PubMed1980
Disk diffusion susceptibility tests were performed on 180 recent clinical isolates of Pseudomonas aeruginosa. Minimal inhibitory concentration values were determined at the same time by a broth microdilution method. All isolates were sensitive to colistin (< 4 migrogram/ml), but resistant to ampicillin (greater than or equal to 16 microgram/ml), cephalothin (greater than or equal to 64 microgram/ml), and nitrofurantoin (> microgram/ml). More than 90% of the isolates were sensitive to gentamicin (median, less than or equal to 0.25 microgram/ml), tobramycin (median, less than or equal to 0.25 microgram/ml), and amikacin (median, less than or equal to 1.0 microgram/ml) and more than 70% were sensitive to carbenicillin (median, 64 microgram/ml). When the resistant and intermediate categories were combined, over 90% of the isolates were resistant to tetracycline (median 16 microgram/ml), chloramphenicol (median, > 32 microgram/ml), kanamycin (median, 16 microgram/ml), and trimethoprim-sulfonamide combiantion (median, 4 microgram/ml; 76 microgram/ml). Differences between the disk diffusion and microdilution methods in distinguishing resistant isolates of P aeruginosa from sensitive isolates were minor. Complete agreement between the two methods was obtained in 87.0% of the observations.