The clinical performance of a laboratory test can be described in terms of diagnostic accuracy, or the ability to correctly classify subjects into clinically relevant subgroups. Diagnostic accuracy refers to the quality of the information provided by the classification device and should be distinguished from the usefulness, or actual practical value, of the information. Receiver-operating characteristic (ROC) plots provide a pure index of accuracy by demonstrating the limits of a test's ability to discriminate between alternative states of health over the complete spectrum of operating conditions. Furthermore, ROC plots occupy a central or unifying position in the process of assessing and using diagnostic tools. Once the plot is generated, a user can readily go on to many other activities such as performing quantitative ROC analysis and comparisons of tests, using likelihood ratio to revise the probability of disease in individual subjects, selecting decision thresholds, using logistic-regression analysis, using discriminant-function analysis, or incorporating the tool into a clinical strategy by using decision analysis.

/pdf/receiver-operating-characteristic-roc-plots-a-fundamental-1bsmhsp7j4.pdf

Receiver-operating characteristic (ROC) plots: a fundamental evaluation tool in clinical medicine.

Lionel A. Mandell, Richard G. Wunderink, Antonio Anzueto, John G. Bartlett, G. Douglas Campbell, Nathan C. Dean, Scott F. Dowell, Thomas M. File, Jr. Daniel M. Musher, Michael S. Niederman, Antonio Torres, and Cynthia G. Whitney McMaster University Medical School, Hamilton, Ontario, Canada; Northwestern University Feinberg School of Medicine, Chicago, Illinois; University of Texas Health Science Center and South Texas Veterans Health Care System, San Antonio, and Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine, Houston, Texas; Johns Hopkins University School of Medicine, Baltimore, Maryland; Division of Pulmonary, Critical Care, and Sleep Medicine, University of Mississippi School of Medicine, Jackson; Division of Pulmonary and Critical Care Medicine, LDS Hospital, and University of Utah, Salt Lake City, Utah; Centers for Disease Control and Prevention, Atlanta, Georgia; Northeastern Ohio Universities College of Medicine, Rootstown, and Summa Health System, Akron, Ohio; State University of New York at Stony Brook, Stony Brook, and Department of Medicine, Winthrop University Hospital, Mineola, New York; and Cap de Servei de Pneumologia i Allergia Respiratoria, Institut Clinic del Torax, Hospital Clinic de Barcelona, Facultat de Medicina, Universitat de Barcelona, Institut d’Investigacions Biomediques August Pi i Sunyer, CIBER CB06/06/0028, Barcelona, Spain.

/pdf/infectious-diseases-society-of-america-american-thoracic-1cn65eiqga.pdf

Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults

Extended-spectrum β-lactamases (ESBLs) are a rapidly evolving group of β-lactamases which share the ability to hydrolyze third-generation cephalosporins and aztreonam yet are inhibited by clavulanic acid. Typically, they derive from genes for TEM-1, TEM-2, or SHV-1 by mutations that alter the amino acid configuration around the active site of these β-lactamases. This extends the spectrum of β-lactam antibiotics susceptible to hydrolysis by these enzymes. An increasing number of ESBLs not of TEM or SHV lineage have recently been described. The presence of ESBLs carries tremendous clinical significance. The ESBLs are frequently plasmid encoded. Plasmids responsible for ESBL production frequently carry genes encoding resistance to other drug classes (for example, aminoglycosides). Therefore, antibiotic options in the treatment of ESBL-producing organisms are extremely limited. Carbapenems are the treatment of choice for serious infections due to ESBL-producing organisms, yet carbapenem-resistant isolates have recently been reported. ESBL-producing organisms may appear susceptible to some extended-spectrum cephalosporins. However, treatment with such antibiotics has been associated with high failure rates. There is substantial debate as to the optimal method to prevent this occurrence. It has been proposed that cephalosporin breakpoints for the Enterobacteriaceae should be altered so that the need for ESBL detection would be obviated. At present, however, organizations such as the Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards) provide guidelines for the detection of ESBLs in klebsiellae and Escherichia coli. In common to all ESBL detection methods is the general principle that the activity of extended-spectrum cephalosporins against ESBL-producing organisms will be enhanced by the presence of clavulanic acid. ESBLs represent an impressive example of the ability of gram-negative bacteria to develop new antibiotic resistance mechanisms in the face of the introduction of new antimicrobial agents.

