Performance of a rapid antigen-detection test and throat culture in community pediatric offices: implications for management of pharyngitis

Group A Streptococcus pharyngitis in Children: New Perspectives on Rapid Diagnostic Testing and Antimicrobial Stewardship

The most common cause of bacterial pharyngitis is Group A Streptococcus (GAS). Accurate diagnosis of GAS pharyngitis is crucial to identify children who would benefit from antibiotic treatment. Rapid diagnosis has the potential to reduce antibiotic overuse. Current national guidelines differ in their recommendations for GAS testing. While rapid antigen detection tests (RADTs) are widely used, their sensitivity is considered too low for stand-alone testing by several expert bodies. Newer molecular tests using nucleic acid amplification show higher accuracy and fast results, but their cost, complexity, and very high sensitivity may limit widespread adoption. This review provides up-to-date evidence regarding rapid diagnostic testing and antimicrobial stewardship in children with sore throat. We discuss discrepancies across GAS testing guidelines at the international level, patient selection for testing for GAS, rapid test accuracy, and the potential role of rapid GAS tests to promote antibiotic stewardship, with emphasis on emerging rapid molecular tests.

Development of a multiple cross displacement amplification combined with nanoparticles-based biosensor assay for rapid and sensitive detection of Streptococcus pyogenes

BACKGROUND

S. pyogenes, is a primary pathogen that leads to pharyngitis and can also trigger severe conditions like necrotizing fasciitis and streptococcal toxic shock syndrome (STSS), often resulting in high mortality rates. Therefore, prompt identification and appropriate treatment of S. pyogenes infections are crucial in preventing the worsening of symptoms and alleviating the disease's impact.

RESULTS

In this study, a newly developed technique called multiple cross displacement amplification (MCDA) was employed to detect S. pyogenes,specifically targeting the speB gene, at a temperature of 63°C within 30 min. Then, an easily portable and user-friendly nanoparticles-based lateral flow biosensor (LFB) assay was introduced for the rapid analysis of MCDA products in just 2 min. The results indicated that the LFB offers greater objectivity compared to Malachite Green and is simpler than electrophoresis. The MCDA-LFB assay boasts a low detection limit of 200 fg and exhibits no cross-reaction with non-S. pyogenes strains. Among 230 clinical swab throat samples, the MCDA-LFB method identified 27 specimens as positive, demonstrating higher sensitivity compared to 23 samples detected positive by qPCR assay and 18 samples by culture. The only equipment needed for this assay is a portable dry block heater. Moreover, each MCDA-LFB test is cost-effective, priced at approximately $US 5.5.

CONCLUSION

The MCDA-LFB assay emerges as a straightforward, specific, sensitive, portable, and user-friendly method for the rapid diagnosis of S. pyogenes in clinical samples.

Diagnostic performance of clinical prediction rules to detect group A beta-haemolytic streptococci in people with acute pharyngitis: a systematic review

OBJECTIVE

To assess and compare the diagnostic performance of Clinical Prediction Rules (CPRs) developed to detect group A Beta-haemolytic streptococci in people with acute pharyngitis (or sore throat).

STUDY DESIGN

A systematic review.

METHODS

We searched PubMed, Embase and Web of Science (inception-September 2022) for studies deriving and/or validating CPRs comprised of ≥2 predictors from an individual's history or physical examination. Two authors independently screened articles, extracted data and assessed risk of bias in included studies. A meta-analysis was not possible due to heterogeneity. Instead we compared the performance of CPRs when they were validated in the same study population (head-to-head comparisons). We used a modified grading of recommendations, assessment, development, and evaluations (GRADE) approach to assess certainty of the evidence.

RESULTS

We included 63 studies, all judged at high risk of bias. Of 24 derived CPRs, 7 were externally validated (in 46 external validations). Five validation studies provided data for head-to-head comparison of four pairs of CPRs. Very low certainty evidence favoured the Centor CPR over the McIsaac (2 studies) and FeverPain CPRs (1 study) and found the Centor CPR was equivalent to the Walsh CPR (1 study). The AbuReesh and Steinhoff 2005 CPRs had a similar poor discriminative ability (1 study). Within and between study comparisons suggested the performance of the Centor CPR may be better in adults (>18 years).

CONCLUSION

Very low certainty evidence suggests a better performance of the Centor CPR. When deciding about antibiotic prescribing for pharyngitis patients, involving patients in a shared decision making discussion about the likely benefits and harms, including antibiotic resistance, is recommended. Further research of higher rigour, which compares CPRs across multiple settings, is needed.

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.

Diagnostic accuracy of a rapid nucleic acid test for group A streptococcal pharyngitis using saliva samples: protocol for a prospective multicenter study in primary care

BACKGROUND

Group A streptococcus is found in 20-40% of cases of childhood pharyngitis; the remaining cases are viral. Streptococcal pharyngitis ("strep throat") is usually treated with antibiotics, while these are not indicated in viral cases. Most guidelines recommend relying on a diagnostic test confirming the presence of group A streptococcus before prescribing antibiotics. Conventional first-line tests are rapid antigen detection tests based on throat swabs. Recently, rapid nucleic acid tests were developed; they allow the detection of elements of the genome of group A streptococcus. We hypothesize that these rapid nucleic acid tests are sensitive enough to be performed on saliva samples instead of throat swabs, which could be more convenient in practice.

METHODS

This is a multicenter, prospective diagnostic accuracy study evaluating the performance of a rapid nucleic acid test for group A streptococcus (Abbott ID NOW STREP A2) in saliva, compared with a conventional pharyngeal rapid antigen detection test (EXACTO PRO STREPTATEST, lateral flow assay, comparator test), with a composite reference standard of throat culture and group A streptococcus PCR in children with pharyngitis in primary care (i.e., 27 primary care pediatricians or general practitioners). To ensure group A streptococcus is not missed, the salivary rapid nucleic acid test requires a minimally acceptable value of sensitivity (primary outcome) set at 80%. Assuming 35% of participants will have group A streptococcus, we will recruit 800 consecutive children with pharyngitis. Secondary outcomes will include difference in sensitivity between the pharyngeal rapid antigen detection test and the salivary rapid nucleic acid test; variability in sensitivity and specificity of the salivary rapid nucleic acid test with the level of McIsaac score; time to obtain the result of the salivary rapid nucleic acid test; patient, physician, and parents satisfaction; and barriers and facilitators to using rapid tests for group A streptococcus in primary care.

ETHICS AND DISSEMINATION

Approved by the Institutional Review Board "Comité de protection des personnes Ile de France I" (no. 2022-A00085-38). Results will be presented at international meetings and disseminated in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT05521568.

Performance of a Molecular Test for Group A Streptococcus Pharyngitis

We performed a prospective study to determine if the pretest probability of a positive loop-mediated isothermal amplification test is greater when there are more signs and symptoms of GAS pharyngitis. Patients were enrolled if a clinician obtained a GAS RADT. The McIsaac score was calculated. The prevalence of positive LAMP and RADT results increased as the McIsaac score increased. The calculated sensitivity of LAMP was superior to RADT.

Inappropriate Testing of Streptococcal Pharyngitis in Children Aged Below 3 Years: Application of Statistical Process Control

Group A strep tests in patients aged below 3 years are not recommended unless the patient has appropriate symptoms and a positive contact or signs of complications. The purpose of this quality improvement project was to increase the percentage of appropriately ordered strep tests among providers. Data were collected retrospectively and prospectively from 1163 patient visits. Providers were exposed to educational interventions, an electronic medical record order change, and provider feedback. Proportional control charts characterized the providers' behaviors and determined significant improvement among testing. The result was an increase in appropriate tests (13.7% to 37.8%), and the control charts showed sustainable results over time. This project demonstrates the efficacy of these methods to encourage antibiotic stewardship among providers. Furthermore, the interventions used here can be applied to other areas with low-value diagnostic testing. Future studies should investigate whether parental anxiety and educational programs influence testing and evaluate the efficacy of certain strategies.

