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J D MacLowry

Publications and source records attributed to J D MacLowry.

At least 37 records · Page 2Linked to original sources
PubMed1979

Microbiology subsystem of a total, dedicated laboratory computer system.

The computer system used by the Microbiology Service of the Clinical Pathology Department, Clinical Center, National Institutes of Health is discussed. This microbiology subsystem is a part of a dedicated on-line laboratory computer system used by the entire department. The laboratory computer is connected on-line to a hospital computer which provides patient admission, transfer, and discharge data. Mark sense worksheets and cathode ray tube terminals are used for result entry and correction. Cumulative patient reports are printed. Results for both active and completed accessions can be easily retrieved on cathode ray terminals in the laboratory. All laboratory data are archived on magnetic tape from which a research data base and microfiched laboratory records are generated. The manner in which the system is integrated in the routine operation of the microbiology laboratory is emphasized. In addition, some of the costs, benefits, liabilities, and pitfalls associated with the introduction of the computer in the laboratory are reviewed. Finally, we have presented our concept of some of the future enhancements to our present system and some of the directions in which any future microbiology system might develop.

Computers↗
PubMed1978

Evaluation of a dispensing instrument (Dynatech MIC-2000) for preparing microtiter antibiotic plates and testing their potency during storage.

The MIC-2000 96-channel dispenser was evaluated for accuracy and repeatability of dispensing 50-mul volumes of water. It was found to perform within the manufacturer's specifications for accuracy of +/-5%, but not within the limits for repeatability of +/-1%. Overall, instrument performance was found to be satisfactory for the antimicrobial susceptibility testing technique which has been implemented in this laboratory. A method is suggested for simple evaluation of the volumes dispensed. A variety of antibiotics may be stored in Trypticase soy broth in Microtiter plates without loss of potency for periods of at least 2 weeks at -20 degrees C and 4 months at -70 degrees C.

Anti-Bacterial Agents↗
PubMed1977

Development of a lysis-filtration blood culture technique.

A lysed-blood culture system that quickly lyses patients' blood near neutrality and is relatively noninjurious to more delicate pathogens such as Haemophilus influenzae and Bacteroides fragilis is reported. The lysing solution includes culture medium, 0.004 M sodium carbonate and bicarbonate, 0.04% Triton X-100,and 0.6% Rhozyme (a mixture of proteases). Most of the pathogens tested multiplied in the lysing solution. The lysed blood normally is immediately filtered. The membrane is transferred to culture broth. The greatest advantage realized from this blood culture technique is separation of pathogens from antibiotics, bactericidal antibodies, complement, opsonins, and phagocytic systems. Another advantage is the concentration of organisms into a small volume of clear medium for faster growth and visualization of growth. It was observed that both gram-negative and -positive organisms were attracted during filtration to the filter material and were not removed from it by backwashing with buffer. Thus, filter membranes with porosities much larger than would nominally be expected to retain bacteria retained all or part of light and heavy Escherichia coli and Staphylococcus aureus suspensions. Advantage may be taken of this phenomenon to use filters with larger pore sizes and avoid filter clogging by poorly lysed specimens. Porr lysis may result from addition of too much blood to the lysing solution, blood with elevated numbers of erythrocytes or leukocytes, or blood from some people whose blood is naturally more resistant to lysis.

Bacteriological Techniques↗
PubMed1977

Rapid automated disgnosis of bacteremia by impedance detection.

Lysis and filtration of blood culture specimens were combined with impedance detection of bacterial growth to facilitate the diagnosis of bacteremia. A blood lysis-filtration technique (Zierdt et al., 1976) was coupled to a simple, inexpensive automated detection system. The practical and technical aspects of the impedance detection system are discussed. This new blood culturing system was compared to a conventional system for 264 aerobic blood cultures. A 30-ml sample of the blood-broth mixture was withdrawn from the conventional aerobic blood culture bottle and processed in parallel. Excluding the isolation of the commonly recognized contaminants, the detection efficiency was 36% greater in the new system. A total of 53 blood cultures from 107 patients were positive by one or both methods. The new system detected 92% of the total number of positive cultures, compared with 56% detected by the routine method. The explanation of the differences is discussed.

Bacteriological Techniques↗
PubMed1976

Analysis of cost and accuracy of alternative strategies for Enterobacteriaceae identification.

