Evaluation of Real Time PCR, ELISA and Direct Strip Tests for Detection of Helicobacter pylori Infection in Patients with Gastrointestinal Illnesses

Abstract

Helicobacter pylori (H. pylori) infection is very common worldwide. The infection causes chronic gastritis which significantly increases the risk of developing gastric or duodenal ulcer, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. This study was undertaken for the detection of cagA gene in biopsy specimens from patients with gastrointestinal diseases by real time PCR test, in addition to serological detection of anti H. pylori IgG and IgM antibodies by ELISA and direct strip tests. A total of 50 antral biopsy and serum specimens were subjected to real time PCR test conducted together with ELISA test for serological diagnosis. Stomach cancer comprised the lowest frequency by admission diagnosis, 1(2%). PCR test was positive in 45 (90%) of study group. Specimens from patients with gastric ulcer, gastritis & dudenitis, stomach cancer, and multiple polyps recorded 100% positive PCR test. Out of total, ELISA-IgM was positive in 16 (32%) of study group, whereas IgG was positive in 23 (46%) of study group. Direct strip test was positive in 18 (36%) of study group. Our study suggested that stomach cancer is unusually rare in Iraq, despite the high prevalence rate of H. pylori infection in this developing country. ELISA-IgM and IgG and direct strip tests showed a low sensitivity and specificity for the diagnosis of H. pylori infection in a group of Iraqi patients. Polymerase chain reaction is highly specific and may be more sensitive than other biopsy-based diagnostic techniques. Although PCR is a time consuming and expensive procedure with need for highly trained staff performing it, our study demonstrated that using PCR methods for detection of H. pylori have a high diagnostic accuracy rate. Further research is needed to study virulence markers and genetic heterogeneity of H. pylori in patients with gastrointestinal illnesses.