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Which of the following is the strongest predisposing factor for pneumonia?
What percentage of cases of pneumonia caused by S.aureus range from?
20% to 30%
Mortality rate for pneumonia can be as high as 50%.
True
What are the two categories of pneumonia based on acquisition?
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Which of the following is a common cause of hospital-acquired pneumonia?
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The risk for developing pneumonia in the hospital increases by ________ times after a patient is intubated.
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What can exacerbate the risk of pneumonia in hospitalized patients?
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Patients with chronic illnesses are less likely to experience severe manifestations of pneumonia.
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What symptoms are indicative of a more severe clinical presentation in pneumonia when TNF-α and interleukins are released?
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Which of the following symptoms is NOT typically associated with pneumonia?
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What test is recommended for hospitalized children suspected of having pneumonia?
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What is a characteristic of urinary antigen tests for detecting S.pneumoniae and L.pneumophila in adults with severe CAP?
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How soon can urinary antigen tests detect pathogen antigens after initiation of antibiotic therapy for S.pneumoniae?
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What is the primary purpose of continually monitoring a patient's clinical status and diagnostic data?
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Which of the following is NOT a criterion used in the CURB-65 assessment?
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What is indicated for hospitalized patients with severe community-acquired pneumonia regarding MRSA?
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What might occur if appropriate therapies are not narrowed or adjusted after evaluating infection status?
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Among patients at risk of aspiration, which pathogen is particularly important to consider?
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What is a defining characteristic of community-acquired pneumonia (CAP)?
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Which group of individuals is more likely to have inadequate respiratory defense mechanisms?
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What effect can lung infections have on the alveolar macrophages?
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How does alteration of the lung microbiome relate to pneumonia?
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What is a common feature of multidrug-resistant pathogens in pneumonia?
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Which factor does NOT contribute to the local host defenses of the lower respiratory tract?
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What can lead to a secondary bacterial pneumonia following a lung infection?
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What is a characteristic of atypical pneumonia caused by Mycoplasma pneumoniae?
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Which of the following best describes the respiratory host defenses?
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Which statement about aspiration is correct?
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What is the role of mucociliary clearance in respiratory defense mechanisms?
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Which of the following correctly describes the effect of mucous in the respiratory tract?
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What is the primary role of cilia in the lower respiratory tract?
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Which antibiotic is preferred for treating methicillin-susceptible Staphylococcus aureus (MSSA) infections in community-acquired pneumonia?
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What additional antibiotic coverage should patients in a hospital with an MRSA prevalence of 20% or greater receive?
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Which antibiotic is categorized as an alternative for methicillin-susceptible strains but is less preferred for pneumonia treatment?
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In patients at risk for multi-drug resistant (MDR) HAP, what type of coverage should they also receive?
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What is the most common gram-negative cause of pneumonia?
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Which of the following is an acceptable treatment alternative for MRSA pneumonia?
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What type of antibiotic regimens should empiric treatment for hospital-acquired pneumonia include?
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What is the significance of a high MIC value in penicillin-intermediate strains when considering amoxicillin treatment?
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Study Notes
Pneumonia
- Inflammation of one or both lungs that affects the air sacs, or alveoli, which fill with fluid or pus.
- Leading infectious cause of death in children and adults in the United States.
- Affects people of all ages, with the most severe clinical manifestations in the very young, elderly, and chronically ill.
- Occurs throughout the year, with seasonal variations in the relative incidence of disease.
- Caused by various viral and bacterial pathogens.
- Classified as either community-acquired or hospital-acquired.
Hospital-acquired Pneumonia (HAP)
- Occurs after 48 or more hours of endotracheal intubation.
- Risk of developing HAP increases by 6 to 21 times after intubation.
- Strongest predisposing factor is mechanical ventilation or intubation.
- Often caused by gram-negative aerobic bacilli or Staphylococcus aureus.
- Patients with longer hospital admissions or IV antibiotic use within 90 days preceding HAP are more likely to have multidrug-resistant (MDR) organisms.
- Mortality rate can be as high as 50%.
Ventilator-associated Pneumonia (VAP)
- A subtype of hospital-acquired pneumonia.
- Exacerbated by acid-suppressing drugs like H2-receptor blocking agents and proton pump inhibitors.
- More commonly caused by Staphylococcus aureus (20-30%) with a higher incidence of multidrug resistance.
Pathogenesis
- In healthy individuals, the respiratory host defenses effectively remove respiratory pathogens before infection occurs.
- These defense mechanisms include both innate and adaptive immunity pathways.
- Immunocompromised individuals lack robust defense mechanisms and are more susceptible to pneumonia, such as those with cystic fibrosis or prolonged neutropenia.
- Lung infections can suppress antibacterial activity by impairing alveolar macrophage function and mucociliary clearance, making the lung more vulnerable to secondary bacterial pneumonia.
