Diagnostic Accuracy of a Bacterial and Viral Biomarker Point-of-Care Test in the Outpatient Setting.

Importance: Acute respiratory infections (ARIs) account for most outpatient visits. Discriminating bacterial vs viral etiology is a diagnostic challenge with therapeutic implications. Objective: To investigate whether FebriDx, a rapid, point-of-care immunoassay, can differentiate bacterial- from viral-associated host immune response in ARI through measurement of myxovirus resistance protein A (MxA) and C-reactive protein (CRP) from finger-stick blood. Design, Setting, and Participants: This diagnostic study enrolled adults and children who were symptomatic for ARI and individuals in a control group who were asymptomatic between October 2019 and April 2021. Included participants were a convenience sample of patients in outpatient settings (ie, emergency department, urgent care, and primary care) who were symptomatic, aged 1 year or older, and had suspected ARI and fever within 72 hours. Individuals with immunocompromised state and recent vaccine, antibiotics, stroke, surgery, major burn, or myocardial infarction were excluded. Of 1685 individuals assessed for eligibility, 259 individuals declined participation, 718 individuals were excluded, and 708 individuals were enrolled (520 patients with ARI, 170 patients without ARI, and 18 individuals who dropped out). Exposures: Bacterial and viral immunoassay testing was performed using finger-stick blood. Results were read at 10 minutes, and treating clinicians and adjudicators were blinded to results. Main Outcomes and Measures: Bacterial- or viral-associated systemic host response to an ARI as determined by a predefined comparator algorithm with adjudication classified infection etiology. Results: Among 520 participants with ARI (230 male patients [44.2%] and 290 female patients [55.8%]; mean [SD] age, 35.3 [17.7] years), 24 participants with missing laboratory information were classified as unknown (4.6%). Among 496 participants with a final diagnosis, 73 individuals (14.7%) were classified as having a bacterial-associated response, 296 individuals (59.7%) as having a viral-associated response, and 127 individuals (25.6%) as negative by the reference standard. The bacterial and viral test correctly classified 68 of 73 bacterial infections, demonstrating a sensitivity of 93.2% (95% CI, 84.9%-97.0%), specificity of 374 of 423 participants (88.4% [95% CI, 85.0%-91.1%]), positive predictive value (PPV) of 68 of 117 participants (58.1% [95% CI, 49.1%-66.7%), and negative predictive value (NPV) of 374 of 379 participants (98.7% [95% CI, 96.9%-99.4%]).The test correctly classified 208 of 296 viral infections, for a sensitivity of 70.3% (95% CI, 64.8%-75.2%), a specificity of 176 of 200 participants (88.0% [95% CI, 82.8%-91.8%]), a PPV of 208 of 232 participants (89.7% [95% CI, 85.1%-92.9%]), and an NPV of 176 of 264 participants (66.7% [95% CI, 60.8%-72.1%]). Conclusions and Relevance: In this study, a rapid diagnostic test demonstrated diagnostic performance that may inform clinicians when assessing for bacterial or viral etiology of ARI symptoms.

Multi-tiered screening and diagnosis strategy for COVID-19: a model for sustainable testing capacity in response to pandemic.

Coronavirus disease 2019 (COVID-19), caused by novel enveloped single stranded RNA coronavirus (SARS-CoV-2), is responsible for an ongoing global pandemic. While other countries deployed widespread testing as an early mitigation strategy, the U.S. experienced delays in development and deployment of organism identification assays. As such, there is uncertainty surrounding disease burden and community spread, severely hampering containment efforts. COVID-19 illuminates the need for a tiered diagnostic approach to rapidly identify clinically significant infections and reduce disease spread. Without the ability to efficiently screen patients, hospitals are overwhelmed, potentially delaying treatment for other emergencies. A multi-tiered, diagnostic strategy incorporating a rapid host immune response assay as a screening test, molecular confirmatory testing and rapid IgM/IgG testing to assess benefit from quarantine/further testing and provide information on population exposure/herd immunity would efficiently evaluate potential COVID-19 patients. Triaging patients within minutes with a fingerstick rather than hours/days after an invasive swab is critical to pandemic response as reliance on the existing strategy is limited by assay accuracy, time to results, and testing capacity. Early screening and triage is achievable from the outset of a pandemic with point-of-care host immune response testing which will improve response time to clinical and public health actions.Key messagesDelayed testing deployment has led to uncertainty surrounding overall disease burden and community spread, severely hampering public health containment and healthcare system preparation efforts.A multi-tiered testing strategy incorporating rapid, host immune point-of-care tests can be used now and for future pandemic planning by effectively identifying patients at risk of disease thereby facilitating quarantine earlier in the progression of the outbreak during the weeks and months it can take for pathogen specific confirmatory tests to be developed, validated and manufactured in sufficient quantities.The ability to triage patients at the point of care and support the guidance of medical and therapeutic decisions, for viral isolation or confirmatory testing or for appropriate treatment of COVID-19 and/or bacterial infections, is a critical component to our national pandemic response and there is an urgent need to implement the proposed strategy to combat the current outbreak.

