[Identification and typing of Pseudomonas pickettii during an episode of nosocomial outbreak]

Abstract

From January to April 1989, Pseudomonas pickettii was isolated from clinical specimens of 24 hospitalized patients at the National Taiwan University Hospital in Taipei. The source of the organism was the 0.9% NaCl solution prepared by the hospital pharmacy. A total of 39 isolates of P. pickettii were collected, including 28 from clinical specimens and 11 from 0.9% saline and distilled water during the outbreak. These microorganisms were studied by using four methods, namely, conventional biochemical method, Vitek Auto-Microbic System (Vitek AMS), gas-liquid chromatographic analysis of cellular fatty acids composition and determination of the minimum inhibitory concentrations of 10 different antimicrobial agents. By conventional biochemical method, 16 isolates were typed as biovar 1 and 23 strains were biovar 3. Strains of both biovars were recovered from clinical specimens and 0.9% saline. Vitek AMS was able to identify P. pickettii correctly, but the result of biotyping was not satisfactory. Analysis of cellular fatty acids could rapidly identify P. pickettii to the species level, but could not distinguish the different biovars. By determination of the MICs, the antibiogram could be classified into 9 patterns. Of 16 isolates of P. pickettii biovar 1, 7 (44%) belonged to pattern I, and 9 (56%) pattern II. Strains of both patterns were found in cultures of clinical specimens and 0.9% saline. Of 23 isolates of P. pickettii biovar 3, 11 (48%) belonged to pattern III, 4 (17%) pattern IV and 8 (35%) pattern V to IX. Pattern III and pattern IV were seen in isolates from clinical specimens and 0.9% saline, while pattern V to IX were only seen in isolates from clinical specimens.(ABSTRACT TRUNCATED AT 250 WORDS)