The Thai Journal of Pharmaceutical Sciences


Objective: Pneumococcal disease is a severe invasive infection causing morbidity and death, so the appropriate antimicrobials are greatly important. We aimed to determine the minimum inhibitory concentration (MIC) of penicillin, cefotaxime and ceftriaxone against S. pneumoniae. Methods: The clinical isolates were obtained from patients with invasive pneumococcal disease admitted to Phramongkutklao Hospital, Thailand over a period of 10 years between 2006 and 2015. The in vitro antimicrobial susceptibility testing of antibiotics including penicillin, ceftriaxone and cefotaxime against S. pneumoniae isolates were determined by E-test. The MIC range, MIC50, and MIC90 (μg/ml) and percentage of susceptible isolates were recorded. Results: Forty clinical isolates were collected, the MIC range, MIC50 and MIC90 for penicillin were: ≤0.016-1.5 μg/ml, 0.25 μg/ml and 1 μg/ml, respectively. Only 35% of them were penicillin susceptible strains. Even our studied S. pneumoniae isolates demonstrated lower trends of MICs to cefotaxime than to ceftriaxone but the MIC50/90 for cefotaxime and ceftriaxone were equal to 0.19/0.5 μg/ml, whereas the same MIC range for cefotaxime and ceftriaxone was ≤0.016-0.5 μg/ml. Conclusions: Penicillin G may no longer be an appropriate empirical pneumococcal meningitis treatment, although ceftriaxone and cefotaxime remained good activity as first-line agents for community-acquired meningitis due to S. pneumoniae. However, the non-susceptible third-generation cephalosporin strains need to be closely monitored in Thailand.


Faculty of Pharmaceutical Sciences, Chulalongkorn University

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