[Haemophilus influenzae: epidemiologic problems of antibiotic resistance to ampicillin, tetracycline, chloramphenicol, kanamycin].

Haemophilus species usually occur on mucous membranes of both the upper respiratory tract and oral cavity, in children mostly in the pharynx. In children and adults, Haemophilus influenzae has pathogenic properties. In 1973, the first ampicillin-resistant and beta-lactamase-producing strain was isolated. Since then, an increase in ampicillin resistance has been observed worldwide in different countries due, mostly, to beta-lactamase production. Thus, the latter should be examined on a systematic basis in all pathogenic strains. Prior to 1980, the incidence of ampicillin resistance was still below 100%. In the course of a joint French study, in which both the "Centre d'Etude des Haemofiles" and municipal hospitals and university clinics participated in 1985, 705 strains occurring in clinical infections have been isolated. 613 strains (86.9%) were susceptible to the antibiotics tested, in 92 strains (13%) resistance to one or several antibiotics was seen. Biotype I and serotype b constituted the major proportion of residual strains. Resistance to ampicillin, tetracycline, kanamycin, and chloramphenicol was observed in 11.2%, 9%, 6.8%, and 3.4% of the strains respectively. 11 different phenotypes of resistance have been considered feasible for the resistant strains. With one exception, resistance to ampicillin was invariably due to beta-lactamase production. On account of the level of incidence of ampicillin-resistant strains it is recommended that ampicillin no longer be used in the treatment of systemic infections due to H. influenzae.