Combination therapy of antibiotics can be used against multi drug resistant bacteria. In vitro investigation of two antibiotics combinations regimens were used against multi drug resistant local isolates of Pseudomonas aeruginosa that isolated from chronic otitis media patients to determine the usability of combination therapy for the treatment.
The first attempt of combination therapy regimen was tested for synergy between MIC of Rifampicin 4µg/ml with MICs of Tri-methoprim 50µg/ml, Cephlexin 50µg/ml, Tetracyclin 45µg/ml, Gentamicin 4µg/ml, and Erythromycin 40µg/ml, respectively in nutrient broth medium, the results yielded synergistic action in the combination therapy of Rifampicin and Erythromycin, confirmed spectrophotometrically. The second attempt of combination therapy examined against the same isolates on nutrient agar medium between MIC of Ciprofloxacin 20µg/ml and MICs of Rifampicin 4µg/ml, Gentamicin 4µg/ml, Streptomicin 4µg/ml, Tobramicin 3µg/ml respectively, the results were exhibited full synergistic bactericidal activity that took place for four combinations therapy with MIC of Ciprofloxacin in combination with the MICs of other antibiotics.