Article Text

PDF
Diagnosis of conjunctivitis in primary care: comparison of two different culture procedures
  1. E Tellegen1,
  2. G ter Riet1,2,
  3. J H Sloos3,
  4. H C P M van Weert1
  1. 1
    Academic Medical Center, Department of General Practice, University of Amsterdam, Amsterdam, The Netherlands
  2. 2
    Horten Centre, University of Zurich, Zurich, Switzerland
  3. 3
    Medical Center Alkmaar, Laboratory for Medical Microbiology, Alkmaar, The Netherlands
  1. Correspondence to Dr E Tellegen, Academic Medical Center, Department of General Practice, University of Amsterdam, Meibergdreef 9, Amsterdam 1100 DD, The Netherlands; e.tellegen{at}wanadoo.nl

Abstract

Background: In general practice, infectious conjunctivitis is a common and mostly (64%) self-limiting disorder. In case of an aberrant course or severe symptoms, a general practitioner may take a culture. Direct inoculation is considered the reference standard, but usually a swab is sent to a laboratory.

Objectives: To compare the diagnostic performance of the swab, transported by surface mail with direct inoculation.

Methods: 19 general practitioners took two samples of the conjunctiva from 88 patients with symptoms suggestive of infectious conjunctivitis by rolling a cotton swab across the conjunctiva of the lower fornix. One swab was used to inoculate three agar plates directly, while the other was sent in a Stuart medium to the laboratory and inoculated at the time of arrival. The numbers of positive cultures of both methods were compared.

Results: A pathogen was found in 31 of 88 samples (35% (95% CI 26 to 46)). Surprisingly, the number of positive cultures was higher for the Stuart medium (27/88) than for direct inoculation (23/88). The difference was 4.5% (90% CI 0 to 12, p = 0.388; one-sided McNemar test for paired proportions). In five of the 19 samples that were positive in both tests, the cultured pathogens were different.

Conclusions: The Stuart medium detected more bacteria than direct inoculation. The lower 90% CI, testing non-inferiority at p = 0.05, indicates that it is unlikely that the Stuart medium misses any positive cultures compared with direct inoculation.

Statistics from Altmetric.com

Footnotes

  • Competing interests None.

  • Patient consent Obtained.

  • Provenance and peer review not commissioned; externally peer reviewed

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.