A prospective, multi-centre US clinical trial to determine accuracy of FebriDx point-of-care testing for acute upper respiratory infections with and without a confirmed fever.

BACKGROUND: FebriDx is a 10-minute disposable point-of-care test designed to identify clinically significant systemic host immune responses and aid in the differentiation of bacterial and viral respiratory infection by simultaneously detecting C-reactive protein (CRP) and myxovirus resistance protein A (MxA) from a fingerstick blood sample. FebriDx diagnostic accuracy was evaluated in the emergency room and urgent care setting. METHODS: A prospective, multicentre, observational cohort study of acute upper respiratory tract infections (URIs), with and without a confirmed fever at the time of enrolment, was performed to evaluate the diagnostic accuracy of FebriDx to identify clinically significant bacterial infection with host response and acute pathogenic viral infection. The reference method consisted of an algorithm with physician override that included bacterial cell culture, respiratory PCR panels for viral and atypical pathogens, procalcitonin, and white blood cell count. RESULTS: Among 220 patients enrolled, 100% reported fever 100.5°F within the last 72 hours while 55% had a measured hyperthermia (T > 100.4) at the time of enrolment. FebriDx demonstrated a sensitivity of 95% (95% CI: 77-100%), specificity of 94% (88-98%), PPV of 76% (59-87%), and a NPV of 99% (93-100%). CONCLUSION: FebriDx may identify clinically significant bacterial URI's and supports outpatient antibiotic decisions. Key messages FebriDx is an outpatient POC test designed to identify a clinically significant systemic host immune response and aid in the differentiation of viral and bacterial infection through rapid measurement of MxA and CRP from a fingerstick blood sample. FebriDx test was determined to be an accurate test, with a 85% sensitivity, 93% specificity and 97% NPV to rule out bacterial infection for any patient presenting with symptoms and reported fever within the prior 3 days, and when confirming fever (hyperthermia) at the time of testing, the test was even more sensitive (95%) and specific (94%) with a 99% NPV. FebriDx may support antibiotic stewardship by rapidly identifying clinically significant bacterial URIs.

Presence or absence of ocular surface inflammation directs clinical and therapeutic management of dry eye.

BACKGROUND: The presence of clinically significant inflammation has been confirmed in the tears of 40%-65% of patients with symptoms of dry eye. Ocular surface inflammation may lead to tear film instability, epithelial cell irregularities, and permeability, resulting in chronic symptomatic pain and fluctuating vision as well as negative surgical outcomes. PATIENTS AND METHODS: A retrospective single center medical chart review of 100 patients was conducted. All patients were tested with the InflammaDry test to determine if patients exhibited elevated levels of matrix metalloproteinase 9 (MMP-9). InflammaDry-positive patients were started on a combination of cyclosporine 0.05% twice daily, 2,000-4,000 mg oral omega-3 fatty acids, and frequent artificial tear replacement. InflammaDry-negative patients were started on 2,000-4,000 mg of oral omega-3 fatty acids and frequent artificial tear replacement. Each patient was retested at ~90 days. A symptom questionnaire was performed at the initial visit and at 90 days. RESULTS: 60% of the patients with dry eye symptoms tested positive for elevated MMP-9 at the initial visit. 78% of all patients returned for follow-up at ~90 days including 80% (48/60) of the previously InflammaDry-positive patients and 75% (30/40) of the previously InflammaDry-negative patients. A follow-up symptom questionnaire reported at least 75% symptomatic improvement in 65% (31/48) of the originally InflammaDry-positive patients and in 70% (21/30) of the initially InflammaDry-negative patients. Symptomatic improvement of at least 50% was reported in 85% (41/48) of previously InflammaDry-positive patients and 86% (26/30) of previously InflammaDry-negative patients. Following treatment, 54% (26/48) of previously InflammaDry-positive patients converted to a negative InflammaDry result. CONCLUSION: Identifying which symptomatic dry eye patients have underlying inflammation may predict patient responses to treatment and influence clinical management strategies.

Evaluation of a combined MxA and CRP point-of-care immunoassay to identify viral and/or bacterial immune response in patients with acute febrile respiratory infection.

