Abstract
A method for typing Pseudomonas aeruginosa using antibiotic susceptibility patterns is presented, which allows recognition of clusters of the same strain among clinical isolates from different patients, thus indicating whether cross infection has occurred. An index of similarity (the euclidean or the oblique distance), which includes all the differences of disk zone sizes among isolates, is computed and then elaborated by a clustering algorithm that successively groups all the isolates in larger clusters. The results of clustering are presented as dendrograms, whose terminal branches are pruned down to a level below which differences are casual; isolates that still appear on a common branch are considered identical. The reliability of this technique for detecting nosocomial cross infections was assessed by comparing its results with that of serotyping and pyocin typing. Only 2 of 31 (6.4%) clusters detected by multivariate analysis were not confirmed, while 4 of 33 (12.1%) clusters were recognized by serotyping and pyocin typing, but not by multivariate analysis. In at least two instances the differences in susceptibility patterns were due to cytoplasmic R factors. The routine use of antibiogram data for typing purposes should be considered an essential part of nosocomial infection control.
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References
Cross, A. S.: Evolving epidemiology ofPseudomonas aeruginosa infections. European Journal of Clinical Microbiology 1985, 44: 156–159.
Schimpf, S. C., Moody, M., Young, V. M.: Relationship of colonization withPseudomonas aeruginosa to development ofPseudomonas bacteremia in cancer patients. Antimicrobial Agents and Chemotherapy 1970, 240–244.
Bodey, G. P.: Epidemiological studies ofPseudomonas species in patients with leukemia. American Journal of Medical Sciences 1970, 260: 82–89.
Gould, I. M., Wise, R.:Pseudomonas aeruginosa clinical manifestation and management. Lancet 1985, ii: 1224–1226.
Bodey, G. P., Bolivar, R., Fainstein, V., Jadeja, I.: Infections caused byPseudomonas aeruginosa. Reviews of Infectious Diseases 1983, 5: 279–313.
National Committee for Clinical Laboratory Standards: Performance standards for antimicrobial disc susceptibility tests. National Committee for Clinical Laboratory Standards, Villanova PA, 1975.
Goldmann, D. A., Macone, A. B.: A microbiological approach to the investigation of bacterial nosocomial infection outbreaks. Infection Control 1980, 1: 391–400.
Barry, A. L., Coyle, M. B., Thornsberry, C., Gerlach, E. H., Hawkinson, R. W.: Methods of measuring zones of inhibition with the Bauer-Kirby disk susceptibility test. Journal of Clinical Microbiology 1979, 10: 885–889.
Fyfe, J. A. M., Harris, G., Govan, J. R. W.: Revised pyocin typing method forPseudomonas aeruginosa. Journal of Clinical Microbiology 1984, 20: 47–50.
Govan, J. R. W.: Pyocin typing ofPseudomonas aeruginosa. In: Bergan, T., Norris, J. R. (ed.): Methods in microbiology. Volume 10. Academic Press, London, 1978, p. 61–91.
Anderberg, R. M.: Cluster analysis for applications. Academic Press, New York, 1973, p. 99–132.
Orloci, L.: Multivariate analysis in vegetation research. W. Junk Publishers, The Hague, 1978.
Pinner, R. W., Haley, R. W., Blumenstein, B. A., Shaberg, D. R., Von Allmen, S. D., McGowan, Jr. J. E.: High cost nosocomial infections. Infection Control 1982, 3: 143–149.
Dixon, R. E.: Effect of infections on hospital care. Annals of Internal Medicine 1978, 89: 749–753.
Goldmann, D. A., Macone, A. B.: A microbiologic approach to the investigation of bacterial nosocomial infection outbreaks. Infection Control 1980, 1: 391–400.
Goldmann, D. A.: Laboratory procedures for infection control. In Lennette, E. H., Balows, A., Hausier, Jr. W. J., Truant, J. P. (ed.): Manual of clinical microbiology. American Society for Microbiology, Washington, DC, 1980, p. 939–951.
Centers for Disease Control: The Role of the microbiology Laboratory in surveillance and control of nosocomial infections. National Nosocomial Infections Study Report. Annual Summary, Atlanta 1974.
Barry, A. L., Schoenknecht, F. D., Shadomy, S.: Inter-laboratory variability of disk diffusion and agar dilution susceptibility tests with cefamandole and cephalothin. Current Microbiology 1978, 1: 277–280.
Flournoy, D. J.: Quantitative antibiograms as a potential tool for epidemiological typing. Infection Control 1982, 3: 384–387.
Aber, R. C., Mackel, D. C.: Epidemiologic typing of nosocomial microorganisms. American Journal of Medicine 1981, 70: 899–905.
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Giacca, M., Monti-Bragadin, C. Multivariate analysis of antibiograms for typingPseudomonas aeruginosa . Eur. J, Clin. Microbiol. 6, 552–558 (1987). https://doi.org/10.1007/BF02014245
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DOI: https://doi.org/10.1007/BF02014245