First identification of an Escherichia coli clinical isolate producing both metalloβ-lactamase VIM-2 and extended-spectrum β-lactamase IBC-1

AbstractAn Escherichia coli strain with decreased susceptibility to carbapenems was isolated from a hospitalised patient in Athens, Greece. The strain was resistant to all β-lactams, including aztreonam, whereas the MIC of imipenem and meropenem was 0.5 mg/L. A positive EDTA-disk synergy test suggested the production of a metallo-β-lactamase. PCR experiments revealed the presence of the blaVIM-2, blaIBC-1 and blaTEM-1 genes. Resistance to β-lactams was not transferable by conjugation. This is the first report of a clinical isolate of E. coli producing VIM-2, and the first report of the coexistence of blaVIM-2 and blaIBC-1 in a single clinical isolate

Penetration of moxifloxacin into the human aqueous humour after oral administration

Aims: To determine the pharmacokinetics of moxifloxacin, a new generation fluoroquinolone, in the anterior chamber of the human uninflamed eye. Methods: 35 patients undergoing cataract surgery received two doses of 400 mg of oral moxifloxacin with a 12 hour interval and were divided into six groups. Moxifloxacin levels in aqueous humour and serum were determined by a microbiological agar well diffusion technique at 2, 4, 6, 8, 10, and 12 hours after the second dose in each group respectively. Results: Mean moxifloxacin levels in the anterior chamber were 1.20 (SD 0.35) μg/ml at the 2 hours group, 1.22 (0.48) μg/ml at the 4 hours group, 1.20 (0.45) μg/ml at the 6 hours group, 1.58 (0.38) μg/ml at the 8 hours group, 1.37 (0.44) μg/ml at the 10 hours group, and 1.23 (0.55) μg/ml at the 12 hours group. The mean ratio of aqueous to serum moxifloxacin level was 38%. Conclusion: Moxifloxacin penetrates well into the anterior chamber of the human uninflamed eye after oral administration, reaching early significant levels, which are maintained for at least 12 hours and are much higher than the MIC(90) values of Gram positive and Gram negative pathogens commonly implicated in intraocular infections with the exceptions of fluoroquinolone resistant staphylococci, MRSA, and Pseudomonas aeruginosa

First identification of an Escherichia coli clinical isolate producing both metallo-beta-lactamase VIM-2 and extended-spectrum beta-lactamase IBC-1

An Escherichia coli strain with decreased susceptibility to carbapenems was isolated from a hospitalised patient in Athens, Greece. The strain was resistant to all beta-lactarns, including aztreonam, whereas the MIC of imipenem and meropenem was 0.5 mg/L. A positive EDTA-disk synergy test suggested the production of a metallo-beta-lactamase. PCR experiments revealed the presence of the bla(VIM-2), bla(IBC-1) and bla(TEM-1) genes. Resistance to beta-lactams was not transferable by conjugation. This is the first report of a clinical isolate of E. coli producing VIM-2, and the first report of the coexistence of bla(VIM-2) and bla(IBC-1) in a single clinical isolate

Characterization of a new integron containing blaVIM-1 and aac(6′)-IIc in a Enterobacter cloacae clinical isolate from Greece

Objectives: A clinical isolate of Enterobacter cloacae exhibiting reduced susceptibility to imipenem and a positive EDTA-disc synergy test was studied for carbapenemase production. Materials and methods: MICs were determined with standard procedures as well as using a higher inoculum. Isoelectric focusing of cell extracts was used for detection of β-lactamases. PCR assays with primers specific for the blaVIM gene and the conserved segments of class 1 integrons and sequence analyses were carried out to identify the gene and to map the metallo-β-lactamase encoding integron. Transferability of the gene was assessed with conjugation experiments using the filter mating technique. To identify the location of the blaVIM-1 gene, Southern hybridization was carried out in genomic DNA using an internal fragment of the blaVIM-1 gene as a probe, amplified by PCR. Results: The isolate was resistant to extended-spectrum β-lactams. The MICs of carbapenems were below the resistance breakpoints but rose above resistance breakpoints when an inoculum of 108 cfu/mL was used. Isoelectric focusing detected a β-lactamase with a pl of 6.1, which exhibited imipenem-hydrolysing activity in a microbiological assay. Ceftazidime and imipenem resistance were not transferable by conjugation. PCR assays identified the blaVIM-1 gene in the variable region of a class 1 integron which also carried the aac(6′)-IIc gene. The blaVIM-1 probe hybridized with an approximately 130 kb fragment of genomic DNA, suggesting a chromosomal location of the gene. Conclusion: We describe a novel class 1 integron containing blaVIM-1 and aac(6′)-IIc genes in an E. cloacae clinical isolate. © The Author 2005. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved

