Levofloxacin disk potency and tentative interpretive criteria for susceptibility tests

Pfaller, Michael A.; Barry, Arthur L.; Fuchs, Peter

doi:10.1128/jcm.31.7.1924-1926.1993

Cited by 13 publications

(17 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2) and Table 1 list the results of the predictor panel evaluation of levofloxacin. Two previously presented studies (4,15) selected zone diameter criteria generated from a population of bacteria that contained only 5.7 to 6.7% levofloxacin-resistant strains. Our organism panel contained 53.0% of the strains that were potentially resistant to levofloxacin (MIC, Ն8 g/ml) and an additional 35 strains (11.7%) that required an intermediate levofloxacin MIC of 4 g/ml.…”

Section: Resultsmentioning

confidence: 99%

“…Ofloxacin is a fluoroquinolone that contains a chiral carbon at the C-3 position of the oxazine ring. Levofloxacin (formerly DR-3355) is the ofloxacin optical isomer which has a greater antimicrobial spectrum and has been reported to be 2-to 128-fold more active than racemic ofloxacin (4,5,15,17). As expected of optical isomers, levofloxacin and ofloxacin share similar pharmacokinetic properties, so the MIC breakpoints (Յ2 g/ml as susceptible and Ն8 g/ml as resistant) utilized for ofloxacin (7) and most other fluoroquinolones (12,13) should also be applicable to levofloxacin (4,15).…”

mentioning

confidence: 99%

“…Previously published susceptibility testing interpretive criteria for levofloxacin (4,15) and sparfloxacin (6,9) have been determined with collections of test organisms that were predominantly susceptible to these fluoroquinolones. Typically, less than 10% of all organisms tested were resistant to levofloxacin (4,15) and sparfloxacin (6). The study that tested the highest proportion of resistant organisms (34.5%) against sparfloxacin was reported by Kayser and Wust (9).…”

mentioning

confidence: 99%

“…A collec-tion of organisms that contains an underrepresentative number of antimicrobial agent-resistant organisms may lead to interpretive criteria that overestimate susceptibility (1). In order to avoid this bias with these fluoroquinolones, the disk diffusion susceptibility criteria proposed in earlier studies (4,6,15) were modified on the basis of the results of tests with a predictor panel (1) of organisms collected worldwide (12,13). Bacterial strains.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Suggested modifications for disk diffusion susceptibility testing criteria for levofloxacin and sparfloxacin following tests with a predictor panel of ciprofloxacin-resistant clinical isolates

Sutton

Jones

1995

J Clin Microbiol

View full text Add to dashboard Cite

A predictor panel of 300 clinical bacterial isolates (200 resistant to ciprofloxacin) was used to compare 5-g disk diffusion test results with the MICs of ofloxacin (control), levofloxacin, and sparfloxacin. Regression analysis demonstrated high correlations between the methods for all three fluoroquinolones (r Ն 0.95). In order to minimize disk diffusion testing errors among the fluoroquinolone-resistant strains, the following modifications to previously proposed or published interpretive criteria were suggested: for levofloxacin, susceptible at Ն17 mm (Յ2 g/ml) and resistant at Յ13 mm (Ն8 g/ml); for sparfloxacin, susceptible at Ն20 mm (Յ1 g/ml) and resistant at Յ16 mm (Ն4 g/ml). The study control drug, ofloxacin, did not appear to possess a significant error rate (5% minor error) when fluoroquinolone-resistant strains were tested, and no modifications were proposed. Under these proposed interpretive criteria, the absolute categorical agreements between standardized susceptibility testing methods for levofloxacin and sparfloxacin results were 91.3 and 94.0%, respectively (Յ0.3% major errors and nil very major errors).

