Determination of Antibiotic Susceptibility of Rickettsia Using the Plaque Assay Technique
FORT DETRICK FREDERICK MD
Pagination or Media Count:
The effect of antibiotic sensitivity discs on plaque formation by various rickettsiae was determined. Twenty-four-hour chick primary monolayers were infected with various rickettsiae and overlayed with agar, upon which commercial antibiotic discs were placed. Plaque formation was completely inhibited by discs impregnated with tetracycline, chloramphenicol, nitrofurantoin, or erythromycin partial inhibition was observed around discs containing nalidixic acid or sulfisoxazole no inhibition was seen around discs containing cephalothin, ampicillin, oxacillin, kanamycin, polymyxin B, streptomycin, or penicillin. This adaptation of the plaque technique should be useful in clinical and diagnostic microbiology and in the evaluation of new antibiotics.