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Five-year analysis of antimicrobial susceptibility of the Streptococcus milleri group
A Limia1, M L Jiménez, T Alarcón
1Department of Microbiology, Hospital Universitario de la Princesa, Madrid, Spain.
Abstract:
Susceptibility to 17 antibiotics was studied in 180 strains of the Streptococcus milleri group (88 Streptococcus anginosus, 63 Streptococcus constellatus, and 29 Streptococcus intermedius) isolated over a 5-year period. Minimum inhibitory concentrations of penicillin were in the intermediate range for 5.6% of the strains. Resistance to erythromycin and clindamycin was found in 17.1% and 16.6% of the isolates, respectively. A steady increase in the susceptibility to ciprofloxacin was observed over the study period. Imipenem was the most active beta-lactam agent tested. Glycopeptide antibiotics showed excellent activity. Only slight differences between the three species were found in terms of antibiotic susceptibility. Intermediate resistance to penicillin is appearing among the Streptococcus milleri group in our area; consequently, care must be taken when choosing a macrolide for the management of infections caused by these microorganisms.
Insights
Antibiotic resistance is increasing in Streptococcus milleri group bacteria. Penicillin resistance is emerging, and macrolide choice requires careful consideration for effective infection management.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- The Streptococcus milleri group comprises key human pathogens.
- Understanding their antibiotic susceptibility is crucial for clinical management.
- Emerging resistance patterns necessitate ongoing surveillance.
Purpose of the Study:
- To assess the antibiotic susceptibility profiles of Streptococcus milleri group strains.
- To identify trends in antimicrobial resistance over a five-year period.
- To evaluate the activity of various antibiotic classes against these bacteria.
Main Methods:
- Antimicrobial susceptibility testing was performed on 180 Streptococcus milleri group isolates.
- Minimum inhibitory concentrations (MICs) were determined for 17 different antibiotics.
- Isolates included Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius.
- Data were analyzed over a five-year collection period.
Main Results:
- Intermediate penicillin resistance was observed in 5.6% of strains.
- Resistance rates for erythromycin and clindamycin were 17.1% and 16.6%, respectively.
- Increasing susceptibility to ciprofloxacin was noted.
- Imipenem demonstrated potent activity among beta-lactam agents.
- Glycopeptide antibiotics exhibited excellent efficacy.
- Minimal species-specific differences in susceptibility were found.
Conclusions:
- Emergence of intermediate penicillin resistance in Streptococcus milleri group is a concern.
- Macrolide antibiotic selection for infections caused by these bacteria requires caution.
- Continued monitoring of antimicrobial resistance patterns is essential.