Anti-Saccharomyces cerevisiae Antibody Does Not Differentiate Between Crohn's Disease and Intestinal Tuberculosis

Abstract

The clinical, morphological, and histological features of intestinal tuberculosis (IT) and Crohn's disease (CD) mimic so much, that it becomes difficult to differentiate between them. The sensitivity of anti-Saccharomyces cerevisiae antibody (ASCA) IgG and ASCA IgA in CD is 60%-80%, whereas the specificity is almost 90%. There are no reports of study of ASCA in patients with IT, nor has it ever been used to differentiate CD from IT. Patients with ulcerative colitis (UC; n=25), CD (n=59), and IT (n=30) and 21 healthy controls were included in this study. The location and behavior of CD were classified according to the Modified Montreal classification. Five milliliters of blood was taken from them and serum was stored at -70 degrees C. ASCA antibodies (both IgG and IgA) were estimated using commercially available ELISA kits (AESKU Diagnostics, Germany). Anti-neutrophilic cytoplasmic antibody was measured by indirect immunofluorescence test. ASCA IgA was positive in 4.7%, 28%, 33.9%, and 43.3% and ASCA IgG was positive in 4.7%, 24%, 50.8%, and 46.6% of healthy controls and patients with UC, CD, and IT, respectively. Either ASCA IgG or ASCA IgA was positive in 9.5%, 40%, 61% and 66.6% of healthy controls, UC, CD, and IT, respectively. ANCA was positive in 0%, 32%, 10.1%, and 6.6% of healthy controls, UC, CD, and IT, respectively. ASCA IgG was positive in a significantly higher number of patients with CD (P<0.0001) and IT (P<0.0001) in comparison to healthy controls. ASCA IgA was positive in a significantly higher number of patients with UC (P<0.04), CD (P<0.013), and IT (P<0.006) in comparison to healthy controls. In comparisons between diseases, ASCA IgG was positive in significantly more patients with CD (P<0.001) and IT (P<0.001) in comparison to UC. There was no significant difference in ASCA IgA (33.9% vs. 43.3%), ASCA IgG (50.86% vs. 46.6%), or ANCA (10.7%, 7.4%) in patients with CD and IT, respectively. There was no correlation between ASCA and duration, location and behavior of CD, and IT. We conclude that ASCA IgG and ASCA IgA do not help to differentiate between IT and CD.

Diagnosis of Crohn’s disease in India where tuberculosis is widely prevalent

“…In the previous study, we found that (1) serological markers were not significantly different between CD and GITB; and (2) prevalence of positive ASCA was much lower in patients with CD than the reported incidence from Western countries [28] . A recent study by another centre in India showed that ASCA was not helpful in differentiating CD from GITB [31] . The present study confirms these results.…”

Crohn’s Disease in India: A Multicenter Study from a Country Where Tuberculosis Is Endemic

“…Thus, all our patients had been treated with ATT without definite microbiological demonstration of bacilli from the involved tissue, and they represent mis-diagnosed cases of CD that will often happen in a tuberculosis-endemic population. Although differentiation from abdominal/ intestinal TB was not the aim of our study, two of our centers had evaluated the role of anti-Saccharomyces cerevisiae antibodies in differentiating between the two, with negative results [16,36]. The differences between the two diseases have been extensively reviewed recently [37] and are summarized in Table 2.…”

“…Despite this, doubts persisted as to whether this was true CD in view of the widespread endemicity of intestinal tuberculosis in India, so much so, that a diagnosis of CD was met with derision [12]. However, in the past few years there has been a growing realization that, despite the high prevalence of intestinal tuberculosis, CD does occur in India [13][14][15][16]. This has been attributed to increasing awareness and availability of diagnostic facilities, coupled with improved sanitation, as is being seen in the rest of Asia.…”

“…This has been attributed to increasing awareness and availability of diagnostic facilities, coupled with improved sanitation, as is being seen in the rest of Asia. Despite this, only a few reports, involving a few patients, have been published from India in recent years, and those, too, have usually been limited to a select group of patients with ileo-cecal or colonic CD [14][15][16] or a subgroup of patients presenting with obscure gastrointestinal (GI) bleeding [17].…”

Indian Society of Gastroenterology consensus statements on Crohn’s disease in India

“…Ghoshal et al found that 8 of 16 patients with intestinal tuberculosis and 10 of 16 patients with CD had ASCA antibodies [42]. In a study from New Delhi including 59 patients with CD and 30 patients with intestinal tuberculosis, ASCA was positive in 61 % of CD patients compared to 66 % of intestinal tuberculosis patients [43]. Another study found ASCA positivity in 9 of 30 CD patients compared to 3 of 30 patients with intestinal tuberculosis, a difference that was not statistically significant [34].…”