Susceptibility of Pseudomonas and Staphylococcus wound isolates to topical antimicrobial agents: a 10-year review and clinical evaluation.

A 10-year review of Ps. aeruginosa and Staph. aureus susceptibility to various topical agents is presented. Susceptibility testing was performed using the agar well diffusion (AWD) method. A reduction in microbial growth to numbers less than 10(5) per gram of tissue in the wound, measured by quantitative biopsy, was compared with predicted susceptibility test results. In this measurement of clinical efficacy, silver sulphadiazine and mafenide acetate compared most favourably with AWD results, 83 per cent and 82 per cent respectively. However, nitrofurazone only reduced bacterial counts to less than 10(5) per gram 42 per cent of the time when an inhibition zone was present. Hydrogen peroxide solution (1 per cent) was 100 per cent effective by the AWD test, but no relationship to clinical efficacy could be shown. Minimal inhibitory concentration (MIC) data for gentamicin sulphate was compared to AWD and showed a positive relationship of greater than 80 per cent for both organisms. The AWD test has been a useful aid in the decision-making process for the choice of topical agent by providing data which eliminates agents inappropriate for use.