Abstract

Two isolates of Proteus mirabilis and four of Esch. coli which would not grow on commonly used commercial sensitivity test media are reported. These organisms appear to be resistant to co-trimoxazole, are exacting towards thymidine, and five of six were isolated from patients who had been treated with co-trimoxazole. A method for the detection of these strains is given and their significance in the laboratory and clinical practice discussed.