Bacterial resistance to ciprofloxacin in Greece: results from the National Electronic Surveillance System. Greek Network for the Surveillance of Antimicrobial Resistance.

According to 1997 susceptibility data from the National Electronic System for the Surveillance of Antimicrobial Resistance, Greece has high rates of ciprofloxacin resistance. For most species, the frequency of ciprofloxacin-resistant isolates (from highest to lowest, by patient setting) was as follows: intensive care unit > surgical > medical > outpatient. Most ciprofloxacin-resistant strains were multidrug resistant

Transferable class C β-lactamases in Escherichia coli strains isolated in Greek hospitals and characterization of two enzyme variants (LAT-3 and LAT-4) closely related to Citrobacter freundii AmpC β-lactamase

Among 2133 isolates of Escherichia coli obtained during 1996 from 10 Greek hospitals, 63 (3%) were resistant to cefoxitin. Typing by ERIC2-PCR indicated that the cefoxitin-resistant (FOX(r)) isolates were distinct. β-Lactamase studies and hybridization experiments showed that most strains produced β-lactamases related to the AmpC chromosomal cephalosporinase of Citrobacter freundii. The enzymes were encoded by similar non-self-transmissible plasmids. The bla genes encoding two β-lactamases (LAT-3 and LAT-4) with isoelectric points 8.9 and 9.4, respectively, were cloned and sequenced. The deduced amino acid sequences displayed a high degree of homology (> 95%) with the AmpC β-lactamase of C. freundii. The patterns of resistance to β-lactams of the FOX(r) E. coli depended on the quantity of class C enzymes and the simultaneous expression of other β-lactamases. In a few isolates a 36 kDa outer-membrane protein, presumably a porin, was not expressed at detectable quantities. These isolates were resistant to cefoxitin, and their susceptibility to the other β-lactams tested was not significantly decreased

Prevalence of a transferable shv-5 type β-lactamase in clinical isolates of klebsiella pneumoniae and escherichia coli in greece

Analysis with a double-disc synergy test (DDST) of clinical isolates of Klebsiella pneumoniae and Escherichia coli during the period October 1988-September 1989 revealed that 24% of the former and 4% of the latter, mainly isolated from urine, possessed an extended-spectrum β-lactamase. During this period no DDST was positive for isolates of other enterobacterial species. Transfer of ceftazidime resistance was demonstrated from six K. pneumoniae and two E. coli isolates resistant to third generation cephalosporins and aztreonam. Apart from one strain of K. pneumoniae, these strains harboured self-transferable multiresistance plasmids (c. 91 kb) with closely related EcoRI, HindIII, AvaII andPstI restriction patterns. These plasmids encoded an extended-spectrum β-lactamase thatconferred an unusually high level of resistance to ceftazidime and aztreonam (MIC ≥64mg/l). This enzyme had a pI of 8.2 and a substrate profile similar to that of the SHV-5 enzyme isolated initially in Chile, and later in France (CAZ-4). The remaining K. pneumoniae isolate harboured a transmissible multiresistance plasmid (c. 182 kb) that encoded the widely distributed SHV-2 enzyme. The resistance to cefoxitin that was observed in some of these strains was associated with outer membrane protein alterations. © 1990 by The British Society for Antimicrobial Chemotherapy

Characterization of pKP1433, a Novel KPC-2-encoding plasmid from Klebsiella pneumoniae sequence type 340

The nucleotide sequence of pKP1433 (55,417 bp), a blaKPC-2- carrying plasmid from Klebsiella pneumoniae sequence type 340, was determined. pKP1433 displayed extensive sequence and structural similarities with the IncN plasmids possessing the KPC- 2-encoding Tn4401b isoform. However, the replication, partitioning, and stability of pKP1433 were determined by sequences related to diverse non-IncN plasmids. Copyright © 2013, American Society for Microbiology

Imipenem resistance in Enterobacter aerogenes is associated with derepression of chromosomal cephalosporinases and impaired permeability

Enterobacter aerogenes mutants with high-level resistance to imipenem were studied. They were derived from strains characterized by stable overproduction of a class-I β-lactamase. This enzyme (pI = 8.2) exhibited high affinity toward imipenem and hydrolysed the drug slowly. Imipenem-resistant mutants lacked a major 43-kDa outer membrane protein and displayed decreased permeability to cephaloridine. Introduction of a plasmid coding for the regulatory ampD gene abolished β-lactamase production and rendered the mutants susceptible to imipenem. © 1992

Imipenem resistance in Enterobacter aerogenes is associated with derepression of chromosomal cephalosporinases and impaired permeability

