Diagnostic Tests Can Stem the Threat of Antimicrobial Resistance: Infectious Disease Professionals Can Help.

Uptake of existing diagnostics to identify infections more accurately could minimize unnecessary antibiotic use and decrease the growing threat of antibiotic resistance. The Infectious Diseases Society of America (IDSA) and the Presidential Advisory Council on Combating Antibiotic-Resistant Bacteria (PACCARB) agree that, to improve uptake of existing diagnostics, healthcare providers, health systems, and payors all need better clinical and economic outcomes data to support use of diagnostic tests over empiric use of antibiotics, providers need better tools and education about diagnostic tests, and diagnostics developers need federal funding in the absence of a viable diagnostics market. Recommendations from PACCARB and the IDSA are amplified. Incentives for-and challenges to-diagnostics research, development, and uptake are summarized. Advocacy opportunities are given for infectious disease professionals to join the fight against antimicrobial resistance.

Multinational evaluation of the BioFire® FilmArray® Pneumonia plus Panel as compared to standard of care testing.

This study compared standard of care testing (SOC) to BioFire® FilmArray® Pneumonia plus Panel (PNplus). PNplus detects 15 bacteria with semiquantitative log bin values, 7 antibiotic resistance markers, three atypical bacteria (AB), and eight viral classes directly from bronchoalveolar lavage-like specimens (BLS) and sputum-like specimens (SLS). Fifty-two laboratories from 13 European countries and Israel tested 1234 BLS and 1242 SLS with PNplus and SOC. Detection rates and number of pathogens/samples were compared for PNplus pathogens. PNplus bin values and SOC quantities were compared. Three thousand two hundred sixty-two bacteria in PNplus were detected by PNplus and/or SOC. SOC detected 57.1% compared to 95.8% for PNplus (p ≤ 0.0001). PNplus semiquantitative bin values were less than SOC, equal to SOC, or greater than SOC in 5.1%, 25.4%, and 69.6% of results, respectively. PNplus bin values were on average ≥ 1 log than SOC values (58.5% 1-2 logs; 11.0% 3-4 logs). PNplus identified 98.2% of MRSA and SOC 55.6%. SOC detected 73/103 AB (70.9%) and 134/631 viruses (21.2%). PNplus detected 93/103 AB (90.3%) and 618/631 viruses (97.9%) (p ≤ 0.0001). PNplus and SOC mean number of pathogens/samples were 1.99 and 1.44, respectively. All gram-negative resistance markers were detected. PNplus and SOC results were fully or partially concordant for 49.1% and 26.4% of specimens, respectively. PNplus was highly sensitive and detected more potential pneumonia pathogens than SOC. Semiquantification may assist in understanding pathogen significance. As PNplus generates results in approximately 1 h, PNplus has potential to direct antimicrobial therapy in near real time and improve antimicrobial stewardship and patient outcomes.

Practical Guidance for Clinical Microbiology Laboratories: Viruses Causing Acute Respiratory Tract Infections.

Respiratory viral infections are associated with a wide range of acute syndromes and infectious disease processes in children and adults worldwide. Many viruses are implicated in these infections, and these viruses are spread largely via respiratory means between humans but also occasionally from animals to humans. This article is an American Society for Microbiology (ASM)-sponsored Practical Guidance for Clinical Microbiology (PGCM) document identifying best practices for diagnosis and characterization of viruses that cause acute respiratory infections and replaces the most recent prior version of the ASM-sponsored Cumitech 21 document, Laboratory Diagnosis of Viral Respiratory Disease, published in 1986. The scope of the original document was quite broad, with an emphasis on clinical diagnosis of a wide variety of infectious agents and laboratory focus on antigen detection and viral culture. The new PGCM document is designed to be used by laboratorians in a wide variety of diagnostic and public health microbiology/virology laboratory settings worldwide. The article provides guidance to a rapidly changing field of diagnostics and outlines the epidemiology and clinical impact of acute respiratory viral infections, including preferred methods of specimen collection and current methods for diagnosis and characterization of viral pathogens causing acute respiratory tract infections. Compared to the case in 1986, molecular techniques are now the preferred diagnostic approaches for the detection of acute respiratory viruses, and they allow for automation, high-throughput workflows, and near-patient testing. These changes require quality assurance programs to prevent laboratory contamination as well as strong preanalytical screening approaches to utilize laboratory resources appropriately. Appropriate guidance from laboratorians to stakeholders will allow for appropriate specimen collection, as well as correct test ordering that will quickly identify highly transmissible emerging pathogens.

