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The long-term within- and between-laboratory variability for assay of antithrombin, and proteins C and S: results derived from the external quality assessment program for thrombophilia screening of the ECAT Foundation.

A stable laboratory performance is important for comparability and transferability of laboratory data both within and between laboratories. The lack of a reference system within hemostasis hampers laboratories in establishing their laboratory performance over a prolonged period of time. Therefore, based on data from an external quality assessment program, we evaluated the between laboratory variation (CVBETWEEN) and the long-term within-laboratory variation (LCVa) for antithrombin, and proteins C and S. We evaluated the CVBETWEEN for the period 1996-2001, including the results of 64-240 laboratories from 23 different surveys (protein S activity 15 surveys). We observed a quite high CVBETWEEN and a broad range for each analyte. The CVBETWEEN was significantly higher for antithrombin and protein S for samples with low levels similar to heterozygous deficiencies. We also evaluated the LCVa, including the results of 136 laboratories. The lowest LCVa[median and 95% content interval (CI)] was observed for antithrombin (7.6%; 3.6-35.5%), intermediate values for protein C activity and antigen (8.6%; 3.5-25.3% and 10.8%; 4.8-33.1%, respectively) and highest values for the protein S variables (13.4%; 6.4-50.6% for total protein S antigen, 14.1%; 6.5-79.1% for free protein S antigen and 17.2%; 7.2-84.3% for protein S activity). We concluded that the main reason for the high CVBETWEEN is the long-term within-laboratory variability. Application of linear regression on data of an external quality assessment program is a useful model to demonstrate per analyte per laboratory the long-term variability (LCVa). It is concluded that improvement of the long-term within-laboratory test performance is the first priority in hemostasis to yield important improvements in the comparability and transferability of laboratory data.

Antithrombin III↗

Clinical hematology practices at veterinary teaching hospitals and private diagnostic laboratories.

The clinical hematology practices utilized at veterinary teaching hospitals and private veterinary diagnostic laboratories were surveyed using a questionnaire. The hematology caseload at private diagnostic laboratories was larger, and comprised predominantly of canine and feline submissions. The Coulter S Plus IV and Serono Baker 9000 were the hematology analyzers used most frequently at veterinary medical laboratories. The Abbott Cell-Dyn 3500, a multispecies analyzer capable of leukocyte differential counting, was utilized more by private laboratories. Commercial hematology control reagents were used at all laboratories; teaching hospital laboratories more often used reagents supplied by the manufacturer of the analyzer. A greater percentage of private diagnostic laboratories participated in the external quality assurance programs offered by Veterinary Laboratory Association and College of American Pathologists. While private diagnostic laboratories retained the EDTA blood specimens longer after initial testing, the teaching hospital laboratories retained blood smears and complete blood count reports longer. The complete blood count reports at veterinary teaching laboratories more often included red blood cell volume distribution width, mean platelet volume, manual hematocrit, plasma protein, and leukocyte differentials as absolute concentrations. The laboratory practices utilized by these veterinary medical laboratories were generally similar, and differences were attributed to divergent emphasis on economic accountability and clinical investigation.

Journal Article↗

Reproducibility of risk figures in 2nd-trimester maternal serum screening for down syndrome: comparison of 2 laboratories.

BACKGROUND: Analytical error affects 2nd-trimester maternal serum screening for Down syndrome risk estimation. We analyzed the between-laboratory reproducibility of risk estimates from 2 laboratories. METHODS: Laboratory 1 used Bayer ACS180 immunoassays for alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), Diagnostic Systems Laboratories (DSL) RIA for unconjugated estriol (uE3), and DSL enzyme immunoassay for inhibin-A (INH-A). Laboratory 2 used Beckman immunoassays for AFP, hCG, and uE3, and DSL enzyme immunoassay for INH-A. Analyte medians were separately established for each laboratory. We used the same computational algorithm for all risk calculations, and we used Monte Carlo methods for computer modeling. RESULTS: For 462 samples tested, risk figures from the 2 laboratories differed >2-fold for 44.7%, >5-fold for 7.1%, and >10-fold for 1.7%. Between-laboratory differences in analytes were greatest for uE3 and INH-A. The screen-positive rates were 9.3% for laboratory 1 and 11.5% for laboratory 2, with a significant difference in the patients identified as screen-positive vs screen-negative (McNemar test, P<0.001). Computer modeling confirmed the large between-laboratory risk differences. CONCLUSION: Differences in performance of assays and laboratory procedures can have a large effect on patient-specific risks. Screening laboratories should minimize test imprecision and ensure that each assay performs in a manner similar to that assumed in the risk computational algorithm.

Adult↗

Laboratory containment of SARS virus.

Following the severe acute respiratory syndrome (SARS) outbreak in 2003, a large number of clinical and environmental samples containing/potentially containing SARS coronavirus (SARSCoV) as well as SARS-CoV stocks were retained in clinical and research laboratories. The importance of laboratory biosafety was demonstrated by the occurrence of laboratory incidents in Singapore, Taiwan and Beijing. It is imperative that safe practice and techniques, safety equipment and appropriate facility design should be in place to reduce or eliminate exposure of laboratory workers, other persons and the outside environment to SARS-CoV containing materials. Discussion on laboratory containment of SARS-CoV was initiated in Hong Kong in August 2003. It was agreed that an inventory of all specimens with the potential presence of SARS-CoV collected for any diagnostic or research purposes from November 2002 to July 2003 should be established in each laboratory. They should be stored in a secure place at the appropriate biosafety level with access control. Un-needed samples collected during the period should be destroyed. These laboratories should be audited to ensure inventories are updated. The audit should include safety and security measures to detect irregularities. Any laboratory accidents involving materials suspected of containing SARS-CoV should be reported to the authorities and all personnel exposed closely followed medically. A contingency plan should be in place in the laboratory and a drill conducted regularly to test its efficacy. By January 2004, all clinical laboratories performing SARS-CoV testing in Hong Kong set up inventories to document location and types of SARS-CoV containing materials retained in their laboratory. Audits of these laboratories in 2004 showed that laboratory safety and containment requirements as recommended were generally met.

Disease Outbreaks↗

Initiatives toward effective decision making and laboratory use.

Escalating health care costs constitute a public issue of paramount importance today, Among the leading growth factors in this rise is the cost of hospital services, notably laboratory services. With respect to the clinical laboratory, rising costs appear to be almost entirely attributable to expanding utilization and introduction of new services. The clinical laboratory has gone through a technological revolution in two decades that has changed it from a largely manual to a highly automated system of great speed and capacity. This change had produced a change in the style of providing services, a change that includes the provision of quantities of unsolicited data. A parallel change in the style of use of the laboratory has taken place on the part of patient care physicians from a relatively sparing, problem oriented use pattern to a relatively lavish, data oriented one. These reciprocal changes have transformed medicine, in the United States, at least, into a relatively high laboratory use culture. Abandonment of the new technology and return to a simpler, more primitive laboratory world would be a drastic and most inappropriate response to the new situation. Furthermore, arbitrary measures such as rationing, quotas, and tariffs are, if enacted, almost certain to fail. The most effective long term strategies, though more demanding of time and effort, lie through modification of physician behavior through the pathways of education and research. Education and research initiatives now in progress can in time influence laboratory use patterns of physicians at all career levels, improving the logic of test use and providing more strategic, prudent, and cost effective overall laboratory utilization practices. These approaches will require much improved communication between laboratory and bedside and a new intense involvement of laboratory physicians and scientists in the tasks of helping to improve the use of laboratory tests and laboratory data.

Attitude of Health Personnel↗

Disinfection and communication practices: a survey of U.S. dental laboratories.

BACKGROUND: The need to disinfect impressions is crucial to prevent the transmission of infectious diseases. The authors report the results of a survey of U.S. dental laboratory directors. The survey was designed to determine how well dental laboratory personnel are communicating with dentists regarding the disinfection of impressions, and, in turn, what laboratory technicians are doing to protect themselves against microbial cross-contamination. METHODS: Four hundred dental laboratory directors were selected in a blinded and random manner. To create a geographically representative sample, an equal number of laboratory directors from the East, Midwest and West were interviewed. A survey consisting of 16 open-ended questions was conducted by trained interviewers via 10- to 15-minute telephone interviews. All dental laboratory directors stated that they were thoroughly familiar with their laboratory's disinfection protocol. RESULTS: The survey documented that the majority of impressions were made of polyvinyl (57 percent) or polyether (27 percent) materials. Only 44 percent of the respondents stated that they knew if the impressions they received had been disinfected. Twenty-three percent of the laboratory directors did not know the method of disinfection used, and 47 percent did not know the length of time involved. Forty-five percent of the respondents reported that they receive inadequate instruction in regard to disinfection techniques. No one class of impression materials was found to be more problematic than others by the laboratory directors. CONCLUSIONS: The results indicate a significant and problematic lack of communication between these team members. The responses also suggested that laboratory-perceived problems with impressions were not linked to any particular type of material, but more to the disinfection technique used. PRACTICE IMPLICATIONS: Lack of communication between dentists, staff members and dental laboratory personnel, along with poor training of laboratory personnel in disinfection techniques, may have a direct effect on the prosthetic results achieved in dental practices.

