Infectious Diseases: Sepsis & Shock

Question 1

Systemic inflammatory response syndrome (SIRS)

Answer 1

• Dysregulated host inflammatory response.
• Presence of two or more of the following:
  
  • Temperature >38oC (100.4oF) or <36oC (96.8oF)
  • Heart rate >90 beats/min
  • Respiratory rate >20 breaths/min
  • WBC >12,000 cells/mm3, <4000 cells/mm3, or >10 percent immature (band) forms
• Can be result of noninfectious processes
• Sepsis = SIRS + Infection

Question 2

Severe sepsis

Answer 2

• Hypotension
  
  • Systolic blood pressure <90 mmHg
  • drop of >40 mm Hg from baseline
  • Reversible with intravenous fluid resuscitation

Question 3

Septic shock

Answer 3

• Sepsis not responding to IVF resuscitation
• Requires vasopressors

Question 4

Some causes of sepsis

Answer 4

• Meningitis: N. meningitides, S. pneumoniae, L. monocytogenes
• Pneumonia:
  
  • Community-acquired (top 3): S. pneumoniae, M. pneumoniae, H. influenzae
  • Nosocomial pneumonia (top 3): MRSA, Pseudomonas, E. coli
• Pyelonephritis: E. coli, Proteus, Klebsiella
• Peritonitis: aerobic and anaerobic gram -ve
• Cholangitis: E. coli, Klebsiella, Enterobacter
• Cellulitis: S. aureus (MSSA, MRSA), beta-hemolytic strep

Question 5

Sepsis & Shock Pathogenesis

Answer 5

• “Malignant intravascular inflammation”
• Balance of pro- and anti- inflammatory processes
• Small amounts lead to
  
  • Fever
  • Leukocytosis
  • Activation of complement
• Excessive production/release lead to
  
  • Dysregulated
  • Capillary leakage, hypovolemia → hypotension and poor tissue perfusion
  • DIC
  • Shock

Question 6

Effect of shock & sepsis on pulmonary

Answer 6

• Vascular permeability due to heart failure
• Noncardiogenic pulmonary edema

Question 7

Effect of shock & sepsis on renal

Answer 7

Decrease effective intravascular volume due to systemic hypotension -> Acute tubular necrosis

Question 8

Effect of shock & sepsis on CNS

Answer 8

• Hypotension can lead to brain hypoperfusion.
• Result of hepatic or renal dysfunction, metabolic encephalopathy
• Delirium? vs. CNS infection?

Question 9

Endocarditis Etiopath

Answer 9

Risk factors:

• Stenosis, sclerosis, prolapse
• Prosthetic valve
• Rheumatic
• IVDU
• Congenital: Tetraology
• VSD, bicuspid AV

Etiology

Secondary to primary focus of infection

• Usually transient
• Skin- Abscess
• GU- Pyelonephritis
• Pulmonary- Pneumonia

2. Endovascular source

• Usually sustained
• Infected intravascular device- (Catheter)

Pathogenesis

• Trauma to endothelium as result of turbulent flow
• Stimulates fibrin, platelet deposition
• Episode of transient bacteremia
• Likely suspects – staph, strep viridans (alpha hemolytic), enterococcus, coagulase -ve staph, HACEK (liver around mouth and cause subacute)
• Beta hemolytic organisms are uncommon causes of endocarditis: S.pyogenes Group A, S.agalactiae, GBS
• However, IV drug users, any microbe can cause endocarditis (bacteria & fungi)
• Virulence factors: biofilm

Sx: fever, new murmur, vascular embolic event, splenomegaly, splinter hemorrhages, Osler’s nodes (immune complex deposition) , Janeway’s lesions (septic emboli, microabscesses), Roth spots, hypopion, mitral valve vegatation,

• pulm: septic pulmonary emboli
• Spleen & liver: infarcts & abscesses
• MSK: septic arthritis, vertebral osteomyelitis
• CNS: Embolic stroke, infarct, hemorrhage