Incorporating sperm DNA fragmentation index with computer-assisted semen morphokinematic parameters as a better window to male fertility.

This study aimed to assess (1) the reproducibility of three sperm chromatin dispersion (SCD) assays for sperm DNA fragmentation, i.e., LensHooke R10® (R10), Halosperm G2® (G2), and BASO® (BA); (2) the correlation between computer-assisted semen analyzer (CASA) morphokinematic parameters and sperm DNA fragmentation index (DFI), and (3) the diagnostic value for male reproduction by combining semen morphokinematic parameters and DFI. Total 50 male participants were recruited, and all collected semen samples underwent semen analyses and SCD assays. Intra- and inter-observer variability of DFI data from different SCD measures was tested. In addition, the predictive ability of CASA parameters and DFI (with different cutoffs, i.e., 15% and 20%) for infertility was assessed using receiver operating characteristic curve analysis. We found that the G2 and R10 produced satisfactory variance coefficients (5.53%, 5.67%) compared to BA (14.8%). The DFI data from the R10 had lower intra-observer variability, in terms of higher intra-class coefficient (0.9615), than that of the G2 (0.8847) or BA (0.8824). Inter-observer variability of three SCD kits in scoring the DFI was comparable and satisfactory (concordance correlation coefficients ranging 0.9895-0.9630). The CASA parameters (i.e., total motility [r = -0.57], progression motility [r = -0.55], and rapidly progressive motility [r = -0.55]) were significantly correlated with DFI (P < 0.001). The predictive ability of the 15%-cutoff DFI data was better than that of the 20%-cutoff or continuous DFI data. The model comprising the CASA parameters, 15%-cutoff DFI, and 4%-cutoff normal morphology had the highest area under curve (0.8125) for infertility. For SCD assay, the R10 was the most reliable SCD assay to detect sperm DNA fragmentation. Combining the sperm DFI with CASA parameters might be a better diagnostic tool for male reproduction.

Overproduction of active efflux pump and variations of OprD dominate in imipenem-resistant Pseudomonas aeruginosa isolated from patients with bloodstream infections in Taiwan.

BACKGROUND: The emergence of imipenem-resistant Pseudomonas aeruginosa (IRPA) has become a great concern worldwide. The aim of this study was to investigate resistance mechanisms associated with bloodstream isolated IRPA strains in Taiwan. RESULTS: A total of 78 non-duplicated IRPA isolates were isolated from patients with bloodstream infection. The average prevalence of imipenem-resistance in those isolates was 5.9 % during a 10-year longitudinal surveillance in Taiwan. PFGE results showed high clonal diversity among the 78 isolates. VIM-2, VIM-3, OXA-10, and OXA-17 ß-lactamases were identified in 2 (2.6 %), 3 (3.8 %), 2 (2.6 %), and 1 (1.3 %) isolates, respectively. Active efflux pumps, AmpC ß-lactamase overproduction, and extended-spectrum AmpC cephalosporinases (ESACs) were found in 58 (74.4 %), 25 (32.1 %) and 15 (19.2 %) of IRPA isolates, respectively. oprD mutations with amino acid substitution, shortened putative loop L7, premature stop codon caused by point mutation, frameshift by nucleotide insertion or deletion, and interruption by insertion sequence were found in 19 (24.4 %), 18 (23.1 %), 15 (19.2 %), 14 (17.9 %), and 10 (12.8 %) of isolates, respectively. CONCLUSIONS: This study suggests that alterations in the OprD protein and having an active efflux pump are the main mechanisms associated with bloodstream isolated IRPA. Overproduction of AmpC, ESACs, and the presence of VIM- and OXA-type ß-lactamases play additional roles in reduced susceptibility to imipenem in P. aeruginosa isolates in Taiwan.

Characterization of the modified Hodge test-positive isolates of Enterobacteriaceae in Taiwan.

