Community Acquired Pneumonia
Pneumonia is defined as infection of Lung Parenchyma.
CLASSIFICATION OF PNEUMONIA
Community Acquired Pneumonia (CAP)
Hospital Acquired Pneumonia - During or after hospital stay or associated with ventilator. These types of pneumonia tend to have organisms that are much more resistant.
Healthcare Associated Pneumonia are patient in nursing home, long term facility as well as patient in acute care hospital for more than 2 days in the past 90 days, IV therapy, woundcare and IV chemo wihtin the last 30 dyas and hemodialysis within the last 30 days.
PATHOGENESIS OF COMMUNITY ACQUIRED PNEUMONIA
Most common cause is microaspiration which overhwelm host defense, hematogenous, direct spread, and macroaspiration (Decrease gag, cough reflex) may all lead to pneumonia.
MICROBIOLOGY OF PNEUMONIA
TYPICAL Pneumonia tends to be more severe type of pneumonia. There tends to be more consolidation and mucupurulent sputum. Classic bacteria that causes pneumonia is Streptococcus pneumonia, Staphylococcus aureus, Klebsiella Pneumonia, Psueodmonas Aeroginosa, Hemophilus Influenza and Moraxella Catarrhalis.
ATYPICAL Pneumonia is less severe and also referred to as walking pneumonia and invades the epithelial cells and does not affect the alveoli wall. There is patchy diffuse and decrease sputum. Extrapulmonary symptoms is also common such as myalgia bradycardia splenomegaly, rash and CNS Symptoms. Non zoonotic causes include Mycoplasma, chalmydia pneumonia and Legionella which are all intracelular. Zoonotic is psitococas, Q Fever, and Tularemia. MOre commonly viruses such as influenza, parainfluenza and RSV and adenovirus.
RISK FACTORS FOR PNEUMONIA
Alcoholism - S. Pneumonia, oral anerobes, Klebsiella pneumonia and TB
COPD/Smoking - S. Pneumonia, H. Influenza, P. Aeroginosa, Moraxella, Legionalla
Lung Abscess - CA-MRSA, Oral Anaerobes, TB Fungal
Structural Disease - Psuedomonas, S. Aureus, Burklholderia
Influenza - S. Pnuemonia, S.A ureus
IV Drug Abusers - Psuedomonas, Anaerobes, S. PNeumonia TB
Farm Animals - Coxxiel Burnetti
Birds - Chlamydia
Rabbits - Tularemia
Bat-Bird - Histoplasma Capsilatuma
HIV Early - S. pneumonia, H. Influeanza, TB
Southwestern US - coccidioides Hanta virus
Hotel/Cruise Ships - Legionella
Bioterrorism - B. Anthracis, Yersinia Pestis, Tularemia
Aspiration - Gram neg, Oral anaerobes
Predisposing - hypoxemia, acidosis, toxic inhalation, pumonary embolism, uremia, malnutrition, lung cancer, asthma, AIDS, smoking Age greater than 70
Fungal - Aspergillus, Cryptococcus, Histoplasma, Coccidiomycosis
EVALUATION
Symptoms - mucupurulent cough or scanty watery cough, Fever, pleuritic chest pain, Nausea and vomiting, Mental status changes, myalgias rash splenomegaly.
Signs - tachycardia, RR more than 24 Auscultation audible crackles. Consolidation - dullness to percussion, Bronchial breathing increase vocal fremitus, Egophany
Labs - leukocytosis leftward shift, Anemia
X-Ray shows consolidation in lobar pneumonia and interstitial pneumonia shows a much more diffuse reticular picture.
CT-Scan - no evidence that CT Scan improves outcome
DETERMINE PATHOGEN OF PNEUMONIA
Outpatient not necessary unless critical agent such as legionella, influenza, MERS-COV, CA-MRSA, Bioterrorism.
Severe Pneumonia or ICU patient perform sputum, blood culture, urine antigen test, PCR, Serology, ELISA, Immunofluorescence. Biomarkers procalcitonin helps determine for use of anti-biotics. CRP greater than 40mg/L suggest bacterial. Blood cultures are difficult to get true positive result.
S. Pneumonia and H. Influenza have a higher false neg becuase grow easier, while S. aurues and GNB has a high false positive. Shoudl have greater than 25 neutrophils and less that 10 squamous epithelium.
MANAGEMENT OF PNEUMONIA
PNEUMONIA SEVERITY INDEX - rarely used
CURB-65- Confusion, Uremia, Respiratory Rate, BP less than 90 and age over 65. ICU if septic shock, mechanical ventilation requirements.
ANTI-BIOTICS
Outpatient - Macrolide or doxycycline
Comorbidities - add flouroquinolone or Betalactam with macrolide
After pathogen identification than base on sensitivity.
Admission - Flouroquinolon with B lactam and macrolide
ICU Admissions - Anti-pneumooccal B-lactam with Azithromycin and Flouroquinolone
Psuedmonas - Pipericillin tazobactam, cefipem, imepinem, meropenem and Aminoglycosdie, azithromycin or AMinoglycoside Floroquinolone.
CA-MRSA - Add vancomycin or Lenezolid
ADJUVANT THERAPY - Glucocorticoid, Decrease inflammatory response to pneumonia