ABSTRACT
We compared three commercially available group A Streptococcus (GAS) nucleic acid amplification tests, the Quidel Solana GAS assay, the Luminex Aries Group A Strep assay and the Focus Diagnostics Simplexa Group A Strep Direct assay, with GAS bacterial culture. A true positive result was defined as one positive by culture or positive by ≥2/3 molecular methods. Two hundred eighty-seven throat swabs (207 children, 80 adults) were collected. The sensitivity of culture was 84.8% (95% CI 77.7-90.3%) with a specificity of 100% (95% CI 97.5-100%). The Solana assay sensitivity was 94.2% (95% CI 88.9-97.5%) with a specificity of 98.7% (95% CI 95.2-99.8%). Simplexa assay sensitivity was 99.3% (95% CI 96.0-99.9%) with a specificity of 95.3% (95% CI 90.6-98.1%). Aries assay sensitivity was 96.4% (95% CI 91.8-98.8%) with a specificity of 98.0% (95% CI 94.2-99.6%). In summary, all the molecular methods evaluated showed high sensitivity and specificity and were more sensitive than culture.
Subject(s)
Bacteriological Techniques/methods , Molecular Diagnostic Techniques/methods , Pharynx/microbiology , Streptococcal Infections/diagnosis , Streptococcus pyogenes/isolation & purification , Adult , Child , Humans , Nucleic Acid Amplification Techniques , Sensitivity and Specificity , Streptococcal Infections/microbiologyABSTRACT
BACKGROUND: Molecular methods enable more rapid and sensitive detection of herpes simplex virus (HSV) than viral culture. OBJECTIVE: Three commercial molecular methods, all of which detect both HSV-1 and HSV-2, were compared to viral culture for the detection of HSV from swab specimens. STUDY DESIGN: Pediatric and adult patient viral swab specimens were cultured for HSV. Residual swab fluid was frozen at -80 °C until tested with the 3 molecular methods: the Quidel Solana HSV 1 + 2/VZV Assay, the Focus Diagnostics Simplexa HSV 1 & 2 Direct Assay and the Luminex Aries HSV 1&2 Assay. A true positive was defined as positive by culture or positive by ≥ 2/3 molecular methods. RESULTS: 177 specimens were studied. The sensitivity of culture was 81.3% (61/75, 95% CI 70.7-89.4%) and specificity was 100% (102/102, 95% CI 96.4-100%). The sensitivities of both the Solana and Simplexa were 100% (75/75, 95% CI 95.2-100%) and specificities were also both 100% (102/102, 95% CI 96.4-100%). The Aries had a sensitivity of 98.7% (74/75, 95% CI 92.8-99.97%) and specificity 99.0% (101/102, 95% CI 94.7-99.98%). All three molecular methods were significantly more sensitive than culture (p ≤ 0.0005 for Solana and Simplexa and p ≤ 0.0012 for Aries). CONCLUSION: All the molecular methods studied provided a significantly higher sensitivity than culture. In addition, the molecular methods took 1-2 hours to perform compared to a mean of 2.1 days for culture results. Use of any of the three molecular methods could lead to improved patient care.
Subject(s)
Herpesvirus 1, Human/isolation & purification , Herpesvirus 2, Human/isolation & purification , Molecular Diagnostic Techniques/instrumentation , Molecular Diagnostic Techniques/standards , Adolescent , Adult , Child , Child, Preschool , Female , Humans , Male , Nucleic Acid Amplification Techniques/instrumentation , Nucleic Acid Amplification Techniques/standards , Reagent Kits, Diagnostic/standards , Sensitivity and Specificity , Time Factors , Virology/methods , Virology/standardsABSTRACT
OBJECTIVE: Molecular methods to detect diarrheal pathogens are increasingly being used in place of conventional methods. We compared a new multiplex real-time PCR assay for detection of both bacterial and viral gastroenteritis agents, the Allplex™ Gastrointestinal Panel Assays (AGPA), to conventional methods (stool culture for bacterial pathogens and electron microscopy (EM) for viral pathogens). RESULTS: Gastrointestinal viruses, in particular norovirus genogroup II viruses, were detected by the AGPA in a high number of specimens that were negative by EM. For bacterial pathogens, the AGPA was able to detect the organisms grown in culture with high sensitivity and additionally detected several types of E. coli, such as enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), and non-O157 Shiga toxin-producing E. coli (STEC), that could not be detected with conventional culture methods. Overall, the AGPA had a > 2-fold higher detection rate than the conventional methods, with 24/135 (17.8%) samples positive by conventional methods and 60/135 (44.4%) by AGPA. Thus, diarrhea pathogen detection rates increased substantially with the use of the AGPA as compared to conventional methods.
