The PCR is
the most sensitive of the existing rapid methods to detect microbial pathogens
in clinical specimens. In particular, when specific pathogens that are
difficult to culture in vitro or require a long cultivation period are expected
to be present in specimens, the diagnostic value of PCR is known to be
significant. However, the application of PCR to clinical specimens has many
potential pitfalls due to the susceptibility of PCR to inhibitors,
contamination and experimental conditions. For instance, it is known that the
sensitivity and specificity of a PCR assay is dependent on target genes, primer
sequences, PCR techniques, DNA extraction procedures, and PCR product detection
methods. Even though there are many publications concerning basic protocols of
a PCR assay, including DNA extraction and preparation as well as the
amplification and detection of amplicons, PCR detection of bacteria in clinical
specimens such as cerebrospinal fluid (CSF) has not yet been reviewed. Since a
variety of clinical specimens, such as blood, urine, sputum, CSF and others,
vary in regard to the nature of the content and amount available, careful
design of the PCR assay for each specific specimen before a PCR application is
conducted is essential. In particular, a diagnosis based on detection of a few
bacteria in clinical specimens by using PCR must be carefully evaluated
technically as well as microbiologically. In this regard, current studies
concerning detection of Chlamydia pneumoniae in CSF obtained
from patients with multiple sclerosis (MS) by using PCR provide a good example
for discussion of use of the PCR assay in diagnosis. Because C.
pneumoniae is difficult to culture in vitro, often low numbers of
bacteria may be detected in the CSF of patients with chronic neurological diseases
by PCR. Therefore, in this review general PCR protocols for detection of
bacteria in clinical specimens, as well as a specific example of using PCR for
detection of C. pneumoniae in CSF, will be discussed.
Tidak ada komentar:
Posting Komentar