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Risk Factors

COPD HF DM

CRF/CRI CA CAD

Splenectomy liver disease neurologic disease

Medical Microbiology

² 40-60% unknown

² Viral

² Streptococcus pneumoniae (pneumococci)

§ Most common

§ Gram positive, lancet shaped diplococci or short chains

§ PCN resistance today is 30%+

§ Resistance is by alteration of penicillin binding proteins to penicillin, resistance to other classes of antibiotics also exists

§ Encapsulated organism

§ Red or brown rusty sputum

§ Acute onset with fever, chills, rigors

§ Vaccine available

² Haemophilus influenzae

§ Small gram negative rod, cocobacillus

§ 40%+ beta-lactamase producers

§ Encapsulated organism

§ Vaccine available

² Moraxella catarrhalis

§ Gram negative cocobacilli

§ Usually an infrequent isolate

§ 90%+ beta-lactamase producers

² “Atypical Pathogens”

§ Mycoplasma pneumoniae

· Smallest free living organisms

· No cell wall thus wall active agents are ineffective

· Have a 3 layered cell membrane

· Grow slowly

· Close contacts pneumonia

· Diagnosis with cold-agglutinin titer or antibody titer

§ Chlamydia pneumoniae

· Intracellular bacteria, mucous membranes of the lungs

· Have a unique growth cycle from a spore-like structure and they leave behind inclusion bodies that can be seen with special stain

· Diagnosed with immunofluorescence, DNA probes

§ Legionella pneumophila and spp.

· From the American Legion in 1976

· Gram negative rod, hard to stain

· Associated with water sources

· Common in smokers and alcoholics

· Seems to cause frequent hyponatremia

· Requires special media to culture

· Diagnosis is made with culture and urine antigen test

Clinical Investigation

² Conditions related to specific pathogens

Alcoholism Streptococcus pneumoniae

Anaerobes

Haemophilus influenzae

Legionella

Tuberculosis

COPD/Smoker Moraxella catarrhalis

Streptococcus pneumoniae

Haemophilus influenzae

Legionella

Bird exposure Chlamydia psittaci

Flu in the community Streptococcus pneumoniae

Haemophilus influenzae

Staphylococcus aureus