Emergence of Klebsiella pneumoniae carbapenemase-producing Proteus mirabilis in Hangzhou, China

Background Carbapenems are used to treat severe infections caused by multi-drug-resistant organisms, however, the emergence of carbapenem-resistant bacterial isolates is becoming an increasing therapeutic challenge. Since the first Klebsiella （K.） pneumoniae carbapenemase （KPC）-producing K. pneumoniae was reported in 2001, KPC-producing isolates have been found increasingly, specially in Enterobacteriaceae. The aim of this study was to characterize the mechanisms of a carbapenem-resistant Proteus （P.） mirabilis. Methods A carbapenem-resistant P. mirabilis isolate was recovered from pleural drainage fluid of a patient admitted to surgical intensive care unit. Antimicrobial susceptibility testing of the isolate was performed by disk diffusion according to Clinical and Laboratory Standards Institute guidelines, and subsequent minimal inhibitory concentrations were determined with the E-test. Amplification of the blaKPC gene generated a positive band and the PCR products were sequenced subsequently. The plasmid of the isolate was extracted and was successfully transformed into Escherichia （E.） coli DH5a. Results The P. mirabilis isolate was resistant to all detected antimicrobial agents except tigecycline. KPC-2 was confirmed by DNA sequence analysis. The transformant E. coil was resistant to carbapenems. Further study demonstrated that upstream and downstream regions of b/aKPC-2 were identical to that observed in K. pneumoniae submitted to GenBank from China in 2007. Conclusion Carbapenem resistance in the P. mirabilis isolate in this study is mainly due to production of KPC-2.

An Outbreak of Infections Caused by a Klebsiella pneumoniae ST11 Clone Coproducing Klebsiella pneumoniae Carbapenemase-2 and RmtB in a Chinese Teaching Hospital

Background： Klebsiellapneumoniae carbapenemase （KPC）-producing K. pneumoniae bacteria, which cause serious disease outbreaks worldwide, was rarely detected in Xiangya Hospital, prior to an outbreak that occurred from August 4, 2014, to March 17, 2015. The aim of this study was to analyze the epidemiology and molecular characteristics of the K. pneumoniae strains isolated during the outbreak. Methods： Nonduplicate carbapenem-resistant K. pneumoniae isolates were screened for blanc,＂ and multiple other resistance determinants using polymerase chain reaction. Subsequent studies included pulsed-field gel electrophoresis （PFGE）, multilocus sequence typing, analysis of plasmids, and genetic organization ofblaKPC-2 locus. Results： Seventeen blaKPC-2-positive K. pneumoniae were identified. A wide range of resistant determinants was detected. Most isolates （88.2%） coharbored blaKPC-2 and rmtB in addition to other resistance genes, including biaSHV-1, blaTEM-1, and aac（3）-lla. The blaKPC-2 and rmtB genes were located on the conjugative IncFIB-type plasmid. Genetic organization of blaKPC-2 locus in most strains was consistent with that of the plasmid pKP048. Four types （A l, A2, A3, and B） were detected by PFGE, and Type A1, an ST11, was the predominant PFGE type. A novel K. pneumoniae sequence type （ST1883） related to STI 1 was discovered. Conclusions： These isolates in our study appeared to be clonal and STI 1 K. pneumoniae was the predominant clone attributed to the outbreak. Coharbing of blaKPC-2 and rmtB, which were located on a transferable plasmid, in clinical K. pneumoniae isolates may lead to the emergence of a new pattern of drug resistance.

Emergence of Klebsiella pneumoniae carbapenemase-producing Escherichia coli sequence type 131 in Hangzhou, China

Background Klebsiella pneumoniae carbapenemase （KPC）-producing Escherichia （E.） coil has been reported in China since 2008.However,there is no information about the molecular epidemiology of KPC-producing E.coil in China.In this study,we aimed to investigate the sequence type （ST） and characteristics of KPC-producing E.coil isolates in China.Methods Three carbapenem-resistant isolates of E.coil （E1,E2,and E3） from one teaching hospital in Hangzhou covering a one year period were analyzed.Antibiotic susceptibility was determined by Etest.Pulsed-field gel electrophoresis （PFGE） and multilocus sequence typing （MLST） were used for epidemiological analysis.The genetic structure around blaKPC,the major plasmid incompatibility typing,and the identification of 3-lactamase gene types were performed by PCR and the positive products were subsequently sequenced.Plasmids were analyzed by transformation,restriction,and Southern blotting.Results PFGE demonstrated that patterns of isolates E1 and E2 were clonally-related and designated as patterns A1 and A2; pattern of isolate E3 was different and designated as pattern B.MLST analysis showed that the three isolates displayed one common sequence type ST131.The identification of bla gene types by PCR and sequencing showed that blaKPC-2,blaCTX-M-14,and blaTEM-1 were detected in all three isolates.All three isolates carried a KPC-2-encoding plasmid of the IncN replicon.Plasmid analysis and hybridization experiments showed that the isolates were found simultaneously to carry two or four plasmids.The blaKPc-2 gene in E1 and E2 was located in a plasmid with size of ca.50 kb.However,the blaKPC-2 gene in E3 was located in a plasmid with size of ca.130 kb.Conclusions E.coil ST131 with KPC-2 β-1actamase has emerged in China,which enlarges the geographical area where the ST131 KPC-oroducing E.coil strains have diffused.

A comparative study of intestinal Pseudomonas aeruginosa in healthy individuals and ICU inpatients

The human intestinal tract is considered the most important reservoir of the opportunistic pathogens,including Pseudomonas aeruginosa,which is often overlooked but critical due to its antimicrobial resistance and virulence.Public health interventions to control this pathogen require a comprehensive understanding of its epidemiology and genomics.In the current study,we identified P.aeruginosa strains from 2,605 fecal samples collected between 2021 to 2022.Among these samples,574 were from ICU inpatients in Zhejiang province,while 2,031 were obtained from healthy individuals residing in ten different provinces in China.The prevalence of P.aerugi-nosa intestinal carriage was found to be higher in ICU inpatients(10.28%,95%CI:7.79%-12.76%)than that in healthy individuals(3.99%,81/2,031,95%CI:3.14%-4.84%).Similarly,the prevalence of carbapenem-resistant P.aeruginosa(CRPA)was higher in ICU inpatients(32.2%)compared to healthy individuals(7.41%).The population structure analy-sis of our isolates revealed a predominantly non-clonal distribution,with 41 distinct sequence types identified among 59 P.aeruginosa isolates from ICU inpatients and 38 different STs among 81 P.aeruginosa isolates from healthy individuals.These findings suggest that the individual acquisition of P.aeruginosa is more frequent than patient-to-patient transmission,as evidenced by the polyclonal population structure.Antimicrobial susceptibility testing and genome analysis indicated that P.aeruginosa strains from ICU inpatients exhibited significantly higher resistance rates to most antimicrobials and harbored a greater number of acquired resistance genes compared to strains from healthy individuals.Notably,in ICU inpatients,we identified three isolates of ST463,all of which shared the conserved Tn3-TnpR-ISKpn8-blaKPC-ISKpn6 genetic context.Additionally,five isolates carrying the qacE gene were also identified,these findings suggest that small-scale transmission events may still occur within the ICU setting,posing significant challenges for clinical management.With regard to virulence factors,we observed similar profiles between the two groups,except for phzA2,phzB2,and pilA,which were statistically higher in isolates from healthy individuals.This may be because the accumulating resistance mutations in ICU-derived P.aeruginosa are linked to a decrease in virulence.