Antibiotic resistance in invasive Streptococcus pneumoniae isolates identified in Scotland between 1999 and 2007

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Invasive pneumococcal disease (IPD) poses a significant public health challenge.
• Monitoring antimicrobial susceptibility patterns of Streptococcus pneumoniae is crucial for effective treatment.
• The Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory collects vital data on pneumococcal isolates.

Purpose of the Study:

• To analyze antimicrobial susceptibility profiles of invasive Streptococcus pneumoniae isolates in Scotland.
• To determine resistance trends to penicillin, erythromycin, and cefotaxime between 1999 and 2007.
• To identify specific serogroups and clones associated with resistance patterns.

Main Methods:

• Retrospective analysis of 4727 invasive Streptococcus pneumoniae isolates.
• Determination of minimum inhibitory concentrations (MICs) for penicillin, erythromycin, and cefotaxime.
• Serotyping and molecular typing of resistant isolates, including identification of internationally recognized clones.

Main Results:

• Penicillin resistance remained low (0.2%), with sporadic isolates mainly from serogroup 14 (ST9) and 9 (ST156).
• Erythromycin resistance was found in 12% of isolates, predominantly serogroup 14 (ST9).
• Cefotaxime resistance was very low (0.06%). Internationally recognized clones predominated in resistant isolates.

Conclusions:

• Susceptibility to key antimicrobial agents for invasive pneumococcal disease in Scotland remained high during 1999-2007.
• Erythromycin resistance, particularly in serogroup 14, warrants continued surveillance.
• The findings support the ongoing effectiveness of first-line treatments for IPD in the studied period.