We analyzed 62 clinical isolates of streptogramin A-resistant (SGA r ) Staphylococcus aureus collected between 1981 and 2001 in 14 hospitals located in seven French cities. These isolates, including five with decreased susceptibility to glycopeptides, were distributed into 45 antibiotypes and 38 SmaI genotypes. Each of these genotypes included between 1 and 11 isolates, the SmaI patterns of which differed by no more than three bands. Although numerous clones were identified, we observed the spread of monoclonal isolates either within the same hospital or within hospitals in distinct cities and at large time intervals. Hybridization with probes directed against 10 SGA r genes (vatA, vatB, vatC, vatD, vatE, vgaA, vgaB, vgaAv, vgbA, and vgbB) revealed six patterns: vgaAv (21 isolates), vatA-vgbA (24 isolates), vgaAv-vatB-vgaB (14 isolates), vgaAv-vatA-vgbA (1 isolate), vgaAv-vatA-vgbA-vatB-vgaB (1 isolate), and vgaA (1 isolate). We detected at least one SGA r determinant in all of the tested isolates. vgaAv, which is part of the recently characterized transposon Tn5406, was found in 59.7% of the tested isolates. Of the 16 streptogramin B-susceptible isolates, 14 carried vgaAv alone and were susceptible to the mixtures of streptogramins, whereas the 2 isolates carrying vgaAv-vatB-vgaB were resistant to these mixtures. vatA-vgbA was found on plasmids of the same apparent size in 26 (42%) of the tested clinical isolates from 18 unrelated SmaI genotypes. The possible dissemination of some of the multiple clones characterized in the present study with an expected increased selective pressure of streptogramins following the recent licensing of Synercid (quinupristin-dalfopristin) must be carefully monitored.Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen worldwide. Glycopeptides have been the reference drugs for the treatment of MRSA infections (16,21,30). After the emergence of clones with decreased susceptibility to these antibiotics, first reported as sporadic cases in several countries and more recently also as outbreaks, alternative treatments such as quinupristin-dalfopristin (Synercid) have been promoted (17,21,33). Quinupristin and dalfopristin are derivatives of pristinamycins IA and IIA, respectively (10). Quinupristin-dalfopristin is an injectable, semisynthetic, mixture with a synergistic activity against most gram-positive pathogens. Since 1999, quinupristin-dalfopristin has been available for use in hospitals for the treatment of infections caused by gram-positive cocci that are resistant to other antibiotics.Quinupristin-dalfopristin and the natural antibiotics produced by streptomycetes, such as streptogramin, pristinamycin, synergistin, mikamycin, and virginiamycin, are mixtures of two classes of compounds, A and B, with distinct primary structures (10, 14). The A compounds are polyunsaturated cyclic macrolactones, and the B compounds are cyclic hexadepsipeptides. Both types of compounds bind different targets in the peptidyltransferase domain of the 23S ribosoma...

A DNA macroarray containing 465 intragenic amplicons was designed to identify Staphylococcus aureus at the species level and to type S. aureus isolates. The genes selected included those encoding (i) S. aureus-specific proteins, (ii) staphylococcal and enterococcal proteins mediating antibiotic resistance and factors involved in their expression, (iii) putative virulence proteins and factors controlling their expression, and (iv) proteins produced by mobile elements. The macroarray was hybridized with the cellular DNAs of 80 S. aureus clinical isolates that were previously typed by analyses of their antibiograms and SmaI patterns. The set selected contained unrelated, endemic, and outbreak-related isolates belonging to 45 SmaI genotypes. In a gene content dendrogram, the 80 isolates were distributed into 52 clusters. The outbreak-related isolates were linked in the same or a closely related cluster(s). Clustering based on gene content provided a better discrimination than SmaI pattern analysis for the tested mecA ؉ isolates that were endemic to Europe. All of the antibiotic resistance genes detected could be correlated with their corresponding phenotypes, except for one isolate which carried a mecA gene without being resistant. The 16 isolates responsible for bone infections were distinguishable from the 12 isolates from uninfected nasal carriers by a significantly higher prevalence of the sdrD gene coding for a putative SD (serine-aspartate) adhesin (in 15 and 7 isolates, respectively). In conclusion, the macroarray designed for this study offers an attractive and rapid typing method which has the advantage of providing additional information concerning the gene content of the isolate of interest.The best known staphylococcal species is Staphylococcus aureus, by virtue of its frequent and highly versatile pathogenicity in humans and animals. Isolates belonging to this species are responsible for suppurative infections and syndromes provoked by toxins. Excluding pathologies caused by toxins such as enterotoxins and exfoliative or toxic shock syndrome toxins (20), the pathology of a staphylococcal infection is attributable not to a single factor but to the coordinated actions of several factors whose expression is controlled by several regulatory systems (3,26,29,30). S. aureus is one of the most common causes of nosocomial infections. The emergence of such infections is of particular concern since most isolates, such as methicillin-resistant S. aureus (MRSA), are resistant to several antibiotics (4, 28) and because the spread of these strains in hospitals often increases the overall incidence of nosocomial S. aureus infections in the institution. MRSA clinical isolates with decreased susceptibilities to glycopeptides (1, 17) threaten to compromise our ability to treat hospital-acquired S. aureus infections.S. aureus typing is a useful adjunct in several clinical settings, in addition to its use during dramatic acute outbreaks. Despite the use of several phenotypic and genotypic methods (antibiotyping, phage typi...

According to the French Society of Microbiology, Staphylococcus aureus isolates are suspected to have decreased susceptibility to glycopeptide(s) when at least one colony is able to grow from an inoculum of 10 microL of 2 McFarland bacterial suspension plated on Mueller-Hinton agar containing 5 mg/L teicoplanin and incubated for 48 h at 35-37 degrees C. We analysed 89 methicillin-resistant S. aureus isolates (MRSA), collected in 2000-2001 from 24 hospitals located in 18 French cities, which were able to grow on this selective medium. These isolates were distributed into six groups on the basis of their glycopeptide resistance phenotypes: (A) glycopeptide susceptible (GSSA, 21 isolates); (B) heterogeneous teicoplanin intermediately resistant (hetero-TISA, 24 isolates); (C) heterogeneous and intermediately resistant to both glycopeptides, teicoplanin and vancomycin (hetero-GISA, six isolates); (D) heterogeneous vancomycin intermediately resistant/teicoplanin intermediately resistant (hetero-VISA/TISA, 30 isolates); (E) GISA (four isolates); (F) TISA (four isolates). Despite the persistent decrease in gentamicin-resistant MRSA isolates in French hospitals since 1993, their prevalence is very high in groups D, E and F. Moreover, most of the group C, D and E isolates exhibiting decreased susceptibility to both glycopeptides belong to the same major SmaI genotype, which has been detected in Europe since at least 1989.