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W O Schalla

Publications and source records attributed to W O Schalla.

At least 19 recordsLinked to original sources
PubMed2001

Viral load test reports: a description of content from a sample of US laboratories.

CONTEXT: Human immunodeficiency virus (HIV) RNA testing (viral load testing) is increasingly important in the care of patients infected with HIV-1 to determine when to initiate, monitor, and change antiretroviral therapy. Patient viral load testing information is communicated to the clinician through the laboratory test report. OBJECTIVES: To examine the format and information used in reporting viral load testing results and determine the clarity of the information provided in these reports. DESIGN: Patient test reports with all personal identifiers removed were requested of viral load testing laboratories participating in a telephone survey of laboratory practices. Hospital, independent, health department, and "other type" laboratories identified as university-associated laboratories participated in the telephone survey. RESULTS: Thirty-seven unique test reports were collected. All laboratories reported results in copies/mL, while 14% also reported results as "log(10) copies/mL." The test kit was identified by only 24% of the laboratories. Reportable ranges were specified by 70% of the laboratories, but there was considerable variation in terminology. One laboratory reported a viral load copy number below the manufacturer's test kit lower limit of sensitivity. The layout and format differed among reports. Some results were expressed in log(10), others contained nonsignificant integers, while others contained exponential numbers. Supplemental information in some reports included previous patient test results and significance of changes from baseline. The format of some reports made it difficult to read the report information and interpret the testing results. CONCLUSION: This study emphasizes the importance of standardizing the reporting of HIV-1 viral load test results to minimize result misinterpretation and incorrect treatment.

Data Collection↗
PubMed2000

Laboratory performance in HTLV-I/II analysis.

BACKGROUND: Since 1989, the CDC's Model Performance Evaluation Program has shipped samples to voluntary participant laboratories that test for HTLV antibodies. Each laboratory tests the well-characterized samples, reports the results, and provides information about its testing practices. The data from 15 performance survey periods are reported here. STUDY DESIGN AND METHODS: Multiple logistic regression was used to analyze all data from 15 survey periods from 1989 through 1996. RESULTS: The mean analytic sensitivity for EIA was 99.2 percent per survey period (range, 96-100%), the mean analytic specificity was 97.8 percent (75.6-100%), and the overall accuracy was 88.8 percent (63.8-100%). The mean analytic sensitivity for Western blot was 88.8 percent (75.6-100%); the mean analytic specificity was 95.7 percent (86.7-100%), and the overall accuracy was 91.1 percent (78.1-100%). CONCLUSIONS: Statistical analyses suggested associations between performance and both the retroviral serologic status of the sample and the analytical testing method. Western blot accuracy was associated with weekly testing volume. In early survey periods, performance problems were noted in the analysis of samples from donors with concomitant HTLV and HIV infections and those from donors who were positive for HTLV-II. Technological developments in test methods, such as the addition of recombinant antigens, appeared to have improved the laboratory performance of specific testing methods.

Blotting, Western↗
PubMed1998

Impact of quality control on accuracy in enzyme immunoassay testing for human immunodeficiency virus type 1 antibodies.

OBJECTIVE: To assess use of quality control (QC) material, supplemental to internal kit controls (calibrators), as protection against errors in enzyme immunoassay testing for human immunodeficiency virus type 1 antibodies. DESIGN: From August 1994 to January 1996, enzyme immunoassay testing accuracy was assessed for laboratories participating in the Centers for Disease Control and Prevention Model Performance Evaluation Program that provided information regarding their use of QC material. Error rates were examined for human immunodeficiency virus type 1 antibody-negative, strongly positive, and weakly positive samples. RESULTS: The overall error rate with QC (2.20%) was significantly (P = .0023) lower than the error rate without QC (2.90%). With QC use there was a significant reduction in the relative risk of error for negative (P = .014) and weakly positive (P = .0067) samples. After multivariate analysis, use of QC lowered overall error rate by 29% (P = .0009). Laboratories not using QC were at increased risk of systematic error. Following the Clinical Laboratory Improvement Amendments of 1988 guidelines for QC material was relatively more protective against error than lower frequencies/number of levels. CONCLUSIONS: Using QC protected against errors in enzyme immunoassay testing for human immunodeficiency virus type 1 antibodies. Two levels of QC should be used with each run as mandated by the Clinical Laboratory Improvement Amendments of 1988.

Clinical Laboratory Techniques↗
PubMed1997

Quality assessment activities in Latin America and the Caribbean.