BACKGROUND: Challenges in the clinical differentiation of viral and/or bacterial respiratory infection lead to the misappropriation of antibiotics and increased healthcare costs. A tool to facilitate rapid and accurate point-of-care (POC) differentiation is needed. METHODS AND FINDINGS: A prospective, single center, blinded, observational clinical trial was conducted at Beth Israel Deaconess Medical Center from December 2012 to August 2013 to determine the accuracy of a POC immunoassay to identify a clinically significant immune response to viral and/or bacterial infection. Sixty patients with acute febrile respiratory infection (19 pharyngitis and 41 lower respiratory tract infection [LRTI]) were enrolled. Participants provided fingerstick blood for immunoassay testing (myxovirus A [MxA] and c-reactive protein [CRP]) and four oropharyngeal samples for viral PCR and routine bacterial cell culture. A venous blood sample was collected. An ELISA was used to measure CRP and MxA. Paired serological testing was used to confirm atypical bacteria. A urine sample was provided for Streptococcus and Legionella antigen testing. Patients with suspected LRTI had sputum and blood cultures, chest X-ray, and WBC count measured. Viral infection was confirmed if oropharyngeal PCR was positive for viral pathogens. Bacterial infection was confirmed in positive throat or sputum cultures. Elevated immunoglobulin M antibodies or twofold increase in IgG antibodies between acute and convalescent phase indicated atypical bacteria. Positive Streptococcus or Legionella urine antigen assays also confirmed bacterial infection. The immunoassay correctly categorized subjects as 92% (22/24) negative, 80% (16/20) with bacterial infection, and 70% (7/10) with viral infection. CONCLUSIONS: The interplay between an MxA value and a semi-quantitative CRP value can aid in the differentiation of infectious etiology. In isolation, neither MxA nor CRP alone is sensitive or specific. However, the pattern of results in a rapid immunoassay provides a sensitive and specific method to differentiate acute febrile respiratory infections. This diagnostic information may help reduce antibiotic misuse and resistance and lower healthcare costs.

Prospective, multicenter, clinical evaluation of point-of-care matrix metalloproteinase-9 test for confirming dry eye disease.

PURPOSE: The aim of this study was to determine the negative and positive agreement of a point-of-care matrix metalloproteinase-9 test in confirming the diagnosis of dry eye and to evaluate the ease of use by untrained ophthalmic technicians. METHODS: The study was a prospective, sequential, masked, clinical trial with 4 clinical trial sites. The InflammaDry test was compared with the clinical assessment of tear break-up time, Schirmer tear testing, and corneal staining for the confirmation of dry eye, both with and without the inclusion of the Ocular Surface Disease Index (OSDI), as a confirmatory test. RESULTS: The study enrolled 237 patients. If the OSDI is included in the definition for mild dry eye, the InflammaDry test was shown to have a total positive agreement of 81% (127/157) and a negative agreement of 98% (78/80). The removal of the OSDI shifted the categorization of 11 patients previously considered positive for dry eye to become categorized as negative for dry eye. If the OSDI is excluded from the definition of dry eye, the InflammaDry test demonstrates a positive agreement of 86% (126/146) and a negative agreement of 97% (88/91) against the clinical assessment. CONCLUSIONS: The InflammaDry test demonstrates a high positive and negative agreement for confirming suspected dry eye disease. In addition, the test was safely and effectively performed by untrained operators. These findings support the intended use of the InflammaDry test as an aid in the diagnosis of dry eye.

Sensitivity and specificity of the AdenoPlus test for diagnosing adenoviral conjunctivitis.

OBJECTIVE: To compare the clinical sensitivity and specificity of the AdenoPlus test with those of both viral cell culture (CC) with confirmatory immunofluorescence assay (IFA) and polymerase chain reaction (PCR) at detecting the presence of adenovirus in tear fluid. METHODS: A prospective, sequential, masked, multicenter clinical trial enrolled 128 patients presenting with a clinical diagnosis of acute viral conjunctivitis from a combination of 8 private ophthalmology practices and academic centers. Patients were tested with AdenoPlus, CC-IFA, and PCR to detect the presence of adenovirus. MAIN OUTCOME MEASURES: The sensitivity and specificity of AdenoPlus were assessed for identifying cases of adenoviral conjunctivitis. RESULTS: Of the 128 patients enrolled, 36 patients' results were found to be positive by either CC-IFA or PCR and 29 patients' results were found to be positive by both CC-IFA and PCR. When compared only with CC-IFA, AdenoPlus showed a sensitivity of 90% (28/31) and specificity of 96% (93/97). When compared only with PCR, AdenoPlus showed a sensitivity of 85% (29/34) and specificity of 98% (89/91). When compared with both CC-IFA and PCR, AdenoPlus showed a sensitivity of 93% (27/29) and specificity of 98% (88/90). When compared with PCR, CC-IFA showed a sensitivity of 85% (29/34) and specificity of 99% (90/91). CONCLUSION: AdenoPlus is sensitive and specific at detecting adenoviral conjunctivitis. APPLICATION TO CLINICAL PRACTICE: An accurate and rapid in-office test can prevent the misdiagnosis of adenoviral conjunctivitis that leads to the spread of disease, unnecessary antibiotic use, and increased health care costs. Additionally, AdenoPlus may help a clinician make a more informed treatment decision regarding the use of novel therapeutics. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00921895.

