Life-Threatening Infections: Diagnosis and Antimicrobial Therapy Selection.

Life-Threatening Infections: Diagnosis and Antimicrobial Therapy Selection

2 Copyright 2008 Society of Critical Care Medicine

Objectives

Understand and apply terminology specific to life-threatening infectionsList risk factors for development of infection Identify clinical manifestations of life-threatening infections and understand use of laboratory tests in diagnosisDescribe variables used to guide selection of antimicrobial therapy Outline antimicrobial treatment for empiric therapy and specific infections


Case Study

75-year-old man with altered mental status and productive cough for 2 daysBP 110/70 mm Hg, HR 110/min, RR 20/min, T 102.2 F (39 C)SpO2 92% on 2 L/min oxygen by cannula

Does he have sepsis or severe Does he have sepsis or severe sepsis?sepsis?


Terminology

Sepsis: Systemic manifestations of Sepsis: Systemic manifestations of infectioninfection

Severe sepsis: Sepsis with organ Severe sepsis: Sepsis with organ dysfunction, hypoperfusion, or dysfunction, hypoperfusion, or hypotensionhypotension

Septic shock: Sepsis with arterial Septic shock: Sepsis with arterial hypotension, despite fluid resus-hypotension, despite fluid resus-citation, with organ dysfunctioncitation, with organ dysfunction


Case Study

75-year-old man with altered mental status and productive cough for 2 daysBP 110/70 mm Hg, HR 110/min, RR 20/min, T 102.2F (39C)SpO2 92% on 2 L/min oxygen by cannula

What information is needed to What information is needed to determine if he has an infection? determine if he has an infection?


Diagnosis of Infection

History Epidemiology: acquired in

community, long-term care facility, or hospital

Predisposing factorsClinical manifestations Systemic Site-specific


Diagnosis of Infection

Laboratory tests Suggest infection Assess organ functionMicrobiologic tests Stains: immediately available Cultures: delayed resultsRadiology


Case Study

75-year-old man with altered mental status and productive cough Lives at home, no recent hospital stayBP 110/70 mm Hg, HR 110/min, RR 20/min, T 102.2F (39C)SpO2 92% on 2 L/min oxygen by cannula

What interventions should be What interventions should be instituted? instituted?


Case Study

23-year-old woman in ICU after motor vehicle accidentIntubated for 4 days with pulmonary contusions Now with fever, WBC count, worsening hypoxemia

What is the likely source of infection? What is the likely source of infection?

What factors influence the choice of What factors influence the choice of antimicrobial agents for this patient? antimicrobial agents for this patient?


Antimicrobial Therapy

Suspected pathogen and site of infectionGram stain resultsAssessment for antimicrobial resistanceComorbid conditions


Case Study

What antimicrobial agent(s) would What antimicrobial agent(s) would be appropriate for this patient? be appropriate for this patient?

23-year-old woman in ICU after motor vehicle accidentIntubated for 4 days with pulmonary contusions Now with fever, WBC count, worsening hypoxemia


Pneumonia

Community-acquired (immunocompetent) -lactam + macrolide or

fluoroquinolone Clindamycin for aspirationCommunity-acquired (immunocompromised) Trimethoprim-sulfamethoxazole Antifungal agent


Pneumonia

Nosocomial and ventilator-associated Cephalosporin (3rd/4th generation),

-lactam/ -lactamase combination, or carbapenem +

Fluoroquinolone or amino-glycoside

Vancomycin or linezolid for S. aureus

2 antipseudomonal agents if Pseudomonas suspected



22-year-old college student with possible meningitis

48-year-old renal transplant recipient with possible meningitis35-year-old with traumatic brain injury and ventriculostomy 4 days ago who has fever and worsening mental status



75-year-old with bicuspid aortic valve and suspected endocarditis35-year-old with a tunneled dialysis catheter with fever, hypo-tension, and purulent discharge at catheter site68-year-old with abdominal pain, fever, and diffuse guarding and rebound tenderness



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



28-year-old with Hodgkin’s lymphoma who develops neutropenia, fever, and hypotension after chemotherapy85-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


Questions? Questions?


Key Points

Fever is the most common finding that raises suspicion of infectionCultures should ideally be obtained before antibiotics are initiatedAntimicrobial therapy depends on suspected pathogen, site of infection, Gram stain results, resistance, and comorbiditiesAntimicrobial therapy should be instituted immediately when meningitis is suspected


Key Points

S. pneumoniae is the most common pathogen in severe community-acquired pneumoniaResistant Gram-negatives and S. aureus frequently cause hospital-acquired pneumoniaBactericidal agents, high levels, and long-term therapy are needed for endocarditisSuspected intra-abdominal infection requires the involvement of a surgeon


Key Points

Necrotizing fasciitis requires surgical debridement and antimicrobial therapyBroad-spectrum therapy is indicated in immunocompromised patients with feverFungal infection should be considered in the presence of predisposing factors

Life-Threatening Infections: Diagnosis and Antimicrobial Therapy Selection.

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