Community acquired pneumonia Flashcards Preview

Infectious Disease > Community acquired pneumonia > Flashcards

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
- 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
respiratory syncytial virus (kids)
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?

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?

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
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
- 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:
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.