The Pan American Health Organization (PAHO) supports performance evaluation programs in clinical chemistry, Caribbean. Much more work remains to be done before many labs in this part of the world can be certified as providing accurate results, but PAHO has taken an important first step toward establishing benchmarks and rallying for labs to improve test quality.

Caribbean Region↗
PubMed1993

Quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. Identification of variables associated with laboratory performance.

To identify factors that may affect the quality of laboratory performance of human immunodeficiency virus type 1 (HIV-1) antibody testing, the Centers for Disease Control and Prevention Model Performance Evaluation Program surveyed laboratories in 1989 that performed enzyme immunoassay (EIA) and Western blot tests for HIV-1 antibody. Panels of 10 HIV-1-antibody-positive and antibody-negative plasma samples, some of which were duplicates, were mailed to program-participating laboratories. Laboratories were also mailed survey questionnaires to ascertain their laboratory characteristics and testing practices. Using 1988 data, researchers previously found that the overall analytic performance of laboratories performing HIV-1 antibody testing was independently associated with the following: (1) requiring a minimum degree of testing personnel; (2) having written criteria for identifying unsatisfactory specimens; (3) requiring in-house training for testing personnel; (4) having tested more than 10,000 specimens; (5) being identified as an "other" laboratory type; (6) having more than 24 months of testing experience; (7) laboratory uses specific (Abbott) materials for EIA; and (8) testing specimens collected by family-planning clinics. To verify these findings, we performed multivariate analysis on 1989 performance data. For the 1989 EIA analytic sensitivity, significant positive (P < or = .05) associations were detected with having written criteria for identifying unsatisfactory specimens and with having tested more than 10,000 specimens. For the 1989 overall EIA analytic performance, a significant negative (P < or = .05) association was found with using specific (Abbott) EIA materials, and a significant positive (P < or = .05) association was found with having tested more than 10,000 specimens. For Western blot results, the only significant (P < or = .05) associations were for both analytic sensitivity and overall analytic performance and having tested more than 10,000 specimens.

Blotting, Western↗
PubMed1993

Variability of reporting and lack of adherence to consensus guidelines in human T-lymphocyte immunophenotyping reports: results of a case series.

Percentages and absolute counts of CD4+ lymphocytes, as determined by T-lymphocyte immunophenotyping (TLI), are prognostic, as well as diagnostic, of the course of human immunodeficiency virus type 1 infections and are important indicators for initiating Pneumocystis carinii pneumonia prophylaxis and antiretroviral therapy. In December 1990, we requested that a nonrandom sample of 17 laboratories provide us with typical reports of their TLI results from an immunodeficient patient and from a patient whose TLI results were within the laboratory's normal reference ranges. We also searched published literature and documents proposed by professional organizations for recommendations regarding T-lymphocyte testing and reporting. This article compares guidelines for reporting TLI results, as proposed by the National Committee for Clinical Laboratory Standards in Document H42-P, with samples of reports obtained in our case series. Most reports follow some, but not all, of the proposed guidelines. A majority of the laboratories provided interpretations of the results in their reports. We found considerable variation in normal reference ranges. We describe this variation in detail for the CD4+ T-lymphocyte counts and CD4+ T-lymphocyte percentages. This article describes some of the TLI result report forms currently being used and identifies important quality issues in this rapidly expanding area of clinical laboratory testing.

Forms and Records Control↗
PubMed1992

Human T-lymphotropic virus type I/II. Status of enzyme immunoassay and western blot testing in the United States in 1989 and 1990.

In three performance evaluation surveys, panels that consisted of human T-lymphotropic virus type I or type II (HTLV-I/II) antibody-positive and -negative plasma samples were mailed to laboratories that voluntarily participated in the Centers for Disease Control Model Performance Evaluation Program. Donor samples were identical among surveys. In each survey, more than 98% of the laboratories reported enzyme immunoassay (EIA) test results; about 11% also reported results of Western blot (WB) testing. Variation in analytic sensitivity (96.7% to 99.4%) and specificity (98.3% to 99.5%) of EIA tests was noted in the three surveys. For WB testing, no nonreactive interpretations were reported for HTLV-I/II antibody-positive samples in any survey; however, indeterminate interpretations were reported for 35.2% to 40.7% of the WB tests that were performed on HTLV-I/II antibody-positive samples. More than 95% of these indeterminate WB test interpretations were reported for HTLV-II antibody-positive samples. Although HTLV-I/II antibody tests are generally sensitive and specific, their accuracy could be further improved by increasing the specificity of EIA tests and the sensitivity of WB tests.

Blotting, Western↗
PubMed1992

Analytic sensitivity and specificity of enzyme immunoassay results in testing for human immunodeficiency virus type 1 antibody.

