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Biomedical subjects

M I de Silva

Publications and source records attributed to M I de Silva.

7 recordsLinked to original sources
PubMed1986

Cost effectiveness of the antibiotic removal device for processing blood cultures.

The antimicrobial removal device (ARD) blood culture system has been reported to increase the sensitivity of isolation of pathogenic microorganisms in bacteremic patients who are already on antibiotics. To determine the usefulness of this system to the clinician for the diagnosis of bacteremia and to determine the additional cost incurred by the use of the system, the microbiological results at two hospitals over a period of two years were compared. A total of 25,124 standard blood cultures (SBC) were performed with a positive culture rate of 10.7 percent. Of the 858 specimens processed by ARD alone, 68 (7.9 percent) were positive. There were a total of 2,657 specimens from 910 patients that were processed simultaneously using both systems. Both ARD and SBC were negative in 2,249 specimens, and 290 blood cultures from 107 patients grew the same organism using both systems. Thirty-one specimens from 12 patients grew pathogenic bacteria from ARD bottles; in each the SBC culture was negative. However, in 21 patients (44 specimens) bacteremia was detected only in SBC with negative cultures from ARD bottles.Thus, in the vast majority of the cases, SBC alone was sufficient to detect bacteremia, even in the patient with recent or concomitant antibiotic therapy. The total processing cost was calculated for the cases in which SBC and ARD were performed simultaneously and was found to be $6,588 for SBC and $15,005 for ARD. The comparative cost per bacteremic patient detected by the two methods was $46.40 for SBC and $555.75 for ARD.

Bacteria↗
PubMed1983

Detection of beta lactamase producing bacteria by Cefinase: comparison with three other methods.

Nine hundred and sixty-seven strains of gram positive and gram negative bacteria were tested for the production of beta lactamase by Cefinase and the results were compared with acidometric microtiter, disc diffusion and antibiotic dilution procedures. A total of 420 strains of bacteria had a minimal inhibitory concentration (MIC) of more than 2.0 micrograms/ml for penicillins. They consisted of 23 strains of Neisseria gonorrhoeae, 36 of Haemophilus influenzae, 188 of Staphylococcus aureus and 173 strains of S. epidermidis. All the penicillin resistant strains gave positive results for beta-lactamase with Cefinase and acidometric method within 60 min. All the 547 strains of penicillin sensitive bacteria (MIC less than or equal to 2.0 micrograms/ml) were negative for beta-lactamase production by both methods.

Bacteriological Techniques↗
PubMed1977

Multiple biotypes of Klebsiella pneumoniae in single clinical specimens.

The occurence of multiple biotypes of Klebsiella pneumoniae within single specimens was determined in 59 clinical specimens. Biotyping was performed on five colonies of K. pneumoniae from each specimen, using the API 20E system (Analytab, Inc., New York) for identification of Enterobacteriaceae with strict adherence to the manufacturer's instructions. Multiple biotypes of K. pneumoniae were present in 31% (18) of the clinical specimens. Twenty-eight colonies representative of specimens with single and multiple biotypes were tested further for biotype reproducibility. Whereas genus and species identification was 100% reproducible, variation of one or more biochemical tests on serial transfers resulted in biotype reproducibility of only 64%. The greatest variation in biochemical tests occurred with urease (14%), indole production (10%) and citrate utilization (9%). Multiple biotypes in single specimens appear to be due to both inherent differences among the colonies in the specimen and variability in the system used to determine biochemical reactions. The presence of multiple biotypes limits the usefulness of biochemical typing for epidemiological surveilance of K. pneumoniae.

Humans↗