Sensitivity and specificity of a point-of-care matrix metalloproteinase 9 immunoassay for diagnosing inflammation related to dry eye.

OBJECTIVES: To determine the clinical sensitivity, specificity, negative predictive value, and positive predictive value of a rapid point-of-care diagnostic test to detect elevated matrix metalloproteinase 9 levels (InflammaDry). METHODS: In a prospective, sequential, masked, multicenter clinical trial, InflammaDry was performed on 206 patients: 143 patients with clinical signs and symptoms of dysfunctional tear syndrome (dry eyes) and 63 healthy individuals serving as controls. Participants were assessed as healthy controls or for a clinical diagnosis of dry eye using the Ocular Surface Disease Index, Schirmer tear test, tear breakup time, and keratoconjunctival staining. MAIN OUTCOME MEASURES: The sensitivity and specificity of InflammaDry were compared with clinical assessment. RESULTS: InflammaDry showed sensitivity of 85% (in 121 of 143 patients), specificity of 94% (59 of 63), negative predictive value of 73% (59 of 81), and positive predictive value of 97% (121 of 125). CONCLUSION: Compared with clinical assessment, InflammaDry is sensitive and specific in diagnosing dry eye. APPLICATION TO CLINICAL PRACTICE: Dry eye is often underdiagnosed resulting from poor communication between the clinical assessment of dry eye severity between clinicians and patients. This often leads to a lack of effective treatment. Matrix metalloproteinase 9 is an inflammatory biomarker that has been shown to be elevated in the tears of patients with dry eyes. The ability to accurately detect elevated matrix metalloproteinase 9 levels may lead to earlier diagnosis, more appropriate treatment, and better management of ocular surface disease. Preoperative and perioperative management of inflammation related to dry eyes may reduce dry eyes that develop after laser in situ keratomileusis, improve wound healing, and reduce flap complications. Recognition of inflammation may allow for targeted perioperative therapeutic management of care for patients who undergo cataract and refractive surgery and improve outcomes. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01313351.

A 10-minute point-of-care assay for detection of blood protein adducts resulting from low level exposure to organophosphate nerve agents.

The OrganoTox test is a rapid, point-of-care assay capable of detecting clinically relevant organophosphate (OP) poisoning after low-level exposure to sarin, soman, tabun, or VX chemical nerve agents. The test utilizes either a finger stick peripheral blood sample or plasma specimen. While high-level nerve agent exposure can quickly lead to death, low-level exposure produces vague, nondescript signs and symptoms that are not easily clinically differentiated from other conditions. In initial testing, the OrganoTox test was used to detect the presence of blood protein-nerve agent adducts in exposed blood samples. In order to mimic the in vivo exposure as closely as possible, nerve agents stored in organic solvents were spiked in minute quantities into whole blood samples. For performance testing, 40 plasma samples were spiked with sarin, soman, tabun, or VX and 10 normal plasma samples were used as the negative control. The 40 nerve agent-spiked plasma samples included 10 replicates of each agent. At the clinically relevant low-level exposure of 10 ng/ml, the OrganoTox test demonstrated 100% sensitivity for soman, tabun, and VX and 80% sensitivity for sarin. The OrganoTox test demonstrated greater than 97% specificity with 150 blood samples obtained from healthy adults. No cross-reactivity or interference from pesticide precursor compounds was found. A rapid test for nerve agent exposure will help identify affected patients earlier in the clinical course and trigger more appropriate medical management in a more timely manner.

MMP-9 and the perioperative management of LASIK surgery.

