Prevalence and rapid identification of clarithromycin-resistant Helicobacter pylori isolates in children.
BACKGROUND
Little is known about the prevalence of antibiotic-resistant Helicobacter pylori infection in children. Culture and antimicrobial susceptibility testing are generally time-consuming and not a routine in many hospitals.


OBJECTIVE
To investigate the prevalence of clarithromycin-resistant H. pylori strains in children, to identify those isolates via rapid methodology and to examine the severity of gastritis caused by the antibiotic-resistant H. pylori isolates.


METHODS
Enrolled were 245 children investigated for H. pylori infection by endoscopic examination. The gastric antral specimens were subjected to DNA extraction and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with primers specific to the H. pylori 23S rRNA gene. Conventional bacterial cultures were performed simultaneously as the diagnostic standard. Minimal inhibitory concentrations of clarithromycin and metronidazole were determined by E test. This was used as a standard to determine the sensitivity and specificity of the above PCR-RFLP assay. The specimens were processed for histologic examination and evaluated by the updated Sydney system.


RESULTS
H. pylori was isolated in 67 of the 245 children; 12 (18%) of them were clarithromycin-resistant and 6 (9%) were metronidazole-resistant. No difference in histologic examinations was noted between the antibiotic-resistant and -susceptible strains. We performed PCR-RFLP with all 12 clarithromycin-resistant isolates: 10 had a 23S ribosomal RNA A2144G point mutation; 1 had a mixture of an A2143G point mutant and susceptible strains; and 1 had neither of the 2 mutations.


CONCLUSIONS
The prevalence of clarithromycin-resistant H. pylori isolates in Taiwanese children is 18%. PCR-RFLP had a high sensitivity (92%) and specificity (100%) for the clarithromycin resistance gene mutation determination. The dominant mutation is A2144G. PCR-RFLP provides a rapid and accurate approach to detect clarithromycin-resistant strains within 24 h.
Yang
Y J
YJ
Department of Pediatrics, National Taiwan University, College of Medicine and Hospital, Taipei.
Yang
J C
JC
Jeng
Y M
YM
Chang
M H
MH
Ni
Y H
YH
D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002648:Child; D017291:Clarithromycin / Q000627:therapeutic use*; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial / Q000235:genetics; D005260:Female; D005756:Gastritis / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology*; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012720:Severity of Illness Index
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017291:Clarithromycin