Better diagnosis and treatment of throat infections caused by group A β-haemolytic streptococci

Diagnosis of group A streptococcal pharyngitis in the paediatric emergency department using a fluorescence-based RADT: predicted impact on antibiotic prescription

Introduction. Using rapid antigen diagnostic tests (RADTs) in clinical practice has shown excellent specificity but often has diminished sensitivity.Gap Statement. Local data for evaluating the diagnostic performance of a new fluorescence-based RADT and its influence on the antibiotic prescription rate are not available.Aim. To evaluate the accuracy of fluorescent immunoassay (FIA)-RADTs for diagnosing group A streptococcal (GAS) pharyngitis among children and its estimated effect as a point of care test (POCT) on the antibiotic prescription rate at the paediatric emergency department.Methodology. A prospective study was conducted, comprising children 3 to 14 years old presenting with pharyngitis. Throat swab culture and FIA-RADTs were performed on all samples. Conventional PCR was performed on the discordant samples.Results. A total of 246 children were included in this study. The sensitivity, specificity, and positive and negative predictive values of the FIA-RADT, based on culture results and PCR detection combined, were 95.6, 96.8, 94.6 and 97.4 %, respectively. Antibiotics have been prescribed to 162 (65.9 %) children; however, if FIA-RADTs had been added in the clinical practice as a POCT, only 92 (37.4 %) children would have received antibiotics in total. Additionally, implementation of FIA-RADTs would significantly reduce the antibiotic prescription rate from 48.8 and 60.6 % to 9.5 and 31.9 % among patients with clinical scores of 2 and 3, respectively.Conclusion. The new FIA-RADT is simple, prompt and reliable. It is helpful in clinical settings and may be used to reduce antibiotic overprescription, especially for children who have a low risk for GAS pharyngitis, according to the clinical score.

[The significance of antistreptolysin O characteristics for the determination of indications for tonsillectomy in the children]

The objective of the present work was to evaluate the diagnostic significance of the measurement of the antistreptolysin O (ASLO) titers in the children presenting with chronic tonsillitis for determining the indications for tonsillectomy. The study included 54 patients at the age varying from 4 to 17 years who had undergone bilateral tonsillectomy for the treatment of chronic tonsillitis. The diagnosis was confirmed by the results of the histological study of the removed amygdalae. Prior to surgery, all the patients had been subjected to the bacteriological investigation of the smears taken from the surface of the palatal tonsils. The titers of antistreptolysin O in the serum were determined with the use of the kinetic nephelometric technique before, 6 and 12 months after the surgical intervention. The results of the measurements were treated using the Statzilla software package (version 3.2, R Foundation for Statistical Computing, Vienna, Austria). Streptococcus pyogenes (group A) was identified only in 7 (13%) patients. The initially enhanced content of ASLO ranging from 273 to 1880 IU/ml was documented in 42 (77.7%) of the 54 patients. Twelve patients had the ASLO titers within the normal limits (from 13 to 124 IU/ml). The removal of palatal tonsils resulted in a significant decrease of the ASLO titers in the patients who had presented with the initially enhanced content of antistreptolysin O (p < 0.05); nevertheless, their ASLO titers remained higher than the normal values in 69% and 82% of the patients examined within 6 and 12 months after the surgical intervention, respectively. The patients who had exhibited the high levels of antistreptolysin O during the preoperative period did not experience normalization of this parameter after surgery. It is concluded, taking into account the absence of correlation between the enhancement of serum antistreptolysin O titers and the presence of group A beta-chemolytic Streptococci (BCSA), that the result of the measurement of ASLO titers can not be considered as a valid indication for tonsillectomy in the children.

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.

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.

The pattern of acute rheumatic fever in children: Experience at the children's hospital, Riyadh, Saudi Arabia

BACKGROUND

The study was carried out in Riyadh City Hospital to determine the hospital prevalence of acute rheumatic fever (ARF), its characteristics and to determine the proportion of the ARF population that have recurrent attacks.

METHODS

The study was an analysis of 83 children with ARF, admitted to the Children's Hospital, Riyadh, over a 10-year period (1994-2003). The diagnosis of ARF was based on clinical features as defined in the modified Jones criteria with evidence of recent streptococcal infection. The diagnosis of recurrence of rheumatic fever in children with rheumatic heart disease was based on the presence of one major criterion apart from carditis or two minor criteria, in addition to evidence of preceding streptococcal infection.

RESULTS

The mean age at presentation was 9 years. In 31 (37%) cases, arthritis was the only major Jones criterion. In 30 (36%) others, arthritis was associated with carditis and in 3 (4%), with chorea. Cardiac involvement was documented in 44 (53%) cases; it occurred alone in 5 (6%), with arthritis in 30 (36%), and with chorea in 9 (11%) others. Among the 44 with carditis, the pattern of cardiac involvement was valvular only (mild carditis) in 30 (68%), while it was severe in the remaining 14 (32%) cases who also had heart failure. The involvement of the mitral valve alone occurred in 26 (59%) cases in the form mitral regurgitation, while both aortic and mitral valve regurgitation were present in 11 (25%) cases, and aortic valve regurgitation alone in four (9%) others. Chorea was the only major criterion of ARF in 5 children (6%), while it occurred in association with other major criteria in 12 (15%) others. Nineteen (23%) children had recurrent attacks of ARF.

CONCLUSION

ARF continues to occur in Saudi Arabia in the period (1994-2003), despite the progress made in the socio-economic development of the country, and this is often associated with severe cardiac involvement.

Accuracy and precision of the signs and symptoms of streptococcal pharyngitis in children: a systematic review

OBJECTIVE

To conduct a systematic review to determine whether clinical findings can be used to rule in or to rule out streptococcal pharyngitis in children.

