title: Comparative evaluation of culture and PCR for the detection and determination of persistence of bacterial strains and DNAs in the Chinchilla laniger model of otitis media.
abstract: This study was designed to determine the persistence of culturable bacteria versus DNA in the presence of a middle ear effusion in a chinchilla model of otitis media. Cohorts of animals were either infected with an ampicillin-resistant Haemophilus influenzae strain or injected with a tripartite inoculum consisting of freeze-thawed Streptococcus pneumoniae; pasteurized Moraxella catarrhalis; and DNA from H influenzae. The H influenzae-infected animals displayed culture positivity and polymerase chain reaction positivity through day 35. In the chinchillas infected with the low-copy number inocula of S pneumoniae, DNA was not detectable after day 1 from the co-inoculated pasteurized M catarrhalis bacteria or the purified H influenzae DNA; however, amplifiable DNA from the live low-copy number bacteria persisted through day 21 even though they were not culture-positive past day 3. These results demonstrate that DNA, and DNA from intact but nonviable bacteria, does not persist in an amplifiable form for more than a day in the presence of an effusion; however, live bacteria, while not culturable, persist in a viable state for weeks.
authors.affiliation: Department of Pathology, School of Medicine, University of Pittsburgh Medical Center, Pennsylvania, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Aul
authors.forename: K W
authors.initials: KW
authors.lastname: Anderson
authors.forename: R M
authors.initials: RM
authors.lastname: Wadowsky
authors.forename: W J
authors.initials: WJ
authors.lastname: Doyle
authors.forename: L A
authors.initials: LA
authors.lastname: Kingsley
authors.forename: J C
authors.initials: JC
authors.lastname: Post
authors.forename: G D
authors.initials: GD
authors.lastname: Ehrlich
mesh_terms: D000668:Ampicillin Resistance; D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D002682:Chinchilla; D004269:DNA, Bacterial / Q000032:analysis*; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D001936:Moraxella catarrhalis / Q000235:genetics / Q000302:isolation & purification; D016870:Neisseriaceae Infections / Q000382:microbiology; D010034:Otitis Media with Effusion / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000382:microbiology; D016133:Polymerase Chain Reaction; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial