Molecular characterization of resistance to Rifampicin in an emerging hospital-associated Methicillin-resistant Staphylococcus aureus clone ST228, Spain

BMC Microbiology

Research Article

Miquel Pujol¹  Virginie Mick²  Rogelio Martín²  M Angeles Domínguez²  Josefina Liñares³  Fe Tubau³ 

[1] Infectious Diseases Department, Hospital Universitari de Bellvitge, University of Barcelona, IDIBELL, Barcelona, Spain;Microbiology Department, Hospital Universitari de Bellvitge, University of Barcelona, IDIBELL, Feixa Llarga s/n, 08907, Hospitalet de Llobregat, Barcelona, Spain;Microbiology Department, Hospital Universitari de Bellvitge, University of Barcelona, IDIBELL, Feixa Llarga s/n, 08907, Hospitalet de Llobregat, Barcelona, Spain;CIBERES (CIBER de Enfermedades Respiratorias), ISCIII, Madrid, Spain;

关键词: Rifampicin;    Methicillin Resistant Staphylococcus Aureus;    rpoB Gene;    SCCmec Type;    PFGE Pattern;   

DOI  :  10.1186/1471-2180-10-68

 received in 2009-08-02, accepted in 2010-03-04,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundMethicillin-resistant S. aureus (MRSA) has been endemic in Hospital Universitari de Bellvitge, Barcelona, since 1990. During the 1990-95 period the Iberian clone (ST-247; SCCmec-I) was dominant. Isolates of clonal complex 5 (ST-125; SCCmec-IV) gradually replaced the Iberian clone from 1996 to 2003. A new multiresistant MRSA phenotype showing rifampicin resistance emerged in 2004 and rapidly increased from 25% in 2004 to 45% in 2006. The aims of this study were i) the molecular characterisation of rifampicin resistant MRSA isolates, ii) the study of the rifampicin resistance expression by disk diffusion, microdilution and E-test, and iii) the analysis of the rpoB gene mutations involved in rifampicin resistance.ResultsA sample of representative 108 rifampicin-resistant MRSA isolates belonged to a single PFGE genotype, ST-228, SCCmec type I and spa type t041. Of 108 isolates, 104 (96%) had a low-level rifampicin resistance (MICs, 2 to 4 mg/L) and 4 a high-level rifampicin resistance (MICs, 128 - ≥ 256 mg/L). Disk diffusion and E-test methods failed to identify a low-level rifampicin resistance in 20 and 12 isolates, respectively. A low-level rifampicin resistance was associated with amino acid substitution 481His/Asn in the beta-subunit of RNA polymerase. Isolates with a high-level rifampicin resistance carried additional mutations in the rpoB gene.ConclusionsThe emergence of MRSA clone ST228-SCCmec I, related to the Southern Germany clone, involved a therapeutical challenge for treating serious MRSA infections. Decreased susceptibility to rifampicin in MRSA strains of ST228-SCCmecI was associated with one or two specific mutations in the rpoB gene. One fifth of isolates with low-level rifampicin-resistance were missed by the diffusion methods.

【 授权许可】

Unknown   
© Mick et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.