Molecular Testing for Acute Respiratory Tract Infections: Clinical and Diagnostic Recommendations From the IDSA's Diagnostics Committee.

The clinical signs and symptoms of acute respiratory tract infections (RTIs) are not pathogen specific. Highly sensitive and specific nucleic acid amplification tests have become the diagnostic reference standard for viruses, and translation of bacterial assays from basic research to routine clinical practice represents an exciting advance in respiratory medicine. Most recently, molecular diagnostics have played an essential role in the global health response to the novel coronavirus pandemic. How best to use newer molecular tests for RTI in combination with clinical judgment and traditional methods can be bewildering given the plethora of available assays and rapidly evolving technologies. Here, we summarize the current state of the art with respect to the diagnosis of viral and bacterial RTIs, provide a practical framework for diagnostic decision making using selected patient-centered vignettes, and make recommendations for future studies to advance the field.

Economic analysis of rapid multiplex polymerase chain reaction testing for meningitis/encephalitis in adult patients.

PURPOSE: Many patients with suspected meningitis do not require hospitalization yet are admitted, often resulting in unnecessary care and additional cost. We assessed the possible economic impact of a rapid multiplex test for suspected adult community-acquired meningitis/encephalitis. METHODS: A model simulated diagnosis, clinical decisions, resource use/costs of standard of care (SOC) and two cerebrospinal fluid (CSF) testing strategies using the FDA-cleared BioFire® FilmArray® System (FA) which provides results in approximately one hour. RESULTS: Pathogens detected by FA caused approximately 74% of cases, 97% of which would be accurately diagnosed with FA. False positives and false negatives more often led to extended/unnecessary admission than inappropriate discharge/missed admission. Mean cost per case ranged from 16829 to 20791. A strategy of testing all suspected cases yielded greater savings (2213/case) than testing only those with abnormal CSF (812/case) and both were less expensive than SOC. CONCLUSION: This economic analysis demonstrates that FA can inform more appropriate clinician decisions resulting in cost savings with greater economic benefits achievable with syndromic testing of all cases, rather than SOC or targeted syndromic testing.

Epidemiology of Meningitis and Encephalitis in the United States, 2011-2014.

BACKGROUND: Large epidemiological studies evaluating the etiologies, management decisions, and outcomes of adults with meningitis or encephalitis in the United States (US) are lacking. METHODS: Adult patients (≥18 years) with meningitis or encephalitis by International Classification of Diseases, Ninth Revision codes available in the Premier Healthcare Database during 2011-2014 were analyzed. RESULTS: A total of 26429 patients with meningitis or encephalitis were identified. The median age was 43 years; 53% were female. The most common etiology was enterovirus (13463 [51.6%]), followed by unknown (4944 [21.4%]), bacterial meningitis (3692 [14.1%]), herpes simplex virus (2184 [8.3%]), noninfectious (921 [3.5%]), fungal (720 [2.7%]), arboviruses (291 [1.1%]), and other viruses (214 [0.8%]). Empiric antibiotics, antivirals, and antifungals were administered in 85.8%, 53.4%, and 7.8%, respectively, and varied by etiologies. Adjunctive steroids were utilized in 15.9% of all patients and in 39.3% of patients with pneumococcal meningitis, with an associated decrease in mortality (6.67% vs 12.5%, P = .0245). The median length of stay was 4 days, with the longest duration in those with fungal (13), arboviral (10), and bacterial meningitis (7). Overall inpatient mortality was 2.9% and was higher in those with bacterial (8.2%), fungal (8.2%), or arboviral (8.9%) disease. Overall readmission rate at 30 days was 3.2%; patients with arboviral (12.7%), bacterial (6.7%), and fungal (5.4%) etiologies had higher rates. CONCLUSIONS: Viruses are the most common cause of meningitis and encephalitis in the United States and are treated with antibiotic therapy in the majority of cases. Adjunctive steroid treatment is underutilized in pneumococcal meningitis, where it has shown to decrease mortality.

