[Clinical analysis of endoscopic esophageal dilation for the treatment of corrosive esophageal strictures in children]. / å† é•œä¸‹é£Ÿç®¡æ‰©å¼ æ²»ç–—å„¿ç«¥è èš€æ€§é£Ÿç®¡ç‹­çª„çš„ä¸´åºŠåˆ†æž.

OBJECTIVES: To investigate the clinical application of endoscopic esophageal dilation in the treatment of corrosive esophageal strictures in children. METHODS: A retrospective analysis was performed on the clinical data of 15 children with corrosive esophageal strictures who underwent endoscopic esophageal dilation in Children's Hospital, Zhejiang University School of Medicine. The clinical features, treatment modality of endoscopic esophageal dilation, number of dilations, complications, and prognosis were reviewed. RESULTS: A total of 96 esophageal dilations were performed in the 15 children with corrosive esophageal strictures, with a median of 6 dilations per child. Among them, 9 children (60%) underwent 6 or more dilations. The children with a stricture length of >3 cm had a significantly higher number of dilations than those with a stricture length of ≤3 cm (P<0.05). The children with strictures in a single segment had a significantly better treatment outcome than those with strictures in multiple segments (P=0.005). No complication was observed during all sessions of dilation. The overall effective rate (including significant improvement and improvement) of endoscopic esophageal dilation treatment was 87%, with 2 cases of failure. CONCLUSIONS: Endoscopic esophageal dilation is an effective and relatively safe treatment method for corrosive esophageal strictures in children, and children with strictures in a single segment tend to have a better treatment outcome than those with strictures in multiple segments.

Diagnosis, treatment, and prevention of severe acute hepatitis of unknown etiology in children.

BACKGROUND: Severe acute hepatitis of unknown etiology in children has recently exhibited a global trend of concentrated occurrence. This review aimed to summarize the current available information regarding the outbreak of severe acute hepatitis and introduce our hospital's previous experiences with the diagnosis and treatment of severe acute hepatitis for reference. DATA SOURCES: Websites including the UK Health Security Agency, European Centre for Disease Prevention and Control, CDC, WHO, and databases including PubMed/Medline, Cochrane Library, Embase and Web of Science were searched for articles on severe acute hepatitis in children. RESULTS: As of May 26, 2022, a total of 650 cases have been reported in 33 countries; at least 38 (6%) children required liver transplantation, and nine (1%) died. Cases are predominantly aged between 3 and 5 years old, and there are no epidemiological links among them. The common manifestations are jaundice, vomiting and pale stools. Adenovirus tested positive in most cases, and SARS-CoV-2 and other viruses were detected in a few cases, but virus particles were not found in liver tissue. Adenovirus immunohistochemistry showed immunoreactivity in the intrasinusoidal lumen from some liver samples. The hierarchical treatment includes symptomatic and supportive therapy, management of coagulation disorders and hepatic encephalopathy, artificial liver support, and liver transplantation (approximately 6%-10% of cases require liver transplant). CONCLUSIONS: The etiology of this severe acute hepatitis in children is not clear. The clinical features are severe acute hepatitis with significantly elevated liver enzymes. Clinicians need to be alert to children with hepatitis.

[Effectiveness of induction therapy with exclusive enteral nutrition in pediatric Crohn's disease]. / å ¨è‚ å† è¥å »å¯¹å„¿ç«¥å ‹ç½—æ©ç— è¯±å¯¼ç¼“è§£ç–—æ•ˆç ”ç©¶.

