Molecular epidemiology of Pseudomonas aeruginosa infections in a cystic fibrosis outpatient clinic

Instituto da Criança, Hospital das Clínicas, *Laboratory of Virology, Instituto de Medicina Tropical de São Paulo and Microbiology Section of the Central Laboratory, Hospital das Clínicas, University of São Paulo Medical School (FMUSP), São Paulo, SP, Brazil Corresponding author: Dr L.V.F. da Silva Filho (e-mail: vicres{at}usp.br ). Received 17 March 2000; revised version accepted 11 August 2000. Abstract Chronic respiratory infection by Pseudomonas aeruginosa is a significant determinant in the prognosis of cystic fibrosis patients. Cross-infection between cystic fibrosis patients and the prevalence of P. aeruginosa among them were investigated by microbiological surveillance and RAPD typing of the isolates. A total of 748 samples was cultured, including specimens from the respiratory tract (sputum or throat swabs) and hands of patients and medical staff, resulting in the collection of 86 isolates of P. aeruginosa from 65 samples. Prevalence of P. aeruginosa was 39.3% in respiratory samples, 0.2% on patients’ hands and none in the medical staff's hand samples. RAPD typing characterised 51 genotypes and clonal persistence was observed in the majority of patients. These results suggest that cross-infection is not common in the outpatient clinic studied and a common source of acquisition is unlikely.