Comparison of illumigene Group A Streptococcus Assay with Culture of Throat Swabs from Children with Sore Throats in the New Zealand School-Based Rheumatic Fever Prevention Program

Research opportunities for the primary prevention and management of acute rheumatic fever and rheumatic heart disease: a National Heart, Lung, and Blood Institute workshop report

Primary prevention of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) encompasses the timely diagnosis and adequate treatment of the superficial group A Streptococcus (GAS) infections pharyngitis and impetigo. GAS is the only known inciting agent in the pathophysiology of the disease. However, sufficient evidence indicates that the uptake and delivery of primary prevention approaches in RHD-endemic regions are significantly suboptimal. This report presents expert deliberations on priority research and implementation opportunities for primary prevention of ARF/RHD that were developed as part of a workshop convened by the US National Heart, Lung, and Blood Institute in November 2021. The opportunities identified by the Primary Prevention Working Group encompass epidemiological, laboratory, clinical, implementation and dissemination research domains and are anchored on five pillars including: (A) to gain a better understanding of superficial GAS infection epidemiology to guide programmes and policies; (B) to improve diagnosis of superficial GAS infections in RHD endemic settings; (C) to develop scalable and sustainable models for delivery of primary prevention; (D) to understand potential downstream effects of the scale-up of primary prevention and (E) to develop and conduct economic evaluations of primary prevention strategies in RHD endemic settings. In view of the multisectoral stakeholders in primary prevention strategies, we emphasise the need for community co-design and government engagement, especially in the implementation and dissemination research arena. We present these opportunities as a reference point for research organisations and sponsors who aim to contribute to the increasing momentum towards the global control and prevention of RHD.

Diagnosis and management of acute pharyngotonsillitis among pediatric patients at Ribat Teaching Hospital: a prospective audit (2021-2022)

Diagnosis of pharyngotonsillitis is challenging due to the wide range of symptoms and signs. Sudan Federal Ministry of Health and Sudanese Association of Paediatricians, along with Sudan Heart Society reached a consensus about the clinical prediction rule which aids in diagnosing and managing bacterial pharyngotonsillitis. This audit aimed to assess doctors' knowledge and practice regarding diagnosis and management of bacterial pharyngotonsillitis at Ribat Teaching Hospital, Khartoum, Sudan. This audit was done at Pediatric Department, Ribat Teaching Hospital, and data collection was done over 2 weeks either in the first or the second cycle. Inclusion criteria were children who presented at the emergency room and were diagnosed with acute pharyngotonsillitis. The criteria used in this audit were from Sudan guidelines for prevention, diagnosis and management of rheumatic heart disease. Regular training sessions were done between the first and second cycles. There were 19 patients in the first cycle, 17 of them (89.4%) were diagnosed clinically with bacterial pharyngotonsillitis, and 8 of these 17 (47%) were fitting the criteria. Regarding the management of bacterial pharyngotonsillitis, no patient was given the recommended antibiotics in the guidelines (0.00%). In the second cycle, there were 21 patients, of whom 11 patients were diagnosed clinically with bacterial pharyngotonsillitis (52%). Of those 11, 8 patients were fitting the criteria (72.7%), and the recommended antibiotics were given in 9 of them (82%). The current practice toward acute pharyngotonsillitis management revealed a lack of doctors' knowledge about local guidelines which can be improved by simple ways such as posters, lectures, and focused group discussions.

The Utility of Rapid Group A Streptococcus Molecular Testing Compared with Throat Culture for the Diagnosis of Group A Streptococcal Pharyngitis in a High-Incidence Rheumatic Fever Population

