Helicobacter pylori stool antigen test
http://www.100md.com
《美国医学杂志》
1 SSK Bakirkoy Maternity and Children's Training Hospital, Department of Pediatric Gastroenterology, Istanbul, Turkey
2 Department of Pediatrics, Istanbul, Turkey
3 Cerrahpasa Faculty of Medicine, Istanbul, Turkey
4 Department of Microbiology, Istanbul, Turkey
5 Department of Pathology, Istanbul, Turkey
Abstract
Objective: Helicobacter pylori ( H.pylori ) infection is usually acquired in early childhood. Invasive techniques used for diagnosis of H.pylori infection require endoscopic examination which is expensive and inconvenient and may cause complications. The aim of this study was to evaluate the performance of a new noninvasive diagnostic method, stool antigen test for H.pylori in untreated children with recurrent abdominal pain. Methods: Eighty children (35 female, 45 male) who have undergone upper gastrointestinal endoscopy due to recurrent abdominal pain were included in the study. The H.pylori stool antigen test (HpSA) is based on a sandwich enzyme immunoassay with antigen detection. HpSA sensitivity, specificity, and positive and negative predictive values were determined with reference to the results of both histology and rapid urease test as a gold standard ( H. pylori status). Results: While 49 of the 80 children (61%) tested were positive for H.pylori according to the results of both histology and rapid urease test, 28 children had negative H.pylori status. Among those 49 children, 48 were found to be positive by HpSA. Of 28 patients with negative H.pylori status, 28 were H.pylori -negative also in the stool test. The sensitivity, specificity, and positive and negative predictive values of HpSA were found to be 98%, 100%, 100%, and 96.5%, respectively. Conclusion: These findings have demonstrated that HpSA as a relatively simple, inexpensive and time saving noninvasive test is a reliable method for detection of H.pylori infections in children.
Keywords: Recurrent abdominal pain; Helicobacter pylori, diagnosis, Helicobacter pylori stool antigen test, HpSA.
Helicobacter pylori ( H.pylori ) infection has been linked to gastritis, duodenal ulcer, gastric cancer, and gastric lymphomas. It is now generally agreed that H. pylori infections are acquired during childhood or adolescence in developing as well as developed countries.[1]
Since H.pylori infection is associated with many clinical conditions in childhood, it requires to be diagnosed during this period. There are two categories of diagnostic methods used for detection of H.pylori: invasive tests such as histology, rapid urease test and culture, and noninvasive tests such as 13subC-urea breath test (UBT) and serology.[2] A noninvasive and practical diagnostic tool for detection of H.pylori infection is even more desirable in pediatrics, because upper gastrointestinal endoscopies in young children are usually performed in intubation anesthesia or conscious sedation.[3]
Serological tests and UBT have certain disadvantages. While serological tests lack in sufficient reliability in children and adolescence, UBT is expensive, causes administrative difficulties in young children and is not available in all countries although it is as reliable as invasive methods.[4] Because many studies support the hypothesis of a fecal-oral route of infection, and because H.pylori has been detected in the stool, interest has focused on the diagnostic detection of H.pylori antigens in stool samples.[3] H.pylori stool antigen test (HpSA) is an enzyme immunoassay (EIA) to detect H.pylori antigen in stool specimen.[5] This test was approved in USA in 1998 for both diagnosis and monitoring the response to treatment of H.pylori infection in adult patients.[4] HpSA was found to have very reliable results particularly in adult patients as a noninvasive method.[2],[6],[7],[8] Similar results have also been obtained in recent studies conducted in children.[1],[3],[4],[9]
The aim of this study was to compare invasive methods with a noninvasive method which detects H.pylori antigen in stool specimens for the diagnosis of H.pylori infection in untreated Turkish children with recurrent abdominal pain.