Standardization of Epidemiological Surveillance of Group A Streptococcal Pharyngitis

Pharyngitis, more commonly known as sore throat, is caused by viral and/or bacterial infections. Group A Streptococcus (Strep A) is the most common bacterial cause of pharyngitis. Strep A pharyngitis is an acute, self-limiting disease but if undertreated can lead to suppurative complications, nonsuppurative poststreptococcal immune-mediated diseases, and toxigenic presentations. We present a standardized surveillance protocol, including case definitions for pharyngitis and Strep A pharyngitis, as well as case classifications that can be used to differentiate between suspected, probable, and confirmed cases. We discuss the current tests used to detect Strep A among persons with pharyngitis, including throat culture and point-of-care tests. The type of surveillance methodology depends on the resources available and the objectives of surveillance. Active surveillance and laboratory confirmation is the preferred method for case detection. Participant eligibility, the surveillance population and additional considerations for surveillance of pharyngitis are addressed, including baseline sampling, community engagement, frequency of screening and season. Finally, we discuss the core elements of case report forms for pharyngitis and provide guidance for the recording of severity and pain associated with the course of an episode.

Group A Streptococcal Pharyngitis Testing Appropriateness in Pediatric Acute Care Settings

OBJECTIVE

Acute pharyngitis is one of the most common causes of ambulatory clinic visits; however, group A Streptococcus accounts for less than a third. National guidelines recommend against streptococcal testing in patients with viral features. This study aims to assess the rate of inappropriate streptococcal rapid antigen detection tests (RADT)s in children evaluated in urgent care clinics (UCC)s and emergency department (ED)s at a children's hospital.

METHODS

We retrospectively reviewed charts of 10% of children 3 years or older with RADTs ordered between April and September 2018 at EDs and UCCs. The test was determined to be inappropriate if the patient had no sore throat and/or had 2 or more viral symptoms: rhinorrhea/congestion, cough, diarrhea, hoarseness, conjunctivitis, or viral exanthem.

RESULTS

Over the study period, 7678 RADTs were performed, of which 7024 (91.2%) were in children 3 years or older. We evaluated 708 charts and found 44% of RADTs were inappropriate. The predicted probability of inappropriate RADT was highest among patients with a triaged reason for visit for respiratory complaints (70.5%), viral upper respiratory tract infection (69.7%), and rash (61.3%). Of the inappropriate RADTs, 20.1% were positive, whereas 32.2% of the appropriate RADTs were positive.

CONCLUSION

Quality improvement initiatives are needed to decrease the rate of inappropriate RADTs in pediatric UCC and ED settings.

The treatment of streptococcal tonsillitis/pharyngitis in young children

Pharyngitis is common in children, accounting for nearly 12 million visits annually in the United States. Streptococcus pyogenes or group A streptococcus (GAS) is the most common bacterial cause of pharyngitis for which antibiotics are indicated. Antibiotic treatment of streptococcal pharyngitis virtually eliminates the presence of bacteria from the pharynx and thus removes the risk of subsequent rheumatic fever. GAS is spread from person to person via respiratory droplets with a short incubation period of 2∼5 days. GAS pharyngitis peaks in the late winter and early spring months when children are predominately indoors for school and sports. Colonization is also higher in winter months, and while up to 20% of school age children are colonized with GAS in their throat during this time, colonization has not been shown to contribute to the spread of disease. In low- and middle-income countries and other situations in which crowding is common (e.g., schools), outbreaks of pharyngitis are common. GAS pharyngitis can occur at all ages and it is most common in school-aged children with a peak at 7∼8 years of age. Pharyngitis caused by GAS is rare in children <3 years of age and becomes much less common in late adolescence through adulthood.

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?"

A Comparison of Diagnostic Accuracy of a Rapid Antigen Detection Test in Screening for Group A Streptococcal Throat Infection Between 3- to 10-Year-Old (Children and Preadolescents) and 11- to 21-Year-Old (Adolescents)

Introduction

Pharyngitis is one of the most common childhood diseases worldwide. We intended to compare the performance of one such rapid antigen detection test (RADT) using lateral flow immunoassay technique, between 3- to 10-year-old (children and preadolescent) and 11- to 21-year-old (adolescents).

Methods

Children and adolescents attending the pediatric ED with complaints of throat pain and signs of pharyngeal and tonsillar inflammation were tested by both the RADT and throat culture (TC) directed towards group A streptococcal (GAS) between April and June of 2016. The prevalence, sensitivity (SN), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV) were calculated against throat culture, the gold standard for the diagnosis of GAS pharyngitis. Comparisons between the two age groups were made using the Chi-square test

Results

Of 202 patients, 123 (61%) patients were between 3-11 and 79 (39%) between 11-21 years of age. A positive throat culture was recorded in 56 patients yielding an overall prevalence of GAS pharyngitis at 28%. For the whole sample, the screening RADT had an SN, SP, PPV and NPV of 79%, 90%, 75%, and 92%, respectively. Also, there was no statistically significant difference between the two groups in terms of SN, SP, PPV and NPV.

Conclusion

The RADT in use at our institution, performed comparable to studies reported in the literature using a similar technique in both preadolescent and adolescent age groups.

Rapid Antigen Detection Test Using Rates of Family Physicians, Test Results and Its Impact on Their Prescription Behaviours

Aim: The aim of this study is to determine the rates of rapid antigen detection test use, test results and its relationship with Modified Centor Score and investigate the effect of rapid antigen detection test use on prescribing behaviour. Methods: This research was conducted by scanning the family physicians’ information system retrospectively. From the Family Medicine Information System, where polyclinics and prescription records of the family health centers where 12 family physicians work in Kayseri are located, the number and results of rapid antigen detection tests performed between February 2017 and April 2019, the Modified Centor Score automatically calculated by the system, the number of prescribed antibiotics and symptomatic treatment information was recorded. Results: The positivity of rapid antigen detection test was considered, cut-off value of Modified Centor Score was >2 (ROC EAA:63.9, Cl:0.95,0.61-0.66). Sensitivity rate of the test for diagnostic score was 86% and selectivity rate was 48.8%. Conclusion: Family physicians should be encouraged to use rapid antigen detection test. The fact that antibiotics are prescribed in rapid antigen detection testnegative patients may indicate that confidence level of the test is less than physical examination and clinical findings. Keywords: sore throat, primary care, score

Diagnostic Methods, Clinical Guidelines, and Antibiotic Treatment for Group A Streptococcal Pharyngitis: A Narrative Review

The most common bacterial cause of pharyngitis is infection by Group A β-hemolytic streptococcus (GABHS), commonly known as strep throat. 5-15% of adults and 15-35% of children in the United States with pharyngitis have a GABHS infection. The symptoms of GABHS overlap with non-GABHS and viral causes of acute pharyngitis, complicating the problem of diagnosis. A careful physical examination and patient history is the starting point for diagnosing GABHS. After a physical examination and patient history is completed, five types of diagnostic methods can be used to ascertain the presence of a GABHS infection: clinical scoring systems, rapid antigen detection tests, throat culture, nucleic acid amplification tests, and machine learning and artificial intelligence. Clinical guidelines developed by professional associations can help medical professionals choose among available techniques to diagnose strep throat. However, guidelines for diagnosing GABHS created by the American and European professional associations vary significantly, and there is substantial evidence that most physicians do not follow any published guidelines. Treatment for GABHS using analgesics, antipyretics, and antibiotics seeks to provide symptom relief, shorten the duration of illness, prevent nonsuppurative and suppurative complications, and decrease the risk of contagion, while minimizing the unnecessary use of antibiotics. There is broad agreement that antibiotics with narrow spectrums of activity are appropriate for treating strep throat. But whether and when patients should be treated with antibiotics for GABHS remains a controversial question. There is no clearly superior management strategy for strep throat, as significant controversy exists regarding the best methods to diagnose GABHS and under what conditions antibiotics should be prescribed.

