Open AccessQuantitative Detection of Moraxella catarrhalis in Nasopharyngeal Secretions by Real-Time PCR
Author(s) -
Oliver Greiner,
Philip J. Day,
Martin Altwegg,
David Nadal
Publication year - 2003
Publication title -
journal of clinical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.349
H-Index - 255
eISSN - 1070-633X
pISSN - 0095-1137
DOI - 10.1128/jcm.41.4.1386-1390.2003
Subject(s) - moraxella catarrhalis , moraxella (branhamella) catarrhalis , microbiology and biotechnology , haemophilus influenzae , streptococcus pneumoniae , biology , moraxella , neisseria , neisseriaceae , respiratory tract , polymerase chain reaction , streptococcus oralis , pasteurellaceae , bacteria , streptococcus , gene , respiratory system , antibiotics , biochemistry , genetics , anatomy
The recognition ofMoraxella catarrhalis as an important cause of respiratory tract infections has been protracted, mainly because it is a frequent commensal organism of the upper respiratory tract and the diagnostic sensitivity of blood or pleural fluid culture is low. Given that the amount ofM. catarrhalis bacteria in the upper respiratory tract may change during infection, quantification of these bacteria in nasopharyngeal secretions (NPSs) by real-time PCR may offer a suitable diagnostic approach. Using primers and a fluorescent probe specific for thecopB outer membrane protein gene, we detected DNA from serial dilutions ofM. catarrhalis cells corresponding to 1 to 106 cells. Importantly, there was no difference in the amplification efficiency when the same DNA was mixed with DNA from NPSs devoid ofM. catarrhalis . The specificity of the reaction was further confirmed by the lack of amplification of DNAs from otherMoraxella species, nontypeableHaemophilus influenzae ,H. influenzae type b,Streptococcus pneumoniae ,Streptococcus oralis ,Streptococcus pyogenes ,Bordetella pertussis ,Corynebacterium diphtheriae , and variousNeisseria species. The assay applied to NPSs from 184 patients with respiratory tract infections performed with a sensitivity of 100% and a specificity of up to 98% compared to the culture results. The numbers ofM. catarrhalis organisms detected by real-time PCR correlated with the numbers detected by semiquantitative culture. This real-time PCR assay targeting thecopB outer membrane protein gene provided a sensitive and reliable means for the rapid detection and quantification ofM. catarrhalis in NPSs; may serve as a tool to study changes in the amounts ofM. catarrhalis during lower respiratory tract infections or following vaccination againstS. pneumoniae ,H. influenzae , orN. meningitidis ; and may be applied to other clinical samples.