- Any alteration of the normal lung microbiome by infection or disease can evolve to pneumonia requiring antimicrobial treatment.
Community Acquired Pneumonia (CAP)
- Majority of cases caused by Streptococcus pneumoniae (20-30%)
- Community-acquired or hospital acquired
- Can be caused by bacteria, atypical organisms, or viruses
Pathogenesis
- Respiratory defenses include both innate and adaptive immunity
- Defenses are preserved in healthy individuals
- Immunocompromised people have weakened defenses (e.g., cystic fibrosis, prolonged neutropenia)
- Lung infections can suppress antibacterial activity by:
- Impairing alveolar macrophage function
- Decreasing mucociliary clearance
Pathophysiology
- CAP: Onset is outside the hospital or within 48 hours of hospital admission
- Local host defenses of the lower respiratory tract:
- Mucus lining
- Cilia
- Antibodies (IgA, IgM, IgG)
- Complement
- Alveolar macrophages
- Aspiration can lead to aspiration pneumonia or chemical (acid) pneumonitis
- Systemic release of TNF-α and interleukins (ILs)-1 and -6 can lead to severe symptoms:
- Hypotension
- Organ dysfunction
- Septic or septic-shock
Clinical Presentation
- Fever, chills, malaise (constitutional symptoms)
- Cough, increased sputum production, dyspnea (respiratory symptoms)
- Abrupt onset
- Rust-colored sputum or hemoptysis
- Pleuritic chest pain
- Dyspnea
Diagnostics
- Sputum Gram stain and culture recommended for hospitalized children who can produce a sample
- Blood cultures recommended for moderate/severe CAP
- Urinary antigen tests available for S. pneumoniae and L. pneumophila, recommended in adults with severe CAP
- High specificity (90-99%) but lower sensitivity (50-80%)
- Can detect pathogen antigen days to weeks after starting antibiotic therapy
Treatment
- Continued monitoring of patient's clinical status and diagnostic data
- Decision to continue, narrow, alter, or discontinue therapy based on data
- CURB-65 and CRB-65 are commonly used severity assessments
Risk Factors for CAP
- Previous hospitalization within the past month
- Use of broad-spectrum antibiotics in the past 7 days
- Severe underlying bronchopulmonary disease
- Malnutrition
- Chronic use of steroids >15 mg/day for at least 2 weeks
Empiric Therapy
- Based on likely pathogens
- No P. aeruginosa risk:
- Ceftriaxone 2g IV q24h OR Ertapenem 1g IV q24h PLUS Azithromycin 500mg IV daily OR Levofloxacin 750mg IV daily
- Risk for P. aeruginosa:
- Piperacillin-tazobactam OR Cefepime PLUS Azithromycin 500mg IV daily OR Levofloxacin 750mg IV daily
- High-dose amoxicillin (3 g/day) may be used for penicillin-intermediate strains (MIC = 4 mg/L)
MRSA Coverage for Hospitalized Patients with Severe CAP
- Consider MRSA coverage in the following cases:
- Requirement for intensive care unit (ICU) admission
- MRSA prevalence of 20% or greater in the hospital or unit
Specific MRSA Regimen
- Vancomycin or Linezolid are the preferred treatments
- Alternatives include:
- Quinupristin-dalfopristin
- Ceftaroline
- Sulfamethoxazole-trimethoprim
- Clindamycin
Gram-Negative Pathogens
- Haemophilus influenzae is the most common gram-negative cause of HAP.
Hospital Acquired Pneumonia (HAP)
- Most HAP cases are caused by gram-negative bacilli:
- P. aeruginosa
- Enterobacteriaceae
- S. aureus
- Empiric regimens should include at least one antibiotic with coverage against these pathogens:
- An antipseudomonal, antistaphylococcal β-lactam (e.g., piperacillin/tazobactam or cefepime)
- An antipseudomonal, antistaphylococcal fluoroquinolone (e.g., levofloxacin)
- Patients with MDR HAP risk factors (e.g., recent IV antibiotics, structural lung disease) should receive coverage for MDR gram-negative bacilli.
Methicillin-Susceptible Staphylococcus aureus (MSSA)
- Empiric therapy:
- Nafcillin or oxacillin are the preferred agents
- Dicloxacillin is preferred in the community setting
- Cefazolin is an alternative
- Clindamycin or vancomycin can also be used, but are not preferred
Directed Therapy for Important Gram-Negative Pathogens
- Haemophilus influenzae is the most common gram-negative cause of CAP.
- Targeted therapy based on culture and sensitivity testing.
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Description
This quiz covers the essential aspects of pneumonia, including its definition, causes, and classifications. Learn about pneumonia's impact on various age groups and the specifics of hospital-acquired pneumonia. Test your knowledge on this critical health issue affecting millions worldwide.
