Concept of segmentation in nosocomial epidemiology: epidemiological relation among antimicrobial-resistant isolates of Pseudomonas aeruginosa.

Typing studies on 271 clinical strains of Pseudomonas aeruginosa isolated from the University Teaching Hospital were conducted to obtain their serotypes, antimicrobial susceptibility patterns and plasmid profiles. These strain typing data were arranged through multivariate statistical analysis by computation to classify individual strains. Plots in the scatter diagrams obtained from both principal component analysis and quantification theory type III expressed the clinical strains of P. aeruginosa with various degrees of antimicrobial resistance. Epidemiological relation among these clinical strains was analysed in those scatter diagrams by segmentation, in combination with their epidemiological information (date and place of isolation, type of specimen, etc.). The results showed that the serotype E strains both with high-level resistance to gentamicin and with a plasmid of 3.9 x 10(6) dalton, and the strains resistant to more than five antimicrobial agents, were colonized and localized each in certain clinical wards for inpatients. It was suggested that segmentation analysis could be of practical use in the management of nosocomial infection control against P. aeruginosa with antimicrobial resistance.