Beaumont Hospital and Royal College of Surgeons in Ireland, Dublin 9, Ireland
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Abstract |
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Introduction |
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Interpretative reporting of microbiology results entails the addition of a comment to the report, giving the likely significance of the organism(s) isolated and, where necessary, specific advice on therapy. The use of interpretative comments appended to microbiology reports has been shown to allow clinicians to make informed decisions based on such reports.2
This study assessed the impact of these practices in the reporting of positive culture results in hospital in-patients.
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Materials and methods |
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Limited antimicrobial susceptibilities are released only if the isolate, specimen type and clinical details suggest a need for therapy. The pager and telephone extension numbers of the CMT are provided on all reports. Susceptibility results can be obtained around the clock by contacting the CMT member on-call, who can access the laboratory computer system via a modem link.
The responses to positive urine, sputum and wound/soft-tissue culture results for 169 in-patients were assessed. Reports on patients in the intensive care unit, who are reviewed daily by the CMT, were excluded from this study as were other patients seen on consultation. Positive reports from normally sterile and/or deep tissue sites were also excluded, as the CMT discussed these results directly with the relevant clinician via telephone contact and/or ward visits.
Patient charts and nursing notes were reviewed within 24 h of the report being issued and again 5 days later by two of the authors (H.A.A. and D.S.). Indications for sending the specimen were divided into symptomatic (i.e. specimen taken in response to a presumed infective episode) and asymptomatic (i.e. no precipitating infective episode). The response to the report was considered appropriate if the report prompted the clinician to contact the CMT or if antibiotic therapy was started or altered according to the susceptibilities given in patients with a clinical indication for therapy. If no therapy was given in patients without a clinical indication the response was also considered appropriate. The appropriateness of antibiotic therapy was independently assessed, in the light of the hospital antibiotic policy, by two of the authors (R.C. and E.M.).
Proportions were analysed using the 2 test, with Fisher's exact test where a cell value was less than or equal to five. Statistical analysis and power calculations were carried out using Epi-Info (CDC, Atlanta, GA, USA, version 6.04).
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Results and discussion |
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The type, and examples, of interpretative comments used are shown in Table II. Clinicians were significantly more likely to contact the CMT in response to reports in which non-antibiotic therapeutic advice was given (RR 2.72, 95% CI 1.156.48, P = 0.03), or where the isolate was multiply resistant (RR 3.48, 95% CI 1.876.48, P < 0.001), compared with other comments.
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Of the 137 reports where the CMT was not contacted therapy was started or altered in 30 (22%), but was considered appropriate in only seven (22%). In 21 cases no action was taken in response to the report, despite an indication to do so. In 19 of these cases there was an indication to stop or narrow antibiotic therapy and in two cases an indication to start antibiotics was ignored, despite release of susceptibilities in the latter cases.
Antibiotic susceptibilities were released on 29 (17%) reports with a mean of three appropriate susceptibilities released per report. Therapy was significantly more likely to be started or altered in response to the 29 reports in which susceptibilities were released (12; 41%) compared with the 140 where susceptibilities were withheld (31; 22%) (RR 2.07, 95% CI 1.083.97, P = 0.03). This may reflect a tendency to consider reports that include susceptibilities as warranting treatment, regardless of clinical indications. The therapy started in response to reports (n = 43) was considered appropriate in six of 12 (50%) where susceptibilities were released, compared with 15 of 31 (48%) where susceptibilities were suppressed (RR 1.05, 95% CI 0.42.74, P = 0.9). The lack of impact of susceptibility release on the appropriateness of therapy may be due to the small number of reports in the study that had susceptibilities released (29 of 169). The study had an 80% power to detect a 1.67-fold difference in appropriate therapy between the two groups. This may also reflect the use of hospital antibiotic policy as a basis of assessment, and thus a narrow definition of appropriate therapy. Susceptibilities were released on reports only where there was an apparent indication for therapy, which would be expected to increase the appropriate prescribing in this group. Further restriction of susceptibility release, encouraging more discussion with the CMT before starting therapy, and more directed interpretative comments, such as advice on the most appropriate antibiotic(s) to use, may thus be indicated.
There is clearly a need for education of clinicians regarding indications for sending specimens and applying results to patient management. Susceptibilities can safely be withheld on non-critical microbiology reports. Combined with interpretative reporting, this promotes appropriate responses to such reports and discussion with the CMT, when therapeutic intervention is being considered. This approach is facilitated in our institution by a computerized reporting system, so that the time commitment from the CMT is not significantly increased. It allows us to affect the management of patients other than those who would routinely be seen on consultation. As such it forms an important part of the overall infection/antibiotic management programme in our institution.
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Notes |
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References |
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2 . Barnes, M. P. (1980). Influence of laboratory reports on prescribing of antimicrobials for urinary tract infection. Journal of Clinical Pathology 33, 4813.[Abstract]
3 . Spencely, M., Parker, M. J., Dewar, R. A. D. & Miller, D. L. (1979). The clinical value of microbiological laboratory investigations. Journal of Infection 1, 2336.[ISI]
4 . Ackerman, V. P., Pritchard, R. C., Obbink, D. J., Bradbury, R. & Lee, A. (1979). Consumer survey on microbiology reports. Lancet 313, 199202.
5 . Doern, G. V., Vatour, R., Gaudet, M. & Levy, B. (1994). Clinical impact of rapid in vitro susceptibility testing and bacterial identification. Journal of Clinical Microbiology 32, 175762.[Abstract]
6 . Trenholme, G. M., Kaplan, R. L., Karakusis, P. H., Stine, T., Fuhrer, J., Landau, W. et al. (1989). Clinical impact of rapid identification and susceptibility testing of bacterial blood culture isolates. Journal of Clinical Microbiology 27, 13425.[ISI][Medline]
Received 27 April 1999; returned 9 August 1999; revised 18 October 1999; accepted 6 December 1999