A comparative study for efficacy of Povidone Iodine in combination with Ornidazole and Metronidazole in anaerobic isolates

Background: The majority of infected wounds are polymicrobial and their treatment is complicated owing to relatively slow growth of organisms and growing resistance of anaerobic bacteria to antimicrobial agents. Hence, the present study was initiated to assess the efficacy of Povidone iodine alone and in combination with Ornidazole and Metronidazole in anaerobic isolates. Methods: Brucella blood agar plates were inoculated with suspension of anaerobic clinical isolates of Peptostreptococcus magnus, Clostridium perfringens, and Bacteroides fragilis. After solidification, 100 µL drug solutions of each antimicrobial agent were added, incubated in anaerobic conditions. Zone of inhibitions were measured after 7-9 days to determine minimum inhibitory concentration. Results: Combination of Povidone iodine 5% and Ornidazole 1% was the most effective combination in inhibiting the growth of Bacteroides fragilis and Clostridium perfringens whereas the combination of Povidone iodine 5% and Metronidazole 1% was more effective in inhibiting the growth of Peptostreptococcus magnus than Povidone iodine alone / other drug combinations. Conclusion: The present study reveals that addition of Ornidazole or Metronidazole to Povidone iodine was more effective, than Povidone iodine alone, in inhibiting the growth of all tested anaerobic bacteria namely Bacteroides fragilis, Clostridium perfringens, and Peptostreptococcus magnus.