Comparison of immunohistochemical and modified Giemsa stains for demonstration of Helicobacter pylori infection in an African population.
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.pylori antibody, 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.Pylori seems quite prevalent.


METHODS
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.pylori using both modified Giemsa and immunohisto chemical staining techniques.


RESULTS
Twenty-seven cases of H.pylori were 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.


CONCLUSIONS
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.
Wabinga
H R
HR
Department of Pathology, Faculty of Medicine Makerere University, PO Box 7072 Kampala, Uganda.
D000293:Adolescent; D000328:Adult; D000349:Africa; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001399:Azure Stains; D005260:Female; D005756:Gastritis / Q000145:classification / Q000209:etiology; D016481:Helicobacter Infections / Q000150:complications / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D013270:Stomach / Q000382:microbiology / Q000473:pathology
D000900:Anti-Bacterial Agents; D001399:Azure Stains