Pneumonia Flashcards
Pneumonia - Definitions
-infection of the lung parenchyma
-Significant cause of morbidity and mortality
-Often misdiagnosed and undertreated
-Etiology depends on particular type of pneumonia
Categories:
-Community-acquired pneumonia (CAP)
-Hospital-acquired pneumonia (HAP)
-Ventilator-associated pneumonia (VAP)
-Health care-associated pneumonia (HCAP)
-newest classification to include multi-drug resistant pathogens in outpatients
Pneumonia - pathophys
Microorganisms gain access to the lower respiratory tract in multiple ways
1. Aspiration from oropharynx* (MC)
-common during sleep in elderly and in pts w/decreased levels of consciousness
2. Inhalation of respiratory droplets
3. Hematogenous spread (i.e.-triscuspid endocarditis)
4. Contiguous spread (i.e.-infected pleural space)
Mechanical factors that help in host defense:
-Hairs/turbinates in nares capture inhaled particles
-Gag reflex and cough mechanism help to protect from aspiration
-Normal flora in oropharynx help to prevent pathogenic bacteria from attaching
-When above barriers are overcome or aerosolized particles are small enough to get by alveolar macrophages help to clear/kill off pathogens
-When the capacity of the alveolar macrophages is exceeded -> pneumonia occurs
-Alveolar macrophages initiate a host inflammatory response -> fever
-Neutrophils are attracted to the lung -> leukocytosis and increased purulent secretions
-Inflammatory mediators and neutrophils create an alveolar capillary leak (localized) -> infiltrate on x-ray and rales on auscultation
-Capillary leak, hypoxemia, secretions, bronchospasm, resp. drive -> dyspnea
Pneumonia: pattern
Lobar: involves entire lung lobe
- Bronchopneumonia: patchy infiltrate in 1 or several lobes
- Interstitial pneumonia: involves interstitial tissue in lungs, not alveoli
- Miliary pneumonia: numerous discrete lesions caused by hematogenous spread
CAP
pneumonia which develops in a pt who has not been recently hospitalized
Etiology:
-bacteria*, fungi, viruses, protozoa
-Streptococcus pneumonia (most common)
“Typical” organisms:
-S. pneumoniae, H. influenzae, S. aureus, Klebsiella pneumoniae, Pseudomonas
“Atypical” organisms:
- Mycoplasma pneumonia, Chlamydia pneumonia, Legionella, influenza viruses, adenoviruses, RSV
- cannot be cultured on standard media or viewed on Gram’s stain*
- resistant to B-lactams, must be treated w/macrolide, fluoroquinolone, or tetracycline
- Approx. ~80%-outpatient, ~20%-inpatient
- Results in 600,000 hospitalizations and 45,000 deaths/annually
- Huge financial impact-$9-10 billion/annually
- Incidence highest among young and elderly
RF’s: (CAP in general) -Alcoholism -Asthma -Immunosuppression -Institutionalization -Age >/= 70 yrs old RF’s: (Pneumococcal pneumonia-S. pneumo*) -Dementia -Seizure disorder -Heart failure -Cerebrovascular dis. -Alcoholism -Smoking -COPD -HIV
CAP - Sxs
(varies in severity and rate of progression)
- Fever/chills - Sweats - Cough (typically productive) - Myalgias - Fatigue - +/-Dyspnea - +/-Headache - +/-Pleuritic chest pain - +/- GI sxs (n/v/diarrhea)
Pneumococcal pneumonia:
-URI followed by bone-shaking chill, rapid fever, cough with rust-colored sputum
Mycoplasma pneumonia: “walking pneumonia”
-Indolent onset, non-productive cough, myalgias/arthralgias, skin rashes, +/- neurological sxs (resolve w/infxn)
Chlamydia pneumonia:
-Subacute onset w/pharyngitis, sinusitis, bronchitis, and pneumonia
CAP - PE findings
- Fever
- Tachypnea
- Tachycardia
- Normal or decreased pulse oximetry
- Use of accessory muscles for respiration
- Crackles, rales, wheezes on auscultation
- Dullness to percussion
- Increased or decreased tactile fremitus (consolidation or fluid)
- Elderly may have atypical signs-(i.e.-worsening confusion)
CAP - Dx
-Clinical dx: hx, physical, radiographic findings
-Etiologic dx: requires addition of labwork
Clinical dx:
-Details history is essential to help r/o DDx
-CXR: often necessary to differentiate from DDx
-CBC: often done but not necessary if confident of dx and planning to treat as outpatient
-Clinical information and CXR typically sufficient to treat as outpatient*
CXR:
-May be normal early on in course*
-Most often reveals infiltrate(s)
-May reveal a pleural effusion
-May help to reveal underlying disease (CHF, COPD, neoplasm)
Gram’s stain and sputum culture:
-Some pts may not be able to produce a sample
-If in ICU and intubated-sample can be obtained by deep suction aspirate or bronchoalveolar lavage
-Abx (if previously started) may interfere
-Greatest benefit is for unsuspected/resistant pathogens*
CBC:
-Typically reveals leukocytosis
Blood cultures: (2 sets)
-Yield may be low (even before Abx initiated)
-Routine for hospitalized pts in the past, currently recommended for high-risk pts and those who fail to respond to tx
Urine antigen tests:
-High specificity/sensitivity for Legionella pneumoniae
-Can also be used for pneumococcal pneumonia
PCR:
-Amplify a microorganism’s DNA or RNA are available but generally limited to research
-Could be helpful to identify pts suitable for ICU
Serology:
-Not helpful because of time required to obtain results
CAP- Tx
OUTPATIENT:
Healthy and no Abx in past 3 mos: (oral)
-Macrolide OR Doxycycline (typically 7-10 days-typical microorganisms, 10-14-atypical )
Comorbidities or Abx w/in past 3 mos: (oral)
-Respiratory FQ OR B-lactam + Macrolide
INPATIENT:
Non-ICU
-Respiratory FQ OR B-lactam + Macrolide (typically IV)
ICU
-B-lactam +Macrolide OR Respiratory FQ (IV)
Special considerations for suspected Pseudomonas and MRSA*
- Pts who are not responding to therapy need re-evaluation by day 3 (sooner if worsening)
- Fever and leukocytosis typically resolve w/in 2-4 days in healthy pts
- Chest x-ray abnormalities may require 4-12 weeks to fully resolve
- F/U chest x-rays are usually done 4-6 wks after discharge
Legionnaires’ Disease
- a type of pneumonia caused by breathing in mist from water that contains the bacteria
- Etiology: Legionella (gm- bacteria)
- Outbreaks occur from water towers, air conditioners, condensers, hot tubs, showerheads etc.
