Genetic relatedness among clinical strains of Stenotrophomonas maltophilia in tertiary care hospital settings in São Paulo State, Brazil

Relação genética entre isolados clínicos de Stenotrophomonas maltophilia em hospitais terciários do Estado de São Paulo, Brasil

Abstracts

Stenotrophomonas maltophilia is a Gram-negative bacillus, which is becoming widely recognized as an important nosocomial pathogen. The main objective of this study was to evaluate the genetic relatedness, by random amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) of 86 clinical isolates of S. maltophilia (colonization 22, infection 64) obtained from 79 hospitalized patients, from different geographic regions of São Paulo State. The genotypic analysis performed by RAPD and PFGE was used in 24 isolates for genetic identity confirmation. The results were congruent between the two methods but it was not possible to link genetic profiles with the studied variables, clinical state and geographic area, probably due to the great variability among the strains. The analyses by PFGE confirmed identity in 5 pairs of microorganisms and RAPD, in this study, showed to be a useful tool for investigation of diversity leading the identification of 85 genetic profiles. The genetic diversity shown may be due to re-infection by different strains or co-infection by multiple strains which suggests multiple entry sources of the bacterium in the hospital setting or of acquisition by patient. In this setting, colonization, infection and re-infection occur with unknown frequency, raising the need for the establishment of specific control measures.

Stenotrophomonas maltophilia; RAPD; PFGE