Material and methods
Eighty children admitted to the Department of Pediatric Gastroenterology due to recurrent abdominal pain and underwent upper gastrointestinal endoscopy were included in the study. The mean age of the children (mean ± SD) was 8.9 ± 3.6 yr (age range: 2 to 15 year). Thirty-five of them were girls and 45 were boys. Recurrent abdominal pain was defined as occurrence of abdominal pain limiting school or other activities at regular intervals for more than 3 months in at least 1 year. Those who received antibiotic treatment, H2-blockers or proton pump inhibitors due to any reason for six weeks before undergoing endoscopic examination were excluded from the study. The study was performed according to the Declaration of Helsinki, and all parents gave informed consent for the participation of their child in the study.
Biopsy-based methods
Gastroscopy was performed in all patients. During endoscopy, three biopsy specimens were collected in the antrum of the stomach of each patient: two for histology and one for rapid urease test. The rapid urease test (CLO test; Delta West, Perth, WA, Australia) was considered as positive for H.pylori if a color change from orange to pinkish was seen within 24 hours. In the histological test, the presence of H.pylori was based on the identification of curved rods in the hematoxylin and eosin, or modified Giemsa-stained sections.
Helicobacter pylori status
A patient was considered as H.pylori -infected if both histology and rapid urease tests were positive, and as H.pylori -negative when both tests gave negative results. Patients who had only one positive test on rapid urease test or histology were considered to be of indeterminate status.
HpSA
A fresh stool sample with approximately the size of a peanut was collected and stored at -20oC for analysis as described previously. HpSA (Premier Platinum HpSA, Meridian Diagnostics, Cincinnati, OH) was performed according to the manufacturer's recommendations without knowledge of the H.pylori status. The test is based on a sandwich EIA with antigen detection. This is a qualitative test with a polyclonal rabbit anti- H.pylori antibody adsorbed to microwells as capture antibody. First, 100 μl of a diluted stool sample (10 μl stool in 0.5 ml sample diluent) and thereafter, peroxidase-conjugated polyclonal antibody solution were added to the wells and incubated for 1 hour at room temperature. Unbound material was removed by washing. After addition of a substrate solution, H.pylori antigen could be detected by a color change. A stop solution was added and the absorbance was read at 450 nm by a spectrophotometer. The results were interpreted as follows: OD450<0.140 was negative, OD450>0.160 was positive, and the value in between was equivocal. Equivocal results should be repeated.
Statistical analysis
The sensitivity, specificity, and positive and negative predictive values of HpSA were calculated against the H.pylori status for the results of HpSA.
Results
Based on the proposed H.pylori status, 49 patients were infected, 28 were not infected, and 3 were of indeterminate status. In 48 of the 49 patients, H.pylori antigen could be detected in stool. On the other hand, 28 children were negative by HpSA. There was only one false-negative result, and none of the cases were false-positive. None of the stool samples was read as equivocal in the present study. The sensitivity, specificity, and positive and negative predictive values of HpSA were found to be 98%, 100%, 100%, and 96.5%, respectively table1.
Discussion
Detection of H. pylori infection in childhood today mostly depends on the endoscopic biopsy of the gastric tissue which is an invasive method performed for rapid urease test, histology, and culture.[10] These methods have been recognized as gold standard. In pediatric patients, however, invasive procedures have major disadvantages such as risk of anesthesia, discomfort, and terrifying the patients and their parents. For this reason, common use of those procedures in children is limited.[1],[3] Therefore, a noninvasive, practical, and sensitive diagnostic test for the detection of H.pylori infection is desirable.[3]
The most common noninvasive tests are serology and UBT.[1],[4] Serology is based on the detection of specific IgG and IgA antibodies by using the ELISA method in patients infected by H. pylori.[11] It is not solely used in diagnosis of the infection but particularly used for epidemiological or screening studies.[12] Serological methods are not reliable in children and fail in the diagnosis and in monitoring the success of anti- H.pylori therapy .[13] Up to the present, UBT is the favorite diagnostic tool in children for the diagnosis of H.pylori infection because it avoids upper gastrointestinal endoscopy.[14],[15],[16] The accuracy of noninvasive UBT in diagnosing H.pylori infection has also been evaluated in children with reference to histology and culture. [17],[18],[19],[20],[21] UBT is based on the stable isotope technique and combines the advantages of noninvasiveness, excellent sensitivity and specificity. [14],[15],[16] However, there are some disadvantages of the test including its requirement of a mass spectrometer device which is very expensive and its wrong results due to lack of cooperation of young children for performing the inhalation and exhalation exercises.[1],[20] Besides, this test is available only in a very few centers in Turkey.