OBJECTIVES: To evaluate the effectiveness of induction therapy with exclusive enteral nutrition (EEN) in pediatric Crohn's disease (CD). METHODS: A retrospective analysis was performed on the medical data of 62 children with CD who received EEN in Children's Hospital, Zhejiang University School of Medicine, from March 2013 to August 2021. The medical data included general information and height, weight, Pediatric Crohn's Disease Activity Index (PCDAI), Crohn's Disease Endoscopic Index of Severity, C-reactive protein, erythrocyte sedimentation rate, and serum albumin level before treatment and after 8 weeks of treatment. The changes in the above indicators were compared before and after treatment. RESULTS: Among the 62 children with CD, there were 39 boys (63%) and 23 girls (37%), with a mean age of (11.9±3.0) years at diagnosis. Among the 55 children who completed EEN treatment for at least 8 weeks, 48 (87%) achieved clinical remission at week 8. PCDAI at week 8 was significantly lower than that before treatment (P<0.001). Except for 17 children with involvement of the small intestine alone and 3 children with involvement of the colon who did not receive colonoscopy reexamination, the remaining 35 children with involvement of the colon received colonoscopy reexamination after the 8-week EEN treatment. Of the 35 children, 29 (83%) achieved mucosal healing. As for the 48 children who achieved clinical remission at week 8, there were significant improvements in height-for-age Z-score and body mass index-for-age Z-score at week 8 (P<0.01). As for the 7 children who did not achieve clinical remission at week 8, there were no significant changes in height-for-age Z-score and body mass index-for-age Z-score at week 8 (P>0.05). CONCLUSIONS: The 8-week EEN treatment has a good effect on clinical remission and mucosal healing in children with CD. For the children with CD achieving clinical remission, EEN can improve their height and body mass index.

Nasogastric or nasojejunal feeding in pediatric acute pancreatitis: a randomized controlled trial.

BACKGROUND: The aim of this study was to compare nasogastric (NG) feeding with nasojejunal (NJ) feeding when treating pediatric patients with acute pancreatitis (AP). METHODS: We performed a single-center, prospective, randomized, active-controlled trial involving 77 pediatric patients with AP from April 2014 to December 2017. The patients were randomized into two groups: the NG tube feeding group (34 patients) and the NJ tube feeding group (33 patients). The primary outcome measures included the enteral nutrition intolerance, the length of tube feeding time, the recurrent pain of pancreatitis and complications. RESULTS: A total of 62 patients with AP (31 patients for each group) came into the final analysis. No differences were found in baseline characteristics, pediatric AP score and computed tomography severity score between the two groups. Three (9.7%) patients in the NG group and one (3.2%) patient in the NJ group developed intolerance (relative risk = 3.00, 95% confidence interval 0.33-27.29, P = 0.612). The tube feeding time and length of hospital stay of the NG group were significantly shorter than those of the NJ group (P = 0.016 and 0.027, respectively). No patient died in the trial. No significant differences were found in recurrent pain, complications, nutrition delivery efficacy, and side effects between the two groups. CONCLUSIONS: NG tube feeding appears to be effective and safe for acute pediatric pancreatitis compared with NJ tube feeding. In addition, high qualified, large sample sized, randomized controlled trials in pediatric population are needed.

[Inflammatory bowel disease with growth hormone deficiency in adolescents: an analysis of 4 cases and literature review].

Inflammatory bowel disease (IBD) is a chronic recurrent non-specific inflammatory disease in the intestinal tract. About 10%-56% of children with Crohn's disease and about 10% of children with ulcerative colitis have growth retardation. This study reports four adolescents with IBD and growth hormone deficiency who were diagnosed with Crohn's disease. There were three boys and one girl, with an age of 11.0-13.9 years and a disease duration of 11-85 months at diagnosis. The four patients had the involvement of the small intestine only, the colon only, both the small intestine and the upper gastrointestinal tract, and both the small intestine and the colon respectively. The pediatric Crohn's disease activity index ranged from 27.5 to 45 points. All four patients had a height-for-age Z-score (HAZ) of <-2, and the growth hormone provocative test suggested growth hormone deficiency. Of all four patients, two received recombinant human growth hormone combined with infliximab, one received infliximab only, and one received recombinant human growth hormone combined with mercaptopurine. All four patients had an improvement in HAZ after treatment.

[Clinical features and prognosis of gastrointestinal injury due to foreign bodies in the upper gastrointestinal tract in children: a retrospective analysis of 217 cases].

