gh organisms with MICs > 0.25 mcg/mL to determine a resistance breakpoint.
Clarithromycin MIC (mcg/mL)*
Interpretation
≤ 0.25
Susceptible(S)
0.5
Intermediate(I)
≥1.0
Resistant(R)
Amoxicillin MIC (mcg/mL)*†
Interpretation
≤ 0.25
Susceptible(S)
There were not enough organisms with MICs > 0.25 mcg/mL to determine a resistance breakpoint.
Clarithromycin MIC (mcg/mL)*
Interpretation
≤ 0.25
Susceptible(S)
0.5
Intermediate(I)
≥1.0
Resistant(R)
Amoxicillin MIC (mcg/mL)*†
Interpretation
≤ 0.25
Susceptible(S)
Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard clarithromycin and amoxicillin powders should provide the following MIC values:
Table 9
*
These are quality control ranges for the agar dilution methodology and they should not be used to control test results obtained using alternative methods.
Microorganism
Antimicrobial Agent
MIC (mcg/mL) *
H.pylori ATCC 43504
Clarithromycin
0.016 − 0.12 (mcg/mL)
H.pylori ATCC 43504
Amoxicillin
0.016 − 0.12 (mcg/mL)
These are quality control ranges for the agar dilution methodology and they should not be used to control test results obtained using alternative methods.
Microorganism
Antimicrobial Agent
MIC (mcg/mL) *
H.pylori ATCC 43504
Clarithromycin
0.016 − 0.12 (mcg/mL)
H.pylori ATCC 43504
Amoxicillin
0.016 − 0.12 (mcg/mL)
Effects on Gastrointestinal Microbial Ecology: Decreased gastric acidity due to any means, including proton pump inhibitors, increases gastric counts of bacteria normally present in the gastrointestinal tract. Treatment with proton pump inhibitors may lead to slightly increased risk of gastrointestinal infections such as Salmonella and Campylobacter and possibly Clostridium difficile in hospitalized patients.
13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
The carcinogenic potential of NEXIUM was assessed using studies of omeprazole, of which esomeprazole is an enantiomer. In two 24-month oral carcinogenicity studies in rats, omeprazole at daily doses of 1.7, 3.4, 13.8, 44, and 141 mg/kg/day (about 0.7 to 57 times the human dose of 20 mg/day expressed on a body surface area basis) produced gastric ECL cell carcinoids in a dose-related manner in both male and female rats; the incidence of this effect was markedly higher in female rats, which had higher blood levels of omeprazole. Gastric carcinoids seldom occur in the untreated rat. In addition, ECL cell hyperplasia was present in all treated groups of both sexes. In one of these studies, female rats were treated with 13.8mg omeprazole/kg/day (about 5.6 times the human dose on a body surface area basis) for 1 year, then followed for an additional year without the drug. No carcinoids were seen in these rats. An increased incidence of treatment
