Molecular evaluation of antibiotic susceptibility of Tropheryma whipplei in axenic medium.
OBJECTIVE
Whipple's disease is a rare multisystem chronic infection, involving the intestinal tract as well as various other organs. Tropheryma whipplei is a slow-growing facultative intracellular bacterium that remains poorly understood. In vitro antibiotic susceptibility testing has previously been assessed in cells using a real-time quantitative PCR assay. In this study, we have evaluated the antibiotic susceptibility of three strains of T. whipplei grown in axenic medium using the same assay.


RESULTS
The active compounds in axenic medium were doxycycline, macrolide compounds, penicillin G, streptomycin, rifampicin, chloramphenicol, thiamphenicol, teicoplanin, vancomycin, amoxicillin, gentamicin, aztreonam, levofloxacin and ceftriaxone, with MICs in the range 0.06-1 mg/L. Cefalothin was less active, with MICs in the range 2-4 mg/L. We found that co-trimoxazole was active with MICs in the range 0.5-1 mg/L, and sulfamethoxazole alone was active with MICs in the range 0.5-1 mg/L. MICs of trimethoprim varied from 64-128 mg/L.


CONCLUSIONS
Co-trimoxazole was effective in vitro, but this activity was due to sulfamethoxazole alone. These results were in accordance with the fact that T. whipplei does not contain the encoding gene for dihydrofolate reductase, the target for trimethoprim.
Boulos
A
A
Unité des Rickettsies, CNRS UMR 6020, IFR48, Faculté de Médecine, Université de la Méditerranée, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 05, France.
Rolain
J M
JM
Mallet
M N
MN
Raoult
D
D
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003470:Culture Media; D004353:Drug Evaluation, Preclinical / Q000379:methods; D024881:Drug Resistance, Bacterial / Q000187:drug effects* / Q000502:physiology; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects* / Q000382:microbiology / Q000502:physiology; D008826:Microbial Sensitivity Tests; D008061:Whipple Disease / Q000382:microbiology*
D000900:Anti-Bacterial Agents; D003470:Culture Media