BACKGROUND/PURPOSE: The modified Hodge test is a phenotypic test to detect KPC-type carbapenemase producers among Enterobacteriaceae, as recommended by the Clinical Laboratory Standards Institute. However, false positive results were reported. In this study, we aimed to large-scale investigate the characterization of the modified Hodge test-positive isolates of Enterobacteriaceae collected between 2006 and 2010 in Taiwan. METHODS: Fifty-six isolates, including 24 Enterobacter cloacae, 17 Escherichia coli, 10 Klebsiella pneumoniae, and 5 Citrobacter freundii, tested positive with the modified Hodge test. The in vitro activities of 10 antimicrobial agents were determined by the agar dilution method. Boronic acid combined-disk test was used to further confirm the KPC producers. Phenotype of ESBL, AmpC, class B carbapenemases, and profile of outer membrane proteins were investigated by the confirmatory test, boronic acid disk method, 2-mercaptopropionic acid double-disk method, and urea/sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. ß-lactamase genes were examined by PCR and sequencing. RESULTS: These isolates were resistant to ceftazidime (100%), aztreonam (82.1%), ertapenem (64.3%), gentamicin (53.6%), ciprofloxacin (50%), levofloxacin (48.2%), cefepime (19.6%), imipenem (16.1%), meropenem (12.5%), and amikacin (8.9%). Phenotypic testing among isolates revealed the production of ESBLs, metallo-ß-lactamases (MBLs), and AmpC in 10 (17.9%), 16 (28.6%), and 12 (44.4%) isolates, respectively. Carbapenemase and non-carbapenemase ß-lactamase genes bla(TEM-1), bla(SHV), bla(CTX-M), bla(IMP-8), bla(CMY-2), and bla(DHA-1) were found in 32 (57.1%), 19 (33.9%), 4 (7.1%), 16 (28.6%), 14 (25%), and 5 (8.9%) of the strains, respectively. No class A and D carbapenemase genes were detected. Outer membrane protein profile showed obviously decreased expression in 49 (87.5%) isolates with positive result of modified Hodge test. CONCLUSIONS: Our data show that ESBLs, AmpC, and imipenemase-8 (IMP-8) carbapenemase coupled with decreased expression of outer membrane protein were prevalent in Enterobacteriaceae isolates testing positive for the modified Hodge test in Taiwan.

Impact of toxigenic Clostridium difficile colonization and infection among hospitalized adults at a district hospital in southern Taiwan.

BACKGROUND: The impact of toxigenic Clostridium difficile colonization (tCDC) in hospitalized patients is not clear. AIM: To study the significance of tCDC in hospitalized patients. METHODS: A prospective study in the medical wards of a regional hospital was performed from January to June 2011. Fecal samples collected from patients at the time of admission were tested for tcdB by real-time polymerase chain reaction (PCR) and cultured for C. difficile. The patients were followed up weekly or when they developed diarrhea during hospitalization. If C. difficile was isolated, tcdA and tcdB would be tested by multiplex PCR. The primary outcome was the development of C. difficile-associated diarrhea (CDAD). FINDINGS: Of 168 patients enrolled, females predominated (87, 51.8%), and the mean patient age was 75.4 years old. Approximately 70% of the patients were nursing home residents, and one third had a recent hospitalization within the prior three months. Twenty-eight (16.7%) patients had tCDC, including 16 (9.5%) patients with tCDC at the time of admission and 12 (7.2%) with tCDC during the follow-up period. With regard to the medications taken during hospitalization, the patients were more likely to have tCDC if they had received more than one class of antibiotics than if they had received monotherapy (odds ratio [OR] 6.67, 95% confidence interval [CI] 1.41-31.56, P = 0.01), particularly if they received a glycopeptide in combination with a cephalosporin or penicillin or a cephalosporin and a carbapenem. More patients with tCDC developed CDAD than those without tCDC (17.9%, 5/28 vs. 1.4%, 2/140, P = 0.002). Overall 7 (4.2%) of the 168 patients developed CDAD, and crude mortality rate of those with and without tCDC was similar (21.4%, 6/28 vs. 19.4%, 27/140, P = 0.79). CONCLUSION: Recent use of glycopeptides and ß-lactam antibiotics is associated with toxigenic C. difficile colonization, which is a risk factor for developing C. difficile-associated diarrhea.