In 1986, a performance evaluation program at the Centers for Disease Control was implemented to assess the quality of performance of laboratories testing for human immunodeficiency virus type 1 antibody and to identify problems that occur during the testing process. Laboratories participating in the Centers for Disease Control Model Performance Evaluation Program for human immunodeficiency virus type 1 antibody testing furnished enzyme immunoassay results after they tested performance evaluation panels that were sent to them in August and November 1989. The panels consisted of 10 individual samples containing antibody-negative and antibody-positive samples, some of which were duplicates. Not all laboratories received the same panel of samples. Low false-negative and false-positive rates, as well as high intrashipment and intershipment reproducibility, indicate that most laboratories did not experience difficulty in testing performance evaluation samples sent to them in August and November 1989.

Evaluation Studies as Topic↗
PubMed1991

Binding of S protein by Neisseria gonorrhoeae and potential role in invasion.

An agglutination assay was used to examine the binding of purified human S protein (vitronectin, serum spreading factor) to 201 clinical isolates of Neisseria gonorrhoeae. Strains belonging to the protein IA serovars were significantly (P less than 0.001) more reactive in agglutination tests with human S protein and were more serum resistant than strains belonging to the protein IB serovars. The strains from patients with disseminated infections belonged predominantly to the IA serovar (19 of 23) and, with the exception of IA-4 and certain IB serovars, avidly agglutinated with S protein. The serovar IA-4 and IB strains isolated from joint or cerebrospinal fluid failed to agglutinate with S protein and appeared to be less serum resistant than most other IA isolates. Cysteine hydrochloride or 2-mercaptoethanol inhibited agglutination of S protein and a more than twofold increase in resistance to killing by fresh human serum following preincubation with S protein; the serum-sensitive parent strain did not agglutinate S protein, and serum resistance was not increased following preincubation with this protein. Binding of S protein by gonococci may represent a novel pathogenic mechanism that can contribute to serum resistance.

Agglutination↗
PubMed1990

Indirect immunofluorescence test performance and questionnaire results from the Centers for Disease Control Model Performance Evaluation Program for human immunodeficiency virus type 1 testing.

Results from laboratories performing indirect immunofluorescence (IIF) testing for human immunodeficiency virus type 1 antibody and participating in the Centers for Disease Control Model Performance Evaluation Program in 1988 are presented. Approximately 90% of all laboratories receiving specimen panels or questionnaires furnished results to the Centers for Disease Control. In September 1988, 111 reports were received from IIF laboratories from 34 states and nine countries; most of these laboratories did IIF testing in conjunction with other antibody tests. Hospital laboratories were the most common type of laboratory participating in the program. Laboratories that performed IIF employed fewer personnel and performed testing less frequently than did laboratories that performed enzyme immunoassays or Western blot (immunoblot) tests and were likely to use a commercial test kit. Most of the laboratories that referred specimens for IIF testing sent them to the state laboratory. The analytic specificity for the Model Performance Evaluation Program specimens was 98.5% when indeterminate results on a negative specimen were considered correct (negative) and 89.6% when indeterminate results on a negative specimen were considered incorrect; analytic sensitivity was 94.8% when indeterminate results on a positive specimen were correct (positive) and 91.4% when indeterminate results on a positive specimen were considered incorrect. When indeterminate results were considered correct, all types of laboratories (blood bank, state, hospital, independent, and other) had analytic specificities over 96%, and all manufacturers had analytic specificities above 95%. All types of laboratories had analytic sensitivities over 92%, and analytic sensitivities were above 94% for all manufacturers and reagent sources except Cellular Products. Comparison of percentages of correct responses between IIF and Western blot assays on those samples for which there was good agreement on the target interpretation revealed no significant differences. Both individual donor and diluted materials were included in the evaluations; the diluted donor material presented the greatest testing difficulty. Within-survey reproducibility was about 93% overall and by specimen type. Between-survey reproducibility was about 81% for negative and indeterminate specimens and 88.5% for positive specimens, for an overall between-survey reproducibility of 84.3%. Differences in performance were noted when results were compared by type of laboratory and test manufacturer.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Centers for Disease Control perspective on quality assurance for human immunodeficiency virus type 1 antibody testing. Model Performance Evaluation Program.

