OBJECTIVEAccuracy of diagnostic methods for detecting Helicobacter pylori (H. pylori) infection among patients with bleeding peptic ulcers has not been thoroughly investigated. The aim of this study was to compare the diagnostic tests and their combined usage in detection of H. pylori infection in patients with bleeding gastric ulcers and without the use of nonsteroidal anti-inflammatory drugs.

METHODSA total of 57 patients who presented with bleeding gastric ulcers by endoscopy were enrolled. The status of H. pylori was identified by performing the rapid urease test (RUT), histology and (13)C-labeled urea breath test (UBT). The criteria for having H. pylori infection was a minimum of two positive tests.

RESULTSThe prevalence of H. pylori infection in our patient group was 80.7%. Among the three tests used: RUT, histology, and UBT, sensitivities were 56.5%, 97.8% and 100%, while specificities were 100%, 45.5% and 81.8%, respectively. The overall accuracies of the tests were 78.3%, 71.6% and 90.9%, respectively. Although UBT obtained significantly higher accuracy than histology (P = 0.02) as opposed to RUT (P = 0.11), UBT had significantly higher sensitivity than RUT (P < 0.001). In terms of combining any two of the three tests, more accuracy (98.9%) was achieved when both UBT and histology were used to confirm the diagnosis of the other. Conversely, failure to use combined tests generated the potential of missing a proper H. pylori diagnosis.

CONCLUSIONSUBT is superior to the other two tests in bleeding gastric ulcers. RUT lacks sensitivity for detection of H. pylori infection. However, the concomitant use of UBT and histology seems to be more accurate when gastric ulcers present with bleeding.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Breath Tests ; Female ; Helicobacter Infections ; diagnosis ; pathology ; Helicobacter pylori ; Humans ; Male ; Middle Aged ; Peptic Ulcer Hemorrhage ; complications ; Sensitivity and Specificity ; Stomach Ulcer ; complications ; Urea

Exotoxins produced by Actinobacillus (A.) pleuropneumoniae (Apx) play major roles in the pathogenesis of pleuropneumonia in swine. This study investigated the role of ApxI in hemolysis and cellular damage using a novel apxIA mutant, ApxIA336, which was developed from the parental strain A. pleuropneumoniae serotype 10 that produces only ApxI in vitro. The genotype of ApxIA336 was confirmed by PCR, Southern blotting, and gene sequencing. Exotoxin preparation derived from ApxIA336 was analyzed for its bioactivity towards porcine erythrocytes and alveolar macrophages. Analysis results indicated that ApxIA336 contained a kanamycin-resistant cassette inserted immediately after 1005 bp of the apxIA gene. Phenotype analysis of ApxIA336 revealed no difference in the growth rate as compared to the parental strain. Meanwhile, ApxI production was abolished in the bacterial culture supernatant, i.e. exotoxin preparation. The inability of ApxIA336 to produce ApxI corresponded to the loss of hemolytic and cytotoxic bioactivity in exotoxin preparation, as demonstrated by hemolysis, lactate dehydrogenase release, mitochondrial activity, and apoptosis assays. Additionally, the virulence of ApxIA336 appeared to be attenuated by 15-fold in BALB/c mice. Collectively, ApxI, but not other components in the exotoxin preparation of A. pleuropneumoniae serotype 10, was responsible for the hemolytic and cytotoxic effects on porcine erythrocytes and alveolar macrophages.
Actinobacillus pleuropneumoniae/genetics/*pathogenicity/*physiology ; Animals ; *Apoptosis ; Bacterial Proteins/genetics/metabolism ; Blotting, Southern ; Exotoxins/*genetics ; Hemolysin Proteins/genetics/metabolism ; *Hemolysis ; Macrophages, Alveolar/metabolism/*microbiology ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Swine ; Virulence