In vitro activity of l-Ofloxacin against norfloxacin-resistant coagulase-negative staphylococci

Foleno, Barbara; Fu, Kwung P.

doi:10.1016/0732-8893(92)90109-7

Cited by 6 publications

(6 citation statements)

References 10 publications

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“…picillin and penicillin G. No cross-resistance to these other antibiotics was observed (table 5). These data are in agreement with our pre vious study [7] showing that levofloxacin was also active against norfloxacin-induced nor floxacin-resistant coagulase-negative staphy lococci at concentrations achievable in hu mans. This suggests levofloxacin may exhibit another mechanism of action against grampositive organisms.…”

Section: Resultssupporting

confidence: 82%

Induction of Resistance of <i>Streptococcus pneumoniae </i>to Quinolones in vitro

Lafredo¹,

Foleno²,

Fu³

1993

Chemotherapy

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Twelve strains of Streptococcus pneumoniae were serially exposed to increasing concentrations of levofloxacin, temafloxacin, ciprofloxacin and norfloxacin for five passages. Wild-type and passaged strains were tested for susceptibility to quinolones, macrolide and penicillin G. The MIC90 data showed a 2-fold increase for levofloxacin but a 32-fold increase for ciprofloxacin, a 16-fold increase for temafloxacin and an 8-fold increase for norfloxacin. Among 16 ciprofloxacin-induced resistant strains, 14 were susceptible to levofloxacin. No cross-resistance to other antibiotics was observed.

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Section: Resultssupporting

confidence: 82%

Induction of Resistance of <i>Streptococcus pneumoniae </i>to Quinolones in vitro

Lafredo¹,

Foleno²,

Fu³

1993

Chemotherapy

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“…When the susceptibility test results of this survey were compared with those of previous studies, there was little to no difference in the percentage of isolates of most species suscep-tible to the three quinolones. Although earlier studies indicated that nearly all staphylococci, including methicillin-resistant strains, were susceptible to these quinolones (7,8,23,28), our data are very comparable to those from more recent reports indicating the greatly reduced susceptibilities of methicillin-resistant strains (6,29). Enterococci could not be adequately evaluated because nearly half of the isolates were not identified to the species level.…”

Section: Methodssupporting

confidence: 48%

Prevalence of resistance to three fluoroquinolones: assessment of levofloxacin disk test error rates and surrogate predictors of levofloxacin susceptibility. AST Surveillance Group

Fuchs¹,

Barry²,

Brown³

1996

Antimicrob Agents Chemother

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More than 3,000 consecutive clinical bacterial isolates from 10 U.S. medical centers were subjected to standard broth microdilution and disk diffusion tests to determine their susceptibilities to levofloxacin, ofloxacin, D-ofloxacin, and ciprofloxacin. Levofloxacin was confirmed to be twice as active as ofloxacin and to have activity comparable to that of ciprofloxacin, with minor variations in activity against some species. The prevalence of resistant isolates was 7.1% to levofloxacin, 9.3% to ciprofloxacin, and 11.2% to ofloxacin. The susceptibilities of some species to the quinolones were less than those reported in previous studies. Pseudomonas aeruginosa isolates had the greatest variability in their susceptibilities to the three drugs between the participating centers. Two proposed zone size breakpoints for levofloxacin disk tests yielded similar low error rates. Ofloxacin and ciprofloxacin susceptibility test results correlated reasonably well with those of levofloxacin and could be used as surrogate indicators of levofloxacin susceptibility, but that resulted in some serious errors, and thus, direct testing of levofloxacin susceptibility is preferable. Replicate testing of standard quality control strains confirmed the established and proposed quality control parameters for all three quinolones tested.

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“…The pharmacokinetic properties of levofloxacin in humans are similar to those of ofloxacin, with high concentrations in serum (4.9 ,ug/ml; 350 mg orally), high tissue penetration and a terminal elimination half-life of 6 to 7 h (3,7,12). On the basis of such human pharmacokinetic data, it seems reasonable to characterize bacteria for which the MICs are <2.0 ug/ml as being susceptible and those for which the MICs are >4.0 ,ug/ml as being resistant.…”

mentioning

confidence: 90%

“…Ofloxacin is a fluoroquinolone antimicrobial agent that exists as two optically active isomers because of the asymmetric center at C-3 of the oxazine ring. Levofloxacin (l-ofloxacin) is the more active of the two isomers and has pharmacokinetic properties similar to those of ofloxacin (3,4,7,12,13). The spectrum of antibacterial activity of levofloxacin is similar to that of ofloxacin, but levofloxacin is two to four times more potent (2-4, 6, 11, 12).…”

mentioning

confidence: 99%

“…Previous studies have recommended the use of 5-,ug disks and interpretive criteria of .12 mm for resistance and .16 mm for susceptibility for ofloxacin (5,6). Because levofloxacin and ofloxacin have very similar spectra of activity (2)(3)(4)(5)(6)(11)(12)(13), it seems reasonable to select the same disk potency for both agents. Identical zone size interpretive criteria apply to both disks.…”

mentioning

confidence: 99%

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Levofloxacin disk potency and tentative interpretive criteria for susceptibility tests

1993

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In vitro activity of l-Ofloxacin against norfloxacin-resistant coagulase-negative staphylococci

Cited by 6 publications

References 10 publications

Induction of Resistance of <i>Streptococcus pneumoniae </i>to Quinolones in vitro

Induction of Resistance of <i>Streptococcus pneumoniae </i>to Quinolones in vitro

Prevalence of resistance to three fluoroquinolones: assessment of levofloxacin disk test error rates and surrogate predictors of levofloxacin susceptibility. AST Surveillance Group

Levofloxacin disk potency and tentative interpretive criteria for susceptibility tests

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