title: Incidence of and factors associated with false positives in laboratory diagnosis of norovirus infection by amplification of the RNA-dependent RNA polymerase gene.
abstract: BACKGROUND
  Conventional reverse transcription-polymerase chain reaction (RT-PCR) amplification of the RNA-dependent RNA polymerase (RdRp) gene remains a used method for the rapid detection of norovirus (NV) in clinical laboratories. The incidence of and factors associated with false positives in this assay have not been previously evaluated.
  
  
  RESULTS
  After an NV outbreak caused by the GII.4 Sydney strain in 2012, we reanalysed 250 stool samples positive for NV by RdRp gene detection. True positives were confirmed in 154 (61.6%) samples by successful amplification and sequencing confirmation of the viral protein 1 gene. Of the remaining 96 samples that underwent RT-PCR for the RdRp gene, 34 samples yielded PCR products of the expected length. However, the sequences of the amplicons belonged to the human genome, with 91-97% matched nucleotide sequences, indicating false positives. Multivariate analysis of the clinical features of the patients identified a positive stool culture for bacteria (adjusted odds ratio [aOR] 9.07, 95% adjusted confidence interval [aCI] 2.17-37.92, P = .003) and the use of parenteral antibiotics (aOR 5.55, 95% aCI 1.21-24.73, P = .027) as significant and independent factors associated with false positives.
  
  
  CONCLUSIONS
  Conventional RT-PCR targeting the RdRp gene of NV can lead to false positives in patients with bacterial enterocolitis by incidental amplification of DNA from a human source.
authors.affiliation: College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Fang-Ru
authors.initials: FR
authors.lastname: Lin
authors.affiliation: College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Yu-Hua
authors.initials: YH
authors.lastname: Shen
authors.affiliation: Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Chun-Wan
authors.initials: CW
authors.lastname: Fang
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Shian-Sen
authors.initials: SS
authors.lastname: Shie
authors.affiliation: College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Chung-Guei
authors.initials: CG
authors.lastname: Huang
authors.affiliation: Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Shuan
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Shu-Li
authors.initials: SL
authors.lastname: Yang
authors.affiliation: College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Kuo-Chien
authors.initials: KC
authors.lastname: Tsao
authors.affiliation: College of Medicine, Chang Gung University, Taoyuan, Taiwan; Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Memorial and Children's Hospital, Taoyuan, Taiwan.
authors.forename: Yhu-Chering
authors.initials: YC
authors.lastname: Huang
authors.affiliation: Division of Pediatric Gastroenterology, Department of Pediatrics, Chang Gung Memorial and Children's Hospital, Taoyuan, Taiwan.
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Lai
authors.affiliation: College of Medicine, Chang Gung University, Taoyuan, Taiwan; Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Memorial and Children's Hospital, Taoyuan, Taiwan.
authors.forename: Chih-Jung
authors.initials: CJ
authors.lastname: Chen
mesh_terms: D001483:Base Sequence; D017250:Caliciviridae Infections / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003710:Demography; D004587:Electrophoresis, Agar Gel; D005189:False Positive Reactions; D005260:Female; D005759:Gastroenteritis / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D029322:Norovirus / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012307:Risk Factors
chemical_list: D012324:RNA-Dependent RNA Polymerase