| Abstrakt: |
ABSTRACTThe recognition of Moraxella catarrhalisas 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 of M. catarrhalisbacteria 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 the copBouter membrane protein gene, we detected DNA from serial dilutions of M. catarrhaliscells corresponding to 1 to 106cells. Importantly, there was no difference in the amplification efficiency when the same DNA was mixed with DNA from NPSs devoid of M. catarrhalis. The specificity of the reaction was further confirmed by the lack of amplification of DNAs from other Moraxellaspecies, nontypeable Haemophilus influenzae, H. influenzaetype b, Streptococcus pneumoniae, Streptococcus oralis, Streptococcus pyogenes, Bordetella pertussis, Corynebacterium diphtheriae, and various Neisseriaspecies. 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 of M. catarrhalisorganisms detected by real-time PCR correlated with the numbers detected by semiquantitative culture. This real-time PCR assay targeting the copBouter membrane protein gene provided a sensitive and reliable means for the rapid detection and quantification of M. catarrhalisin NPSs; may serve as a tool to study changes in the amounts of M. catarrhalisduring lower respiratory tract infections or following vaccination against S. pneumoniae, H. influenzae, or N. meningitidis; and may be applied to other clinical samples. |