The antibiotic prescribing behaviors of physicians are changed via rapid antigen test practice in the context of rational drug use

Background/aim

Rapid antigen test (RAT) is a practical test to detect the presence of Group A beta hemolytic streptococcus antigens in throat swab samples. The aim of this study is to investigate the changes in the empiric antibiotic prescribing behavior of 10 family physicians in Kırıkkale Province after using RAT in 2017.

Materials and methods

RAT test practice started in Family Medicine in February 2017. Family Medicine Information System (FMIS) includes clinical and prescription records of 10 family physicians, providing health service to approximately 35,000 residents in Kırıkkale. The numbers of antibiotics prescribed by the physicians according to the ICD-10 codes (including upper respiratory tract infections) in February, March, and April of 2015, 2016, 2017 were determined. The number and group of antibiotics prescribed by the family physicians with the determined diagnosis and time periods were specified in the FMIS and recorded.

Results

Antibiotic prescription behaviors of family physicians do not show a significant difference between 2015 and 2016. There was a dramatic and significant decrease in the number of prescribed antibiotics in 2017 compared to 2015 and 2016 (P < 0.05).

Conclusion

This study shows that there has been a significant decrease in antibiotic prescription in 10 Family Medicine departments in 2017 in comparison to February, March, and April 2015 and 2016. The use of RAT resulted in a decrease in antibiotic prescription rates in 2017.

Efficacy and safety of rapid tests to guide antibiotic prescriptions for sore throat

BACKGROUND

Sore throat is a common condition caused by viruses or bacteria, and is a leading cause of antibiotic prescription in primary care. The most common bacterial species is group A streptococcus ('strep throat'). Between 50% to 70% of pharyngitis cases are treated with antibiotics, despite the majority of cases being viral in origin. One strategy to reduce antibiotics is to use rapid tests for group A streptococcus to guide antibiotic prescriptions. Rapid tests can be used alone or in combination with a clinical scoring system.

OBJECTIVES

To assess the efficacy and safety of strategies based on rapid tests to guide antibiotic prescriptions for sore throat in primary care settings.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, Web of Science, and LILACS, as well as the trial registries ClinicalTrials.gov and the WHO ICTRP on 5 June 2019.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing rapid tests with management based on clinical grounds to guide the prescription of antibiotics for people with a sore throat in ambulatory care settings. We included trials that randomised individuals, as well as cluster-RCTs in which individual practitioners (or practices) or emergency departments were randomised.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data on the primary outcomes (number of participants provided with an antibiotic prescription; number of participants with an antibiotic dispensed) and secondary outcomes (duration of sore throat symptoms; duration of other symptoms; quality of life measures; number of participants with a complication attributed to the index infection; number of participants in need of re-consultation by the end of follow-up; number of participants in need of hospital admission by the end of follow-up; number of satisfied participants; number of participants with an adverse event attributed to the rapid test). We assessed the risk of bias of all included trials and used GRADE to assess the certainty of the evidence. We performed meta-analyses and sensitivity analyses when feasible.

MAIN RESULTS

We included five trials (2891 children and adult participants in total; 2545 participants after adjusting for clustering). Management in the intervention group was as follows: in three trials rapid tests were used in combination with a clinical scoring system; in one trial, some physicians were asked to use rapid tests alone, while others were asked to use rapid tests in combination with a clinical scoring system; in one trial, rapid tests were used alone. Based on data from five trials (2545 participants), a large reduction in prescribed antibiotics was found in the rapid test group (481/1197) versus management based on clinical grounds (865/1348), for a summary risk difference (RD) of -25%, 95% confidence interval (CI) -31% to -18%; I² = 62%; moderate-certainty evidence. Estimates of effect on antibiotic prescription rates were stable in various sensitivity analyses. Based on data from two trials (900 people) originating from the same overarching study, the evidence suggests that rapid tests may not reduce dispensed antibiotic treatments: rapid test group (156/445) versus management based on clinical grounds (197/455); summary RD -7%, 95% CI -17% to 2%; I² = 53%; low-certainty evidence. Four trials (2075 participants) reported data on the number of participants with a complication attributed to the index infection; the summary odds ratio (OR) was 0.85, 95% CI 0.03 to 26.65; P = 0.93; I² = 62%; very low-certainty evidence, which means that people in the rapid testing group were less likely to develop complications of the index infection, but the evidence is very uncertain. Two trials (1161 participants) reported on the number of participants in need of re-consultation by the end of follow-up; the summary OR was 1.12, 95% CI 0.57 to 2.21; P = 0.74; I² = 59%; low-certainty evidence, which means that participants in the rapid testing group were more likely to be in need of re-consultation by the end of the study follow-up, but the evidence is uncertain. Lack of data impeded assessment of other secondary outcomes (including safety outcomes) and of sources of heterogeneity.  AUTHORS' CONCLUSIONS: Rapid testing to guide antibiotic treatment for sore throat in primary care probably reduces antibiotic prescription rates by 25% (absolute risk difference), but may have little or no impact on antibiotic dispensing. More studies are needed to assess the efficacy and safety of rapid test-guided antibiotic prescribing, notably to evaluate patient-centred outcomes and variability across subgroups (e.g. adults versus children).

The use of bacterial DNA from saliva for the detection of GAS pharyngitis

Background

Acute tonsillitis is a very common medical condition. Despite different methods of detection, all tests are based on GAS sampling using a throat swab. However, obtaining the swab can elicit vomiting and is often accompanied by fear and apprehension in children. The aim of this study was to find a non-invasive method for the detection of GAS pharyngitis.

Methods

A classic throat swab was obtained for culture, and a saliva sample was taken from 100 subjects recruited from Meuhedet Health Care Organization clinic. Real time PCR was performed to detect GAS dnaseB specific gene in the saliva samples.

Results

56% of the throat cultures and 48% of the PCR samples were positive for GAS. The overall sensitivity and specificity of the saliva PCR method was 79% and 91% respectively; NPV and PPV were 77% and 92% respectively. When excluding patients who presented on the first day of fever, sensitivity and specificity increased to 90% and 100% respectively. No other anamnestic or clinical findings increased the yield of the test.

Conclusion

Saliva-based PCR amplification of GAS DNA method is effective in detection of GAS pharyngitis. Further studies are needed to achieve detection rates to replace the traditional throat swab-based approach.

Identifying Patients at Lowest Risk for Streptococcal Pharyngitis: A National Validation Study

OBJECTIVES

To determine the prevalence of features of viral illness in a national sample of visits involving children tested for group A Streptococcus pharyngitis. Additionally, we sought to derive a decision rule to identify patients with features of viral illness who were at low risk of having group A Streptococcus and for whom laboratory testing might be avoided.

STUDY DESIGN

Retrospective validation study using data from electronic health records of patients 3-21 years old evaluated for sore throat in a national network of retail health clinics (n = 67 127). We determined the prevalence of features of viral illness in patients tested for group A Streptococcus and developed a decision tree algorithm to identify patients with features of viral illness at low risk (<15%) of having group A Streptococcus.

RESULTS

Overall, 54% of patients had features of viral illness. Among patients with features of viral illness, those without tonsillar exudates who were 11 years or older and either lacked cervical adenopathy or had cervical adenopathy and lacked fever were identified as at low risk for group A Streptococcus according to the decision rule. This group comprised 34% of patients with features of viral illness, or 19% of all patients tested for group A Streptococcus infection.

CONCLUSIONS

Our findings provide an objective way to identify patients with features of viral illness who are at low risk of having group A Streptococcus. Improved identification such patients at low risk of group A Streptococcus could improve appropriate testing and antibiotic prescribing for pharyngitis.

