Dissemination Of Bla Research Articles

Characterization of nontyphoidal Salmonella strains from a tertiary hospital in China: serotype diversity, multidrug resistance, and genetic insights.

Nontyphoidal Salmonella is a significant public health concern due to its ability to cause foodborne illnesses worldwide. This study aims to characterize the nontyphoidal Salmonella strains isolated from patients in China. A total of 19 nontyphoidal Salmonella strains were characterized through serovar identification, antimicrobial susceptibility testing (AST), biofilm formation assessment. Genetic relatedness was determined using pulsed-field gel electrophoresis (PFGE). WGS was employed to decipher the resistance mechanism and to contextualize the S. serovar Mbandaka strains among previously sequenced isolates in China. The biofilm associated mrkA gene was examined by PCR. The predominant serovar identified was S. Enteritidis, followed by S. Mbandaka, S. Thompson, S. Livingston, S. Alachua, and S. Infantis. PFGE analysis indicated a notable genetic similarity among the S. Mbandaka isolates. Phylogenetic analysis suggested that these strains were likely derived from a single source that had persisted in China for over five years. One multidrug resistance (MDR) S. Enteritidis isolate carried a highly transferable IncB/O/K/Z plasmid with bla CTX-M-15. One S. Thompson strain, harboring the mrkABCDF operon in an IncX1 plasmid, isolated from cutaneous lesions, demonstrated robust biofilm formation. However, no mrkABCDF loci were detected in other strains. Our study emphasizes the importance of persisted surveillance and prompt response to Salmonella infections to protect public health. The dissemination of bla CTX-M-15-harboring IncB/O/K/Z plasmid and the spread of virulent mrkABCDF operon among Salmonella in China and other global regions warrant close monitoring.

Investigation of carbapenemases and aminoglycoside modifying enzymes of Acinetobacter baumannii isolates recovered from patients admitted to intensive care units in a tertiary-care hospital in Brazil.

INTRODUCTION: Acinetobacter baumannii are opportunistic bacteria, highly capable of acquiring antimicrobial resistance through the production of carbapenemases and aminoglycoside modifying enzymes (AMEs).METHODS:Carbapenemase and AME genes were investigated in A. baumannii recovered from inpatients of a Brazilian hospital.RESULTS: The key genes found were bla OXA-51-like, the association ISAba1- bla OXA-23-like, and the AME genes aph(3´)-VI, aac(6´)-Ib, aac(3)-Ia, and aph(3´)-Ia. Different clusters spread through the institution wards.CONCLUSIONS:The dissemination of bla OXA-23-like and AME-carrying A. baumannii through the hospital highlights the need for improved preventive measures to reduce the spread of infection.

Epidemic Plasmid Carrying blaCTX-M-15 in Klebsiella penumoniae in China

ObjectiveTo investigate the local epidemiology of Klebsiella penumoniae carrying bla CTX-M-15 in southern China and to characterize the genetic environment of bla CTX-M-15.MethodsPCR and DNA sequencing were used to detect and characterize the genetic contexts of bla CTX-M-15. The clonal relatedness of isolates carrying bla CTX-M-15 was determined by pulse-field gel electrophoresis. Conjugative plasmids carrying bla CTX-M-15 were obtained by mating and were further subject to restriction analysis and replicon typing.ResultsA total of 47CTX-M-15 ESBL-producing isolates of K. pneumoniae were collected from nine hospitals in China from October 2007 to October 2008. Isolates were clustered into various clonal groups. The local spread of bla CTX-M-15 was mainly mediated by one major conjugative plasmid as determined by S1-PFGE and restriction analysis. A 90-kb plasmid belonging to incompatible group FII was the major carrier of bla CTX-M-15 in K. pneumoniae. Except bla TEM-1, the resistance genes such as bla SHV, bla DHA-1, bla OXA-1, qnrB, qnrS, aac(3)-II, and aac(6′)-Ib were not found in the plasmid. In the comparing of conjugative gene sequence, it is 100% identical with the plasmid pKF3–94, which was found in K. pneumonia from Zhejiang province of china previously.Conclusions bla CTX-M-15 was prevalent in K. pneumonia of southern China. The dissemination of bla CTX-M-15 appeared to be due to the horizontal transfer of a 90-kb epidemic plasmid.