OBJECTIVE: To study the clinical features and prognosis of gastrointestinal injury caused by foreign bodies in the upper gastrointestinal tract in children. METHODS: A retrospective analysis was performed for the clinical data of 217 children who were diagnosed with foreign bodies in the upper gastrointestinal tract complicated by gastrointestinal injury by gastroscopy from January 2011 to December 2016, including clinical features, gastroscopic findings, complications, and prognosis. RESULTS: Among the 217 children, 114 (52.5%) were aged 1-3 years. The most common foreign body was coin (99/217, 45.6%), followed by hard/sharp-edged food (45/217, 20.7%) and metal (35/217, 16.1%). The most common gastrointestinal mucosal injury was ulceration (43.8%), followed by erosion (33.2%). Compared with other foreign bodies, button cells were significantly more likely to cause esophageal perforation (P<0.01). The esophagus was the most commonly injured organ (207/217, 95.4%). Of all the 217 children, 24 (11.1%) experienced infection. The children with perforation caused by foreign bodies had a significantly higher incidence rate of infection than those with ulceration caused by foreign bodies (P=0.003). Of all the 217 children, 204 (94.0%) underwent successful endoscopic removal of foreign bodies. Among these children, 98 were hospitalized due to severe mucosal injury and were given anti-infective therapy, antacids, and supportive care including enteral nutrition through a nasogastric tube and/or parenteral nutrition. Of all the children, 10 left the hospital and were lost to follow-up, and all the other children were improved and discharged. CONCLUSIONS: Most cases of foreign bodies in the upper gastrointestinal tract occur at 1-3 years of age. Coin, hard/sharp-edged food, and metal are the most common foreign bodies. Button cells are more likely to cause esophageal perforation. The incidence rate of secondary infection increases with the increasing severity of gastrointestinal mucosal injury. Children undergoing endoscopic removal of foreign bodies and enteral nutrition through a nasogastric tube tend to have a good prognosis.

Phenotypic and genotypic characterization of inflammatory bowel disease in children under six years of age in China.

AIM: To analyze clinical differences between monogenic and nonmonogenic very-early-onset inflammatory bowel disease (VEO-IBD) and to characterize monogenic IBD phenotypically and genotypically via genetic testing. METHODS: A retrospective analysis of children aged 0 to 6 years diagnosed with VEO-IBD in a tertiary hospital in southern China from 2005 to 2017 was performed. Clinical data for VEO-IBD patients were collected, and genetic characteristics were analyzed using whole exome sequencing or target gene panel sequencing. RESULTS: A total of 54 VEO-IBD patients were included in this study. A diagnosis of Crohn's disease (CD) or CD-like intestinal manifestations accounted for 72.2% of the VEO-IBD cases. Nine patients (16.7%) were identified by genetic testing as having monogenic IBD. The median age of diagnosis in the monogenic group was younger than that of the nonmonogenic IBD group, at 18 mo (interquartile range (IQR): 4 to 78) and 43.5 mo (IQR: 3 to 173), respectively; the P-value was 0.021. The incidence of perianal disease in the monogenic group was higher than that in the nonmonogenic group (P = 0.001). However, there were no significant differences between weight-for-age and height-for-age Z-scores between the two groups, and similar laboratory results were obtained for the two groups. Five patients were found to have IL10 receptor mutation, two patients had chronic granulomatous disease, one patient had common variable immunodeficiency disease, and one patient had X-linked inhibitor of apoptosis protein deficiency. CONCLUSION: A high proportion of monogenic IBD was observed in the VEO-IBD group, especially with disease onset before the age of 6 mo. Monogenic IBD and nonmonogenic IBD exhibited similar clinical features. Furthermore, next-generation sequencing played an important role in the diagnosis of monogenic IBD, and IL10 receptor mutation was predominant in this cohort.

[Association between vitamin D receptor gene polymorphisms and pediatric Crohn's disease in China: a study based on gene sequencing].

OBJECTIVE: To investigate the association between TaqI, BsmI, and ApaI polymorphisms of vitamin D receptor (VDR) gene and pediatric Crohn's disease (CD) in China. METHODS: Nineteen children with CD were selected as a case group, and 122 healthy children who underwent physical examination were selected as a control group. Serum 25-hydroxyvitamin D3 [25(OH)D3] levels were measured using ELISA. The TaqI, BsmI, and ApaI polymorphisms of VDR gene were determined by gene sequencing, and the two groups were compared in terms of genotype and allele frequencies. RESULTS: The case group had significantly lower serum 25(OH)D3 levels than the control group (17.3±2.4 ng/mL vs 26.9±2.1 ng/mL; P<0.05). There were no significant differences in the frequencies of genotypes and alleles of TaqI, BsmI, and ApaI polymorphisms between the case and control groups (P>0.05). CONCLUSIONS: Children with CD have low serum 25(OH)D3 levels. TaqI, BsmI, and ApaI polymorphisms of VDR gene may not be associated with susceptibility to CD among the Chinese population.