Presence of plasmid-mediated quinolone resistance in Klebsiella pneumoniae and Escherichia coli isolates possessing bla(VIM-1) in Greece

Amongst nalidixic acid-resistant, ciprofloxacin-susceptible Escherichia coli and Klebsiella pneumoniae clinical isolates recovered over a 5-month period from inpatients and outpatients of Attikon University General Hospital (Athens, Greece), only one E. coli was positive for qnrB2 and one K. pneumoniae was positive for qnrA1. Both isolates were extended-spectrum beta-lactamase-negative, metallo-beta-lactamase-positive and carried the bla(VIM-1) gene. Neither of the isolates had mutations in gyrA and parC or carried aac(6’)-Ib-cr or qepA. The K. pneumoniae isolate also harboured bla(CMY-13) on the same transferable plasmid with qnrA1. This is the first report of a qnrA1-positive K. pneumoniae and qnrB2-positive E. coli harbouring a concurrent bla(VIM-1) gene. (C) 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved

Sitafloxacin (DU-6859a) and trovafloxacin: Postantibiotic effect and in vitro interactions with rifampin on methicillin-resistant Staphylococcus aureus

Sitafloxacin (DU-6859a) and trovafloxacin are novel quinolones potent on methicillin-resistant Staphylococcus aureus (MRSA) that are designed far once daily administration. In order to define the adequacy of the above regimen for the therapy of infections by multiple drug-resistant MRSA, their postantibiotic effect (PAE), their bactericidal activity, and their interactions with rifampin were determined on 14 MRSA isolates resistant to both ciprofloxacin and rifampin. PAE was defined after 1-h exposure to 1x, 4x, and 10x MIC and the killing effect offer exposure to 1x and 4x MIC. Rifampin was applied for interactive studies at a concentration of 2 mu g/mL, which is equal to its mean serum level. Median PAEs produced by 1x, 4x, and 10x MIC of sitafloxacin were 1.39, 3.75, and 6.61 h respectively, and by 1x, 4x, and 10x MIC of trovafloxacin 0.87, 2.07, and 2.23 h respectively. PAEs achieved by sitafloxacin were statistically shown to be longer than those achieved by trovafloxacin; PAEs achieved by a concentration of 10x MIC of each quinolone did not differ significantly from those achieved by a concentration of 4x MIC. Both the 4x and 10x MIC concentrations produced a more prolonged PAE than the 1x MIC concentration. A rapid bactericidal activity was expressed over the first 6 h of growth by each quinolone involving 80% of isolates enhanced in some isolates by their interaction with rifampin. The above findings revealed an extended PAE and a rapid killing effect of both sitafloxacin and trovafloxacin on MRSA resistant to ciprofloxacin and to rifampin, thus supporting their once daily administration in the therapy of infections by multiple drug-resistant MRSA. However little in vitro benefit is derived by their interaction with rifampin. (C) 1999 Elsevier Science Inc

Penetration of moxifloxacin into the human aqueous humour after oral administration

Aims: To determine the pharmacokinetics of moxifloxacin, a new generation fluoroquinolone, in the anterior chamber of the human uninflamed eye. Methods: 35 patients undergoing cataract surgery received two doses of 400 mg of oral moxifloxacin with a 12 hour interval and were divided into six groups. Moxifloxacin levels in aqueous humour and serum were determined by a microbiological agar well diffusion technique at 2, 4, 6, 8, 10, and 12 hours after the second dose in each group respectively. Results: Mean moxifloxacin levels in the anterior chamber were 1.20 (SD 0.35) mg/ml at the 2 hours group, 1.22 (0.48) mg/ml at the 4 hours group, 1.20 (0.45) mg/ml at the 6 hours group, 1.58 (0.38) mg/ml at the 8 hours group, 1.37 (0.44) mg/ml at the 10 hours group, and 1.23 (0.55) mg/ml at the 12 hours group. The mean ratio of aqueous to serum moxifloxacin level was 38%. Conclusion: Moxifloxacin penetrates well into the anterior chamber of the human uninflamed eye after oral administration, reaching early significant levels, which are maintained for at least 12 hours and are much higher than the MIC90 values of Gram positive and Gram negative pathogens commonly implicated in intraocular infections with the exceptions of fluoroquinolone resistant staphylococci, MRSA, and Pseudomonas aeruginosa

In-vitro activity and killing effect of quinupristin/dalfopristin (RP59500) on nosocomial Staphylococcus aureus and interactions with rifampicin and ciprofloxacin against methicillin-resistant isolates

Quinupristin/dalfopristin (RP59500) is a novel streptogramin and a semisynthetic derivative of pristinamycins I-A and IIB. The following properties of RP59500 were investigated: (i) its in-vitro activity against 164 hospital isolates of Staphylococcus aureus, 101 of which were methicillin-resistant (MRSA); (ii) its killing effect against 24 MRSA and seven methicillin-susceptible (MSSA) isolates; (iii) its interactions with rifampicin and ciprofloxacin against 18 MRSA isolates, six susceptible to both rifampicin and ciprofloxacin and 12 resistant to both, at 1 x MIG, 2 x MIC and 4 x MIG. Rifampicin and ciprofloxacin were applied at a concentration equal to their mean serum levels in order to establish the clinical relevance of the results. The MIG,,, MIC90, MBC50 and MBC90 of quinupristin/dalfopristin were, respectively, less than or equal to 0.015, 2, 0.12 and 2 mg/L for MRSA isolates and less than or equal to 0.015, 0.06, less than or equal to 0.015 and 0.25 mg/L for MSSA isolates. All isolates were inhibited by quinupristin/dalfopristin. Its killing effect varied with concentration and time, being optimal at 4 x MIC and after 24 h growth. Strains surviving 24 h exposure to this agent had much higher MICs than the parent strain, but only a limited number of them became resistant. Quinupristin/dalfopristin at 2 x MIC and 4 x MIC showed in-vitro synergy with rifampicin against highly resistant isolates mainly at 6 h and 24 h of growth involving 50-83% of MRSA isolates, and showed synergy with ciprofloxacin at 24 h involving 42-75% of isolates. The MIC increase in colonies surviving at 24 h was restricted by the presence of rifampicin or ciprofloxacin. In contrast, the above combinations acted synergically over the total number of MRSA strains susceptible to both rifampicin and ciprofloxacin. The above findings show that quinupristin/dalfopristin is a very potent antistaphylococcal agent, and that its activity against MRSA isolates is enhanced when it is combined with rifampicin or ciprofloxacin

Characterisation of macrolide-non-susceptible Streptococcus pneumoniae colonising children attending day-care centres in Athens, Greece during 2000 and 2003

Nasopharyngeal Streptococcus pneumoniae isolates colonising young children are representative of isolates causing clinical disease. This study determined the frequency of macrolide-non-susceptible pneumococci, as well as their phenotypic and genotypic characteristics, among pneumococci collected during two cross-sectional surveillance studies of the nasopharynx of 2847 children attending day-care centres in the Athens metropolitan area during 2000 and 2003. In total, 227 macrolide-non-susceptible pneumococcal isolates were studied. Increases in macrolide non-susceptibility, from 23% to 30.3% (p < 0.05), and in macrolide and penicillin co-resistance, from 3.4% to 48.6% (p < 0.001), were identified during the study period. The M resistance phenotype, associated with the presence of the mef(A)/(E) gene, predominated in both surveys, and isolates carrying both mef(A)/(E) and erm(AM) were identified, for the first time in Greece, among the isolates from the 2003 survey. Pulsed-field gel electrophoresis analysis of the isolates from the 2000 survey indicated the spread of a macrolide- and penicillin-resistant clone among day-care centres. The serogroups identified most commonly in the study were 19F, 6A, 6B, 14 and 23F, suggesting that the theoretical protection of the seven-valent conjugate vaccine against macrolide-non-susceptible isolates was c. 85% during both study periods