Pneumonia Flashcards
What is opportunistic pneumonia?
Pneumonia which occurs because of a deficiency in the patient’s immune response
What is a humoral immune deficiency?
Congenital (agammaglobulinemia)
Acquired (chronic lymphocytic leukemia)
What is a cell-mediated immune deficiency?
*HIV (risk of opportunistic infections correlates inversely with CD4 cell count)
Corticosteroid therapy
Lymphoma & treatment, sarcoidosis
Transplantation
Congenital (e.g. severe combined immunodeficiency, di George’s syndrome)
What is a granulocyte immune deficiency?
Number (neutropenia, e.g. post chemotherapy)
Function (usually congenital)
What are some non-specific causes of reduced immunity?
malnutrition, aging, diabetes, alcoholism
How does chronic lymphocytic leukemia impair immune system?
Chronic lymphocytic leukemia (CLL) is associated with functional inability to respond to humoral antigens
What is the most common humoral immunity deficiency?
IgA deficiency, most common, is variable, often asymptomatic or mild
What is IgG deficiency associated with?
May be associated with recurrent otitis, sinus infection, bacterial pulmonary infections, often with encapsulated organisms
What is the management protocol for humoral deficiency?
Immune globulin replacement for IgG deficiency
Early treatment of infection
Antimicrobial prophylaxis
Stem cell transplant in selected circumstances
What causes pneumonia in HiV patients?
M. tuberculosis, *Streptococcus pneumoniae (may occur at any CD4 count, but risk increases with declining CD4)
Pneumocystis jiroveci : Risk largely limited to CD4 count < 200/ml
Miscellaneous: Nocardia, Cryptococcus, Endemic fungi (histoplasmosis, coccidioidomycosis)
Non-infectious: Kaposi’s sarcoma, lymphocytic interstitial pneumonitis
What investigations would be appropriate for HIV patient with respiratory issues?
Sputum (coughed or induced) examination
- Gram stain, C&S
- Special stains: Acid fast, fungal, pneumocystis
Ancillary tests:
Arterial blood gases
LDH (sensitive, not specific in pneumocystis)
CT chest
Bronchoscopy (lavage 95% sensitive in pneumocystis)
Empiric therapy (e.g. for pneumocystis) in selected circumstances, ie when highly typical
Open lung biopsy (rare)
Why does infections occur after a transplant?
Depends on degree of immune suppressive therapy
kidney < heart or liver < lung or intestine < allogeneic stem cell
For transplants, the risk of opportunistic infections causing pneumonia depend on?
the organ transplanted
depends on timing
- first few weeks common bacteria predominate
- 4 weeks to 6 months, CMV
depends on donor and recipient infection status
depends on prophylaxis the patient is taking
How to prevent infections in transplant patients?
Pre-transplant assessment, e.g. CMV status (also of donor).
Pneumocystis prophylaxis with trimethoprim/sulfamethoxazole
Enhanced surveillance and pre-emptive early treatment or prophylaxis (CMV)
What is the risk of infection in neutropenics (ie. acute myelocytic leukemia)?
Risk of infections increases sharply below absolute neutrophil count of 0.5 and with duration of neutropenia
T or F: majority of febrile neutropenia is accompanied by pulmonary infiltrate
F
What is the differential diagnosis of pulmonary infiltrate ?
radiation pneumonitis, drug toxicity, hemorrhage, edema etc. as well as infections
T or F: pulmonary infiltrate with fungal infections have high mortality
T
What organism infect neutropenics?
Early: gram positive & gram negative bacteria
Later, often after prolonged antibiotics: fungi e.g. Aspergillus, less commonly Mucor
Many common agents of community acquired pneumonia, eg Mycoplasma rare in this setting.
What can you consider for treatment in neutropenics?
cytokine therapy—granulocyte stimulating factor to correct neutropenia
How to prevent pneumonia in neutropenics?
Minimize period of neutropenia
Aggressive clinical surveillance
Antibacterial/antifungal prophylaxis depending on specific type of therapy and local epidemiology of opportunistic infections
What is hospital-acquired pneumonia?
Pneumonia acquired after (as a complication of) admission to hospital
What is VAP?
ventilator-associated pressure
What is the pathophysiology of nosocomial pneumonia?
Altered oral flora in sick and hospitalized patients
- -> from GI reflux or upper airway flora or hospital flora
- -> biofilm in Endotracheal tube
- -> Increased risk of/decreased defense against aspiration
What are some risk factors for nosocomial pneumonia?
Neurologic disease or altered consciousness
Age
Functional status
Lung disease, smoking history
Severity of underlying illness
Time (risk is cumulative, but daily risk decreases with time).
Surgery, type of surgery
Position (sitting reduces aspiration risk)
Endotracheal intubation
Antacid therapy
Transmission by HCW’s; failure to handwash
What is the microbial etiologies of nosocomial pneumonia?
Coliforms (E. coli etc.)
Staphylococcus aureus including MRSA
Pseudomonas especially in ICU, after antibiotics
Acinetobacter, Stenotrophomonas
Other (Legionella endemic in some hospitals)
RSV epidemics common in Pediatrics
How to diagnose nosocomial pneumonia?
