Search

Objectives: At the onset of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in the United States, testing was limited to the Centers for Disease Control and Prevention-developed reverse transcription polymerase chain reaction assay. The urgent and massive demand for testing prompted swift development of assays to detect SARS-CoV-2. The objective of this study was to assess the accuracy of these newly developed tests.Methods: The American Proficiency Institute sent 2 test samples to 346 clinical laboratories in order to assess the accuracy of SARS-CoV-2 assays. The positive sample, containing 5,175 viral copies/mL, was fully extractable with SARS-CoV-2 viral capsid protein and RNA. The negative sample, with 3,951 viral copies/mL, contained recombinant virus particles with sequences for targeting human RNAase P gene sequences.Results: Of the laboratories submitting results, 97.4% (302/310) correctly detected the virus when present and 98.3% (296/301) correctly indicated when the virus was not present. Among incorrect results reported in this proficiency challenge, 76.9% (10/13) were likely related to clerical error. This accounts for 1.6% (10/611) of all reported results.Conclusions: Overall performance in this SARS-CoV-2 RNA detection challenge was excellent, providing confidence in the results of these new molecular tests and assurance for the clinical and public health decisions based on these test results. [ABSTRACT FROM AUTHOR]

Background: This study assesses proficiency test (PT) performance in detecting and identifying malaria parasites and examines malaria screening practices in laboratories in the United States. Method: We reviewed PT data from 1999 to 2008 to determine the rates of unacceptable responses for detecting and identifying Plasmodium sp. We also surveyed current PT participants to assess malaria screening practices. Results: Laboratories were most proficient at detecting and identifying P falciparum and substantially less proficient at identifying P malariae, P vivax, and P ovale. Half of the surveyed laboratories failed to offer a complete diagnostic workup, 25.0% failed to screen both thick and thin slides, and 36.1% failed to issue a final report within 24 hours. Conclusion: Educational programs should focus on identifying Plasmodium sp. and distinguishing artifacts from parasites. Laboratories should offer a complete diagnostic workup, either in-house or by referral, and ensure final results within 24 hours. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess laboratories' ability to detect or rule out the presence of four common food pathogens: Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes and Campylobacter spp. To do this, qualitative proficiency test data provided by one proficiency test provider from 1999 to 2007 were examined. The annual and cumulative 9-year percentages of false-negative and false-positive responses were calculated. The cumulative 9-year false-negative rates were 7.8% for E. coli O157:H7, 5.9% for Salmonella spp., 7.2% for L. monocytogenes and 13.6% for Campylobacter spp. Atypical strains and low concentrations of bacteria were more likely to be missed, and the data showed no trend of improving performance over time. Percentages of false-positive results were below 5.0% for all four pathogens. PRACTICAL APPLICATIONS The results imply that food testing laboratories often fail to detect the presence of these four food pathogens in real food specimens. To improve pathogen detection, supervisors should ensure that testing personnel are adequately trained, that recommended procedures are followed correctly, that samples are properly prepared, that proper conditions (temperature, atmosphere and incubation time) are maintained for good bacterial growth and that recommended quality control procedures are followed. Supervisors should also always investigate reasons for unsatisfactory proficiency test results and take corrective action. Finally, more research is needed into testing practices and proficiency test performance in food testing laboratories. [ABSTRACT FROM AUTHOR]

Abstract: In June 2003, a test sample was sent to 355 laboratories enrolled in a proficiency testing program to assess their ability to detect low-level penicillin resistance in a strain of Streptococcus pneumoniae. One hundred fifty participants reported results for antimicrobial susceptibility testing. Of the 62 respondents using disk diffusion, 34 (55%) failed to report a result that was acceptable for detecting penicillin resistance and 30 (48%) reported a result for one or more drugs not approved for testing S. pneumoniae. Moreover, 12 (14%) of the 88 respondents using minimum inhibitory concentration methods reported results for at least one unapproved drug. These findings support the conclusions of other studies that antimicrobial susceptibility testing practices are suboptimal in many laboratories. Resolution of this problem will require continued educational initiatives, studies to discover the reasons why laboratories fail to follow published standards, and enforcement of the use of standards by regulatory and credentialing agencies. [Copyright &y& Elsevier]

Abstract: External laboratory proficiency programs are an important requirement for test quality assurance (EQA) and compliance to regulatory guidelines (Clinical Laboratory Improvement Amendments and inspections). The American Proficiency Institute (API) regularly distributes EQA sample challenges (test events) including an Educational Sample (ES) for antimicrobial susceptibility testing. Beginning in 2007, API has sent 3 ES samples annually, each a well-characterized (molecular/phenotypic methods) strain having an interesting/emerging mechanism of resistance. Hundreds of USA laboratories, usually serving small- to medium-size hospitals and clinics, participate in the API ungraded ES test event. Analysis of responses is made and reported electronically as ES critiques addressing contemporary susceptibility testing issues that affect patient therapy. Seven Gram-positive (+) and 8 Gram-negative (−) ES strains were tested over the 5 years (2007–2011) with organism identification (graded) accuracy of 95.3% (range, 91.0–99.2%) for Gram (−) and 97.0% (range, 94.2–100.0%) for Gram (+) challenges. Susceptibility testing categorical accuracy was generally greatest for the disk diffusion test (91.0/97.0%) compared to the MIC methods (commercial automated or manual) combined (89.9/96.1%, for Gram [−]/Gram [+], respectively). The most worrisome observations of these ES samples were as follows: 1) poor recognition of ESBL- and serine carbapenemase-producing strains (various types including Klebsiella pneumoniae carbapanemase) due to delayed application of Clinical and Laboratory Standards Institute [CLSI] guidelines; 2) overcalling of ESBL in organisms having wild-type non-ESBL enzymes (OXA series; OXA, 1/30) due to commercial system or participant interpretive error; and 3) occasional drug-bug discords noted in nonfermentative Gram (−) bacilli. In conclusion, the API ES series of ungraded susceptibility testing challenges (accuracy was >90%) has been well received by subscribers and has provided detailed educational opportunities to improve laboratory testing performance. ES samples have delivered guidance to enable laboratories to rapidly comply with CLSI document changes of interpretive breakpoints such as those for β-lactams when testing Enterobacteriaceae and Pseudomonas aeruginosa; the program was sustained into 2012 and beyond to document quality of susceptibility tests in USA laboratories. [Copyright &y& Elsevier]