Comparison of Centor and McIsaac scores in primary care: a meta-analysis over multiple thresholds

Background

Centor and McIsaac scores are both used to diagnose group A beta-haemolytic streptococcus (GABHS) infection, but have not been compared through meta-analysis.

Aim

To compare the performance of Centor and McIsaac scores at diagnosing patients with GABHS presenting to primary care with pharyngitis.

Design and setting

A meta-analysis of diagnostic test accuracy studies conducted in primary care was performed using a novel model that incorporates data at multiple thresholds.

Method

MEDLINE, EMBASE, and PsycINFO were searched for studies published between January 1980 and February 2019. Included studies were: cross-sectional; recruited patients with sore throats from primary care; used the Centor or McIsaac score; had GABHS infection as the target diagnosis; used throat swab culture as the reference standard; and reported 2 × 2 tables across multiple thresholds. Selection and data extraction were conducted by two independent reviewers. QUADAS-2 was used to assess study quality. Summary receiver operating characteristic (SROC) curves were synthesised. Calibration curves were used to assess the transferability of results into practice.

Results

Ten studies using the Centor score and eight using the McIsaac score were included. The prevalence of GABHS ranged between 4% and 44%. The areas under the SROC curves for McIsaac and Centor scores were 0.7052 and 0.6888, respectively. The P-value for the difference (0.0164) was 0.419, suggesting the SROC curves for the tests are equivalent. Both scores demonstrated poor calibration.

Conclusion

Both Centor and McIsaac scores provide only fair discrimination of those with and without GABHS, and appear broadly equivalent in performance. The poor calibration for a positive test result suggests other point-of-care tests are required to rule in GABHS; however, with both Centor and McIsaac scores, a score of ≤0 may be sufficient to rule out infection.

Acute Otitis Media and Group A Streptococcal Pharyngitis: A Review for the General Pediatric Practitioner

For pediatric practitioners, acute otitis media (AOM) and group A streptococcal pharyngitis are two of the most common infections seen in ambulatory practices. The purpose of this article is to review these conditions with the focus of highlighting evidence-based guidelines. AOM in children is a visual diagnosis and not one that can be made on history alone. The American Academy of Pediatrics (AAP) guidelines have clear criteria to aid clinicians in how to diagnose AOM. The pneumatic otoscope is the standard tool used to diagnose otitis media, and the AAP guidelines stress developing proficiency in distinguishing a normal tympanic membrane from otitis media with effusion or AOM. There are several components to appropriate management (treatment) of AOM including analgesia, education, antibiotics, and the option (for some) for observation. Group A streptococcal pharyngitis is the most common bacterial cause of sore throat in children but still only accounts for a minority of cases. History and physical examination help determine who should be tested. Testing is required to determine who to treat. Up to 15% of children in the United States are carriers, so indiscriminate testing can lead to inappropriate antibiotic use. If a patient's test is positive, treatment is recommended and penicillin or amoxicillin are appropriate for most cases. [Pediatr Ann. 2019;48(9):e343-e348.].

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.

Detection of group a Streptococcus in pharyngitis by two rapid tests: comparison of the BD Veritor™ and the QuikRead go® Strep A

We compared the performance of two rapid antigen tests-QuikRead go® Strep A test (Orion Diagnostica, Espoo, Finland) and BD Veritor™ system (Becton, Dickinson and Company, Sparks, MD) with throat culture. Our aim was to evaluate each assay's performance and agreement compared to throat culture in order to choose one of the assays as a point-of-care test in the emergency room. One hundred throat samples were collected in triplicates from patients with suspected pharyngitis admitted to the emergency room. One throat swab was seeded for a throat culture. The other two throat swabs from each patient were analyzed at the emergency room by the QuikRead go® Strep A test, and by the BD Veritor™ system, according to each manufacturer's instructions. Agreement level between BD Veritor™ test and throat culture was 79%; sensitivity and specificity of this test were 80% and 78.7%, respectively. QuikRead go® Strep A test had an agreement level of 75% with throat culture; sensitivity and specificity of this test were 80% and 73.3%, respectively. Both tests have a good diagnostic performance. Other characteristics such as costs, size of instrument, and ease of implementation should be taken into consideration when choosing a point-of-care test.

Diagnosis and antibiotic treatment of group a streptococcal pharyngitis in children in a primary care setting: impact of point-of-care polymerase chain reaction

BACKGROUND

To compare the sensitivity and specificity of the recommended 2-step rapid antigen detection test (RADT) with confirmatory culture vs the point-of-care (POC) polymerase chain reaction (PCR) Roche cobas® Liat® Strep A test for detection of group A Streptococcus (GAS) in pediatric patients with pharyngitis, and to investigate the impact of these tests on antibiotic use in a large pediatric clinic.

METHODS

This prospective, open-label study was conducted at a single site during fall/winter 2016-2017. A total of 275 patients aged 3 to 18 years with symptoms of pharyngitis had a throat-swab specimen analyzed using RADT, POC PCR, and culture. The sensitivity, specificity, and percentage agreement (95% CI) between assays and a laboratory-based nucleic acid amplification test were calculated. DNA sequencing was used to adjudicate discrepancies. The RADT or POC PCR result was provided to clinicians on alternating weeks to compare the impact on antibiotic use.

RESULTS

A total of 255 samples were evaluated; 110 (43.1%) were GAS positive. Sensitivities (95% CI) for POC PCR, RADT, and culture were 95.5% (89.7-98.5%), 85.5% (77.5-1.5%), and 71.8% (62.4-80.0%), respectively. Specificities (95% CI) for POC PCR, RADT, and culture were 99.3% (96.2-99.98%), 93.7% (88.5-97.1%), and 100% (97.5-100%), respectively. Compared with RADT, POC PCR resulted in significantly greater appropriate antibiotic use (97.1% vs 87.5%; P = .0065).

CONCLUSION

Under real-world conditions, RADT results were less specific and culture results were less sensitive than found in established literature and led to increased rates of inappropriate antibiotic use. POC PCR had high sensitivity and specificity and rapid turnaround times, and led to more appropriate antibiotic use.

TRIAL REGISTRATION

ID number ISRCTN84562679 . Registered October 162,018, retrospectively registered.

Caution Needed: Molecular Diagnosis of Pediatric Group A Streptococcal Pharyngitis

Among throat swabs processed in the microbiology laboratory as back-up for negative rapid antigen detection test results, we found a significant increase in the proportion that tested positive for group A streptococci after changing from throat culture to a molecular test.For group A streptococcus testing, our hospital laboratory replaced throat cultures with a stand-alone molecular diagnostic test that takes no more than 1 hour to perform. The prevalence of positive laboratory test results increased significantly (P < .0001) after the change to molecular testing, probably because of the extreme sensitivity of the molecular test.

Molecular Detection of Streptococcus pyogenes by Strand Invasion Based Amplification Assay

Introduction

Streptococcus pyogenes (group A Streptococcus, GAS) is responsible for a variety of highly communicable infections, accounting for 5–15 and 20–30% of sore throat hospital visits in adults and children, respectively. Prompt diagnosis of GAS can improve the quality of patient care and minimize the unnecessary use of antibiotics.

Objective

Our objective was to develop an alternative nucleic acid amplification method for the diagnosis of GAS.

Method

We developed and evaluated a strand invasion based amplification (SIBA) assay to rapidly and specifically detect GAS. The performance of the developed GAS SIBA assay was compared with an established GAS polymerase chain reaction (PCR) assay.

Results

The GAS SIBA assay detected small amounts (ten copies) of S. pyogenes DNA within 13 min. The rapid detection time was achieved in part by optimization of magnesium concentration and reaction temperature. The sensitivity and specificity of the GAS SIBA assay for detection of S. pyogenes from clinical specimens were both 100%, and clinical specimens were detected within ~ 8 min of starting the reaction.

