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- Histoplasmos -- dimorphic fungi of the Ohio & Mississippi river valleys
- necrotizing granulomatous inflammation (like TB)
- infection may follow outdoor dust exposure
- Also present in bats and batcaves
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- Coccidiodomycosis immitus
- In desert SW (So. Utah)
- Cough, fever
- Granulomatous infection
- Can present as solitary lung nodule
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- Aspergillus (on R Aspergillus GMS stain)
- 3 forms: invasive in an immunocompromised host; growth in cavity (fungus ball in pre-existing cavity); Allergic form (bronchopulmonary aspergillosis)
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- Pneumocystis jiroveci pneumonia (PCP)Most common in immunocompromised Pt's (AIDS)
- HIV Pt's now given prophylaxis to avoid PCP
- Presents w/ slowly progressive nonproductive cough
- Usually not in sputum, need BAL to diagnose
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Influenza, parainfluenza, cytomegalovirus, hantavirus cause what?
- Viral Pneumonias (clayton)
- cough w/ little or no sputum
- Often no inclusions or specific histologic cultures. Culture is difficult.
- Serologic titers, PCR, antigen tests & DFA for influenza
- (late bacterial superinfection is a problem)
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Influenza pneumonia -- most common viral pneumonia in adults, Resp. & alveolar epithelium are both infected and injured.
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RSV-- infants and young children (reinfection is common)
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Herpes simlex pneumonia -- areas of necrosis are common, usually in compromised hosts.
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CMV (cytomegalovirus)
Huge cells, big nuclear inclusions, compromised hosts, a type of herpes virus.
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Smudge cells => adenovirus
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How can you make a correct diagnosis?
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Name the dz
Poorly staining gram negative rods, fastidious and intracellular oraganisms.
Invades parenchymal lung cells, and phagocytes and destroys them.
Produces toxin that blocks phagocytic killing
Fatal in 15-50%; presents w/ fever, headache, cough, pleuritic chest pain, N/V, mental status changes, hepatic dysfunction.
Legionella
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Name the illness
Caused by legionella
dry cough (50%)
No pregression full recovery, usually in young/healthy adults
Pontiac fever (much less severe illness than legionnaires dz caused by legionella)
Legionella can also cause isolated infections, meningitis, endocarditis, soft tissue infections.
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What is it?
- Legionella (top 2 gram stain, LL = charcoal ager, LR - DFA)
- Consider it in any severe pneumonia
- CXR (often see cavities)
- Gram stain of sputum (PMNs, no organisms)
- Urinary antigen => direct detection
- Serology takes up to 6 weeks (not helpful)
- PCR => $$
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What could be a possible cuase of a pneumonia that follows aspiration, is an insidious dz with an altered mental state, only infiltrates the lower lobe, and progresses slowly?
Anaerobic bacteria (cannot multiply in the presence of oxygen)
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This organism is gram + but stains poorly (UR is Acid Fast); grows slowly; causes TB; primarily pulmonary dz, but can infect other locations, granulomatous responses, is a major health problem world wide, person-person transmission (resp. droplet).
Mycobacteria
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Mycobacterium tuberculosis
attaches to alveolar cells, ingested by macrophages, disseminates via lymphatics and circulation, may be controlled and cured. (can be quiescent and then relapse)
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Name the illness:
Ordinary resp. flu-like Sx; lower lobe pneumonia, spread from hilum to lymph, controlled in 6-8 weeks, organism lives in lymph tissue for years.
Primary tuberculosis
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Reactivation TB
- most likely within 2 years of initial infection (although can occur at any time)
- Predispositions: diabetes, alcoholism, malnutrition, immunodeficiency
- Progresses slowly, and usually involves lung apices,
- 80-90% pulmonary
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Fever, cough, hemoptysis, night sweats, weight loss, fatigue are classic symptoms of what dz?
TB
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How should you diagnise a Pt w/ TB?
- clinical suspicion
- exposure
- prior positive PPD (may or may not help)
- acid fast stain and culture
- amplification tests
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How can one prevent TB?
- Recognize clinical cases and isolate them, then treat them appropriately tracing and testing contacts.