Simultaneous laparoscopy for endometriotic women undergoing in vitro fertilization.

OBJECTIVE: The aim of this study was to investigate simultaneous laparoscopy in endometriotic women with infertility undergoing in vitro fertilization (IVF). MATERIALS AND METHODS: Forty-seven infertile patients with endometriosis were enrolled in this retrospective study and underwent IVF cycles in a university affiliated hospital. RESULTS: The chemical pregnancy, clinical pregnancy and live birth rates were statistically significantly different between patients with minimal or mild stage endometriosis and patients with moderate or severe stage endometriosis, who received simultaneous laparoscopy and modified IVF with a GnRH antagonist protocol. A higher live birth rate was achieved in IVF patients with minimal or mild stage endometriosis combined with laparoscopic treatment, than in patients who received traditional IVF with prior laparoscopic surgery for endometrioma. CONCLUSION: Simultaneous laparoscopy combined with a modified IVF (GnRH antagonist) protocol may benefit patients with minimal and mild endometriosis. Traditional GnRH agonist IVF cycles may improve the fecundity rates in women with moderate and severe endometriosis after laparoscopic treatment.

Characterization of ertapenem-resistant Enterobacter cloacae in a Taiwanese university hospital.

The emergence of carbapenem resistance in Enterobacteriaceae has become a great concern. The aim of this study was to characterize ertapenem-resistant Enterobacter cloacae isolates from a Taiwanese university hospital. A total of 355 nonduplicated E. cloacae isolates collected in 2007 were analyzed by antimicrobial susceptibility testing with and without an inhibitor of efflux pumps and AmpC ß-lactamase. The phenotype of extended-spectrum ß-lactamase (ESBL), profile of outer membrane proteins (OMPs), and clonal relatedness were investigated by the double-disk synergy test, urea/SDS-PAGE, and pulsed-field gel electrophoresis (PFGE), respectively. ß-Lactamase genes were examined by PCR and sequencing, and the expression of efflux pump gene acrB was evaluated by reverse transcription-PCR. The contribution of porin deficiency to resistance was investigated by restoring functional porin genes on plasmids. We demonstrated that ertapenem resistance was prevalent (53/355; 14.9%) in E. cloacae. Among the strains, IMP-8, SHV-12, and TEM-1 ß-lactamases were identified in 3 (5.7%), 40 (75.5%), and 46 (86.8%) isolates, respectively. PFGE showed clonal diversity among these isolates. Phenotypes of ESBL, AmpC ß-lactamase overproduction, an active efflux pump, and change in the expression of OMPs were found in 18 (34%), 11 (20.8%), 51 (96.2%), and 23 (43.4%) of ertapenem-resistant strains, respectively. Ertapenem MICs were restored in strains with OmpC and OmpF expression plasmids. This study suggests that ESBL, AmpC ß-lactamase overproduction, and decreased OMP expression combined with an active efflux pump contribute to the ertapenem resistance of E. cloacae. The presence of IMP-8 may also play a partial role in ertapenem resistance in Taiwan.

Heteroresistance to cephalosporins and penicillins in Acinetobacter baumannii.

