Studies on antibiotics action on intracellular bacteria

Abstract

The treatment of intracellular pathogens can present difficulties due to the failure of otherwise efficacious antibiotics penetrate into the host cells. In this study, a number of antibiotics were tested in order to determine their effectiveness in killing intracellular Burkholderia pseudomallei or Salmonella Typhimurium. An in vitro intracellular model using a murine macrophage cell line J774.1was used. Against intracellular B.pseudomallei, ciprofloxacin, amoxicillin-clavulanate and piperacillin-tazobactam showed good activity while ceftazidime and meropenem, while decreased in effectiveness, could still be useful as therapy against intracellular B.pseudomallei. Against intracellular S.Typhimurium, the most effective antibiotics were ciprofloxacin and rifampicin. Cefotaxime, ceftriaxone, tetracycline and chloramphenicol were also tested. In general, most antibiotics demonstrated a marked decline in activity against bacteria in the intracellular localisation compared to against extracellular bacteria. Combinations of antibiotics and the interaction of antibiotics with the antimicrobial activity stimulated by IFN-I? pre-stimulation were also tested but no significant synergism was recorded.