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Emergence of VanB phenotype-vanA genotype in vancomycin-resistant enterococci in Brazilian hospital

Emergência de enterococos resistentes à vancomicina com fenótipo VanB e genótipo vanA em hospital brasileiro

Abstracts

In Brazil, vancomycin-resistant enterococci (VRE) have been reported as nosocomial pathogens since 1998. Recently, in a VRE surveillance in a hospital, we detected two Enterococcus faecalis isolates with vanA genotype and susceptible to teicoplanin. This is the first report of VanB phenotype-vanA genotype enterococci isolated from humans in Brazil.

enterococci; vanA genotype; VanB phenotype; vancomycin; VRE


No Brasil, enterococos resistente à vancomicina (VRE) têm sido descritos como patógenos hospitalares, desde 1998. Durante um monitoramento de VRE em um hospital, foram detectadas duas cepas de Enterococcus faecalis com genótipo vanA, e sensibilidade à teicoplanina. Este é o primeiro relato do isolamento de enterococo fenótipo VanB e genótipo vanA de amostra clínica no Brasil.

enterococos; genótipo vanA; fenótipo VanB; vancomicina; VRE


MEDICAL MICROBIOLOGY

SHORT COMMUNICATION

Emergence of VanB phenotype-vanA genotype in vancomycin-resistant enterococci in Brazilian hospital

Emergência de enterococos resistentes à vancomicina com fenótipo VanB e genótipo vanA em hospital brasileiro

Rosemeire Cobo ZanellaI,* * Corresponding Author. Mailing address: Instituto Adolfo Lutz, Laboratório de Bacteriologia, Av. Dr. Arnaldo, 355, Cerqueira César. 01246-902, São Paulo, Brasil. Fax: (+5511) 3085-3505. E-mail: cobo@ial.sp.gov.br ; Marisa de Jesus Castro LimaI; Luciana Soares TeganiI; Adriana HitomiI; Maria Cristina de Cunto BrandileoneI; Izabel Cristina V. PalazzoII; Ana Lúcia da Costa DariniII

IInstituto Adolfo Lutz, Laboratório de Bacteriologia, São Paulo, SP, Brasil

IIFaculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil

ABSTRACT

In Brazil, vancomycin-resistant enterococci (VRE) have been reported as nosocomial pathogens since 1998. Recently, in a VRE surveillance in a hospital, we detected two Enterococcus faecalis isolates with vanA genotype and susceptible to teicoplanin. This is the first report of VanB phenotype-vanA genotype enterococci isolated from humans in Brazil.

Key words: enterococci, vanA genotype, VanB phenotype, vancomycin, VRE

RESUMO

No Brasil, enterococos resistente à vancomicina (VRE) têm sido descritos como patógenos hospitalares, desde 1998. Durante um monitoramento de VRE em um hospital, foram detectadas duas cepas de Enterococcus faecalis com genótipo vanA, e sensibilidade à teicoplanina. Este é o primeiro relato do isolamento de enterococo fenótipo VanB e genótipo vanA de amostra clínica no Brasil.

Palavras-chave: enterococos, genótipo vanA, fenótipo VanB, vancomicina, VRE

Vancomycin-resistant enterococci (VRE) were first reported in 1988 in Europe, and then they have emerged and disseminated as an important cause of nosocomial infections worldwide. Glycopeptide resistance in enterococci is associated with a variety of phenotypes and genotypes. Two principal phenotypes of resistance in VRE have been described and associated to nosocomial infections. In enterococci, the vanA phenotype is characterized by high-level resistance to vancomycin and teicoplanin, whereas the VanB phenotype by vancomycin resistance and teicoplanin susceptibility. Genes encoding the vanA- and VanB-phenotype resistance are located on transposons Tn1546 and Tn1547, respectively, or in closely related transferable genetics elements (1).