HpSA is a newly developed noninvasive EIA. It is not time-consuming and is cheaper than the UBT. The analytical technique of the immunoassay in stool samples can be performed easily in any laboratory. Feces can be obtained easily, even in newborn children. Spot samples of the stool are sufficient; homogenization of the stool is not required.[3] This new test utilizes a polyclonal anti- H.pylori capture antibody that is adsorbed to microwells and shows good performance characteristics.[5] HpSA has been found to have comparable diagnostic value for detection of H. pylori infection and for monitoring the response to treatment in adult patients. [22],[23],[24],[25]
In the present study, results of HpSA were compared with H.pylori status. Positive H.pylori status and positive HpSA results were consistent in 48 patients, while negative H.pylori status and negative HpSA results were consistent in all patients. We observed one false-negative stool test result, but there was no false-positive test result. Therefore, the sensitivity, specificity, and positive and negative predictive values of HpSA in untreated children were 98%, 100%, 100%, and 96,5%, respectively. Other investigators have reported similar high sensitivities (86.9-100%) and specificities (92-100%) of HpSA in untreated children. Positive and negative predictive values have been found similarly high in these studies.[1],[3],[9],[26],[27],[28],[29],[30]
Besides, it has been claimed that HpSA can be used for monitoring treatment success and that successful eradication of H.pylori can be confirmed after treatment.[26] The accuracy of HpSA has been confirmed in children, and this may be the optimal test to confirm the success of eradication therapy.[1],[4],[27] HpSA has been found to be a useful method for post-treatment eradication testing of H.pylori infection in children.[27] However, some investigators have reported that results of HpSA reveal an unsatisfactory sensitivity after treatment.[26],[31]
In conclusion, HpSA as a noninvasive test, does not have the disadvantages seen in UBT and is as reliable as invasive tests. HpSA is suitable to use particularly in developing countries like ours. Detection of H.pylori antigens using HpSA shows a high sensitivity and specificity and might be useful for noninvasive diagnosis of H.pylori infection in children. HpSA may be useful particularly in selection of the cases requiring endoscopic examination, in monitoring the response to treatment and in epidemiological studies.
References
1. Ni YH, Lin JT, Huang SF, Yang JC, Chang MH. Accurate diagnosis of Helicobacter pylori infection by stool antigen test and 6 other currently available tests in children. J Pediatr 2000; 136: 823-827.
2. Makristathis A, Pasching E, Schtze K, Wimmer M, Rotter ML, Hirschl AM. Detection of Helicobacter pylori in stool specimens by PCR and antigen enzyme immunoassay. J Clin Microbiol 1998; 36: 2772-2774.
3. Braden B, Posselt H, Ahrens P, Kitt R. New immunoassay in stool provides an accurate noninvasiv diagnostic method for H pylori screaning in children. Pediatrics 2000; 106: 115-117.
4. Oderda G, Rapa A, Ronchi B, et al. Detection of Helicobacter pylori in stool specimens by noninvasive antigen enzyme immunoassay in children: multicentre Italian study. BMJ 2000; 320: 347-348.
5. Kim PS, Lee J, Pai SH et al. Detection of H.pylori antigen in stool by enzyme immunoassay. Yonsei Med J 2002; 43: 7-13.
6. Perri F, Clemente R, Pastore M, et al. The 13C-urea breath test as a predictor of intragastric bacterial load and severity of Helicobacter pylori gastritis. Scand J Clin Lab Invest 1998; 58: 19-27.
7. Vaira D, Malfertheiner P, Megraud F et al. Diagnosis of helicobacter pylori infection with a new noninvasive antigen based assay. Lancet 1999; 354: 30-33.
