[Pneumococci with diminished sensitivity to penicillin in pneumopathies. Clinical consequences]

INCREASING PREVALENCE: Since 1988, French clinicians have been faced with an increasing prevalence of penicillin-resistant pneumococcal pneumonia. In 1996, the percentage of strains with reduced susceptibility to penicillin reached more than 40% and the number of multiresistant strains has increased steadily.

Despite this apparently alarming situation, the clinical impact is not obvious. Different clinical studies have demonstrated that mortality due to pneumococcal pneumonia has not been affected by the development of resistant strains, eventually because the strains involved belong to less invasive serotypes than penicillin susceptible pneumococci.

The preferential distribution of penicillin resistance among less invasive serotypes might explain the development of resistance in carriage strains more often exposed to antibiotic selection and the greater risk for immunodepressed subjects to acquire these strains.

To date, first-line antibiotic therapy with amoxicillin at the dose of 3g/24 h remains valid for the great majority of cases. Use of much higher dosages or other antibiotics for pneumococcal pneumonia would only be rational when penicillin minimum inhibitory concentrations are above 2 mg/l.