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A short presentation for the different laboratory techniques used in diagnosing Helicobacter Pylori infection. A special focus is given for the diagnostic performance of every test.
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Laboratory Diagnosis of
H. Pylori Infection
Ola H. Elgaddar MD, PhD, CPHQ, LSSGB
Lecturer of Chemical Pathology
Alexandria University
Prevalence of H. pylori infection
The Helicobacter Foundation, 2014
Gram –ve Bacteria
Colonizes 50% of the
world population
Virulent strains may
cause gastritis, ulcers,
adenocarcinoma & gastric
mucosa-associated
lymphoid tissue (MALT)
lymphoma
Class I carcinogen
(WHO).
Formichella et al. Clin Vaccine Immunol 2013; 20: 1703-10
Diagnosis of H. Pylori
INVASIVE NON
INVASIVE
Histopathology
Rapid Urease Test
Culture
PCR
Urea Breath Test
Stool Ag
Serology
Diagnostic Performance
Denise et. al. Nature Reviews Nephrology 2014; 10: 215–25.
Non – Invasive Tests
1) Urea (14C) Breath Test
Non – Invasive Tests 1) Urea (14C) Breath Test
95% Sensitivity, 100% Specificity,
100% PPV, 96 % NPV
Ideal for monitoring therapeutic outcomes
Patients not on PPI for 1 week
Petrovic et.al. Hell J Nucl Med 2011; 14: 21–4.
Non – Invasive Tests 2) Stool Monoclonal Ag
Performance differs
according to reagents
88% Sensitivity, 98% Specificity,
88% PPV, 98 % NPV
FDA approved for therapeutic monitoring
Confirm eradication after 4-8W. of Rx
Not affected by PPIs
Calvet et. al. Helicobacter 2010; 15: 201–5.
Non – Invasive Tests 3) Serology (IgG / AgA)
Either Abs against
whole bacterial cell or
against specific proteins
Good negative test
Not all H. pylori-infected subjects develop
disease.
It depends on the strain heterogeneity
based on the expression of certain
virulence factors, Garza-Gonzalez et.al. World J Gastroenterol 2014; 20: 1438-49.
Non – Invasive Tests 3) Serology
Six highly immunogenic virulence factors,
CagA (Cytotoxin-associated-gene A),
VacA (Vacuolating Cytotoxin A), GroEL,
gGT, HcpC, and UreA, are currently being
detected.
Most of them are present in all strains but
expressed only in certain ones.
97.6% Sensitivity and 96.2% Specificity;
much higher than whole cell Abs
Garza-Gonzalez et.al. World J Gastroenterol 2014; 20: 1438-49.
Invasive Tests
Kanna et. al. Gastroenterology and Endoscopy news 2013 (e-published)
THANK YOU
