Definition: infection of lung parenchyma
Empirically classified based upon location/risk factors
HCAP no longer entity in ISDA/American Thoracic Society guidelines
ISDA recommends only covering empirically for MRSA or pseudomonas in adults with CAP if "locally validated" risk factors for either pathogen and then, continuing empiric coverage while obtaining culture data to justify extended coverage
Commonly accepted risk factors for resistant pathogens (e.g. MRSA, pseudomonas) historically include:
Hospitalized for 2 or more days within past 90 days
Nursing home/long-term care residents
Receiving home IV antibiotics
Dialysis
Receiving chronic wound care
Receiving chemotherapy
Immunocompromised
Hospitalized for 2 or more days within past 90 days
Nursing home/long-term care residents
Receiving home IV antibiotics
Dialysis
Receiving chronic wound care
Receiving chemotherapy
Immunocompromised
Alcoholism
Immunosuppression (including steroids)
Structural lung disease
Malnutrition
Recent antibiotics
Recent hospital stay
Gram-positive
Streptococcus<unk> 
Staphylococcus aureus
Gram-negative
Haemophilus influenzae
Klebsiella<unk> 
Escherichia coli
Pseudomonas aeruginosa 
Moraxella catarrhalis
Atypical<unk> Chlamydophila<unk>  
Chlamydophila psittaci
Mycoplasma<unk> 
Coxiella burnetti 
Legionella pneumophila
Streptococcus<unk> 
Staphylococcus aureus
Haemophilus influenzae
Klebsiella<unk> 
Escherichia coli
Pseudomonas aeruginosa 
Moraxella catarrhalis
Chlamydophila<unk>  
Chlamydophila psittaci
Mycoplasma<unk> 
Coxiella burnetti 
Legionella pneumophila
Common
Influenza
Respiratory syncytial virus
Parainfluenza
Rarer
Adenovirus
Metapneumovirus
Severe acute respiratory syndrome (SARS)
Middle east respiratory syndrome coronavirus (MERS)
2019-nCoV (COVID-19)
Cause other diseases, but sometimes cause<unk> Herpes simplex virus
Varicella-zoster (VZV)
Measles
Rubella
Cytomegalovirus
Smallpox
Dengue
Influenza
Respiratory syncytial virus
Parainfluenza
Adenovirus
Metapneumovirus
Severe acute respiratory syndrome (SARS)
Middle east respiratory syndrome coronavirus (MERS)
2019-nCoV (COVID-19)
Herpes simplex virus
Varicella-zoster (VZV)
Measles
Rubella
Cytomegalovirus
Smallpox
Dengue
Histoplasmosis
Coccidioidomycosis
Blastomycosis
Pneumocystis jirovecii<unk> (PCP)
Sporotrichosis
Cryptococcosis
Aspergillosis
Candidiasis
Ascariasis
Schistosomiasis
Toxoplasma gondii
Streptococcus<unk> 
Anaerobes (e.g. Klebsiella<unk> 
Mycobacterium tuberculosis
S.<unk>  
Haemophilus influenzae
Moraxella 
Legionella
S.<unk>  
Gram-negative bacilli
H. influenzae 
Staphylococcus aureus 
Anaerobes
Chlamydophila<unk> 
S.<unk>  
H. influenzae 
M. tuberculosis
Pneumocystis jiroveci
Cryptococcus 
Histoplasma
Pseudomonas aeruginosa 
Burkholderia cepacia 
S. aureus
S. aureus 
Anaerobes 
M. tuberculosis 
S. Pneumo
Influenza
S.<unk>  
S. aureus 
H. influenzae
Pseudomonas aeruginosa 
Acinetobacter sp.
Stenotrophomonas maltophilia
Pneumonia 
Pulmonary
Pleuritis
Airway obstruction
Atypical pneumonia
Anaphylaxis
Lung abscess
Angioedema