Volume 6, Number 5—October 2000
Research
Toxin Gene Expression by Shiga Toxin-Producing Escherichia coli: the Role of Antibiotics and the Bacterial SOS Response
Patrick T. Kimmitt, Colin R. Harwood, and Michael R. Barer
Table
Induction of stx2 expression by antibiotics under different incubation conditionsa
| Target of action | Incubation conditionsb | ||||||
|---|---|---|---|---|---|---|---|
| Agent (disc content mg/L) | mO2/37 | O2/37 | mO2/42 | AnO2/37 | O2/30 | O2/42 | Zone patternc |
| Background | + | - | - | - | + | - | NA |
| DNA Gyrase | |||||||
| Quinolonesd | + | + | + | + | + | +/- | >MIC |
| Novobiocin (30) | + | - | - | - | + | - | >MIC |
| Folate metabolism | |||||||
| Trimethoprim (5) | + | + | - | + | + | - | >MIC |
| Smx (25) | + | + | - | + | - | - | >MIC |
| DNA | |||||||
| Metronidazole (50) | - | - | - | - | - | - | NA |
| Furazolidone (50) | + | + | - | - | + | - | =MIC |
| Cell envelope | |||||||
| Cephalexin (30) | + | + | - | - | +/- | - | =MIC |
| Amoxycillin (25) | + | + | - | - | - | - | =MIC |
| Amoxy/Clav (20/10) | +/- | - | - | - | - | - | =MIC |
| Ampicillin (10) | + | + | - | - | - | - | =MIC |
| Pip/Taz (10/75) | + | + | - | - | - | - | =MIC |
| Imipenem (10) | - | - | - | - | - | - | NA |
| Aztreonam (30) | + | + | - | - | - | - | =MIC |
| Cefuroxime (5) | + | + | - | - | - | - | =MIC |
| Ceftazidime (30) | + | + | - | - | - | - | =MIC |
| Cefotaxime (30) | + | + | - | - | - | - | =MIC |
| Fosfomycin (200) | - | - | - | - | - | - | NA |
| Polymyxin B (300 IU) | +/- | - | - | - | + | - | =MIC |
| Translation | |||||||
| Gentamicin (10) | - | - | - | - | - | - | NA |
| Chloramphenicol (30) | - | - | - | - | - | - | NA |
| Doxycycline (30) | - | - | - | - | - | - | NA |
| Erythromycin (15) | - | - | - | - | - | - | NA |
| Transcription | |||||||
| Rifampin (25) | - | - | +/- | - | - | - | NA |
aStx2 induction effects (zones of blue coloration, Figure 1): -, not detected, +/-, borderline induction, +, definite induction, >MIC, zone of induction within the zone of growth inhibition; =MIC, induction on the edge of the zone of inhibition; NA, not applicable; Amoxy/Clav, amoxycillin/clavulanic acid; Pip/Taz, piperacillin/tazobactam; Smx, sulphamethoxazole.
bO2, aerobic; mO2 microaerobic; AO2, anaerobic/incubation temperature °C.
cNote: The patterns indicated were detected in three separate experiments and recorded by two independent observers.
dThe quinolones tested are listed in the Materials and Methods section.
