M.: Antibiotic sensitivity of Proteus species

SYNOPSIS A study has been made of the antibiotic sensitivity pattern of 96 strains of Proteus isolated from clinical material and a further 29 strains kindly supplied by Dr. Patricia Carpenter. The results have been analysed in relation to the different species. The effect of electrolytes on the penicillin sensitivity of Proteus species has also been examined. The chemotherapy of infection due to organisms of the Proteus group is often discussed as if the problem were the same for all species and indeed differentiation of the individual species is frequently not recorded in investigations of this nature. In fact the different species show marked differences in antibiotic sensitivity, and the present study was undertaken to investigate the problem more care-fully. Another point which seemed worth investigating was the effect of electrolytes on the antibiotic sensitivity of Proteus species. Both Naylor (1960a) and Sandys (1960) have recommended the use of an electrolyte-deficient medium to prevent the swarming of Proteus. Subsequently Naylor (1960b) reported that strains of Proteus species showed an increased sensitivity to penicillin when tested on such a medium. MATERIALS AND METHODS Ninety-six strains were isolated from specimens sent to a routine clinical bacteriological laboratory and as might be expected the majority of these (82) were strains of Pr. mirabilis; seven were Pr. vulgaris and seven Pr. rettgeri. In addition 12 strains of Pr. morgani, eight of Pr. vulgaris, and nine of Pr. rettgeri were kindly sent t