Suitability of a Throat Culture Method for Evaluation of Group A Streptococcal Antigen Detection Kits

One of the most common conditions encountered in the out-patient setting is acute pharyngitis. Group A Streptococcus (GAS) accounts for 15%-30% of cases of sore throat particularly in children under 15 years old. Rapid antigen testing (RADT) is an alternative diagnostic method to detect GAS pharyngitis. This study was done to evaluate the agreement between RADT whereby BIONEXIA® Strep A Plus (BioMérieux, France) kit was used and throat culture in the diagnosis of GAS pharyngitis in children presented with a sore throat. One hundred and ten children from a primary health care clinic with sore throat were included in this study. All children were evaluated based on McIsaac scoring and throat swab samples were taken for both throat culture and RADT testing. The prevalence of GAS pharyngitis by RADT in this study was 7.3% over one year. A higher incidence of GAS pharyngitis was noted in the school-aged children than the preschool-age children. There was no correlation between cough, lymph node enlargement, and tonsillar enlargement in predicting GAS pharyngitis. The sensitivity and specificity of RADT were 100% and 98%, respectively, when taking throat culture as a gold standard. A good agreement between RADT and throat culture was achieved (k=0.848). McIsaac scoring was noted to have good predictability for GAS pharyngitis with AUC=0.82. In conclusion, the rapid streptococcal antigen detection test showed excellent sensitivity and specificity and detecting GAS from the throat swab samples. Thus, it can be used to aid in the diagnosis of group A Streptococcal pharyngitis and could reduce the overuse of antibiotics. McIsaac score has also proven to be useful as a screening tool for bacterial pharyngitis.

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Modern understanding about the role of group A β -hemolytic streptococcus in acute tonsillitis

Journal Infectology ◽

10.22625/2072-6732-2021-13-4-66-71 ◽

2021 ◽

Vol 13 (4) ◽

pp. 66-71

Author(s):

N. T. Mirzoev ◽

S. N. Sidorchuk ◽

Yu. I. Bulan’kov ◽

K. V. Kas’janenko

Keyword(s):

Predictive Value ◽

Bacterial Culture ◽

Detection Method ◽

Throat Swab ◽

Diagnostic System ◽

Antigen Detection ◽

Acute Tonsillitis ◽

Hemolytic Streptococcus ◽

Streptococcal Antigen ◽

Group A

Objective: assess the modern value of group А β-hemolytic streptococcus in patients with acute tonsillitis and the effectiveness of the rapid streptococcal antigen detection method.Materials and methods: microbial landscape assessment of acute tonsillitis was based on retrospective analysis of 902 bacterial culture results of a throat swab of patients with syndromes of acute tonsillitis treated in the Infectious Diseases Clinic of the Military Medical Academy named after S.M. Kirov during the period of 2019-2020. The effectiveness of the rapid streptococcal antigen detection method in the oropharynx was determined by a prospective study involving 35 patients with acute tonsillitis.Results: in the study, we have found that bacterial culture results of a throat swab, the following were more common: Nesseria species (39 %), Streptococcus viridans (23 %), and Staphylococcus aureus (17 %). The frequency of detection of β-hemolytic streptococcus was 1 %. The rapid diagnostic system «Streptatest» in patients with acute tonsillitis has demonstrated efficiency, under which that sensitivity of test was 80 %, specificity – 90 %, positive predictive value – 57,14 %, negative predictive value – 96,43 %.Conclusions: the frequency of group A β-hemolytic streptococcus in patients with lesion of lymphoid tissues of the oropharynx has declined significantly nowadays. The rapid diagnostic system «Streptatest» is a highly effective medical product that can be used in both hospital and pre-hospital stage.

