Pulmonary Infections -Patel Flashcards
What is Community Acquired Pneumonia? What organism commonly causes it?
an infection that begins outside of the hospital or is diagnosed within 48 h of hospital admission in a patient who has not resided in a long-term facility for 14 days or more before the onset of symptoms
Streptococcal pneumonia is the most common
What is hospital acquired pneumonia? What does HCAP (healthcare acquired associated pneumonia) include? Why do we care about these?
HAP=48 hours after admission to the hospital
HCAP=non-hospitalized patients with extensive healthcare contacts like:
- Nursing home resident
- Hemodialysis patients
- Hospitalization for >2 days in last 90 days
both HAP and HCAP may be more resistant organisms–> need more broad based medication
What is the most common organism to cause lobar pneumonia?
Streptococcal pneumonia (gram + diplococci)
then Klebsiella (esp in alcoholics and diabetics)
What are the stages of lobar pneumonia?
- congestion 24 hours –> lots of exudate in alveoli–> hypoxia
- red hepatization (1-3 days)–> RBCs and PMNs inside ==> exudates, neutrophils and hemorrhage
- gray hepatization (4-8 days) –> degradation of RBCs =fibrinosppurative exudate
- resolution
What is bronchopneumonia? What bugs normally cause this?
Inflammation and exudate starts in bronchioles and extend to alveoli
Patchy distribution involving multiple** lobes
- Staph. aureus-secondary pneumonia after viral infection
- H influenza- pneumonia with COPD
- Pseudomonas- pneumonia is cystic fibrosis pts
- Legionella- source is water like water fountain or water from air conditioner–> pneumonia is immmunocompromised pts
What is the typical cause of interstitial pneumonia? What are the normal symptoms?
viral
mild symptoms –> does not affect the alveoli directly (just parenchyma)–> no hypoxia
no solid consolidation on x-ray
Which bug will present with GI symptoms and pneumonia?
Legionella
What is required on imaging for a diagnosis of pneumonia? If a pt with suspected pneumonia has a negative chest x-ray, what should you do next?
presence of infiltrate on imaging (chest x-ray) along with clinical finding
negative chest x-ray:
- repeat in 48 hours with empiric antibiotics
- CT chest
- consider other diagnosis
What labs should be ordered for a hospitalized pt with CAP or HAP?
- blood culture
- sputum culture
- urine antigen for lenionella and pneumococcus
optional for outpatient CAP
What determines whether a sputum culture is adequate?
-culture yield 25 neutrophils and <10 squamous epithelial cells on low-power field
What bug should you think of in a child with pneumonia and a middle ear infection?
mycoplasma
What is the specific diagnostic test for mycoplasma? Legionella? Streptococcal pneumonia?
Mycoplasma: serology for IgM and IgG, PCR
Legionella and strept pneumoniae=urine antigen test
What bug should be suspected in CAP found in a healthy pt?
strept pneumonia
What bug should be suspected in children < 5yo or adults >65 yo and/or functional asplenia?
H. influenzae
What bug should be suspected in pneumonia after influenza, lung abscess or nosocomial pneumonia?
Staph aureus
What is the outpatient treatment for pneumonia in a previously healthy pt with no risk of drug resistance? What if they have comorbidities or factors
- healthy: macrolide or doxycycline
- comorbidities: Beta-lactam + macrolide or doxycycline
OR flouroquinolones
What is the treatment for pneumonia in a hospital setting (CURB-65=2+)?
Beta lactam + macrolide
or resp FQ (reserve for beta-lactam allergic pts)
What is the treatment for severe pneumonia (CURB-65 >3)?
Potent antipneumococcal beta-lactam (cefotaxime, ceftriazone or ampicillin-sulbactam) + azithromycin or RFQ
When should MRSA pneumonia be suspected?
- Severe, rapidly progressive pneumonia
- During influenza season (superimposed bacterial pneumonia)
- Pneumonia with cavity on CXR (from PVL toxin)
- -> Tend to cause necrotization of lung tissue fast.
- Previous history of MRSA infection.
What 3 things should be checked in pts who do not respond to treatment?
wrong organism?
complication? (empyema, lung abscess, occult infection)
wrong diagnosis?
What can aspiration pneumonia lead to? What is a common pathophysiology of this?
chemical pneumonitis (abrupt onset of dyspnea with low grade fever, cyanosis and diffuse crackles)
lung abscess (necrotizing pneumonia)
*often due to compromised consciousness (alcoholism, anesthesia)
What are some signs of an aspiration pneumonia–> lung abscess (necrotizing pneumonia)? What are some causes of this?
- Patient is sick for few days
- Foul smelling sputum
- Chest x-ray shows consolidation with cavity
TANKS
- TB
- Anaerobes (Bacteroides, fusobacterium, peptostreptococcus, provetella)
- Nocardia
- Klebsiella (red currant sputum)
- S. aureus (PVL toxin)
If a pt is infected with mouth anaerobes, will the sputum culture be +?
probably not because the bugs need a special culture to grow
mixed flora is common in aspiration pneumonia
Where are lung abscesses likely to form? How long does this take?
Right lower lobe
takes 7-10 days for necrosis