Heteroresistance to antimicrobial agents may affect susceptibility test results and therapeutic success. In this study, we investigated heteroresistance to cephalosporins and penicillins in Acinetobacter baumannii, a major pathogen causing nosocomial infections. Two A. baumannii isolates exhibited heteroresistance to ampicillin-sulbactam, ticarcillin-clavulanic acid, cefepime, and cefpirome, showing a distinct colony morphology of circular rings within the inhibition halos. Pulsed-field gel electrophoresis (PFGE) and outer membrane protein (OMP) analysis demonstrated that subpopulations around the disks/Etest strips and the original strains all belonged to the same PFGE type and OMP profile. Population analysis profile (PAP) showed the presence of heteroresistant subpopulations with high cefepime resistance levels in two isolates (008 and 328). Interestingly, A. baumannii 008 contained two peaks: one was grown in the presence of up to 1 µg of cefepime/ml, the other apparently occurred when the concentration of cefepime was raised to 256 µg/ml. After serial passages without exposure to cefepime, the PAP curve maintained the same trend observed for the original strain of A. baumannii 008. However, the PAP curve showed a shift to relatively lower cefepime resistance (from 256 to 64 µg/ml) in A. baumannii 328 after 10 passages in antibiotic-free Mueller-Hinton agar plates. Convergence to a monotypic resistance phenotype did not occur. Growth rate analysis revealed that slower growth in resistant subpopulations may provide a strategy against antibiotic challenge. To our knowledge, this is the first report of heteroresistance to cephalosporins and penicillins in A. baumannii.

Use of an oxytocin antagonist in in vitro fertilization-embryo transfer for women with repeated implantation failure: a retrospective study.

OBJECTIVE: This retrospective study aimed to investigate the use of an oxytocin antagonist in improving the pregnancy outcome of in vitro fertilization-embryo transfer (IVF-ET) in patients with repeated implantation failure (RIF). MATERIALS AND METHODS: A total of 150 infertile couples with RIF undergoing IVF-ET were divided into three groups. Patients who did not receive atosiban were used as controls (Group 1; n=80). Forty patients received a single bolus dose (6.75mg, 0.9mL/vial) of atosiban before ET (Group 2), and 30 patients received a bolus dose of 6.75mg atosiban followed by infusion at 18mg/hr for 3 hours immediately after ET (Group 3). RESULTS: A significantly higher implantation rate (30.21%) was noted in Group 2 compared with Groups 1 and 3 (11.8% and 15.9%, respectively; p=0.0006). The clinical pregnancy rate of Group 2 (37.5%) was significantly higher than that of Groups 1 (12.5%) and 3 (20%) (p=0.0057). The live birth rate was significantly higher in Group 2 (35%) than in Groups 1 and 3 (10% and 16.67%, respectively; p=0.0031). CONCLUSION: These results suggest that IVF-ET using lower dosage of atosiban may improve pregnancy outcomes of patients with RIF.

Clinical and microbiological characteristics of community-acquired Staphylococcus lugdunensis infections in Southern Taiwan.

Most Staphylococcus lugdunensis strains (49/59, 83%) were related to clinical infections, were susceptible to most antimicrobial agents with an overall oxacillin-resistant rate of 5% (3/58), and carried relatively great genetic diversity. Community-acquired infections (41/49, 84%) were dominant, often developed in patients with comorbidity, and had rather benign clinical courses without mortality.

Helicobacter pylori with stronger intensity of CagA phosphorylation lead to an increased risk of gastric intestinal metaplasia and cancer.

BACKGROUND: Nearly all Taiwanese H. pylori stains are cagA-genopositive and encode CagA protein. In this study, we evaluated whether different intensity of tyrosine phosphorylated-CagA (p-CagA) had an impact on the clinical diseases and histological outcomes in this area. RESULTS: We enrolled 469 dyspeptic patients and prospectively obtained the gastric biopsy specimens and the H. pylori isolates. These patients were categorized according to the clinical diseases, such as duodenal ulcer, gastric ulcer, gastric cancer, and gastritis with or without intestinal metaplasia. Their gastric specimens were reviewed by the updated Sydney's system. Furthermore, a total of 146 patients were randomly selected from each clinical category for evaluation of their isolates' p-CagA intensity by in vitro AGS cells co-culture. The p-CagA was sparse in 30 (20.5%), weak in 59 (40.5%), and strong in 57 (39%) isolates. The isolates from the patients of gastric cancer or gastritis with intestinal metaplasia had stronger p-CagA intensity than those of gastritis without intestinal metaplasia (p ≤ 0.002). Moreover, the patients infected with isolates with strong or weak p-CagA intensity had a higher risk of gastric intestinal metaplasia (p < 0.05, odds ratio 3.09~15.26) than those infected with sparse p-CagA isolates. CONCLUSIONS: Infection with H. pylori stains with stronger p-CagA intensity may lead to an increased risk of gastric intestinal metaplasia and cancer.

