Infections in the ICU
The Lancet, Volume 375, Issue 9713, Pages 463 – 474, 6 February 2010
Use of procalcitonin to reduce patients’ exposure to antibiotics in intensive care units (PRORATA trial): a multicentre randomised controlled trial
Treat cultures if in blood, in tissue, or 2 other sites simultaneously with signs of infection
CRP
acute phase proteins
Acute Phase ProteinsPositive Acute Phase Proteins: Proteins exhibiting increased plasma concentrations during the acute-phase response.
Factor VIII C reactive protein Ferritin Serum amyloid A Phospholipase A2 Haptoglobin a1 Alpha-1-protease inhibitor Ceruloplasmin C-1 esterase inhibitor Complement (C3 and C4) Mannose binding protein LPS binding protein
Prothrombin Plasminogen Immunoglobulins Plasminogen activator inhibitor-1 Alpha-1-acid glycoprotein Fibronectin Hemopexin Fibrinogen Pancreatic secretory trypsin inhibitor Inter-alpha protease inhibitor Alpha 2 macroglobulin C4b binding protein
Negative Acute Phase Proteins: Proteins exhibiting decreased plasma concentrations during the acute-phase response.
Albumin Transferrin Transthyretin (Pre-albumin) Alpha-2-HS glycoprotein
From Kushner I, Rzewnicki DL. The acute phase response. In: Mackowiak PA, ed. Fever, basic mechanisms and management, 2nd ed. Philadelphia: Lippincott-Raven; 1997:16576.
Table 6: Comparison of ESR and CRP (Ng. Br J Hosp Med 1998:58;521-523) [76]
ESR
CRP
Results affected by
Gender
Yes
No
Age
Yes
No
Pregnancy
Yes
No
Temperature
Yes
No
Drugs (e.g. steroids, salicylates)
Yes
No
Level of plasma proteins
Yes
No
Red blood cell factors
Hematocrit
Yes
No Morphology Yes No
Aggregability
Yes
No
Response to disease process
Intermediate
Early
Clinical assessment
Normal range of results
Wide
Narrow
Specificity
Moderate
High
Sensitivity
Moderate
High
Reproducibility
Low/moderate
High
Results available in
>60 min
<20 min
Relative cost
x1
x2-3
CRP and Orthopedic Problems
Septic Arthritis: Mean CRP is significantly greater in septic arthritis (90 mg/L) than in transient synovitis of the hip (10 mg/L). A mean CRP >20 mg/L and a temperature greater than 38.5°C (101.3°F) are independent predictors for septic arthritis with a sensitivity of 100% and a specificity of 87% [93]. Believe it or not, this is much better than hip arthrocentesis; only 36% to 79% of hip taps yield a positive culture [94-96]. Osteomyelitis: Radiographs are not usually helpful in diagnosing osteomyelitis; bony changes such as lucency and cortical disruption are usually not visible until 7 to 10 days after the onset of the infection. Bone scan is the gold standard for diagnosis (sensitivity 84% to 100%, specificity 70% to 96%) and is positive as early as 24 to 48 hours after the onset of symptoms [97,98]. The WBC will be elevated in a majority of cases, but normal values are seen frequently [99]. One study showed CRP elevated in 98% of patients with osteomyelitis, with a mean level of 71 mg/L [100]. Postoperative infection: Unlike ESR levels, which can remain elevated months after surgery (up to one year after hip arthroplasty revision), CRP levels have a defined range of rise and fall after orthopedic surgery (see Table 7). There is a rapid rise until day 2 or 3, then a rapid fall from days 3 to 5, followed by a more gradual fall until 14 to 21 days after surgery. While traditional indicators of inflammation and infection such as fever, white blood cell count, and ESR are affected by the surgical procedure itself, CRP tends to rise only with infection after this initial rise.
Table 7: Expected Post-Operative CRP Levels for Selected Orthopedic Procedures(Larsson et al. Clin Orthop 1992:275:237-242 [101])
Orthopedic Procedure Peak CRP level Accepted Highest Level
Primary hip arthroplasty (n = 109)
Day 3
116 mg/L
Revision hip arthroplasty (n = 9)
Day 3 136 mg/L Unicondylar knee arthroplasty (n = 39) Day 2 140 mg/L Lumbar microdiscectomy (n = 36)
Day 2
48 mg/L
Several studies in the orthopedic literature have demonstrated that the sensitivity, specificity, and diagnostic accuracy of serum CRP levels are much better than fever, white blood cell count, erythrocyte sedimentation rate and even physical examination. The articles which I read stressed that a single reading is helpful, but the real value lies in following the level over a period of days. Some authors have even suggested abandoning ESR in favor of CRP [102].
Strep Pneumoniae
Risk Factors
Age>65
Beta Lactam within past 3 months
ETOH
Immunosuppression
Multiple medical comorbidities
Childcare or Daycare Exposure
MIC>2 mcg/cc is high level resisitance
also confers resistance to erythromyin, cipro,cepalosporins, tetracycline
VRE
treat c amp/genta as first line
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colonic bacteria
e. coli finds optimal conditions in the peritoneal cavity bacteroides also can survive
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Sinusitis
always consider in all FUOs; very common in ventilated patients. (Critical Care 2005;9:R583)
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