Antibiotic Susceptibility of Haemophilus influenzae from Clinical Isolates

Abstract

Antibiotic susceptibility, β-lactamase activity and biotype of H. influenzae or H. parainfluenzae isolated from various clinical specimens from July 1982 to January 1984 were investigated. The result were as follows:
1. 231 strains of ABPC sensitive H. influenzae did not produce β-lactamase. 104 strains of H. influenzae were ABPC resistant, 101 of them produced β-lactamase and 3 of them did not produced.
2. 66 strains of β-lactamase producing H. influenzae were also resistant to SBPC, PIPC, MZPC.β-lactamase producing ABPC resistant strains were not resistant to cephems. CTX, CZX, CMX were very effective to β-lactamase producing ABPC resistant strains.
3. 5 strains of H. influenzae, which were resistant to CMZ, CTM by the disk diffusion method, were resistant to ABPC and MICs of CTM, CMZ, CTX, LMOX, AZT were elevated slightly.
4. Nitrocefin disk method and pH disk method could detect the β-lactamase of H. influenzae.
5. Marked differens of biotype distribution was not observed between β-lactamase producing ABPC resistant and β-lactamase non-producing ABPC sensitive H. influenzae.
6. Susceptibility pattern was almost identical, H. parainfluenzae isolated from respiratory tract with H. influenzae. 5 strains of H. parainfluenzae isolated from urinary tract were resistant to CTX, LMOX, AZT, but 2 strains of them produced β-lactamase.