Removal of the antibacterial activity of trimethoprim-sulfamethoxazole, ofloxacin and zidovudine by BACTEC resin-containing blood culture medium.
We determined the capacity of BACTEC resin blood culture media NR 16A and NR 17A to remove the antibacterial activity of trimethoprim-sulfamethoxazole, ofloxacin and zidovudine. Simulated blood cultures containing increasing antibiotic concentrations were inoculated with 10(1), 10(3) and 10(5) CFU/ml blood of various bacterial strains and evaluated with the BACTEC infrared growth detection system. The antibiotic concentrations were adjusted to give breakpoint concentration in the added serum volume or in the total volume of the blood culture vials. Recovery rates and time until detection of bacterial growth in resin-media were compared with those in resin-free media. Trimethoprim-sulfamethoxazole and ofloxacin were, similar to piperacillin, inactivated by resins at antibiotic concentrations that were up to ten times higher than those easily achievable in serum. The antimicrobial effect of zidovudine on gram negative bacteria was reduced in resin media at concentrations corresponding to fifteen times the peak serum levels. Growth of P. aeruginosa, but not of S. aureus, E. coli, K. pneumoniae and Salmonella, was delayed in the presence of resins even at subinhibitory antibiotic concentrations when compared with resin-free media.
Rozdzinski
E
E
Sektion Infektionskrankheiten, Medizinische Universitätsklinik und Poliklinik Ulm.
Kirchner
S
S
Kern
W
W
D016470:Bacteremia / Q000382:microbiology; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D003470:Culture Media; D006801:Humans; D015242:Ofloxacin / Q000494:pharmacology*; D010878:Piperacillin / Q000494:pharmacology; D012116:Resins, Plant; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*; D015215:Zidovudine / Q000494:pharmacology*
D003470:Culture Media; D012116:Resins, Plant; D015215:Zidovudine; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D015242:Ofloxacin; D010878:Piperacillin