Extrapharyngeal group A Streptococcus infection: diagnostic accuracy and utility of rapid antigen testing

Diagnostic Accuracy of Group A Streptococcus Rapid Antigen Detection Test on Middle Ear Fluid in Children With Acute Otitis Media With Spontaneous Perforation: A Prospective Multicenter Evaluation

Group A Streptococcus is one of the leading causes of otorrhea. The performance of rapid antigen tests in 256 children with otorrhea showed excellent sensitivity, 97.3% (95% confidence interval: 90.7%-99.7%), and specificity, 100% (95% confidence interval: 98.0%-100%). In a period of increasing invasive and noninvasive group A Streptococcus infections, an early diagnosis could be useful.

Surveillance of noninvasive group A Streptococcus infections in French ambulatory pediatrics before and during the COVID-19 pandemic: a prospective multicenter study from 2018-2022

OBJECTIVES

We evaluated the burden of noninvasive group A Streptococcus (GAS) infections in ambulatory pediatrics before and during the COVID-19 pandemic in France.

METHODS

We analyzed data from a national network of ambulatory pediatricians between 2018 and 2022. Clinicians evaluating children ≤15 years old for tonsillopharyngitis, perianal infections, paronychia/blistering dactylitis, and scarlet fever were invited to perform a rapid antigen detection test (RADT) for GAS. Monthly incidence of noninvasive GAS infections per 10,000 visits was modeled using time series analysis, considering two breakpoints: March 2020 (first national lockdown) and March 2022 (end of mandatory mask-wearing in schools).

RESULTS

Over the study period, 125 pediatricians recorded 271,084 infectious episodes. GAS-related illnesses represented 4.3% of all infections. In March 2020, the incidence of GAS diseases decreased by 84.5% (P <0.001), with no significant trend until March 2022. After March 2022, the incidence significantly increased (+23.8% per month, P <0.001), with similar patterns across all monitored GAS-related diseases.

CONCLUSION

By using routine clinical data and RADTs, we have monitored changes in the incidence of noninvasive GAS infections in ambulatory pediatrics. COVID-19 mitigation measures have had a major impact on the epidemiology of noninvasive GAS infections, but their relaxation was followed by a surge above baseline levels.

Group A Streptococcal Paronychia and Blistering Distal Dactylitis in Children: Diagnostic Accuracy of a Rapid Diagnostic Test and Efficacy of Antibiotic Treatment

Among 174 children with blistering distal dactylitis or paronychia, 36.2% had a positive group A Streptococcus (GAS) rapid detection antigen. For GAS, the outcome for patients who received amoxicillin was favorable in all cases without any surgical procedures; 44.6% of cases due to Staphylococcus aureus infection (38.7%) required surgery.

Perianal infectious dermatitis: An underdiagnosed, unremitting and stubborn condition

Perianal infectious dermatitis (PID) represents a superficial inflammation of the perianal skin, which is of bacterial origin (classically, group A beta-hemolytic streptococci). This narrative review aims to critically review and summarize the available scientific literature regarding pediatric PID, being the first of its kind, to the best of the author’s knowledge. It also reports the first cases of Romanian children with PID. Multiple databases were subjected to systematic literature search (from 1966 to April 30, 2018) to identify studies and case reports of children with PID. As such, this review provides updated information about essential aspects of PID (epidemiology, etiology, pathogenesis, as well as clinical features, required investigations and therapeutic options) and of diagnostic pitfalls. Although a well-defined entity, PID remains largely underdiagnosed. PID may mimic other common conditions with skin manifestations (like candidiasis, pinworms, eczema, irritant dermatitis, anal fissure, hemorrhoids, Crohn’s disease, psoriasis, seborrheic dermatitis, zinc deficiency dermatosis and even sexual abuse), with consequent unnecessary, sometimes expensive and invasive investigations and futile therapies, which cause patients and families discomfort and distress. Since PID has an unremitting course, early recognition is imperative, as it allows for prompt and efficacious antibiotic therapy. However, PID represents a stubborn condition and, even if properly treated, its recurrence rate remains high. Further well-designed prospective randomized controlled trials, with adequate follow-up, are required in order to formulate the optimum personalized antibiotic therapy (oral alone or in association with topical medication), able to prevent recurrences. Awareness of this condition by healthcare professionals should improve patient outcomes.

