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Community acquired lobar pneumonia
- Lobar – consolidative:
- Streptococcus pneumoniae
- Haemophilus, Moraxella (Branhamella)
- Legionella
- Staphylococcus aureus
- Atypical – diffuse, interstitial, bronchial, pathy:
- Mycoplasma
- Chlamydia/Chlamydophila
- Viruses
- Legion
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Microbiology – Legionellaceae
- Legionella pneumophila: 15 serogroups based on LPS; 1, 6, 4, 3? Most common
- 40 other legionella species (17 human pathogens)
- Very thing Gram –‘ve bacillus
- Fastidious growth requirements
- Extracellular products – many enzymes cause tissue destruction in course of pathogenesis
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Legionella – Epidemiology
- This one comes from environment
- Water: esp. thermally polluted – plumbing; mud, rivers, streams
- Intracellular in free-living amebae – hitches a ride until it gets to humans
- Biofilms – in nature of in plumbing
- Persistent and adapted
- Sourse of Infection: Environment, NOT person to person
- Mode of Transmission: aerosols, potable H2O – microaspiration
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Legionella – Pathogenesis
- Mechanism: distal airways, alveoli – pulmonary alveolar macrophages – swallow it, but organisms replicate within the macrophage
- Path: Bronchiolitis/alveolitis; exudative, inflammatory, some destruction
- Immunity: Cell-mediated; role of antibody
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Legionella – Clinical
- Lobar or atypical
- Often in immune-compromised patients: transplants, COPD, smokers
- Sometimes in “Normal” patients
- 2-10% of CAP; some nosocomial
- “Pontiac Fever”: mild fever, chills, malaise, headache; no respiratory complaints, often in clusters – common source
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Think Legionella where
- Pneumonia with Gram stain showing WBC but no organisms
- Patient not responding to conventional antibiotics, especially if cultures do not reveal a pathogen
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Legionella – Diagnosis
- Direct fluorescent antibody – BUT it’s serogroup dependent
- Culture on buffered Charcoal Yeast Extract – supplemented and made selective: best for Dx
- Urinary Antigen: BUT serogroup 1 only in U.S., may remain +’ve for months
- Serology: not useful for acute state – it’s unreliable
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Legionella – Rx and Control
- Antibiotics: penicillin doesn’t work!
- Fluoroquinolones, Macrolides
- Water delivery systems: Superheating Hyperchlorination, Ag/Cu ions, ClO2, Aquatic device maintenance
- Aquatic device maintenance
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Mycoplasma - pathogenesis
- Mycoplasma pneumoniae: Prototypical for atypical pneumonia
- Mucosal attachment
- “nondestructive”
- Cilostasis:
- Sloughing:
- Oxidative injury:
- Immunity: lasting? Repeat infections definitely occur
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Mycoplasma – clinical presentation
- Pharyngitis:
- Tracheobronchitis:
- Otitis Media: Bullous
- Pneumonia: generally mild
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Bullous otitis media
Micoplasma – the main cause, choose it on boards
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Mycoplasma: Diagnosis
- Serology: IgM
- Cold Agglutinins: not specific, nos sensitive
- Culture: not warranted
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Mycoplasma Rx:
- Antibiotics: cell wall agents nor active
- Macrolides:
- Tetracyclines (do not use in young children)
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Chlamydia Organisms
- Chlamydia trachomatis
- Clamydophila pneumoniae
- Clamydophila psittaci
- Obligate intracellular parasites
- Extracellular – elementary body
- Replicative – reticulate body
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Chlamydia Antigens and immunity:
- group-specific LPS
- genetic heterogeneity
- serological variability
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Clamydia Treatment:
- Macrolides
- Tetracyclines
- Fluoroquinolones
- Cell wall agents not effective!
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Clamydia Dx
- Culture in cells – but expensive
- Histology – fluids, scrapings, tissue
- Nucleic acid amplification (NAAT) – more widely used
- Serology – not helpful for acute infection
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Clamydia trachomatis
- Epidemiology – contact transmission; reinfection common
- Serotypes A, B, C – Trachoma
- Attachment, cell-cell transfer
- Local infections – persistence and cycling
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Clamydia Tracomatis – Clinical
- Keratoconjuctivitis (trachoma)
- LGV
- Urethritis, cervicitis, PID, epidydymitis
- Pneumonitis in newborns
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Clamydia pneumoniae
- Epidemiology similar to Mycoplasma
- Spread by large droplets/contact
- Disease spectrum: generally mild, slow onset; cough prominent, may persist, airway hyperreactivity
- May have associated sinusitis
- Immunity short-lived, recurrences common
- Link with atherogenesis
- Dx: serology
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Clamydia psittaci
- Psittacosis, ornithosis, parrot fever
- Zoonosis: any bird, bird tissue, droppins, feathers, bird may/may not be ill, excrete more particles when stressed
- Epidemiology: bird contact; often illegally obtained exotics
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Clamydia psittaci Pathogenesis, clinical, Dx
- Pathogenesis: inhalation RES liver, spleen, hematogenous seeding of lungs
- Clinical manifestations: systemic disease, long incubation period (7-14 days); variable illness, but may be severe
- Serology may be helpful in acute disease:
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