Standardization of the equine infectious anemia immunodiffusion test and its application to the control of the disease in the United States.

In 1972 the US Department of Agriculture (USDA) established requirements that horses which had immunodiffusion antibody against equine infectious anemia could not be transported interstate. Forty-two states had regulations requiring that horses have a negative equine infectious anemia immunodiffusion test before movement. In order to standardize immunodiffusion testing, it was stipulated in the 1972 regulations that tests must be performed in approved laboratories. The approved laboratories were required to have personnel trained in the immunodiffusion test procedure, to follow the standard protocol, to use licensed reagents, successfully complete proficiency tests, and to report results to federal or state animal health officials. The number of approved laboratories was 160 in June 1983. The number of immunodiffusion tests performed in the United States increased from 82,777 in 1972 to 793,536 in 1977, and has remained at about that level. The percentage of positive samples has decreased from 3.9 in 1972 to 0.6 in 1982. Due to the laboratory standardization program, the reproducibility of test results has been excellent.

Quality control of agar diffusion susceptibility tests: data from the Quality Assurance Service Microbiology program of the College of American Pathologists.

Over a 12-month period, between July 1981 and June 1982, 115 active participants in the Microbiology program of the College of American Pathologists Quality Assurance Service (QAS) submitted a total of 555,619 individual determinations on three quality control reference strains using the NCCLS standardized disc diffusion procedure. Data is presented for those antimicrobic agent/reference strain combinations for which NCCLS control limits have been changed since the last report of QAS microbiology data or that continue to show discrepancies with current NCCLS individual daily test control guidelines. Data for Escherichia coli versus cefoxitin, doxycycline, and nalidixic acid and for Staphylococcus aureus versus cefoxitin, nafcillin, and oxacillin show good compliance with the new NCCLS guidelines and distributions that are all approximately Gaussian. Significant discrepancies were noted for six combinations; cefamandole, cephalothin, neomycin, and nitrofurantoin versus E. coli and amikacin and clindamycin versus S. aureus. Of these discrepancies, only neomycin/E. coli and amikacin/S. aureus can be accounted for by a subpopulation of laboratories, which, when removed, corrects the data.

Quality control of agar diffusion susceptibility tests. Data from the Quality Assurance Service Microbiology Program of the College of American Pathologists.

During the period from January 1979 through January 1981, 155 active participants in the Microbiology Program of the College of American Pathologists Quality Assurance Service (QAS) submitted approximately two million individuals determinations on three quality control reference strains. Of these determinations, 83% were obtained using the standardized disc-diffusion procedure of Bauer and co-workers, and, 6% using the agar overlay modification of Barry and associates. The mean and standard deviation for data obtained using these procedures were similar to those for data collected from the inception of the program in 1974 through December 1978. The number of individual determinations falling above or below existing control limits, however, was significantly less for the present data than for that previously reported. These differences result from a change in computation procedures. In the current report percentages of daily values exceeding the NCCLS limits were calculated using actual counts, whereas in the previous reports these percentages were estimated by accepting an assumption of Gaussian distribution.

Quality control of agar diffusion susceptibility tests. Data from the Quality Assurance Service Microbiology Program of the College of American Pathologists.

From 1974 through December 1978, over 180 laboratories participated in the Microbiology Program of the College of American Pathologists Quality Assurance Service (QAS), submitting a total of 2,372,000 individual antibiotic determinations on three quality control reference strains. Of these determinations, 89.5% were obtained by the standard Bauer-Kirby method; 8.4% by the agar overlay modification of Barry and associates. Standard statistical analysis of data obtained using the agar overlay modification has been reported for each antimicrobic/reference strain combination. Comparisons have been made between the QAS data and those data obtained in earlier collaborative studies, which currently serve as precision and accuracy control limits. In many cases QAS data exceed the existing control limits.

Quality control of agar diffusion susceptibility tests.

Since its beginning in 1974 over 180 laboratories have participated in the Microbiology Program of The College of American Pathologists Quality Assurance Service submitting a total of 2,372,000 individual antibiotic determinations on three quality control reference stains. Eighty-nine and five tenths percent of these determinations were obtained using the standard Bauer-Kirby method; 8.4% using the agar overlay modification of Barry and associates. Standard statistical analysis of data obtained using the Bauer-Kirby method have been reported for each antimicrobic/reference strain combination. Comparisons have been made between the QAS data and those data obtained in earlier collaborative studies which currently serve as precision and accuracy control limits. In many cases QAS data exceed the existing control limits.

Bacteriology of chronic leg ulcers.

The quantitative bacteriology of 13 chronic leg ulcers was sequentially assessed by both swab and biopsy culture techniques, and the effect of either a 10% benzoyl peroxide lotion or placebo lotion was evaluated. There was good correlation between the swab and biopsy culture techniques in 12 of the 17 instances where simultaneous swabs and biopsies were done. Though the benzoyl peroxide did not favorably affect the bacterial flora, ulcer healing did appear to correlate with quantitative bacterial counts. THREE of five ulcers containing fewer than 10(5) organisms per gram of tissue or per centimeter of ulcer surface area healed, while none of eight ulcers containing more than 10(5) organisms healed. Quantitative bacteriological measurements can serve as useful tools in evaluating healing of leg ulcers.