Microbiology Week 3 Exam 3

Terms in this set (174)

More Chlamydiae present in specimen from symptomatic infections: Obligate, intracellular nature of Chamydia requires a need to obtain specimen from infected site
A specimen of pus or exudate is inadequate.
Heat sensitivity can destroy specimen
Cytology: Examine Giemsa-stained cell scrapings
for presence of inclusions. Problem: Insensitive and not recommended
Culture: Most specific method, but only ~70% sensitive. Specimens are added to cultures of susceptible cells and the infected cells are examined for the presence of iodine-staining inclusion bodies or fluorescent-staining of MOMP or LPS.
Problem: Detection compromised in certain specimens or loss of viability during specimen manipulation/transport
Antigen Detection: Direct immunofluorescence, or ELISA Use antibodies to detect LPS or MOMP
Problem: Asymptomatic patients and male urethral
samples tend to have low bacterial loads.
Antigenic determinants (LPS) may be shared with other bacteria
Serology : Limited value, do not distinguish between current or past infection, IgM levels not useful because patients often do not produce these antibodies. Exceptions: Infants with chlamydial pneumonia LGV patients-- produce a vigorous antibody response
Nucleic Acid Probes (Molecular probes):
Non-amplified: Measure presence of species-specific 16S RNA Rapid and relatively inexpensive
Problem with sensitivity (low bacterial load)
Amplification techniques (NAAT): i.e. PCR
Considered the test of choice for laboratory diagnosis
90-98% sensitive and very specific if properly monitored
Problems include presence of inhibitors in specimens and cross-contamination of samples.
Tests are available to detect Chlamydia in samples from endocervical swabs, urethral swabs, urine.