Administrative Personnel↗

The planning, operation, and function of a clinical laboratory in a teaching hospital.

Shortly after World War I, laboratories began to grow in number and complexity in the hospitals throughout the United States. Need dictated the funding and therefore, expansion of these laboratories. In general, very little overall planning was introduced into the development of these laboratories but rather empiricism and reaction to pressure dictated the day-to-day, week-by-week development. Since a great deal of the teaching at that time was done on a one-by-one basis with laboratory learners, and since much of the laboratory work was done by physicians and used directly upon the patient, there was very little need for considering the laboratory as a more global resource for the teaching institution. As the science of medicine advanced and as the diversity and complexity of laboratory occupations increased, it was necessary to place more stress upon careful planning and operation of the clinical laboratory in the teaching institution. The laboratory was approached not only as a training area in its own right but as an adjunct to the undergraduate and postgraduate medical education occurring in the teaching institution. It became paramount then to consider the detail planning necessary to bring about a structural and functional entity that could respond to these more global teaching needs. It was imperative that the laboratory itself respond to its role and responsibility in the tripartite function of a teaching institution -- research, education, and service. In any good planning environment, effort must be expended towards setting goals and objectives; analytical methods applied to making assumptions and establishing premises. Alternate means for achieving goals and objectives were developed. Energy was expended in making forecasts and projecting results. Alternate means were sorted out and choices were made. Implementation guidelines were designed and an evaluation and feedback mechanism was instituted. In more recent years, we have attempted to apply these steps in planning to the development of laboratories and to the installation of operational procedures which would allow the clinical laboratory to truly function as a teaching unit and as a vital resource for the total training program of the institution in which it is housed.

Clinical Laboratory Techniques↗

Clinical laboratory radioimmunoassay usage.

OBJECTIVES: To determine the extent of radioimmunoassay utilization in clinical laboratories in the state of Texas; to ascertain what methods have replaced it as an analytical tool; to identify trends and elicit comments regarding attitudes toward radioimmunoassay; and to ascertain the extent of instruction of radioimmunoassay principles required in clinical laboratory science curricula. DESIGN: Mailed, written survey designed by the authors. PARTICIPANTS: Laboratory managers or directors of 203 clinical pathology laboratories in Texas. MAIN OUTCOME MEASURE: Responses to seven forced-choice items, prompting information regarding laboratory type and size, extent of radioimmunoassay use, benefits or radioimmunoassay, and replacement technologies; a single item that elicited responses and opinions regarding general attitudes about radioimmunoassay and its place in clinical laboratory science curriculum. DATA SOURCE: Clinical laboratory managers or directors in the state of Texas. RESULTS: A total of 203 surveys were mailed within 127 respondents, yielding a response rate of 63%. The majority (77%) of clinical laboratories surveyed no longer use radioimmunoassay as a diagnostic tool with the predominant reason being the availability and affordability of automated enzyme immunoassays. Time-consuming recordkeeping was another common reason for abandoning the technique. Enzyme immunoassays were by far the most common method replacing radioimmunoassay. Comments reflected the general attitude that radioimmunoassay is a technique of the past in the clinical laboratory. A variety of views were elicited regarding the education of the principles of RIA to clinical laboratory science students. CONCLUSION: Radioimmunoassay, although a viable assay in some situations, has been abandoned as an analytical tool in most clinical laboratories in Texas. Current users are unhappy with the amount of paperwork that accompanies use of the technology, while non-users consider non-isotopic assays equivalent in sensitivity to RIA. In regard to information presented to clinical laboratory science students, the advent of molecular diagnostic techniques requires continued instruction in the principles of radioactivity, although not radioimmunoassay.

