title: Utility of the Etest GRD for detecting Staphylococcus aureus with reduced susceptibility to glycopeptides in cystic fibrosis patients.
abstract: Glycopeptide-intermediate S. aureus (GISA), particularly heterogeneous GISA (hGISA), remain difficult to detect in the routine practice of medical microbiology. Novel tools have been evaluated comparatively to the population analysis profile-area under the curve (PAP-AUC) reference method for detecting GISA/hGISA. Among them, the Etest GRD showed relatively high specificity (85.8-97%) and negative predictive value (97%) but lower sensibility (57-95%) and positive predictive value (30.8%). We investigated the utility of the Etest GRD for detecting GISA/hGISA among 180 strains isolated from 106 cystic fibrosis (CF) patients. Etest GRD was performed on all isolates, and those exhibiting a GISA/hGISA phenotype were further tested by PAP-AUC and other agar routine assays for GISA/hGISA detection. The Etest GRD allowed the detection of 15 GISA/hGISA strains, of which eight were confirmed by the reference method. Despite the 3.9% level of false positive results, the Etest GRD constitutes a useful routine tool for detecting GISA/hGISA overlooked by other routine assays, two strains being detected by the Etest GRD only. GISA/hGISA represented 7.7% of MRSA and 2.1% of MSSA, and were found in 4.7% of CF patients colonized/infected by S. aureus, which is the highest rate reported to date in this population.
authors: Hôpital Arnaud de Villeneuve, Service de Pédiatrie Générale, Maladies Infectieuses, Immunologie Clinique, Centre Hospitalier Régional Universitaire de Montpellier, 371, Avenue du Doyen Gaston Giraud, 34295, Montpellier Cedex 5, France.
authors: A
authors: A
authors: Filleron
authors: R
authors: R
authors: Chiron
authors: M-E
authors: ME
authors: Reverdy
authors: H
authors: H
authors: Jean-Pierre
authors: O
authors: O
authors: Dumitrescu
authors: L
authors: L
authors: Aleyrangues
authors: F
authors: F
authors: Counil
authors: E
authors: E
authors: Jumas-Bilak
authors: H
authors: H
authors: Marchandin
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003550:Cystic Fibrosis / Q000150:complications*; D024881:Drug Resistance, Bacterial; D005189:False Positive Reactions; D006020:Glycopeptides / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides