Lower Respiratory Tract Infections - Community Acquired Pneumonia Flashcards
Definition of community-acquired pneumonia
Pneumonia that developed outside of the hospital or within the first 48 hours of hospital admission
Three common ways to acquire community acquired pneumonia
-Aspiration
-Aerosolization
-Bloodborne
What is the most common pathogenic organism for CAP?
Virus
What microorganisms are primarily transferred through aerosolization to cause CAP?
-Viruses
-Mycobacterium tuberculosis
-Endemic fungi
What is the most common pathway to cause CAP?
Aspiration
Common bacterial pathogens that cause CAP
-Streptococcus pneumoniae
-Haemophilus influenzae
-Mycoplasma pneumoniae
-Legionella pneumophila
-Chlamydia pneumoniae
-Staphylococcus aureus
Which patient populations have an increased prevalence in streptococcus pneumoniae?
-Asplenia
-DM
-Immunocompromised
-HIV
-Chronic cardiopulmonary/renal disease
Risk factors for strep pneumoniae drug resistance
-Age less than 6 or over 65
-Prior antibiotic therapy
-Co-morbid conditions
-Day care
-Recent hospitalization
-Close quarters
Prevalence of penicillin resistance in strep pneumoniae across the US
3%
Prevalence of macrolide resistance in strep pneumoniae across the US
45-50%
What gram-stain is mycoplasma pneumoniae?
Atypical bacteria so it will not be identified on gram stain
How is mycoplasma pneumoniae spread?
Person-to-person contact so increased risk in close contact populations
How do mycoplasma pneumoniae symptoms typically present?
2-3 week intubation period followed by a slow onset of symptoms
What are symptoms commonly present with mycoplasma pneumoniae infections?
-Persistent, non-productive cough
-Fever
-Headache
-Sore throat
-Rhinorrhea
-N/V
-Arthralgia
What does imaging look like in patients with mycoplasma pneumoniae?
More pronounced with patchy, interstitial infiltrates
What gram-stain is legionella pneumophila?
It is an atypical pathogen so it does not appear on a gram stain
Where is legionella pneumophila typically found?
Found in water and soil
How is legionella pneumophila spread?
Spread by aerosolization
Which patient populations are at an increased risk of legionella pneumophila?
-Older males
-Chronic bronchitis
-Smokers
-Immunocompromised
What is the prevalence of staph aureus in CAP?
1-2%
Risk factors for MRSA?
-2-14 days post-influenza
-Previous MRSA infection/isolation
-Previous hospitalization
-Previous use of IV antibiotics
What tests are important to get in staph aureus infections?
MRSA nasal PCR
Which pathogens are common in alcoholism?
-S. pneumoniae
-Anaerobes
-K. pneumoniae
Which pathogens are common in COPD/smoker?
-S. pneumoniae
-H. influenzae
-Moraxella cattarhalis
-Legionella spp.
Which pathogens are common in post influenza pneumonia?
-S. pneumoniae
-S. aureus
-H. influenzae
Which pathogens are common in structural lung disease (cystic fibrosis, bronchiectasis, etc.)?
-P. aeruginosa
-S. aureus
Which pathogens are common in recent antibiotic exposure?
-S. aureus
-P. aeruginosa
Clinical presentation of CAP
-Sudden onset of fever
-Chills
-Pleuritic chest pain
-Dyspnea
-Productive cough
-Gradual onset with lower severity for mycoplasma and chlamydia pneumoniae
Clinical presentation of CAP in elderly patients
-Classic symptoms may be absent (afebrile, mild leukocytosis)
-More likely to have decrease in functional status, weakness, and mental status changes
Important vitals for CAP
-Febrile
-Tachycardia
-Hypotensive
-Tachypnea
What does a chest x-ray look like in CAP?
-Dense lobar consolidation or infiltrates = suspicion for bacterial origin
-Patchy, diffuse, interstitial infiltrates = atypical or viral pathogens
What are common sputum characteristics to look for in CAP?
-Color
-Amount
-Consistency
-Odor observed
Which gram stains should you only evaluate in CAP?
- > 25 PMNs
- < 10 epithelial cells
What gram stain would be indicative of S. pneumoniae?
Gram positive diplococci
What gram stain would be indicative of H. influenzae?
Gram negative coccobacilli
Should you get a respiratory culture in CAP?
Controversial - negative in 40-50% of patients with CAP and difficult to obtain clean sample
Important to note about blood cultures
Always get 2 sets
Important markers to look at in CAP
-WBC with differential
-SCr, BUN, electrolytes, LFTs
-Pulse oximetry
-Urinary antigen test (S. pneumoniae, legionella pneumophila)
-Nasopharyngeal PCR swabs to test for MRSA or viral pathogens
When do you take cultures?
In severe CAP
What major criteria must be met in order to diagnose someone as severe CAP?
(Need 1)
-Septic shock requiring vasopressors
-Respiratory failure requiring mechanical ventilation
What minor criteria must be met in order to diagnose someone as severe CAP?
(Need at least 3)
-Respiratory rate 30 or more
-PaO2/FlO2 250 or less
-Multilobar infiltrates
-Confusion/disorientation
-Uremia (BUN 20 or more)
-Leukopenia (WBC less than 4000)
Thrombocytopenia (Plt < 100,000)
-Hypothermia (temp less than 36C)
-Hypotension requiring aggressive fluids
What are some tools used during treatment of CAP?
