Does a resident colonized with ESBL (Extended-Spectrum Beta-Lactamase) producing organisms, with leukocytosis (leukocyte count > 100,000), meet McGeer's criteria?

McGeer's Criteria Assessment for ESBL-Colonized Resident

This resident does NOT meet McGeer's criteria for infection based on the information provided. ESBL colonization alone, even with marked leukocytosis, is insufficient without specific clinical signs and symptoms of active infection at a defined anatomical site.

Understanding McGeer's Criteria Framework

McGeer's criteria are surveillance definitions designed specifically for long-term care facilities to distinguish colonization from active infection. These criteria require:

• Specific clinical signs/symptoms at a defined anatomical site (respiratory, urinary, skin/soft tissue, gastrointestinal) 1
• Laboratory or radiographic confirmation when applicable 1
• Not just laboratory abnormalities alone 1

Why This Case Does Not Meet Criteria

ESBL Colonization vs. Infection

• Colonization means the organism is present but not causing active disease 2, 3
• ESBL-producing organisms can colonize the gastrointestinal tract, urinary tract, or skin without causing infection 2
• Treatment is not indicated for colonization alone, even in the presence of laboratory abnormalities 1

Leukocytosis Interpretation

The leukocyte count >100,000/mm³ is extremely elevated and warrants investigation, but:

• Leukocytosis alone does not define infection under McGeer's criteria 1
• An elevated total band neutrophil count ≥1,500 cells/mm³ has the highest likelihood ratio (14.5) for bacterial infection, but this must be correlated with clinical symptoms 4, 5
• Left shift ≥16% band neutrophils has a likelihood ratio of 4.7 for bacterial infection, but again requires clinical correlation 4, 6
• In the absence of fever, specific clinical manifestations of focal infection, or left shift, additional diagnostic tests may not be indicated 4

What Is Missing for McGeer's Criteria

To meet McGeer's criteria, this resident would need at least one of the following:

Respiratory Tract Infection Criteria

• Respiratory rate ≥25 breaths/min 1
• New or increased cough 1
• New or increased sputum production 1
• Oxygen saturation <90% or reduction ≥3% from baseline 1
• New abnormality on chest examination 1
• Chest radiograph showing new infiltrate 1

Urinary Tract Infection Criteria

• Dysuria, urgency, frequency, or suprapubic pain 1
• Fever ≥100°F (37.8°C) or leukocytosis with no other identified source 1
• Acute change in mental status with no other identified cause 1
• Plus pyuria and positive urine culture 1

Skin/Soft Tissue Infection Criteria

• Purulent drainage from wound or skin 1
• New or increasing heat, redness, swelling, or tenderness 1
• Fever with wound present 1

Gastrointestinal Infection Criteria

• Diarrhea (≥3 loose/watery stools in 24 hours) 1
• Vomiting 1
• Abdominal pain or tenderness 1

Critical Diagnostic Approach

Given the extreme leukocytosis (>100,000/mm³), immediate evaluation is essential:

1. Obtain complete blood count with manual differential to assess for:

   • Absolute band count ≥1,500 cells/mm³ (highest diagnostic accuracy for bacterial infection) 4, 6
   • Band percentage ≥16% (significant left shift) 4, 6
   • Peripheral blood smear to rule out leukemia or leukemoid reaction 5

2. Perform focused clinical assessment for:

   • Temperature (fever ≥100°F or hypothermia <96.8°F) 1
   • Respiratory symptoms and pulse oximetry 1
   • Urinary symptoms 1
   • Skin/wound examination 1
   • Mental status changes 1
   • Gastrointestinal symptoms 1

3. Consider site-specific testing based on clinical findings:

   • Blood cultures if bacteremia suspected (hypotension, severe illness) 1, 5
   • Urinalysis and culture if urinary symptoms present 5, 6
   • Chest radiograph if respiratory symptoms or hypoxemia 1, 6
   • Stool studies if diarrhea present 6

Important Caveats

Leukocytosis of This Magnitude Requires Investigation

• Leukocyte count >100,000/mm³ is extreme and unusual for typical bacterial infection 1
• This level raises concern for:
  • Leukemoid reaction (extreme reactive leukocytosis mimicking leukemia) 5
  • Hematologic malignancy (chronic myeloid leukemia, acute leukemia) 5
  • Severe systemic infection with marked inflammatory response 1

Older Adults in Long-Term Care

• Fever may be absent in up to 15% of bacteremic older persons 1
• Nonspecific symptoms (lethargy, confusion, falls, incontinence) may be the only manifestations of serious infection 1
• Lower baseline body temperature means fever threshold is lower (≥2°F increase from baseline or ≥100°F) 1

ESBL-Specific Considerations

• If active infection is documented, carbapenems are the treatment of choice for serious ESBL infections 1, 2
• Modifications to empirical therapy should be considered for patients colonized with ESBL organisms if infection develops, particularly if unstable 1
• Piperacillin-tazobactam may be considered for ESBL urinary tract infections based on recent evidence 7

Common Pitfalls to Avoid

• Do not treat ESBL colonization with antibiotics - this promotes further resistance without clinical benefit 1, 2
• Do not ignore extreme leukocytosis - counts >100,000/mm³ require hematologic evaluation regardless of infection status 5
• Do not rely on automated differential alone - manual differential is essential for accurate band assessment 4, 6
• Do not assume infection based solely on laboratory values - McGeer's criteria require clinical signs/symptoms at a specific anatomical site 1