Extended-spectrum beta-lactamases: a clinical update.

Medical practice is constantly changing. The rate of change is accelerating, and physicians can be forgiven if they often find it dizzying. How can physicians learn about new information and innovations, and decide how (if at all) they should modify their practice? Possible sources include summaries from the medical literature (review articles, practice guidelines, consensus statements, editorials, and summary articles in "throwaway" journals); consultation with colleagues who have special expertise; lectures; seminars; advertisements in medical journals; conversations with representatives from pharmaceutical companies; and original articles in journals and journal supplements. Each of these sources of information might be valuable, though each is subject to its own particular biases. 1,2 Problems arise when, as is often the case, these sources of information provide different suggestions about patient care. See also p 2093. Without a way of critically appraising the information they receive, clinicians are relatively helpless in deciding what new information

https://hopkinsmedicine.org/gim/_pdf/jama/17-screening.pdf

Users' Guides to the Medical Literature

Infectious Diseases Society of America.

The prevalence of antibiotic resistance among extended-spectrum beta-lactamase (ESBL)--producing Escherichia coli and Klebsiella pneumoniae has increased markedly in recent years. Thirty-three patients with infection due to ESBL-producing E. coli or K. pneumoniae (case patients) were compared with 66 matched controls. Total prior antibiotic use was the only independent risk factor for ESBL-producing E. coli or K. pneumoniae infection (odds ratio, 1.10; 95% confidence interval, 1.03--1.18; P=.006). Case patients were treated with an effective antibiotic a median of 72 hours after infection was suspected, compared with a median of 11.5 hours after infection was suspected for controls (P<.001). ESBL-producing E. coli or K. pneumoniae infection was associated with a significantly longer duration of hospital stay and greater hospital charges (P=.01 and P<.001, respectively). Finally, many ESBL-producing E. coli and K. pneumoniae isolates were closely related. ESBL-producing E. coli and K. pneumoniae infections have a significant impact on several important clinical outcomes, and efforts to control outbreaks of infection with ESBL-producing E. coli and K. pneumoniae should emphasize judicious use of all antibiotics as well as barrier precautions to reduce spread.

Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae: Risk Factors for Infection and Impact of Resistance on Outcomes

Eighteen types of media, all of which used charcoal yeast extract medium as a base, were tested for their ability to support the growth of a stock strain of Legionella pneumophila. Fifteen of these contained antimicrobial agents. Five antibiotic-containing media which performed best in growing the stock strain were then tested for the ability to grow L. pneumophila from clinical respiratory tract specimens. One of the media, BMPA alpha, which contained cefamandole, polymyxin B, anisomycin, an organic buffer, and alpha-ketoglutarate, performed from contaminated clinical specimens and, in conjunction with an acid wash treatment, facilitated recovery of the bacterium from potable water.

Improved semiselective medium for isolation of Legionella pneumophila from contaminated clinical and environmental specimens.

http://depts.washington.edu/ramakris/lab/sites/default/files/u19/Adams%20et%20al%202011.pdf

Drug tolerance in replicating mycobacteria mediated by a macrophage-induced efflux mechanism.

BACKGROUND
Klebsiella pneumoniae carbapenemase (KPC)–producing K. pneumoniae is an emerging pathogen with serious clinical and infection control implications. To our knowledge, no study has specifically examined risk factors for KPC-producing K. pneumoniae or its impact on mortality.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0195941700038029

Risk Factors and Clinical Impact of Klebsiella pneumoniae Carbapenemase–Producing K. pneumoniae

▪Objective:To determine if the leukocyte esterase and bacterial nitrite rapid dipstick test for urinary tract infection (UTI) is susceptible to spectrum bias (when a diagnostic test has di...

Paul H. Edelstein

Papers

Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae: Risk Factors for Infection and Impact of Resistance on Outcomes

Improved semiselective medium for isolation of Legionella pneumophila from contaminated clinical and environmental specimens.

Drug tolerance in replicating mycobacteria mediated by a macrophage-induced efflux mechanism.

Risk Factors and Clinical Impact of Klebsiella pneumoniae Carbapenemase–Producing K. pneumoniae

Spectrum Bias in the Evaluation of Diagnostic Tests: Lessons from the Rapid Dipstick Test for Urinary Tract Infection