What information should be included when referring a patient with hospital-acquired pneumonia (HAP) and potential underlying conditions such as diabetes, heart disease, or chronic obstructive pulmonary disease (COPD) to an infectious disease consultant?

Referring a Patient with Hospital-Acquired Pneumonia to an Infectious Disease Consultant

When referring a patient with suspected or confirmed hospital-acquired pneumonia (HAP) to an infectious disease consultant, provide a comprehensive clinical summary that includes timing of pneumonia onset, severity indicators, risk factors for multidrug-resistant organisms, microbiological data, current antibiotic therapy, and underlying comorbidities—this information enables the consultant to rapidly assess appropriateness of empirical coverage and need for diagnostic or therapeutic modifications. 1

Essential Clinical Information to Include

Timing and Classification

• Date of hospital admission and date of pneumonia onset (HAP is defined as pneumonia occurring ≥48 hours after admission that was not incubating at time of admission) 1, 2
• Specify if early-onset (<5 days of hospitalization) or late-onset (≥5 days), as this predicts likely pathogens—early HAP typically involves methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae, while late-onset HAP more commonly involves multidrug-resistant organisms 1, 2, 3
• Document if patient is mechanically ventilated and duration of ventilation (ventilator-associated pneumonia develops after ≥48 hours of mechanical ventilation) 1, 2

Severity Assessment and Clinical Status

• Vital signs at presentation: temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation 1
• Oxygenation status: PaO₂, PaCO₂ if available, oxygen requirements, and whether patient requires mechanical ventilation 1
• Mental status changes: confusion, drowsiness, or altered consciousness 1
• Signs of sepsis or shock: hypotension (BP <90/60 mmHg), tachycardia (>125 beats/min), or evidence of end-organ dysfunction 1

Risk Factors for Multidrug-Resistant Pathogens

• Recent antibiotic exposure (within past 90 days, especially within 2-4 weeks) increases risk for resistant organisms including penicillin-resistant S. pneumoniae 1
• Prior hospitalization within past 90 days, particularly within 2-4 weeks (associated with gram-negative enteric bacilli) 1
• Duration of current hospitalization (prolonged stays >5 days increase MDR risk) 2, 3
• ICU admission and duration of ICU stay 1, 3
• Presence of invasive devices: endotracheal tube, central venous catheter, urinary catheter 4
• Recent surgery or endotracheal intubation (associated with radiologically confirmed HAP) 4

Underlying Comorbidities

• Diabetes mellitus (increases risk for S. pneumoniae, S. aureus, H. influenzae, and gram-negative enteric bacilli) 1
• Chronic obstructive pulmonary disease (COPD) (increases risk for S. pneumoniae, S. aureus, H. influenzae, and gram-negative bacilli) 1
• Cardiovascular disease (increases risk for S. pneumoniae and other typical pathogens) 1
• Chronic liver or renal failure 1
• Neurological diseases that may predispose to aspiration 1
• Immunosuppression status (though these guidelines focus on immunocompetent patients) 1

Laboratory and Radiological Data

• Complete blood count: leukopenia (<4,000 WBC/mL) or severe leukocytosis (>20,000 WBC/mL) 1
• Renal function: serum urea and creatinine (impairment defined as urea >7 mM or creatinine >1.2 mg/dL) 1
• Arterial blood gas: PaO₂ <60 mmHg or PaCO₂ >50 mmHg on room air, pH <7.3 1
• Inflammatory markers: C-reactive protein, lactate dehydrogenase, creatinine kinase 1
• Chest radiograph findings: presence of new or progressive infiltrates, multilobar involvement, pleural effusion, or cavitation 1
• Coagulation studies if disseminated intravascular coagulation suspected 1

Microbiological Information

• Respiratory culture results (sputum, endotracheal aspirate, or bronchoalveolar lavage)—a pathogen is identified in approximately 70% of suspected HAP cases 1, 2
• Blood culture results 1
• Antibiotic susceptibility patterns of any isolated organisms 1
• Local antibiogram data if available, as bacteriology varies between hospitals and time periods 1
• Note that HAP is polymicrobial in 30-50% of cases 1, 3

Current and Prior Antibiotic Therapy

• Current empirical antibiotic regimen with doses and duration 1
• Previous antibiotic courses during this hospitalization 1
• Clinical response to current therapy: improvement, no change, or deterioration 1
• Time from antibiotic initiation to consultation (delayed appropriate therapy increases mortality) 1

Specific Risk Factors for Pseudomonas aeruginosa

If present, these warrant combination antipseudomonal therapy 1, 3:

• Structural lung disease (bronchiectasis, cystic fibrosis)
• Recent broad-spectrum antibiotic use
• Malnutrition
• Prior Pseudomonas colonization or infection

Common Pitfalls to Avoid

Diagnostic Accuracy Issues

• Over-diagnosis of HAP: In ward-level practice, HAP diagnosis may be inaccurate in 35% of cases when objective radiological criteria are applied—ensure new or progressive infiltrates are documented on chest radiograph 4
• Distinguishing colonization from infection: Respiratory tract cultures may represent colonization rather than true infection, particularly in mechanically ventilated patients 5
• Low sensitivity of clinical signs: Clinical symptoms alone have poor sensitivity and specificity for pneumonia diagnosis outside the hospital setting 1

Treatment Considerations

• Monotherapy for Pseudomonas: When P. aeruginosa is implicated, monotherapy is associated with rapid resistance evolution and high clinical failure rates—combination therapy is essential 1, 3
• Broad-spectrum overuse: Empirical broad-spectrum combination antibiotics in uninfected patients can increase mortality—accurate diagnosis is critical 5
• Delayed appropriate therapy: Failure to initiate prompt appropriate therapy is consistently associated with increased mortality 1

Documentation Specifics

• Avoid vague terminology: Instead of "respiratory distress," specify respiratory rate (e.g., 32 breaths/min), oxygen requirement (e.g., 6L nasal cannula), and PaO₂ values 1
• Quantify severity markers: Document specific values for temperature, white blood cell count, creatinine, and blood pressure rather than descriptive terms 1
• Include negative findings: If sputum culture was attempted but not obtained (only 24.7% of HAP patients have sputum successfully cultured), document this 4