Atypical Pneumonia Flashcards
- Discuss the general aspects of pneumonia pathogenesis.
pneumonia causes alveoli to fill with fluid so there is consolidation, it can be caused by chemical or physical injury, most commonly infectious disease
colonization of URT followed by dysfunction of the mucociliary escalator;
in the case of aspiration, oral flora is transferred to the lungs because cough reflex is diminished;
antigen is inhaled directly into the LRT or derived from hematologic seeding (S. aureus and endocarditis)
- Explain the general properties and the life cycle of Chlamydia and Chlamydophila species.
both are obligatory intracellular Gram neg. bacteria that form inclusions (cell takes 2-3 days)
EB is passively engulfed and is not degraded in phagosome
EB reorganization into RB that divide using host phosphate compounds
when RB are plentiful they condense into EBs are extruded when the cell bursts
- Compare and contrast the properties of the elementary body and the reticulate body found in Chlamydia and Chlamydophila species.
EB are small dense particles that are infectious, non-replicating particles
RB are large, non-infectious particles that replicate by binary fission
- Explain the disease complications associated with infections cause by Chlamydia and Chlamydophila species.
3 important human species: Chlamydia trachomatis, pneumoniae and psittaci
Trachomatis: sexually transmitted infection, eye infection
Pneumoniae: CAP (10% of cases), bronchitis, sinusitis, otitis media, possibly atherosclerosis
Psittaci: severe pneumonia, associated with contact with parrots or cockatiels who do not appear ill
- Discuss the general properties attributable to Mycoplasma.
smaller known genome of a free-living organism, strict aerobe but the other species are facultative organisms (mollicutes), smaller org. capable of reproducing in broth and on agar media– can pass through filters used to remove most bacteria
lack peptidoglycan, produce both hydrogen peroxide and superoxide, inhibit host cell catalase; P1 adhesion can cause cessation in cilia motion
- Compare and contrast acute pneumonia with Pontiac fever caused by L. pneumophilia.
Pontiac fever is flu like illness that lasts 2-5 days, presents without respiratory symptoms caused by a hypersensitivity reaction to Legionella, has a very high attack rate unlike acute pneumonia
- Explain how disease caused Legionella species are diagnosed.
sputum typically reveal neutrophils with no microorganism, organisms grow in culture and visible with silver stain used (must be grown in BCYE media and can take up to 14 days)
urine Legionella antigen test is widely available (only detects serogroup 1)
serology can also be used to dx. L. Pneumophila if a four fold increase in antibody titer is seen in paired serum
What are strategies to contain Legionella?
periodic superheating or use of copper-silver ionization, organisms can tolerate high levels of chlorine; monitoring water sources in high risk setting is important for containment
What is pneumonitis?
conditions characterized by inflammation of the parenchyma of the lung
- What is the classic manifestation of pneumonia as well as clinical findings?
cough, fever, chills and SOB; cough may be dry or productive, pleuritic chest pain is common, anorexia and headache
ronchi, rales over affected area, ego phony or resonance suggest consolidation (none are terribly specific)
can be classified by clinical context, pathologic findings, microbiologic characteristics or radiologic appearance
What is atypical pneumonia?
clinical pneumonia without organism seen on sputum Gram stain, includes 3 of the 5 most common bacteria for CAP: Legionella pneumophila, Mycoplasma pneumoniae, Chlamydophila pneumoniae
What are the basic treatments (3) for community acquired pneumonia?
doxycycline, macrolide or fluoroquinolone
- Explain the long-term complications associated with infections cause by Chlamydia and Chlamydophila species.
Trachoma: blinds
PID: infertility, chronic pain, ectopic pregnancy
Urethritis: reactive arthritis
Cervitis: cancer of cervix (serotype G)
- Discuss the general properties attributable to Legionella species.
slender, motile, aerobic rods that do not have a capsule and do not form spores (Gram-neg rods)
considered difficult to grow, most important strain is Legionella pneumophila serogroup 1 (80% infections)
associated with hot tubs, shower heads, AC etc. (microbes aid in the growth and distribution of Legionella)
transmission occurs via inhalation of droplets and dx. is more severe in patients who have impaired respiratory function (no person to person transmission)
What disease are caused by mycoplasma species?
Mycoplasm pneumoniae: CAP, walking pneumonia (no seasonality) spread person to person resulting in dry cough, dyspnea and fever, usually mild and best dx. blood antigens called cold agglutinins
trachobronchitis, sinusitis and pharyngitis, rash, urticaria, erythmea multiform and Stevens-Johnson syndrome, meningitis, meningoencephalitis, cerebellitis, acute psychosis and Guillain Barre syndrome, pancreatits, carditis, pericarditis, bullous laryngitis, hemolytic anemia
M. Hominis: tubo-ovarian abscesses, salphingitis, PID
M. genitalium: non specific uretritis and PID