8. Braden B, Teuber G, Dietrich CF, Caspary WF, Lembcke B. New fecal antigen test detects Helicobacter pylori infection and eradication:a prospective clinical evaluation. Br Med J 2000; 320: 148-149.
9. Constantopoulos N, Rüssmann H, Tasch C et al. Evaluation of the H.pylori stool antigen test for detection of H.pylori infection in children. Am J Gastroenterol 2001; 96: 677-683.
10. Bourke B, Jones NL, Sherman PM. Helicobacter pylori infection and peptic ulcer disease in children. Pediatr Infect Dis J 1996; 15: 1-13.
11. Gosciniak G, Klakockar J, Przondo-Mordarska A, Mauff G. Helicobacter pylori antibodies in sera of children suffering from chronic abdominal pain. Zentralbl Bakteriol 1993; 280: 214-220.
12. Bujanover Y, Reif S, Yahav J. Helicobacter pylori and peptic disease in the pediatric patient. Pediatr Clin North Am 1996; 43: 213-234.
13. Cutler AF, Prasad VM. Long-term follow-up Helicobacter pylori serology after successful eradication. Am J Gastroenterol 1996; 91: 85-88.
14. Graham DY, Evans DJ, Alpert LC et al. C. pylori detected non-invasively by the [13]C-urea breath test. Lancet 1987; 1: 1174-1177.
15. Eggers RH, Kulp A, Tegeler R et al. A methodological analysis of the 13C-urea breath test for detection Helicobacter pylori infections: high sensitivity and specificity within 30 min using 75 mg of 13C-urea. Eur J Gastroenterol Hepatol 1990; 2: 437-444.
16. Braden B, Duan LP, Caspary WF, Lembcke B. More convenient 13C-urea breath test modifications still meet the criteria for valid diagnosis of Helicabacter pylori infection. Z Gastroenterol 1994; 32: 198-202.
17. Koletzko S, Haisch M, Seeboth I et al. Isotope selective nondispersive infrared spectrometry for detection of Helicobacter pylori infection with 13C-urea breath test. Lancet 1995; 345: 961-962.
18. Kindermann A, Demmelmaier H, Koletzko B, Krauss-Etschmann S, Wiebecke B, Koletzko S. Influence of age on the 13C-urea breath test results in children. J Pediatr Gastroenterol Nutr 2000; 30: 85-91.
19. Vincent P, Michaud L, de Lasalle ME, Benon B, Truck D, Gottrand F. 13C-urea breath test and gastric mucosal colonization by Helicobacter pylori in children: quantitative relation usefulness for diagnosis of infection. Helicobacter 1994; 4: 233-237.
20. Vandenplas Y, Blecker U, Devreker T et al. Contribution of the 13C-urea breath test to the detection of Helicobacter pylori gastritis in children. Pediatrics 1992; 90: 608-11.
21. Delvin EE, Brazier JL, Deslandres C Alvarez F, Russo P, Seidmann E. Accuracy of the 13C-urea breath test in diagnosing Helicobacter pylori gastritis in pediatric patients. J Pediatr Gastroenterol Nutr 1999; 28: 59-62.
22. Andersen LP, Pedersen KG, Thoreson AC et al. An analysis of seven different methods to diagnose Helicobacter pylori infections. Scand J Gastroenterol 1998; 33: 24-30.
23. Chang MC, Wu MS, Wang HH, Wang HP, Lin JT. Helicobacter pylori stool antigen (HpSA) test A simple, accurate and noninvasive test for detection of Helicobacter pylori infection. Hepatogastroenterology 1999; 46: 299-302.
24. Agha-Amiri K, Mainz D, Peitz U et al. Evaluation of an enzyme immunoassay for detecting Helicobacter pylori antigens in human stool samples. Z Gastroenterol 1999; 37: 1145-1149.
25. Trevisani L, Santori S, Galvani FRMR et al. Evaluation of a new enzyme immunoassay for detecting Helicobacter pylori in feces: A prospective pilot study. Am J Gastroenterol 1999; 94: 1830-1833.