- RF’s: age > 65, tobacco use, lung dis., immunocompromised
- Sxs: gradual onset (2-10 day incubation)
- cough (dry), fever, rigors, HA, fatigue, weakness,respiratory distress, GI upset, confusion
- rapidly progressive pneumonia, multiorgan involvement
- Tx: Macrolides, Tetracyclines, FQ’s
- Can be life-threatening but most recover completely w/Abx
Viral Pneumonia
inflammation of the lungs due to infection by a virus Etiology: -Influenza -Parainfluenza -RSV -Adenovirus -Varicella -Coronavirus (SARS) RF’s: -young children and elderly -premature babies -organ transplant pts -pts receiving chemotherapy -HIV -children w/heart and lung problems Sxs: (typically milder than bacterial pneumonia) -cough -dyspnea -fever/chills -+/-HA -fatigue -+/-confusion in the elderly PE findings: -fever, cough, +/-decreased pulse ox, +/-tachypnea Dx: -based on hx, physical and imaging/labs if necessary -CXR done if pneumonia suspected -consider CBC and nasal swabs for particular viruses if tx plan will change (i.e.-influenza, RSV) Tx: Mainstay is symptomatic*-rest, fluids, simple analgesics
SARS
(Severe Acute Respiratory Syndrome): a serious form of pneumonia caused by coronavirus
Etiology: Coronavirus
-First reported in Asia-1993
-Spread by respiratory droplets
Sxs:
-Mild respiratory sxs initially
-After 2-10 days develop cough, dyspnea, F/C, fatigue, myalgias, HA
Dx:
-Hx (including travel to affected area), pneumonia on CXR, lab tests to confirm dx
Tx:
-Isolation if SARS suspected
-Abx if bacterial pneumonia also suspected
-Consider antivirals, steroids
-Consider O2, mechanical ventilation (if severe)
HCAP
Healthcare-associated pneumonia
- New classification system
- Represents transition b/w CAP and HAP (hospital-acquired pneumonia)
- Some studies have found a higher incidence of MDR (multiple drug resistant) pathogens than in HAP/VAP (hospital-acquired, ventilator-associated) pneumonias, other studies have not
- Management of HCAP due to MDR pathogens is similar to HAP/VAP
VAP
-Ventilator-associated pneumonia: pneumonia that develops in >/= 48 hours of mechanical ventilation (endotracheal tube or tracheostomy) Etiology: -Non-MDR: S. pneumo, H. flu, MSSA -MDR: Pseudomonas aeruginosa, MRSA, Klebsiella, Legionella -Less commonly: fungal (aspergillus) and viral pathogens Epidemiology: -Commonly assoc. w/pts requiring ventilation (peaks early and after 30 days) -Majority of cases in ICU, drops sig. once transferred to chronic-care facility or home -Colonization of oropharynx w/microorganisms -Aspiration of these organisms -Compromise of normal host defense RF’s: -Mechanical ventilation -Male gender -Age > 60 -Preexisting pulmonary disease (COPD etc.) -Coma -Surgery -Reintubation -Antibiotic exposure -Multiple organ system failure -Supine position, prolonged intubation Sxs: (similar to CAP) -Fever/chills -Cough w/sputum -Fatigue PE findings: (similar to CAP) -Fever -Tachypnea -Tachycardia -Decreased O2 saturation -Crackles, rales, wheezes on auscultation
VAP - Dx
-No single set of diagnostic criteria is reliable in diagnosis of VAP
-Conditions often mimic VAP in ICU setting
Qualitative-culture approach:
-Goal is to distinguish b/w tracheal colonization and true infection
-Specimen should be obtained before Abx initiated
-Several methods can be used-depends on availability and expertise (endotracheal aspirate, gram’s stain and culture, specimen brush method)
Clinical approach:
-Clinical Pulmonary Infection Score (CPIS)-allows for selection of lower-risk pts who may only need short-course or no Abx
-Point total based on:
-degree of fever
-degree of leukocytosis
-oxygenation
-chest x-ray findings
-tracheal aspirate growth
VAP/HCAP/HAP - Tx
- Depends on whether or not the pt has RF’s for MDR pathogens
- Majority of pts w/o RF’s for MDR should be treated w/a single Abx
- Majority of pts w/RF’s for MDR should be treated w/3 Abx (2 for Pseudomonas and 1 for MRSA)
- Once the etiology is determined pts w/MDR pathogens the regimen can be reduced to single or 2-drug combinations
- Tx failure is common in VAP (especially w/MDR pathogens)
- An elevated CPIS score on day 3 of therapy points to presumed tx failure
- Improvements (if occur) is usually evident w/in 48-72 hrs of initiation of Abx
- Multiple F/U chest x-rays often necessary
