Comparative in vitro killing of carbapenems and aztreonam against Klebsiella pneumoniae producing VIM-1 metallo-beta-lactamase.
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Anti-Bacterial Agents↗
Biomedical subjects
L S Tzouvelekis
Publications and source records attributed to L S Tzouvelekis.
Sources of diversity of carbapenem resistance levels in Klebsiella pneumoniae carrying blaVIM-1.
OBJECTIVES: To elucidate the mechanisms responsible for the diversity of beta-lactam resistance phenotypes among isolates of a VIM-1-producing Klebsiella pneumoniae (VPKP) strain that is endemic in Greek hospitals. METHODS: Five VPKP clinical isolates were studied. MICs of beta-lactams were determined by agar dilution. PFGE of XbaI-digested genomic DNA was used for typing. Profiles of outer membrane proteins (OMPs) were determined by SDS-PAGE. Selected isolates were transformed with a plasmid encoding the Omp36K porin. beta-Lactamase activities were analysed by IEF and imipenem hydrolysis was assessed by spectrophotometry. VIM-1-encoding, self-transmissible plasmids were characterized by replicon typing, RFLP and hybridization with bla(VIM)- and IS26-specific probes. Characterization of integrons was performed by PCR, cloning and sequencing. RESULTS: Isolates exhibited highly similar PFGE patterns. Imipenem MICs were 2, 4, 16, 32 and 64 mg/L. The isolate with the highest imipenem MIC (Vipm-64) lacked a 36 kDa OMP. Expression of a cloned OmpK36 in this isolate reduced the imipenem MIC to susceptibility levels. Imipenem-hydrolysing activity was significantly higher in Vipm-16 as compared with the other isolates that expressed similar amounts of VIM-1. All isolates transferred beta-lactam resistance to Escherichia coli through conjugative, IncN plasmids that exhibited differences in the RFLP and hybridization patterns with bla(VIM)- and IS26-specific probes. The Vipm-16 plasmid, mediating the higher imipenem MICs among transconjugants, carried two copies of bla(VIM-1). Cloning and sequencing showed In-e541-like integrons truncated at the 5'CS by insertion of IS26 elements at two different positions. CONCLUSIONS: A VIM-1-producing strain of K. pneumoniae has evolved through OMP alterations and rearrangements in the bla(VIM-1)-carrying plasmid probably mediated by IS26, generating isolates with imipenem MICs ranging from susceptibility to resistance.
Anti-Bacterial Agents↗
Serotypes and antimicrobial susceptibilities of 1033 pneumococci isolated from children in Greece during 2001-2004.
Pneumococci (n = 1033) isolated in the major paediatric hospitals of Athens during 2001-2004 from children with invasive infections (n = 186), non-invasive infections (n = 641) and healthy carriers (n = 206) were studied. The most prevalent serotypes were serotypes 14 (44.6%), 19F (43.5%) and 6B (22.8%) in invasive, non-invasive and carriage isolates, respectively. Among invasive isolates, the potential coverage by the seven-valent conjugate vaccine was 75.3%. Resistance rates to penicillin, amoxycillin, cefotaxime, erythromycin, co-trimoxazole, clindamycin, tetracycline and chloramphenicol were 44.6%, 2.7%, 1.2%, 43.6%, 43.5%, 12.4%, 34.7% and 5.9%, respectively. The M-phenotype accounted for 68.0% of the erythromycin-resistant isolates. All isolates were susceptible to ofloxacin.
Adolescent↗
Emergence of Proteus mirabilis carrying the bla metallo-beta-lactamase gene.
Seven genetically related Proteus mirabilis clinical isolates from a hospital in Thessaloniki, Greece, exhibited decreased susceptibility to imipenem and carried a bla(VIM-1) metallo-beta-lactamase gene. PCR mapping revealed that bla(VIM-1) was part of a class 1 integron that was probably located in the chromosome and also included the aacA7, dhfr and aadA genes. This is the first description of the bla(VIM-1) metallo-beta-lactamase gene in P. mirabilis.
Anti-Bacterial Agents↗
Transferable DHA-1 cephalosporinase in Escherichia coli.
Three Escherichia coli isolates resistant to third-generation cephalosporins but negative for extended-spectrum beta-lactamase production were isolated from hospitalised patients in Zagreb, Croatia, during June 2003 to February 2004. Resistance was due to the inducible production of a DHA-1 cephalosporinase. Each isolate contained an integron-associated bla(DHA-1)-ampR sequence carried by similar-sized plasmids, of which one was self-transferable. Serotyping and polymerase chain reaction typing using ERIC2 primer indicated that the isolates were distinct. This is the first description of DHA beta-lactamase production in E. coli.
