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Utility of Gomori methenamine silver stains in bronchoalveolar lavage specimens

S S Raab1, J C Cheville, K Bottles

  • 1Department of Pathology, University of Iowa, Iowa City.

Insights

Gomori methenamine silver (GMS) stain shows 100% sensitivity for detecting Pneumocystis and fungi in bronchoalveolar lavage (BAL) samples. This diagnostic method is particularly valuable for immunosuppressed patients, including those with acquired immunodeficiency syndrome (AIDS).

Area of Science:

  • Medical diagnostics
  • Infectious disease pathology
  • Pulmonology

Background:

  • Bronchoalveolar lavage (BAL) with Gomori methenamine silver (GMS) stain is a standard method for identifying Pneumocystis and fungal infections in immunocompromised individuals.
  • Previous studies questioned the superior sensitivity of GMS stains compared to conventional cytologic stains, especially in patients with acquired immunodeficiency syndrome (AIDS).

Purpose of the Study:

  • To evaluate the diagnostic utility and sensitivity of GMS stains in detecting Pneumocystis and fungal organisms in bronchoalveolar lavage (BAL) samples within a specific laboratory setting.
  • To correlate GMS stain results with patient risk factors and compare its sensitivity against conventional stains.

Main Methods:

  • Retrospective review of 243 BAL samples from 188 patients.
  • Calculation of sensitivity for GMS stain, Papanicolaou stain, and Diff-Quik stain for Pneumocystis and fungi detection.
  • Correlation analysis using stepwise logistic regression to identify risk factors associated with GMS positivity.
  • Cost analysis of the GMS stain.

Main Results:

  • GMS stain demonstrated 100% sensitivity for detecting both Pneumocystis and fungi.
  • Conventional stains showed lower sensitivity: Papanicolaou (79% for Pneumocystis, 88% for fungi) and Diff-Quik (68% for Pneumocystis, 88% for fungi). Combined conventional stains reached 79% for Pneumocystis and 100% for fungi.
  • Pneumocystis positivity by GMS stain significantly correlated with a history of AIDS or AIDS risk factors (P < 0.0001).
  • Fungal positivity by GMS stain correlated with prior positive BAL fungal results (P = 0.02).

Conclusions:

  • GMS stain is a highly sensitive and effective diagnostic tool for Pneumocystis and fungal infections in BAL samples.
  • The GMS stain's utility is strongly supported, particularly in identifying Pneumocystis in patients with AIDS or related risk factors.
  • The study highlights the diagnostic value of GMS stains, justifying its continued use in clinical practice for immunocompromised patients.

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