The reemergence of gentamicin-susceptible (Gen s ) methicillin-resistant Staphylococcus aureus (MRSA) isolates in France between 1992 and 1996 was investigated using a phylogenetic approach (multiprimer randomly amplified polymorphic DNA typing). Eighty-six percent (65 of 85) of the French strains were grouped into one phylogenetic cluster within which all but one Gen s strain were grouped into a subcluster. Thus, the reemergence of Gen s MRSA strains in France was likely due to the spread of one specific clone which belonged to a cluster comprising most French gentamicin-resistant (Gen r ) strains. This suggests that the Gen s clone has emerged from a Gen r strain of this cluster.

Resistance to ampicillin without β-lactamase production is not a frequent occurrence among Haemophilus influenzaestrains. This kind of resistance is encountered in unencapsulated strains isolated from bronchial secretions and ear, nose, and throat specimens and is exceptional in H. influenzae type b. We studied 29 of these strains from various areas in France and 2 reference strains. Strains were compared by using ribotyping, arbitarily primed PCR with two primers, and pulsed-field gel electrophoresis. Each technique enabled the identification of 20 to 23 different patterns among the 31 strains. The combination of the different patterns for the strains obtained by the different techniques provided 27 distinct profiles. According to these results, it seems that the clonal propagation of these resistant strains does not occur.

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