Analysis of the cost of time and material required for the diagnosis of Enterobacteriacea isolates indicated that a conventional 17-tube (20-test) setup costs $7.98 per isolated identified. Using the API 20E, a similar identification cost $3.02. A conventional 7-tube (10-test) setup cost $3.60, whereas the comparable cost by 30% while increasing the number of isolate identified correctly by 3%. Other strategres using the API 20E or a deoxyribounclease test were also evaluated for cost and accuracy.

Bacteriological Techniques↗
PubMed1975

Gentamicin sulfate pharmacokinetics: lower levels of gentamicin in blood during fever.

The effect of fever on serum concentrations and urinary excretion of gentamicin sulfate was studied in humans and dogs. Endotoxin-induced fever in dogs resulted in a decrease of approximately 25% in levels of gentamicin in serum 30 and 60 min after intravenous injection of the antibiotic (1.5 mg/kg) when compared with corresponding afebrile values. In six volunteers with etiocholanolone-stimulated fever, serum concentrations of gentamicin was reduced by an average of 40% in all measurements made 1.2, and 3 hr after intramuscular injection (1.5 mg/kg) as compared with afebrile control values in the same subject. Fever was thought to be the principal factor associated with lower levels of gentamicin, although the half-life of gentamicin in serum and renal clearance of the antibiotic were not significantly affected. These findings emphasize the need for frequent measurements of gentamicin in serum as a guide to adjustment of gentamicin treatment in febrile subjects, and perhaps in all patients receiving the antibiotic.

Adult↗
PubMed1975

Construction of an interpretive pattern directory for the API 10 S kit and analysis of its diagnostic accuracy.

A directory of test patterns and their interpretations has been prepared for identification of Enterobacteriaceae by using the 11-test API 10 S kit. The diagnostic accuracy of the directory and kit were evaluated by using records of test results for 37,476 isolates studied with the 21-test API 20 Enteric kit. Analysis indicates that 96.9% of the isolates would have been correctly identified at the genus level and 95.9% at the species level by using only the subset of tests included in the API 10 S.

Bacteriological Techniques↗
PubMed1975

False-negative stool occult blood tests caused by ingestion of ascorbic acid (vitamin C).

In a female patient with unexplained anemia, ascorbic acid ingestion and apparent false-negative occult blood tests were related. When she stopped ascorbic acid, her stools became strongly reactive ("4+") by three tests for occult stool blood; this association was observed repeatedly. A test developed to measure stool occult blood in the presence of ascorbic acid remained reactive throughout this observation, and the observation was confirmed by in-vitro studies. Current tests for occult blood depend on the pseudoperoxidase activity of heme and are inhibited by low levels of ascorbic acid. Reducing substances chemically similar to ascorbic acid also inhibits occult blood tests; oxidized ascorbic acid and sulfhydryl reducing agents do not inhibit them at physiologic levels.

Ascorbic Acid↗
PubMed1974

Mathematical analysis of the API enteric 20 profile register using a computer diagnostic model.

Results for 21 biochemical tests using the API-20 Enteric kit were obtained from the manufacturer's files for 27,820 bacterial isolates. These isolates were identified by the API Profile Register and also by a computer diagnostic model which estimates the relative likelihoods of various identifications. The computer confirmed the identification in the API Profile Register for 99.36% of the isolates. The manufacturer has reviewed areas of the API Profile Register questioned by the computer analysis; a number of resulting modifications to the API Profile Register have been incorporated in an update letter. This computer model provides a convenient and powerful way to interpret a large number of test results for bacterial identification. This study also demonstrates the use of a large collection of isolates to refine the data matrix used by the diagnostic model.

Bacteriological Techniques↗
PubMed1970

Detailed methodology and implementation of a semiautomated serial dilution microtechnique for antimicrobial susceptibility testing.

The detailed methodology and implementation of a semiautomatic microtechnique for performing serial dilution antimicrobial susceptibility studies are described. Quantitative susceptibility studies to a battery of antimicrobials are performed routinely on all significant clinical isolates. Results are reported as the minimal inhibitory concentration in micrograms per milliliter of broth. Guidelines relating standard doses of antimicrobials with expected blood and urine levels are presented to facilitate the use of the quantitative data. This microtechnique is used to measure serum and other body fluid levels of antimicrobial agents to document the level attained with a specific course of therapy. This technique is highly reproducible and has a high correlation with, and is at least 10 times faster than, standard glass tube techniques.

Anti-Bacterial Agents↗