title: Detection of herpes simplex virus and varicella-zoster virus in clinical swabs: frequent inhibition of PCR as determined by internal controls.
abstract: BACKGROUND
  PCR-based detection of microorganisms is widely used for diagnostic purposes. Most routine PCR applications do not control for inhibition of PCR, thus leading to false-negative results.
  
  
  RESULTS
  One hundred eighteen swab samples obtained from skin and mucosa were investigated for the presence of herpes simplex virus (HSV), varicella-zoster virus (VZV), and the control gene betaglobin by internally controlled PCR with purified and unpurified DNA in parallel. With unpurified DNA, inhibition of PCR was detected in 23% of betaglobin PCRs, 25% of VZV PCRs, and 16% of HSV PCRs versus 3% each for purified DNA. Approximately 20% of the samples with positive results for HSV or VZV had negative or inhibited results using unpurified DNA.
  
  
  CONCLUSIONS
  These results indicate that PCR from clinical swab specimens should be performed exclusively with internal controls because the positive control alone cannot exclude PCR inhibition in individual samples. Purification of DNA will decrease, but not exclude, PCR inhibition.
authors.affiliation: Department of Dermatology, University of Ulm, Oberer Eselsberg 40, 89081 Ulm, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Bezold
authors.forename: M
authors.initials: M
authors.lastname: Volkenandt
authors.forename: P
authors.initials: P
authors.lastname: Gottlöber
authors.forename: R U
authors.initials: RU
authors.lastname: Peter
mesh_terms: D003228:Conjunctiva / Q000821:virology; D004279:DNA, Viral / Q000302:isolation & purification; D005188:False Negative Reactions; D006561:Herpes Simplex / Q000175:diagnosis; D006562:Herpes Zoster / Q000175:diagnosis; D014645:Herpesvirus 3, Human / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D009061:Mouth Mucosa / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods*; D011786:Quality Control; D018139:Simplexvirus / Q000235:genetics* / Q000302:isolation & purification*; D012867:Skin / Q000821:virology; D014521:Urethra / Q000821:virology
chemical_list: D004279:DNA, Viral