Pseudomonas aeruginosa clonal dissemination in Brazilian intensive care units.

OBJECTIVE Investigate clonal dissemination of nosocomial multidrug-resistant Pseudomonas aeruginosa isolates within and between Brazilian intensive care units, which participated in the MYSTIC Program Brazil 2002. METHODS Thirty-six P. aeruginosa isolates resistant to meropenem or imipenem plus at least two of the following drugs: ciprofloxacin, cefepime, ceftazidime or piperacillin/tazobactam were isolated during 2002 at 4 centres in São Paulo and 1 centre in Brasília. Chromosomal restriction fragments obtained with SpeI were separated by pulsed-field gel electrophoresis (PFGE). Electrophoretic patterns were analyzed with GelCompar II v. 2.5. RESULTS Five major clones were identified (A, B, C, D, G). Clone A was constituted by 8 isolates with indistinguishable PFGE pattern present in 2 centres. Clone B was constituted by 4 indistinguishable isolates predominant in centre 6. Clone C had 3 indistinguishable isolates, with closely related clones (C1-3). Also, Clone D had 3 indistinguishable isolates, with closely related (D1) and possibly related (D2/D3) clones. Clones C and D were present in centre 1. Clone G was constituted by 2 indistinguishable isolates and was present in centre 7. Finally, 8 isolates were unique. Isolates from Centre 4 were unique. CONCLUSIONS Clonal dissemination was detected within (clones A, B, C, D, and G) and between centres (clone A). These findings are important when analyzing surveillance data, since susceptibility rates may be significantly affected by the dissemination of a resistant clone.