Airway infection predisposes to peristomal infection after percutaneous endoscopic gastrostomy with high concordance between sputum and wound isolates.

BACKGROUND: Peristomal infection is common after percutaneous endoscopic gastrostomy. This study aims to evaluate the correlation between airway and peristomal infected pathogens. METHODS: Before the procedure, sputum cultures were prospectively performed for the patients with airway symptoms. All the patients received prophylactic antibiotics. Once peristomal infection occurred, the wound cultures were obtained to analyze the antibiotic susceptibilities of the pathogens. The paired isolates, with concordance between sputum and wound cultures, were validated for their clone identity using pulsed-field gel electrophoresis. RESULTS: One hundred twelve patients were enrolled, and 30 patients had peristomal infection. The 31 patients with airway pathogens had a 10-fold higher risk of peristomal infection than the other 81 without airway pathogens (95% CI, 3.85-26.4, p < 0.001). Among patients collected with paired isolates from wound and sputum, 85% had concordant microorganism species. In the paired concordant isolates, 94% had indistinguishable antibiogram, and nearly 90% were clonally identical in pulsed-field gel electrophoresis. CONCLUSIONS: Patients with airway infection have an increased risk of peristomal infection after percutaneous endoscopic gastrostomy. Concerning the high concordance between infected wound and sputum isolates of such patients, the selection of appropriate prophylactic antibiotics could be individual to cover the microorganisms isolated from sputum.

Short-term celecoxib to regress long-term persistent gastric intestinal metaplasia after Helicobacter pylori eradication.

BACKGROUND AND AIM: The intestinal metaplasia (IM) has overexpressions of cyclooxygenase-2 (COX-2) and beta-catenin. This pilot study assessed whether celecoxib, a selective COX-2 inhibitor, could regress IM that persisted long term after Helicobacter pylori eradication. METHODS: Thirty-three patients with H. pylori eradication were enrolled in the present study due to the persistence of IM after a 3-year follow up. These patients received celecoxib 200 mg/day for 8 weeks, and were serially checked for levels of blood urea nitrogen and creatinine once per 2 weeks. After 8-week celecoxib treatment, IM regression was assessed by panendoscopy. The gastric specimens, taken before and after celecoxib, were immunochemically stained for COX-2 and beta-catenin. RESULTS: The intention-to-treat and per-protocol analyses to the rates of IM regression by 8-week celecoxib treatment were 24.2% (8/33) and 28.6% (8/28), respectively. All enrolled patients had no renal impairment. Even in the patients without total IM regression, mean IM scores in the antrum decreased after 8-week celecoxib treatment (P = 0.007). The patients with complete regression of IM after 8-week celecoxib treatment had a significantly lower COX-2 expression, but not beta-catenin expression, at enrollment than those patients without IM regression (P = 0.031). CONCLUSION: Short-term celecoxib treatment can be safe and promising to regress long-term persistent IM after H. pylori eradication.

Host single nucleotide polymorphisms of MMP-9 -1562/TIMP-1 372 have gender differences in the risk of gastric intestinal metaplasia after Helicobacter pylori infection.