26. Arents NL, van Zwet AA, Thijs JC, de Jong A, Pool MO, Kleibeuker JH. The accuracy of Helicobacter pylori stool antigen test in diagnosis H.pylori in treated and untreated patients. Eur J Gastroenterol Hepatol 2001; 13: 383-386.
27. Gosciniak G, Mordarska AP, Iwanczak B, Blitek A. Helicobacter pylori antigens in stool specimens of gastritis children before and after treatment. J Pediatr Gastroenterol Nutr 2003; 36: 376-380.
28. Husson MO, Rolland C, Gottrand F et al. Evaluation of a Helicobacter pylori stool antigen test for the diagnosis and follow-up of infections in children. Eur J Clin Microbiol Infect Dis 2000; 19: 787-789.
29. van Doorn OJ, Bosman DK, van't Hoff BW, Taminiau JA, ten Kate FJ, van der Ende A. Helicobacter pylori Stool Antigen test: a reliable non-invasive test for the diagnosis of Helicobacter pylori infection in children. Eur J Gastroenterol Hepatol 2001; 13: 1061-1065.
30. de Carvalho Costa Cardinali L, Rocha GA, Rocha AM et al. Evaluation of [13C]urea breath test and Helicobacter pylori stool antigen test for diagnosis of H. pylori infection in children from a developing country. J Clin Microbiol 2003; 41: 3334-3335.
31. Caselli M, Zaffoni E, Trevisani L et al. Diagnosis of Helicobacter pylori infection by HpSA test. Lancet 1999; 354: 1209-1210.(Gulcan E Mahir, Varol Ayd)
2 Department of Pediatrics, Istanbul, Turkey
3 Cerrahpasa Faculty of Medicine, Istanbul, Turkey
4 Department of Microbiology, Istanbul, Turkey
5 Department of Pathology, Istanbul, Turkey
Abstract
Objective: Helicobacter pylori ( H.pylori ) infection is usually acquired in early childhood. Invasive techniques used for diagnosis of H.pylori infection require endoscopic examination which is expensive and inconvenient and may cause complications. The aim of this study was to evaluate the performance of a new noninvasive diagnostic method, stool antigen test for H.pylori in untreated children with recurrent abdominal pain. Methods: Eighty children (35 female, 45 male) who have undergone upper gastrointestinal endoscopy due to recurrent abdominal pain were included in the study. The H.pylori stool antigen test (HpSA) is based on a sandwich enzyme immunoassay with antigen detection. HpSA sensitivity, specificity, and positive and negative predictive values were determined with reference to the results of both histology and rapid urease test as a gold standard ( H. pylori status). Results: While 49 of the 80 children (61%) tested were positive for H.pylori according to the results of both histology and rapid urease test, 28 children had negative H.pylori status. Among those 49 children, 48 were found to be positive by HpSA. Of 28 patients with negative H.pylori status, 28 were H.pylori -negative also in the stool test. The sensitivity, specificity, and positive and negative predictive values of HpSA were found to be 98%, 100%, 100%, and 96.5%, respectively. Conclusion: These findings have demonstrated that HpSA as a relatively simple, inexpensive and time saving noninvasive test is a reliable method for detection of H.pylori infections in children.
Keywords: Recurrent abdominal pain; Helicobacter pylori, diagnosis, Helicobacter pylori stool antigen test, HpSA.