A Chinese girl molecularly diagnosed with Alagille syndrome.

BACKGROUND: Alagille syndrome (AGS) is a rare or fatal disease affecting multiple systems including the liver, heart, eyes, skeleton and face. It has been considered a genetically heterogeneous disorder of the Notch signaling pathway. METHODS: A 28-month-old Chinese girl with congenital heart disease and jaundice was diagnosed with Alagille syndrome by liver biopsy showing a paucity of the intrahepatic bile ducts. Variants of the JAG1 gene were detected by DNA sequencing in the patient and her unaffected father. RESULTS: A heterozygous missense mutation was identified in exon 2 of the JAG1 gene in the proband but not in exon 2, 4, 6, 9, 17, 23, 24 by DNA sequencing in her father. The mutation G-->T change was seen at position 133 in the cDNA sequence (c.133 G-->T), causing a substitution of a leucine for a valine (V45L) residue in the N terminus between signal peptide and DSL domain of the Notch ligand. This mutation, however, was absent in her father. CONCLUSION: Genes in the Notch signaling pathway should be further studied in AGS, and used to confirm clinical or prenatal diagnosis and facilitate genetic counseling.

[Rapid detection of clarithromycin resistant Helicobacter pylori from children's gastric biopsy specimens by polymerase chain reaction-restriction fragment length polymorphism].

OBJECTIVE: Infection with clarithromycin-resistant Helicobacter pylori (Hp) is often predictive of treatment failure. Susceptibility testing for Hp could guide therapy of Hp infections. However, agar dilution approved by the Clinical and Laboratory Standards Institute (CLSI) to test for antimicrobial susceptibility of Hp is time consuming (results are often not available in a week or more). So a more expeditious method is necessary. The purpose of this study was to evaluate polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) test performed directly on gastric biopsy specimen from children to detect 23S rRNA mutations (A2143G and A2144G) indicating clarithromycin resistance. METHODS: All biopsy specimens were derived from patients presenting with upper gastrointestinal symptoms, submitted to endoscopy in the Affiliated Children's Hospital, Zhejiang University School of Medicine from September 2006 to February 2007. No patients had undergone eradication therapy. Thirty-nine samples randomly selected from positive specimens by rapid urease test, were homogenized in 500 microl brucella broth with 30% glycerol. The 200 microl homogenized fluid was used to purify genomic DNA with the kit according to the instructions provided by manufacturer, and the rest was used to isolate Hp strains by culturing. All the Hp isolates were tested for clarithromycin susceptibility with the agar dilution and classified as resistant if the minimum inhibitory concentrations (MIC) exceeded 1 microg/ml. Simultaneously, PCR-RFLP analysis was performed in order to identify 23S rRNA mutations (A2143G and A2144G). Finally, the two methods were compared by statistics. The agar dilution was used as a standard to determine the sensitivity and specificity of the PCR-RFLP assay. RESULTS: Of the 39 samples, agar dilution and PCR-RFLP method respectively detected 13 (33.3%) and 14 (35.9%) clarithromycin-resistant gastric specimens. The sensitivity and specificity of PCR-RFLP for the detection of Hp in biopsy specimens were both 92%. The positive and negative predictive value was 85.7% and 96% respectively. No statistically significant difference was found between the two methods (chi2=0.06, P>0.05). The rate of Hp resistance to clarithromycin significantly increased compared with a previous report from the authors' hospital in 2004 (chi2=6.20, P<0.05). CONCLUSIONS: Rising clarithromycin resistance rates were observed in children who visited the authors' hospital. PCR-RFLP test is reliable and rapid for detection of clarithromycin resistance directly on gastric biopsy specimen from children and may help choose appropriate antibiotic in Hp eradication therapy.

[Pathogenic effects of primary duodenogastric reflux on gastric mucosa of children].

