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[Penicillin resistance in Streptococcus pneumoniae strains]
1Hacettepe Universitesi Tip Fakültesi Mikrobiyoloji Anabilim Dali.
Abstract:
In this study a total of 87 Streptococcus pneumoniae strains were tested for their susceptibility to penicillin with disk diffusion method by using 5 micrograms methicillin disks. In 68 strains susceptibility to penicillin was also determined by using agar dilution method performed in Mueller-Hinton agar supplemented with 5% sheep blood. Of 63 adult isolates tested with disk-diffusion method 35 strains (55.6%) were susceptible to penicillin, 24 strains (38.1%) had low level resistance and 4 strains (6.3%) had high-level resistance to penicillin. Of 24 S. pneumoniae isolates recovered from children 5 (20.8%) were penicillin susceptible, while 11 (45.8%) had low level resistance and 8 (33.4%) had high level resistance to penicillin. These values were 40 (45.9%), 35 (40.3%) and 12 (13.8%) in total isolates respectively. Of 44 isolates in which MIC values of penicillin were determined by agar dilution method, 34 strains (77.3%) were penicillin susceptible and 10 strains (22.7%) had low level resistance while none of these strains had high level resistance to penicillin. Of 24 children isolates tested with agar dilution method 11 strains (45.8%) were susceptible to penicillin, 8 strains (33.4%) showed low level resistance and 5 strains (20.8%) showed high level resistance to penicillin. For total of 68 isolates these values were 45 (66.1%), 18 (26.4%) and 5 (7.3%) respectively. These findings indicate the need to perform antibiotic susceptibility testing of all pneumococcal isolates to avoid therapeutic failure.
Insights
Penicillin resistance in Streptococcus pneumoniae is a growing concern, with significant proportions of both adult and pediatric isolates showing resistance. Antibiotic susceptibility testing is crucial for effective treatment and avoiding therapeutic failure.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Context:
- Streptococcus pneumoniae is a leading cause of bacterial infections worldwide.
- Penicillin resistance in S. pneumoniae poses a significant challenge to public health.
- Disk diffusion and agar dilution methods are standard techniques for assessing antibiotic susceptibility.
Purpose:
- To evaluate the susceptibility of Streptococcus pneumoniae isolates to penicillin using both disk diffusion and agar dilution methods.
- To compare the resistance patterns observed in adult and pediatric isolates.
- To highlight the importance of routine antibiotic susceptibility testing for pneumococcal infections.
Summary:
- A total of 87 Streptococcus pneumoniae strains were tested for penicillin susceptibility.
- Disk diffusion revealed varying resistance levels in adult (6.3% high-level resistance) and pediatric (33.4% high-level resistance) isolates.
- Agar dilution showed lower high-level resistance rates (0% in adults, 20.8% in children) but confirmed significant penicillin resistance.
Impact:
- Findings underscore the need for routine antibiotic susceptibility testing of all pneumococcal isolates.
- Accurate susceptibility data is essential to guide appropriate antibiotic selection and prevent therapeutic failure.
- This study contributes to understanding the epidemiology of penicillin resistance in S. pneumoniae.