Polyclonal endemicity of Pseudomonas aeruginosa in a teaching hospital from Brazil: molecular typing of decade-old strains

Fortaleza CMCB (1), Bacchi CE (2), Oliveira DE (2), Ramos MC (3)

(1) Department of Tropical Diseases and Imaging Diagnosis, Botucatu Medical School, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil; (2) Department of Pathology, Botucatu Medical School, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil; (3) School of Medical Sciences, State University of Campinas, UNICAMP, Campinas, São Paulo State, Brazil.

Abstract: Pseudomonas aeruginosa infections cause significant mortality and morbidity in health care settings. Strategies to prevent and control the emergence and spread of P. aeruginosa within hospitals involve implementation of barrier methods and antimicrobial stewardship programs. However, there is still much debate over which of these measures holds the utmost importance. Molecular strain typing may help elucidate this issue. In our study, 71 nosocomial isolates from 41 patients and 23 community-acquired isolates from 21 patients were genotyped. Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) was performed. Band patterns were compared using similarity coefficients of Dice, Jaccard and simple matching.  Strain similarity for nosocomial strains varied from 0.14 to 1.00 (Dice); 0.08 to 1.00 (Jaccard) and 0.58 to 1.00 (simple matching). Forty patterns were identified. In most units, several clones coexisted. However, there was evidence of clonal dissemination in the high risk nursery, neurology and two surgical units. Each and every community-acquired strain produced a unique distinct pattern. Results suggest that cross transmission of P. aeruginosa was an uncommon event in our hospital. This points out to a minor role for barrier methods in the control of P. aeruginosa spread.

Key words: Pseudomonas aeruginosa, strain typing, ERIC-PCR, nosocomial infections, health care infections.

ACKNOWLEDGEMENTS

We are thankful to the State of São Paulo Research Foundation (FAPESP) for the financial support.

COPYRIGHT

© CEVAP 2011

SUBMISSION STATUS

Received: November 16, 2010.

Accepted: March 16, 2011.

Abstract published online: March 17, 2011.

Full paper published online: May 31, 2011.

CONFLICTS OF INTEREST

There is no conflict.

FINANCIAL SOURCE

The State of São Paulo Research Foundation (FAPESP) provided the financial grants.

ETHICS COMMITTEE APPROVAL

The present study was approved by the Research Ethics Committee of Botucatu Medical School (protocol number 0394), UNESP, Brazil.

CORRESPONDENCE TO

CARLOS MAGNO CASTELO BRANCO FORTALEZA, Departamento de Doenças Tropicais e Diagnóstico por Imagem, Faculdade de Medicina de Botucatu, UNESP, Distrito de Rubião Junior, s/n, Botucatu, SP, 18618-970, Brazil. Phone: +55 14 3811 6212. Fax: +55 14 3815 9898. Email: cmfortaleza@uol.com.br.