Microaspiration of organisms into lungs is common and not usually pathogenic.
Why does pneumonia occur?
Pneumonia = microbes invade lungs, foster pathogenic inflammation.
Pneumonia risk increases when more pathogens are aspirated than the immune system can handle, and/or when the immune systems can't handle pathogens as well as usual.
(increased volume of pathogens, or decreased immune function)
what features of a patient make them more likely to have increased pathogen invasion into their lungs?
architectural changes: dysfunctional muscles for swallowing, altered mentation (chewing), altered ciliary clearance of debris from airways
what about a patient's immune system can increase their chances for pneumonia?
impaired immunity: if host neutrophils and lymphokines are impaired, microbes can multiply.
Immune response = neutrophils excrete inflammatory substances (interferon, ROS) and cause leakiness of vasculature.
Pneumonia: signs & symptoms?
-cough, fever, dyspnea, fatigue
Occasionally there are local symptoms:
--pleurisy from pus along the chest wall
--wheezing from accumulated snot in the airway
Pneumonia: Physical findings?
Crackles due to fluid in small airways
(Asymmetrical crackles in a patient with fever and cough are cardinal signs of pneumonia)
Egophony (E to A change)
Whispered pectoriloquy (enhanced sound due to consolidation)
increased vocal Fremitus (transmitted chest wall vibration w speech)
Asymmetrical dullness to percussion
Given that the s/s of pneumonia overlap with other syndromes, what is required to diagnose pneumonia?
Give a description of a patient presenting with pneumonia.
Patient will be febrile, with cough and dyspnea. Crackles on exam, and asymmetrical focal infiltrate on CXR.
Pneumonia: do you need to get labs?
If you do, what would they show?
Don't need to get labs
But there might be an abnormal WBC, neutrophilia, acidosis (severely ill).
May get sputum sample for Gram stain and culture. This would guide therapy.
In what patients is it most difficult to diagnose pneumonia? why?
Most difficult to diagnose in frail and immunocompromised patients - exactly the patients who are most susceptible.
Because their inadequate immune response to pneumonia stunts the s/s that you use to diagnose.
Have a low threshold for CXR, follow them closely.
What are the major causes of community-acquired pneumonia (CAP)?
- and other respiratory viruses
What are the major causes of healthcare-acquired pneumonia (HCAP)?
-Staph aureus (some MRSA)
-Gram negative rods
What are the major causes of ventilator-acquired pneumonia (VAP)?
Drug resistant non-Enterobacteriacea Gram neg rods (example: Pseudomonas)
Also, MRSA and Gram-neg rods, as with HCAP
A patient who gets sicker than most with pneumonia is likely to be infected with what pathogens?
Sicker patients with pneumonia are more likely to be infected with virulent pathogens like Staph Aureus and Gram neg rods.
What is a risk for aspiration pneumonia?
how does this cause pneumonia?
Excessive alcohol intake
impaired ability to protect the airway, vomiting.
Aspiration pneumonia: what are the likely pathogens?
Likely to be polymicrobial.
often caused by anerobes that reside in the oropharynx.
Pneumonia in an immunocompromised patient: what is the likely pathogen?
This will be a "protean beast"
Beyond the usual bacteria for CAP, HCAP, VAP, there may be atypical bacteria, yeast, fungi, even parasites.
Can viruses cause pneumonia? How can we diagnose?
Our diagnostic testing for this is bad; we fail to identify the presumptively viral cause most of the time.
Result: a lot of people with CAP from viruses get antibiotics. Which is ok with him since the benefits are greater than the downsides.
HOWEVER: there is one virus we can diagnose: influenza. Seasonal. Can be life-threatening. Treat with oseltamivir.
What is the general principle of pneumonia treatment?
Start by giving abx that cover whatever is epidemiologically likely.
Then if you get further information on the pathogen (culture), tailor your abx accordingly.
Avoid unnecessary exposure to broad spectrum abx, since this causes resistance.
Mild community-acquired pneumonia: what treatment should I start with?
Azithromycin or doxycycline
Want to cover S pneumoniae and "atypicals" like Mycoplasma
"Docs who use these drugs for viral bronchitis should be drawn and quartered"
Mild community-acquired pneumonia w hospitalized pt: what treatment should I start with?
Sometimes frail patients are hospitalized with mild CAP.
these patients on the floor (not ICU) can still be treated with azithromycin
Community-acquired pneumonia with sicker patient: what treatment should I start with?
Ceftriaxone (third generation cephalosporin)
Covers S pneumoniae, also gives expanded Gram neg rod coverage.
Still give azithromycin to cover Mycoplasma
May substitute a respiratory quinolone (like levofloxacin or moxifloxacin) but better to reserve these for pts who are allergic to Ceftriaxone/Azithromycin. Resistance is rising to these.
Community-acquired pneumonia, Severe: what treatment should I start with?
Add vancomycin to other treatment to cover MRSA and other staphlococci.
Discontinue vancomycin if MRSA is not eventually identified.
Hospital-acquired pneumonia: what treatment should I start with?
Atypical pathogens do not usually cause HAP therefore ceftriaxone and vancomycin should be sufficient
Hospitalized patients with pneumonia are more likely to be colonized with what pathogens (than CAP patients)?
What treatment does this call for?
More likely to be colonized with resistant Gram-neg rod pathogens.
May need expanded Gram-neg coverage such as ceftazidime.
What antibiotic class do we try not to over-use, so that we can prevent resistance? also we want to preserve this for patients who are allergic to PCN
Ventilator-acquired pneumonia: what treatment should I start with?
What pathogens are these patients likely to have?
What would be the first line therapy for the sickest and most antibiotic-exposed patients?
VAP pts likely to have MRSA and antibiotic-resistant Gram-neg rods
Start with Vancomycin/Zosyn or Vancomycin/Ceftazidime
Sickest pts: Carbapenems. First line for extremely sick patients. If patient is not extremely sick, reserve Carbapenems for times when they are absolutely required. (ie, bugs resistant to other meds are identified on culture)
Pneumonia in immunocompromised patients: what are the factors to consider when treating?
Individualize based on:
-the type of immunocompromise
-patient risk factors (travel, sick contacts)
-clinical phenotype such as x-ray appearance
What should I consider when seeing a patient with pneumonia, if I want to be a diagnostic rockstar?
-TB risk factors (exposure, health care work, homelessness/prisons, travel to endemic areas, HIV)
-Animal exposures (bats, birds, parturient beasts
-Activity risk factors in immunocomp patients (gardening, exposure to construction sites)
Pneumonia: what are the 3 main ways to prevent?
-vaccinating against pathogens that are complicated by bacterial pneumonia
-treating the underlying causes of pneumonia susceptability
which vaccine helps prevent pneumonia?
what do kids get? what do at-risk adults get?
why are there different forms of the vaccine?
Kids: 7-valent pneumococcal conjugate polysaccharide vaccine (Prevnar)
Adults: 23-valent polysaccharide vaccine (Pneumovax)
Different forms because T cell immunity is required to mount a strong response to vaccine. Children are less able to respond to the vaccine but are also at increased risk for pneumococcal pneumonia. Conjugate version of vaccine helps stimulate responses in them despite their underdeveloped T cell immunity.
what other resp infection is a major cause of pneumonia worldwide?
how do we screen for this?
TB is a major cause of pneumonia worldwide.
Highly contagious, highly morbid.
Prevent via infection control
Screen for latent TB via PPD skin testing or Quantiferon-GOLD blood testing.