BACKGROUND: Helicobacter pylori infection causes chronic gastric inflammation and intestinal metaplasia (IM), related with deregulation of Wnt pathway and over-expressions of COX-2, matrix metalloproteinase (MMP), and tissue inhibitors of matrix metalloproteinase (TIMP). We thus test the host genomic predispositions related to the risk of IM after H. pylori infection. METHODS: We enrolled 296 H. pylori-infected patients to provide gastric biopsies for histology and genomic DNA for genotypes of single nucleotide polymorphisms (SNPs), including APC, COX-2, IL-1B, IL-1RN, IL-10, MMP-2, MMP-9, TIMP-1, and TIMP-2 determined by sequence specific oligonucleotide probe, sequence specific primers, restriction fragment length polymorphism, or real-time polymerase chain reaction. RESULTS: There was no association between the presence of IM and SNPs in APC, COX-2, IL-1B, IL-1RN, IL-10, MMP-2, and TIMP-2. The risk of IM was increased up to 2.29-folds in males with TIMP-1 372 C, and 3.03-fold in females with T carrier (p < .05). The combination genotype of MMP-9 -1562/TIMP-1 372 as CC/C and CT/T in males had a 4.5-fold increased risk of IM, as compared to CC/T (p < .05). Females with such combination genotype as CC/T-carrier had a 3-fold risk of IM than males with CC/T (p < .05). In contrast, males' combination genotype as CC/C had a 3-fold risk of IM than females with CC/CC (p = .05). CONCLUSIONS: The host MMP-9 -1562/TIMP-1 372 SNPs had gender differences in the risk of IM after H. pylori infection, and could possibly serve as a host factor to identify the risk group harboring gastric precancerous changes after H. pylori infection.

Host Wnt/beta-catenin pathway triggered by Helicobacter pylori correlates with regression of gastric intestinal metaplasia after H. pylori eradication.

Helicobacter pylori eradication can reverse gastric intestinal metaplasia (IM) in some but not all patients. H. pylori induces high levels of nuclear beta-catenin staining in IM tissues, as well as overexpression of cyclooxygenase-2 (COX-2). This study investigated whether the Wnt/beta-catenin pathway plays a role in IM regression following H. pylori eradication. Sixty-five H. pylori-infected patients with IM who had achieved successful H. pylori eradication provided paired gastric samples before and after eradication to analyse the persistence of IM, and to assess COX-2 and nuclear beta-catenin expression. The host genotypes of single nucleotide polymorphisms (SNPs) of the COX-2, beta-catenin (CTNNB1) and adenomatous polyposis coli (APC) genes were analysed. In addition, expression of beta-catenin, E-cadherin and phosphorylated and unphosphorylated glycogen synthase kinase 3beta (GSK-3beta) in cell lines challenged with H. pylori isolates from patients with and without IM persistence was compared by immunoanalysis. After a mean 33.9-month follow-up after H. pylori eradication, 44 patients (67.7%) with IM persistence had a higher rate of high-level nuclear beta-catenin expression in IM tissue than those without IM persistence (P=0.008). The patients with IM persistence had a higher rate of AA, GG and AA APC SNP genotypes at positions 4479, 5268 and 5465, respectively, than the patients without IM persistence (P=0.022). The H. pylori isolates from the patients with IM regression after H. pylori eradication induced more phospho-GSK-3beta in AGS cells than isolates from patients with IM persistence (P=0.011). It is likely that interactions with H. pylori and the patient's Wnt/beta-catenin genetic predisposition determine the outcome of IM persistence following H. pylori eradication.

Prevalence of primary fluoroquinolone resistance among clinical isolates of Helicobacter pylori at a University Hospital in Southern Taiwan.

