Comparison of immunohistochemical and modified Giemsa stains for demonstration of Helicobacter pyloriinfection in an African population.

H. R. Wabinga
Department of Pathology, Faculty of Medicine
Makerere University, P. O. Box 7072 Kampala, Uganda.

ABSTRACT
Background: Modified Giemsa staining has been favoured by many researchers because it is easy to perform but, like many other stains, demonstration of the bacteria depends on its morphology. It has been arged in some research circles that some of the organisms in the gastric mucosa may not be true H.pylori.Immunohistochemical techniques have been developed and make use of anti H.pyloriantibody, which reacts, with somatic antigens of the whole bacteria and have been found to correlate well with the presence of the bacteria.

Objective: To ascertain the efficacy of modified Giemsa stain in an African setting where H.Pyloriseems quite prevalent. Study Design:A laboratory-based study of two diagnostic tests in which modified Giema stain was compared with immunohistochemistry.

Methods:A total of 48 consecutive autopsy cases with no upper gastro intestinal diseases had their gastric mucosa stained for demonstration of H.pyloriusing both modified Giemsa and immunohisto chemical staining techniques.

Results:Twenty-seven cases of H.pyloriwere demonstrated by both techniques and 14 cases were not identified by the two staining methods. In 2 cases immunostain could not demonstrate the bacteria but they were identified with modified Giemsa stain while in 5 cases the bacteria were identified by immunostain but not with modified Giemsa stain.

The sensitivity of modified Giemsa stain was 85% (CI 66.5-98.8) while the specificity was 89% (CI 60.4 – 97.8). The positive predictive value of modified Giemsa stain was 93% CI 75 – 98.8%) while the negative predictive value was 74% (CI 48.6 – 89.9). The kappa statistic comparing the 2 stains was 0.69 (p value 0.00001) giving a good agreement between the two tests.

Conclusion: With the above results the modified Giemsa stain, which is readily available in most African laboratories, is recommenced for diagnosis of H.pylori, a prevalent infection in Africa.

Key words: H.pylori, modified Giemsa, immunohistochemical stains.
CI – Confidence Interval