Reassessment of the Role of Rapid Antigen Detection Tests in Diagnosis of Invasive Group A Streptococcal Infections

Rapid antigen detection tests (RADTs) for group A streptococci (GAS) are widely used for diagnosing acute pharyngitis, which has led to a considerable reduction in antibiotic prescriptions over the past decade. Beyond this intended use, their reassessment on invasive samples may be relevant in the management of life-threatening GAS infections. To this end, we evaluated the performances of three RADTs, culture, GAS PCR, and 16S rRNA gene PCR assays, and compared them with a composite gold standard (GAS-PCR assay and/or culture) for the diagnosis of severe GAS infection. A total of 192 specimens from deep-tissue (mostly normally sterile) sites enriched for 75 GAS-positive samples were enrolled in the study. The three evaluated RADTs showed sensitivities ranging from 88.0% to 94.7% versus 98.7% for GAS PCR, 84% for 16S rRNA gene PCR, and 77.3% for culture. The sensitivities of the ImmunoCardSTAT! Strep A test (Meridian Bioscience) and the NADAL Strep A strip (Nal Von Minden) were similar to that of GAS PCR (P= 0.25 and 0.03, respectively) and higher than that of culture (P= 0.001 and 0.006, respectively), whereas the SD Bioline Strep A test strip (Standard Diagnostics) showed a performance similar to that of culture (P= 0.02). The three RADTs detected 10 distinctemmtypes, including a predominance ofemm1 (33.3%),emm89 (10.6%), andemm12 (7.6%). No false-positive results were observed, leading to a specificity of 100% for all the evaluated RADTs. The GAS RADTs turned out to be sensitive, specific, and easy-to-use tools that may aid in the management of invasive GAS infections in 24/7 point-of-care laboratories by enabling early diagnosis and focused therapy.

Clinical Perineal Streptococcal Infection in Children: Epidemiologic Features, Low Symptomatic Recurrence Rate after Treatment, and Risk Factors for Recurrence

OBJECTIVES

To evaluate the epidemiology of perineal streptococcal infection and recurrence rates following amoxicillin treatment.

STUDY DESIGN

We used laboratory logs in a single pediatric practice to identify patients 0-18 years of age with perineal cultures positive for group A Streptococcus (GAS) and reviewed their medical charts. We described epidemiologic features, determined recurrence rates following antibiotic treatment, and performed a case-control study to identify possible risk factors for recurrence in patients treated with amoxicillin.

RESULTS

We found a perineal streptococcal infection rate of 4.6 per 10,000 patient encounters and a recurrence rate in 157 patients with perineal streptococcal infection of 12.4% after amoxicillin. In male patients, the predominant site of involvement was the perianal region (86%), and for female patients, the perivaginal area (62%). Nearly 80% of patients were 2-7 years of age (range 18 days-12.5 years). Perineal streptococcal infection and GAS pharyngitis followed a similar seasonal pattern of occurrence with 65% of perineal streptococcal infection occurring October through March. In patients with perineal streptococcal infection, 95% had a concomitant pharyngeal culture positive for GAS. Best predictive factors for recurrence after amoxicillin were longer duration of symptoms prior to diagnosis and having a sibling with perineal streptococcal infection at some time before or after the initial episode.

CONCLUSIONS

Following treatment with amoxicillin, we found a low recurrence rate of 12.4%. Amoxicillin can be expected to be reliable first-line therapy for perineal streptococcal infection.

[Use of group A streptococcal rapid diagnostic test in extra-pharyngeal infections]

The purpose of this study was to assess the performances of the group A streptococcus (GAS) rapid antigen diagnostic tests (RADTs) in extra-pharyngeal infections. Between October 2009 and June 2014, 368 patients (median age: 48 months) were enrolled. The pathologies involved were : 160 perineal infections (44 %), 69 blistering distal dactylitis (19 %), 55 cervical lymphadenitis (15 %), 31 crusty or bleeding rhinitis (8 %), and 53 other diseases (14 %). The sensitivity of GAS-RADT used was 96 % (95 % CI: 92-99 %), the specificity 81 % (95 % CI: 75- 86 %), the negative predictive value 97 % (CI 95 %: 93-99 %), and the positive predictive value 79 % (95 % CI: 73-85 %). Finally, positive and negative likelihood ratio were 5 (95 % CI: 4-7) and 0.05 (95 % CI: 0.02-0.11) respectively. The GAS-RADTs developed for pharyngitis have comparable performances in these settings and therefore can be used.

