A Computerized Long-Term Follow-Up of Antibiotic Sensitivity Pattern for a Hospital Region
A laboratory test request and reporting system has been in use in the Central University Hospital of Tampere (1238 beds) since 1969 as the initial stage of a hospital information system. The system has been operative throughout this time also for microbiology. The sensitivity determination has been done all these years by the so-called PDM method of the Biodisk company. The method has a specially designed medium that is quality controlled in the factory against the standardized antibiotic containing 6 mm paper discs sold by the firm. After strictly controlled incubation times etc. the diameter of the inhibition zone for each antibiotic is measured by a caliper and the results recorded in the computer data file. Biodisk provides the users with regression lines for every single antibiotic that gives the relationship of the inhibition zòne (mm) to the corresponding MIC values for the bacteria. The regression lines are kept in the computer and permit the calculation of the MIC- values when needed. Usually, however, the results are converted for the benefit of the clinician into SIR groups. The individual results may be collected into a file for multiresistant bacteria. The regression lines mentioned are changed from time to time for long-term storage, however, the data files will keep only the millimetre of the zone diameters. This makes it possible to follow over the course of time the changes that take place in the sensitivity patterns of the different antibiotics.