What is the recommended evaluation and treatment of bacteremia in an older adult with sclerosing mesenteritis who presents with fever, tachycardia, hypotension, leukocytosis, or rapid mental status decline?

Evaluation and Treatment of Bacteremia in Older Adults with Sclerosing Mesenteritis

An older adult with sclerosing mesenteritis presenting with fever, hypotension, tachycardia, leukocytosis, or rapid mental status decline requires immediate blood cultures prior to empiric broad-spectrum antibiotics, with urgent consideration for acute care transfer given the 18-50% mortality rate and the fact that 50% of deaths occur within 24 hours despite appropriate therapy. 1

Immediate Diagnostic Evaluation

Blood Cultures and Source Identification

• Obtain blood cultures immediately before initiating antimicrobial therapy, as this is critical for establishing definitive microbiologic diagnosis and guiding subsequent therapy 1
• Blood cultures are particularly indicated given the presentation with hypotension (shock), leukocytosis, and mental status changes—all high-risk predictors of bacteremia with relative risks of 3.4-15.7 1
• In the context of sclerosing mesenteritis, consider intra-abdominal sources as a potential focus, which accounts for 5% of bacteremias in older adults 1

Source Control Assessment

• Evaluate for intra-abdominal abscess or complications given the underlying sclerosing mesenteritis, as intra-abdominal infections are a leading cause of fever of unknown origin in older adults and require urgent imaging 1
• CT imaging should be obtained urgently if intra-abdominal source is suspected, as complications of GI disease present atypically in older adults with delayed diagnosis leading to increased mortality 1
• Consider that sclerosing mesenteritis itself can be associated with infectious complications, including mycobacterial infections, though this is rare 2

Additional Diagnostic Workup

• Obtain urine culture if urosepsis is suspected (50-55% of bacteremias in older adults originate from urinary tract), along with Gram stain of uncentrifuged urine 1
• Chest radiography if respiratory source suspected (10-11% of bacteremias), particularly if hypoxemia is present 1
• Evaluate skin/soft tissue sources (10% of bacteremias) 1

Empiric Antimicrobial Therapy

Immediate Treatment Initiation

• Start broad-spectrum empiric antimicrobials immediately after blood cultures are obtained, as delay in effective antimicrobial therapy is significantly linked to poor outcomes in critically ill patients with septic shock 1
• The empiric regimen must cover anaerobes and Gram-negative bacteria given the potential intra-abdominal source in the context of sclerosing mesenteritis 1

Antimicrobial Selection Considerations

• Account for risk factors for resistant organisms: healthcare facility exposure, corticosteroid use (relevant if patient has been treated for sclerosing mesenteritis with steroids), organ transplantation, baseline pulmonary/hepatic disease, and prior antimicrobial therapy 1
• Consider quinolone and carbapenem resistance, ESBL-producing bacteria based on local resistance patterns and recent travel history 1
• If intra-abdominal source confirmed, obtain intraperitoneal samples for microbiological evaluation to guide de-escalation 1

Duration of Therapy

• Plan for 3-5 days of antibiotic therapy after adequate source control if source control is achieved 1
• If signs of peritonitis or systemic illness persist beyond 5-7 days, further diagnostic investigation is mandatory 1

Critical Prognostic Factors

High-Risk Features Predicting Mortality

• Hypotension, pulmonary source, and leukocytosis >20,000 cells/mm³ are independent predictors of mortality in nursing home-acquired bloodstream infections 1
• Overall mortality rates for bacteremia in older adults range from 18-50%, with highest rates (up to 50%) for bacteremic pneumonia 1
• 50% of deaths occur within 24 hours of bacteremia diagnosis despite appropriate therapy, emphasizing the need for immediate intervention 1

Atypical Presentations in Older Adults

• Older bacteremic patients are less likely to present with fever or tachycardia but more likely to have acute renal or respiratory failure compared to younger adults 1
• Up to 15% may have "afebrile" bacteremia, particularly if already receiving antimicrobials 1
• Nonspecific symptoms (lethargy, confusion, falls, abdominal pain, nausea, vomiting, incontinence) are frequently the only presenting signs 1

Critical Pitfalls to Avoid

Do Not Attribute Mental Status Changes to Asymptomatic Bacteriuria

• In the presence of fever, hypotension, tachycardia, and leukocytosis, this represents true sepsis/bacteremia requiring treatment—not asymptomatic bacteriuria 3, 4
• The IDSA strongly recommends against treating asymptomatic bacteriuria in older adults with dementia, but this patient has clear systemic signs of infection 3
• The confusion in this clinical context is sepsis-induced delirium, which will reverse with appropriate antimicrobial therapy targeting the underlying infection 4

Do Not Delay Transfer to Acute Care

• Evaluation for intra-abdominal infections should be considered a medical emergency requiring admission to an acute care facility 1
• Given the 50% mortality within 24 hours, there is minimal opportunity for adjusting therapy based on culture results if treatment is delayed 1

Sclerosing Mesenteritis-Specific Considerations

• While sclerosing mesenteritis is relatively benign, it can have a prolonged debilitating course with fatal outcomes in 17% of cases due to complications 5
• Be vigilant for infectious complications, as sclerosing mesenteritis can be associated with or caused by infections including mycobacterial disease 2
• Consider that patients with sclerosing mesenteritis may be on immunosuppressive therapy (corticosteroids, azathioprine, tamoxifen), increasing infection risk and resistance patterns 5, 6, 7