TABLE 1.
Determination of the MIC and MBC of each β-lactam antibiotic for H. pylori ATCC 43579 and the effects of sub-MICs of these antibiotics on bacterial morphology
| β-Lactam | MIC (μg/ml)a | MBC (μg/ml)a | Morphologiesb |
|---|---|---|---|
| Penicillin G | 0.03–0.06 | 0.03–0.06 | Spheres, blebs |
| Ampicillin | 0.03–0.06 | 0.03–0.06 | Spheres, blebs |
| Amoxicillin | 0.03–0.06 | 0.125–0.5 | Spheres, blebs |
| Oxacillin | 2–4 | 4–8 | Spheres, blebs |
| Mezlocillin | 0.125–0.25 | 0.25–1.0 | Spheres, blebs |
| Cefuroxime | 0.03–0.06 | 0.06–0.5 | Spheres, blebs |
| Ceftriaxone | 0.125–0.25 | 0.125–1.0 | Spheres, blebs |
| Aztreonam | 4–8 | 4–8 | Filaments, spheres, blebs |
MICs of each β-lactam were determined after 24 to 48 h of incubation at 37°C by a microbroth dilution method. MBCs were determined by examination of agar plate subcultures after 72 h of incubation at 37°C (see Materials and Methods for details). The data shown are averages of three separate experiments.
Morphologies of H. pylori were observed between 24 and 48 h of incubation at 37°C in the presence of antibiotic concentrations equal to one-half to one-fourth of the MIC. Although they are not listed here, some residual normal-appearing helical or rod forms were also present in each culture.