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TSM (triomethoprim/sulfamethoxazole) resistant Staphylococcus

Does a CF patient's resistant staphylococcus pose a hazard of contagion to a patient with another lung pathology?
I guess you speak about Staphylococcus aureus. Resistance to the antibiotic you mentioned (international name: cotrimoxazole or trimethoprim-sulfamethoxazole) is extremely rare except a so-called dwarf form of the microbe that doesn’t pose a risk of contagion because it remains localized within the infected cells.
The kind of Staphylococcus aureus that causes the most antibiotic resistance problems is the Meticillin-resistant Staphylococcus Aureus - MRSA (you do not specify if the staph of the concerned patient is sensible or resistant to this antibiotic).
Anyway, the problems of antibiotic resistance are more therapeutic than contagious problems. Indeed, apart from a few exceptions, there is no proven link between a microbe antibiotic resistance and its power of contagion: ie a resistant strain is not necessarily more contagious than a sensitive one. Exceptions are strains responsible for epidemic outbreaks due to the presence of substances on their membranes such as adhesins that facilitate their dissemination. This is apparently not the case of the patient you mentioned.
Just a reminder, Staphylococcus aureus is a " commensal " bacterium, say a "normal" human inhabitant. A third of the population is carrier of this bacterium in the nose and resistant forms of Staphylococcus (MRSA) can also be found in "healthy" subjects.
Outside hospital, protecting a patient with pulmonary disease from Staphylococcus would involve screening and, if necessary, decontamination of all the people he would be likely to encounter! As a result:
• In the usual practice, there is to date no recommendation for isolation of a Staphylococcus colonized CF patient from his/her entourage, even from those who have lung disease.
• Theoretically, the only exception would be the situation of a CF person with severe clinical manifestations (type necrotizing pneumonia, toxic shock syndrome, Ritter syndrome also called " scalded child") that could be due to harmful toxin producing epidemic strains. Actually, this situation would require hospitalization with all appropriate isolation measures. Fortunately, these strains circulate very little in the CF population and this is not the case of the person you are talking.
Hope that answers your question.
Dr Gilles RAULT, Roscoff CF Center
with the kind contribution of
Ms Geneviève Héry-Arnaud
Microbiologist, University Hospital, Brest