Conclusion

Because the GAS SIBA assay is performed at low and constant temperature, it can be used both in centralized laboratories and for point-of-care testing. Furthermore, given its short detection time and strong analytical performance, the GAS SIBA assay could help to improve patient care and minimize unnecessary prescription of antibiotics.

Signs and symptoms of Group A versus Non-Group A strep throat: A meta-analysis

INTRODUCTION

Both non-Group A streptococcal (non-GAS) pharyngitis and Group A streptococcal (GAS) pharyngitis are commonly found in patients with sore throat. It is not known whether or not they present with similar signs and symptoms compared to patients with non-streptococcal pharyngitis.

METHODS

MEDLINE was searched for prospective studies that reported throat culture for both GAS and non-GAS as a reference standard, and reported at least one sign, symptom, or the Centor score. Summary estimates of sensitivity, specificity, likelihood ratios (LR+ and LR-), and diagnostic odds ratios (DOR) were calculated using a bivariate random effects model. Summary receiver operating characteristic (ROC) curves were created for key signs and symptoms.

RESULTS

Eight studies met our inclusion criteria. Tonsillar exudate had the highest LR+ for both GAS and non-GAS pharyngitis (1.53 versus 1.71). The confidence intervals of sensitivity, LR+, LR-, and DOR for all signs, symptoms, and the Centor score between two groups overlapped, with the relative difference between sensitivities within 15% for arthralgia or myalgia, fever, injected throat, tonsillar enlargement, and tonsillar exudate. Larger differences in sensitivities were observed for sore throat, cervical adenopathy, and lack of a cough, although the difference for lack of a cough largely due to a single outlier.

DISCUSSION

Signs and symptoms of patients with GAS and non-GAS pharyngitis are generally similar. No signs or symptoms clearly distinguish GAS from non-GAS infection. Further work is needed to determine whether Group C streptococcus is a pathogen that should be treated.

Clinical Impact of a Rapid Streptococcal Antigen Test on Antibiotic Use in Adult Patients

INTRODUCTION

Adult pharyngitis is rarely attributable to group A streptococci. Utilization of a rapid streptococcal antigen test (RADT) may improve appropriate prescribing for bacterial pharyngitis.

METHODS

Clinic 1 performed RADTs with subsequent Group A DNA probe test (GADNA) from November 2014-March 2015 and November 2015-March 2016 while Clinic 2 was the control clinic, then implemented the RADT with a GADNA from November 2015-March 2016. All GADNA results were obtained for each clinic from October 2013-March 2016.

RESULTS

At Clinic 1, 22.2% versus 8.5% of patients received inappropriately prescribed antibiotics for a GADNA or RADT result, respectively (p=0.048). For Clinic 2, 51.1% compared to 21.4% of patients were inappropriately prescribed antibiotic for a GADNA or RADT result, respectively (p=0.038). Overall, the total GADNA without RADT testing or RADTs with subsequent GADNA testing, 41.6% versus 11% of patients were inappropriately prescribed antibiotics, respectively (p=<0.0001).

CONCLUSION

Utilizing the RADT prevented unnecessary prescribing of antibiotics in adults.

Reduction of antibiotic prescriptions for acute respiratory tract infections in primary care: a systematic review

BACKGROUND

Although most respiratory tract infections (RTIs) are due to viral infections, they cause the majority of antibiotic (Abx) prescriptions in primary care. This systematic review summarises the evidence on the effectiveness of interventions in primary care aiming to reduce Abx prescriptions in patients ≥ 13 years for acute RTI.

METHODS

We searched the databases "MEDLINE/PubMed" and "Cochrane Library" for the period from January 1, 2005, to August 31, 2016, for randomised controlled trials (RCTs) in primary care aiming at the reduction of Abx prescriptions for patients suffering from RTI. Out of 690 search results, 67 publications were retrieved and 17 RCTs were included. We assumed an absolute change of 10% as minimal important change.

RESULTS

Twelve out of 17 included RCTs showed statistically significant lower Abx prescription rates in the intervention groups, but only six of them reported a clinically relevant reduction according to our definition. Communication skills training (CST) and point-of-care testing (POCT) were the most effective interventions. Pre-intervention Abx prescription rates varied between 13.5% and 80% and observed reductions ranged from 1.5 to 23.3%. Studies with post-intervention rates lower than 20% had no significant effects. Post-intervention observation periods ranged from 2 weeks up to 3.5 years. The design of the trials was heterogeneous precluding calculation of pooled effect size. The reporting of many RCTs was poor.

CONCLUSIONS

CST and POCT alone or as adjunct can reduce antibiotic prescriptions for RTI. Eleven out of 17 trials were not successfully reducing Abx prescription rates according to our definition of minimal important change. However, five of them reported a statistically significant reduction. Trials with initially lower prescription rates were less likely to be successful. Future trials should investigate sustainability of intervention effects for a longer time period. The generalisability of findings was limited due to heterogeneous designs and outcome measures. Therefore, a consensus of designing and reporting of studies aiming at reducing antibiotic prescriptions is urgently needed to generate meaningful evidence.

Comparison of the Alere i Strep A Test and the BD Veritor System in the Detection of Group A Streptococcus and the Hypothetical Impact of Results on Antibiotic Utilization

Rapid detection of group A Streptococcus (GAS) is an integral component of treatment decisions in the clinic, especially in the pediatric population. We prospectively collected 216 specimens from symptomatic, predominantly pediatric patients and evaluated the performance of the Alere i Strep A test (Alere i; Alere Inc., Scarborough, ME) and the BD Veritor system (BD Veritor; Becton, Dickinson and Company, Sparks, MD), with culture results being used as a comparator. Real-time PCR (RT-PCR) was performed as an arbiter in discordant cases. Comprehensive chart review was also done to determine the hypothetical impact of the results on antibiotic use. Alere i had a sensitivity and a specificity of 100% and 91.3%, respectively, and BD Veritor had a sensitivity and a specificity of 76.2% and 93.6%, respectively, when the results were compared to those of GAS culture. Further analysis of discordant results using RT-PCR revealed that while BD Veritor missed 13 confirmed positive cases, Alere i detected 100% (n = 13) of the same cases. Analysis of assay agreement showed that Alere i and BD Veritor had only moderate agreement (agreement = 0.888 [95% confidence interval {CI}, 0.838 to 0.927]; kappa index = 0.689 [95% CI, 0.91 to 0.974]). We also found both the underutilization and the overutilization of antibiotics based on the results of molecular testing. Overall, Alere i showed superior performance over BD Veritor in the detection of GAS pharyngitis and could potentially assist in better antibiotic utilization.

Accurate Detection of Streptococcus pyogenes at the Point of Care Using the cobas Liat Strep A Nucleic Acid Test

The performance of a polymerase chain reaction-based point-of-care assay, the cobas Strep A Nucleic Acid Test for use on the cobas Liat System (cobas Liat Strep A assay), for the detection of group A Streptococcus bacteria was evaluated in primary care settings. Throat swab specimens from 427 patients were tested with the cobas Liat Strep A assay and a rapid antigen detection test (RADT) by existing medical staff at 5 primary care clinics, and results were compared with bacterial culture. The cobas Liat Strep A assay demonstrated equivalent sensitivity (97.7%) and specificity (93.3%) to reference culture with a 15-minute turnaround time. In comparison to RADTs, the cobas Liat Strep A assay showed improved sensitivity (97.7% Liat vs 84.5% RADT). The Clinical Laboratory Improvement Amendments-waived cobas Liat Strep A assay demonstrated the ease of use and improved turnaround time of RADTs along with the sensitivity of culture.

