Staphylococcus aureus

Question

Hello,
The 2 last sputum analysis of my 8-year-old little son showed Staphylococcus aureus. However, no antibiotic was prescribed. A priori, the CF Center does not find this alarming. Is it because there are colonization thresholds?
Thank you for your answer.

Answer

Hello,

It is difficult to answer this without the context. Actually, a large proportion of the general population is Staphylococcus aureus healthy carrier on the skin and the respiratory tract. The presence of this organism in a CF patient, therefore, does not automatically follow that the germ is responsible for a respiratory infection causing more or less reversible lesions and symptoms requiring treatment. Surely we should be particularly vigilant in CF patients because of the risk of developing an infection with this germ is greater. To decide on a prescription of antibiotics, we should take in account the clinical context, including general symptoms (mood changes, loss of appetite, weight loss, fatigue, fever ...) or respiratory signs (change of cough, nasal and/or bronchial discharge, chest auscultation, even bronchopulmonary radiological signs if clinical signs incite to realize an X-ray) but also bacteriological results (count of germs, germ resistance to certain antibiotics ...).

To answer your question specifically, the commonly cited threshold for S. aureus is 10^5 colony forming units/mL threshold at which the infection could be attributed to it; but the entire clinical context prevails to make a decision.
I invite you to talk to your CF Center doctor who follows your child and will be able to give you the reasons for the no treatment decision.

Hoping to have answered your question.
Best regards,

Gilles RAULT, MD, Roscoff CF Center

01.02.2016