Antibiotic resistance of pneumococci in Norway

A collection of 178 pneumococcal isolates found in Norway during the period 1987-1994 were tested for their susceptibility to benzylpenicillin, macrolides (azithromycin, clarithromycin, dirithromycin, erythromycin, roxithromycin, spiramycin), fluoroquinolones (ciprofloxacin, sparfloxacin), imipenem, chloramphenicol, and vancomycin by a standard agar dilution procedure. To benzylpenicillin, two strains (1%) showed resistance and 14 strains (8%) intermediate susceptibility. Towards erythromycin, eight strains (4%) showed resistance and four strains (2%) intermediate susceptibility. Cross-resistance was demonstrated among the macrolides. Among the fluoroquinolones, intermediate susceptibility occurred with 42% of the isolates for sparfioxacin and 90% for ciprofloxacin; to the latter 5.1% proved resistant. The sum of intermediate and highly resistant isolates was 53% for chloramphenicol. Both penicillin-resistant strains were isolated during the last 2 years of collection and came from patients of non-Norwegian ethnic background. Imported strains appeared over represented among the strains resistant to penicillin and macrolides. Only imipenem and vancomycin showed full susceptibility for all pneumococci tested. An over representation of serogroup 6 strains was apparent among the strains with intermediate susceptibility and high resistance to benzylpenicillin. It is apparent that high-level resistance has, not so far, become a difficult problem in Norway. Nevertheless, the situation requires monitoring of the resistance level, particularly in meningitis and septic patients, and certainly in patients who cntail a higher than usual possibility of acquiring pneumococci from pools of resistant strains outside Norway (visitors, immigrants and recent returness from abroad).