STARD 2015 guidelines for reporting diagnostic accuracy studies: explanation and elaboration

Diagnostic accuracy studies are, like other clinical studies, at risk of bias due to shortcomings in design and conduct, and the results of a diagnostic accuracy study may not apply to other patient groups and settings. Readers of study reports need to be informed about study design and conduct, in sufficient detail to judge the trustworthiness and applicability of the study findings. The STARD statement (Standards for Reporting of Diagnostic Accuracy Studies) was developed to improve the completeness and transparency of reports of diagnostic accuracy studies. STARD contains a list of essential items that can be used as a checklist, by authors, reviewers and other readers, to ensure that a report of a diagnostic accuracy study contains the necessary information. STARD was recently updated. All updated STARD materials, including the checklist, are available at http://www.equator-network.org/reporting-guidelines/stard Here, we present the STARD 2015 explanation and elaboration document. Through commented examples of appropriate reporting, we clarify the rationale for each of the 30 items on the STARD 2015 checklist, and describe what is expected from authors in developing sufficiently informative study reports.

Rapid antigen detection test for group A streptococcus in children with pharyngitis

BACKGROUND

Group A streptococcus (GAS) accounts for 20% to 40% of cases of pharyngitis in children; the remaining cases are caused by viruses. Compared with throat culture, rapid antigen detection tests (RADTs) offer diagnosis at the point of care (within five to 10 minutes).

OBJECTIVES

To determine the diagnostic accuracy of RADTs for diagnosing GAS in children with pharyngitis. To assess the relative diagnostic accuracy of the two major types of RADTs (enzyme immunoassays (EIA) and optical immunoassays (OIA)) by indirect and direct comparison.

SEARCH METHODS

We searched CENTRAL, MEDLINE, EMBASE, Web of Science, CDSR, DARE, MEDION and TRIP (January 1980 to July 2015). We also conducted related citations tracking via PubMed, handsearched reference lists of included studies and relevant review articles, and screened all articles citing included studies via Google Scholar.

SELECTION CRITERIA

We included studies that compared RADT for GAS pharyngitis with throat culture on a blood agar plate in a microbiology laboratory in children seen in ambulatory care.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for relevance, assessed full texts for inclusion, and carried out data extraction and quality assessment using the QUADAS-2 tool. We used bivariate meta-analysis to estimate summary sensitivity and specificity, and to investigate heterogeneity across studies. We compared the accuracy of EIA and OIA tests using indirect and direct evidence.

MAIN RESULTS

We included 98 unique studies in the review (116 test evaluations; 101,121 participants). The overall methodological quality of included studies was poor, mainly because many studies were at high risk of bias regarding patient selection and the reference standard used (in 73% and 43% of test evaluations, respectively). In studies in which all participants underwent both RADT and throat culture (105 test evaluations; 58,244 participants; median prevalence of participants with GAS was 29.5%), RADT had a summary sensitivity of 85.6%; 95% confidence interval (CI) 83.3 to 87.6 and a summary specificity of 95.4%; 95% CI 94.5 to 96.2. There was substantial heterogeneity in sensitivity across studies; specificity was more stable. There was no evidence of a trade-off between sensitivity and specificity. Heterogeneity in accuracy was not explained by study-level characteristics such as whether an enrichment broth was used before plating, mean age and clinical severity of participants, and GAS prevalence. The sensitivity of EIA and OIA tests was comparable (summary sensitivity 85.4% versus 86.2%). Sensitivity analyses showed that summary estimates of sensitivity and specificity were stable in low risk of bias studies.

AUTHORS' CONCLUSIONS

In a population of 1000 children with a GAS prevalence of 30%, 43 patients with GAS will be missed. Whether or not RADT can be used as a stand-alone test to rule out GAS will depend mainly on the epidemiological context. The sensitivity of EIA and OIA tests seems comparable. RADT specificity is sufficiently high to ensure against unnecessary use of antibiotics. Based on these results, we would expect that amongst 100 children with strep throat, 86 would be correctly detected with the rapid test while 14 would be missed and not receive antibiotic treatment.

Scarlet fever: A not so typical exanthematous pharyngotonsillitis (based on 171 cases)

AIM

To describe the age, signs and clinical symptoms of children with scarlet fever at the present time, and to check whether they are equivalent to those with traditional streptococcal pharyngotonsillitis.

STUDY DESIGN

An observational, retrospective study was conducted on the clinical records of 5500 children aged from 0 to 15 years attending a primary health care center. A record was made of the percentage of the cases in which signs and symptoms appear and the Centor score was calculated. Microbiological diagnosis of the disease was made using the rapid antigen-detection test or traditional culture.

RESULTS

A total of 171 out of 252 scarlet fever diagnoses were microbiologically verified in 158 patients. The median age was 3.8 years (interquartile range: 2.91-4.78), with the majority (57%) under the age of 4 years. There was fever in 89% of the processes (95% CI: 84-94%), with a temperature of >38°C in 73% (95% CI: 65-80%), enlarged lymph nodes in 70% (95% CI: 58-82%), absence of cough in 73% (95% CI: 65-80%), and tonsillar exudate in only 24% (95% CI: 17-31%). The Centor score (n=105) was ≤2 points in 86% (95% CI: 79-92%). The only difference regarding age is that episodes in patients under the age of 4 years old have significantly higher fever (>38°C) than the older ones (80% versus 63%. OR 3.13; 95% CI: 1.46-6.71).

CONCLUSION

Scarlet fever pharyngotonsillitis differs from the traditional streptococcal pharyngotonsillitis, and its evaluation using clinical prediction rules such as Centor or McIsaac is questionable. The main diagnostic key must certainly be rash, regardless of patient age.

Pharyngitis: soothing the sore throat

Sore throat is a common presentation in primary care. Accurate identification of cause is important for appropriate treatment. Clinical scoring systems and diagnostic tests are recommended to identify group A beta-hemolytic streptococcus, which warrants guideline-driven therapy. The article explores causes, diagnosis, management, and possible complications of pharyngitis.

Randomised, double-blind, placebo-controlled studies on flurbiprofen 8.75 mg lozenges in patients with/without group A or C streptococcal throat infection, with an assessment of clinicians' prediction of 'strep throat'

BACKGROUND

Diagnosing group A streptococcus (Strep A) throat infection by clinical examination is difficult, and misdiagnosis may lead to inappropriate antibiotic use. Most patients with sore throat seek symptom relief rather than antibiotics, therefore, therapies that relieve symptoms should be recommended to patients. We report two clinical trials on the efficacy and safety of flurbiprofen 8.75 mg lozenge in patients with and without streptococcal sore throat.

METHODS

The studies enrolled adults with moderate-to-severe throat symptoms (sore throat pain, difficulty swallowing and swollen throat) and a diagnosis of pharyngitis. The practitioner assessed the likelihood of Strep A infection based on historical and clinical findings. Patients were randomised to flurbiprofen 8.75 mg or placebo lozenges under double-blind conditions and reported the three throat symptoms at baseline and at regular intervals over 24 h.

RESULTS

A total of 402 patients received study medication (n = 203 flurbiprofen, n = 199 placebo). Throat culture identified Strep A in 10.0% of patients and group C streptococcus (Strep C) in a further 14.0%. The practitioners' assessments correctly diagnosed Strep A in 11/40 cases (sensitivity 27.5%, and specificity 79.7%). A single flurbiprofen lozenge provided significantly greater relief than placebo for all three throat symptoms, lasting 3-4 h for patients with and without Strep A/C. Multiple doses of flurbiprofen lozenges over 24 h also led to symptom relief, although not statistically significant in the Strep A/C group. There were no serious adverse events.

CONCLUSIONS

The results highlight the challenge of identifying Strep A based on clinical features. With the growing problem of antibiotic resistance, non-antibiotic treatments should be considered. As demonstrated here, flurbiprofen 8.75 mg lozenges are an effective therapeutic option, providing immediate and long-lasting symptom relief in patients with and without Strep A/C infection.