OBJECTIVE: Duodenogastric reflux (DGR) is a reverse flow of duodenal juice into stomach through pylorus composed of bile acid, pancreatic secretion, and intestinal secretion. The increased entero-gastric reflux results in mucosal injury that may relate not only to reflux gastritis but also esophagitis, gastric ulcers, carcinoma of stomach and esophagus. However, the exact mechanisms of gastric mucosal damage caused by DGR are still unknown. The objective of the present study is to investigate the pathogenic effect of primary DGR on gastric mucosa in children, and to explore the correlation of DGR with clinical symptoms, Hp infection and intragastric acidity. METHOD: Totally 81 patients with upper gastrointestinal manifestations were enrolled and they were graded according to the symptom scores and underwent endoscopic, histological examinations and 24-hour intra-gastric bilirubin was monitored with Bilitec 2000. Of the 81 cases, 51 underwent the 24-hour intra-gastric pH monitoring by ambulatory pH recorder simultaneously. The total fraction time of bile reflux was considered as a marker to evaluate the severity of DGR. The total fraction time of bile reflux was compared between the patients with positive and negative results under endoscopy and histologically, respectively. The correlations of the total fraction time of bile reflux with clinical symptom score, Hp infection, intragastric acidity were analyzed respectively. RESULT: The total fraction time of bile reflux in the patients with hyperemia and yellow stain gastric antral mucosa under endoscopy was significantly higher than that without those changes [17.1% (0.5% approximately 53.2%) vs. 6.5% (0 approximately 58.6%), Z = -1.980, P < 0.05; 19.8% (0.5% approximately 58.6%) vs. 8.8% (0 approximately 38.0%), Z = -2.956, P < 0.01 respectively]. Histologically, the cases with intestinal metaplasia had significantly higher total fraction time of bile reflux than in the cases without intestinal metaplasia [29.0% (1.9% approximately 58.6%) vs. 14.3% (0 approximately 53.7%), Z = -2.026, P < 0.05], but no significant difference was found either between the cases with and without chronic inflammation (P > 0.05) or between the cases with and without active inflammation (P > 0.05). The severity of bile reflux was positively correlated with the score of abdominal distention (r = 0.258, P < 0.05), but no correlation with either the severity of intragastric acid (r = -0.124, P > 0.05), or Hp infection (r = 0.016, P > 0.05) was found. CONCLUSION: Primary DGR could cause gastric mucosal lesions manifested mainly as hyperemia and bile-stained gastric antral mucosa under endoscopy and the gastric antral intestinal metaplasia histologically in children. There was no significant correlation between DGR and gastric mucosal inflammatory infiltration. DGR had no relevance to Hp infection and intragastric acidity. We conclude that DGR is probably an independent etiological factor and might play a synergistic role in the pathogenesis of gastric mucosal lesions along with gastric acid and Hp infection.

[Preliminary study on in-vitro induction of antibiotic resistance in Helicobacter pylori strains isolated from children].

OBJECTIVE: Many clinical studies indicated that Helicobacter pylori (Hp) strains rarely acquired resistance to amoxicillin but easily to clarithromycin and metronidazole. However, it was unclear whether the antibiotic resistance of Hp strains was induced or passively selected during long-term or frequent treatment with metronidazole, clarithromycin and amoxicillin. To compare the propensity of acquired resistance to antibiotics, Hp strains were exposed to amoxicillin, clarithromycin and metronidazole in vitro in this study. METHODS: All Hp strains were clinical isolates, derived from biopsy specimens of patients taken during endoscopy in the Affiliated Children's Hospital, Zhejiang University School of Medicine from December 2004 to July 2005. To seek susceptible strains, the minimum inhibitory concentrations (MICs) of the three antibiotics were determined by using Epsilometer test (E-test) method. In vitro induction was carried out on serially doubling concentrations of antibiotics incorporated into agar. Isolates were also transferred at least three times on antimicrobial agent-free medium, followed by a redetermination of the final MICs to assess the stability of the selected resistance. RESULTS: 7 strains were exposed to antibiotics in vitro. After 6 - 17 passages on antibiotic plates, 7 and 3 strains respectively acquired resistance to metronidazole and clarithromycin, while none of the strains were resistant to amoxicillin. The inductive folds were different among three groups: 8 - 128 folds in metronidazole group; 1 - 256 folds in clarithromycin group; 2 - 16 folds in amoxicillin group. After three transfers on antimicrobial agent-free medium, the MICs decreased significantly in amoxicillin group (P < 0.05) but had no change in metronidazole group and clarithromycin group (P > 0.05). CONCLUSIONS: The metronidazole resistance in Hp was easily selected. Strains resistant to clarithromycin could be selected, but the amoxicillin resistance could not be selected after in vitro induction for Hp isolated from children. The correlation between in vitro and in vivo outcomes suggests that acquired resistance was the main cause for the resistance in Hp strains. The laboratory results of in vitro antibiotic induction could help predict the actual rate of resistance and select appropriate antibiotics for treatment.

