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AMPICILLIN-RESISTANT HÆMOPHILUS INFLUENZÆ TYPE B POSSESSING A TEM-TYPE β-LACTAMASE BUT LITTLE PERMEABILITY BARRIER TO AMPICILLIN

1975; Elsevier BV; Volume: 305; Issue: 7909 Linguagem: Inglês

10.1016/s0140-6736(75)91630-x

1474-547X

AntoneA. Medeiros, T. F. O'Brien,

Antibiotic Resistance in Bacteria

Ampicillin-resistant Hœmophilus inflenzœ type B have been reported only during the past year. Five clinical isolates from the U.S. and Germany all had the TEM-type β-lactamase which is known to be transferred widely among other gram-negative bacilli. Unlike those bacilli, however, the H. influenzæ cell had very little barrier to entry of penicillins. This greater permeability of the H. influenzæ cell to penicillins appeared to reduce the protective effect of its β-lactamase, in that acquisition of the TEM-type β-lactamase increased levels of resistance to penicillins much less for individual cells of H. influenzæ than for those of Escherichia coli. Large inocula of either species appeared highly resistant. The unusually low level of resistance of individual cells of H. influenzæ containing the TEM-type β-lactamase may have delayed their emergence or recognition, and has unresolved clinical implications.