Ensuring high quality in human immunodeficiency virus type 1 (HIV-1) antibody testing is an essential component of the organized public health response to epidemic HIV-1 infection. In 1986, the Centers for Disease Control designed the Model Performance Evaluation Program to assess and improve the analytic quality of HIV-1 antibody testing. In addition, the program was designed to gather information about HIV-1 antibody testing practices. The utility of this information is in identifying potential barriers to quality throughout the total testing process. Currently, 1405 laboratories participate in the program. Participating laboratories are located both within and outside the United States and consist primarily of hospitals, blood banks, health departments, and independent laboratories. The responses to a questionnaire completed by 1050 program-participant laboratories in September 1988 suggest that at several stages in the HIV-1 antibody total testing process, laboratory practices (including the interpretation of Western blot patterns) are variable and that standardization of these practices would improve quality.

Centers for Disease Control and Prevention, U.S.↗
PubMed1989

Comparison of isolates of Neisseria gonorrhoeae causing meningitis and report of gonococcal meningitis in a patient with C8 deficiency.

We studied a previously healthy 20-year-old woman who presented with gonococcal meningitis. The gonococcal isolate, HT-1, was prototrophic by auxotyping, was protein I serovar IB-1, and agglutinated with wheat germ lectin. This isolate differed from the proline-requiring, serovar IA-1 and IB-4, wheat germ-agglutination-negative gonococcal isolates recovered from three patients during a recent outbreak of gonococcal meningitis in Philadelphia. HT-1 was killed by normal pooled human sera (greater than or equal to 98% at 30 min) but not effectively killed by the convalescent-phase sera of the patient (greater than 30% survival at 30 min). Similar results were obtained when mucosal and cerebrospinal fluid isolates from a Philadelphia patient were exposed to these sera, but mucosal and blood isolates from another Philadelphia case showed increased resistance to killing by normal pooled human sera. Further characterization revealed multiple differences in outer membrane and cellular proteins and lipopolysaccharide between case isolates. Absence of the L8 lipopolysaccharide epitope was noted for all isolates. Sera of our patient were found to have low total hemolytic complement (CH100 = 21 U/ml; normal = 55 to 100 U/ml) due to deficiency of C8 (C8 less than 1,000 CH50 U/ml; normal = greater than or equal to 16,000 CH50 U/ml). This is the first reported case of gonococcal meningitis occurring in a patient with a terminal-complement deficiency. Gonococcal meningitis is a rare complication of gonococcal bacteremia. Both defects in host defenses (e.g., terminal-complement deficiency) and organisms with unusual virulence appear to contribute to the pathogenesis of this complication of gonococcal bacteremia.

Adult↗
PubMed1988

Randomized comparative study of 0.5 and 1 g of cefodizime (HR 221) versus 1 g of cefotaxime for acute uncomplicated urogenital gonorrhea.

Uncomplicated urogenital and concomitant oropharyngeal gonorrhea in 424 male and female patients was treated in a randomized comparative study with 0.5 g of cefodizime (89 men and 54 women), 1 g of cefodizime (87 men and 52 women), or 1 g of cefotaxime (86 men and 56 women). The cure rates were 100% for men and women in the group given 0.5 g of cefodizime, 100% for men and women in the group given 1 g of cefodizime, and 99% for men and 100% for women in the group given 1 g of cefotaxime. The MICs of cefodizime and cefotaxime for the isolate of Neisseria gonorrhoeae ranged from 0.004 to 0.06 micrograms/ml. Chlamydia trachomatis was isolated before treatment in 15% and after treatment in 13% of all patients. Side effects, such as nausea, diarrhea, abdominal pain, genital candidiasis, and pain at the site of injection, developed in 4% of the patients given cefodizime. Side effects, such as vertigo, genital candidiasis, fatigability, and diarrhea, developed in 4% of the patients treated with cefotaxime. In both groups of patients, the side effects were mild and transient. Cefodizime and cefotaxime are safe and effective agents in the treatment of uncomplicated urogenital gonorrhea.

Cefotaxime↗
PubMed1987

Comparative double-blind study of 200- and 400-mg enoxacin given orally in the treatment of acute uncomplicated urethral gonorrhea in males.

In a double-blind randomized study, 155 male patients with uncomplicated urethral gonorrhea were given 200 mg (one capsule with 200 mg and one capsule with placebo; n = 77) or 400 mg (two capsules with 200 mg; n = 78) of enoxacin orally. The cure rates in the 200- and 400-mg treatment groups were 90 and 92%, respectively. The enoxacin MIC for the isolated Neisseria gonorrhoeae strains ranged from 0.015 to 0.12 microgram/ml. Postgonococcal urethritis was diagnosed in 29 (42%) patients in the 200-mg treatment group and 19 (26%) patients in the 400-mg treatment group. Side effects (nausea, headache, and vomiting) occurred in 2 (3%) of the 77 patients in the 200-mg treatment group and in 3 (4%) of the 78 patients in the 400-mg treatment group.

