Ampicillin-resistant haemophilus influenzae infections in Japan

Keizo Matsumoto, Harumi Shishido, Susumu Mitsuhashi, Matsuhisa Inoue, Hisashi Nakazawa, Takehito Nakabayashi, Fumio Nagahama, Kiyo Nishioka, Tamotsu Takishima, Suzuko Uehara, Akira Nakamura, Tomomichi Kurosaki, Nozomu Kosakai, Toyoko Oguri, Ken Ichi Yamaki, Tatsuo Satake, Fumio Miki, Kenzo Shiota, Tadashi Nishimura, Rinzo SoejimaYoshihito Niki, Chikara Nakahama, Masao Kuwahara, Yukio Nishimoto, Kohei Hara, Keizo Yamaguchi, Mitsuo Kaku

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


To clarify the epidemiology and the resistant mechanisms of ampicillin-resistant Haemophilus influenzae in Japan we conducted a multicenter study involving 11 hospitals. The microbiological studies were done in the Department of Microbiology, Gunma University. Ampicillin-resistance was considered present when the H. influenzae were β-lactamase producing or required an MIC equal or greater than 1.56 μg/ml at 106 CFU/ml. Ampicillin-resistant H. influenzae were first isolated in Tokyo and Chiba 1975, and in Sendai 1976. Subsequently similar organisms were isolated in other parts of Japan. The frequency of isolation of ampicillin-resistant H. influenzae from clinical specimens ranged between 5.9~21% with a mean of 12.4%. The general trend was one of an increasing frequency year after year. In the present study the highest MIC was 50 μg/ml and the peak was at 6.25 μg/ml. The β-lactamase activity ranged from 0.14 to 1.56 units (mean±SD=0.6±0.36). The types of β-lactamase isolated in this study belonged to penicillinase type I using MITSUHASHI's classification or TEM type by RICHMOND'S classification, Sensitivity to chloramphenicol was determined in 92 β-lactamase-producing strains of H. influenzae. Four (4.3%) strains were found to be resistant. Experimental conjugation was done in 6 strains of β-lactamase-producing H. influenzae resistant to ampicillin and tetracycline. Ampicillin resistant factors were successfully transferred to E. coli in 2 strains. However, resistance to tetracycline was not transferable. The results of this first multicenter study on the epidemiology of ampicillin-resistant H. influenzae in Japan indicated that, like in other countries, the problem is on the increase. It is important therefore that such studies should be continued.

Original languageEnglish
Pages (from-to)673-681
Number of pages9
Issue number8
Publication statusPublished - 1985
Externally publishedYes

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Infectious Diseases
  • Pharmacology
  • Drug Discovery
  • Oncology


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