In Brazil, the first vanA Enterococcus faecium was isolated from a patient in São Paulo city in 1997, and the first VRE outbreak occurred in the same hospital one year after the first isolation (9). Furthermore, VRE isolates, E. faecium and E. faecalis vanA genotype, were reported in São Paulo and in other states of Brazil (3,8). The Adolfo Lutz Institute (IAL), the public health laboratory of São Paulo State, in Brazil, performs the monitoring of the VRE isolates for hospitals by phenotypic and genotypic characterization. At the IAL, the VRE isolates are identified by conventional biochemical tests and by a multiplex PCR assay based on the specific detection of genes encoding D-alanine:D-alanine ligases (ddl) routinely used to confirm the identification of E. faecalis and E. faecium species. All isolates are initially tested by agar dilution screening method to vancomycin by CLSI recommendations (2). The MIC to vancomycin and teicoplanin are determined by broth microdilution method, according to CLSI interpretative criteria (2). The genotype is confirmed by PCR assay with specific primers for the vanA, VanB, vanC1 and vanC2-3 genes. Molecular typing of the isolates is performed by PFGE-DR II (9).

Recently, during a VRE surveillance in a hospital located in São Paulo city, we detected two E. faecalis isolates resistant to vancomycin and susceptible to teicoplanin, consistent with the VanB phenotype (ET211 and ET217). These isolates were phenotypic and genotypically identified as E. faecalis and the resistance to vancomycin and susceptibility to teicoplanin were confirmed by two methods, the broth microdilution method and the E-test (AB Biodisk, Sweden). The MICs of vancomycin for the two isolates were above 128 mg/mL, and the teicoplanin MIC were 8 mg/mL for both isolates. The vanA genotype was confirmed by PCR assay with specific primers for the vanA and VanB genes. The molecular typing of those isolates have disclosed the same PFGE pattern for both isolates. However, this molecular pattern was different when compared with those PFGE patterns identified among the VRE isolates from the same hospital.

The phenotype and genotype results of those two isolates were confirmed by the "Laboratório Especial de Bacteriologia e Epidemiologia Molecular da Faculdade de Ciências Farmacêuticas de Ribeirão Preto - University of São Paulo". A preliminary study of characterization of the vanA resistance elements of those isolates has shown a deletion on right terminal inverted repeated nucleotides in the Tn1546.

According to some reports, the VanB phenotype-vanA genotype incongruence is result of mutations in the regulatory vanS gene (4-6) or vanA (7) cluster rearrangements. In the VRE strains described in the study the loss of part of Tn1546 can be responsible for this change in the phenotype. The data emphasize the importance on the characterization and monitoring of the resistance levels to vancomycin and teicoplanin among VRE for detecting the emergence of VanB-vanA enterococci in Brazil.

ACKNOWLEDGMENTS

We are grateful to Dr. Nelson Ribeiro Filho and Eloisa Gagliardi, for sending the VRE isolates from the Hospital Paulistano, São Paulo, Brazil. This work had financial support from Brazilian Council for Science and Technology Development (CNPq-Grants 302628/2004-5 and 303348/2004-6 and FAPESP 05/50273-7).

Submitted: June 15, 2005; Approved: February 26, 2006

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  • *
    Corresponding Author. Mailing address: Instituto Adolfo Lutz, Laboratório de Bacteriologia, Av. Dr. Arnaldo, 355, Cerqueira César. 01246-902, São Paulo, Brasil. Fax: (+5511) 3085-3505. E-mail:
  • Publication Dates

    • Publication in this collection
      18 May 2006
    • Date of issue
      June 2006

    History

    • Accepted
      26 Feb 2006
    • Received
      15 June 2005
    Sociedade Brasileira de Microbiologia USP - ICB III - Dep. de Microbiologia, Sociedade Brasileira de Microbiologia, Av. Prof. Lineu Prestes, 2415, Cidade Universitária, 05508-900 São Paulo, SP - Brasil, Ramal USP 7979, Tel. / Fax: (55 11) 3813-9647 ou 3037-7095 - São Paulo - SP - Brazil
    E-mail: bjm@sbmicrobiologia.org.br