[Noncardiac chest pain and gastroesophageal reflux in children].

OBJECTIVE: To investigate the relationship between noncardiac chest pain (NCCP) and gastroesophageal reflux (GER) in children and to assess the diagnostic value of esophageal pH monitoring in patients with NCCP. METHODS: Ambulatory 24 h esophageal pH monitoring was performed in 36 NCCP cases (patient group) with recurrent chest pain and without respiratory diseases and musculoskeletal abnormalities in chest, and 20 of them underwent gastric endoscopy. Eleven of the 20 cases were found to have esophagitis (esophagitis group), while the other 9 cases showed no signs of esophagitis (non-esophagitis group) according to the diagnostic criteria of esophagitis. RESULTS: The episode of esophageal pH < 4, the number of reflux longer than 5 min, the longest reflux time, the percent time of pH < 4 and Boix-Ochoa score in the patient group were 60 +/- 7, 2.44 +/- 0.74, (12.4 +/- 2.8) min, 6.72 +/- 1.39, 24.6 +/- 3.9, respectively, as compared to 33 +/- 4, 0.35 +/- 0.11, (4.3 +/- 0.9) min, 1.25 +/- 0.19, 7.7 +/- 0.9 in the control group. The difference between the two groups had reached significance (t = 3.44, 2.79, 2.73, 3.89, 4.24, respectively, all P < 0.01). The positive rate of acid reflux in the patient group was 58.3% (21/36) whose Boix-Ochoa score higher than 11.99. Eleven of the 20 cases (55.0%) receiving endoscopy were found to have esophagitis, among them the positive rate of GER occurred 81.8% (9/11). Whereas, the other 9 cases (45.0%, 9/20) showed non-esophagitis and the positive rate of GER showed 33.3% (3/9). The number of reflux longer than 5 min and the percent time of pH < 4 in the esophagitis group were 5.8 +/- 2.0, 12.5 +/- 3.5, respectively, as compared to 0.9 +/- 0.5, 3.4 +/- 1.4 in the non-esophagitis group. Significant difference were observed between the two groups (Z = -2.400, -2.545, respectively, all P < 0.05). The episode of esophageal pH < 4, the longest reflux time, and Boix-Ochoa score in the esophagitis group were 73 +/- 11, (26.4 +/- 7.3) min, 41 +/- 10, respectively, as compared to 34 +/- 11, (4 +/- 3) min, 14 +/- 5 in the non-esophagitis group. The difference between the two groups showed significance (Z = -2.926, -2.675, -2.584, respectively, all P < 0.01). CONCLUSIONS: GER is very common in children with NCCP. Esophageal pH monitoring has a therapeutic predictive value in addition to its diagnostic merit for NCCP in children.

[Prevalence of Helicobacter pylori resistant to clarithromycin, amoxicillin and metronidazole in children].

