Flashcards in Community acquired pneumonia Deck (46):
What is the most common cause of CAP?
gram + -> strep pneumo
Pathogenesis of pneumonia?
inflammation of parenchymal structures of the lung in the lower respiratory tract (alveoli and bronchioles)
Differentiation b/t CAP and nosocomial pneumonia?
CAP: occurred outside of hospital or w/in 48 hours of hospital admission
- in a person who has not resided in a nursing home or hospital in past 2 weeks
Nosocomial pneumonia: hospital acquired, ventilator associated, health care associated (more drug resistant and virulent)
Typical and atypical pneumonia?
typical: caused by bacteria that multiply in alveoli, neutrophils and pus in alveoli, congregate in alveoli sacs, multiply and produce pus
atypical: caused by infectious agents that multiply in spaces b/t alveoli (septum and interstitum)
- viral infections, mycoplasm (lack a cell wall around their cell membrane)
Pathogenesis of pneumonia?
- defect in usual respiratory defense mechanisms (cough, cilia, immune response)
- large infectious inoculum or a virulent pathogen overwhelms the immune system
Definition of CAP?
pneumonia infection occurred outside the hospital or w/in 48 hrs of hosp. admission
- patients who are residents of long term care facilities are not included her because they are living in a healthcare facility
Epidemiology of CAP
- 4-5 million cases a year in U.S.
- 25% will require hospitalization
- most common infectious cause of death world wide
- among top 3 causes of death worldwide
- incidence peaks in winter months
- more common in older adults > 65
- incidence has decreased since pneumococcal vaccine
RFs for CAP?
- advanced age
- alcoholism (aspiration)
- tobacco use
- gastric acid suppressive therapy: allows pathogens to survive in gastric contents that normally would be killed by acid
- regular contact with kids (daycare)
- frequent visits to a health care provider
Most common causative agents of CAP?
- strep pneumo (#1 causative agent)
- H. influenzae
- mycoplasma pneumoniae
- chlamydia pneumoniae
- staph aureus
- Neisseria meningitidis
- M catarrhalis
- klebsiella pneumonia
- gram - rods
Viral causes of pneumonia?
influenza A & B
respiratory syncytial virus (kids)
Outpt causative agents of pneumonia?
- S. pneumoniae
- M. pneumoniae
- C. pneumoniae
- respiratory viruses
hosp. non-ICU causative agents of pneumonia?
- S. pneumo
- M. pneumo
- C. pneumo
- H. influenzae
- respiratory viruses
Inpatient ICU agent of pneumonia?
- S. pneumo
- Legionella (bad)
- H. influenza
- staph aureus*
What other etiologies might be causing pneumonia?
- fungal: if insidious onset with a possibility of immunocompromise (on immunosuppressive meds, HIV?) consider fungal etiologies
What factors would suggest legionella as the causative agent?
Recent travel within 2 weeks, hotel stays or cruise ships
- high fever >104 F
- multilobar involvement
- GI sxs (watery diarrhea) ****unique to legionella
- neuro involvement
- diffuse parenchymal involvement on xray
Tips to determine etiology?
- strep pneumo: most common, may have rust colored sputum
- mycoplasma pneumonia:
General sxs of pneumonia
- +/- sputum production
- pleuritic chest pains
- abdominal pain
Signs of pneumonia
- appear acutely ill
- may have hypothermia (elderly) 36 C
- decreased SpO2
- Rales/crackles (inspiratory)
- bronchial breath sounds
- dullness to percussion
Elderly presentation of pneumonia?
- more likely to have subtle symptoms
- decline in fxnl status
- confusion or change in mental status
- tachypnea is common
out pt dx tests?
urinary antigen testing: +/- (strep pneumo, legionella)
( maybe not necessary in younger pts)
inpt dx tests?
sputum gram stain
urinary antigen testing: s. pneumo, legionella
- rapid antigen test for influenza
- prior to initiation of abx therapy: sputum culture (2 sets) -> want to start abx within 6 hours
- CBC with diff
- CMP (legionella messes with electrolyte balance)
- arterial blood gases for hypoxic patients
- consider HIV testing in all adult patients
What kind of CXR should be ordered and what will you see on the films?
- always order a PA, and lateral Xray if possible
- findings: patchy opacities, lobar consolidation with air bronchograms, diffuse alveolar or interstitial opacities, pleural effusions, cavitation
Why are CXRs helpful?
- helpful to assess severity
- assess response to therapy
- may take 6 weeks to completely clear (f/u until CXR is clear)
What should be considered if pt presents with pleural effusion?