Molecular diversity associated with the dissemination of CTX-M-15 beta-lactamase gene in blood culture isolates of Escherichia coli from Edinburgh

Escherichia coli producing the CTX-M-15 β-lactamase are a major cause of infection. We present the characterization of plasmids encoding the CTX-M-15 β-lactamase gene, the genetic environment, and the mode of spread of this gene in blood culture isolates from a single hospital. Blood culture E. coli isolates with extended spectrum β-lactamase (ESBL) phenotype were screened for the presence of the bla(CTX-M) gene, other ESBLs, and aac(6')-Ib-cr genes. The genetic environment of bla(CTX-M) was determined by DNA sequencing. Plasmids were classified by their incompatibility group from polymerase chain reaction (PCR) replicon typing. Plasmid numbers and sizing were assessed by alkaline lysis and S1 nuclease digestion. Genotyping of the strains was determined by pulsed-field gel electrophoresis (PFGE) and ST131 by allele-specific PCR. Seven isolates had bla(CTX-M-15), with these isolates additionally having bla(TEM) (n = 5), bla(OXA) (n = 6), and aac(6')-Ib-cr (n = 6). Insertion sequence ISEcp1 was found upstream of the bla(CTX-M) gene, and in 2 isolates, ISEcp1 was found to be truncated with insertion sequence IS26. Plasmid replicon typing showed bla(CTX-M-15) genes were carried on the IncFII plasmid. All 7 isolates were associated with the O25b-ST131 clone. The PFGE banding pattern showed only 3 isolates were able to demonstrate clonality. This study shows the molecular diversity associated with the dissemination of bla(CTX-M-15) in a single Scottish hospital, which is largely due to horizontal transfer of multi- resistance IncF plasmids rather than clonal spread. It demonstrates that more detailed information is needed to monitor these bacteria to control them appropriately.

"Silent" Dissemination of Klebsiella pneumoniae Isolates Bearing K. pneumoniae Carbapenemase in a Long-term Care Facility for Children and Young Adults in Northeast Ohio

Klebsiella pneumoniae isolates harboring the K. pneumoniae carbapenemase gene (bla(KPC)) are creating a significant healthcare threat in both acute and long-term care facilities (LTCFs). As part of a study conducted in 2004 to determine the risk of stool colonization with extended-spectrum cephalosporin-resistant gram-negative bacteria, 12 isolates of K. pneumoniae that exhibited nonsusceptibility to extended-spectrum cephalosporins were detected. All were gastrointestinal carriage isolates that were not associated with infection. Reassessment of the carbapenem minimum inhibitory concentrations using revised 2011 Clinical Laboratory Standards Institute breakpoints uncovered carbapenem resistance. To further investigate, a DNA microarray assay, PCR-sequencing of bla genes, immunoblotting, repetitive-sequence-based PCR (rep-PCR) and multilocus sequence typing (MLST) were performed. The DNA microarray detected bla(KPC) in all 12 isolates, and bla(KPC-3) was identified by PCR amplification and sequencing of the amplicon. In addition, a bla(SHV-11) gene was detected in all isolates. Immunoblotting revealed "low-level" production of the K. pneumoniae carbapenemase, and rep-PCR indicated that all bla(KPC-3)-positive K. pneumoniae strains were genetically related (≥98% similar). According to MLST, all isolates belonged to sequence type 36. This sequence type has not been previously linked with bla(KPC) carriage. Plasmids from 3 representative isolates readily transferred the bla(KPC-3) to Escherichia coli J-53 recipients. Our findings reveal the "silent" dissemination of bla(KPC-3) as part of Tn4401b on a mobile plasmid in Northeast Ohio nearly a decade ago and establish the first report, to our knowledge, of K. pneumoniae containing bla(KPC-3) in an LTCF caring for neurologically impaired children and young adults.