Helicobacter pylori ( H.pylori ) infection has been linked to gastritis, duodenal ulcer, gastric cancer, and gastric lymphomas. It is now generally agreed that H. pylori infections are acquired during childhood or adolescence in developing as well as developed countries.[1]
Since H.pylori infection is associated with many clinical conditions in childhood, it requires to be diagnosed during this period. There are two categories of diagnostic methods used for detection of H.pylori: invasive tests such as histology, rapid urease test and culture, and noninvasive tests such as 13subC-urea breath test (UBT) and serology.[2] A noninvasive and practical diagnostic tool for detection of H.pylori infection is even more desirable in pediatrics, because upper gastrointestinal endoscopies in young children are usually performed in intubation anesthesia or conscious sedation.[3]
Serological tests and UBT have certain disadvantages. While serological tests lack in sufficient reliability in children and adolescence, UBT is expensive, causes administrative difficulties in young children and is not available in all countries although it is as reliable as invasive methods.[4] Because many studies support the hypothesis of a fecal-oral route of infection, and because H.pylori has been detected in the stool, interest has focused on the diagnostic detection of H.pylori antigens in stool samples.[3] H.pylori stool antigen test (HpSA) is an enzyme immunoassay (EIA) to detect H.pylori antigen in stool specimen.[5] This test was approved in USA in 1998 for both diagnosis and monitoring the response to treatment of H.pylori infection in adult patients.[4] HpSA was found to have very reliable results particularly in adult patients as a noninvasive method.[2],[6],[7],[8] Similar results have also been obtained in recent studies conducted in children.[1],[3],[4],[9]
The aim of this study was to compare invasive methods with a noninvasive method which detects H.pylori antigen in stool specimens for the diagnosis of H.pylori infection in untreated Turkish children with recurrent abdominal pain.
Material and methods
Eighty children admitted to the Department of Pediatric Gastroenterology due to recurrent abdominal pain and underwent upper gastrointestinal endoscopy were included in the study. The mean age of the children (mean ± SD) was 8.9 ± 3.6 yr (age range: 2 to 15 year). Thirty-five of them were girls and 45 were boys. Recurrent abdominal pain was defined as occurrence of abdominal pain limiting school or other activities at regular intervals for more than 3 months in at least 1 year. Those who received antibiotic treatment, H2-blockers or proton pump inhibitors due to any reason for six weeks before undergoing endoscopic examination were excluded from the study. The study was performed according to the Declaration of Helsinki, and all parents gave informed consent for the participation of their child in the study.
Biopsy-based methods
Gastroscopy was performed in all patients. During endoscopy, three biopsy specimens were collected in the antrum of the stomach of each patient: two for histology and one for rapid urease test. The rapid urease test (CLO test; Delta West, Perth, WA, Australia) was considered as positive for H.pylori if a color change from orange to pinkish was seen within 24 hours. In the histological test, the presence of H.pylori was based on the identification of curved rods in the hematoxylin and eosin, or modified Giemsa-stained sections.
Helicobacter pylori status
A patient was considered as H.pylori -infected if both histology and rapid urease tests were positive, and as H.pylori -negative when both tests gave negative results. Patients who had only one positive test on rapid urease test or histology were considered to be of indeterminate status.
HpSA
A fresh stool sample with approximately the size of a peanut was collected and stored at -20oC for analysis as described previously. HpSA (Premier Platinum HpSA, Meridian Diagnostics, Cincinnati, OH) was performed according to the manufacturer's recommendations without knowledge of the H.pylori status. The test is based on a sandwich EIA with antigen detection. This is a qualitative test with a polyclonal rabbit anti- H.pylori antibody adsorbed to microwells as capture antibody. First, 100 μl of a diluted stool sample (10 μl stool in 0.5 ml sample diluent) and thereafter, peroxidase-conjugated polyclonal antibody solution were added to the wells and incubated for 1 hour at room temperature. Unbound material was removed by washing. After addition of a substrate solution, H.pylori antigen could be detected by a color change. A stop solution was added and the absorbance was read at 450 nm by a spectrophotometer. The results were interpreted as follows: OD450<0.140 was negative, OD450>0.160 was positive, and the value in between was equivocal. Equivocal results should be repeated.
Statistical analysis
The sensitivity, specificity, and positive and negative predictive values of HpSA were calculated against the H.pylori status for the results of HpSA.
Results
Based on the proposed H.pylori status, 49 patients were infected, 28 were not infected, and 3 were of indeterminate status. In 48 of the 49 patients, H.pylori antigen could be detected in stool. On the other hand, 28 children were negative by HpSA. There was only one false-negative result, and none of the cases were false-positive. None of the stool samples was read as equivocal in the present study. The sensitivity, specificity, and positive and negative predictive values of HpSA were found to be 98%, 100%, 100%, and 96.5%, respectively table1.
