What is the appropriate evaluation and management for a 72‑year‑old man with three days of high‑grade fever (102‑103 °F), a single episode of rigor, and severe generalized muscle weakness without cough or cold?

Evaluation and Management of a 72-Year-Old Man with High-Grade Fever, Rigor, and Severe Muscle Weakness

Immediate Clinical Assessment

This patient requires urgent evaluation for serious bacterial infection with immediate blood cultures followed by empirical broad-spectrum antibiotics, as high-grade fever with rigors in an elderly patient indicates bacteremia until proven otherwise. 1

Critical Initial Actions

• Obtain blood cultures immediately before any antibiotics – this is essential as prior antibiotic administration is a major cause of culture-negative infections and obscures diagnosis 2
• Start empirical broad-spectrum intravenous antibiotics within 1 hour if sepsis is suspected based on vital signs (hypotension, tachycardia, altered mental status) 1, 2
• Measure core temperature accurately using rectal, bladder, or esophageal thermometry if available, as these are more reliable than oral or tympanic measurements in critically ill elderly patients 1

Key Historical Elements to Obtain Immediately

• Travel history within the past 10 days – median incubation for serious infections like SARS is 5 days (range 2-10 days) 2
• Exposure to sick contacts – particularly respiratory infections in household members 2
• Complete medication list – drug-induced fever typically manifests 8-21 days after medication initiation and can present with myalgias 2
• Presence of indwelling devices (catheters, prosthetic joints, pacemakers) – common sources of bacteremia 2
• Recent dental procedures or poor oral hygiene – strongly associated with bacteremia and endocarditis 2
• Underlying conditions including diabetes, heart valve abnormalities, vascular grafts, immunosuppression 2
• Animal contact or unpasteurized dairy consumption – increases risk for Q fever and brucellosis which present with fever and severe myalgias 2

Physical Examination Priorities

Rigors specifically indicate bacteremia and warrant aggressive infectious workup. 1 Focus examination on:

• Vital signs every 2-4 hours including blood pressure, heart rate, respiratory rate, oxygen saturation 1
• Neurologic assessment – altered consciousness or focal signs mandate immediate lumbar puncture after imaging to exclude CNS infection 1, 2
• Cardiovascular examination – new murmurs suggest endocarditis 2
• Skin examination – look for rashes, eschars, or lesions that may indicate specific infections 2
• Respiratory examination – auscultate for rales suggesting pneumonia or pulmonary edema 1
• Musculoskeletal examination – assess for joint swelling or focal tenderness suggesting septic arthritis 2

Diagnostic Workup

Essential Laboratory Tests

• Blood cultures (at least 2 sets from different sites) before antibiotics 1, 2
• Complete blood count with differential – note that leukocytosis may be absent in up to 75% of elderly patients with serious infection, and lymphopenia or leukopenia can occur 1, 3
• Comprehensive metabolic panel including creatinine, liver enzymes, electrolytes 1
• C-reactive protein and procalcitonin – elevated levels support bacterial infection 1
• Lactate level – elevated lactate indicates tissue hypoperfusion and sepsis 1
• Creatine kinase and myoglobin – to assess for rhabdomyolysis given severe muscle weakness 1
• Urinalysis and urine culture – urinary tract infections are common causes of fever in elderly patients 2

Imaging Studies

• Chest X-ray – obtain even without respiratory symptoms, as pneumonia may present atypically in elderly patients 1, 3
• Additional imaging based on localizing symptoms – CT abdomen/pelvis if abdominal symptoms, echocardiography if new murmur or suspected endocarditis 1, 2

Respiratory Viral Testing Considerations

If respiratory symptoms develop, collect nasopharyngeal swab within 7 days of symptom onset – sensitivity decreases significantly after 7 days, and serological testing becomes more appropriate 4. However, this patient currently lacks cough or cold symptoms, making respiratory panel testing lower priority than bacterial workup 4.

Management Approach

Empirical Antibiotic Therapy

Initiate broad-spectrum antibiotics immediately after blood cultures if patient shows signs of sepsis (hypotension, tachycardia, altered mental status, or persistent fever >38.3°C with rigors) 1, 2. The specific regimen should cover:

• Gram-positive organisms including MRSA if risk factors present (recent hospitalization, indwelling devices) 1
• Gram-negative organisms including Pseudomonas if immunocompromised or recent healthcare exposure 1
• Consider vancomycin plus piperacillin-tazobactam or a carbapenem as initial empirical therapy pending culture results 1

Supportive Care

• Intravenous fluid resuscitation – administer 250-500 mL boluses of normal saline or lactated Ringer's if hypotensive 1
• Acetaminophen for fever control – helps patient comfort and reduces metabolic demands 1
• Oxygen supplementation if saturation <92% on room air 1
• Monitor intake/output strictly every 8 hours 1

Special Considerations for Muscle Weakness

Severe muscle weakness in the context of fever requires evaluation for both infectious and non-infectious causes:

• Assess for rhabdomyolysis – check CK, myoglobin, and urine for myoglobinuria 1
• Consider viral myositis – influenza and other viral infections can cause severe myalgias 5
• Evaluate for drug-induced myopathy – particularly if patient takes statins or other myotoxic medications 2
• Rule out electrolyte abnormalities – hypokalemia, hypophosphatemia can cause weakness 1

Critical Pitfalls to Avoid

• Do not delay antibiotics waiting for culture results if patient appears septic – mortality increases with each hour of delay 1, 2
• Do not assume normal white blood cell count excludes serious infection – elderly patients frequently have normal or low WBC despite bacteremia 3
• Do not attribute fever solely to viral illness without excluding bacterial infection – rigors strongly suggest bacteremia 1
• Do not start empirical antibiotics for undefined fever without obtaining blood cultures first – this is the leading cause of culture-negative infections 2
• Do not overlook drug-induced fever – particularly if symptoms began 8-21 days after starting new medication 2

Infection Control Measures

Notify infection control department immediately if patient meets criteria for highly pathogenic infection (fever ≥38°C with epidemiological risk factors such as recent travel to endemic areas) 6. Implement:

• Droplet precautions until bacterial pneumonia or influenza excluded 6
• Contact precautions if diarrhea present or C. difficile suspected 6
• Maintain list of all healthcare workers with patient contact for potential exposure tracking 6

Monitoring Parameters

• Vital signs every 2-4 hours including temperature, blood pressure, heart rate, respiratory rate, oxygen saturation 1
• Neurologic assessment every 8 hours – watch for altered mental status suggesting CNS infection or septic encephalopathy 1
• Daily weight and strict intake/output to assess fluid status 1
• Repeat laboratory tests in 24-48 hours including CBC, metabolic panel, lactate to assess response to therapy 1