When to Refer to an Infectious Disease Specialist
Refer patients with severe or complex diabetic foot infections, complicated infective endocarditis, Staphylococcus aureus bacteremia, treatment failure after 3-5 days of appropriate therapy, infections requiring complex antibiotic regimens, or those caused by multidrug-resistant organisms to an infectious disease specialist. 1, 2
Mandatory Referral Situations
Severe or Complex Infections
All patients with complicated infective endocarditis should be evaluated early by a multidisciplinary "Endocarditis Team" that includes an ID specialist, particularly when heart failure, abscess formation, or embolic complications are present 2
Severe diabetic foot infections (IWGDF/IDSA classification 4/Severe) with systemic inflammatory response syndrome (SIRS) criteria—temperature >38°C or <36°C, heart rate >90 beats/min, respiratory rate >20 breaths/min, or WBC >12,000/mm³ or <4,000/mm³—warrant ID consultation 1
Moderate diabetic foot infections with complicating features such as severe peripheral arterial disease, lack of home support, or inability to comply with outpatient treatment require ID input 1
Staphylococcus aureus bacteremia should prompt ID consultation, as this has been shown to improve outcomes in sepsis and septic shock 2
Treatment Failure
Patients failing to improve after 3-5 days of appropriate empiric therapy or worsening after 48-72 hours warrant ID consultation 2
Acute bacterial rhinosinusitis patients who are seriously ill, immunocompromised, continue to deteriorate despite extended antimicrobial courses, or have recurrent episodes with clearing between bouts should be referred 2
Diabetic foot infections not responding to outpatient therapy may need hospitalization and ID consultation 1
Resistant or Unusual Pathogens
Infections caused by multidrug-resistant organisms or fungi necessitate ID input for complex antibiotic regimen management 2
Previously treated infections or those caused by antibiotic-resistant pathogens, especially in diabetic foot infections, benefit from ID specialist involvement 1, 2
Empiric antifungal therapy consideration in critically ill patients with risk factors requires ID consultation to guide appropriate agent selection 2
Immunocompromised Patients
All people living with HIV diagnosed with cancer should be referred to an HIV specialist if they don't already have one, with consultation strongly recommended for managing opportunistic infections and drug-drug interactions 2
Patients starting TNF-α inhibitors or other immunosuppressive biologics, especially those with HIV requiring highly active antiretroviral therapy (HAART), should have ID referral considered on a case-by-case basis 2
Suspected opportunistic infections in patients with CD4+ counts <200 cells/μL should prompt ID referral 2
Device-Related and Specialized Infections
Patients with prosthetic devices and suspected infection should be referred to an ID specialist 2
Infections requiring prolonged intravenous antibiotic therapy or outpatient parenteral antimicrobial therapy (OPAT) planning need ID specialist involvement 2
Hepatitis B or C co-infection requiring coordination of antiviral therapy warrants ID referral 2
Key Management Considerations
Multidisciplinary Coordination
Diabetic foot infections require coordination with endocrinology, vascular surgery, podiatry, and wound care specialists, with ID specialists contributing to antibiotic selection and management of resistant pathogens 1
The "Endocarditis Team" should include ID specialists, microbiologists, cardiologists, imaging specialists, and cardiac surgeons meeting regularly to discuss cases and surgical decisions 2
Clinicians without adequate training in wound debridement should seek consultation from more-qualified clinicians, especially when extensive procedures are required 1
Severity Assessment Tools
For community-acquired pneumonia, use the CRB-65 score (Confusion, Respiratory rate >30/min, Blood pressure <90/60 mmHg, age ≥65 years) to guide hospital referral decisions 1
- Score 0: Home treatment
- Score 1-2: Consider hospital referral (particularly score 2)
- Score 3-4: Urgent hospital referral 1
Bilateral chest signs of pneumonia warrant hospital referral regardless of CRB-65 score 1
Hypoxemia (SaO₂ <92% or PaO₂ <8 kPa) regardless of FiO₂ is an adverse prognostic feature requiring hospital assessment 1
Hospital Admission Criteria
Severe infections with features including confusion, drowsiness, temperature <35°C or ≥40°C, cardiac frequency ≥125 beats/min, respiratory frequency ≥30 breaths/min, cyanosis, or blood pressure <90/60 mmHg require hospitalization 1
Biological criteria for hospital management include leukopenia (<4,000 WBC/mL) or severe leukocytosis (>20,000 WBC/mL), anemia (hemoglobin <9 g/100 mL), renal impairment (serum urea >7 mM), PaO₂ <60 mmHg or PaCO₂ >50 mmHg on room air, or acidosis (pH <7.3) 1
Multilobar involvement, pleural effusion, or cavitation on chest radiograph indicates need for hospital management 1
Common Pitfalls to Avoid
Delayed referral to ID specialists should be avoided, as early ID involvement in complicated infections improves outcomes, including reduced mortality in candida bloodstream infections 2, 3
ID specialists can navigate complex drug-drug interactions, particularly in patients on antiretroviral therapy, immunosuppressants, or multiple medications—don't attempt to manage these alone 2
Severity assessment tools do not replace clinical judgment—a patient's social circumstances, ability to comply with treatment, and home support must always be considered 1
Clinicians unfamiliar with pressure off-loading or special dressing techniques should consult foot wound care specialists when these are required 1
Providers in communities with inadequate access to specialists should consider devising systems (e.g., telemedicine) to ensure expert input on managing their patients 1