New radiologic infiltrate & compatible clinical features, e.g. fever, ↑ wbc, hypoxia, ↑ respiratory secretions
What is the treatment/investigations approach for nosocomial pneumonia?
A) Empiric broad spectrum therapy based on “best guess”, local epidemiology and upper airway gram stain and cultures OR
B) Guidance based on respiratory specimen obtained non-invasively with semi-quantitative culture OR
C) “Invasive”diagnosis: bronchoscopy with sheathed brushes or quantitative bronchoalveolar lavage
What is the treatment for nosocomial pneumonia?
Early and mild: “respiratory” fluoroquinolone 3rd generation cephalosporin Late or severe: Piperacillin/tazobactam or carbapenem Plus Vancomycin if evidence or likelihood of MRSA Duration: Usual recommendation: 7 days depending on clinical/radiologic response.
How to prevent nosocomial infections?
Recognize patients @ risk (decreased level of consciousness, altered swallowing, gastro-esophageal reflux)
Minimize aspiration risk
Position, feeding, airway management
Hand washing
Oral care Semirecumbent position Limit antacid use Enteral feeding Hand washing Minimize intubation; use non-invasive ventilation, oral tube preferred to nasal Adequate pressure in ET tube cuff Prevent gastric overdistention Scheduled drainage of condensation from circuits
What is pneumonia?
Inflammation of the lung, usually of infectious etiology
–> Lung parenchyma inflammation/injury +/- filling of alveolar spaces with inflammatory gunk (consolidation)
Can infection to lower tract occur as a result of aspiration?
Yes
What does the development CAP signify?
The development of CAP indicates either a defect in host defenses (local and/or global), exposure to an overwhelming inoculum, or a particularly virulent microorganism
What are symptoms of pneumonia?
Fever Dyspnea Cough Sputum production Pleuritic chest pain Mental status changes
What are signs of pneumonia?
Toxic appearance
Increased temperature
Increased respiratory rate/heart rate [most sensitive sign]
In severe cases respiratory failure & septic shock
Asymmetric movement of chest wall
Increased tactile fremitus
Dullness to percussion
Bronchial breath sounds on auscultation
Crackles, wheezes, egophony, whispering pectoriloquay
+/- signs of a “parapneumonic effusion”
What is essential for the diagnosis of CAP?
CHEST XRAY:
Posterior-anterior and lateral views
If pleural effusion is present, do a lateral decubitus view with the involved side down
BUT CT has higher sensitivity and specificity
T or F: bacterial culture and CBC is always done for CAP
F:
Testing for a microbial diagnosis is usually not performed in outpatients because empiric treatment is almost always successful.HAPs do not need the bloodwork.
What microorganism is most likely associated with CAP?
Bacteria are the most common cause of CAP:
- “Typical” organisms include S. pneumoniae, H. influenzae, S. aureus, Group A strep, M. catarrhalis, anaerobes, and aerobic gram-negative bacteria
- “Atypical” refers to pneumonia caused by Legionella spp, M. pneumoniae, C. pneumoniae, and C. psittaci
What virus is the predominant agent for CAP
Influenza
How to manage pneumonia?
(c) ABC O2 to keep SpO2 > 90%; wean if > 95% IV fluids (early goal directed therapy) Lab work, septic workup (sputum, blood, +/- urine, +/- CSF) PA and Lateral CXR \+/- CT, Bronchoscopy \+/- Isolation precaution
What kind of antibiotic is given for pneumonia?
Initial antibiotic selection for pneumonia is almost always empiric; if/when a likely organism is identified, focus antimicrobials accordingly
- no comorbidity: macrolide OR doxycycline
- comorbidity: fluoroquinolone OR beta-lactam + macrolide
What is Pneumonia Severity Index/Fine Score?
Score to determine if patient should be admitted to the hospital:
Class I/II- Outpatient treatment
Class III- Clinical Judgement
Class IV/V- Hospitalize
Who with CAP should be screened?
Most patients under 50 with CAP should be screened for HIV infection and IgG deficiency
What are some risk factors for pneumonia?
Alterations in the level of consciousness Smoking tobacco Alcohol consumption Malnutrition Being elderly Cystic fibrosis Bronchiectasis Chronic obstructive pulmonary disease (COPD) Previous episode of pneumonia Immunocompromised
What are some bacterial virulence factor for N. meningitidis and S.pneumoniae?
produce proteases that can split secretory IgA
Which organism can shear off cilia [virulence factor]?
Mycoplasma pneumoniae
Whats the virulence factor of Chlamydophila pneumoniae ?
ciliostatic factor
Which organisms are resistant to phagocytosis?
Mycobacterium spp, Nocardia spp, and Legionella spp
What is inlfuenza virus’ virulence?
Influenza virus markedly reduces tracheal mucus velocity within hours of onset of infection and for up to 12 weeks postinfection
What is a missed cause of pneumonia in immunocompromised?
Pneumocystis jirovecii
What is PSI?
Pneumonia Severity Index
Pneumonia Severity Index for Adult CAP estimates mortality for adult patients with community-acquired pneumonia.
