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 variety of antibiotics (gentamicin, amikacin, azlocillin, cefotaxime, chloramphenicol and polymyxin B) were determined by Stoke's method at 20 degrees C, 30 degrees C, 37 degrees C and 42 degrees C. Minimum inhibitory concentrations (MIC) were determined for aminoglycosides on Mueller-Hinton agar at the above temperatures. There was a significant difference in susceptibility between 20 degrees C or 30 degrees C (most resistant), 37 degrees C (more susceptible) and 42 degrees C (most susceptible) to gentamicin and to a lesser degree to amikacin for P. maltophilia, 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.