[Microbiological factors that influence the eradication of Helicobacter pylori in adults and children].
OBJECTIVE
To study microbiological factors of Helicobacter pylori, such as antimicrobial susceptibility and virulence, which affect the eradication of the microorganism in gastric mucosa of adult and pediatric patients.


METHODS
Fifty-five H. Pylori strains were isolated from culture of biopsy specimens from 39 adult and 16 pediatric patients. Antibiotic susceptibility was determined by agar dilution and study of virulence factors (cagA gene and alleles s1 and s2 of the vacA gene) by PCR. Outcome of treatment with amoxicillin (AMX), clarithromycin (CLR) and omeprazole was assessed by the urea breath test. We studied the relation of minimum inhibitory concentration (MIC) of AMX and CLR and presence of virulence factors with eradication of the microorganism.Results. The eradication rate was 69% (38/55), 71.7% in adults and 62.5% in children. Resistance to CLR and AMX was 14.5% and 0%, respectively. Overall eradication rates with respect to the variables studied were: 75% and 53% in strains with AMX MICs of < or = 0.01 6mg/L and > or = 0.032 mg/L (range < or = 0.008-0.5) (p > 0.05), 79% and 12% in strains with clarithromicina MICs of < 1 mg/L and > or = 1mg/L (range # 0.008-64) (p < 0.05), 79% and 54% in cagA+ and cagA strains (p > 0.05) and 82% and 62% in s1 and s2 strains (p > 0.05), respectively.


CONCLUSIONS
H. pylori strains with higher amoxicillin and clarithromycin MICs, and cagA and vacA s2 strains were related with lower rates of eradication in both adult and pediatric populations treated with amoxicillin, clarithromycin and omeprazole.
Domingo
Diego
D
Servicio de Microbiología. Hospital Universitario de La Princesa. Madrid. España. ddomingo@helicobacterspain.com
Alarcón
Teresa
T
Vega
Alba Edith
AE
García
José Angel
JA
Martínez
María Josefa
MJ
López-Brea
Manuel
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000627:therapeutic use*; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D017291:Clarithromycin / Q000627:therapeutic use*; D004351:Drug Resistance; D004359:Drug Therapy, Combination / Q000627:therapeutic use*; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000453:epidemiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use*; D014774:Virulence
D000897:Anti-Ulcer Agents; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D000658:Amoxicillin; D017291:Clarithromycin; D009853:Omeprazole