Case Presentation: An 87-year-old female with congestive heart failure (CHF), coronary artery disease, atrial fibrillation, COPD, and chronic kidney disease presented with 3-day-history of diarrhea, worsened dyspnea, leg swelling and weight gain. Vitals signs were temperature 38.3 C, pulse 104, respiration 20-25 and blood pressure 112/46. Examination was significant for bilateral crackles in lungs, irregular heartbeat with systolic murmur, 3+leg edema, and elevated JVD. Abdomen was mildly distended with hypo-active bowel sounds, but without tenderness. Laboratory work up was significant for WBC 10.7, INR 1.8, BUN 68, creatinine 1.6 and BNP 3467. Chest-x-ray showed interstitial edema with bilateral pleural effusions. She was admitted for acute on chronic CHF, and diarrhea in the setting of fever, tachypnea, tachycardia and leukocytosis. Treatment was initiated with diuresis, fluid restriction, oxygen and Ceftriaxone with Metronidazole. She also underwent therapeutic thoracentesis bilaterally. Aspirin, metoprolol, atorvastatin and Warfarin were resumed. Despite treatment, patient remained tachycardic and had multiple episodes of hypotension. Antibiotics were changed to ampicillin and sulfamethoxazole-trimethoprim (for synergy) when blood and pleural fluid cultures returned positive for Listeria monocytogenes. No stool study was obtained, as she had no further diarrhea. Echocardiogram showed decreased right ventricular systolic function with pulmonary hypertension and tricuspid regurgitation. Unfortunately CHF was refractory to scheduled intravenous furosemide boluses, and also to continuous bumetanide drip; no improvement occurred with addition of Dobutamine drip, and hypoxemia worsened despite oxygen supplementation by high flow nasal cannula and therapy with BiPAP. Faced with need for mechanical ventilation, patient and family opted to discontinue active interventions and transition to comfort care. Patient’s condition deteriorated further and she expired less than 48 hours after.
Discussion: Listeria is an aerobic and facultative anaerobic gram-positive rod that exhibits characteristic tumbling motility by light microscopy. On gram stain it may resemble pneumococci or diphteroids, or may be gram variable and be confused with Haemophilus spp. Most infection in adults is from oral ingestion and subsequent intestinal mucosal penetration and systemic infection. It causes self-limited febrile diarrheal illness in immunocompetent people, but invasive disease in pregnant, neonates, elderly and immunocompromised people. Treatment for invasive disease is with ampicillin, penicillin, gentamicin or sulfamethoxazole-trimethoprim. Cephalosporins account for 90% of inadequate treatment. Duration of treatment for bacteremia is 2 weeks in immunocompetent patients, and 3-6 weeks in immunocompromised patients.
Conclusions: Invasive disease (including bacteremia and CNS infection) by Listeria monocytogenes is uncommon but mortality is high without treatment, especially in patients with other comorbidities, so early diagnosis and initiation of appropriate antibiotics is pertinent. There is no way to differentiate listeria infection from other febrile illnesses without blood cultures, so high index of suspicion must be maintained in the group at risk as noted above. Since listeria may look like diphteroids on gram stain, preliminary report of diphteroids on gram stain in at risk population should not be considered a contamination.