Community acquired pneumonia Flashcards
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
- COPD
- asthma
- immunosuppression
- underweight
- 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
- legionella
Viral causes of pneumonia?
influenza A & B rhinovirus respiratory syncytial virus (kids) adenovirus parainfluenza virus
Outpt causative agents of pneumonia?
- S. pneumoniae
- M. pneumoniae
- C. pneumoniae
- respiratory viruses
(less severe)
hosp. non-ICU causative agents of pneumonia?
- S. pneumo
- M. pneumo
- C. pneumo
- H. influenzae
- legionella
- respiratory viruses
(worse symptoms)
Inpatient ICU agent of pneumonia?
- S. pneumo
- Legionella (bad)
- H. influenza
- enterobacteriaceae*
- staph aureus*
- pseudomonas*
(*= virulent)
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
- male
- 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
- fever
- cough
- +/- sputum production
- dyspnea
- sweats
- chills
- H/A
- rigors
- pleuritic chest pains
- pleurisy
- hemoptysis
- fatigue
- myalgias
- anorexia
- abdominal pain
Signs of pneumonia
- appear acutely ill
- fever
- may have hypothermia (elderly) 36 C
- tachypnea
- tachycardia
- decreased SpO2
- Rales/crackles (inspiratory)
- bronchial breath sounds
- dullness to percussion
Elderly presentation of pneumonia?
- more likely to have subtle symptoms
- weakness
- decline in fxnl status
- confusion or change in mental status
- tachypnea is common
out pt dx tests?
CXR: +/- urinary antigen testing: +/- (strep pneumo, legionella) CBC: +/- BMP: +/- ( maybe not necessary in younger pts)
inpt dx tests?
CXR
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?
when:
- 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?
C= confusion 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:
0-1: 0.7-2.1%
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
or
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
- seizures
- general anesthesia
- CNS disease
- impaired swallowing
- GERD
- 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
- empyema
What are the anaerobic pathogens?
- Prevotella melaninogenica
- Peptostreptococcus
- Fusovacterium nucleatum
- Bacteroides
Symptoms of anaerobic lung infection?
onset: insidious
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?
- DOC:
Clindamycin
or augmentin
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
When should you consider an anaerobic infection?
if lung abscess, empyema, necrotizing pneumonia or sig. risk factors like recent LOC due to multiple factors
- not all cases of aspiration pneumonia are caused by anaerobes.
