title: A comparison of methods for detecting adenovirus type 8 keratoconjunctivitis during a nosocomial outbreak in a Neonatal Intensive Care Unit.
abstract: BACKGROUND
  An outbreak of epidemic keratoconjunctivitis (EKC) due to adenovirus (Ad) type 8 and involving 14 members of the hospital staff and 33 neonates admitted to the Neonatal Intensive Care Unit of the local University Hospital occurred between September and December 2000 in Pavia, Italy. The outbreak was preceded by an outbreak of EKC within the community.
  
  
  OBJECTIVE
  To compare the performance of conventional virus isolation on cell cultures, direct detection of Ad antigens in conjunctival cells by a direct fluorescent assay (DFA) and Ad DNA detection in conjunctival swabs by polymerase chain reaction (PCR) for diagnosis of adenoviral conjunctivitis.
  
  
  METHODS
  Of conjunctival swabs collected from 47 patients, all were tested by virus isolation, 43 by direct Ad antigen detection, and 37 by Ad DNA detection. Direct Ad antigen detection was carried out by DFA using a group-specific monoclonal antibody. Detection and subgrouping of Ad DNA by nested PCR was performed using two sets of primers complementary to hexon and fiber genes, respectively.
  
  
  RESULTS
  Ad was detected in 24/47 (51.1%), 21/43 (48.8%), and 23/37 (62.1%) samples by virus isolation, direct antigen detection and PCR, respectively. Overall, 30/47 (63.8%) samples were Ad-positive. Of 37 specimens tested in parallel by all three methods, Ad was detected by at least one of the three techniques in 26/37 (70.3%). All Ad isolates were identified as serotype 8 by neutralization, while all PCR-positive samples were identified as belonging to subgroup D. No other virus was isolated from any conjunctival swab. Time required for test completion was 9.6 (4-20) days for virus isolation, 1-2 h for DFA and 24 h for PCR.
  
  
  CONCLUSIONS
  DFA was a sensitive and rapid assay but results depend on the quality of sample and the expertise of the observer. PCR was the most sensitive assay, although it takes longer to perform and requires dedicated facilities; thus, it could be restricted to DFA-negative samples. Virus isolation is still useful from an epidemiological point of view.
authors.affiliation: Servizio di Virologia, IRCCS Policlinico San Matteo, 27100 Pavia, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Percivalle
authors.forename: Antonella
authors.initials: A
authors.lastname: Sarasini
authors.forename: Maria
authors.initials: M
authors.lastname: Torsellini
authors.forename: Loredana
authors.initials: L
authors.lastname: Bruschi
authors.forename: Elena
authors.initials: E
authors.lastname: Antoniazzi
authors.forename: M
authors.initials: M
authors.lastname: Grazia Revello
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gerna
mesh_terms: D000258:Adenovirus Infections, Human / Q000175:diagnosis / Q000453:epidemiology / Q000821:virology; D000260:Adenoviruses, Human / Q000235:genetics / Q000302:isolation & purification*; D000328:Adult; D003228:Conjunctiva / Q000821:virology; D003236:Conjunctivitis, Viral / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D003428:Cross Infection / Q000175:diagnosis / Q000821:virology; D004196:Disease Outbreaks; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D007637:Keratoconjunctivitis / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D016133:Polymerase Chain Reaction; D013048:Specimen Handling; D014776:Virus Cultivation