JAC Advance Access originally published online on January 25, 2007
Journal of Antimicrobial Chemotherapy 2007 59(3):578-579; doi:10.1093/jac/dkl508
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Correspondence |
Emerging bacterial pathogens: Escherichia coli, Enterobacter aerogenes and Proteus mirabilis clinical isolates harbouring the same transferable plasmid coding for metallo-ß-lactamase VIM-1 in Greece
1 Fourth Department of Internal Medicine, Molecular Biology Section, University of Athens Medical School, Athens, Greece 2 Second Department of Internal Medicine, Sismanoglion General Hospital, Athens, Greece
* Correspondence address. Fourth Department of Internal Medicine, University General Hospital ‘ATTIKON’, Rimini 1, 124 62 Chaidari, Greece. Tel: +32105326426; Fax: +32105326446; E-mail: hgiama{at}ath.forthnet.gr
Keywords: blaVIM , carbapenemases , Enterobacteriaceae
Until now, there have been only a few reports on the production of VIM-type metallo-ß-lactamases (MBLs) in members of the family Enterobacteriaceae.1–6 We report here the isolation of Escherichia coli, Enterobacter aerogenes and Proteus mirabilis clinical isolates producing the MBL VIM-1 encoded by the same conjugative plasmid.
An E. coli clinical isolate, a P. mirabilis clinical isolate and an E. aerogenes clinical isolate with decreased susceptibility to carbapenems and a positive imipenem-EDTA double-disc synergy test (DDST) were isolated from three different patients hospitalized in different tertiary care hospitals in the Athens area. E. coli 6641 was isolated in 2002 from the urine of a patient who had been recently hospitalized for a urinary tract infection by an imipenem-susceptible P. aeruginosa strain. The patient was treated with imipenem 15 days before the isolation of E. coli 6641, which was considered a colonizer. P. mirabilis 73 was isolated in 2003 from the cerebrospinal fluid of a patient suffering from nosocomial meningitis secondary to craniocerebral trauma. The infection was successfully treated with colistin given both intravenously and intrathecally. E. aerogenes 1159 was isolated in 2004 from the blood culture of a patient suffering from acute myelogenous leukaemia. The patient while neutropenic, developed bacteraemia complicated by septic shock and was successfully treated with imipenem. She had not received any antibiotics prior to this episode.
Species identification was confirmed by the API20E system (bioMérieux, Marcy l'Étoile, France). MICs of antimicrobial agents were determined by the broth microdilution method. The MICs of carbapenems were also determined using a higher inoculum (108 cfu/mL) in order to detect an inoculum effect. Imipenem-EDTA DDST was performed for screening of MBL production.7 The transferability of the blaVIM gene was determined by the filter mating method.5 Isoelectric focusing of sonic extracts was performed on precast polyacrylamide gels with a pH 3–10 gradient and with reference ß-lactamases used as controls. PCR amplification of blaVIM, blaTEM and blaSHV as well as detection and mapping of class 1 integrons were performed using primers described elsewhere.2,4,5,8 PCR amplicons ligated to pCR2.1 vector (TA Cloning Kit; Invitrogen, Carlsbad, CA, USA) were sequenced on both strands with an ABI Prism 377 DNA sequencer (Applied Biosystems, Foster City, CA, USA). Nucleotide sequence analysis and database similarity searches were carried out at the NCBI website (http://www.ncbi.nlm.nih.gov/). Plasmid similarities were documented by RFLP analysis with EcoRI and HindIII restriction endonucleases (New England Biolabs Ltd, Hertfordshire, UK).
Susceptibility results are shown in Table 1. When a high inoculum was used, the MICs of all carbapenems rose to >512 mg/L with the exception of the MIC of ertapenem for E. coli 6641 which was 128 mg/L. Ceftazidime resistance was freely transferred to E. coli recipient RC85 from all the three donors with a frequency of 10–5. All three E. coli transconjugants demonstrated a positive imipenem-EDTA DDST and in isoelectric focusing only one nitrocefin-hydrolysing band (pI 5.5) was visualized in their extracts. Plasmid DNA isolation revealed the presence of a plasmid of at least 60 kb with the same EcoRI and HindIII RFLP analysis profile in all three transconjugants. PCR experiments yielded a 510 bp amplification product that suggested the presence of a blaVIM allele in all three clinical isolates and their transconjugants. A blaTEM-like gene was present in E. coli 6641 and P. mirabilis 73 clinical isolates, while a blaSHV-like gene was present in the E. aerogenes 1159 clinical isolate. PCR mapping indicated that the blaVIM-1 gene was part of a class 1 integron with a gene cassette array that included (from 5' to 3') blaVIM-1, dhfrI and aadA. DNA sequencing of both strands of various overlapping PCR amplicons from the three clinical isolates and the respective E. coli transconjugants showed that this class 1 integron was similar to that previously described in Acinetobacter baumannii,9 Klebsiella pneumoniae4 and an E. coli from Greece with the only difference being the absence of aacA7 in the isolates of the present study.3 The nucleotide sequences of integrons In6641, In1159 and In73 have been assigned the EMBL/GenBank accession numbers EF078697 [GenBank] , EF093145 [GenBank] and EF093146 [GenBank] .
