1887
Volume 2014, Issue 2
  • ISSN: 0253-8253
  • E-ISSN: 2227-0426

Abstract

There is increasing interest in the use of quantitative PCR (q-PCR) for diagnosis of infection. However, the assay remains largely unstandardized, making comparison between studies unreliable. The objective of this study was to assess accuracy of a normalized q-PCR assay for diagnosis of the infection. Seventy-six fresh gastric biopsy specimens were collected from patients undergoing upper gastrointestinal tract endoscopy and examined by rapid urease test (RUT), culture, and a commercial TaqMan q-PCR assay targeting the gene. Counts obtained from the latter assay were normalized to the human ACTB gene. A subject was considered to be infected if two or more assays were positive. The detection rates were 42.1%, 52.6%, and 78.9% by culture, RUT and q-PCR, respectively. Bacterial density ranged 0.005 to 4800 bacteria per 100 human cells. Because q-PCR showed low initial specificity (45.7%), the cutoff value for the assay was recalculated as 1 bacterium per 100 human cells, using ROC curve analysis. Accordingly, the sensitivities and specificities were 79.5% and 97.3%, respectively, for culture; 94.9% and 91.9%, respectively, for RUT; and 94.9% and 94.6%, respectively, for q-PCR. By gold standard, 39 of the dyspeptic patients (51.3%) were found to be infected. With the identified cutoff value, the q-PCR assay diagnosed infection with an accuracy slightly superior to that of RUT. However, the possibility that low counts detected only by q-PCR represent true infections warrants further investigation. Normalization of bacterial counts for standardization of q-PCR assays is recommended.

Loading

Article metrics loading...

/content/journals/10.5339/qmj.2014.19
2015-01-01
2019-08-17
Loading full text...

Full text loading...

/deliver/fulltext/qmj/2014/2/qmj.2014.19.html?itemId=/content/journals/10.5339/qmj.2014.19&mimeType=html&fmt=ahah