PURPOSE OF REVIEW: Hyperosmolarity is a central mechanism causing ocular surface inflammation and eye irritation in typical patients suffering from tear dysfunction. Tear composition in dry eyes, or dysfunctional tear syndrome, may destabilize the tear film and cause ocular surface epithelial disease. Increased activity of matrix metalloproteinases (MMPs), especially MMP-9, plays a critical role in wound healing and inflammation and is primarily responsible for the pathologic alterations to the ocular surface that leads to a dysfunctional tear state. RECENT FINDINGS: Altered corneal epithelial barrier function is the cause for ocular irritation and visual morbidity in dry eye disease. The increased MMP-9 activity in dry eyes may contribute to deranged corneal epithelial barrier function, increased corneal epithelial desquamation, and corneal surface irregularity. SUMMARY: Dry eye is one of the most common complications of photorefractive keratectomy and laser in-situ keratomileusis (LASIK). LASIK has both a neurotrophic effect on the cornea and leads to a physical change in corneal shape that results in a change in tear dynamics, leading to ocular surface desiccation. The reduction in tear function after LASIK may induce an increase in osmolarity and consequently raise the concentration of proinflammatory cytokines and MMP-9 in the tear film, which results in dry eyes and insufficient attachment between the corneal flap and the corneal bed. Appropriate diagnosis and management of dysfunctional tear syndrome may lead to less postoperative LASIK complications.

The prevalence of adenoviral conjunctivitis at the Wills Eye Hospital Emergency Room.

OBJECTIVE: The aim of this study was to evaluate the prevalence of adenoviral conjunctivitis by analyzing data from a prospective clinical study of 50 consecutive patients presenting to the Wills Eye Hospital Emergency Room (WEH ER) with a clinical diagnosis of infectious conjunctivitis from July 2003 to October 2003. METHODS: The polymerase chain reaction (PCR) was used to evaluate all cases of clinically diagnosed infectious conjunctivitis. Based on the laboratory findings, the prevalence of adenovirus was determined. RESULTS: Of the 50 consecutive patients with acute infectious conjunctivitis, 31 patients were PCR positive for adenovirus. CONCLUSIONS: The prevalence of adenoviral conjunctivitis was found by PCR to represent 62% of all patients presenting with a clinical diagnosis of infectious conjunctivitis from July 2003 to October 2003.

The RPS adeno detector for diagnosing adenoviral conjunctivitis.

PURPOSE: To compare the sensitivity, specificity, and accuracy of the RPS Adeno Detector (Rapid Pathogen Screening Inc., South Williamsport, PA) against both viral cell culture with confirmatory immunofluorescence staining (CC-IFA) and the polymerase chain reaction (PCR) for diagnosing adenoviral conjunctivitis. DESIGN: Prospective, nonrandomized, masked, multicenter clinical trial. PARTICIPANTS: One hundred eighty-six consecutive patients from 5 clinical centers seeking treatment within 1 week of developing a red eye and thought to have acute conjunctivitis. METHODS: The RPS Adeno Detector is a 10-minute in-office lateral flow immunoassay. Patients were tested with the RPS Adeno Detector, CC-IFA, and PCR to detect the presence of adenovirus. MAIN OUTCOME MEASURES: The sensitivity, specificity, and accuracy of the RPS Adeno Detector were assessed for identifying cases of adenoviral conjunctivitis. RESULTS: Compared with CC-IFA, the RPS Adeno Detector was 88% sensitive and 91% specific at detecting adenoviral conjunctivitis. Using PCR as a reference method, the sensitivity of the RPS Adeno Detector increased to 89% and the specificity increased to 94%. Compared with PCR, CC-IFA was found to be 91% as sensitive and 100% as specific. CONCLUSIONS: The RPS Adeno Detector demonstrated sufficient sensitivity and specificity to be used in the physician's office for the detection of adenoviral conjunctivitis.

Measurement of scleral thickness in uveal effusion syndrome.

PURPOSE: To measure scleral thickness in patients with and without uveal effusion syndrome using ultrasound biomicroscopy (UBM) and magnetic resonance imaging (MRI). DESIGN: Prospective case-control study. METHODS: UBM was used to measure scleral thickness in five subjects with uveal effusion syndrome and five matched controls. We also used MRI to measure scleral thickness in three subjects. RESULTS: The mean thicknesses for eyes with uveal effusion syndrome versus control eyes were 0.65 +/- 0.08 mm and 0.55 +/- 0.05 mm, respectively (mean difference 0.10, P value = .13). MRI measurements of three subjects showed abnormally thick sclera but were imprecise. CONCLUSIONS: UBM can be used to measure scleral thickness, and our results support the finding that patients with uveal effusion syndrome have abnormally thick sclera. Compared with MRI, UBM may be a more accurate and precise method of measuring scleral thickness. UBM can be a useful adjunctive test in the management of uveal effusion syndrome.