Life-Threatening Infections: Diagnosis and Antimicrobial Therapy Selection

1 Copyright 2008 Society of Critical Care Medicine Objectives Understand and apply terminology specific to life-threatening infections List risk factors for development of infection Identify clinical manifestations of life- threatening infections and understand use of laboratory tests in diagnosis Describe variables used to guide selection of antimicrobial therapy Outline antimicrobial treatment for empiric therapy and specific infections

2 Copyright 2008 Society of Critical Care Medicine Case Study 75-year-old man with altered mental status and productive cough for 2 days BP 110/70 mm Hg, HR 110/min, RR 20/min, T  F (39  C) SpO 2 92% on 2 L/min oxygen by cannula Does he have sepsis or severe sepsis?

3 Copyright 2008 Society of Critical Care Medicine Terminology Sepsis: Systemic manifestations of infection Severe sepsis: Sepsis with organ dysfunction, hypoperfusion, or hypotension Septic shock: Sepsis with arterial hypotension, despite fluid resus- citation, with organ dysfunction

4 Copyright 2008 Society of Critical Care Medicine Case Study 75-year-old man with altered mental status and productive cough for 2 days BP 110/70 mm Hg, HR 110/min, RR 20/min, T  F (39  C) SpO 2 92% on 2 L/min oxygen by cannula What information is needed to determine if he has an infection?

5 Copyright 2008 Society of Critical Care Medicine Diagnosis of Infection History  Epidemiology: acquired in community, long-term care facility, or hospital  Predisposing factors Clinical manifestations  Systemic  Site-specific

6 Copyright 2008 Society of Critical Care Medicine Diagnosis of Infection Laboratory tests  Suggest infection  Assess organ function Microbiologic tests  Stains: immediately available  Cultures: delayed results Radiology

7 Copyright 2008 Society of Critical Care Medicine Case Study 75-year-old man with altered mental status and productive cough Lives at home, no recent hospital stay BP 110/70 mm Hg, HR 110/min, RR 20/min, T  F (39  C) SpO 2 92% on 2 L/min oxygen by cannula What interventions should be instituted?

8 Copyright 2008 Society of Critical Care Medicine Case Study 23-year-old woman in ICU after motor vehicle accident Intubated for 4 days with pulmonary contusions Now with fever,  WBC count, worsening hypoxemia What is the likely source of infection? What factors influence the choice of antimicrobial agents for this patient?

9 Copyright 2008 Society of Critical Care Medicine Antimicrobial Therapy Suspected pathogen and site of infection Gram stain results Assessment for antimicrobial resistance Comorbid conditions

10 Copyright 2008 Society of Critical Care Medicine Case Study What antimicrobial agent(s) would be appropriate for this patient? 23-year-old woman in ICU after motor vehicle accident Intubated for 4 days with pulmonary contusions Now with fever,  WBC count, worsening hypoxemia

11 Copyright 2008 Society of Critical Care Medicine Pneumonia Community-acquired (immunocompetent)  -lactam + macrolide or fluoroquinolone  Clindamycin for aspiration Community-acquired (immunocompromised)  Trimethoprim-sulfamethoxazole  Antifungal agent

12 Copyright 2008 Society of Critical Care Medicine Pneumonia Nosocomial and ventilator- associated  Cephalosporin (3 rd /4 th generation),  -lactam/  -lactamase combination, or carbapenem +  Fluoroquinolone or amino- glycoside  Vancomycin or linezolid for S. aureus  2 antipseudomonal agents if Pseudomonas suspected

13 Copyright 2008 Society of Critical Care Medicine Antimicrobial Therapy 22-year-old college student with possible meningitis 48-year-old renal transplant recipient with possible meningitis 35-year-old with traumatic brain injury and ventriculostomy 4 days ago who has fever and worsening mental status

14 Copyright 2008 Society of Critical Care Medicine Antimicrobial Therapy 75-year-old with bicuspid aortic valve and suspected endocarditis 35-year-old with a tunneled dialysis catheter with fever, hypo- tension, and purulent discharge at catheter site 68-year-old with abdominal pain, fever, and diffuse guarding and rebound tenderness

15 Copyright 2008 Society of Critical Care Medicine Antimicrobial Therapy 32-year-old pregnant woman with fever, vomiting, tachycardia, and suspected pyelonephritis 45-year-old diabetic with erythema and pain over right chest and shoulder

16 Copyright 2008 Society of Critical Care Medicine Antimicrobial Therapy 28-year-old with Hodgkin’s lymphoma who develops neutropenia, fever, and hypotension after chemotherapy 85-year-old with a recent 3-week hospital stay for urosepsis is now admitted with altered mental status, elevated white blood cell count and CT scan showing pancolitis

17 Copyright 2008 Society of Critical Care Medicine Questions?

18 Copyright 2008 Society of Critical Care Medicine Key Points Fever is the most common finding that raises suspicion of infection Cultures should ideally be obtained before antibiotics are initiated Antimicrobial therapy depends on suspected pathogen, site of infection, Gram stain results, resistance, and comorbidities Antimicrobial therapy should be instituted immediately when meningitis is suspected

19 Copyright 2008 Society of Critical Care Medicine Key Points S. pneumoniae is the most common pathogen in severe community-acquired pneumonia Resistant Gram-negatives and S. aureus frequently cause hospital-acquired pneumonia Bactericidal agents, high levels, and long- term therapy are needed for endocarditis Suspected intra-abdominal infection requires the involvement of a surgeon

20 Copyright 2008 Society of Critical Care Medicine Key Points Necrotizing fasciitis requires surgical debridement and antimicrobial therapy Broad-spectrum therapy is indicated in immunocompromised patients with fever Fungal infection should be considered in the presence of predisposing factors