With the widespread use of antibiotics and dramatic improvement in patients survival, newer organisms, such as Stenotrophomonas maltophilia (Denton et al, 1996; Denton et al, 1998; Talmaciu et al, 2000; Krzewinski et al, 2001), Achromobacter xylosoxidans (Dunne & Maisch, 1995; Krzewinski et al, 2001; Tan et al, 2002) and nontuberculous mycobacteria (Tomashefski et al, 1996; Torrens et al, 1998; Olivier et al, 2003) are becoming more widespread. The reasons for their emergence are complex but may relate to the selective pressure exerted by repeated exposure to antibiotic therapy, improved laboratory isolation techniques and enhanced reporting. All may be associated with either simple colonisation or respiratory exacerbations in those persistently colonised with large numbers of these organisms.
The reported prevalence of S. maltophilia in CF Centres is typically 15-20% (Denton, 1997), although most patients appear only intermittently rather than chronically colonised. The main risk factor for acquisition appears to be the selective antibiotic pressure (Denton et al, 1996; Talmaciu et al, 2000; Marchac et al, 2004). The organism is widespread in the home and hospital environments, particularly in water sources (Denton et al, 1998). Equipment used to deliver aerosolised therapy may also be contaminated with S. maltophilia (Denton et al, 2003) and act as a source of infection. Studies have failed to show a clear clinical impact of S. maltophilia on people with CF (Goss et al, 2002; Goss et al, 2004). Therefore the need for, and optimum approach to therapy, remain uncertain. Most evidence suggests that cotrimoxazole (‘Septrin’) has the greatest efficacy against S. maltophilia (Conway et al, 2003). Although a study specifically using isolates from people with CF found high levels of resistance (San Gabriel et al, 2004), cotrimoxazole was often synergistic when used in combination with agents such as ticarcillin-clavulanate (‘Timentin’) or piperacillin-tazobactam (‘Tazocin’). Other agents with frequent in vitro activity against S. maltophilia include tetracyclines (e.g. minocycline, doxycycline), ceftazidime, colistin and tigecycline (Insa et al, 2007).
• Prevalence of S. maltophilia in CF Centres is typically 15-20%
• The organism is widespread in the home and hospital environments
• Studies have failed to show a clear clinical impact of S. maltophilia on people with CF
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