- Skin testing to identify at risk population and health care workers
- Treatment of Pt's with + PPDs.
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M kansasii
M avium
M fortuitum and chelonei
M leprae
M scrofulaceum
M marinum
These are other mycobacteria; no person-person spread.
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Differentiate between AFB smears, AFB cultures and amplification.
- AFB smears: rapid test for TB that correlates w/ contagiousness (60% sensitive)
- AFB culture: gold standard for dx, but takes 10-28 days for + (90-95% sensitive)
- Amplification: improving rapid method, excellent to confirm an AFB, but not as good for detection. (60-90% sensitive)
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When would a TB test not remain positive in a Pt who previously had a + result?
active dz, immunosuppression, other serious dz, malnutrition, aging
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TB skin tests
- become + in 2-4 wks, use 5 TU strength (3 strengths), interpretations vary by pop., most helpful for screening but can be used to dx.
- Sensitivity = 70%
- other mycobacteria can lead to false +'s, but always assume a + is real until proven otherwise.
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Name the organism based on the following pathogenesis
organism inhaled, causes pneumonitis, T-cell response and granuloma formation, enters R-E system, May disseminate like TB, May reactivate like TB
Clinical Manifestations: most likely asymptomatic, or flu-like symptoms, primary pulmonary dz, reactivates upon immunosuppression (fever, dz of CNS, skin, mucous membranes, adrenals, or lung)
Histoplasma (miliary dz caused by histoplasma looks similar but has many small nodules)
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- How can you confirm suspected Histoplasma?
- Direct detection in tissue biopsy, culture, antigen test of urine, antibody tests, skin tests.
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the following organism is similar to histoplasma (only it is more likely to involve skin and gu tract)
it is prevelant in the eastern US along the Appalachain Mtns.
Blastomyces dermatitidis
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The organism is similar to Histo and Blasto, but usually found in the SW (including So. Utah)
Easily acquired -- but usually confined to lung
Dissemination to: skin, bone, meninges, adrenals, nodes, liver
Spherules, culture is dangerous, IgMand IgG both detectable via serology
Coccidioides immitis
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Used to be considered a parasite, but no recognized as a fungus,
Life cycle: troph, precyst, cyst
Cell wall different than other fungi (no glucan or N-acetulclucosamine)
Most common opportunistic infection associated w/ HIV
Clinical Manifestations: progressive diffuse pneumonia, tachyapnea, dyspnea w/ cyanosis and hypoxia; slow onset w/ low grade fever; diffuse infiltrate on CXR; disseminates to lymph nodes, bone marrow, spleen, liver, thyroid, GI tract, kidneys
Diagnosed by induced sputum or bronchoscopy; look for organism: methamine silver, DFA, other stains.
Pneumocystis
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How would you treat a Pt w/ pneumocystis?
- Sulfamethoxazole trimethoprim,
- All HIV Pt's w/ CD4<200 are treated w/ bactrim or dapsone to prevent infection.
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Air space opacity
Think bacterial
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Interstitial opacities (look more like a dirty than cloud-like)
Think virus or virus-like (large arrows point to fibrous exudate, small arrows point to interstitial thickening due to fibroblastic proliferation)
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Apical airspace opacity (especially if cavitating)
Think reactivation TB
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Multifocal opacities (especially lower lung zones and right > left)
Think aspiration (pneumonia)
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Numerous small nodules
Think miliary TB (blood bourne)
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Ill-defined nodules and cavities in a neutropenic patient
Think fungus/aspergillus
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Multiple ill-defined nodules and cavities peripherally in a Pt with infective endocarditis who is very ill
Think septic emboli (often staph. aureus)
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Patchy, hazy, ground glass opacities in an AIDS patient
Think PcP
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Older Pt with pneumonia -- get follow up in about 6 weeks
Look for complete clearing to exclude underlying process, especially malignancy
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Diaphragm, external intercostals, scalene, sternocleidomastoid, internal intercostals
muscles of respiration
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Candida albicans, neisseria spp, viridans streptococci, moraxella, peptostreptococcus
normal flora of the oropharynx
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