Serotype distribution of penicillin-resistant pneumococci and their susceptibilities to seven antimicrobial agents

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Streptococcus pneumoniae is a leading cause of bacterial infections worldwide.
• Antimicrobial resistance, particularly to penicillin, poses a significant threat to effective treatment.
• Understanding the prevalence and patterns of resistance is crucial for public health.

Purpose of the Study:

• To determine the susceptibility patterns of clinical Streptococcus pneumoniae isolates to various antibiotics.
• To investigate the association between penicillin resistance and specific serotypes of Streptococcus pneumoniae.

Main Methods:

• Serotyping of 229 clinical isolates of Streptococcus pneumoniae.
• Antimicrobial susceptibility testing against penicillin G, ampicillin, mezlocillin, cefazolin, erythromycin, clindamycin, chloramphenicol, and sulfamethoxazole-trimethoprim.

Main Results:

• 21.0% of isolates showed intermediate resistance and 7.4% showed resistance to penicillin G.
• Penicillin-resistant strains exhibited higher minimal inhibitory concentrations for ampicillin, mezlocillin, and cefazolin.
• Resistance to erythromycin and clindamycin was rare (1.3% and 0.9%).
• 8.7% of isolates were resistant to sulfamethoxazole-trimethoprim; all remained susceptible to chloramphenicol.
• Penicillin resistance was linked to 13 serotypes, with serotypes 14, 19F, 19A, and 23F being highly prevalent and frequently penicillin-resistant.

Conclusions:

• A significant proportion of clinical Streptococcus pneumoniae isolates exhibit penicillin resistance.
• Specific serotypes are disproportionately associated with penicillin resistance, highlighting potential targets for surveillance and intervention.
• Continued monitoring of antimicrobial susceptibility patterns is essential for guiding treatment strategies against Streptococcus pneumoniae infections.