Bacterial Proteins↗
Panresistance in VIM-1-producing Klebsiella pneumoniae.
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Anti-Bacterial Agents↗
Emergence of CTX-M-15-producing enterobacteria in Cameroon and characterization of a blaCTX-M-15-carrying element.
CTX-M-15-producing Klebsiella pneumoniae and Escherichia coli emerged recently in Cameroon. CTX-M-15 was encoded by two different multiresistance plasmids, of which one carried an ISEcp1-bla(CTX-M-15) element flanked by a 5-bp target site duplication and inserted within a Tn2-derived sequence. A truncated form of this element in the second plasmid was identified.
Anti-Bacterial Agents↗
Discrepancies and interpretation problems in susceptibility testing of VIM-1-producing Klebsiella pneumoniae isolates.
Susceptibilities to beta-lactam antibiotics of five VIM-1-producing Klebsiella pneumoniae isolates were determined by broth microdilution, Etest, disk diffusion, and the automated systems Vitek 2, Phoenix, and MicroScan. Significant discrepancies were observed in the determination of susceptibility to imipenem and meropenem. Interpretation problems by the automated systems were also noted.
Anti-Bacterial Agents↗
Repeated occurrence of diverse extended-spectrum beta-lactamases in minor serotypes of food-borne Salmonella enterica subsp. enterica.
Screening of Greek nontyphoid salmonellae from 2000 to 2002 yielded three extended-spectrum beta-lactamase (ESBL)-producing human isolates. Salmonella enterica serotype Brandenburg harbored a multiresistant SHV-5 gene-carrying plasmid. S. enterica serotype Blockley and S. enterica serotype Hadar harbored a TEM-52 gene-carrying plasmid. An S. enterica serotype Virchow strain producing plasmid-mediated CTX-M-32 was isolated twice from poultry end products. All ESBL plasmids were self-transferable and carried by clones currently common in Greece.
Aged↗
Expanded-spectrum cephalosporin resistance in non-typhoid Salmonella.
Expanded-spectrum cephalosporins (ESCs) such as ceftriaxone, together with fluorinated quinolones, are the choice antibiotics in the treatment of invasive salmonella infections. Resistance to ESCs among non-typhoid salmonella has been recognised since the late 1980s. Currently, ESC-resistant salmonella strains are reported world-wide and in some areas their incidence is significant. Resistance is mainly due to acquisition of multi-resistant plasmids encoding a variety of extended-spectrum and AmpC-type beta-lactamases. The origins of ESC-resistant salmonellae are diverse. Exchange of resistance determinants between salmonellae and nosocomial enterobacteria seems to be frequent, at least in developing countries. Also, the use of newer beta-lactams in animal husbandry and veterinary medicine may have facilitated the spread of ESC-resistant salmonella strains in livestock.
Bacterial Proteins↗
Quinolone resistance among Escherichia coli strains from community-acquired urinary tract infections in Greece.
Susceptibility data for 10 049 Escherichia coli isolates derived from community-acquired urinary tract infections in Greece during the period January 2000 to June 2002 indicated 8.1% resistance to nalidixic acid and 36% resistance to ciprofloxacin. In a sample of 170 E. coli isolates, mutations in gyrA (25 isolates) and parC (15 isolates) were consistent with the levels of resistance to quinolones. Previous exposure to quinolones and underlying chronic disease were independent risk factors for infection by quinolone-resistant E. coli strains.
Anti-Infective Agents↗
CMY-13, a novel inducible cephalosporinase encoded by an Escherichia coli plasmid.
An IncN plasmid (p541) from Escherichia coli carried a Citrobacter freundii-derived sequence of 4,252 bp which included an ampC-ampR region and was bound by two directly repeated IS26 elements. ampC encoded a novel cephalosporinase (CMY-13) with activity similar to that of CMY-2. AmpR was likely functional as indicated in induction experiments.
Cephalosporinase↗
Characterization of In111, a class 1 integron that carries the extended-spectrum beta-lactamase gene blaIBC-1.
A class 1 integron, In111, carried by a self-transferable plasmid from an Escherichia coli clinical strain was characterized. The variable region of In111 constituted an array of gene cassettes encoding the extended-spectrum beta-lactamase IBC-1, the aminoglycoside-modifying enzymes AAC(6')-Ib and ANT(3")-Ia, dihydrofolate reductase I and a putative polypeptide (SMR-2) sharing similarity with the Qac transporters. Transcription of the gene cassettes was driven by a hybrid-type P1 promoter located in a typical 5' conserved segment (CS). The 3'CS included sulI, qacEDelta1, orf5 and orf6. In111 was bounded on the right by an inversely oriented IRt. The 5'CS was preceded by an intact IS26 element followed by an aphA1 gene.