Clinical Laboratory Techniques↗

[A study on prevalence of resistance to antituberculosis drugs in Japan: comparison of results in the local facilities and in the reference laboratory].

During five years since the last survey of drug-resistant tuberculosis in Japan, features of tuberculosis in Japan have been changed. A nationwide survey was conducted by the Tuberculosis Research Committee of Japan. A total of 38 hospitals in various districts of Japan participated in the cooperative study. Each collaborating laboratory sent all mycobacterial cultures isolated during 1 June to 30 November, 1992 to the reference laboratory of the Committee, where species of the isolates were identified and drug susceptibility of Mycobacterium tuberculosis isolates were reexamined. The reference laboratory received a total of 1,236 cultures. Among them, 290 cultures were excluded from further examination by various reasons, such as contamination (52 cultures), non-viability (53), growth of nontuberculous mycobacteria (182) and other reasons (3). Thus, drug susceptibility test results were available for 946 cultures, including 26 cultures from non-Japanese persons. In the local laboratories, two methods, the absolute concentration method using 1% Ogawa egg slant (standard method, 26 hospitals) and its modified method using a microwell plate (microtiter method, 12 hospitals), were used for drug susceptibility testing, and the standard method was used in the reference laboratory. The results in the local laboratories were compared with those in the reference laboratory. The overall coincidence rate between drug susceptibility results reported from the local laboratories and those from the reference laboratory was 92.5%. A high coincidence rate (94.3%) was seen when the standard method was used in both local and reference laboratories. On the other hand, the coincidence rates between the results with the microtiter method in the local laboratory and those with the standard method in the reference laboratory were lower (standard method vs microtiter method; P < 0.01). Out of 19 hospitals, when the isolates were tested by the standard method 17 (89.5%) showed high coincidence rates (over 85%). Three hospitals using the microtiter method showed the coincidence rate over 90%, while other three showed lower rate (less than 80%) with high overestimation rates (over 19%), indicating that there are variations among facilities in performing the microtiter test. A part of the results concerning the resistance patterns to five antituberculosis drugs will be reported elsewhere.

Adolescent↗

[External quality assessment for clinical microbiology and good laboratory management].

The Tokyo Metropolitan external quality assessment (EQA) program has revealed some serious problems in private independent microbiology laboratories in Tokyo since 1982. The poor performance in the EQA surveys closely related to poor laboratory managements, the type of training, experience of the medical technologists or technicians, and supervisory ability of the consultant physicians in independent laboratories. Social factors impede the reform of the quality assurance of clinical microbiology. Such factors include poor infrastructure of continuing education for small private laboratories, closure of the central clinical laboratories in the hospitals and outsourcing of laboratory tests due to restructuring in response to economic problems, and limited numbers of certified clinical pathologists of the Japan Society of Clinical Pathology (JSCP). Therefore, the Tokyo Metropolitan EQA Scheme is still confidential and its main role is educational. Good two way communication between participants and the organizers' clinical pathologists is essential, if the quality of laboratory tests is to be improved. The new JSCP edition of the postgraduate training requirement in clinical pathology includes "Laboratory Administration and Management". Good laboratory management(GLM) is an increasingly important component of good laboratory practice. The practice activities of clinical pathologists must include general management in addition to exercising there specialized knowledge in medicine and technology. Whereas leadership of a good clinical pathologist provides the direction of where a good laboratory is going, good management provides the steps of how to get there. And I believe quality system models from business and industry may provide us with strong guidance to build a quality system for the good laboratory that will endure into the next century.

Education, Medical, Undergraduate↗

Assessment of commercial laboratories performing hair mineral analysis.

CONTEXT: Hair mineral analysis is being used by health care practitioners and promoted by laboratories as a clinical assessment tool and to identify toxic exposures, despite a 1985 study that found poor reliability for this test. OBJECTIVE: To assess whether the reliability of data from commercial laboratories advertising multimineral hair analyses for nutritional or toxicity assessment has improved since the 1985 study. DESIGN, SETTING, AND PARTICIPANTS: A split hair sample taken from near the scalp of a single healthy volunteer was submitted for analysis to 6 commercial US laboratories, which analyze 90% of samples submitted for mineral analysis in the United States. MAIN OUTCOME MEASURES: Agreement of test results for each analyte, laboratory reference ranges, laboratory characteristics, and interpretation of health implications. RESULTS: Laboratory differences in highest and lowest reported mineral concentrations for the split sample exceeded 10-fold for 12 minerals, and statistically significant (P<.05) extreme values were reported for 14 of the 31 minerals that were analyzed by 3 or more laboratories. Variations also were found in laboratory sample preparation methods and calibration standards. Laboratory designations of normal reference ranges varied greatly, resulting in conflicting classifications (high, normal, or low) of nearly all analyzed minerals. Laboratories also provided conflicting dietary and nutritional supplement recommendations based on their results. CONCLUSIONS: Hair mineral analysis from these laboratories was unreliable, and we recommend that health care practitioners refrain from using such analyses to assess individual nutritional status or suspected environmental exposures. Problems with the regulation and certification of these laboratories also should be addressed.

