[Changes in the sensitivity of pneumococci to antibiotics. Therapeutic consequences].

Streptococcus pneumoniae has a prominent role in infectious bronchopulmonary diseases. This organism is normally sensitive to a vast number of antibiotics. However, in recent years, acquired resistance against tetracyclines, macrolides, and, more recently, penicillins, has emerged. Since 1987, there is indeed a regular increase in the frequency of strains that have a lower sensitivity to penicillin G (less than 1% before 1986; 12% in 1990). However, this percentage of strains with a lower sensitivity is much more important among non-invasive as opposed to invasive organisms that are isolated from blood, pleural and spinal fluid cultures (3.3% in 1990). Among strains with abnormal sensitivity to penicillin G, there are very selective serotypes or serogroups: 4 types or groups (23, 19, 6 and 14) represent 80% of these strains. More than 80% of the strains of MIC greater than 2 mg/l are among only one stereotype, 23F. This abnormal sensitivity to penicillin G implies a modification of sensitivity to all beta-lactams, but MIC increase to a variable extent depending on the antiinfectious agent. The most efficient agents against strains of lower sensitivity are amoxicillin, imipenem and parenteral third generation cephalosporins. On the other hand, for all oral first, second and third generation cephalosporins, MIC increase to levels for which seric levels that are reached hardly demonstrate convincing efficiency. Even if resistance levels are less marked as shown by strains isolated from pulmonary infections as compared to what is seen in ENT, the trend in the development of abnormal sensitivity of pneumococci to beta-lactam agents urges the clinician to take into account these data in the therapeutic coverage of bronchopulmonary infections.