RESUMEN
Objective: In-vitro determination of antimicrobial activities of five different fixed dose combination drugs (FDC). Material and methods: Five antibiotic combination tablets [Cefadroxil plus Clavulanic acid (500:125 mg), Cefuroxime plus Clavulanic acid (500 : 125 mg), Cefixime plus Clavulanic acid (200 : 125 mg), Cefixime plus Ofloxacin (200 : 200 mg) and Cefixime plus Azithromycin (200 : 500 mg)] were tested for antimicrobial action against different microorganisms after their successful incubation for 18 hours at 37°C. Broth dilution or agar dilution methods were used to evaluate susceptibility of microorganisms. Results: Minimum inhibitory concentration (MIC) of Cefadroxil in combination with clavulanic acid reduced by 25%, 29%, 85% and 50%, against S. aureus, K. pneumonia, H. influenzae and S. pneumoniae respectively. No reduction was seen in MIC of Cefuroxime against S. aureus, K. pneumonia, H. influenzae, E. coli or S. pneumoniae after addition of Clavulanic acid. MIC of Cefixime against S. pneumoniae reduced from 0.2 to 0.14 when combined with Clavulanic acid. MIC of Ofloxacin against K. pneumoniae, E.coli and S. pneumoniae reduced by 82%, 50% and 85% respectively in combination with Cefixime. MIC of Cefixime against E.coli, S. typhi and S. pneumoniae reduced by 95%, 90% and 40% respectively in combination with Ofloxacin. MIC of Cefixime against S. typhi and S. pneumoniae reduced by 33.33% and 60% respectively with addition of Azithromycin. MIC of Azithromycin against S. typhi reduced by 70% after addition of Cefixime. Conclusion: Combination of Cefixime and Ofloxacin improves susceptibility of E. coli and S. pneumoniae. Addition of Azithromycin or Ofloxacin improves susceptibility of S. typhi against Cefixime. MIC of Azithromycin also improves with addition of Cefixime. Addition of Clavulanic acid improves antimicrobial action of Cefixime against S. pneumoniae and Cefadroxil against S. aureus, K. pneumonia, H influenza and S. pneumonia.