Biomarkers↗

The laboratory is a key partner in assuring patient safety.

Medical errors have a great impact on patient outcomes. They can cause serious injury to patients or even result in their deaths. However, morbidity and mortality can sometimes be prevented by the timely and effective action of health care workers. Several IOM Reports have focused on the problem of errors in the United States health care system and identified gaps that need to be addressed. As part of the overall health care system, clinical laboratories are vulnerable to medical errors. Because of significant efforts on the part of both the laboratories and the manufacturers of laboratory equipment and reagents, the errors in the analytic phase of the total testing process now represent the smallest portion of testing errors. Currently, laboratory testing errors occur most frequently in the preanalytic phase. The primary reason for the high prevalence of preanalytic errors is that, at the present time, it is difficult to monitor all preanalytic variables and to implement necessary improvement processes, particularly when some of the variables (like phlebotomy) are not under the control of the laboratory. Considerable efforts have been made by laboratory professionals and other stakeholders to decrease testing errors. Minimal quality requirements have been set through regulations for both laboratory testing and the manufacture of medical equipment and reagents. At the same time, nonregulatory approaches have greatly affected the quality of laboratory testing. These include laboratory standards, various quality improvement programs, voluntary reporting of adverse events, and, in the near future, the National Report on the Quality of Laboratory Services. The introduction of successful approaches from other industries, such as Six Sigma and Lean, also will help reduce the rate of laboratory errors. The clinical laboratory has done more than most other sectors of health care to decrease the occurrence of medical errors, making it a key partner inpatient safety.

Humans↗

Interpretative comments and reference ranges in EQA programs as a tool for improving laboratory appropriateness and effectiveness.

INTRODUCTION: Laboratory information is generated when a meaning is given to certain data. This is usually achieved by comparing a laboratory test result with the reference range/decisional limit (RL), and by providing consultation for the interpretation of data, advice, and follow-up testing. AIM: In this paper, we investigate factors affecting the conversion of data into useful information with regard to biochemical markers of myocardial damage (CK-MB mass, myoglobin, and troponins), in view of their importance in detecting myocardial necrosis. Our aim was to report results obtained in order to verify the consensus between laboratories with reference to interpretative comments and the reference ranges/decisional limits added to clinical reports. METHODS: A questionnaire and simulated medical reports on three different patients were distributed to participants (94 laboratories) in the 2001 cycle of the External Quality Assessment (EQA). Moreover, we analysed 113 medical reports sent by laboratories during the most recent EQA cycle 2002, and checked the number of different RLs used, both independent and within the diagnostic system used. We also compared each laboratory result of a control sample, obtained in the 2002 cycle, with declared RL in order to verify the clinical significance of results ("normal" or "pathological") for troponin I and CK-MB. RESULTS: Our findings show that few laboratories regularly add interpretative comments to medical reports. On the contrary, they cooperate with clinicians who require consultation, advice, and information for the appropriate use of biochemical markers. There is a general consensus among participants regarding probable syndromes suggested by the interpretation of the same result and most laboratories also agree on further investigations to be carried out for several diseases. Concerning RL, the data demonstrate that numerous different RLs are used to report the results of the biochemical markers evaluated, both when considered independent of the diagnostic system used and within the diagnostic system used. DISCUSSION AND CONCLUSIONS: The biochemist does not have the opportunity to verify the efficacy of the interpretation that he/she provided. An audit of this activity is therefore required to allow the laboratory to monitor its own performance and to assure good practice. The evaluation of interpretative comments, through specific surveys, should be a prime objective of EQA organisers. Well-designed EQA programs can, moreover, support laboratories in establishing appropriate RL and in verifying the clinical significance of their results with respect to that of other laboratories. Our survey on interpretative comments and the analysis of the RLs further demonstrate how laboratory medicine can contribute to the objective evaluation of the patients' health status.