- consider a thoracentesis
- dx eval of pleural fluid includes: glucose, LDH, total protein, leukocyte count, pH, gram stain and culture
*fluid will shift if turned on side
- pleural effusion occurs in cancer, cancer increases risk for pneumonia because of decrease in immunity
When should fungal dx testing be done?
- order fungal tests on sputum and test for mycobacterium if cavitary opacities are seen
- likely need to obtain samples from bronchoscopy
When should CA-MRSA pneumonia be considered?
- influenza infection preceded present illness
- necrotizing pneumonia (destroying the lung tissue)
- empyema: collection of pus secondary to infection
- respiratory failure or shock
- if MRSA infection: tx with vanco or linezolid
* CA MRSA is genetically different from HA MRSA
1st step in tx of pneumonia?
- determine if the pt warrants hospital admission or if it safe to tx as an output
What is CURB-65?
U= BUN> 19 mg/dl
R= RR> 30 min
B= BP= 90/60
age = >65
* 1 pt for each yes, hospitalize if > 1, higher the points the higher the mortality
* get confusion from being hypoxic, hyper carbon -> dehydration, elect. imbalance
* hypotension: worried about sepsis
Is CURB-65 a good indicator of tx for pneumonia?
- low sensitivity (39%) for ID of those needing intensive respiratory support
- it is good at predicting 30 day mortality:
2 = 9.2%
3 or more = 15-40%
How sensitive is the pneumonia severity index?
- 74% sensitivity for prediction of those needing intensive respiratory support
Empric abx tx for non-hosp and no comorbidity patients?
- azithro or clarithomycin or doxy (covers H. flu and is better for pts with hx of smoking
Empiric abx tx for non-hosp. patients with comorbidities?
- Resp FQ or azithro or clarithro + high dose amox or high dose Amox-CL or cefdinir, cefpodoxime, cefprozil
Empiric abx tx for hospitalized pts not in the ICU?
- Respiratory FQ (levo)
- or macrolide + Beta lactam: cefriaxone, ampicillin, cefotaxime
Empiric abx tx for hospitalized pts in the ICU?
- respiratory FQ or Azithro
- + antipseudomonal B-lactam: cefotaxime, ceftriaxone, ampicillin/sublactam
- if at risk for pseudomonas add antipneumococcal + antipseudomonal b-lactams: piperacillin/tazobactam, cefepime, imipenem, miropenem + cipro or levo
antipseudomonal B-lactam + aminoglycoside + azithro or resp. FQ
* If MRSA is suspected: add vanco
When is the best time to start abx?
- best outcomes if abx started within 6 hours of admission
- customary to require first dose to be given in ED
Why would you change the therapy?
- based on severity of presentation
- recent abx use in the last 3 months
- post influenza infection -> think staph (MRSA)
- suspicion of drug resistant organisms in the community
- after obtaining culture and sensitivity results
Duration of abx therapy?
- min. of 5 days (tx longer then a week, no benefit)
- afebrile for 48-72 hours
- average for meds other than azithro 5-7 days unless severe infection or other sites infected
- azithro has a very long half life so duration of therapy doesn't equate to other drugs
Prevention of pneumonia?
- pneumococcal vaccine (against 23 strains of S. pneumonia), seasonal influenza vaccine
RFs of anaerobic pulmonary infections?
- decreased level of consciousness due to drug or ETOH use
- general anesthesia
- CNS disease
- impaired swallowing
- hiatal hernia
- tracheal tubes
- NG tubes
- periodontal disease
- poor dental hygiene
Pathogenesis of anaerobic pulmonary infections?
- inhalation of oropharyngeal secretions colonized by pathogenic bacteria: macro aspiration and chronic micro aspiration
- Goes to dependent lung zones: posterior segments of upper lobes and superior and basilar segments of lower lobes
What do anaerobic lung infections cause?
- necrotizing pneumonia
- lung abscess
What are the anaerobic pathogens?
- Prevotella melaninogenica
- Fusovacterium nucleatum
Symptoms of anaerobic lung infection?
fever, wt loss, malaise
- cough productive of foul smelling sputum
Work up of anaerobic lung infection?
- CXR and most likely CT scan of chest (won't see extent of damage with CXR -> need CT)
- can't do sputum culture due to contamination from oropharyngeal secretions
- if sputum sample is needed:
do a bronchoscopy or transthoracic/transtracheal aspiration
- if aspiration suspected a swallowing eval is needed -> RF: is having sleep apnea
Tx of anaerobic lung infection?
or amoxicillin or PCN G + metronidazole
- longer courses of therapy are generally needed, continue abx until CXR improves which may be a month or more
- lf lung abscess -> continue abx until resolution of abscess
- may require surgical removal of abscess or empyema