References

  1. [1]. Hunt   RH., , Xiao   SD., , Megraud   F., , Leon-Barua   R., , Bazzoli   F., , van der Merwe   S., , Vaz Coelho   LG., , Fock   M., , Fedail   S., , Cohen   H., , Malfertheiner   P., , Vakil   N., , Hamid   S., , Goh   KL., , Wong   BC., , Krabshuis   J., , Le Mair   A., , World Gastroenterology Organization. . Helicobacter pylori in developing countries. World Gastroenterology Organisation Global Guideline. . J Gastrointestin Liver Dis.   2011 Sep; ;20: 3 : 299– 304 .
    [Google Scholar]
  2. [2]. Bardhan   PK. . Epidemiological features of Helicobacter pylori infection in developing countries. . Clin Infect Dis.   1997 Nov; ;25: 5 : 973– 978 .
    [Google Scholar]
  3. [3]. Khedmat   H., , Karbasi-Afshar   R., , Agah   S., , Taheri   S. . Helicobacter pylori Infection in the general population: A Middle Eastern perspective. . Caspian J Intern Med.   2013 Fall; ;4: 4 : 745– 753 .
    [Google Scholar]
  4. [4]. Marshall   BJ., , Warren   JR. . Unidentified curved bacilli in the stomach of patients with gastritis and peptic ulceration. . Lancet . 1984 Jun 16; ;1: 8390 : 1311– 1315 .
    [Google Scholar]
  5. [5]. Peter   S., , Beglinger   C. . Helicobacter pylori and gastric cancer: the causal relationship. . Digestion . 2007; ;75: 1 : 25– 35 .
    [Google Scholar]
  6. [6]. Monteiro   L., , de Mascarel   A., , Sarrasqueta   AM., , Bergey   B., , Barberis   C., , Talby   P., , Roux   D., , Shouler   L., , Goldfain   D., , Lamouliatte   H., , Mégraudgraud   F. . Diagnosis of Helicobacter pylori infection: noninvasive methods compared to invasive methods and evaluation of two new tests. . Am J Gastroenterol.   2001 Feb; ;96: 2 : 353– 358 .
    [Google Scholar]
  7. [7]. Calvet   X., , Sanchez-Delgado   J., , Montserrat   A., , Lario   S., , Ramirez-Lazaro   MJ., , Quesada   M., , Casalots   A., , Suárez   D., , Campo   R., , Brullet   E., , Junquera   F., , Sanfeliu   I., , Segura   F. . Accuracy of diagnostic tests for Helicobacter pylori: a reappraisal. . Clin Infect Dis.   2009 May 15; ;  48: 10 : 1385– 1391 .
    [Google Scholar]
  8. [8]. Megraud   F., , Lehours   P. . Helicobacter pylori detection and antimicrobial susceptibility testing. . Clin Microbiol Rev.   2007 Apr; ;20: 2 : 280– 322 .
    [Google Scholar]
  9. [9]. Kobayashi   D., , Eishi   Y., , Ohkusa   T., , Ishige., , Suzuki   T., , Minami   J., , Yamada   T., , Takizawa   T., , Koike   M. . Gastric mucosal density of Helicobacter pylori estimated by real-time PCR compared with results of urea breath test and histological grading. . Med Microbiol.   2002 Apr; ;51: 4 : 305– 311 .
    [Google Scholar]
  10. [10]. Ramirez-Lazaro   MJ., , Lario   S., , Casalots   A., , Sanfeliu   E., , Boix   L., , Garcia-Iglesias   P., , Sánchez-Delgado   J., , Montserrat   A., , Bella-Cueto   MR., , Gallach   M., , Sanfeliu   I., , Segura   F., , Calvet   X. . Real-time PCR improves Helicobacter pylori detection in patients with peptic ulcer bleeding. . PLoS One.   2011; ;6: 5 : e20009 .
    [Google Scholar]
  11. [11]. Karaman   M., , Abacolu   H., , Topalak   OS., , Simek   I. . Molecular detection of Helicobacter pylori vacA and cagA genes in gastric tissue specimens of patients with peptic ulcer disease and non-ulcer dyspepsia. . Mikrobiyoloji bülteni.   2011; ;45: 1 : 11 .
    [Google Scholar]
  12. [12]. Schabereiter-Gurtner   C., , Hirschl   AM., , Dragosics   B., , Hufnagl   P., , Puz   S., , Kovách   Z., , Rotter   M., , Makristathis   A. . Novel real-time PCR assay for detection of Helicobacter pylori infection and simultaneous clarithromycin susceptibility testing of stool and biopsy specimens. . J Clin Microbiol.   2004; ;42: 10 : 4512– 4518 .
    [Google Scholar]
  13. [13]. He   Q., , Wang   J-P., , Osato   M., , Lachman   LB. . Real-time quantitative PCR for detection of Helicobacter pylori. . J clin microbiol.   2002; ;40: 10 : 3720– 3728 .
    [Google Scholar]
  14. [14]. Lascols   C., , Lamarque   D., , Costa   JM., , Copie-Bergman   C., , Le Glaunec   JM., , Deforges   L., , Soussy   CJ., , Petit   JC., , Delchier   JC., , Tankovic   J. . Fast and accurate quantitative detection of Helicobacter pylori and identification of clarithromycin resistance mutations in H. pylori isolates from gastric biopsy specimens by real-time PCR. . J Clin Microbiol.   2003 Oct; ;41: 10 : 4573– 4577 .
    [Google Scholar]
  15. [15]. Ribeiro   ML., , Ecclissato   CC., , Mattos   RG., , Mendonca   S., , Pedrazzoli   J Jr. . Quantitative real-time PCR for the clinical detection of Helicobacter pylori. . Genet Mol Biol.   2007; ;30: 2 : 431– 434 .
    [Google Scholar]
  16. [16]. Said   RM., , Cheah   PL., , Chin   SC., , Goh   KL. . Evaluation of a new biopsy urease test: Pronto Dry, for the diagnosis of Helicobacter pylori infection. . Eur J Gastroenterol Hepatol.   2004 Feb; ;16: 2 : 195– 199 .
    [Google Scholar]
  17. [17]. Al-Sulami   A., , Al-Kiat   H., , Bakker   L., , Hunoon   H. . Primary isolation and detection of Helicobacter pylori from dyspeptic patients: a simple, rapid method. . East Mediterr Health J.   2008; ;14: 2 : 268– 275 .
    [Google Scholar]
  18. [18]. Pandy   HB., , Patel   JS., , Sodagar   NR., , Singh   NR., , Salvi   PN., , Patel   SB., , Naik   KB., , Agravat   HH. . Comparison of invasive tests with serology to diagnosed Helicobacter pylori infections in symptomatic patients. . J Cell Tissue Res . 2009; ;9: 3 : 2019– 2022 .
    [Google Scholar]
  19. [19]. Kumar   A., , Imran   M., , Singh   AK., , Chandel   D., , Talwar   A. . Detection of Helicobacter pylori in gastroduodenal diseases by Real-time PCR. . J Biomed Sci and Res.   2010; ;2: 3 : 170– 178 .
    [Google Scholar]
  20. [20]. Yamamoto   Y. . PCR in diagnosis of infection: detection of bacteria in cerebrospinal fluids. . Clin Diagn Lab Immunol.   2002 May; ;9: 3 : 508– 514 .
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.5339/qmj.2014.19
Loading
/content/journals/10.5339/qmj.2014.19
Loading

Data & Media loading...

Supplementary File 1

  • Article Type: Research Article
Keyword(s): culture , Helicobacter pylori , normalization , quantitative PCR and rapid urease test
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error