Stenotrophomonas maltophilia responsible for respiratory infections in neonatal intensive care unit: antibiotic susceptibility and molecular typing.

ABSTRACT

OBJECTIVE: The aim of this study was to investigate the molecular epidemiology of Stenotrophomonas maltophilia strains responsible for respiratory infection in a neonatal intensive care unit (NICU) in Tunis City, isolated during 22 months (December 2003-September 2005). MATERIALS AND METHODS: Twelve strains of S. maltophilia isolated from tracheal aspirates of distinct infants and two environmental strains were tested for antibiotic susceptibility and genotyped by pulsed-field gel electrophoresis (PFGE) method. RESULTS: Unlike a large heterogeneity demonstrated by the antibiotyping method, PFGE identified two concomitant outbreaks consisting of nine, including an environmental strain (clone A), and four strains (clone B), respectively; a distinguishable strain was classified in a unique pattern (PFGE type C). The long-term dissemination of these strains is a characteristic feature of these outbreaks. Improvement of hygienic conditions attributed to a markedly decrease in their isolation frequencies. Concomitant outbreaks and long period persistence of S. maltophilia in NICU is an important finding of this study. CONCLUSION: Identification of two clonal strains of S. maltophilia responsible of respiratory infection. Epidemic strains are hardly eradicated when colonization is established.