Gram(-) Pulmonary Infectious Bacteria

Question 1

Klebsiella (pneumoniae) + Enterobacter

Answer 1

• short, encapsulated, facultative anaerobic, gram(-) rods
• necrotizing lobar pneumonia with cavitations
• 10% of nosocomial infections: P2P spread
• patients with COPD, endotracheal tubes, catheters, and immunosuppressed.
• complication from influenza or other viral infections
• characteristic THICK MUCOID SPUTIM
• can lead to fulminating, deadly septicemia–requires aggressive antibiotic treatment

Question 2

Legionella pneumophilia

Answer 2

• small, aerobic bacillus, gram(-)
• respiratory spread: aerosols of infected sources, NOT CONTAGIOUS
• pneumoina: Legionaire’s Disease (life-threatening) and Pontiac fever (milder, self-limiting)
• proliferate inside resident macrophages (granulomatous)–macrophages show eccentric nuclei pushed aside by vacuoles containing L. pneumophila
• alveolar necrosis, fever, nonproductive cough followed by hypoxia leading to death.
• Silver grain stain, Urine antigen test for diagnosis

Question 3

Pseudomonas aeruginosa

Answer 3

• Gram-negative, aerobic, coccobacillus bacterium
• highly antibiotic-resistant
• nosocomial bronchopneumonia, wound infections, UTI, and sepsis
• proteoglycan coat protects against ciliary action, complement, and phagocytes
• elastase, alkaline protease, cytotoxin (exotoxin A)– ADP-ribosylate/inhibit EF-2 (like diptheria toxin) facilitate tissue invasion
• ECTHYMA GANGRENOSUM: disseminated septicemia infections causes these skin lesions
• AGRESSIVE: rapid sepsis progression (exotoxin + endotoxin production)–hemorrhagic necrosis + thrombosis

Question 4

Meliodosis (Burkholderia pseudomallei)

Answer 4

• a pulmonary infection that can cause cavitary pneumonia with high fever
• splenomegaly, hepatomegaly, septicemia, septic arthritis and shock–SEVERE
• flourishes in wet environments (Vietnam) and enters skin through lesions, burns, or wounds as well as aerosolized droplets
• incubation time months to years
• liver, spleen abscesses in 25% of infected