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Title: A radiometric assay for bacterial growth detection and quantitative antibiotic testing

Buddemeyer's two-compartment radiometric assay for bacterial growth using respired C-14 carbon dioxide promised major advantages over other available methods, but limitations of the technique have restricted its application. Through a systemic study of relevant physical and chemical factors the authors sought to improve the assay for earlier detection of bacterial growth and to extend its use to measurement of antibiotic drug susceptibility and potency. A 35-fold improvement in count rate response was achieved by a) reversing growth and detector chambers to permit rigorous agitation, b) increasing NaOH quantity and using a supersaturated PPO solution, and c) adding detergent to stabilize NaOH-PPO contact. Bacterial growth may be detected as early as 1/2 hour after inoculation. For rapidly growing bacteria the growth rate constant is defined as the slope of the growth curve (log count rate vs. time). The validity of the growth behavior was verified by measuring growth at several inoculum sizes over 3 orders of magnitude using standard strains of S. aureus and E. coli. The growth rate constant proved to be independent of inoculum size. To test the merit of the system as an antibiotic assay, E. coli were exposed to doses of spectinomycin hydrochloride in the range whichmore » yielded a nonlinear dose-response relation by a turbidity assay. The test, however, showed a linear relation between growth rate constant and antibiotic dose. The results clearly indicate the radiometric growth rate assay to be a rapid, valid and objective assay for bacterial growth and antibiotic sensitivity.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
6842318
Report Number(s):
CONF-840619-
Journal ID: CODEN: JNMEA
Resource Type:
Conference
Resource Relation:
Journal Name: J. Nucl. Med.; (United States); Journal Volume: 25:5; Conference: 31. annual meeting of the Society of Nuclear Medicine, Los Angeles, CA, USA, 5 Jun 1984
Research Org:
Univ. of Iowa, Iowa City, IA
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ANTIBIOTICS; RADIOMETRIC ANALYSIS; SENSITIVITY; ESCHERICHIA COLI; GROWTH; CARBON 14; CARBON DIOXIDE; DOSE-RESPONSE RELATIONSHIPS; GRAPHS; HYDROCHLORIC ACID; INOCULATION; SODIUM HYDROXIDES; TRACER TECHNIQUES; TURBIDITY; ALKALI METAL COMPOUNDS; ANTI-INFECTIVE AGENTS; BACTERIA; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CARBON COMPOUNDS; CARBON ISOTOPES; CARBON OXIDES; CHALCOGENIDES; CHEMICAL ANALYSIS; DRUGS; EVEN-EVEN NUCLEI; HYDROGEN COMPOUNDS; HYDROXIDES; INORGANIC ACIDS; ISOTOPE APPLICATIONS; ISOTOPES; LIGHT NUCLEI; MICROORGANISMS; NUCLEI; OXIDES; OXYGEN COMPOUNDS; QUANTITATIVE CHEMICAL ANALYSIS; RADIOISOTOPES; SODIUM COMPOUNDS; YEARS LIVING RADIOISOTOPES 550701* -- Microbiology-- Tracer Techniques