What is Stenotrophomonas maltophilia?

Stenotrophomonas maltophilia or (sten malt) as it is often abbreviated, is a strain of gram negative bacteria. Similar to B. cepacia in its ability to resist treatment with antibiotics, it is often found living in aquatic environments. A study in 2002 found that unlike B. Cepacia, Stenotrophomonas maltophilia doe not reduce survival for people with cystic fibrosis. Cystic fibrosis patients can become infected with Stenotrophomonas maltophilia when they come in contact with contaminated, moist environments such as:

1. Sinus flushes
2. Mouthwash
3. Nebulizers used by other CF patients
4. Other equipment used by CF patients
5. Respiratory secretions
6. Urine or catheters
7. Open sores


Healthy people are not susceptible to stenotrophomonas maltophilia. As is the case in any situation involving the hospitalization of a patient with CF, the necessary contact precautions should be used to prevent the spread of Stenotrophomonas maltophilia. Strict adherence to proper cross-infection protocol has been very effective in reducing the risk of transferring a stenotrophomonas infection between patients in a hospital setting.

Fortunately, sten. malt. is far less likely to cause infection than PA. "Several studies in the US and elsewhere have been performed to find out the effect of Steno colonization on lung function and morbidity in CF patients, and none of them found that Steno actually causes a significant effect, unlike B. cepacia, for example. It just seems to like to sit in the cf lung." (M B Avison, PhD. University of Bristol, UK. www.bris.ac.uk/bcare/BGG)

It has a very limited ability to cause infection in humans and is only potentially lethal when it infects the bloodstream causing bacteremia. Overall, infections of sten. malt. are quite rare. They can be treated using a synergistic approach of intravenous medications that are targeted to gram-negative bacteria. This may involve treatment with colymycin and tobramycin used together.

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Supporting documentation

Synergistic Activities of Macrolide Antibiotics against Pseudomonas aeruginosa, Burkholderia cepacia, Stenotrophomonas maltophilia, and Alcaligenes xylosoxidans Isolated from Patients with Cystic Fibrosis

Prevalence and antimicrobial susceptibility of microorganisms isolated from sputa of patients with cystic fibrosis.

Factors Affecting the Incidence of Stenotrophomonas maltophilia Isolation in Cystic Fibrosis^*