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- Gel electrophoresis UV camera (Bio-Rad).
- A colonizing E. coli: Here, A clinical blood isolate of E. coli,
lineage B2-O25b-ST131 (see Note 8). - Colorimeter 254, 546 nm (Sherwood).
- Multiplex PCR kit (Qiagen).
- Primers 1283 (GCGATCCCCA) (TAG Copenhagen).
- Primer 1247 (AAGAGCCCGT) (TAG Copenhagen).
- 2% E-gels, 48 wells (Invitrogen).
- 1 kb DNA ladder (Fermentas).
- Positive control for RAPD PCR: E. coli ATCC 25922 (Oxoid).
- A PCR cycler (e.g., Applied Biosystems).
- Antibiotics for treatment of the mice, dissolved in 0.9% saline
to appropriate concentration. - 2 g Ampicillin (Bristol-Myers Squibb,), daily dose: 1.5 mg/
mouse. - 1 g Cefotaxime (Fresenius-Kabi), daily dose: 2 mg/mouse.
- 1.5 g Cefuroxime (Fresenius-Kabi), daily dose: 4 mg/mouse.
- 1 g Meropenem (Hospira), daily dose: 1.5 mg/mouse.
- 2 mg/mL Ciprofloxacin (Fresenius-Kabi), daily dose: 0.5 mg/
mouse. - 1 g Diclocil (Bristol-Myers), daily dose: 2 mg/mouse.
- 1 g Selexid (Leo-Pharma), daily dose: 2 mg/mouse.
- 150 mg/mL Clindamycin (Stragen), daily dose: 1.4 mg/
mouse. - 5 mg/mL Metronidazole (Baxter), daily dose: 2.5 mg/mouse.
Agar containing antibiotics should be stored at 4–5 °C and
kept in darkness to avoid untimely decomposition of antibiotics.
3 Methods
- Mice are brought into the stable 4–7 days prior to investiga-
tion. In the stable they are divided into pairs of two per cage
and two cages belong to one group; thus, one antibiotic is
given to a total of four mice. The study is conducted from day
1 to day 8. All cages are changed daily. At the end of day 8 all
mice are sacrificed (see Notes 4– 7 ). - On day zero, culture the colonizing pathogen (CP) on suitable
agar plates (see Notes 8 and 9 ). - On day 1
3.1 Mouse
Experiments
Frederik Boëtius Hertz et al.