[Group A streptococcal perineal infection in children]

Perineal diseases in children are usually caused by group A streptococcus (GAS). If the natural course of untreated cases is not known, it is well known that symptoms do not resolve spontaneously and can persist often for many months, until appropriate diagnosis and effective treatment are instituted. Furthermore, failures and recurrences after penicillin treatment are frequent. From 2009 to 2014, 165 perineal infections (median age: 48 months, extremes: 0.4-139) were enrolled by 15 pediatricians: 4 balanitis, 29 vulvo-vaginal diseases and 132 perianal infections. Painful defecation, anal fissures and macroscopic blood in stools were significantly more frequent in GAS perianal infections than negative GAS infections (p<0.01). The performance of GAS-rapid antigen test compared to the GAS culture was : sensitivity 97 % [CI 95 %: 89-100 %], specificity 76 % [CI 95 %: 66-84 %], negative predictive value 97 % [CI 95 %: 91-100 %], positive predictive value 71 % [CI 95 %: 60-80 %].

Diagnostic accuracy of clinical symptoms and rapid diagnostic test in group A streptococcal perianal infections in children

From 2009 to 2014, we prospectively enrolled 132 children with perianal infections. The presentation of painful defecation, anal fissures, and macroscopic blood in stools was highly suggestive of group A streptococcal perianal infection (probability 83.3%). We found a high sensitivity of a group A streptococcal rapid diagnostic testing (98%) but relatively low specificity (72.8%).

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.

Rapid antigen detection testing in diagnosing group A β-hemolytic streptococcal pharyngitis

Group A beta-hemolytic streptococcus (GABHS) is the most common bacterial cause of acute pharyngitis. Clinical criteria alone are not reliable enough to diagnose GABHS pharyngitis. Microbiological-testing is required for correct diagnosis. Although a throat swab culture remains the gold standard for documenting the presence of GABHS, a significant disadvantage of the culture is the delayed time of 1-2 days to obtain results. Most rapid antigen detection tests can provide results in less than 15 min. Rapid identification and treatment of patients with GABHS pharyngitis can reduce the risk of the spread of disease, may shorten the duration of symptoms, decrease the incidence of suppurative complications, decrease the amount of time lost from school/work, decrease the inappropriate use of antibiotics, reduce patient/parent dissatisfaction and alleviate the need for costly follow-up visits. All rapid antigen detection tests involve extraction of the group-specific carbohydrate antigen from the GABHS cell wall and identification of the antigen by an immunological reaction. There are numerous rapid antigen detection testing methods, namely latex agglutination, enzyme immunoassay, optical immunoassay, chemiluminescent DNA probes and PCR methods. Most of the rapid antigen detection tests that are currently in use have an excellent specificity of greater than 95% and a sensitivity of greater than or equal to 90%. Owing to the high specificity of the rapid antigen detection tests, a positive rapid antigen detection test is accepted as adequate for the diagnosis of GABHS pharyngitis. Conversely, confirmation of a negative antigen detection test with a throat culture result is necessary, unless the physician has ascertained in his/her practice that the sensitivity of the rapid antigen test used is comparable with that of a throat culture.

Pregnancy-related group a streptococcal infections: temporal relationships between bacterial acquisition, infection onset, clinical findings, and outcome

Puerperal sepsis caused by group A Streptococcus (GAS) remains an important cause of maternal and infant mortality worldwide, including countries with modern antibiotic regimens, intensive care measures and infection control practices. To provide insights into the genesis of modern GAS puerperal sepsis, we reviewed the published cases and case series from 1974 to 2009, specifically seeking relationships between the likely source of pathogen acquisition, clinical signs, and symptoms at infection onset and patient outcomes that could provide clues for early diagnosis. Results suggest that the pathogenesis of pregnancy-related GAS infections in modern times is complex and not simply the result of exposure to GAS in the hospital setting. Additional research is needed to further explore the source of GAS, the specific M types involved, and the pathogenesis of these pregnancy-related infections to generate novel preventative and therapeutic strategies.

[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.

Office laboratory procedures, office economics, parenting and parent education, and urinary tract infection

Four areas of pediatric office practice are again reviewed: office laboratory procedures, office economics, parenting and parent education, and urinary tract infection. Screening for celiac disease and the use of rapid antigen testing for extrapharyngeal group A Streptococcus infections are included in office laboratory procedures. Utilization of health care among patients with public insurance, electronic medical records, billing among pediatric residents, and satisfaction surveys are reviewed in office economics. Challenges related to breastfeeding, obesity management and timely immunizations are covered within parenting and parent education. Finally, the use of an augmented urinalysis and a discussion of imaging for first febrile urinary tract infections are included in the area of urinary tract infection.