Effects of ampicillin, ceftriaxone, chloramphenicol, pefloxacin and trimethoprim-sulphamethoxazole on Salmonella typhi within human monocyte-derived macrophages

J Antimicrob Chemother. 1990 Nov;26(5):689-94. doi: 10.1093/jac/26.5.689.


The killing effect of various antimicrobial agents used in the therapy of Salmonella typhi infection was tested against Salm. typhi strain Ty2 after phagocytosis by human monocyte-derived macrophages. The macrophages, cultured in 96-well microtitre plates, were infected for 1 h at 37 degrees C by opsonized Salm. typhi Ty2 at a bacteria-cell ratio of 9:1. When added to the infected macrophage monolayers, at one and ten times the MIC, ampicillin, ceftriaxone and pefloxacin appeared to be highly bactericidal (less than 0.25 log10 cfu/well after 20 h, against 4 log10 cfu/well in antibiotic-free controls). Trimethoprim-sulphamethoxazole was bactericidal at ten times the MIC, but not at the MIC. Chloramphenicol was mostly bacteriostatic at the concentrations tested. As a control, gentamicin (10 mg/l) did not exhibit any significant antibacterial effect, indicating that most or all the bacteria recovered from lysed cells were intracellular. Other controls for phagocytosis were also performed with heat-killed Candida albicans. Our results seem to correlate with the known clinical effect of some antimicrobials in human Salm. typhi infection. The in-vitro assay described here may be useful for assessing the activity of antimicrobial agents against Salm. typhi infection.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ampicillin / pharmacology
  • Anti-Bacterial Agents / pharmacology*
  • Ceftriaxone / pharmacology
  • Chloramphenicol / pharmacology
  • Humans
  • In Vitro Techniques
  • Macrophages / drug effects
  • Macrophages / microbiology
  • Pefloxacin / pharmacology
  • Salmonella Phages
  • Salmonella typhi / drug effects*
  • Trimethoprim, Sulfamethoxazole Drug Combination / pharmacology
  • Trypan Blue


  • Anti-Bacterial Agents
  • Pefloxacin
  • Chloramphenicol
  • Ceftriaxone
  • Ampicillin
  • Trimethoprim, Sulfamethoxazole Drug Combination
  • Trypan Blue