564 Letters to the Editor / International Journal of Antimicrobial Agents 40 (2012) 562–573 sulfonamides, tobramycin and gentamicin and was susceptible to amikacin (MIC = 1 mg/L), chloramphenicol, tetracycline and fluo- roquinolones. PCR experiments with primers designed to detect Ambler class A, B and D genes, followed by sequencing, identified the bla OXA-48 carbapenemase gene in both isolates [2]. Klebsiella pneumoniae AEL also possessed the ESBL bla CTX-M-15 gene together with bla OXA-1 and bla SHV-28 genes, whereas E. coli ZAN co-harboured the ESBL bla CTX-M-24 gene and the bla TEM-1 gene. The genetic environment of the bla OXA-48 gene was determined by PCR mapping using specific primers for the insertion sequence IS1999, located upstream and downstream of the gene in Tn1999 [2]. Tn1999 was identified in E. coli ZAN isolate whereas Tn1999.2, differing from Tn1999 by the insertion of an IS1R element, was identified in K. pneumoniae AEL. In K. pneumoniae AEL, mating- out assays and plasmid DNA analysis performed as described previously [2] allowed identification of the bla OXA-48 gene in a 62-kb conjugative plasmid similar to that of the prototype OXA- 48-positive K. pneumoniae 11978 strain from Turkey and other OXA-48-producers from other geographical origins [1]. Mating-out assays using E. coli ZAN were unsuccessful. To search for a pos- sible chromosomal location of the bla OXA-48 gene, the technique using the endonuclease I-CeuI was performed as described previ- ously [4] and confirmed the chromosomal location of the bla OXA-48 gene (data not shown). Multilocus sequence typing (MLST) performed as described pre- viously [2] showed that K. pneumoniae AEL belonged to a new sequence type ST900 (allelic profile 1-6-1-5-4-1-6). Noticeably, ST900 is a single-locus variant of ST101 (allelic profile 2-6-1-5-4-1- 6), and OXA-48-producing K. pneumoniae belonging to ST101 have been reported in Tunisia, Spain and South Africa (personal data), highlighting the wide dissemination of this sequence type [2,5]. Escherichia coli ZAN belonged to ST38, similar to other OXA-48- producing E. coli isolates reported in France from patients coming from Egypt and Turkey [1]. Interestingly, those recently identified isolates co-produced the same -lactamases as E. coli ZAN, namely TEM-1 and CTX-M-24, suggesting their clonal spread in various European countries. Although recent data suggest that the current spread of the bla OXA-48 gene is mainly linked to the transfer of a single epidemic IncL/M-type plasmid, K. pneumoniae ST101 and ST395 together with E. coli ST38 may be considered as epidemic strains and likely contribute to the spread of that resistance determinant [1]. Interest- ingly, we report here for the first time a chromosomal acquisition of the bla OXA-48 gene. This report underlines that importation of carbapenemase-producers and their potential subsequent diffu- sion may occur despite strict control of antibiotic stewardship and high quality of hand hygiene as reported in the University Hospital of Geneva (Geneva, Switzerland). Acknowledgments The authors thank platform Genotyping of Pathogens and Public Health (Institut Pasteur, Paris, France) for coding MLST alleles and profiles and making them available at http://www.pasteur.fr/mlst. Funding: This work was supported by a grant from the Min- istère de la Recherche, Université Paris XI (Paris, France) and by INSERM (France). The research leading to these results has also received funding from the European Community’s Seventh Framework Programme FP7/2007-2013 under grant agreement no. 241742 (TEMPOtest-QC) and no. 282512 (R-GNOSIS). Competing interests: None declared. Ethical approval: Not required. References [1] Poirel L, Potron A, Nordmann P. OXA-48-like carbapenemases: the phantom menace. J Antimicrob Chemother 2012;67:1597–606. [2] Potron A, Kalpoe J, Poirel L, Nordmann P. European dissemination of a single OXA-48-producing Klebsiella pneumoniae clone. Clin Microbiol Infect 2011;17: E24–6. [3] Clinical and Laboratory Standards Institute. Performance standards for antimi- crobial susceptibility testing; twenty-first informational supplement. Document M100-S21. Wayne, PA: CLSI; 2011. [4] Potron A, Poirel L, Croizé J, Chanteperdrix V, Nordmann P. Genetic and biochemical characterization of the first extended-spectrum CARB-type - lactamase, RTG-4, from Acinetobacter baumannii. Antimicrob Agents Chemother 2009;53:3010–16. [5] Lahlaoui H, Poirel L, Barguellil F, Moussa MB, Nordmann P. Carbapenem- hydrolyzing class D -lactamase OXA-48 in Klebsiella pneumoniae isolates from Tunisia. Eur J Clin Microbiol Infect Dis 2012;31:937–9. Anaïs Potron Service de Bactériologie-Virologie, INSERM U914 «Emerging Resistance to Antibiotics», Hôpital de Bicêtre, Faculté de Médecine et Université Paris-Sud, 94275 K.-Bicêtre, France Jacques Schrenzel Bacteriology Laboratory and Genomic Research Laboratory, Geneva University Hospitals, Geneva, Switzerland Laurent Poirel Service de Bactériologie-Virologie, INSERM U914 «Emerging Resistance to Antibiotics», Hôpital de Bicêtre, Faculté de Médecine et Université Paris-Sud, 94275 K.-Bicêtre, France Gesuele Renzi Abdessalam Cherkaoui Bacteriology Laboratory and Genomic Research Laboratory, Geneva University Hospitals, Geneva, Switzerland Patrice Nordmann ∗ Service de Bactériologie-Virologie, INSERM U914 «Emerging Resistance to Antibiotics», Hôpital de Bicêtre, Faculté de Médecine et Université Paris-Sud, 94275 K.-Bicêtre, France ∗ Corresponding author. Present address: Service de Bactériologie-Virologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre cedex, France. Tel.: +33 1 45 21 36 32; fax: +33 1 45 21 63 40. E-mail address: nordmann.patrice@bct.aphp.fr (P. Nordmann) 6 July 2012 doi:10.1016/j.ijantimicag.2012.07.003 Low prevalence of vancomycin heteroresistance among meticillin-resistant Staphylococcus aureus causing bacteraemia in Hong Kong Sir, Infections caused by meticillin-resistant Staphylococcus aureus (MRSA) with heterogeneous resistance to vancomycin (hVISA) are more likely to fail treatment with vancomycin, leading to persistent bacteraemia, relapse and the emergence of vancomycin- intermediate S. aureus (VISA) [1]. This study investigated 249 consecutive bacteraemia MRSA isolates recovered from inpatients treated in four healthcare districts (designated A–D) in Hong Kong in 2009. The hospitals in the healthcare districts together served approximately one-half of the 7 million population in Hong Kong. Vancomycin minimal inhibitory concentrations (MICs) were deter- mined by the broth microdilution method using an arithmetic dilution (0.094, 0.125, 0.19, 0.25, 0.38, 0.5, 0.75, 1, 1.5, 2, 3 and 4 mg/L). Quality control strains (including S. aureus ATCC 29213 and 12 in-house MRSA internal control strains with vancomycin MICs of 0.5–4 mg/L) were included on each day of testing. Antimi- crobial susceptibility testing was performed by the Clinical and Laboratory Standards Institute (CLSI) disk diffusion method [2].