Week 3: Clinical and microbiologic aspects of Pneumonia

Question 1

History and PE findings of pneumonia

Answer 1

HISTORY
-cough: productive or non
-fever, shaking chills
-pleuritic chest pain
-headache, myalgias
-hx of splenectomy? s.pneumoniae
-hx of travel? mycoses
PE
-fever
-abnormal breath sounds
-signs of lung consolidation or effusion

Question 2

Lab findings of pneumonia

Answer 2

• sputum gram stain useful only if good specimen and not contaminated by oral secretions
• sputum culture sensitivity poor
• blood cultures should be done

Question 3

Streptococcus pneumonia

Answer 3

• most common cause of community acquired pneumonia
• gram positive diplococci, catalase negative, alpha hemolytic, sensitive to optochin, lancet shaped
• resistance: beta lactam resistance due to altered PBP, macrolide resistance due to target modification or efflux pump
• vaccines: 1)polysaccharide for adults 2) conjugated for kids, old, immunocompromised

Question 4

Haemophilus influenzae

Answer 4

• cause fo CAP
• small gram negative coccobacillus, aerobic/anaerobic
• requires growth factors X (hematite) and V (nicotinamide adenine dinucleotide)
• common causes otitis media, sinusitis, pneumonia in elderly and with COPD

Question 5

Moraxella catarrhalis

Answer 5

• gram negative coccobacillus
• common carried in URT
• causes otitis media, sinusitis
• pneumonia in elderly and those with underlying disease

Question 6

Klebsilla pnuemoniae

Answer 6

• gram negative bacillus in family Enterobacteriaceae
• has capsule, lactose fermenter
• patients at risk: Alcoholics (not really true), COPD, hospital
• clinical: necrotizing pneumonia, currant jelly sputum and bulging fissure sign

Question 7

Staph aureus and pneumonia

Answer 7

• gram positive occus, facultatitve anaerobe, catalase positive, coagulase positive
• uncommon cause of CAP
• most common cause of hospital acquired pneumonia
• lung necrosis and abscess formation

Question 8

Mycoplasma pneumoniae

Answer 8

• classical cause of atypical or walking pneumonia
• nonproductive paroxysmal cough, systemic symptoms of headache, myalgia
• blister on tympanic membrane with erythema: bullus myringitis
• CXR: interstitial pattern
• 5-20 yo affected, insidious onset,
• dx: PCR is best

Question 9

Legionella species

Answer 9

-gram negative rod with cell wall, ubiquitous in water and soil.
-intracellular parasite. L pneumophila responsible for 90% of infections
-water is major source, no person to person transmission
SYNDROMES
-Pontiac fever: mild, self limited, non pneumonic
-Legionnaires’ Disease: non specific with hyponatremia
DX: rinary antigen is good
-Rx with macrolide or quinolone

Question 10

Q Fever

Answer 10

• Caused by coxiella brunette
• has spore form which is infectious by inhalation, has not arthropod vector
• infects domestic animals
• acute disease: pneumonia, febrile disease
• chronic disease: endocarditis, granulomatous hepatitis
• assoc. with farming
• Rx: tetracyclins, fluoroquinolones

Question 11

Chlamydia Psittaci

Answer 11

• from pet birds to humans
• bacteria shed in bird feces and nasal passages
• asymptomatic to severe pneumonia: fevers, chills, nonproductive cough, pulse temperature dissociation

Question 12

Diagnostic and Therapy of pneumonia

Answer 12

-CXR required for dx
-tests for etiology: blood cultures and expectorated sputum
RX
-ideally based on identified organism but practically Rx should be started immediately to prevent mortality
-previously health: macrolide preferred
-Comorbidities: respiratory fluoroquinolone