Helicobacter pylori overcomes natural immunity in repeated infections.

Repeated experimental reinfection of two subjects indicates that Helicobacter pylori infection does not promote an immune response protective against future reinfection. Our results highlight the importance of preventing reinfection after eradication, through public health initiatives, and possibly treatment of family members. They indicate difficulties for vaccine development, especially therapeutic vaccines.

Outcomes after 10 years of a community-based flexible sigmoidoscopy screening program for colorectal carcinoma.

OBJECTIVE: To evaluate the outcomes 10 years after a flexible sigmoidoscopy colorectal cancer (CRC) screening program in asymptomatic average-risk individuals. DESIGN, SETTING AND PATIENTS: In 1995, a program of flexible sigmoidoscopy-based screening of asymptomatic average-risk individuals aged 55-64 years was established at Fremantle Hospital, Western Australia. Insertion depths, pathological findings and subject-rated pain scores have been prospectively recorded. A follow-up flexible sigmoidoscopy examination was offered to attendees 5 years after the initial screening. Post-screening malignancies were determined by linkage with the Western Australian Cancer Registry in September 2006. MAIN OUTCOME MEASURES: Yield of neoplasia at initial and follow-up sigmoidoscopy, and the incidence of CRC detected after screening. RESULTS: Between 1995 and 2005, 3402 people underwent an initial flexible sigmoidoscopy screening examination (mean age, 60 years; women, 41%) and 1025 had a 5-year recall examination. Mean insertion depth was greater in men than women (60 cm v 52 cm, P<0.001). The insertion depth in women was more likely to be <40 cm (17% v 6%, P<0.001). Mean pain score was 2.9 for men and 4.0 for women (P<0.001). Fourteen per cent of initial screenings detected at least one adenoma. Over a mean follow-up time of 8 years, invasive CRC was detected by flexible sigmoidoscopy screening in 0.4% of participants; 0.7% of those with a normal result of screening later developed CRC, with 75% of these found proximal to the splenic flexure. CONCLUSIONS: Flexible sigmoidoscopy is a viable screening method, with well defined utility and limitations, for CRC screening of asymptomatic people with average risk.

Waiting times for colonoscopy and colorectal cancer diagnosis.

OBJECTIVE: To evaluate whether prolonged waiting times for colonoscopy in public hospitals could result in delayed diagnosis of colorectal carcinoma. DESIGN, SETTING AND PATIENTS: Analysis of all outpatient colonoscopies performed at a Western Australian tertiary teaching hospital, 1 November 2003 - 31 October 2005. Colonoscopy data, corresponding pathological findings, category of urgency at referral for colonoscopy, and waiting time for colonoscopy were obtained. Patients were coded as having cancer if it was diagnosed by colonoscopy or if colonoscopy identified a lesion subsequently diagnosed as cancer. MAIN OUTCOME MEASURES: Colorectal carcinoma detected by outpatient colonoscopy and length of waiting time to colonoscopy. RESULTS: 1632 outpatient colonoscopies were recorded. Category I patients received a colonoscopy within the recommended 30 days from referral. Median waiting times for Category II and Category III patients exceeded recommendations (observed, 113 days and 258 days; recommended, within 90 days and 180 days, respectively), although the number of cancers detected was low (2.4% and 0.6% of referrals, respectively in each category). Early- and late-stage cancers had similar median waiting times from referral to diagnosis. Age over 65 years and the blood-loss indications - a positive faecal occult blood test or iron deficiency/anaemia - were predictors of an increased risk of carcinoma at colonoscopy. CONCLUSIONS: Waiting time for colonoscopy was not associated with an increase in the proportion of late-stage cancers diagnosed. Age over 65 years and evidence of blood loss increased the likelihood of a cancer diagnosis.

Screening for hemochromatosis: patients with liver disease, families, and populations.

Hereditary hemochromatosis is a common autosomal- recessive disorder of iron overload usually occurring in individuals who are homozygous for a C282Y mutation in the hemochromatosis (HFE) gene. Current screening methods can detect affected individuals early in disease pathogenesis, enabling early institution of effective treatment that can restore normal life expectancy. Phenotypic screening of adults using transferrin saturation and serum ferritin levels identifies the majority of individuals who develop iron overload. HFE genotyping, when combined with serum biochemical measurements, has reduced reliance on liver biopsy as a diagnostic tool and is the preferred initial screening modality for families with an affected individual. Genetic testing has altered previously held views regarding the high level of penetrance of the disease. Although the majority of C282Y homozygotes develop increased body iron stores, end-organ damage occurs much less frequently than previously thought. Screening is recommended in high-risk groups and in those with a high index of clinical suspicion. Opportunistic screening during routine health assessments may also be recommended. However, large-scale screening of the average-risk population is not recommended on the basis of current evidence.

Nitazoxanide in treatment of Helicobacter pylori: a clinical and in vitro study.

Nitazoxanide (NTZ) is an antibiotic with microbiological characteristics similar to those of metronidazole but without an apparent problem of resistance. The aim of this study was the prospective evaluation of NTZ given as a single agent in the treatment of Helicobacter pylori infection. Twenty culture-positive patients with dyspepsia who had previously failed at least one course of H. pylori eradication therapy were enrolled. Subjects received 1 g of NTZ twice daily for 10 days. The safety and tolerability of the drug were assessed by physical examination, monitoring of adverse events, and clinical laboratory evaluation. Urea breath tests (UBTs) were performed 6 weeks posttreatment. H. pylori was isolated from UBT-positive patients by the string test or endoscopy with biopsy, and the MICs for these isolates were compared to those for isolates obtained pretherapy. The levels of tizoxanide, the active deacylated derivative of NTZ, were measured in blood, saliva, and tissue from two patients during treatment. The UBT results were positive for all 20 patients after completion of NTZ therapy. The MIC results demonstrated that the NTZ susceptibilities of none of the strains isolated from the patients posttherapy had changed significantly. No major adverse reactions were observed, but frequent minor side effects were observed. In conclusion, NTZ did not eradicate H. pylori when it was given as a single agent.

Evaluation of a new formulation CLOtest.

BACKGROUND AND AIMS: The CLOtest and other rapid urease detection kits are widely used in the endoscopic diagnosis of Helicobacter pylori. A new formulation CLOtest has been developed with the goal of obtaining a positive result more rapidly. The aims of this study were to validate the sensitivity and specificity of the new test and compare the time taken for a positive result to be visible in both the new and standard CLOtest. METHODS: Patients presenting for endoscopy at three Western Australian hospitals were prospectively enrolled. Gastric mucosal biopsies were obtained for the standard and new CLOtest and for histology. Grading of color change was conducted by staff blinded to the type of CLOtest used and conducted according to a standardized color chart. Helicobacter pylori status was defined by the combination of a positive standard CLOtest and histology, against which the new CLOtest was compared. Results were obtained at 1, 3 and 24 h, and at one center, at 10 min intervals for the first hour. RESULTS: Three hundred and thirty-five patients were enrolled. Eighty-eight Helicobacter pylori-positive individuals were identified. At 24 h, the new test correctly identified all 88, with one false-positive result (sensitivity 100%, specificity 99.6%). At 1 h, sensitivity was 93% with a number of early false-positive results reducing specificity to 96%. Compared to the current CLOtest, the new formulation became positive faster at 20 min (P = 0.001, n = 51), but was similar at 1 h (P = 0.06, n = 88) and equivalent at 3 h. CONCLUSIONS: The new formulation CLOtest is sensitive and specific, with a trend to give early positive results more quickly, although accuracy at 3 and 24 h is the same.