EFFECT OF TEMPERATURE ON ANTIMICROBIAL SUSCEPTIBILITIES OF PSEUDOMONAS SPECIES ISOLATED FROM DRINKING-WATER

The susceptibility of 20 strains of Pseudomonas species isolated from drinking waters (4 P. aeruginosa, 7 P. fluorescens, 5 P. stutzeri, 1 P . maltophilia, 1 P. cepacia, 1 P. putida and 1 P. pickettii) to a vari ety of antibiotics (gentamicin, amikacin, azlocillin, cefotaxime, chlo ramphenicol and polymyxin B) were determined by Stoke's method at 20-d egrees-C, 30-degrees-C, 37-degrees-C and 42-degrees-C. Minimum inhibit ory concentrations (MIC) were determined for aminoglycosides on Muelle r-Hinton agar at the above temperatures. There was a significant diffe rence in susceptibility between 20-degrees-C or 30-degrees-C (most res istant), 37-degrees-C (more susceptible) and 42-degrees-C (most suscep tible) to gentamicin and to a lesser degree to amikacin for P. maltoph ilia, P. cepacia and most strains of P. fluorescens. The P. aeruginosa , P. stutzeri, P. putida and P. pickettii strains showed no difference in susceptibility at 20-degrees-C, 30-degrees-C, 37-degrees-C and 42- degrees-C. The need for standardized conditions with special regard to temperature when antibiotic susceptibility tests are performed for P. maltophilia, P. cepacia and P. fluorescens strains is stressed.