Prevalence of SXT/R391-like integrative and conjugative elements carrying blaCMY-2 in Proteus mirabilis

To characterize the vectors involved in the dissemination of bla(CMY-2) genes in clinical isolates of Proteus mirabilis collected between 1999 and 2007. Plasmid analysis of 19 P. mirabilis carrying ampC genes was performed by PCR-based replicon typing, S1-PFGE and Southern hybridization with ampC and replicon probes. Isolates that could not be characterized were examined for the presence of SXT/R391-like elements. To demonstrate the involvement of these elements in the dissemination of bla(CMY-2), we performed a PCR amplification of the integrase (int) and toxin/antitoxin (TA) genes from SXT/R391-like integrative conjugative elements (ICEs). Later on, I-Ceu-I PFGE gels and hybridization with bla(CMY-2), int and prfC probes were performed. The genetic organization of bla(CMY-2) was also studied. ampC genes were located on large conjugative plasmids in 11 of the 19 (58%) P. mirabilis studied. However, in eight of these isolates a plasmid was not involved in the mobilization of ampC genes. I-Ceu-I PFGE and hybridization analyses revealed that bla(CMY-2) were chromosomally located in these eight P. mirabilis isolates. The genetic organization of bla(CMY-2) and hybridization analyses revealed that bla(CMY-2) was carried by an ICE almost identical to ICEPmiJpan1 in seven out of these eight isolates. The prevalence of ICEs carrying bla(CMY-2) was surprisingly high [37% (7 out of 19)]. This is the first study giving prevalence data on ICEs carrying bla(CMY-2) genes. These results suggest the need to study these mobile genetic elements in the context of dissemination of acquired AmpC β-lactamases and also of other β-lactamases, such as extended-spectrum β-lactamases and carbapenemases.

Plasmid comparison and molecular analysis of Klebsiella pneumoniae harbouring blaKPC from New York City and Toronto

This study examined Klebsiella pneumoniae clinical isolates and their bla(KPC) plasmids to determine potential relatedness of the isolates and their plasmids harbouring carbapenem resistance mechanisms. K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae from New York City (NYC) (n = 19) and Toronto (n = 2) were typed by PFGE and multilocus sequence typing (MLST). bla(KPC)-harbouring plasmids were transformed into Escherichia coli DH10B(TM), restricted using EcoRI and analysed for bla content and replicon (rep) type. Susceptibility profiles for clinical and transformed strains were determined by automated microbroth dilution using CLSI breakpoints. Outer membrane protein (OMP) genes were analysed by sequencing of ompk35 and ompk36. PFGE analysis identified 17 related strains (≥ 80% similarity; 11 KPC-2, 6 KPC-3) where ST258 was the dominant clonal type. All clinical isolates contained both bla(SHV) and bla(TEM-1) and, with the exception of one isolate, were multidrug resistant (MDR). Transformed KPC plasmids (n = 21) carried TEM-1 (n = 18) and were MDR (n = 5). Three plasmid clusters, repFIIA (n = 10), repR (n = 3) and an unknown type (n = 3), were observed. repFllA plasmids were observed from both NYC and Toronto strains. OMP gene analysis revealed premature stop codons in ompk35 and numerous deletions and insertions in ompk36. The dissemination of bla(KPC) is due both to carriage of similar KPC-harbouring plasmids within genetically distinct K. pneumoniae and to clonal spread of K. pneumoniae with unrelated KPC plasmids.