Maintaining Life-saving Testing for Patients With Infectious Diseases: Infectious Diseases Society of America, American Society for Microbiology, and Pan American Society for Clinical Virology Recommendations on the Regulation of Laboratory-developed Tests.

In 2014, the US Food and Drug Administration (FDA) proposed to regulate laboratory-developed tests (LDTs)-diagnostics designed, manufactured, and used within a single laboratory. The Infectious Diseases Society of America, the American Society for Microbiology, and the Pan American Society for Clinical Virology recognize that the FDA is committed to protecting patients. However, our societies are concerned that the proposed regulations will limit access to testing and negatively impact infectious diseases (ID) LDTs. In this joint commentary, our societies discuss why LDTs are critical for ID patient care, hospital infection control, and public health responses. We also highlight how the FDA's proposed regulation of LDTs could impair patient access to life-saving tests and stifle innovation in ID diagnostics. Finally, our societies make specific recommendations for the FDA's consideration to reduce the burden of the proposed new rules on clinical laboratories and protect patients' access to state-of-the art, quality LDTs.

Genital Epstein Barr Virus is associated with higher prevalence and persistence of anal human papillomavirus in HIV-infected men on antiretroviral therapy.

BACKGROUND: Epstein Barr virus (EBV) and human papillomavirus (HPV) can co-exist in pharyngeal and cervical malignancies. However, the natural history and factors associated with persistent HPV infection among HIV-infected men who have sex with men (MSM) are unclear. METHODS: 131 HIV-infected MSM were followed for 48 weeks and screened for multiple co-infections, including seminal EBV DNA and high risk (HR)-HPV messenger RNA (mRNA) at several sites (semen, anal, pharynx). Primary analysis tested if seminal EBV shedding was associated with increased prevalence of HR-HPV at baseline using univariate tests and multivariable logistic regression. In participants with detectable anal HR-HPV at baseline, we tested if presence of seminal EBV shedding at baseline was also predictive of reduced HR-HPV clearance by log-rank test (over 48 weeks of follow-up). RESULTS: Baseline prevalence of HR-HPV was: anal 44% (N = 54/121); pharynx 3.8% (N = 5/131); semen 7.1% (N = 7/98). Seminal EBV shedding was present in 28% of participants and was associated with more than double the prevalence of detectable anal HR-HPV mRNA (71.4% for EBV shedders versus 33.3% for non-shedders, p < 0.01). In participants with detectable anal HR-HPV at baseline, we found increased persistence of HR-HPV over 48 weeks of follow-up (measured as time to first negative HR-HPV test in the EBV shedding group (p < 0.01). CONCLUSIONS: Seminal EBV shedding was associated with an increased risk of having detectable anal HR-HPV in a cohort of HIV-infected MSM on suppressive ART. Future studies should examine if co-infection with EBV and HR-HPV may act synergistically in pathogenesis of anal cancer in HIV-infected individuals.

Can newly developed, rapid immunochromatographic antigen detection tests be reliably used for the laboratory diagnosis of influenza virus infections?

Five years ago, the Point-Counterpoint series was launched. The initial article asked about the role of rapid immunochromatographic antigen testing in the diagnosis of influenza A virus 2009 H1N1 infection (D. F. Welch and C. C. Ginocchio, J Clin Microbiol 48:22-25, 2010, http://dx.doi.org/10.1128/JCM.02268-09). Since that article, not only have major changes been made in immunochromatographic antigen detection (IAD) testing for the influenza viruses, but there has also been rapid development of commercially available nucleic acid amplification tests (NAATs) for influenza virus detection. Further, a novel variant of influenza A, H7N9, has emerged in Asia, and H5N1 is also reemergent. In that initial article, the editor of this series, Peter Gilligan, identified two issues that required further consideration. One was how well IAD tests worked in clinical settings, especially in times of antigen drift and shift. The other was the role of future iterations of influenza NAATs and whether this testing would be available in a community hospital setting. James Dunn, who is Director of Medical Microbiology and Virology at Texas Children's Hospital, has extensive experience using IAD tests for diagnosing influenza. He will discuss the application and value of these tests in influenza diagnosis. Christine Ginocchio, who recently retired as the Senior Medical Director, Division of Infectious Disease Diagnostics, North Shore-LIJ Health System, and now is Vice President for Global Microbiology Affairs at bioMérieux, Durham, NC, wrote the initial counterpoint in this series, where she advocated the use of NAATs for influenza diagnosis. She will update us on the commercially available NAAT systems and explain what their role should be in the diagnosis of influenza infection.

