The Wild West: A Case of Bubonic Plague

To the Editors: We report a 15-year-old female from rural Colorado who presented in septic shock secondary to Yersinia pestis bacteremia and bubonic plague. The case underscores the importance of maintaining high clinical suspicion for this rare but serious zoonotic infection when caring for individuals living in endemic areas and with high-risk exposures to ensure timely empiric antibiotic administration to prevent adverse outcomes. She presented with 1 week of fever, vomiting, diarrhea and a tender inguinal groin mass (Fig. 1A) in the setting of acute hypoxic respiratory failure and hypotensive septic shock. Admission labs were significant for hyperlactatemia (4.17 mmol/L), elevated C-reactive protein (>270 mg/L), acute kidney injury (creatinine 1.78 mg/dL), neutrophilic leukocytosis (white blood cell 48.5 × 109/L, absolute neutrophil count 43.7 × 109/L), hyperferritinemia (>10,000 ng/mL), coagulopathy (platelets 45 × 109/L, prothrombin time 22.5 seconds, partial thromboplastin time 79.9 seconds, fibrinogen 562 mg/dL) and transaminitis (alanine aminotransferase 39 U/L, aspartate aminotransferase 320 U/L). She required vasoactive medications and a humidified high-flow nasal cannula. She lived on a rural cattle ranch, and her family recently adopted a puppy with fleas. Empiric ceftriaxone, linezolid and ciprofloxacin were started.FIGURE 1.: A: Photograph of progressively enlarging right inguinal groin bubo. B: Noncontrast computed tomography abdomen/pelvis of right iliac and inguinal lymphadenopathy with inflammation and fat stranding.Chest radiograph demonstrated bibasilar opacities, interstitial edema and a trace of left pleural effusion. Lower extremity venous duplex Doppler ultrasound demonstrated a nonocclusive thrombus in the right greater saphenous vein. Computed tomography abdomen/pelvis demonstrated right iliac and inguinal lymphadenopathy with a right inguinal node measuring 1.7 × 1.7 × 1.7 cm with extensive adjacent inflammation and fat stranding (Fig. 1B). Blood cultures identified a gram-negative bacillus, raising suspicion for bubonic plague in the context of her clinical presentation. Yersinia pestis was confirmed by blood polymerase chain reaction. Antibiotic therapy was narrowed to intravenous ciprofloxacin monotherapy. She was treated for a total of 14 days. Early clinical suspicion, recognition and empiric treatment of bubonic plague are important, especially when a patient presents with fever and tender regional lymphadenitis.1,2 In the correct clinical context, clinicians should search for buboes on exam, which are painful, fluctuant lymph nodes characteristic of this infection.3 Epidemiologic risk factors such as rural residence in Western states or zoonotic exposures raise suspicion for this diagnosis.4,5 Blood culture typically reveals gram-negative coccobacilli or bacilli with a bipolar appearance.1 Identification can be confirmed via polymerase chain reaction.1,2 If suspicious, initiation of atypical empiric therapies such as fluoroquinolones or tetracyclines is important to optimize clinical outcomes.2 When evaluating a patient with regional lymphadenitis, a broad infectious differential diagnosis must account for common and geographically specific pathogens. Common etiologies include invasive soft tissue infections, most frequently caused by Staphylococcus aureus or Group A beta-hemolytic Streptococcus. In rural settings, consider endemic pathogens such as Y. pestis and Francisella tularensis. If lymphadenopathy is widespread, Rocky Mountain spotted fever and Typhus are possible. Hantavirus may be considered if there is significant pulmonary involvement. The diversity of potential infectious etiologies underscores the need for broad-spectrum empiric antimicrobials, which can subsequently be refined. Bubonic plague should be considered in pediatric patients living in endemic regions with environmental exposures presenting with fever, lymphadenopathy and sepsis. Early recognition is essential for prompt antimicrobial treatment to improve outcomes associated with this potentially fatal but treatable infection.