[Show abstract][Hide abstract] ABSTRACT: Fourteen pneumococcal strains isolated in three nationwide studies were characterized for amino acid changes in the enzymes GyrA, GyrB, ParC and ParE, and for the in vitro activity of eight fluoroquinolones and the new non-fluorinated quinolone BMS 284756. Gemifloxacin and BMS 284756 exhibited the best in vitro activity against all 14 isolates tested. In nine of the 14 isolates mainly classical alterations in ParC (D83N/Y, S79Y/F), as well as rarer alterations such as S80P and D78N, contributed to the decreased susceptibility to fluoroquinolones. In two of the 14 isolates the classical alteration in GyrA (S81F) was found. In only one isolate did alterations in ParC and GyrA exist in parallel.
[Show abstract][Hide abstract] ABSTRACT: Of the 419 Moraxella catarrhalis isolates collected during the 1997-1999 European SENTRY surveillance study, 385 (92%) were beta-lactamase positive. Twenty-two (5.7%) produced BRO-2 beta-lactamase. Twenty-one new mutations were found in the putative promoter region of the bro genes. Nineteen percent of all isolates tested were complement sensitive. Resistance to beta-lactams is not linked to the phylogenetic lineages associated with susceptibility to complement.
[Show abstract][Hide abstract] ABSTRACT: The in vitro activities of the novel des-fluoro(6) quinolone BMS-284756, ciprofloxacin, gatifloxacin and moxifloxacin were tested against 248 genetically defined Staphylococcus aureus isolates, comprised of 116 unrelated S. aureus, seven heterogeneous vancomycin-intermediate S. aureus (hetero-VISA) strains and 125 clonally related MRSA. All strains were susceptible to BMS-284756 at an investigational breakpoint of 1 mg/L. Reserpine did not decrease the MIC of BMS-284756 in any of the strains tested. The novel des-fluoro(6) quinolone BMS-284756 showed a significantly increased anti-staphylococcal activity.
[Show abstract][Hide abstract] ABSTRACT: Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus isolates were exposed to subinhibitory MICs of ciprofloxacin, sparfloxacin, gatifloxacin, moxifloxacin, clinafloxacin, and gemifloxacin during a 10-day period. Subculturing led to resistance development, regardless of the initial potencies of the quinolones. None of the quinolones was associated with a significantly slower rate of resistance development.
[Show abstract][Hide abstract] ABSTRACT: A relationship between resistance to methicillin and resistance to fluoroquinolones, rifampin, and mupirocin has been described
forStaphylococcus aureus. Differences in resistance rates may be explainable by a higher spontaneous mutation rate (MR) or a faster development of
resistance (DIFF) in methicillin-resistant S. aureus (MRSA). No differences in MR, DIFF, and mutations ingrlA and gyrA were detected between methicillin-susceptible S. aureus and MRSA. The higher resistance rates in MRSA are not the result of hypermutability of target genes or a faster emergence
of different mutations and may be the consequence of clonal spread of multiresistant MRSA.
[Show abstract][Hide abstract] ABSTRACT: The polymerase chain reaction (PCR) was used to study the prevalence of the macrolide resistance genes ermA , ermB , ermC , msrA/msrB , ereA and ereB , in 851 clinical isolates of Staphylococcus aureus and 75 clinical isolates of Enterococcus faecium that were erythromycin resistant. The isolates were from 24 European university hospitals. In S. aureus , the ermA gene was more common in methicillin-resistant S. aureus (MRSA) isolates (88%) than in methicillin-susceptible S. aureus (MSSA) isolates (38%), and occurred mainly in strains with constitutive MLS B expression. In contrast, ermC was more common in MSSA (47%) than in MRSA (5%), occurring mainly in strains with inducible expression. The ereB gene was only found in MRSA isolates expressing a constitutive MLS B phenotype (1%). The ereA gene was not detected. Macrolide resistance by efflux due to the msrA / msrB gene was only detected in MSSA isolates (13%). In contrast to S. aureus , erythromycin resistance in E. faecium was almost exclusively due to the presence of the ermB gene (93%).