Assessment of Reproducibility of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Bacterial and Yeast Identification.

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has revolutionized the identification of clinical bacterial and yeast isolates. However, data describing the reproducibility of MALDI-TOF MS for microbial identification are scarce. In this study, we show that MALDI-TOF MS-based microbial identification is highly reproducible and can tolerate numerous variables, including differences in testing environments, instruments, operators, reagent lots, and sample positioning patterns. Finally, we reveal that samples of bacterial and yeast isolates prepared for MALDI-TOF MS identification can be repeatedly analyzed without compromising organism identification.

Incidence of extended-spectrum-ß-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates that test susceptible to cephalosporins and aztreonam by the revised CLSI breakpoints.

The incidence of aztreonam and cephalosporin susceptibility, determined using the revised CLSI breakpoints, for extended-spectrum-ß-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae isolates was evaluated. Our analysis showed that results for aztreonam and/or ≥1 cephalosporin were reported as susceptible or intermediate for 89.2% of ESBL-producing E coli isolates (569/638 isolates) and 67.7% of ESBL-producing K. pneumoniae isolates (155/229 isolates).

Septic arthritis of a native knee joint due to Corynebacterium striatum.

We report a case of septic arthritis of a native knee joint due to Corynebacterium striatum, a rare and unusual cause of septic arthritis of native joints. The isolate was identified by a combination of phenotypic, mass spectrometric, and nucleic acid-based assays and exhibited high-level resistance to most antimicrobials.

Better tests, better care: improved diagnostics for infectious diseases.

In this IDSA policy paper, we review the current diagnostic landscape, including unmet needs and emerging technologies, and assess the challenges to the development and clinical integration of improved tests. To fulfill the promise of emerging diagnostics, IDSA presents recommendations that address a host of identified barriers. Achieving these goals will require the engagement and coordination of a number of stakeholders, including Congress, funding and regulatory bodies, public health agencies, the diagnostics industry, healthcare systems, professional societies, and individual clinicians.

Multiplex identification of gram-positive bacteria and resistance determinants directly from positive blood culture broths: evaluation of an automated microarray-based nucleic acid test.

BACKGROUND: A multicenter study was conducted to evaluate the diagnostic accuracy (sensitivity and specificity) of the Verigene Gram-Positive Blood Culture Test (BC-GP) test to identify 12 Gram-positive bacterial gene targets and three genetic resistance determinants directly from positive blood culture broths containing Gram-positive bacteria. METHODS AND FINDINGS: 1,252 blood cultures containing Gram-positive bacteria were prospectively collected and tested at five clinical centers between April, 2011 and January, 2012. An additional 387 contrived blood cultures containing uncommon targets (e.g., Listeria spp., S. lugdunensis, vanB-positive Enterococci) were included to fully evaluate the performance of the BC-GP test. Sensitivity and specificity for the 12 specific genus or species targets identified by the BC-GP test ranged from 92.6%-100% and 95.4%-100%, respectively. Identification of the mecA gene in 599 cultures containing S. aureus or S. epidermidis was 98.6% sensitive and 94.3% specific compared to cefoxitin disk method. Identification of the vanA gene in 81 cultures containing Enterococcus faecium or E. faecalis was 100% sensitive and specific. Approximately 7.5% (87/1,157) of single-organism cultures contained Gram-positive bacteria not present on the BC-GP test panel. In 95 cultures containing multiple organisms the BC-GP test was in 71.6% (68/95) agreement with culture results. Retrospective analysis of 107 separate blood cultures demonstrated that identification of methicillin resistant S. aureus and vancomycin resistant Enterococcus spp. was completed an average of 41.8 to 42.4 h earlier using the BC-GP test compared to routine culture methods. The BC-GP test was unable to assign mecA to a specific organism in cultures containing more than one Staphylococcus isolate and does not identify common blood culture contaminants such as Micrococcus, Corynebacterium, and Bacillus. CONCLUSIONS: The BC-GP test is a multiplex test capable of detecting most leading causes of Gram-positive bacterial blood stream infections as well as genetic markers of methicillin and vancomycin resistance directly from positive blood cultures.

