%0 Journal Article %A Sykes, R. B. %A Matthew, M. %A O’Callaghan, Cynthia H. %T R-FACTOR MEDIATED β-LACTAMASE PRODUCTION BY HAEMOPHILUS INFLUENZAE %D 1975 %J Journal of Medical Microbiology, %V 8 %N 3 %P 437-441 %@ 1473-5644 %R https://doi.org/10.1099/00222615-8-3-437 %I Microbiology Society, %X SUMMARY Production of β-lactamase by 15 strains of Haemophilus influenzae has been investigated. All the strains produce a constitutive β-lactamase, which readily hydrolyses penicillin G, ampicillin, and cephaloridine. The β-lactamase produced by these strains is indistinguishable from the type-IIIa enzyme commonly found in strains of Escherichia coli. The β-lactamase gene has been transferred from the enzyme-producing strains of Haemophilus to strains of H. parainfluenzae and a strain of E. coli. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-8-3-437