Acute Disease↗
PubMed1987

Western blot analysis of the human serum response to Mycoplasma hominis.

Mycoplasma hominis is a human genital pathogen with importance in postpartum pregnancy complications (postpartum fever/endometritis). Previous research has suggested that serum antibody levels to M. hominis are important in predicting which groups of women are at risk. M. hominis strain PG21 was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots to determine which protein antigens would be good candidates for use in serologic tests. Western blots of strain PG21 were probed with acute and convalescent human sera from patients with culture-confirmed M. hominis infections, animal sera directed against strain PG21 and other M. hominis strains, and sera from patients with confirmed infections from other sexually transmitted diseases (STD). Western blot analysis showed that the prenatal (Groups I, II, III) and convalescent (Group IV) M. hominis human sera reacted with proteins with apparent MWs of 106, 67, 46, and 40 kilodaltons (kDa). Only the convalescent sera (Group IV) and the prenatal sera (Group III) reacted with proteins having apparent MWs of 58 and 50 kDa. Animal antisera directed against all strains of M. hominis examined showed that these proteins were reactive in all strains, and other STD human sera did not react with proteins in strain PG21 corresponding to the apparent MWs of 50 and 58 kDa. Preliminary evidence suggested that proteins with the apparent MWs of 50 and 58 kDa may be viable candidates for use in serologic tests for the detection of human anti-M. hominis antibodies and help to eliminate cross-reactivity observed with whole-cell lysates.

Adult↗
PubMed1986

Use of dot-immunobinding and immunofluorescence assays to investigate clinically suspected cases of chancroid.

In 1984 and 1985, outbreaks of genital ulcers occurred in Florida and New York. Initial investigations for syphilis, herpes simplex, Chlamydia trachomatis, and Haemophilus ducreyi did not implicate any of these organisms as etiologic agents. From the results of dot-immunobinding assays, we found that sera from the patients had higher levels of IgM (30 [47.6%] of 63 patients) and IgG (22 [34.9%] of 63 patients) reactivities with an outer-membrane preparation from H. ducreyi strain CIP542 than with outer-membrane preparations from Haemophilus influenzae ATCC 10211 or Haemophilus parainfluenzae ATCC 7901. In contrast, sera from 35 patients in the control group did not react with any of the outer-membrane preparations (P less than .01 for both IgM and and IgG reactivity), nor did sera from eight individuals with disease caused by H. influenzae (P = .051 for IgM reactivity, P = .02 for IgG reactivity). Indirect immunofluorescence assay using a monoclonal antibody reactive with outer-membrane preparations from H. ducreyi strain CIP542 stained organisms in smears of lesion material from genital ulcers from three of six patients. These results suggested that the cause of both outbreaks of genital ulcers was H. ducreyi which was subsequently isolated in both geographic areas.

Antibodies, Bacterial↗
PubMed1985

Epidemiological characterization of Neisseria gonorrhoeae by lectins.

A total of 101 isolates of penicillinase-producing and non-penicillinase-producing Neisseria gonorrhoeae with known nutritional requirements, plasmid content, and serovars, were examined for lectin agglutination patterns. These isolates were from outbreaks in Georgia, California, Hawaii, and Pennsylvania. Cell suspensions made from 16- to 18-h cultures were mixed with 14 different lectins, and the resultant agglutination patterns were classified as agglutination groups. Among the 101 isolates tested, 24 different agglutination groups were demonstrated. Of the organisms tested, 55% were located in 3 of the 24 groups, and 86% of the isolates reacted with the lectins Trichosanthes kinlowii, Griffonia simplicifolia I, peanut agglutinin, soybean agglutinin, potato agglutinin, and wheat germ agglutinin. One isolate did not react with peanut or potato agglutinin, five isolates lacked reactivity with potato agglutinin, and six isolates did not react with wheat germ agglutinin. Of the wheat germ-negative isolates, four were from Pennsylvania and were identical with regard to auxotype, plasmid content, serovar, and lectin group. The other two wheat germ-negative isolates were from California and were unrelated by the same criteria to the four Pennsylvania isolates and to each other. Among the isolates tested, there were no differences in lectin groups with regard to the sex of the patient. In the Georgia collection, agglutination with one lectin group was confined to isolates of serogroup IA. This association was not observed for the other geographic areas. Some isolates showing identical auxotype, plasmid content, and serovars could be differentiated based on lectin agglutination patterns, whereas other isolates were identical by all testing criteria.

Agglutination Tests↗