quinupristin-dalfopristin and Respiratory-Tract-Infections

Quinupristin/dalfopristin and RPR 106972 were active in vitro against a wide range of aerobic Gram-positive organisms including Enterococcus faecium. However, most isolates of Enterococcus faecalis were resistant or of intermediate sensitivity. Against Staphylococcus aureus quinupristin/dalfopristin was more active but for all other species the range of activity of the two drugs was the same or RPR 106972 was more active. RPR 106972 was also more active against the respiratory pathogens Haemophilus influenzae and Moraxella catarrhalis. Quinupristin/dalfopristin MICs for isolates of H. influenzae (1-8 mg/L) clustered around the breakpoint. There were differences in the quality of growth, but little difference in MICs or zone diameters was obtained on three different media: Mueller-Hinton (MHA), Iso-Sensitest (ISA), and Diagnostic Sensitivity Test (DST) agars. The addition of blood to the medium increased MICs 2- to 4-fold, with MHA showing the greatest increase, and reduced zone diameters around quinupristin/dalfopristin discs by 3-4 mm, with the greatest effect on ISA.

Topics: Anti-Bacterial Agents; Culture Media; Drug Therapy, Combination; Gram-Positive Bacteria; Gram-Positive Bacterial Infections; Haemophilus Infections; Haemophilus influenzae; Humans; Microbial Sensitivity Tests; Moraxella catarrhalis; Neisseriaceae Infections; Respiratory Tract Infections; Virginiamycin

Topics: Anaerobiosis; Anti-Bacterial Agents; Bacteria; Culture Media; Microbial Sensitivity Tests; Respiratory Tract Infections; Staphylococcus; Virginiamycin

The in-vitro activity of RP 59500, a new semisynthetic injectable streptogramin, was compared with that of erythromycin, rifampicin and ciprofloxacin against 189 Legionella spp. Rifampicin was the most active agent tested. RP 59500 was found to be more active than erythromycin against most strains, but less active than ciprofloxacin. Legionella pneumophila serogroups 1, 3, 4, 5 and 6 were more susceptible to RP 59500 than were L. pneumophila serogroups 2, 7, and 8. Legionella micdadei was the least susceptible species to RP 59500 and erythromycin. RP 59500 was similar in activity against isolates obtained from both patients and environmental sources. This activity was generally better than that of erythromycin.

Topics: Ciprofloxacin; Cross Infection; Drug Resistance, Microbial; Erythromycin; Humans; In Vitro Techniques; Legionella; Microbial Sensitivity Tests; Respiratory Tract Infections; Rifampin; Virginiamycin