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This is the first report of an E. aerogenes isolate carrying a blaVIM gene. This report highlights two interesting points. From a clinical point of view, there is a paucity of data on the efficacy of carbapenems against MBL-producing pathogens exhibiting reduced susceptibility to these agents. One of the patients described here was successfully treated with imipenem for primary E. aerogenes bacteraemia although the MIC of imipenem was 8 mg/L and significantly increased when a higher inoculum was used. This case report suggests that carbapenems may maintain clinical efficacy against some MBL-positive members of the family Enterobacteriaceae but clinical studies are warranted in order to determine the most appropriate antimicrobial treatment for these infections.
From an epidemiological point of view, the dissemination of a transferable plasmid coding for MBL among various species of Enterobacteriaceae of the hospital flora in Greece is a very worrisome phenomenon. The reservoir of mobile elements carrying the blaVIM-1 gene in Greek hospitals has been reported to be K. pneumoniae, until now successfully confined in the ICUs.4 Spread of these elements via transferable plasmids to other species may facilitate their propagation out of the ICUs and into the community. The extent of the problem is unknown since the presence of MBL enzymes is underestimated in Enterobacteriaceae because of significant variation of carbapenem MICs among them. There is definitely an urgent need for accurate screening methods for MBL-producing isolates and prompt institution of infection control measures to effectively prevent their spread in the hospital.
We confirm no conflicting financial interests.
References
1
Walsh TR, Toleman MA, Poirel L, et al. (2005) Metallo-ß-lactamases: the quiet before the storm? Clin Microbiol Rev 18:306–25.
2 Galani I, Souli M, Chryssouli Z, et al. (2004) First identification of an Escherichia coli clinical isolate producing both metallo-ß-lactamase VIM-2 and extended-spectrum ß-lactamase IBC-1. Clin Microbiol Infect 10:757–60.[CrossRef][Web of Science][Medline]
3
Miriagou V, Tzelepi E, Gianneli D, et al. (2003) Escherichia coli with a self-transferable, multiresistant plasmid coding for metallo-ß-lactamase VIM-1. Antimicrob Agents Chemother 47:395–7.
4
Giakkoupi P, Xanthaki A, Kanelopoulou M, et al. (2003) VIM-1 metallo-ß-lactamase-producing Klebsiella pneumoniae strains in Greek hospitals. J Clin Microbiol 41:3893–6.
5
Galani I, Souli M, Chryssouli Z, et al. (2005) Characterization of a new integron containing blaVIM-1 and aac(6')-IIc in an Enterobacter cloacae clinical isolate from Greece. J Antimicrob Chemother 55:634–8.
6 Vourli S, Tsorlini H, Katsifa H, et al. (2006) Emergence of Proteus mirabilis carrying the bla metallo-ß-lactamase gene. Clin Microbiol Infect 12:691–4.[CrossRef][Web of Science][Medline]
7 Lee K, Chong Y, Shin HB, et al. (2001) Modified Hodge and EDTA-disk synergy tests to screen metallo-ß-lactamase-producing strains of Pseudomonas and Acinetobacter species. Clin Microbiol Infect 7:88–91.[CrossRef][Web of Science][Medline]
8 Galani I, Xirouchaki E, Kanellakopoulou K, et al. (2002) Transferable plasmid mediating resistance to multiple antimicrobial agents in Klebsiella pneumoniae isolates in Greece. Clin Microbiol Infect 8:579–88.[CrossRef][Web of Science][Medline]
9 Tsakris A, Ikonomidis A, Pournaras S, et al. (2006) VIM-1 metallo-ß-lactamase in Acinetobacter baumannii. Emerg Infect Dis 12:981–3.[Web of Science][Medline]
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