Discussion
Detection of H. pylori infection in childhood today mostly depends on the endoscopic biopsy of the gastric tissue which is an invasive method performed for rapid urease test, histology, and culture.[10] These methods have been recognized as gold standard. In pediatric patients, however, invasive procedures have major disadvantages such as risk of anesthesia, discomfort, and terrifying the patients and their parents. For this reason, common use of those procedures in children is limited.[1],[3] Therefore, a noninvasive, practical, and sensitive diagnostic test for the detection of H.pylori infection is desirable.[3]
The most common noninvasive tests are serology and UBT.[1],[4] Serology is based on the detection of specific IgG and IgA antibodies by using the ELISA method in patients infected by H. pylori.[11] It is not solely used in diagnosis of the infection but particularly used for epidemiological or screening studies.[12] Serological methods are not reliable in children and fail in the diagnosis and in monitoring the success of anti- H.pylori therapy .[13] Up to the present, UBT is the favorite diagnostic tool in children for the diagnosis of H.pylori infection because it avoids upper gastrointestinal endoscopy.[14],[15],[16] The accuracy of noninvasive UBT in diagnosing H.pylori infection has also been evaluated in children with reference to histology and culture. [17],[18],[19],[20],[21] UBT is based on the stable isotope technique and combines the advantages of noninvasiveness, excellent sensitivity and specificity. [14],[15],[16] However, there are some disadvantages of the test including its requirement of a mass spectrometer device which is very expensive and its wrong results due to lack of cooperation of young children for performing the inhalation and exhalation exercises.[1],[20] Besides, this test is available only in a very few centers in Turkey.
HpSA is a newly developed noninvasive EIA. It is not time-consuming and is cheaper than the UBT. The analytical technique of the immunoassay in stool samples can be performed easily in any laboratory. Feces can be obtained easily, even in newborn children. Spot samples of the stool are sufficient; homogenization of the stool is not required.[3] This new test utilizes a polyclonal anti- H.pylori capture antibody that is adsorbed to microwells and shows good performance characteristics.[5] HpSA has been found to have comparable diagnostic value for detection of H. pylori infection and for monitoring the response to treatment in adult patients. [22],[23],[24],[25]
In the present study, results of HpSA were compared with H.pylori status. Positive H.pylori status and positive HpSA results were consistent in 48 patients, while negative H.pylori status and negative HpSA results were consistent in all patients. We observed one false-negative stool test result, but there was no false-positive test result. Therefore, the sensitivity, specificity, and positive and negative predictive values of HpSA in untreated children were 98%, 100%, 100%, and 96,5%, respectively. Other investigators have reported similar high sensitivities (86.9-100%) and specificities (92-100%) of HpSA in untreated children. Positive and negative predictive values have been found similarly high in these studies.[1],[3],[9],[26],[27],[28],[29],[30]
Besides, it has been claimed that HpSA can be used for monitoring treatment success and that successful eradication of H.pylori can be confirmed after treatment.[26] The accuracy of HpSA has been confirmed in children, and this may be the optimal test to confirm the success of eradication therapy.[1],[4],[27] HpSA has been found to be a useful method for post-treatment eradication testing of H.pylori infection in children.[27] However, some investigators have reported that results of HpSA reveal an unsatisfactory sensitivity after treatment.[26],[31]
In conclusion, HpSA as a noninvasive test, does not have the disadvantages seen in UBT and is as reliable as invasive tests. HpSA is suitable to use particularly in developing countries like ours. Detection of H.pylori antigens using HpSA shows a high sensitivity and specificity and might be useful for noninvasive diagnosis of H.pylori infection in children. HpSA may be useful particularly in selection of the cases requiring endoscopic examination, in monitoring the response to treatment and in epidemiological studies.
References
1. Ni YH, Lin JT, Huang SF, Yang JC, Chang MH. Accurate diagnosis of Helicobacter pylori infection by stool antigen test and 6 other currently available tests in children. J Pediatr 2000; 136: 823-827.
