[Effect of erythromycin on anti staphylococcal activity and dye production of Pseudomonas aeruginosa isolated from clinical materials].

Anti staphylococcal activity by Pseudomonas aeruginosa was investigated through the use of the reversed agar plate and the filter paper stamp methods. Investigation was also conducted on the dye production of different clinical isolates of Pseudomonas aeruginosa, the relationship between drug susceptibility and anti staphylococcal activity, and the influence of erythromycin on anti staphylococcal activity. Seventy four strains of Pseudomonas aeruginosa were prepared which included 20 strains from pus, 34 strains from sputum and 20 strains from urine. These were then inoculated with methicillin resistant Staphylococcus aureus (MRSA). They were then cultured for 48 hours by using the reversed agar plate and the filter paper stamp methods. Anti staphylococcal activity was observed in 16 strains from pus (80%), 19 strains from sputum (55.9%) and 8 strains from urine (40%). The Pseudomonas aeruginosa strains which have no pigment tended to show poor anti staphylococcal activity. Drug susceptibility was tested using PIPC, AMK, IPM, CFS and OFLX. The strains which showed resistance to OFLX tended to show poor anti staphylococcal activity. Erythromycin inhibited the dye production of Pseudomonas aeruginosa but exhibited no effect on anti staphylococcal activity. Consequently, these results suggest erythromycin has exhibited a previously unknown pharmacological effect, furthermore, anti staphylococcal activity was not caused by pigmentation only.