Can a new test detect Stenotrophomonas maltophilia?
Why is this important?
Several cystic fibrosis centres worldwide have reported that Stenotrophomonas maltophilia has become more common. This is a multi-drug resistant, opportunistic bacterium that often causes hospital-acquired infections (e.g. pneumonia). Although, the clinical consequences and importance of S. maltophilia colonisation in people with CF’sairways are still debated, it has been recently demonstrated that chronic S. maltophilia infection may increase the risk for pulmonary exacerbations.
What did you do?
Infection markers for S. maltophilia, such as antibodies, may be helpful in determining colonisation/infection of this bacterium in CF patients. We tested for specific S. maltophilia antibodies in the blood of these patients. We also investigated whether there was a correlation between the concentration of S. maltophilia antibody present, and different categories of colonisation (never, intermittent and chronic S. maltophilia or Pseudomonas aeruginosa infection).
What did you find?
Our results showed that patients chronically colonised by S. maltophilia exhibited higher antibody levels than patients never colonised by S. maltophilia or P. aeruginosa. We also determined a cut-off value by which our test can distinguish CF patients never colonized by S. maltophilia or P. aeruginosa, and patients chronically colonised by S. maltophilia.
What does this mean and reasons for caution?
The levels of S. maltophilia antibodies differed substantially between the three groups of CF patients: “never colonised by S. maltophilia or P. aeruginosa”, “intermittent colonisation” and “chronic colonisation”.
Our next steps will be to focus on addressing: the relevance of increased S. maltophilia antibody levels over time; the significance of the presence of S. maltophilia antibodies in childhood; and finally if antibody concentration is reduced after specific treatment for S. maltophilia.