We read with great interest the study by Fanelli et al1 showing that the prolonged use of tetracycline antibiotic, commonly used to treat acne, lowered the incidence of colonization by Staphylococcus aureus and did not increase resistance to the tetracycline antibiotics, but these results should be taken cautiously. Apart from acne, there is another circumstance in which tetracycline antibiotics are prescribed over a long period, namely for the prevention of malaria. In this context, the use of doxycycline, 100 mg/d, is currently indicated to prevent malaria attack for travelers in areas where malaria is endemic. In particular, the French military routinely use doxycycline as malaria prophylaxis.