Clinical Laboratory Techniques↗

An international survey of current practice in the laboratory assessment of anticoagulant therapy with heparin.

AIMS: We conducted a survey of laboratory practice for assessment of heparin anticoagulant therapy by participants of the Royal College of Pathologists of Australasia Quality Assurance Program (RCPA QAP). METHODS: A questionnaire was sent to 646 laboratories enrolled in the Haematology component of the QAP, requesting details of tests used for monitoring heparin therapy. RESULTS: Seventy laboratories (10.8%) returned results that indicated that they performed laboratory monitoring of heparin therapy. Most laboratories (69/70 = 98.6%) use the activated partial thromboplastin time (APTT) to monitor unfractionated heparin, with eight (11.4%) also using the APTT for monitoring low molecular weight (LMW) heparin. Five (7.1%) laboratories use the thrombin time (TT) test to help monitor heparin therapy and 37 (52.9%) laboratories use an anti-Xa assay to monitor heparin (either LMW or unfractionated). Normal reference ranges (NRR) for APTT differed considerably between laboratories, even those using the same reagent. Therapeutic ranges (TR) also differed considerably between laboratories, for both APTT and the anti-Xa assay. Laboratory differences in NRR and TR using the same reagents could only be partly explained by the use of different instrumentation. CONCLUSIONS: There is a large variation in current laboratory practice relating to monitoring of heparin anticoagulant therapy. This finding is similar to that of a similar survey conducted by the RCPA QAP almost a decade ago. This study suggests that better standardisation is still required for laboratory monitoring of heparin therapy.

Anticoagulants↗

Laboratory proficiency test results on use of selective media for isolating Pseudomonas cepacia from simulated sputum specimens of patients with cystic fibrosis.

Pseudomonas cepacia colonization of or infection in patients with cystic fibrosis (CF) has been associated with increased morbidity and premature death. However, current data on national incidence may be biased because of interlaboratory differences in the methods of culturing sputa of patients with CF. We conducted three tests to evaluate the proficiency of microbiology laboratories at CF centers in identifying and isolating P. cepacia and to assess the value of using selective media for P. cepacia (P. cepacia agar and oxidation-fermentation polymyxin-bacitracin-lactose medium [OFPBL]) to recover P. cepacia from specimens simulating sputa of patients with CF. In test 1, we evaluated the proficiency of laboratories in identifying P. cepacia. Of 111 laboratories tested, 105 (95%) correctly identified P. cepacia. In test 2, we evaluated the proficiency of laboratories in isolating P. cepacia from simulated CF sputum specimens. Only 36 (32%) of 115 laboratories detected P. cepacia. Recovery of the microorganism was associated with the use of P cepacia agar or OFPBL; 14 (95%) of 15 laboratories using P. cepacia agar or OFPBL (or both) versus 22 (22%) of 100 laboratories not using either medium recovered P. cepacia (P less than 0.0001, Fisher exact test, one tailed). Laboratories failing test 2 were requested to use a selective medium for P. cepacia in a repeat test; 73 (97%) of 75 laboratories using P. cepacia agar or OFPBL (or both) versus 0 of 4 laboratories not using either medium detected P. cepacia (P less than 0.0001, Fisher exact test, one tailed). Our studies show that (i) microbiology laboratories at CF centers are proficient in identifying P. cepacia, and (ii) the use of selective media for P. cepacia enhances recovery of the microorganism in simulated sputum specimens. Therefore, we recommend the use of selective media for P. cepacia in laboratories processing sputa of patients with CF.

Culture Media↗

Current practices in mycobacteriology: results of a survey of state public health laboratories.