Group A streptococcus (GAS) causes significant morbidity and mortality in New Zealand and is responsible for invasive disease and immune sequelae, including acute rheumatic fever (ARF). Early treatment of GAS pharyngitis reduces the risk of ARF. In settings with a high burden of GAS disease, a rapid GAS pharyngitis diagnostic test with a strong negative predictive value is needed to enable prompt and accurate treatment. This prospective study compares the Xpert Xpress Strep A molecular test (Cepheid) to throat culture and a second molecular method, the BioGX group A streptococcus-open system reagent (OSR) for BD Max for the diagnosis of GAS pharyngitis. Throat swabs were collected from the emergency department and wards of Middlemore Hospital, New Zealand. The BioGX group A streptococcus OSR for BD Max contributes to the composite gold standard of throat culture or both molecular methods positive. Basic demographic, clinical, and laboratory data were collected. Two hundred five out of two hundred fourteen swabs were suitable for analysis. Of those, 28/205 (13.7%) were GAS culture positive, 45/205 (22%) Xpert Xpress Strep A positive, and 38/205 (18.5%) BioGX positive. Compared to culture, the sensitivity, specificity, and positive and negative predictive values of the Xpert Xpress Strep A molecular test were 100%, 90.4%, 62.2%, and 100%, respectively. Compared to the composite gold standard, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100%, 95.8%, 84.4%, and 100%, respectively. Seventeen samples were Xpert Xpress positive but culture negative; 6 of these 17 swabs represent true positives with evidence of recent GAS infection. Ten samples were culture negative but both Xpert Xpress and BioGX positive. The Xpert Xpress Strep A molecular test is highly sensitive with a strong negative predictive value and rapid turnaround time. It can be safely introduced as a first-line test for throat swabs in a high-incidence ARF population.

Here to stay: rapid nucleic acid tests for group A streptococcus pharyngitis

Dubois et al. report results of a meta-analysis assessing the diagnostic accuracy of rapid nucleic acid tests (RNATs) for group A Streptococcus (GAS) pharyngitis. While the accuracy of any diagnostic assay is crucial, the clinical application of these tests must be considered as these molecular assays become more widely implemented. We provide commentary to highlight the considerations for optimal use of RNATs in practice, taking into account the appropriate clinical context and setting to perform and evaluate these tests. Specifically, we address the critical clinical questions: "What is the benefit of rapid testing for GAS?" and "Under what circumstances should RNATs for GAS be utilized?"

Structured review of primary interventions to reduce group A streptococcal infections, acute rheumatic fever and rheumatic heart disease

Rheumatic heart disease (RHD) is a large, preventable, global public health burden. In New Zealand (NZ), acute rheumatic fever (ARF) and RHD rates are highest for Māori and Pacific children. This structured review explores the evidence for primary prevention interventions to diagnose and effectively treat group A Streptococcus (GAS) pharyngitis and skin infections to reduce rates of ARF and RHD. Medline, EMBASE and Scopus databases were searched as well as other electronic publications. Included were 50 publications from 1980 onwards. This review has identified that there is little available evidence for effective primary prevention strategies to reduce ARF rates in NZ. However, two primary intervention strategies that should be considered by communities at high-risk of ARF are: the use of school-based clinics to identify and treat GAS pharyngitis and GAS skin infections; and intramuscular benzathine penicillin G with lignocaine analgesia in children who present with a GAS positive throat.

Diagnostic accuracy of rapid nucleic acid tests for group A streptococcal pharyngitis: systematic review and meta-analysis

BACKGROUND

Acute pharyngitis is one of the most common conditions in outpatient settings and an important source of inappropriate antibiotic prescribing. Rapid antigen detection tests (RADTs) offer diagnosis of group A streptococcus at the point of care but have limited sensitivity. Rapid nucleic acid tests (RNATs) are now available; a systematic review of their accuracy is lacking.

OBJECTIVES

To evaluate the accuracy of RNATs in patients with pharyngitis; to explore test-level and study-level factors that could explain variability in accuracy; and to compare the accuracy of RNATs with that of RADTs.

DATA SOURCES

MEDLINE, Embase, Web of Science (1990-2020).

STUDY ELIGIBILITY CRITERIA

Cross-sectional studies and randomized trials.

PARTICIPANTS

Patients with pharyngitis.

INDEX TEST/S AND REFERENCE STANDARDS

RNAT commercial kits compared with throat culture.