STUDY DESIGN

Two authors independently searched MEDLINE and EMBASE. We included articles if they contained data on the accuracy of symptoms or signs of streptococcal pharyngitis, individually or combined into prediction rules, in children 3-18 years of age.

RESULTS

Thirty-eight articles with data on individual symptoms and signs and 15 articles with data on prediction rules met all inclusion criteria. In children with sore throat, the presence of a scarlatiniform rash (likelihood ratio [LR], 3.91; 95% CI, 2.00-7.62), palatal petechiae (LR, 2.69; CI, 1.92-3.77), pharyngeal exudates (LR, 1.85; CI, 1.58-2.16), vomiting (LR, 1.79; CI, 1.58-2.16), and tender cervical nodes (LR, 1.72; CI, 1.54-1.93) were moderately useful in identifying those with streptococcal pharyngitis. Nevertheless, no individual symptoms or signs were effective in ruling in or ruling out streptococcal pharyngitis.

CONCLUSIONS

Symptoms and signs, either individually or combined into prediction rules, cannot be used to definitively diagnose or rule out streptococcal pharyngitis.

High incidence of rheumatic fever and rheumatic heart disease in the republics of Central Asia

The epidemiological situation involving rheumatic fever (RF) and rheumatic heart disease (RHD) not only remains unresolved but is also a cause of serious concern due to the rapid increase in the incidence of RF/RHD in many developing countries. After the collapse of the Soviet Union, the republics of Central Asia experienced an economic decline that directly affected the public health sector of this region. This is the main cause of the high prevalence of many infectious diseases in Central Asia, including streptococcal tonsillopharyngitis, which carries the risk of complications such as RF. The difficulty involved in early diagnosis of RF and the development of RHD among children and adolescents causes early mortality and sudden death, leading to economic damage in these countries due to the loss of the young working population. Among all the developing countries, Kyrgyzstan, which is located in the heart of Central Asia, has the highest prevalence of RF/RHD. The increase in the prevalence of RF in Central Asia can be attributed to factors such as the low standard of living and changes in the virulence of streptococci and their sensitivity to antibiotics.

[Evaluation of rapid methods for detecting Streptococcus pyogenes. Systematic review and meta-analysis]

INTRODUCTION

Streptococcal pharyngitis is one of the most frequent reasons for consultations in primary and paediatric care. An inadequate treatment could cause adverse effects and bacterial resistance. The rapid antigen tests are an important advance, enabling the diagnosis of infection by Streptococcus pyogenes to be diagnosed in a few minutes. The aim of this review is to assess the rapid antigen-detection test in the diagnosis of S. pyogenes from throat samples.

MATERIAL AND METHODS

Systematic review and meta-analysis (2000-09). Source database: MedLine, Embase, Cochrane Library, Cinahl, CRD, ECRI, Hayes and HTA's agencies. The quality of included studies was measured according to Quadas's criteria. The diagnostic validity indices have been calculated. A meta-analysis was performed in order to synthesize the results of the different evaluated studies.

RESULTS

Twenty four studies were included. The quality was moderate. The sensitivity ranged between 65.6% and 96.4%; specificity from 68.7%-99.3%; the positive predictive value was between 59.4%-97.4%; and the negative predictive value from 87.8%-98%. The meta-analysis determined an overall sensitivity of 0.85 [95% CI, 0.84-0.87], specificity was 0.96 [95% CI, 0.96-0.97], likelihood ratio (+) 22.21 [95% CI, 15.12-32.63], and likelihood ratio (-) 0.15 [95% CI, 0.13-0.18]. The rapid antigen-detection test demonstrated a good diagnostic performance.

CONCLUSIONS

Rapid tests offer good accuracy for use as diagnostic method, however, these devices have to be complemented with the microbiological culture, because there are false positive and negative results.

Impact of rapid streptococcal test on antibiotic use in a pediatric emergency department

Acute pharyngitis is commonly seen in children. Group A beta-hemolytic Streptococcus is the most common bacterial cause of acute pharyngitis and accounts for approximately 15% to 30% of cases in children, but this condition is generally overdiagnosed and overtreated. The availability of rapid streptococcal tests (RSTs) have made this diagnosis simpler and reduced the use of antibiotics. Overuse of antibiotics leads to drug-resistant bacterial strains. Reducing the number of antibiotic prescriptions provided for upper respiratory tract infections has been strongly recommended to limit bacterial resistance.

OBJECTIVE

To assess the impact of RSTs on antibiotic prescriptions in children with pharyngitis in the emergency department.

METHODS

A retrospective study from September 2005 to September 2007 of all patients (3-18 years old) presenting to the pediatric emergency department with sore throat as the chief complaint or suspected clinically to have acute pharyngitis and who had an RST performed. Patients with a negative RST result had a culture performed. The information of the patients with the diagnosis of pharyngitis was also collected in a 2-year control period before the availability of the test. Patients with a negative RST result had a culture performed. In addition, the antibiotic prescriptions for these patients were also recorded.

RESULTS

A total of 8280 patients were included in the study. Throat culture results of 1723 patients were reviewed in the pre-RST phase. During the post-RST phase, 6557 children underwent RST. The RST results were positive in 1474 children (22.5%) and negative in 5083 patients (77.5%). Rapid strep testing was associated with a lower antibiotic prescription rate for children with pharyngitis (41.38% for those treated in the pre-RST phase versus 22.45% for those treated in the post-RST phase; P < 0.001).

CONCLUSIONS

The availability of a RST could substantially reduce the unnecessary prescription of antibiotics. This study supports the screening of all children with pharyngitis by performing an RST to guide decision making for antibiotic administration. This strategy has a significant impact on reducing the antibiotic prescription rate to almost 50%. In addition, only 2 children (0.04%) had negative rapid antigen test results with cultures positive for Streptococcus.