Base Sequence↗
Hospital outbreak of multiple clones of Pseudomonas aeruginosa carrying the unrelated metallo-beta-lactamase gene variants blaVIM-2 and blaVIM-4.
OBJECTIVES: The possible contribution of metallo-beta-lactamases in the frequent detection of carbapenem-resistant Pseudomonas aeruginosa isolates in a tertiary Greek hospital in Central Greece was investigated. MATERIALS AND METHODS: All carbapenem-resistant (imipenem- and/or meropenem-resistant) P. aeruginosa isolates recovered from separate patients during a 1 year period in the Clinical Microbiology Laboratory at the University Hospital of Thessaly, Larissa, Greece, were studied for metallo-beta-lactamases. They were tested by Etest MBL, PCR analysis and nucleotide sequencing. DNA fingerprints were obtained by pulsed-field gel electrophoresis (PFGE) of XbaI-digested chromosomal DNA. RESULTS: A blaVIM gene was detected in 47 of the 53 (88.7%) carbapenem-resistant P. aeruginosa isolates. PFGE grouped the blaVIM-positive isolates in six unrelated genotypes; one type included two subtypes. Nucleotide sequencing of the PCR amplicons of a randomly selected isolate from each one of the seven subtypes, detected the variant sequences blaVIM-2 in four and blaVIM-4 in three cases, respectively. They were carried as single gene cassettes or along with an aminoglycoside resistance gene (aacA29a) in class 1 integrons. CONCLUSIONS: These findings suggest that different strains of P. aeruginosa carrying unrelated metallo-beta-lactamase gene variants predominate in our hospital environment.
Anti-Bacterial Agents↗
Extended-spectrum beta-lactamase types in Klebsiella pneumoniae and Escherichia coli in two Greek hospitals.
Seventy-nine Klebsiella pneumoniae and 124 Escherichia coli clinical strains, isolated consecutively during August-October 2001 in two Greek hospitals, were examined for production of extended-spectrum beta-lactamases (ESBLs). Seventy-one (35%) isolates (46 K. pneumoniae and 25 E. coli) were ESBL-positive by phenotypic methods. Isoelectric focusing of beta-lactamases and PCR assays for bla genes showed that SHV-5-type ESBLs were the most frequent (45 isolates, 22%) followed by CTX-M (24 isolates, 12%) and IBC (three isolates, 1.5%). The latter two ESBL types may have been established recently in this setting.
Base Sequence↗
Characterization of Klebsiella pneumoniae clinical strains producing a rare extended-spectrum beta-lactamase (IBC-1).
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Anti-Bacterial Agents↗
Resistance to beta-lactams among blood isolates of Salmonella spp. in European hospitals: results from the SENTRY Antimicrobial Surveillance Program 1997-98.
The susceptibility to beta-lactams and the beta-lactamase content of 110 Salmonella spp. blood isolates collected during 1997-98 in 19 European centers participating in the SENTRY Surveillance Program were studied. Thirty-one isolates (28%) were resistant to penicillins, due to production of TEM-1 (27 isolates), OXA-1 (three isolates) or TEM-1 + OXA-1 (one isolate). All OXA-1 producers and 10 TEM-1-producing isolates were also resistant to penicillin-clavulanic acid combinations. In the latter isolates, this phenotype was associated with increased production of TEM-1. Sixteen TEM-1-producing Salmonella Enteritidis isolates and one OXA-1-producing S. Typhimurium isolate were able to transfer beta-lactam resistance by conjugation.
Anti-Bacterial Agents↗
Spread of integron-associated VIM-type metallo-beta-lactamase genes among imipenem-nonsusceptible Pseudomonas aeruginosa strains in Greek hospitals.
Fifty-eight imipenem-nonsusceptible (MIC >or= 8 microg/ml) Pseudomonas aeruginosa strains isolated during May 2001 in 15 Greek hospitals were studied. Thirty-six isolates derived from nine hospitals carried VIM-type metallo-beta-lactamase genes, as found by PCR. In 34 isolates, bla(VIM) was associated with class 1 integrons of various sizes. DNA sequencing indicated the presence of bla(VIM-2) gene cassettes in a variety of integron structures. Random amplified polymorphic DNA typing suggested diversity of the bla(VIM)-positive strains. Synergy between 2-mercaptoacetic acid and imipenem indicated carbapenemase activity in 26 bla(VIM)-positive strains.
DNA, Bacterial↗