Standardizing Clinical Microbiology

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UW microbiology professors established standards for clinical testing practices that have been widely adopted throughout this country and the world. In a history of the UW microbiology department, Charles A. Evans, chairman from 1946-1970, wrote about the lack of standards that plagued the practice of clinical testing in earlier decades:

In the late forties and the fifties the quality of microbiological work in clinical laboratories in the United States was disgracefully poor. Laboratory tests were commonly performed by poorly paid workers with no scientific or technical training...Congressional hearings provided abundant evidence of the deplorable state of this aspect of medical care. Forty to fifty percent of independent laboratories and voluntary hospital laboratories in New York City failed to detect medically important bacteria in at least half of the specimens they received in a survey conducted by the City Health Department.footnote 1

Evans and others in the UW microbiology department have helped to modernize and standardize clinical testing practices and to provide quality assurance for those procedures. Evans was instrumental in launching the American Academy of Microbiology and its offshoot, the American Board of Microbiology, which certified properly qualified clinical laboratory microbiologists at the postdoctoral level, as well as the National Registry of Microbiologists which certified bachelor's and master's level personnel.

In the late 1950s, Evans recruited John Sherris to the faculty, who together with UW professors Bauer and Kirby developed standardized procedures for assessing bacterial resistance to antibiotics. The standards were adopted by the U.S. Food and Drug Administration and have had a major impact on the field of clinical microbiology.

Up to that time, a variety of tests to assess bacterial resistance had proliferated with the introduction of penicillin to clinical use. These tests were used to detect strains of bacteria that caused serious infections and that were unresponsive to penicillin or to other antibiotics. But the procedures had lacked standards for interlaboratory comparison.

Sherris notes that "as late as the early 1970s, studies on the reproducibility of tests made on the same strain by different laboratories showed serious discrepancies, and some workers felt that testing as a guide to therapy was more misleading than helpful. Poor interlaboratory reproducibility also compromised epidemiologic studies of resistance and the evaluation of new [therapeutic] agents..."footnote 2

About that time, the U.S. Food and Drug Administration's certification requirements for clinical testing materials were being reviewed in the courts as a result of a manufacturer's challenge. In the process of considering the case, the court reviewed the entire state of affairs regarding susceptibility testing.

The Court determined that the FDA not only should assure the content and reproducibility of these testing materials, but it should also require manufacturers to provide instructions for proper use to obtain reproducible results.

The FDA selected the methods developed by Kirby and Bauer and colleagues in Seattle, later the Kirby-Bauer-Sherris method, as the standard for the field. The researchers had standardized the test with respect to the bacterial sample, the medium used to culture the bacteria, criteria for interpreting results, and quality controls. At the same time, Sherris and colleague Hans Ericsson, of the Karolinska Institute, Stockholm, proposed several reference procedures, which have since been adopted in many countries.

  1. "History of the Department of Microbiology of the University of Washington: The First Twenty Years in the New School of Medicine as Viewed by the Departmental Chairman," Charles A. Evans, 1987.
  2. "Antimicrobic Susceptibility Testing: A Personal Perspective," John C. Sherris, Clinics in Laboratory Medicine, 9 (2), 191 (1989).

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