Investigation of virulence factors and genes associated with biofilm andprotease in Stenotrophomonas maltophilia isolates in Bushehr, Iran

BACKGROUND AND OBJECTIVESStenotrophomonas maltophilia is a nosocomial pathogen. The pathogenesis of S. maltophiliainfections involves several virulence factors. The ability to form biofilm is one of the importantcharacteristics of this organism. The aim of this study was to investigate the virulence factors andgenes associated with biofilm and protease in S. maltophilia isolates in Bushehr, Iran.MATERIALS AND METHODSEighty-seven S. maltophilia isolates (۶۷ clinical isolates and ۲۰ environmental isolates) wereinvestigated. The clinical isolates were collected from three hospitals and the environmental isolateswere collected from two hospitals and one dental clinic. The isolates were examined for theproduction of virulence factors including DNase, hemolysin, protease, gelatinase, lipase, lecithinase,hyaluronidase, and biofilm. To detect rmlA, rpfF, spgM, smf-۱, StmPr۱ ۸۶۸ bp, StmPr۱ ۱۶۲۱ bp, andStmPr۲ genes, PCR and sequencing was carried out.RESULTS AND DISCUSSIONAll isolates (۱۰۰%) produced DNase, hemolysin, protease, lipase, and hyaluronidase. Seventy-eight(۸۹.۷%) isolates were gelatinase producers, and ۸۵ (۹۷.۷%) isolates were lecithinase producers. Allisolates were biofilm producers: ۷۹ (۹۰.۸%) isolates produced strong biofilm, ۵ (۵.۷%) isolatesproduced moderate biofilm, and ۳ (۳.۵%) isolates produced weak biofilm. The frequency of smf-۱,rmlA, rpfF, and spgM was ۹۳.۱%, ۸۶.۲%, ۲۶.۴%, and ۵۹.۸%, respectively. The frequency of proteasegenes including StmPr۱ ۸۶۸ bp, StmPr۱ ۱۶۲۱ bp, and StmPr۲ genes was ۱۲.۶%, ۴۱.۴%, and ۱۸.۴%,respectively. The results of our study showed that the frequency of isolates producing DNase,hemolysin, protease, gelatinase, lipase, lecithinase, hyaluronidase, and biofilm is high in Bushehr. Inthis study, all the isolates that had spgM or rpfF or both genes were strong biofilm producers. Itshould be noted that the presence of isolates that lacked spgM and rpfF genes, but produced strongbiofilm, indicates that in addition to these two genes, other genes or factors may play a role in theproduction of strong biofilm. StmPr۱ ۱۶۲۱ bp had a higher frequency among all ۸۷ isolates and alsoamong clinical isolates compared to StmPr۱ ۸۶۸ bp and StmPr۲.CONCLUSIONBased on the results of this study, S. maltophilia in our region is capable of producing several factorsincluding enzymes which might play roles in pathogenicity.

کلیدواژه ها:

Stenotrophomonas maltophilia ، biofilm ، protease ، rpfF ، spgM ، rmlA