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Evaluation of the throat culture as a follow-up for an initially negative enzyme immunosorbent assay rapid streptococcal antigen detection test

The Pediatric Infectious Disease Journal ◽

10.1097/00006454-198811000-00004 ◽

1988 ◽

Vol 7 (11) ◽

pp. 765-768 ◽

Cited By ~ 7

Author(s):

SCOT LEWEY ◽

CHRISTOPHER B. WHITE ◽

MICHAEL M. LIEBERMAN ◽

EDMUNDO MORALES

Keyword(s):

Immunosorbent Assay ◽

Antigen Detection ◽

Throat Culture ◽

Streptococcal Antigen

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Group A streptococcal antigen detection in school children

Eastern Mediterranean Health Journal ◽

10.26719/1998.4.2.260 ◽

1998 ◽

Vol 4 (2) ◽

pp. 260-264

Author(s):

H. Nsanze ◽

K. Dawson ◽

A. S. Ameen ◽

N. Mustafa

Keyword(s):

School Children ◽

Group A Streptococcus ◽

Positive Culture ◽

Antigen Detection ◽

Streptococcal Antigen ◽

Group A ◽

Culture Negative

The objective of the study was to determine the correlation between group A streptococcal antigen detected from throat swabs with the culture results. A total of 1457 children had two swabs taken simultaneously, and culture and antigen detection were performed. There was a good correlation between antigen detection and isolation rates. In all, 225 strains of group A streptococcus were isolated;53 [57.6%] were from the 92 children with high antigen positivity, 68 [55.7%] were from the 122 children with medium antigen positivity and 77 [25.4%] were from 303 children with low antigen positivity;only 27 [2.9%] were from the 940 children with no antigen detected. We postulate that those who are antigen-positive, culture-negative carry the organisms in their throats, but they may be missed on culture because of the small number carried

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Rapid Group a Streptococcus Antigen Test (Radt) Usage and Expediency in Diagnosis and Treatment of Pharyngotonsillitis in Family Physician Practice

Sveikatos mokslai ◽

10.5200/sm-hs.2015.031 ◽

2015 ◽

Vol 25 (2) ◽

pp. 54-60

Author(s):

Agnė Augulytė ◽

Povilas Čepanauskas ◽

Kazys Simanauskas

Keyword(s):

Family Physician ◽

Clinical Symptoms ◽

Group A Streptococcus ◽

Antigen Detection ◽

Empiric Antibiotic Therapy ◽

Physician Practice ◽

Antigen Test ◽

Throat Culture ◽

Acute Pharyngitis ◽

Group A

Background. Group A streptococcus (S. pyogenes) is responsi- ble for 5 – 20% of cases of pharyngitis in adults and 15 to 20% of cases in children. Most common diagnostic tests are throat culture and rapid antigen detection testing (RADT). The modified Centor criteria can be used to help physicians decide which patients need no testing, throat culture/rapid antigen detection testing or empiric antibiotic therapy. Objective. Evaluate the rapid group A streptococcus antigen test (RADT) usage and expediency in family physician practice. Goals. To analyze children aged between 3 - 15 who suffers from acute pharyngitis ≥ 3 times per year and have ≥ 3 modified Centor criteria; to evaluate the ease of use of RADT in family phy- sician practice; to identify the correlation between RADT and the clinical symptoms of the acute pharyngitis and between the RADT and the blood test results; to evaluate the importance of RADT in diagnosing the acute pharyngitis and choosing treatment strategy. Methods. The study was accomplished in 2011-2013. 108 children aged between 3 and 15 and who suffers from acute pha- ryngitis > 2 times per year, plus have ≥ 3 modified Centor criteria were investigated. Prospectively all patients were tested by RADT. Also, the prescribed treatment and its effectiveness were analyzed. Statistical facts analysis was performed by using „SPSS 17.0“ and „MS Excel“ programs. Results. Girls suffer more often than boys from acute pha- ryngotonsillitis. The age average of patients was 7,22 ± 3,532. On average, patients appealed to doctor after 2-3 days of illness. RADT was positive in 32 (29.6%) children. Moreover, RADT was more often positive (42%) for children in 7-10 years old group, also for children who had 5 modified Centor criteria (62% of all positive cases). Conclusion. No statistically significant difference was obtained between the clinical symptoms and treatment effectiveness for children with a positive or negative result in RADT. However, all patients with positive RADT and who were taking Phenoxymethyl- penicillin recovered in 10 days. Moreover, obtained data shows that RADT test will facilitate the correct diagnosis and the tactics of selecting the treatment.

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