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Biomedical subjects

D C Shanson

Publications and source records attributed to D C Shanson.

At least 19 recordsLinked to original sources

Serum gentamicin assays of 100 clinical serum samples by a rapid 40 degrees C. Klebsiella method compared with overnight plate diffusion and acetyltransferase assays.

We have compared the results of gentamicin assay of 100 clinical serum samples by a rapid 40 degrees C plate diffusion method, an overnight plate assay at 37 degrees C, and radioactive acetyltransferase methods. The results of assay obtained by both plate diffusion methods agreed closely. There was excellent correlation between the results of acetyltransferase and plate assays provided that human serum gentamicin standards were used for the acetyltransferase assay and turbid sera were excluded. Lipaemic sera were associated with falsely high results by the acetyltransferase method. There was no difference in specificity between the methods when antibiotics other than gentamicin were present. Much less skilled technician time was required to perform the rapid 40 degrees C plate method than the radioactive acetyltransferase method. The 40 degrees C plate method is preferred for routine serum gentamicin assays in our clinical laboratories.

Acetyltransferases

Outbreak of hospital infection with a strain of Staphylococcus aureus resistant to gentamicin and methicillin.

A previously unreported strain of Staphylococcus aureus, resistant to both gentamicin and methicillin, as well as other antibiotics, caused an outbreak of hospital infection involving 17 patinets and 8 staff. In this outbreak none of the patients had received previous aminoglycoside therapy. The epidemic strain was eliminated by the use of strict measures for the control of infection.

Cross Infection

Rapid microbiologic assay of tobramycin.

Different, rapid, plate diffusion assays of tobramycin in serum were compared with each other and with an overnight assay. These assays were done with Klebsiella edwardsii var. atlantae, which was resistant to many antibiotics. One of the rapid assays of tobramycin tested used a 1:50-1:100 dilution of an overnight culture, and results were recorded after incubation for 5 hr at 35 C. Two shorter assays were also tested with a 1:10 dilution of an overnight assay. The 5-hr assay was as reproducible and as accurate as the overnight assay. The 2.5-hr assay at 35 C proved to be an inaccurate method. Incubation of the assay at 40 C instead of 35 C resulted in more rapid growth of K. edwardsii and in the production by tobramycin of larger and sharper zones of inhibition. The 2.5-hr assay at 40 C was as reproducible and as accurate as the 5-hr and the overnight assays.

Animals

A new selective medium for the isolation of Salmonellae other than Salmonella typhi.

A medium consisting of a MacConkey's base with added magnesium, calcium, cobalt, zinc, thiosulphate, novobiocin, iron dextran, Tween 80 and EDTA has been found highly selective for Salmonellaparatyphi B and most of the food poisoning salmonellae that commonly occur in Britain. Nearly all the normal faecal flora is inhibited.

Bacteriological Techniques