METHODS

We assessed risk of bias and applicability using QUADAS-2. We performed meta-analysis of sensitivity and specificity using the bivariate random-effects model. Variability was explored by subgroup analyses and meta-regression.

RESULTS

We included 38 studies (46 test evaluations; 17 411 test results). RNATs were most often performed in a laboratory. The overall methodological quality of primary studies was uncertain because of incomplete reporting. RNATs had a summary sensitivity of 97.5% (95% CI 96.2%-98.3%) and a summary specificity of 95.1% (95% CI 93.6%-96.3%). There was low variability in estimates across studies. Variability in sensitivity and specificity was partially explained by test type (p < 0.05 for both). Sensitivity analyses limited to studies with low risk of bias showed robust accuracy estimates. RNATs were more sensitive than RADTs (13 studies; 96.8% versus 82.3%, p 0.004); there was no difference in specificity (p 0.92).

CONCLUSIONS

The high diagnostic accuracy of RNATs may allow their use as stand-alone tests to diagnose group A streptococcus pharyngitis. Based on direct comparisons, RNATs have greater sensitivity than RADTs and equal specificity. Further studies should evaluate RNATs in point-of-care settings.

Highly Sensitive Molecular Assay for Group A Streptococci Over-identifies Carriers and May Impact Outpatient Antimicrobial Stewardship

BACKGROUND

Timely, accurate diagnosis of group A streptococci (GAS) pharyngitis prevents acute rheumatic fever and limits antibiotic overuse. The illumigene group A Streptococcus assay (Meridian Bioscience, Cincinnati, OH) is a molecular test for GAS pharyngitis with high sensitivity and specificity. We sought to determine whether the illumigene test is more likely than throat culture to be positive in patients without pharyngeal symptoms and explore the limits of detection of the test.

METHODS

Patients 3-17 years of age were eligible if they had no history of pharyngitis or use of antibiotics within the previous 2 weeks; there were no upper respiratory infection symptoms, sore throat or fever and no signs of infection. Culture and illumigene were performed on duplicate throat swabs. Excess lysate from a subset of illumigene tests was evaluated by real-time polymerase chain reaction. Institutional Review Board approval was obtained.

RESULTS

We enrolled 385 patients from February 2016 to October 2017; mean age was 10 yr; 51% were male. Most visits were for health supervision (69%). Significantly more illumigene tests (78/385, 20.3%) than throat cultures (48/385, 12.5%) were positive (χ; P =0.0035). Illumigene was "indeterminate" for 3 patients, leaving 382 pairs of swabs for analysis. Results were discordant for 32 of 382 pairs (8.4%); 31 of 32 (97%) were illumigene-positive/culture-negative (McNemar test; P < 0.000001). Real-time polymerase chain reaction was negative in 4 of 13 (31%) tested illumigene-positive lysates; the paired culture had been negative in all four. The limit of detection for the illumigene test was 55 colony forming units/mL.

CONCLUSIONS

The illumigene test is significantly more likely than throat culture to yield positive results in patients without GAS pharyngitis. Failure to appropriately select patients for testing may negatively impact antimicrobial stewardship efforts without benefit to patients.

Multicenter Clinical Evaluation of the Automated Aries Group A Strep PCR Assay from Throat Swabs

Group A Streptococcus (GAS) is one of the leading causes of bacterial pharyngitis. Early GAS diagnosis is critical for appropriate antibiotic administration that reduces the risk of GAS sequelae and limits spread of the infection. The Aries Group A Strep (GAS) assay (Luminex, Austin, TX) is a fully automated PCR assay for direct detection of GAS in throat swab specimens in less than 2 h with minimum hands-on time. This multicenter prospective study evaluated the clinical performance of the Aries GAS assay compared to that of Streptococcus pyogenes culture. Subjects with symptoms consistent with pharyngitis were enrolled across four sites in the United States, and a throat swab in liquid Amies medium was obtained. Aries and reference testing was performed within 72 and 48 h after sample collection, respectively. Of 623 throat swab specimens from patients with pharyngitis (93.6% <18 years old, 54.3% female), the reference method yielded valid results for 618 specimens. Reference and Aries assay testing showed GAS-positive results for 160 (25.9%) and 166 (26.9%) specimens, respectively. Compared to the reference method, Aries assay sensitivity was 97.5% (95% confidence interval [CI], 93.7% to 99.0%), specificity was 97.8% (95% CI, 96.0 to 98.8%), positive predictive value was 94.0% (95% CI, 89.3% to 96.7%), and negative predictive value was 99.1% (95% CI, 97.7% to 99.7%). There were 10 false-positive and four false-negative detections with the Aries assay. Discrepant analysis with bidirectional sequencing yielded concordant results with the Aries assay for nine of 14 discordant samples. The Aries assay had high sensitivity and specificity for qualitative detection of group A Streptococcus from patients with pharyngitis.

