[Bacterial infectious agents implicated in lower respiratory tract infections in general practice]

The consensus of the French Society of Infectious Diseases established in 1991 states that Streptococcus pneumoniae and Haemophilus influenzae are the main causal agents of community-acquired lower airway infections and that antibiotics constitute the "prudent" solution in case of acute bronchitis which persists more than one week or in case of pneumonia in "fragile" at-risk adults. The efficacy of these "probabilistic" recommendations depends on the epidemiology of the infectious agents. The objective of this study was to identify the causal germs in lower airway infections and determine their sensitivity to the antibiotics recommended in the consensus statement. The study was conducted from December to March, in 1992 and 1993. Expectoration samples were obtained from 111 cases including 29 patients with chronic bronchitis. Seventy different strains were isolated including 24 strains of H. influenzae (3 betalactamase producers), 15 strains of S. pneumoniae (1 with reduced sensitivity to peni G: MIC = 1 mu/ml), 9 strains of S. aureus (2 methicillin resistant), and 8 strains of Branhamella catarrhalis (6 betalactamase producers). The number of positive serologies was very low: 5 Chlamydiae pneumoniae, 2 Chlamydiae trachomatis and 1 Mycoplasma pneumoniae. In conclusion H. influenzae is the most frequent germ; S. pneumoniae infections with reduced peni-G sensitivity and atypical germs are uncommon. The consensus recommendations appear to be adapted to the bacterial flore causing community-acquired lower airway infection in healthy and at-risk subjects.