[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 β-lactamase positive. Twenty-two
(5.7%) produced BRO-2 β-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 β-lactams is not linked to the phylogenetic
lineages associated with susceptibility to complement.
Full-text · Article · May 2002 · Journal of Clinical Microbiology
[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.
No preview · Article · Mar 2002 · Journal of Antimicrobial Chemotherapy
[Show abstract][Hide abstract] ABSTRACT: Of the 419 M. 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. Analysis of the in-vitro activities of 28 different antibiotics against all 419 M. catarrhalis isolates showed that BRO-1-producing isolates were more resistant to penicillins, some cephalosporins than BRO-2-producing strains. These latter strains have a 21-bp deletion in the putative regulatory region of the bro2 gene. Twenty-one additional new mutations were found in the putative regulatory region of the bro genes, which did not have an observable effect on the MIC-value distributions among the groups of BRO-1- and BRO-2-producing isolates. Nineteen percent of the 419 tested isolates were complement-sensitive. The distributions of beta-lactamase-negative and beta-lactamase-positive strains and of BRO-1- and BRO-2-producing strains in the two complement populations were comparable. Thus, in M. catarrhalis, resistance to antibiotics is not linked to the phylogenetic line-ages associated with susceptibility to complement.
No preview · Article · Jan 2002 · Chemotherapie Journal
[Show abstract][Hide abstract] ABSTRACT: Streptococcus pneumoniae, Streptococcus pyogenes, andStaphylococcus 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 possible antiseptic resistance in S. aureus isolates can be mediated for example by the efflux proteins QacA, QacB and QacC. In a study with 297 MRSA and 299 MSSA from 24 European University hospitals, 42% of all isolates contained qacA or qacB, respectively, while only in 5,8% of all isolates qacC could be detected. Thereby, 62% of the MRSA and 12% of the MSSA contained the qacA/B genes. Regarding qacC no difference between MRSA and MSSA could be detected. In 1% of the isolates both genes, qacA/B and qacC, were present. The great prevalence of qacA/B may be explained by the selective pressure of antiseptic agents or by a cospreading with widespread resistance plasmids in MRSA.
[Show abstract][Hide abstract] ABSTRACT: Streptococcus pneumoniae isolates (n = 1191) were collected during the 1997-1999 European SENTRY surveillance study. In addition to susceptibility data, a molecular epidemiological survey of their mechanisms of resistance to macrolides, tetracyclines, sulfamethoxazole/trimethoprim and quinolones was provided. Seventy-three percent of the European S. pneumoniae isolates resistant to erythromycin carried the erm(B) gene, while the remaining 27 % possessed the mef(A) gene. All tetracycline-resistant isolates carried the tet(M) gene. The trimethoprim resistant isolates possessed an Ile-100Leu alteration in the dihydrofolate reductase, while sulfonamide resistance was associated with duplication of amino acids in dihydropteroate synthase encoded by sulA.Classical alterations in GyrA (Ser 81→Phe or Tyr) and ParC (Ser 79→Phe and Asp 83→Asn) and efflux contributed to the decreased quinolone susceptibility in four isolates with elevated levofloxacin MICs.
No preview · Article · Jan 2001 · Chemotherapie Journal
[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.
Full-text · Article · Dec 2000 · Antimicrobial Agents and Chemotherapy
[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%).