-Procalcitonin
-Pneumonia severity index (PSI)
-CURB-65
What is procalcitonin used for when treating CAP?
-Should not be used to determine need for antibiotics for CAP
-Useful in guiding duration of treatment if obtained throughout hospitalization
What is CURB-65?
-Confusion
-Uremia (BUN over 19)
-Respiratory rate 30 or more
-Hypotension (SBP under 90 and DBP 60 or less)
-Age 65 or more
What are the supportive treatments for patients with CAP?
-Humidified oxygen
-Bronchodilators
-Fluids
-Chest physiotherapy
CAP outpatient empiric therapy for patients WITHOUT comorbidities or risk factors for antibiotic resistance
-Amoxicillin 1 gm PO Q8H
-Doxycycline 100 mg PO BID
-If macrolide resistance is less than 25%, azithromycin 500 mg PO on day 1, followed by 250 mg PO on days 2-5
CAP outpatient empiric therapy for patients WITH comorbidities or risk factors for antibiotic resistance
-Monotherapy: Respiratory FQs (levo, moxi)
-Combo therapy: Beta-lactam (Augmentin, Cefpodoxime, cefuroxime) + macrolide or doxycycline
Non-severe CAP inpatient empiric therapy for patients WITHOUT MRSA/pseudomonas risk factors
-Monotherapy: Respiratory FQs (levo, moxi)
-Combo therapy: Beta-lactam (ampicillin/sulbactam, ceftriaxone) + macrolide
Severe CAP inpatient empiric therapy for patients WITHOUT MRSA/pseudomonas risk factors
-Combo therapy: Respiratory FQ + beta-lactam (ampicillin/sulbactam, ceftriaxone)
-Combo therapy: Beta-lactam (ampicillin/sulbactam, ceftriaxone) + macrolide
When would doxycycline be used inpatient for CAP?
IV/PO may be used if FQ or macrolide contraindicated
What are some risk factors for MRSA in CAP patients?
-2-14 days post-influenza
-Previous MRSA respiratory infection/isolation
-Previous hospitalization and use of IV antibiotics within last 90 days
What treatment would be used if a patient with CAP has a risk factor for MRSA?
-Vancomycin
-Linezolid
What are some risk factors for pseudomonas in CAP patients?
-Previous pseudomonas respiratory infection
-Previous hospitalization and use of IV antibiotics within last 90 days
What treatment would be used if a patient with CAP has a risk factor for pseudomonas?
-Piperacillin/tazobactam
-Cefepime
-Meropenem
What is the preferred therapy for a patient who has CAP and has penicillin susceptible strep pneumoniae?
-Penicillin G
-Amoxicillin
What is the alternative therapy for a patient who has CAP and has penicillin susceptible strep pneumoniae?
-Ceftriaxone
-Respiratory FQ
-Doxycycline
What is the preferred therapy for a patient who has CAP and has penicillin resistant strep pneumoniae?
-Ceftriaxone
-Respiratory FQ
What is the alternative therapy for a patient who has CAP and has penicillin resistant strep pneumoniae?
-Vanco
-Linezolid
What is the preferred therapy for a patient who has CAP and has haemophilus influenzae?
-Second and third generation cephalosporin
-Unasyn
-Augmentin
What is the alternative therapy for a patient who has CAP and has haemophilus influenzae?
-FQ
-Doxycycline
-Macrolide
What is the preferred therapy for a patient who has CAP and has mycoplasma pneumoniae and/or chlamydia pneumoniae?
-Macrolide
-Doxycycline
What is the alternative therapy for a patient who has CAP and has mycoplasma pneumoniae and/or chlamydia pneumoniae?
FQ
What is the preferred therapy for a patient who has CAP and has legionella pneumophila?
-FQ
-Azithromycin
What is the alternative therapy for a patient who has CAP and has legionella pneumophila?
Doxycycline
What is the preferred therapy for a patient who has CAP and has MSSA?
-Cefazolin
-Nafcillin
What is the alternative therapy for a patient who has CAP and has MSSA?
-Vanco
-Clindamycin
What is the preferred therapy for a patient who has CAP and has MRSA?
-Vanco
-Linezolid
What is the alternative therapy for a patient who has CAP and has MRSA?
-Ceftaroline
-Bactrim
What is the preferred therapy for a patient who has CAP and has anaerobes?
-Beta-lactam/beta-lactamase inhibitor
-Add metronidazole if using cephalosporin
What is the alternative therapy for a patient who has CAP and has anaerobes?
-Carbapenem
-Clindamycin
What is the preferred therapy for a patient who has CAP and has enterobacterales?
-Third/fourth gen cephalosporin
-Carbapenem
What is the alternative therapy for a patient who has CAP and has enterobacterales?
-Beta-lactam/beta-lactamase inhibitor
-FQ
When would corticosteroids be used for CAP?
Only recommended if the patient has CAP AND septic shock
How long should the duration of CAP therapy be?
-Ensure clinical stability prior to discontinuing antibiotics
-Continue antibiotics until clinical stability for a minimum of 5 total days
What should vitals be for someone to be clinically stable?
-Temperature 38C or lower
-HR 100 or less
-RR 24 or less
-SBP 90 or more
-O2 sat. 90% or more on room air
-Baseline mental status