Fifty-six state and territorial public health laboratories were surveyed to determine whether currently available rapid methods for the identification and drug susceptibility testing of Mycobacterium tuberculosis were being performed. Forty (71%) laboratories use fluorochrome rather than conventional basic fuchsin stains for screening clinical specimens for acid-fast bacilli. Of the 55 laboratories that routinely culture for mycobacteria, 16 (29%) use the more rapid radiometric methods. Species identification of isolates is done by biochemical tests in 13 (23%) laboratories; 40 (72%) use nucleic acid probes, high-performance liquid chromatography, or the BACTEC p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) test (rapid tests); 3 laboratories do not perform species identification. Drug susceptibility testing is performed with solid media by 36 of 45 (80%) laboratories, while the more rapid radiometric methods are used by 9 (20%) laboratories. Compared with the laboratories that use conventional methods, laboratories that use rapid methods report results more quickly: for species identification, 43 days (conventional) versus 22 days (rapid); for drug susceptibility testing, 44 days (conventional) versus 31 days (rapid) from specimen processing. Rapid technologies for microscopy and species identification are being used by many, but not all, state and territorial public health laboratories; however, most laboratories do not use the more rapid radiometric methods for routine culture or drug susceptibility testing of mycobacteria. Implementation of such rapid technologies can shorten turnaround times for the laboratory diagnosis of tuberculosis and recognition of drug resistance.

Bacteriological Techniques↗

Evaluation of laboratory testing methods for Chlamydia trachomatis infection in the era of nucleic acid amplification.

Diagnostic tests presently available for Chlamydia trachomatis have widely varying performance characteristics. To assess evolving laboratory testing practices since the introduction of nucleic acid amplification tests (NAAT), we surveyed laboratories in Washington State about their testing practices in 1998 and compared our findings to a similar survey conducted in 1995. Laboratory directors of 61 (87%) of 70 laboratories performing chlamydial tests in 1998 returned a survey. Between 1995 and 1998, 36 laboratories discontinued chlamydial testing, and the total number of laboratories performing tests in the state decreased from 92 to 70, a 24% decline. Of the 36 laboratories that discontinued testing, 25 (69%) had previously used rapid tests. While no laboratory routinely used NAAT in 1995, ligase chain reaction (LCR) was used in 23% of laboratories in 1998 and accounted for 113,624 (36%) of the 318,133 tests performed that year. Among the remaining 204,509 tests performed in 1998, other tests employed included DNA probe (29%), enzyme immunoassay (20%), culture (12%), direct fluorescent antibody assays (3%), and rapid tests (<1%). The majority (65%) of tests performed in 1998 using technologies other than LCR or culture were done in laboratories that did more than 10,000 tests. Cost and loss of revenue to laboratories were the most frequently cited reasons for not adopting NAAT. We conclude that in Washington State, NAAT have been rapidly adopted in larger laboratories, but most patients are still tested with much less sensitive technologies. Financial constraints represent the major barrier to more widespread use of DNA amplification tests.

Bacteriological Techniques↗

A national audit of the laboratory diagnosis of tuberculosis and other mycobacterial diseases within the United Kingdom.

In order to audit United Kingdom laboratory diagnostic and reference services including novel molecular methods for tuberculosis, a questionnaire was sent to laboratories submitting specimens to the PHLS Mycobacterium Reference Unit (MRU) and regional centres and to the Scottish Mycobacteria Reference Laboratory (SMRL) in 1996-7. Nationally, 67.2% of laboratories responded. Most UK laboratories were fully or conditionally CPA accredited and take part in the NEQAS proficiency scheme. On average only 3.3% of primary samples submitted for mycobacterial diagnosis in 1995 produced a mycobacterial culture from approximately half as many patients (that is, a mean of 1488 specimens producing 49 isolates from 23 patients). Potentially over 380,000 specimens are processed for mycobacteria in the UK each year. The majority of laboratories use 4% NaOH +/- NALC for specimen decontamination. Culture on solid media was used by most laboratories and 62.9% also use liquid media. Most laboratories incubated cultures for eight weeks. Few laboratories use molecular diagnostic methods. Laboratories were most likely to use molecular methods for diagnosing tuberculous meningitis and for specimens from immunocompromised patients, although usage was strongly influenced by cost. Within England and Wales 43.9% (47/107) and 56% (61/109) of laboratories wanted a rapid service for rifampicin resistance detection in M tuberculosis from immunocompetent and immunocompromised patients, respectively. In regard to a tuberculous meningitis service, 80.5% (43/112) and 84.3% (102/121) of laboratories wanted this service for immunocompetent and immunocompromised patients, respectively. The quality of reference services was rated as "very good"/"good" by 85.6% of respondents nationally. Rapid molecular amplification diagnostic services were established at the PHLS MRU for rifampicin drug resistance detection nationally and for tuberculous meningitis at the MRU.

Bacteriological Techniques↗