Statistical Considerations for Bias and Protocol Deviation in Medical Device Pivotal Clinical Study

BACKGROUND

The gold standard in conducting clinical trials/studies is to follow what is prespecified in the study protocol. However, deviations from the study protocol may occur. This article discusses the issues of protocol deviation in pivotal clinical trials or studies for medical device and provides statistical approaches to mitigating bias such as selection bias specifically for diagnostic test clinical trials or studies.

METHOD

Bias correction methods are developed for 2 specific types of selection biases, prescreening bias and verification bias. Statistical approaches are discussed on how to estimate device performance adjusted for enrollment enrichment and discrepant testing results. We use an FDA-approved Roche Cobas Human Papillomavirus (HPV) test for detecting high-grade cervical disease (>CIN2) as an example to illustrate how to correct for verification bias. A recently FDA-cleared Microarray Assay in detecting copy number variation is used to illustrate how to properly estimate sensitivity and specificity for the discrepancy analysis.

RESULTS

The unadjusted sensitivity and specificity based on verified samples were 83.2% and 60.4% for the Roche's HPV test. However, using the correction method with the missing-at-random assumption, the verification bias-adjusted sensitivity and specificity were 34.5% and 93.6%, respectively.

CONCLUSION

Protocol deviations can lead to biased estimates of device clinical performance if not handled appropriately. Statistical methods correcting for bias and protocol deviations are recommended in estimating device performance.

Clinical Screening Tools to Diagnose Group A Streptococcal Pharyngotonsillitis in Primary Care Clinics to Improve Prescribing Habits

This review highlights the clinical scoring tools used for the management of acute pharyngotonsillitis in primary care clinics. It will include the prevalence of group A pharyngotonsillitis among children and adults worldwide and the selective tests employed for diagnosing group A streptococcal pharyngotonsillitis. Pharyngotonsillitis is one of the common reasons for visits to primary care clinics worldwide, and physicians tend to prescribe antibiotics according to the clinical symptoms, which leads to overprescribing antibiotics. This in turn may lead to serious health impacts and severe reactions and may promote antibiotic resistance. These significantly add on to the health care costs. The available information from health organisations and previous studies has indicated the need to manage the diagnosis of pharyngotonsillitis to improve prescribing habits in primary care clinics.

Prospective Postimplementation Study of Solana Group A Streptococcal Nucleic Acid Amplification Test vs Conventional Throat Culture

OBJECTIVES

We evaluated the Solana Group A Streptococcus Assay (Quidel, San Diego, CA), a nucleic acid amplification test (NAAT), as a substitute for backup culture on throat specimens with a negative rapid group A Streptococcus (GAS) antigen assay.

METHODS

During October 2016, all throat swabs from patients with a negative GAS antigen assay from local urgent care centers were processed by NAAT and conventional culture in real time.

RESULTS

The overall agreement of the 2,090 tested throat swab specimens of the NAAT with the culture was 2,050 (98%) of 2,090. Sensitivity, specificity, positive predictive value, and negative predictive value were 91.4%, 98.5%, 78.0%, and 99.5%, respectively.

CONCLUSIONS

In summary, this postimplementation study supported high sensitivity and specificity of the GAS NAAT as a backup test for negative rapid GAS antigen tests.