Activities of antipseudomonal agents against clinical isolates of Pseudomonas aeruginosa

Abstract

Using clinically isolated 114 strains of Pseudomonas aeruginosa that were collected from April to October 1994, activity of antipseudomonal agents against these organisms was determined using the method of liquid microdilution. In addition, antimicrobial activities of the agents were graded according to serological groups of organisms. The results of this study are summarized as follows. 1. Many strains of P. aeruginosa were isolated mainly from sputum, pus and urine. 2. Serological group G organisms of sputum origin, group I of pus and bile origin, and group E of urine origin were isolated most frequently. 3. The most powerful antipseudomonal agent was cefclidin. Its MIC50 and MIC90 were 0.78 and 6.25 micrograms/ml, respectively. The second most powerful agent was ciprofloxacin whose MIC50 and MIC90 were 0.39 and 12.5 micrograms/ml, respectively. 4. The proportions of resistant strains ranged from 0.9% for cefclidin to 40.4% for ofloxacin. The antipseudomonal agents to which 30% or more of strains were resistant were cefpirome, gentamicin and ofloxacin. 5. Cefclidin showed the most powerful activity against strains that were resistant to ceftazidime, imipenem, gentamicin and ofloxacin. Its MIC90 against all strains resistant to ceftazidime, gentamicin and ofloxacin was 6.25 micrograms/ml. The MIC90 of cefclidin and tobramycin against imipenem-resistant strains was 3.13 micrograms/ml. 6. Group E organisms were found among strains resistant to ceftazidime, gentamicin and ofloxacin at high rates, but no group E strains were found among imipenem-resistant organisms. 7. Agents with highest activities by serological group of organisms were cefclidin against group A, tobramycin and ciprofloxacin against group B, imipenem against group E, ciprofloxacin against group G, and cefclidin and ciprofloxacin against group I.(ABSTRACT TRUNCATED AT 250 WORDS)