Study on total residual oxidant decay in long-distance seawater intake pipeline of cooling system.

Electrochlorination is often used for biofouling control along the water intake pipeline of seawater cooling system, but with the increasing of pipeline length, this process needs to be further improved. In this study, the dynamic circulation and field pilot test were used to simulate the long-distance seawater intake pipeline, investigating total residual oxidant (TRO) decay and its influencing factors by comparing the bench test. The results showed that intermediate dosing could increase terminal TRO, but also reduce the CT value, resulting in decline of local inactivation effect. The initial concentration of dynamic cycle test was higher than that of bench test under the same terminal TRO, and the difference value between the two was affected by holding time. When the initial concentration was greater than 8.5 mg L-1, TRO decay rate was proportional to the seawater flow rate and inversely proportional to the initial concentration. The initial concentration of 8.5-10 mg L-1 could meet TRO decay requirement under 3 h holding time, and the dosing concentration could be reduced to 6 mg L-1 when the temperature was low. The results provided important guidance for the actual operation of biofouling control in long-distance water intake pipelines of cooling system.

Application of gene chip technology in the diagnostic and drug resistance detection of Helicobacter pylori in children.

BACKGROUND AND AIMS: Helicobacter pylori (HP) culture for diagnosing HP infection is time-consuming and technologically complex. This study evaluated the clinical significance of gastric mucosal gene chip technology in the rapid diagnosis of HP infection and detection of drug resistance in children. METHODS: Patients (between the age of 2.5 and 16.0 years old) manifesting gastrointestinal symptoms were enrolled in this study. HP culture of gastric mucosa and drug sensitivity test were performed. A gene chip of gastric mucosa was used to detect the presence of HP infection, some single nucleotide polymorphisms in HP drug resistance genes, or associated gene mutation. DNA sequencing was investigated and compared with the gene chip test results. RESULTS: Out of 267 cases, HP culture was positive in 169 cases and negative in 98 cases. HP detection by the gene chip method was positive in 208 cases and negative in 59 cases. The sensitivity, specificity, and accuracy of the gene chip technology for diagnosing HP infection were 96.1, 85.0, and 93.6%, respectively. HP resistance gene locus using the gene chip showed the main mutation locus of clarithromycin to be 2143A/G, levofloxacin at locus GyrA 91 and GyrA 87, and amoxicillin at PBP1 556ser. Concordance rates between gene chip and DNA sequencing for VacA-S/M, 16S rRNA, 23S rRNA, and GyrA were greater than 95%, and that of PBP1 was greater than 82%. CONCLUSION: Gastric mucosal gene chip technology can be used for rapid diagnosis and drug resistance detection of HP infection in children.

Antibiotics resistance of Helicobacter pylori in children with upper gastrointestinal symptoms in Hangzhou, China.

BACKGROUND: The decreasing eradication rate of Helicobacter pylori is mainly because of the progressive increase in its resistance to antibiotics. Studies on antimicrobial susceptibility of H. pylori in children are limited. This study aimed to investigate the resistance rates and patterns of H. pylori strains isolated from children. MATERIALS AND METHODS: Gastric mucosa biopsy samples obtained from children who had undergone upper gastrointestinal endoscopy were cultured for H. pylori, and susceptibility to six antibiotics (clarithromycin, amoxicillin, gentamicin, furazolidone, metronidazole, and levofloxacin) was tested from 2012-2014. RESULTS: A total of 545 H. pylori strains were isolated from 1390 children recruited. The total resistance rates of H. pylori to clarithromycin, metronidazole, and levofloxacin were 20.6%, 68.8%, and 9.0%, respectively. No resistance to amoxicillin, gentamicin, and furazolidone was detected. 56.1% strains were single resistance, 19.6% were resistant to more than one antibiotic, 16.7% for double resistance, and 2.9% for triple resistance in 413 strains against any antibiotic. And the H. pylori resistance rate increased significantly from 2012-2014. There was no significant difference in the resistance rates to clarithromycin, metronidazole, and levofloxacin between different gender, age groups, and patients with peptic ulcer diseases or nonulcer diseases. CONCLUSIONS: Antibiotic resistance was indicated in H. pylori strains isolated from children in Hangzhou, and it increased significantly during the 3 years. Our data strongly support current guidelines, which recommend antibiotic susceptibility tests prior to eradication therapy.

Investigation of Helicobacter pylori infection among symptomatic children in Hangzhou from 2007 to 2014: a retrospective study with 12,796 cases.

BACKGROUND AND AIM: The infection of Helicobacter pylori (H. pylori) is acquired in childhood and the prevalence vary greatly in different countries and regions. The study aimed to investigate the characteristics of H. pylori infection among children with gastrointestinal symptoms in Hangzhou, a representative city of eastern China. METHODS: A systematic surveillance of H. pylori infection according to the 13C-urea breath test was conducted from January 2007 to December 2014 in the Children's hospital, Zhejiang University School of Medicine. The demographic information and main symptoms of every subject were recorded. RESULTS: A total of 12,796 subjects were recruited and 18.6% children evaluated as H. pylori positive. The annual positive rates decreased from 2007 to 2014 (χ2 = 20.461, p < 0.01). The positive rates were 14.8%, 20.2% and 25.8% in 3-6, 7-11 and 12-17 years age group respectively, which increased with age (χ2 = 116.002, p < 0.01). And it was significantly higher in boys than girls (χ2 = 15.090, p < 0.01). Multivariate logistic regression identified possible risk factors for H. pylori infection. Age, gender, gastrointestinal symptoms and history of H. pylori infected family member were all significantly associated with H. pylori infection (all p < 0.05). CONCLUSIONS: H. pylori infection rates in children with gastrointestinal symptoms were lower than most of those reported in mainland China. Further studies are required to determine the prevalence in the general population. Comprehensively understanding of the characteristics and the possible risk factors of H. pylori infection will be helpful to its management strategies in children in China.