2. Makristathis A, Pasching E, Schtze K, Wimmer M, Rotter ML, Hirschl AM. Detection of Helicobacter pylori in stool specimens by PCR and antigen enzyme immunoassay. J Clin Microbiol 1998; 36: 2772-2774.
3. Braden B, Posselt H, Ahrens P, Kitt R. New immunoassay in stool provides an accurate noninvasiv diagnostic method for H pylori screaning in children. Pediatrics 2000; 106: 115-117.
4. Oderda G, Rapa A, Ronchi B, et al. Detection of Helicobacter pylori in stool specimens by noninvasive antigen enzyme immunoassay in children: multicentre Italian study. BMJ 2000; 320: 347-348.
5. Kim PS, Lee J, Pai SH et al. Detection of H.pylori antigen in stool by enzyme immunoassay. Yonsei Med J 2002; 43: 7-13.
6. Perri F, Clemente R, Pastore M, et al. The 13C-urea breath test as a predictor of intragastric bacterial load and severity of Helicobacter pylori gastritis. Scand J Clin Lab Invest 1998; 58: 19-27.
7. Vaira D, Malfertheiner P, Megraud F et al. Diagnosis of helicobacter pylori infection with a new noninvasive antigen based assay. Lancet 1999; 354: 30-33.
8. Braden B, Teuber G, Dietrich CF, Caspary WF, Lembcke B. New fecal antigen test detects Helicobacter pylori infection and eradication:a prospective clinical evaluation. Br Med J 2000; 320: 148-149.
9. Constantopoulos N, Rüssmann H, Tasch C et al. Evaluation of the H.pylori stool antigen test for detection of H.pylori infection in children. Am J Gastroenterol 2001; 96: 677-683.
10. Bourke B, Jones NL, Sherman PM. Helicobacter pylori infection and peptic ulcer disease in children. Pediatr Infect Dis J 1996; 15: 1-13.
11. Gosciniak G, Klakockar J, Przondo-Mordarska A, Mauff G. Helicobacter pylori antibodies in sera of children suffering from chronic abdominal pain. Zentralbl Bakteriol 1993; 280: 214-220.
12. Bujanover Y, Reif S, Yahav J. Helicobacter pylori and peptic disease in the pediatric patient. Pediatr Clin North Am 1996; 43: 213-234.
13. Cutler AF, Prasad VM. Long-term follow-up Helicobacter pylori serology after successful eradication. Am J Gastroenterol 1996; 91: 85-88.
14. Graham DY, Evans DJ, Alpert LC et al. C. pylori detected non-invasively by the [13]C-urea breath test. Lancet 1987; 1: 1174-1177.
15. Eggers RH, Kulp A, Tegeler R et al. A methodological analysis of the 13C-urea breath test for detection Helicobacter pylori infections: high sensitivity and specificity within 30 min using 75 mg of 13C-urea. Eur J Gastroenterol Hepatol 1990; 2: 437-444.
16. Braden B, Duan LP, Caspary WF, Lembcke B. More convenient 13C-urea breath test modifications still meet the criteria for valid diagnosis of Helicabacter pylori infection. Z Gastroenterol 1994; 32: 198-202.
17. Koletzko S, Haisch M, Seeboth I et al. Isotope selective nondispersive infrared spectrometry for detection of Helicobacter pylori infection with 13C-urea breath test. Lancet 1995; 345: 961-962.
18. Kindermann A, Demmelmaier H, Koletzko B, Krauss-Etschmann S, Wiebecke B, Koletzko S. Influence of age on the 13C-urea breath test results in children. J Pediatr Gastroenterol Nutr 2000; 30: 85-91.
19. Vincent P, Michaud L, de Lasalle ME, Benon B, Truck D, Gottrand F. 13C-urea breath test and gastric mucosal colonization by Helicobacter pylori in children: quantitative relation usefulness for diagnosis of infection. Helicobacter 1994; 4: 233-237.
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