Selective testing strategies for diagnosing group A streptococcal infection in children with pharyngitis: a systematic review and prospective multicentre external validation study

BACKGROUND

Several clinical prediction rules for diagnosing group A streptococcal infection in children with pharyngitis are available. We aimed to compare the diagnostic accuracy of rules-based selective testing strategies in a prospective cohort of children with pharyngitis.

METHODS

We identified clinical prediction rules through a systematic search of MEDLINE and Embase (1975-2014), which we then validated in a prospective cohort involving French children who presented with pharyngitis during a 1-year period (2010-2011). We diagnosed infection with group A streptococcus using two throat swabs: one obtained for a rapid antigen detection test (StreptAtest, Dectrapharm) and one obtained for culture (reference standard). We validated rules-based selective testing strategies as follows: low risk of group A streptococcal infection, no further testing or antibiotic therapy needed; intermediate risk of infection, rapid antigen detection for all patients and antibiotic therapy for those with a positive test result; and high risk of infection, empiric antibiotic treatment.

RESULTS

We identified 8 clinical prediction rules, 6 of which could be prospectively validated. Sensitivity and specificity of rules-based selective testing strategies ranged from 66% (95% confidence interval [CI] 61-72) to 94% (95% CI 92-97) and from 40% (95% CI 35-45) to 88% (95% CI 85-91), respectively. Use of rapid antigen detection testing following the clinical prediction rule ranged from 24% (95% CI 21-27) to 86% (95% CI 84-89). None of the rules-based selective testing strategies achieved our diagnostic accuracy target (sensitivity and specificity>85%).

INTERPRETATION

Rules-based selective testing strategies did not show sufficient diagnostic accuracy in this study population. The relevance of clinical prediction rules for determining which children with pharyngitis should undergo a rapid antigen detection test remains questionable.

Rapid antigen group A streptococcus test to diagnose pharyngitis: a systematic review and meta-analysis

Background

Pharyngitis management guidelines include estimates of the test characteristics of rapid antigen streptococcus tests (RAST) using a non-systematic approach.

Objective

To examine the sensitivity and specificity, and sources of variability, of RAST for diagnosing group A streptococcal (GAS) pharyngitis.

Data Sources

MEDLINE, Cochrane Reviews, Centre for Reviews and Dissemination, Scopus, SciELO, CINAHL, guidelines, 2000–2012.

Study Selection

Culture as reference standard, all languages.

Data Extraction and Synthesis

Study characteristics, quality.

Main Outcome(s) and Measure(s)

Sensitivity, specificity.

Results

We included 59 studies encompassing 55,766 patients. Forty three studies (18,464 patients) fulfilled the higher quality definition (at least 50 patients, prospective data collection, and no significant biases) and 16 (35,634 patients) did not. For the higher quality immunochromatographic methods in children (10,325 patients), heterogeneity was high for sensitivity (inconsistency [I²] 88%) and specificity (I² 86%). For enzyme immunoassay in children (342 patients), the pooled sensitivity was 86% (95% CI, 79–92%) and the pooled specificity was 92% (95% CI, 88–95%). For the higher quality immunochromatographic methods in the adult population (1,216 patients), the pooled sensitivity was 91% (95% CI, 87 to 94%) and the pooled specificity was 93% (95% CI, 92 to 95%); however, heterogeneity was modest for sensitivity (I² 61%) and specificity (I² 72%). For enzyme immunoassay in the adult population (333 patients), the pooled sensitivity was 86% (95% CI, 81–91%) and the pooled specificity was 97% (95% CI, 96 to 99%); however, heterogeneity was high for sensitivity and specificity (both, I² 88%).

Conclusions

RAST immunochromatographic methods appear to be very sensitive and highly specific to diagnose group A streptococcal pharyngitis among adults but not in children. We could not identify sources of variability among higher quality studies. The present systematic review provides the best evidence for the wide range of sensitivity included in current guidelines.

Rapid diagnostic tests for group A streptococcal pharyngitis: a meta-analysis

BACKGROUND AND OBJECTIVE

Effective management of group A streptococcal (GAS) pharyngitis is hindered by impracticality of the gold standard diagnostic test: throat culture. Rapid antigen diagnostic tests (RADTs) are a promising alternative, although concerns about their sensitivity and specificity, and variation between test methodologies, have limited their clinical use. The objective of this study was to perform a systematic review with meta-analysis of the diagnostic accuracy of RADTs for GAS pharyngitis.

METHODS

Medline and Embase from 1996 to 2013 were used as data sources. Of 159 identified studies, 48 studies of diagnostic accuracy of GAS RADTs using throat culture on blood agar as a reference standard were selected. Bivariate random-effects regression was used to estimate sensitivity and specificity with 95% confidence intervals (CIs). Additional meta-analyses were performed for pediatric data.

RESULTS

A total of 60 pairs of sensitivity and specificity from 48 studies were included. Overall summary estimates for sensitivity and specificity of RADTs were 0.86 (95% CI 0.83 to 0.88) and 0.96 (95% CI 0.94 to 0.97), respectively, and estimates for pediatric data were similar. Molecular-based RADTs had the best diagnostic accuracy. Considerable variability exists in methodology between studies. There were insufficient studies to allow meta-regression/subgroup analysis within each test type.

CONCLUSIONS

RADTs can be used for accurate diagnosis of GAS pharyngitis to streamline management of sore throat in primary care. RADTs may not require culture backup for negative tests in most low-incidence rheumatic fever settings. Newer molecular tests have the highest sensitivity, but are not true point-of-care tests.

Bacterial prevalence and antimicrobial prescribing trends for acute respiratory tract infections

BACKGROUND AND OBJECTIVES

Antimicrobials are frequently prescribed for acute respiratory tract infections (ARTI), although many are viral. We aimed to determine bacterial prevalence rates for 5 common childhood ARTI - acute otitis media (AOM), sinusitis, bronchitis, upper respiratory tract infection, and pharyngitis- and to compare these rates to nationally representative antimicrobial prescription rates for these ARTI.

METHODS

We performed (1) a meta-analysis of English language pediatric studies published between 2000 and 2011 in Medline, Embase, and the Cochrane library to determine ARTI bacterial prevalence rates; and (2) a retrospective cohort analysis of children age <18 years evaluated in ambulatory clinics sampled by the 2000-2010 National Ambulatory Medical Care Survey (NAMCS) to determine estimated US ARTI antimicrobial prescribing rates.

RESULTS

From the meta-analysis, the AOM bacterial prevalence was 64.7% (95% confidence interval [CI], 50.5%-77.7%); Streptococcus pyogenes prevalence during pharyngitis was 20.2% (95% CI, 15.9%-25.2%). No URI or bronchitis studies met inclusion criteria, and 1 sinusitis study met inclusion criteria, identifying bacteria in 78% of subjects. Based on these condition-specific bacterial prevalence rates, the expected antimicrobial rescribing rate for ARTI overall was 27.4% (95% CI, 26.5%-28.3%). However, antimicrobial agents were prescribed in NAMCS during 56.9% (95% CI, 50.8%-63.1%) of ARTI encounters, representing an estimated 11.4 million potentially preventable antimicrobial prescriptions annually.

CONCLUSIONS

An estimated 27.4% of US children who have ARTI have bacterial illness in the post-pneumococcal conjugate vaccine era. Antimicrobials are prescribed almost twice as often as expected during outpatient ARTI visits, representing an important target for ongoing antimicrobial stewardship interventions.

Promoting prudent use of antibiotics: the experience from a multifaceted regional campaign in Greece

Background

Antibiotic resistance, a major public health problem, has been linked to antibiotic consumption. In Greece both consumption and resistance rates are among the highest in Europe. A multifaceted campaign targeting both physicians and parents of school children was implemented for the first time in order to educate the public and update doctors, aiming to promote judicious use of antibiotics and hopefully decrease its consumption.

