Antibiotic resistance patterns among respiratory pathogens at a German university children's hospital over a period of 10 years

Abstract

Growing antimicrobial resistance among Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis is raising major concern worldwide. Strains of S. pneumoniae, H. influenzae and M. catarrhalis isolated from children with respiratory tract as well as invasive infection in a South-Western region of Germany between 1993 and 2002 were tested for susceptibility to common antibiotics including penicillins, cephalosporins and macrolides. A total of 2,362 S. pneumoniae, 2,501 H. influenzae, and 1,982 M. catarrhalis isolates were tested. Only two S. pneumoniae strains were found to be highly resistant to penicillin. The overall rate of intermediate resistance to penicillin was 3.5%. There was a significant increase in erythromycin resistance from 5% in 1993 to 12.2% in 2002 (P=0.001). No increase in ampicillin resistance was observed for H. influenzae over time. The rate of cefaclor resistance, however, increased from 4.5% to 11.8% (P<0.0001). Furthermore, a massive increase in erythromycin resistance from 26% to 40% was observed (P<0.0001). The vast majority of M. catarrhalis isolates were beta-lactamase positive, the minimal inhibitory concentration to ampicillin, however, exceeded only in 3% of all strains the cut-off of 1.5 mg/l. The erythromycin resistance rate of M. catarrhalis was 0.3%.

Conclusion: There is still a low rate of penicillin/ampicillin resistance in S. pneumoniae, and H. influenzae, but an alarming increase in resistance to erythromycin, and in H. influenzae a significant increase in cefaclor resistance was observed over the 10-year period in South-Western Germany.