An electronmicroscope study of the effect of sulphadiazine and trimethoprim on Enterobacter cloacae.
Electronmicroscopy of thin sections of log phase cells of Enterobacter cloacae NCTC 10005 grown for 4 h in the presence of sulphadiazine 250 micrograms/ml, trimethoprim 12.5 microliters/ml or the combination of sulphadiazine 250 micrograms/ml plus trimethoprim 12.5 micrograms/ml indicated that both agents caused marked morphological damage even though the MIC of sulphadiazine for the E. cloacae strain was > 3000 micrograms/ml. The damage took the form of electron-transparent areas devoid of ribosomes in the cytoplasm and detachment of the outer membrane. The latter was most marked with trimethoprim, which also caused damage to the cytoplasmic membrane. It is postulated that the synthesis of the peptidoglycan layer was affected by the antimetabolites since the morphological effects were strikingly similar to those caused by treatment of E. cloacae with disodium edetate plus lysozyme. Viable counts of cultures undergoing the same treatments as those prepared for electronmicroscopy indicated that although sulphadiazine merely partially inhibited growth it nevertheless enhanced the bactericidal action of trimethoprim over a 5-h period.
Richards
R M
RM
School of Pharmacy, Robert Gordon University, Schoolhill, Aberdeen.
Xing
J Z
JZ
Gregory
D W
DW
Marshall
D
D
D002462:Cell Membrane / Q000187:drug effects; D015169:Colony Count, Microbial; D004347:Drug Interactions; D004352:Drug Resistance, Microbial; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000648:ultrastructure; D008854:Microscopy, Electron; D012270:Ribosomes / Q000187:drug effects; D013411:Sulfadiazine / Q000494:pharmacology*; D014295:Trimethoprim / Q000494:pharmacology*
D013411:Sulfadiazine; D014295:Trimethoprim