Chlamydia Flashcards
What are the bacteriological features of Chlamydia?
• Gram negative bacteria • Obligate intracellular pathogens -needs the host’s ATP as an energy source for their own cellular activity – Are very small (0.5 in diameter – I.E. NEED LIVING CELLS TO SURVIVE – IF YOU WANT TO CULTURE THEM NEED LIVING CELLS TOO! – Spreads person to person – Cell wall but not peptidoglycan
What is the unique characters of Chlamydia cell wall?
Chlamydia - The unique cell wall of Chlamydia trachomatis is thought to be one of its virulence factors, as it inhibits phagolysosome fusion in phagocytes. The cell wall contains an outer lipopolysaccharide membrane but lacks peptidoglycan. It instead contains cysteine-rich proteins that are likely the functional equivalent of peptidoglycan. This unique cell wall structure, allows for intracellular division and extracellular survival.
What are the two forms of Chlamydia ?
- Elementary body
2. Reticulate body
What is elementary body of Chlamydia ?
– The infectious particle – is metabolically inactive
– Tough membrane allows it to survive outside host cells
– Taken into the host cell by phagocytosis; a vacuole (the phagosome), derived from the host cell membrane forms around the particle
What is reticulate body of Chlamydia ?
Resemble bacteria in that they: • Possess RNA and DNA • multiply by binary fission • have a rigid cell wall • possess a number of enzymes • are susceptible to some anti-bacterials
Which Chlamydia species are in respiratory tract?
Chlamydia pneumoniae
Chlamydia psittaci
How can Chlamydia pneumoniae spread?
Person to person spread – Inhalation
Outbreaks in nursing homes
What is the clinical presentation of Chlamydia pneumoniae?
– Pneumonia -preceded by pharyngitis – Extra pulmonary manifestations • Meningoencephalitis • Guillain-Barre syndrome • Reactive arthritis • Myocarditis
How can C. psittaci be spread?
(ZOONOSIS) Inhalation of dried infected droppings and/or secretions
– Hx contact with infected birds usually (live or dead!)
– Outbreaks: pet shops, aviaries, veterinary hospital, poultry flocks, turkey and duck processing
What is the clinical presentation of C. psittaci?
- Acute onset of malaise, fever, anorexia, sore throat, photophobia and severe headache
- Atypical pneumonia – lobar changes on CXR
- Complications rare but severe
– Respiratory failure, hepatitis, endocarditis, and encephalitis.
– Infection in pregnancy may be life threatening
Atypical pneumonia due to psittacosis: The family had recently purchased several parrots
What is the diagnosis of C. Pneumoniae and C. Psittaci?
- Nucleic acid amplification testing
- Serology to detect specific IgG
- 4 fold rise in titre
- [cell culture] Obligate intracellular pathogens, i.e. need living cells to survive
What is the treatment of Pneumoniae and C. Psittaci?
• Tetracycline or macrolides
(Doesn’t have peptidoglycan in cell wall – penicillin no use!)
• Mortality as high as 20% in untreated infection, especially in elderly.
Which Chlamydia species are in eyes, respiratory tract, genitals?
Chlamydia trachomatis
What is the clinical presentation of Chlamydia trachomatis in eye?
• Trachoma
– Serovar A, B1, B2, C
• Inclusion conjunctivitis (adults, neonatal conjunctivitis)
– Serovars D to K
What is the clinical presentation of Chlamydia trachomatis in respiratory tract?
• Neonatal pneumonia
– Serovars D to K