Identification of endogenous Coccidioides posadasii contamination of commercial primary rhesus monkey kidney cells.

Here we describe the identification of endogenous Coccidioides posadasii contamination in commercial rhesus monkey kidney (RhMK) cells and the subsequent nationwide alert that reduced the risk of laboratory exposure. This extraordinary event highlights the necessity for laboratories to remain vigilant in the use of appropriate biosafety procedures, particularly when working with unknown pathogens.

Multicenter evaluation of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Gram-positive aerobic bacteria.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting.

Multicenter study evaluating the Vitek MS system for identification of medically important yeasts.

The optimal management of fungal infections is correlated with timely organism identification. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is revolutionizing the identification of yeasts isolated from clinical specimens. We present a multicenter study assessing the performance of the Vitek MS system (bioMérieux) in identifying medically important yeasts. A collection of 852 isolates was tested, including 20 Candida species (626 isolates, including 58 C. albicans, 62 C. glabrata, and 53 C. krusei isolates), 35 Cryptococcus neoformans isolates, and 191 other clinically relevant yeast isolates; in total, 31 different species were evaluated. Isolates were directly applied to a target plate, followed by a formic acid overlay. Mass spectra were acquired using the Vitek MS system and were analyzed using the Vitek MS v2.0 database. The gold standard for identification was sequence analysis of the D2 region of the 26S rRNA gene. In total, 823 isolates (96.6%) were identified to the genus level and 819 isolates (96.1%) were identified to the species level. Twenty-four isolates (2.8%) were not identified, and five isolates (0.6%) were misidentified. Misidentified isolates included one isolate of C. albicans (n = 58) identified as Candida dubliniensis, one isolate of Candida parapsilosis (n = 73) identified as Candida pelliculosa, and three isolates of Geotrichum klebahnii (n = 6) identified as Geotrichum candidum. The identification of clinically relevant yeasts using MS is superior to the phenotypic identification systems currently employed in clinical microbiology laboratories.

Multiplex real-time PCR for detection of an epidemic KPC-producing Klebsiella pneumoniae ST258 clone.

We describe a multiplex real-time PCR assay capable of identifying both the epidemic Klebsiella pneumoniae ST258 clone and bla(KPC) carbapenemase genes in a single reaction. The assay displayed excellent sensitivity (100%) and specificity (100%) for identification of ST258 clone and bla(KPC) in a collection of 75 K. pneumoniae isolates comprising 41 sequence types. Our results suggest that this assay is an effective tool for surveillance of this clone among carbapenem-resistant K. pneumoniae clinical isolates.

Novel strategies to diagnose prosthetic or native bone and joint infections.

INTRODUCTION: Bone and Joint Infections (BJI) are medically important, costly and occur in native and prosthetic joints. Arthroplasties will increase significantly in absolute numbers over time as well as the incidence of Prosthetic Joint Infections (PJI). Diagnosis of BJI and PJI is sub-optimal. The available diagnostic tests have variable effectiveness, are often below standard in sensitivity and/or specificity, and carry significant contamination risks during the collection of clinical samples. Improvement of diagnostics is urgently needed. AREAS COVERED: We provide a narrative review on current and future diagnostic microbiology technologies. Pathogen identification, antibiotic resistance detection, and assessment of the epidemiology of infections via bacterial typing are considered useful for improved patient management. We confirm the continuing importance of culture methods and successful introduction of molecular, mass spectrometry-mediated and next-generation genome sequencing technologies. The diagnostic algorithms for BJI must be better defined, especially in the context of diversity of both disease phenotypes and clinical specimens rendered available. EXPERT OPINION: Whether interventions in BJI or PJI are surgical or chemo-therapeutic (antibiotics and bacteriophages included), prior sensitive and specific pathogen detection remains a therapy-substantiating necessity. Innovative tests for earlier and more sensitive and specific detection of bacterial pathogens in BJI are urgently needed.