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Biomedical subjects

J W Messer

Publications and source records attributed to J W Messer.

9 recordsLinked to original sources
PubMed1998

A rapid, specific membrane filtration procedure for enumeration of enterococci in recreational water.

A two-step membrane filter (MF) method with mE medium, upon which the membrane must be incubated for 48 h and then transferred to a substrate medium to differentiate enterococci, is recommended by the U.S. Environmental Protection Agency to measure enterococci in fresh and marine recreational waters. The original mE medium was modified by reducing the triphenyltetrazolium chloride from 0.15 to 0.02 g/liter and adding 0.75 g of indoxyl beta-D-glucoside per liter. The new MF medium, mEI medium, detected levels of enterococci in 24 h comparable to those detected by the original mE medium in 48 h, with the same level of statistical confidence. In addition, the use of mEI medium eliminated the need to transfer the membrane to a substrate medium to differentiate enterococci from other genera of the fecal streptococcal group. Colonies from mEI medium were examined to determine the rates of false-positive and false-negative occurrences. mEI medium had a false-positive rate of 6.0% and a false-negative rate of 6.5%. Interlaboratory testing of the MF method with mEI medium demonstrated that the relative reproducibility standard deviations among laboratories ranged from 2.2% for marine water to 18.9% for freshwater. The comparative recovery studies, specificity determinations, and multilaboratory evaluation indicated that mEI medium has analytical performance characteristics equivalent to those of mE medium. The simplicity of use and decreased incubation time with mEI medium will facilitate the detection and quantification of enterococci in fresh and marine recreational waters.

Culture Media↗
PubMed1995

Occurrence of high-level aminoglycoside resistance in environmental isolates of enterococci.

High-level resistance to aminoglycosides was observed in environmental isolates of enterococci. Various aquatic habitats, including agricultural runoff, creeks, rivers, wastewater, and wells, were analyzed. Strains of Enterococcus faecalis, E. faecium, E. gallinarum, and other Enterococcus spp. demonstrated multiple antibiotic resistance patterns to aminoglycosides.

Aminoglycosides↗
PubMed1982

Bacillus stearothermophilus disc assay for detection of inhibitors in milk: collaborative study.

A 2-part (A and B) collaborative study was conducted on a Bacillus stearothermophilus paper disc (12.7 mm) method to detect residual inhibitors in milk. The 18 participating collaborators assayed raw milk samples spiked with a beta-lactam (penicillin G). Of the 18 collaborators, 14 participated in part A and 16 in part B. Part A demonstrated that either Antibiotic Medium No. 4 or PM Indicator Agar is suitable for use in the assay. The lowest concentration detectable, not significantly different from 100% at the alpha = 0.05 level, was 0.008 unit/mL with either medium. Part B demonstrated that the sensitivity of the method is equal to that of the current AOAC method (16.131-16.136). The concentration of beta-lactam detected by 50% of the analysts was 0.003-0.005 unit/mL in this study, compared with 0.005 unit/mL reported in an earlier collaborative study on the current AOAC method. No false positive results were reported in part A or part B. All samples found positive by the confirmatory test in part B were correctly identified as a beta-lactam with commercial Penase discs. The lowest concentration detectable by the method, not significantly different from 100% at the alpha = 0.05 level, was 0.008 unit/mL. The method was adopted official first action.

Animals↗
PubMed1978

The predictive value of myocardial perfusion scintigraphy after stress in patients without previous myocardial infarction.

Seventy-five patients who had chest pain but no history or ECG evidence of myocardial infarction (MI) underwent myocardial-stress perfusion scintigraphy (MSPS) with thallium-201, treadmill-stress testing (TST), and coronary cineangiography (CA). The sensitivities of MSPS and TST for coronary stenosis greater than or equal to 75% were 68% and 71%, respectively; their specificities were 97% and 79%, respectively (0.1 greater than p greater than 0.05). When the character of a patient's chest pain is considered, Bayesian analysis leads to the following conclusions: (a) MSPS can be useful in pre-CA screening of patients with chest pain but no MI if their pain is thought to be of uncertain or nonischemic origin: (b) the sensitivity of Tl-201 MSPS is not sufficient for pre-CA screening of patients without MI who have typical or atypical angina pectoris; (c) the sensitivity of MSPS would have to be approximately 95% in order for the test to be useful in pre-CA screening of patients who have atypical angina pectoris; (d) MSPS may be superior to TST in these applications; and (e) it is not clear that there is any advantage in combining MSPS and TST into a single screening test rather than using MSPS alone.

Cineangiography↗
PubMed1975

Direct plating method for enumeration of Staphylococcus aureus: collaborative study.

Considerable evidence has been published regarding the adverse effect of sodium chloride on physiologically impaired cells of Staphylococcus aureus, such as are to be expected in processed foods. A direct plating method for enumeration of S. aureus eliminating the use of sodium chloride was devised and subjected to collaborative study by 16 analysts. Results obtained by the direct plating method were compared to those obtained by the AOAC official first action method (46.036--46.040). Participating analysts examined duplicate samples at population levels of 91, 34, and 20 S. aureus/g. Coefficients of variation among analysts were considerably lower for the direct plating method (31, 81, and 48%, respectively) than for method 46.040 (59, 156, and 150%, respectively) at all 3 population levels. High coefficients of variation for the direct plating method at 2 of the 3 levels were due principally to low populations of S. aureus. The direct plating method has been adopted as official first action for general purpose use and use of method 46.036--46.040 has been restricted to raw food ingredients and nonprocessed foods.

Culture Media↗