Atypicals Flashcards
What are the 4 obligate intracellular atypicals?
Chlamydia, Rickettsia, Orientia & Coxiella
Why are the atypicals resistant to cell wall agents and do not stain with Gram stain?
They have little to no peptidoglycan
What is the only atypical that can be grown on agar?
Mycoplasma spp. but grows very very slowly
What are the common clinical presentations of M. pneumoniae infection?
- RTI (upper & lower)
- Atypical pneumonia
What are the infection complications of M. pneumoniae penumonia?
- Erythema multiforme
- Joint pains
- Encephalitis/meningitis
- Haemolytic anaemia
- Myocarditis/pericarditis
How to diagnose M. pneumoniae infection?
- Serology immunoassay - acute & convalescent to compare titers
- PCR
How to treat M. pneumoniae?
Antibiotics - Macrolides, tetracyclines & fluoroquinolones
What group of people are most at risk of M. hominis infection?
Immunocompromised patients
What are the common clinical presentations of M. genitalium infection?
- Uretheritis
- BV
- PID, post-abortion/post-partum infections
- Neonatal infections
What are the 3 diseases caused by C. trachomatis?
- Trachoma
- Lymphogranuloma venereum (LGV)
- Chlamydia - STI + eye infection
What are the complications associated with Trachoma?
- Recurrent infection leads to scarring of eyelids
- Corneal clouding
- Blindness
How is C. trachomatis transmitted?
3 Fs - Fingers, Flies, Fomites
What are the common clinical presentations of Lymphogranuloma venereum (LGV)?
Genital ulcer disease - papule/vesicle/ulcer on genitals
Think of all the inflammations around the male urogenital region
What are the common clinical presentations of Chlamydia in males?
- Urethritis/epididymitis
- Proctitis
- Triad - ACU (reactive Arthritis, Conjunctivitis, Urethritis)
Think of all the inflammations around the urogenital region
What are the common clinical presentations of Chlamydia in females?
- Cervicitis
- PID/salpingitis
- Urethritis, proctitis
- Reactive arthritis
How to diagnose C. trachomatis?
Nucleic Acid Tests
What eye infections can C. trachomatis cause?
- Adult inclusion conjunctivitis
- Ophthalmia neonatorum
What is Ch. psittaci infection associated with?
Birds
What are the common clinical presentations of Ch. pneumoniae infection?
- RTI - upper & lower
- Pneumonia
- Bronchitis
- Sinusitis
What type of cells do Rickettsia spp. & Orientsia spp. typically infect?
Endothelial cells; hence causes rash
How are Rickettsia spp. & Orientia spp. typically transmitted?
Zoonosis via arthopods
What is the disease caused by Coxiella burnetii?
Q fever
What are the clinical presentations of Q fever?
- Mild pneumonia
- PUO, flu-like illness
- Associated with endocarditis
How is C. burnetii diagnosed?
Serology or PCR on heart valves
How to treat Q fever?
Doxycycline + Rifampicin
What is C. burnetii associated with?
Livestock; check for farmhouse/slaughterhouse history in suspected cases
What are the bacteria that cause typhus?
R. prowazekii and R. typhi
What is the bacteria that cause scrub typhus?
Orientia tsutsugamushi
What is R. rickettsii associated with?
Rocky mountain spotted fever
What are the clinical presentations of typhus?
- Fever
- Headache
- Maculopapular rash
What are the 2 complications from typhus?
- SIRS
- Meningoencephalitis
How are typhus and scrub typhus diagnosed?
Triad + serology
How to treat typhus and scrub typhus?
Doxycycline + azithromycin
