Stenotrophomonas maltophilia: An emerging problem in cystic fibrosis patients

The prevalence of Stenotrophomonas maltophilia in cystic fibrosis patients has increased since the early 1980s, reaching 30% in some centres. The reasons for this are uncertain but may be related to increased reporting, better culture techniques, and the selective pressure of anti-pseudomonal antibiotics. There is no evidence of epidemic spread within units. Although descriptions have been given of putative virulence factors - such as extracellular enzyme production and the existence of mucoid phenotypes - their role in vivo is unknown. The clinical significance of S. maltophilia colonization is disputed but evidence is emerging of a gradual deterioration in lung function in those patients persistently colonized with bacterial counts of >10(5) cfu ml(-1) over several years. Treatment is limited by widespread resistance to many antibiotics, but susceptibility data suggest that cotrimoxazole may be useful.