BACKGROUND: Fluoroquinolone-containing therapy is effective in eradicating Helicobacter pylori. However, the resistance rate of H. pylori to fluoroquinolones in Taiwan has not yet been reported. In this study, we aimed to investigate the susceptibility to antibiotics commonly used in eradication schedules and fluoroquinolones in H. pylori. METHODS: A total of 210 clinical isolates of H. pylori were collected from April 1998 to September 2007 from patients in southern Taiwan. The in vitro activities of six antimicrobial agents were determined by the agar dilution method and Etest. The mutations in quinolone resistance-determining regions of gyrA and gyrB were investigated by direct sequencing. RESULTS: Overall, 5.7% of the isolates were resistant to ciprofloxacin and levofloxacin. The resistance rate to amoxicillin, clarithromycin, metronidazole, and tetracycline was 1.0% (two of 210), 9.5% (20 of 210), 27.6% (58 of 210), and 0.5% (one of 210), respectively. The resistance rate to either ciprofloxacin or to levofloxacin increased from 2.8% (1998-2003) to 11.8% (2004-2007). The mutations in gyrA at N87 or D91 had an impact on primary fluoroquinolone resistance in H. pylori. Garenoxacin, but not moxifloxacin, had a good in vitro inhibitory effect against ciprofloxacin/levofloxacin-resistant strains compared with objective minimal inhibitory concentration values. CONCLUSIONS: Drug resistance to ciprofloxacin and levofloxacin in H. pylori collected from 2004 to 2007 increased significantly compared with resistance level observed during 1998-2003. The continuous surveillance of quinolone resistance among H. pylori is important in this area.

Association of nonsynonymous substitutions in the intermediate region of the vacA gene of Helicobacter pylori with gastric diseases in Taiwan.

The amino acid sequences corresponding to the vacA intermediate region from 39 isolates of Helicobacter pylori were investigated. The substitution of a G for the third S in the i1-type cluster B sequence (QASEGITSSK) conferred a greater risk of gastric diseases (P < 0.03; Fisher's exact test). The conserved substitutions of an F for the Y in the cluster A sequence and of an M for the second N in the i1-type cluster C sequence could be a marker of VacA in the Taiwanese strains.

Emergence of fluoroquinolone resistance in group B streptococcal isolates in Taiwan.

Of 1,994 group B streptococcal isolates collected, 26 (1.3%) of the isolates were resistant to levofloxacin, and cross-resistance to other fluoroquinolones was observed. The emergence and prevalence of high-level fluoroquinolone resistance in genetically unrelated isolates were linked to the presence of gyrA, parC, and parE triple mutations in each isolate.

Interaction between host gastric Sialyl-Lewis X and H. pylori SabA enhances H. pylori density in patients lacking gastric Lewis B antigen.

OBJECTIVES: We tested whether the interaction between host gastric Le(x) antigen and the SabA protein of H. pylori determined gastric colonization density. METHODS: A total of 145 H. pylori-infected patients were assessed for their bacterial density and gastric Le(b) and sialyl-Le(x) expression. Their corresponding H. pylori isolates were tested for babA2 and sabA genotype by PCR. The sabA-genopositive PCR products were sequenced to check for mutations affecting SabA expression. The BabA and SabA expressions of each isolate were confirmed by Western blotting. RESULTS: All 145 H. pylori isolates were babA2-genopositive and expressed BabA. There were 116 (80%) sabA-genopositive isolates, but only 45 (31%) of the isolates expressed SabA. Sequence of sabA-genopositive PCR products was achieved in 92 isolates, of which 60% had regular CT repeat-pairs and the other 40% had a unique deletion of the CT repeats. Neither the deletion nor the different CT repeat-pairs in the sabA region were totally correlated with SabA expression, defined by Western blotting. H. pylori density was higher in those expressing gastric sialyl-Le(x) antigen (which interacts with SabA) (p < 0.001) only in those patients expressing weak or no gastric Le(b) antigen (which would interact with BabA), not in those with evident expression of gastric Le(b) antigen. CONCLUSIONS: In Taiwan, H. pylori isolates are 100% BabA-positive, but only 31% of them express SabA. The interaction between gastric sialyl-Le(x) and SabA of H. pylori determines the colonization density of patients expressing gastric Le(b) weakly or not at all.