Enterobacter aerogenes mutants with high-level resistance to imipenem were studied. They were derived from strains characterized by stable overproduction of a class-I β-lactamase. This enzyme (pI = 8.2) exhibited high affinity toward imipenem and hydrolysed the drug slowly. Imipenem-resistant mutants lacked a major 43-kDa outer membrane protein and displayed decreased permeability to cephaloridine. Introduction of a plasmid coding for the regulatory ampD gene abolished β-lactamase production and rendered the mutants susceptible to imipenem. © 1992

Characterization of pKP1780, a novel IncR plasmid from the emerging Klebsiella pneumoniae ST147, encoding the VIM-1 metallo-Β-lactamase

To determine the complete nucleotide sequence of the VIM-1-encoding plasmid pKP1780 from Klebsiella pneumoniae ST147 representing a distinct group of IncR replicons. The plasmid pKP1780 was from a K. pneumoniae clinical strain (KP-1780) isolated in Greece in 2009. Plasmid DNA was extracted from an Escherichia coli DH5a transformant and sequenced using the 454 Genome Sequencer GS FLX procedure on a standard fragment DNA library. Contig gaps were filled by sequencing of PCRproducedfragments. AnnotationandcomparativeanalysiswereperformedusingsoftwareavailableontheInternet. Plasmid pKP1780 (49770 bp) consisted of an IncR-related sequence (12083 bp) including replication and stability systems, and a multidrug resistance (MDR) mosaic region (37687 bp). blaVIM-1 along with the aacA7, dfrA1 and aadA1 cassettes comprised the variable region of an integron similar to In-e541 from pNL194. The mosaic structure also included the strA, strB, aphA1 andmphA resistance genes aswell as intact (n=10) ordefective (n=3) insertion sequences and fragments of various transposons. Themosaic structure of pKP1780 exhibited high similaritywith the acquired region of the IncN plasmid pNL194, indicating the acquisition of the VIM-1-encoding MDR region frompNL194 by an IncR-type plasmid. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved

Reduced susceptibility to vancomycin of nosocomial isolates of methicillin-resistant Staphylococcus aureus

The MICs of vancomycin for 56 random nosocomial Staphylococcus aureus isolates homogeneously resistant to methicillin (homMRSA), 16 heterogeneously resistant isolates (hetMRSA) and 25 susceptible isolates (MSSA) were determined by a standard broth microdilution method. Representative isolates were also tested by an agar incorporation method, the Etest and population analysis. Although always in the susceptible range, MICs of vancomycin for homMRSA were significantly higher than those for hetMRSA or MSSA. Moreover, a homMRSA strain belonging to one of the major Greek MRSA clones contained a sub-population of cells that could grow in the presence of vancomycin 8 mg/L at a frequency of 6.7 x 10-8

Prevalence of a plasmid-mediated type II dihydrofolate reductase gene among trimethoprim-resistant urinary pathogens in greek hospitals

The genetic basis of trimethoprim resistance was examined in 24 Klebsiella pneumoniae, 27 Enterobacter cloacae, five Enterobacter aerogenes and nine Serratia marcescens urinary isolates from five hospitals in Greece. Analysis of the 65 isolates by serotyping and phage-typing identified 53 distinct strains. Thirty-eight isolates (15 K. pneumoniae, 19 E. cloacae, two E. aerogenes and two S. marcescens) hybridized with a probe specific for a gene encoding type II dihydrofolate reductase (DHFR). Three of the K. pneumoniae and four of the E. cloacae isolates which reacted with this probe also hybridized with probes specific for type I DHFR and transposon Tn7. Two E. cloacae isolates hybridized only with the probe for type I DHFR, while a further three isolates hybridized only with the type I DHFR and Tn7 probes. None of the isolates hybridized with a probe for type V DHFR. The plasmids in transconjugants derived from 40 isolates were analysed by digestion with restriction enzymes and Southern blotting. Eighteen (45%) of the donors (12 K. pneumoniae and 6 E. cloacae) produced transconjugants containing plasmids of about 95 kb in size, while transconjugants from the other donors had plasmids in the range 100-185 kb. Of the 18 transconjugants containing a 95 kb plasmid, 15 had similar restriction endonuclease digest patterns, although they varied in terms of the range of antimicrobial resistances which they encoded. When EcoRI digests of these 15 plasmids were hybridized with the type II DHFR probe, a 23 kb common band reacted with the probe. These findings indicate that the high level of trimethoprim resistance in these genera resulted, in part, from the spread of related plasmids encoding production of type II DHFR. © 1992 by The British Society for Antimicrobial Chemotherapy