Methods

The programme consisted of a public education campaign and academic detailing of primary care physicians in the district of Corinth in Peloponnese. The experience and perceptions of parents were recorded in the meetings in the form of course evaluation and assessment, anonymous questionnaires. The use of Rapid Antigen Detection Test (RADT) for streptococcal pharyngitis by primary care physicians was also assessed by use of anonymous questionnaires. Antibiotic consumption was compared before and after the programme between the district of Corinth and the other districts of Peloponnese, as well as at a national level.

Results

Antibiotic consumption remained unaltered at 26 Defined daily doses per 1000 Inhabitants per Day (DID) in accordance with the trend in other regions and at a national level. However, the utilization of Amoxycillin and Penicillin was increased by 34.3%, while the use of other antimicrobial classes including macrolides, cephalosporins and fluoroquinolones decreased by 6.4-21.9%. The use of RADT did not lead to a significantly decreased antimicrobial consumption.

Conclusions

A multifaceted educational programme targeting both the general public and primary care physicians was associated with rationalization in the choice of antimicrobial. A reduction in the total antimicrobial consumption was not achieved.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-866) contains supplementary material, which is available to authorized users.

Impact of the rapid antigen detection test in diagnosis and treatment of acute pharyngotonsillitis in a pediatric emergency room

OBJECTIVE

To evaluate the impact of the routine use of rapid antigen detection test in the diagnosis and treatment of acute pharyngotonsillitis in children.

METHODS

This is a prospective and observational study, with a protocol compliance design established at the Emergency Unit of the University Hospital of Universidade de São Paulo for the care of children and adolescents diagnosed with acute pharyngitis.

RESULTS

650 children and adolescents were enrolled. Based on clinical findings, antibiotics would be prescribed for 389 patients (59.8%); using the rapid antigen detection test, they were prescribed for 286 patients (44.0%). Among the 261 children who would not have received antibiotics based on the clinical evaluation, 111 (42.5%) had positive rapid antigen detection test. The diagnosis based only on clinical evaluation showed 61.1% sensitivity, 47.7% specificity, 44.9% positive predictive value, and 57.5% negative predictive value.

CONCLUSIONS

The clinical diagnosis of streptococcal pharyngotonsillitis had low sensitivity and specificity. The routine use of rapid antigen detection test led to the reduction of antibiotic use and the identification of a risk group for complications of streptococcal infection, since 42.5% positive rapid antigen detection test patients would not have received antibiotics based only on clinical diagnosis.

Empirical validation of Polish guidelines for the management of acute streptococcal pharyngitis in children

OBJECTIVE

Group A Streptococcus (GAS) pharyngitis is currently the only commonly occurring form of acute pharyngitis for which antibiotic therapy is definitely indicated. Polish guidelines advocate the use of modified Centor score (MCS) to assess the probability of GAS pharyngitis. They advise performing throat culture or rapid antigen detection test (RADT) in children with score 2-3 in MCS and treating with antibiotic only those in whom GAS was detected. Negative RADT results should be confirmed by culture. In children with score 4, the guidelines allow to introduce empiric antibiotic therapy. Phenoxymethyl penicillin is recommended as a drug of choice to treat GAS pharyngitis. The aim of our study was to evaluate the accuracy of strategy recommended by Polish guidelines in identifying those children with acute pharyngitis who require antibiotic treatment. Hence, diagnostic values of score 4 in MCS and RADT were assessed using throat culture as a reference standard. Phenoxymethyl penicillin efficacy in GAS eradication and prevention of post-streptococcal complications were estimated as well.

METHODS

Ninety children between 2 and 15 years of age with acute pharyngitis symptoms suggesting GAS etiology (MCS ≥ 2), participated in our study. At the initial visit MCS was evaluated and two throat swabs were collected to perform RADT and culture. In children with GAS pharyngitis treated with penicillin, microbiological cure was assessed by performing two control throat cultures. Next, children were under observation for 3 months.

RESULTS

Positive predictive value of score 4 in MCS turned out to be 48.05% (95% CI: 36.5-59.7%). RADT sensitivity, specificity and diagnostic accuracy proved to be 100%, 96%, and 98%, respectively. GAS eradication rate in children treated with penicillin turned out to be 92.5%. No post-streptococcal sequelae occurred in any child in 3-month observation.

CONCLUSIONS

Empiric antibiotic therapy in children with score 4 in MCS will result in significant overtreatment of those with nonstreptococcal pharyngitis. New generation RADT diagnostic value in GAS detection proved to be equivalent to that of culture, which obviates the need of backup culture in children with negative RADT results. Phenoxymethyl penicillin revealed high eradication efficacy and proved to prevent post-streptococcal sequelae in children with acute GAS pharyngitis.

Streptococcal pharyngitis in children: a meta-analysis of clinical decision rules and their clinical variables

OBJECTIVE

To identify the best clinical decision rules (CDRs) for diagnosing group A streptococcal (GAS) pharyngitis in children. A combination of symptoms could help clinicians exclude GAS infection in children with pharyngitis.

DESIGN

Systematic review and meta-analysis of original articles involving CDRs in children. The Pubmed, OVID, Institute for Scientific and Technical Information and Cochrane databases from 1975 to 2010 were screened for articles that derived or validated a CDR on a paediatric population: 171 references were identified.

SETTING

Any reference including primary care for children with pharyngitis.

DATA EXTRACTION

The methodological quality of the articles selected was analysed according to published quality standards. A meta-analysis was performed to assess the statistical performance of the CDRs and their variables for the diagnosis of GAS pharyngitis.

PRIMARY OUTCOME MEASURE

The main criterion was a false-negative rate in the whole population not any worse than that of a rapid diagnostic test strategy for all patients (high sensitivity and low negative likelihood ratio).

RESULTS

4 derived and 12 validated CDRs for this diagnosis in children. These articles involved 10 523 children (mean age, 7 years; mean prevalence of GAS pharyngitis, 34%). No single variable was sufficient for diagnosis. Among the CDRs, that of Joachim et al had a negative likelihood ratio of 0.3 (95% CI 0.2 to 0.5), resulting in a post-test probability of 13%, which leads to 3.6% false-negative rate among low-risk patients and 10.8% overall, equivalent to rapid diagnostic tests in some studies.

CONCLUSIONS

The rule of Joachim et al could be useful for clinicians who do not use rapid diagnostic tests and should allow avoiding antibiotic treatment for the 35% of children identified by the rule as not having GAS pharyngitis. Owing to its poor specificity, such CDR should be used to focus rapid diagnostic tests to children with high risk of GAS pharyngitis to reduce the antibiotic consumption.

Management of acute streptococcal pharyngitis: still the subject of controversy

Although most cases of acute pharyngitis are viral in origin, antibiotics are overused in its treatment. Streptococcus pyogenes (group A streptococcus, GAS), the principal bacterial pathogen of acute sore throat, is responsible for merely 5–30% of cases. Moreover, GAS pharyngitis is currently the only commonly occurring form of acute pharyngitis for which antibiotic therapy is definitely indicated. Therefore the differentiation between GAS pharyngitis and that of viral etiology is crucial. Accordingly, scientific societies as well as respected advisory bodies in Europe and North America, issued guidelines for the management of acute pharyngitis with the aim of minimizing unnecessary antibiotic prescriptions in its treatment. The aim of this review work is to confront the state of the art in acute GAS pharyngitis diagnosis and treatment with different approaches to its management represented by current European and North American guidelines. Although based on scientific evidence, international guidelines differ substantially in opinions whether GAS pharyngitis diagnosis should be based on microbiological testing, clinical algorithm or a combination of both. On the other hand, some European guidelines consider GAS pharyngitis to be a mild, self-limiting disease that does not require a specific diagnosis or antimicrobial treatment except in high-risk patients. There is an agreement among guidelines that if antibiotic therapy is indicated, phenoxymethyl penicillin should be the drug of choice to treat GAS pharyngitis.