15 of K. pneumoniae, two of C. freundii complex, and three of M. morganii) and all K. pneumoniae strains using MiSeq and/or MinION isolated from a patient who was hospitalized in New York and Montreal before returning to Japan. All strains harbored blaKPC-2-containing Tn4401a. The 15 K. pneumoniae strains each belonged to sequence type 258 and harbored a Tn4401a-carrying multireplicon-type plasmid, IncN and IncR (IncN+R). Three of these K. pneumoniae strains also possessed a Tn4401a-carrying ColRNAI plasmid, suggesting that Tn4401a underwent interplasmid transposition. Of these three ColRNAI plasmids, two and one were identical to plasmids harbored by two Citrobacter europaeus and three M. morganii strains, respectively. The Tn4401a-carrying ColRNAI plasmids were each 23,753 bp long and incapable of conjugal transfer via their own genes alone, but they mobilized during the conjugal transfer of Tn4401a-carrying IncN+R plasmids in K. pneumoniae. Interplasmid transposition of Tn4401a from an IncN+R plasmid to a ColRNAI plasmid in K. pneumoniae and mobilization of Tn4401a-carrying ColRNAI plasmids contributed to the acquisition of blaKPC-2 in C. europaeus and M. morganii. IMPORTANCE Plasmid transfer plays an important role in the interspecies spread of carbapenemase genes, including the Klebsiella pneumoniae carbapenemase (KPC)-coding gene, blaKPC. We conducted whole-genome sequencing (WGS) analysis and transmission experiments to analyze blaKPC-2-carrying mobile genetic elements (MGEs) between the blaKPC-2-harboring K. pneumoniae, Citrobacter europaeus, and Morganella morganii strains isolated from a single patient. blaKPC-2 was contained within an MGE, Tn4401a. WGS of blaKPC-2-carrying K. pneumoniae, C. europaeus, and M. morganii strains isolated from one patient revealed that Tn4401a-carrying ColRNAI plasmids were generated by plasmid-to-plasmid transfer of Tn4401a from a multireplicon-type IncN and IncR (IncN+R) plasmid in K. pneumoniae strains. Tn4401a-carrying ColRNAI plasmids were incapable of conjugal transfer in C. europaeus and M. morganii but mobilized from K. pneumoniae to a recipient Escherichia coli strain during the conjugal transfer of Tn4401a-carrying IncN+R plasmid. Therefore, Tn4401a-carrying ColRNAI plasmids contributed to the acquisition of blaKPC-2 in C. europaeus and M. morganii.

Within patient genetic diversity of blaKPC harboring Klebsiella pneumoniae in a Colombian hospital and identification of a new NTEKPC platform

Resistance to carbapenems in Klebsiellapneumoniae 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 bla_KPC 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 bla_KPC—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 bla_KPC—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 bla_KPC was mobilized by two Tn3-like unrelated platforms: Tn4401b (ST258) and Tn6454 (ST504 and ST846), a new NTE_KPC-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 bla_KPC post-endemic dissemination in Colombia, different KPC-Kp clones (mostly non-CC258) have emerged due to integration of the single bla_KPC 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.

Emergence of New Non-Clonal Group 258 High-Risk Clones among Klebsiella pneumoniae Carbapenemase-Producing K. pneumoniae Isolates, France

The worldwide spread of Klebsiella pneumoniae carbapenemase–producing Klebsiella pneumoniae (KPC-Kp) isolates was reported to be caused by dissemination of 1 clonal complex (i.e., clonal group [CG] 258, which includes sequence types [STs] 258 and 512). We conducted whole-genome sequencing and epidemiologic analysis of all KPC-Kp isolates in France in 2018 and found that new successful high-risk clones of ST147, ST307, ST231, and ST383 are now the main drivers of bla_KPC genes. The bla_KPC genes were mostly carried by Tn4401a and Tn4401d structures and a new non–Tn4401 element. Our epidemiologic investigations showed that the emergence of these non-CG258 KPC-Kp isolates in France was linked to dissemination of these clones from Portugal. Thus, KPC-Kp epidemiology has changed in Europe, at least in several non–KPC-endemic countries of western Europe, such as France and Portugal, where CG258 is not the most prevalent clone.

Mobile Carbapenemase Genes in Pseudomonas aeruginosa

Carbapenem-resistant Pseudomonas aeruginosa is one of the major concerns in clinical settings impelling a great challenge to antimicrobial therapy for patients with infections caused by the pathogen. While membrane permeability, together with derepression of the intrinsic beta-lactamase gene, is the global prevailing mechanism of carbapenem resistance in P. aeruginosa, the acquired genes for carbapenemases need special attention because horizontal gene transfer through mobile genetic elements, such as integrons, transposons, plasmids, and integrative and conjugative elements, could accelerate the dissemination of the carbapenem-resistant P. aeruginosa. This review aimed to illustrate epidemiologically the carbapenem resistance in P. aeruginosa, including the resistance rates worldwide and the carbapenemase-encoding genes along with the mobile genetic elements responsible for the horizontal dissemination of the drug resistance determinants. Moreover, the modular mobile elements including the carbapenemase-encoding gene, also known as the P. aeruginosa resistance islands, are scrutinized mostly for their structures.

Population Structure of KPC-2-Producing Klebsiella pneumoniae Isolated from Surveillance Rectal Swabs in Brazil

KPC-producing Klebsiella pneumoniae (KPC-Kp) has become an important public health issue. The previous intestinal colonization by KPC-Kp has been an important risk factor associated with the progression to infections. The objective of this study was to assess the genetic characterization of KPC-Kp isolates recovered from human rectal swabs in Brazil. We selected 102 KPC-Kp isolates collected during 2009-2013 in 11 states. Antimicrobial susceptibility was determined by disk diffusion, E-test, and broth microdilution. The resistance and virulence genes were investigated by PCR. Molecular typing was performed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The isolates were mostly resistant to β-lactams, sulfonamides, chloramphenicol, quinolones, and aminoglycosides but susceptible to fosfomycin/trometamol, polymyxin B, and tigecycline. The bla_KPC-2 was mostly associated with Tn4401b. Besides that, the isolates carried bla_CTX-M, bla_SHV, bla_TEM, and aac(6')-Ib in high frequency and aac(3')IIa and qnr genes in moderate frequency. The PFGE revealed 26 pulsotypes and MLST performed in representative strains revealed 23 sequence types, 45% belonging to clonal complex 258 (CC258). Isolates of CC258 were found in all states. Seventy percent of the 102 KPC-Kp isolates belonged to CC258-associated pulsotypes. We describe the dissemination of KPC-2-Kp associated with Tn4401b belonging to CC258 colonizing patients in Brazil, which is also prevalent in infected patients, suggesting a clear colonization-infection correlation.