Susceptibility of Haemophilus influenzae to piperacillin-tazobactam combinations: Interpretive criteria and quality control limits for standardized tests

A. L. Barry, P. C. Fuchs, J. H. Jorgensen, F. C. Tenover, S. D. Allen, D. J. Hardy, J. C. McLaughlin

Research output: Contribution to journalComment/debate

3 Scopus citations

Abstract

In vitro studies evaluated methods for testing the susceptibility of Haemophilus influenzae to piperacillin-tazobactam combinations. Ampicillin- resistant β-lactamase-nonproducing strains of H. influenzae may be presumed to be relatively resistant to combinations of piperacillin-tazobactam, even though they frequently appear to be susceptible by disk diffusion methods. Other ampicillin-resistant or -susceptible strains were predictably susceptible; i.e., 130 such strains gave zones of inhibition ≥26 mm in diameter, and MICs for these strains were ≤0.125/4.0 μg/ml (≤1.0/0.12 μg/ml when an 8:1 ratio was tested). A resistant category has yet to be defined. For quality control purposes, H. influenzae ATCC 49247 should give zones of inhibition 32 to 38 mm in diameter, and broth microdilution MICs should be 0.12/4.0 to 0.5/4.0 μg/ml.

Original languageEnglish (US)
Pages (from-to)751-753
Number of pages3
JournalJournal of clinical microbiology
Volume31
Issue number3
DOIs
StatePublished - 1993

ASJC Scopus subject areas

  • Microbiology (medical)

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