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J Clin Microbiol. 2014 Nov;52(11):3884-9. doi: 10.1128/JCM.01489-14. Epub 2014 Aug 20.

Molecular and clinical diagnosis of group A streptococcal pharyngitis in children.

Author information

1
Division of Infectious Diseases, Department of Pediatrics, Children's Hospital Los Angeles and Keck School of Medicine of University of Southern California, Los Angeles, California, USA sfelsenstein@chla.usc.edu.
2
Division of Infectious Diseases, Department of Pediatrics, Children's Hospital Los Angeles and Keck School of Medicine of University of Southern California, Los Angeles, California, USA.
3
Department of Preventive Medicine, Keck School of Medicine of University of Southern California, Los Angeles, California, USA.
4
Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, California, USA.
5
Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles and Keck School of Medicine of University of Southern California, Los Angeles, California, USA.

Abstract

Group A Streptococcus (GAS) pharyngitis is a very common condition causing significant morbidity in children. Accurate diagnosis followed by appropriate antimicrobial therapy is recommended to prevent postinfectious sequelae. Diagnosis of GAS pharyngitis by a rapid antigen detection test (RADT) or culture in the absence of discriminating clinical findings remains challenging. Validation of new sensitive rapid diagnostic tests is therefore a priority. The performance of a loop-mediated isothermal amplification (LAMP) assay (illumigene assay) for the diagnosis of GAS pharyngitis was compared with that of a RADT and standard culture in 361 pediatric throat swab samples. Discrepant results were resolved using an alternate molecular assay. Test results were correlated with clinical presentations in patients positive by either method. The closest estimate of the true prevalence of GAS pharyngitis was 19.7% (71/361 samples). The illumigene assay alone detected 70/71 GAS-positive samples; RADT and culture detected 35/71 and 55/71 samples, respectively. RADT followed by culture confirmation of RADT-negative specimens detected 58/71 cases. The illumigene assay increased identification among children eligible for testing by American College of Physicians (ACP)/American Academy of Family Physicians (AAFP) criteria from 31 to 39 positive cases, five of which were false positives. Analysis of clinical data in GAS-positive patients indicated that a significantly greater proportion of children with McIsaac scores of ≥ 4 tested positive by the illumigene assay versus RADT and culture. Overall, the illumigene assay was much more sensitive and was similarly specific for GAS detection, compared to culture alone, RADT alone, or the ACP/AAFP RADT/culture algorithm. Combining high sensitivity with rapidly available results, the illumigene GAS assay is an appropriate alternative to culture for the laboratory diagnosis of GAS pharyngitis in patients for whom testing is clinically indicated.

PMID:
25143573
PMCID:
PMC4313219
DOI:
10.1128/JCM.01489-14
[Indexed for MEDLINE]
Free PMC Article

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