Identification of PER-1 extended-spectrum β-lactamase producingPseudomonas aeruginosaclinical isolates of the international clonal complex CC11 from Hungary and Serbia

PER-1 extended-spectrum beta-lactamase-producing Pseudomonas aeruginosa clinical isolates from Budapest, Hungary, and Belgrade, Serbia, were characterized by molecular methods. Two PER-1-positive isolates were recovered from sporadic cases in Budapest and a small cluster of PER-1-positive infections involving four patients were identified at a Belgrade hospital. A class 1 integron harbouring a bla(OXA-2)beta-lactamase gene and four other gene cassettes was detected in both the Budapest and the Belgrade isolates. The two P. aeruginosa isolates from Budapest also carried another class 1 integron containing bla(OXA-74), aac(6')-Ib-cr and cmlA7 genes in its variable region. The aac(6')-Ib-cr fluoroquinolone-acetylating aminoglycoside acetyltransferase gene is described here for the first time in P. aeruginosa. Multilocus sequence typing (MLST) revealed that the PER-1 positive P. aeruginosa isolates identified in this study display ST235, a sequence type that belongs to clonal complex CC11. Two bla(PER-1)-positive P. aeruginosa reference isolates from France and Belgium could also be assigned to complex CC11 by MLST. Our results underscore the role of complex CC11 in the dissemination of bla(PER-1) among P. aeruginosa clinical isolates.

Molecular epidemiology of PER-1 extended spectrum β-lactamase among gram-negative bacteria isolated at a tertiary care hospital

The bla(PER-1) presence was sought by PCR in 289 ceftazidime resistant Gram-negative bacteria isolated at Dokuz Eylul University Hospital (Turkey) between 1998 and 2003. PER-1 production rates were 32.3, 33.9, 14.9 and 37.9% in the 1998-2000 period, 2001, 2002 and 2003, respectively. bla(PER-1) was detected in 46.2 and 35.9% of ceftazidime-resistant Pseudomonas aeruginosa and Acinetobacter baumannii isolates, respectively. ERIC-PCR results revealed that dissemination of two endemic clones for both P. aeruginosa (X and Y) and A. baumannii (A and B) was responsible for the high prevalence. Results of the conjugation tests and plasmid curing experiments suggested that bla(PER-1) was located on the chromosome in the representative strains. It was also shown for the first time that bla(PER-1) in a clinical isolate was associated with class-1 integron which could facilitate dissemination of bla(PER-1) among bacteria.

Metallo-beta-lactamase-producing Enterobacteriaceae isolates in a university hospital in Taiwan: prevalence of IMP-8 in Enterobacter cloacae and first identification of VIM-2 in Citrobacter freundii.

A total of 9082 clinical isolates of Enterobacteriaceae other than Klebsiella spp. collected in 1999 and 2000 at a university hospital in Taiwan were investigated for the production of metallo- beta-lactamases (MBLs). Thirty-six (2.9%) of the 1261 Enterobacter cloacae isolates and one (0.3%) of the 340 Citrobacter freundii isolates were found to carry bla(IMP-8) and bla(VIM-2), respectively, by colony hybridization, PCR and sequence analysis. The IMP-8 producers were recovered from 20 patients and four of them had recently transferred from other hospitals, implying spread of IMP-8-producing E. cloacae among different healthcare settings. Of the 20 non-repetitive IMP-8 producers, 17 (85%) isolates also harboured bla(SHV-12), which was on the same transferable plasmids with bla(IMP-8). The bla(VIM-2)-positive isolate and all non-repetitive bla(IMP-8)-positive isolates appeared susceptible to imipenem (MICs < 8 mg/L) and meropenem (MICs < 4 mg/L), indicating the difficulty in detection of MBLs in Enterobacteriaceae by routine susceptibility testing. Ribotyping of the IMP-8-producing E. cloacae isolates indicated that the dissemination of bla(IMP-8) was due largely to the spread of an epidemic clone, but horizontal transfer among unrelated strains also occurred.