Identification of an imipenem-resistant Pseudomonas aeruginosa clone among patients in a hospital in Rio de Janeiro V.M. Kokis a , B.M. Moreira a , F.L.P.C. Pellegrino a , M.G. Silva a , J.B. Long b , C.C.R. Bastos b , K.R.N. Santos a, * a Department of Medical Microbiology, Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil b Marcı ´lio Dias Naval Hospital, Rio de Janeiro, Brazil Received 4 November 2003; accepted 22 November 2004 KEYWORDS P. aeruginosa; Imipenem resistance; Molecular typing Summary A total of 85 Pseudomonas aeruginosa isolates were obtained from October 1999 to April 2000 in a tertiary care hospital in Rio de Janeiro, Brazil. The imipenem susceptibility was evaluated by disk diffusion and agar dilution methods, and the clonal relationship among 67 isolates was examined by macrorestriction profile analysis following pulsed-field gel electrophoresis. Imipenem resistance was observed in 52 (61.2%) isolates. Imipenem-resistant P. aeruginosa isolates were separated into 10 geno- types, 73% of which belonged to genotype A. Identification of a single P. aeruginosa clone with a high rate of imipenem resistance emphasizes the need to control the transmission of this organism among patients. Q 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. Introduction Pseudomonas aeruginosa is an important pathogen that causes nosocomial infections, particularly in intensive care units (ICUs) and burns units where the use of antimicrobial agents is intense. 1,2 Infections by this organism are often difficult to treat because of their intrinsic resistance to various antimicrobial agents and the development of resistance to other drugs during chemotherapy. 3,4 Carbapenems, such as imipenem and meropenem, are effective for treating P. aeruginosa infections due to their high stability to Ambler classes A, C and D b-lactamases compared with other b-lactams. 5 However, overuse of imipenem has been associated with the isolation of P. aeruginosa strains producing class B enzymes (IMP and VIM), called metallo-b- Journal of Hospital Infection (2005) 60, 19–26 www.elsevierhealth.com/journals/jhin 0195-6701/$ - see front matter Q 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2004.11.019 * Corresponding author. Address: Laborato ´rio de Infecc ¸o ˜es Hospitalares, Departamento de Microbiologia Me ´dica, Instituto de Microbiologia, Professor Paulo de Go ´es, CCS, Bloco I, UFRJ, Cidade Universita´ria, Rio de Janeiro, Brazil. Tel.: C55 21 22604193; fax: C55 21 2560 8028. E-mail address: santoskrn@micro.ufrj.br