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Suggested modifications for disk diffusion susceptibility testing criteria for levofloxacin and sparfloxacin following tests with a predictor panel of ciprofloxacin-resistant clinical isolates

Sutton

Jones

1995

J Clin Microbiol

View full text Add to dashboard Cite

show abstract

“…Similarly, we evaluated only 58 isolates because only ϳ4% of Enterobacteriaceae isolates have MICs in the range that we desired to evaluate. It should be noted that the historical fluoroquinolone disk diffusion breakpoints were established using a set of isolates with a very limited number of resistant strains, 9 for ciprofloxacin (7) and 31 total (Gram-positive and Gram-negative strains) for levofloxacin (6). In summary, we demonstrated that the ciprofloxacin and levofloxacin disk and Etest methods perform reasonably well with the 2019 CLSI breakpoints, but laboratories should be cognizant of minor errors, particularly for isolates with disk or Etest results near the breakpoint.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Ciprofloxacin and Levofloxacin Disk Diffusion and Etest Using the 2019 Enterobacteriaceae CLSI Breakpoints

2019

View full text Add to dashboard Cite

In 2019, the Clinical and Laboratory Standards Institute (CLSI) published revisions to the Enterobacteriaceae ciprofloxacin and levofloxacin breakpoints. We evaluated the performance of disk diffusion and Etest compared to that of reference broth microdilution by use of the revised breakpoints. Fifty-eight Enterobacteriaceae isolates with ciprofloxacin MICs of 0.5 g/ml or 1.0 g/ml on initial testing were specifically selected for evaluation. These MICs are susceptible by the 2018 breakpoints and not susceptible by the 2019 breakpoints. For ciprofloxacin disk diffusion, the categorical agreement (CA) was 46.6%, with 0 very major errors (VME), 4 major errors (ME) (21.1%), and 27 minor errors (mE) (46.6%) using the 2019 CLSI disk breakpoints. For levofloxacin, the CA was 72.4%, with 0 VME, 0 ME, and 16 mE (27.6%) using the 2019 CLSI disk breakpoints. Using an error rate-bound evaluation method, levofloxacin but not ciprofloxacin disk diffusion yielded an acceptable minor error rate of Ͻ40% for isolates with an MIC plus or minus 1 doubling dilution of the intermediate breakpoint. For Etest compared to the reference broth microdilution, the essential agreement was 100% for both ciprofloxacin and levofloxacin and the CA was 81.0% and 65.5%, respectively. No VME or ME were observed by Etest, and 11 minor errors for ciprofloxacin (19.0%) and 20 (34.5%) for levofloxacin were observed. By the error rate-bound method, the minor error rate for ciprofloxacin was acceptable, but minor error rates for levofloxacin remained outside the acceptance range (i.e., 42.6% for isolates with an MIC within 1 dilution of the breakpoint). In general, the disk diffusion and Etest methods performed well with this challenging collection of isolates, although laboratories must be aware of minor errors, particularly for isolates with results near the breakpoint.

show abstract

Interpretive criteria and quality control for antimicrobial susceptibility tests of levofloxacin

Barry

Fuchs

Tenover³

et al. 1994

Eur. J. Clin. Microbiol. Infect. Dis.

View full text Add to dashboard Cite

To confirm preliminary interpretive breakpoints for prototype 5 micrograms levofloxacin disks, 490 strains were tested in vitro using commercially manufactured disks. For in vitro susceptibility testing, 5 micrograms levofloxacin disks can be used with interpretive criteria of < or = 12 mm for resistant (MIC > or = 8.0 micrograms/ml) and > or = 16 mm for susceptible (MIC < or = 2.0 micrograms/ml). Proposed quality control limits for tests of levofloxacin are as follows: Escherichia coli ATCC 25922, zones 29-37 mm or MIC 0.008-0.03 microgram/ml; Pseudomonas aeruginosa ATCC 27853, zones 19-26 mm or MIC 0.5-2.0 micrograms/ml; Staphylococcus aureus ATCC 25923, zones 24-31 mm; Staphylococcus aureus ATCC 29213, MIC 0.06-0.25 microgram/ml and Enterococcus faecalis ATCC 29212, MIC 0.25-2.0 micrograms/ml.

show abstract

Levofloxacin disk potency and tentative interpretive criteria for susceptibility tests

Cited by 13 publications

References 12 publications

Suggested modifications for disk diffusion susceptibility testing criteria for levofloxacin and sparfloxacin following tests with a predictor panel of ciprofloxacin-resistant clinical isolates

Suggested modifications for disk diffusion susceptibility testing criteria for levofloxacin and sparfloxacin following tests with a predictor panel of ciprofloxacin-resistant clinical isolates

Evaluation of Ciprofloxacin and Levofloxacin Disk Diffusion and Etest Using the 2019 Enterobacteriaceae CLSI Breakpoints

Interpretive criteria and quality control for antimicrobial susceptibility tests of levofloxacin

Contact Info

Product

Resources

About