OBJECTIVE: To investigate the prevalence of Helicobacter pylori (Hp) resistant to clarithromycin, amoxicillin and metronidazole in children. METHODS: A total of 44 Hp clinical isolates were cultured from children patients with Hp gastritis and peptic ulcer who underwent gastroscopy during the period from October 2002 to November 2003 in Children's Hospital affiliated to Medical College of Zhejiang University. Nineteen of the patients were girls and 25 boys. The mean age was 8.66 +/- 2.66 years (3 approximately 14 years). The susceptibilities of the 44 Hp strains to clarithromycin, amoxicillin and metronidazole were tested by agar dilution test to determine minimum inhibitory concentration (MIC)(50), MIC(90) and resistance rates were also calculated. RESULTS: Among the 44 Hp strains isolated from children, 8, 4, and 14 strains were resistant to clarithromycin, amoxicillin and metronidazole and the resistant rate was 18.2% (8/44), 9.1% (4/44) and 31.8% (14/44), with MICs for all strains ranging from < 0.125 microg/ml to 64 microg/ml, < 0.125 microg/ml to 64 microg/ml and < 0.125 microg/ml to 128 microg/ml, respectively. MIC(50) and MIC(90) of clarithromycin, amoxicillin and metronidazole were < 0.125 microg/ml, 8 microg/ml; < 0.125 microg/ml, 0.5 microg/ml; 0.5 microg/ml, 128 microg/ml, respectively. The prevalence of Hp resistant to clarithromycin was higher in children than that in adults, while to metronidazole was lower than that in adults with high MICs (32 - 128 microg/ml) and MIC(90) (128 microg/ml) of metronidazole for resistant isolates. Three multidrug resistant strains (6.8%) were simultaneously resistant to these three antibiotics. CONCLUSIONS: The prevalence of Helicobacter pylori resistant to metronidazole was high in children, and the rate of resistance to clarithromycin was higher than that isolated from adults. Amoxicillin-resistant strains were now found, and multidrug resistant strains which resistant to the three antibiotics also emerged.

[Prevalence and mechanism of Helicobacter pylori resistance to clarithromycin in children].

OBJECTIVE: To investigate the prevalence of Helicobacter pylori (H. pylori) resistance to clarithromycin (CLM) in children and to demonstrate the correlation of 23S rRNA gene mutation to clarithromycin resistance of Helicobacter pylori isolates. METHODS: Totally 108 clinical strains of H. pylori were isolated from gastric biopsy specimens obtained from children who underwent endoscopy during the period from October 2002 to January 2004 in Children's Hospital Affiliated to Medical College of Zhejiang University. H. pylori was identified by morphology and biochemical tests after culture. Clarithromycin susceptibility of H. pylori isolates was determined by both E-test and two-fold agar dilution method. A strain was considered resistant when the MIC was defined as >or= 1 microg/ml. Genome DNAs of the 108 isolates were extracted and prepared for PCR to detect the corresponding gene in the V domain of the 23S rRNA. The amplified fragments were recognized and analyzed by restriction fragment length polymorphism (RFLP) when an additional restriction site is created by the mutation. The PCR products of all sensitive and resistant strains were digested with restriction enzyme BbsI and BsaI and were analyzed on a 1.5% agarose gel to discriminate different kinds of mutant genotype. RESULTS: Sixteen of 108 isolates of H. pylori were resistant to clarithromycin by the agar dilution method and E-test method in clinical isolates from children, and the CLM resistance rate was 14.8% (16/108) with MICs ranging from 1 microg/ml to 128 microg/ml. Comparison of results of the two methods showed that these two methods were quite consistent in determination of susceptibility and resistance. The target fragment 425 bp in length containing 23S rRNA corresponding gene was successfully amplified. An A2144G mutation digested with BsaI was detected in 13 resistant isolates, but an A2143G mutation digested with BbsI in only 3 among all 16 clarithromycin resistant strains. None of the sensitive isolates was cleaved by either BsaI or BbsI enzyme, indicating that there was no mutation on them. It was also found that all the fragments from the resistant strains were not completely digested, and 425 bp uncut fragments were also visible and showed three bands indicating that they were heterozygotic strains with a mixture of wild-types and A-->G genotypes. In addition, in this study, no statistically significant difference between mutations at positions 2143 and 2144 with respect to the MIC was observed (r = 0.035, P > 0.05). CONCLUSION: A high prevalence of clarithromycin-resistant H. pylori strains were detected among strains isolated from Chinese children studied. The 23S rRNA gene mutation at positions A2143G and A2144G plays an important role in clarithromycin resistance of H. pylori and A2144G mutation is the predominant finding among the resistant strains.