Of the 50 strains of beta-lactamase-producing Branhamella catarrhalis
isolated at Saint Joseph's Hospital (Paris) that were studied, 94% pro
duced BRO-1 type beta-lactamase and 6% produced the BRO-2 type. We exa
mined the transfer of BRO-1 and BRO-2 genes and found that, among 7 do
nor strains producing BRO-1, all were able to transfer the gene for BR
O-1 production by conjugation. Of the 4 donor strains producing BRO-2,
2 were able to transfer the gene for BRO-2 production by conjugation.
Three BRO-1 beta-lactamase-producing transformants were obtained from
total DNA extracted from 3 strains producing BRO-1. Plasmid bands wer
e demonstrated in strains of B. catarrhalis, but no change in plasmid
profiles was seen in beta-lactamase-positive recombinants, supporting
previous studies that suggested the beta-lactamases are chromosomal. l
it vitro activity of oral beta-lactams was tested for 67 strains of B.
catarrhalis (56 beta-lactamase-producing strains). Cefixime, cefpodox
ime and the combination ampicillin-clavulanic acid were very active ag
ainst the beta-lactamase-producing strains. BRO-1 beta-lactamase appea
rs to affect the activity of cefaclor, cefuroxime and loracarbef. BRO-
2 beta-lactamases have no effect on the activity of these cephalospori
ns. Cefixime and cefpodoxime seemed the least affected by beta-lactama
se production.