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The effect of pH on the multiplication of a pseudomonad in chlorhexidine and cetrimide
Abstract:
Pseudomonas cepacia (Ps. multivorans) can become adapted to a 1 in 30 dilution of Savlon hospital concentrate in distilled water, and can multiply in it. The organism so adapted did not survive in Savlon of the same strength made with hard tap water (pH 7.2). This effect was due to the difference of pH between the two solutions. At the pH of the distilled water solution (pH 6.0) Savlon also showed reduced activity against Proteus vulgaris, but activity against Ps. aeruginosa was not affected.
Insights
Pseudomonas cepacia adapted to a diluted disinfectant in distilled water survived, but not in hard tap water due to pH differences. This pH-dependent disinfectant activity impacts bacterial survival and growth.
Area of Science:
- Microbiology
- Environmental Science
- Disinfectant Efficacy
Background:
- Pseudomonas cepacia (now multivorans) is a resilient bacterium.
- Hospital disinfectants like Savlon are crucial for infection control.
- Environmental factors, such as water hardness and pH, can influence disinfectant effectiveness.
Purpose of the Study:
- To investigate the adaptability of Pseudomonas cepacia to a specific Savlon dilution.
- To determine the survival of adapted bacteria in disinfectants prepared with different water types.
- To elucidate the role of pH in modulating disinfectant activity against various bacterial species.
Main Methods:
- Bacterial adaptation experiments using Pseudomonas cepacia in Savlon (1:30 dilution) in distilled water.
- Survival assays of adapted bacteria in Savlon prepared with hard tap water (pH 7.2).
- Comparative testing of Savlon efficacy against Proteus vulgaris and Pseudomonas aeruginosa at different pH levels.
Main Results:
- Pseudomonas cepacia adapted and multiplied in Savlon (1:30) in distilled water (pH 6.0).
- Adapted bacteria failed to survive in the same Savlon dilution prepared with hard tap water (pH 7.2).
- Reduced Savlon activity was observed against Proteus vulgaris at pH 6.0, but not against Pseudomonas aeruginosa.
Conclusions:
- The pH of the water used to dilute Savlon significantly impacts its efficacy and bacterial survival.
- Pseudomonas cepacia exhibits adaptability to disinfectants, but this adaptation is constrained by environmental pH.
- Disinfectant efficacy is a complex interplay between the disinfectant formulation, target organism, and water chemistry.