Chlamydia & Rickettsia MLAB 2434: Microbiology Keri Brophy-Martinez.
-
Upload
clare-moore -
Category
Documents
-
view
215 -
download
2
Transcript of Chlamydia & Rickettsia MLAB 2434: Microbiology Keri Brophy-Martinez.
Chlamydia & Rickettsia
MLAB 2434: MicrobiologyKeri Brophy-Martinez
General Characteristics
• Obligate intracellular organisms• Can not be cultured on agar plates• Dependant on a host for survival
Chlamydia Characteristics
• Unique growth cycle because they are deficient in independent energy metabolism
• Replication involves elementary body (EB) and reticulate body (RB)– EB’s are infectious and non-
metabolically acitve– RB’s are noninfectious and
metabolically active
Life Cycle of Chlamydia
Chlamydia pneumoniae
• Important respiratory pathogen (acute respiratory disease, pneumonia, and pharyngitis)
• Common (50% of adults have antibodies)
• College age students most susceptible
• Implicated in asthma• Risk factor for Guillain-Barre’ syndrome
Chlamydia pneumoniae (cont’d)
• Reinfection common• Biphasic clinical picture–Prolonged sore throat and
hoarseness, followed by flu-like lower respiratory symptoms–Pneumonia and bronchitis
Chlamydia trachomatis
• Most commonly sexually transmitted bacterial pathogen in U.S.– Only HPV is a more commonly sexually
transmitted disease–Major cause of sterility in U.S.–May be transmitted to newborns during
delivery• Results in conjunctivitis
Chlamydia trachomatis (cont’d)
• Other sites of infection– Trachoma – infection of the conjunctiva,
resulting in scarring and blindness (Mostly in India and Egypt)
– Lymphogranuloma venereum• Infects lymph nodes• STD found in immigrants from the tropics
Chlamydia psittaci
• Causes psittacosis (parrot fever)• Identification based on history of
close contact with birds and serologic evaluation
Laboratory Diagnosis
• If cultured, must be in cells • Direct microscopic examination to find
EB’s– visualized with fluorescein-conjugated
antibodies
• Enzyme immunoassay• Nucleic acid probes with and without
amplification (PCR)• Serologic tests are method of choice for
detection (Four-fold rise in titer)
Rickettsia
• Intracellular, gram negative organism
• Requires host to replicate and survive
• Cause febrile illness through the bite of an arthropod
• Patient often presents with a rash• Posses a cell wall
Rickettsia and Related Organisms
Disease Agent Arthropod Vector
Rocky Mountain spotted fever
Rickettsia rickettsii Wood tick
Rickettsial pox Rickettsia akari House mouse mites
Murine typhus Rickettsia typhii Rat flea
Epidemic typhus Rickettsia prowazekii Human body louse
Scrub typhus Orientia tsutsugamushi Chigger mites
Ehrlichiosis Ehrlichia chaffeenis Lone star tick
Q fever Coxiella burnetti None- spead by inhalation
Laboratory Diagnosis of Rickettsial Disease
• Immunohistochemical detection• Serological tests• PCR
References
• Kiser, K. M., Payne, W. C., & Taff, T. A. (2011). Clinical Laboratory Microbiology: A Practical Approach . Upper Saddle River, NJ: Pearson Education.
• Mahon, C. R., Lehman, D. C., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology (4th ed.). Maryland Heights, MO: Saunders.