Case Presentation: The patient is a 57-year-old male with a past medical history of coronary artery disease complicated by ventricular fibrillation cardiac arrest and heart failure with reduced ejection fraction, status post implantable cardioverter defibrillator (ICD) placement, as well as recently relapsed intravenous heroin use disorder. He was admitted for replacement of his ICD battery and found to have subacute progressive dyspnea on exertion, chest pain, and orthopnea. On arrival, he was tachycardic to 105 beats per minute with other vital signs within normal limits. Exam revealed lower extremity pitting edema bilaterally. No murmur or peripheral embolic phenomena were appreciated. Labs showed anemia and an elevated white cell count with bandemia. Serial electrocardiograms and cardiac enzymes did not show evidence of ischemia. Computed tomography revealed new bilateral lung consolidations and left upper lobe cavitation. A transthoracic echocardiogram showed mobile echodensities on the ICD wire. Blood cultures grew Enterobacter cloacae, ultimately treated with cefepime. Further history revealed subjective fevers and re-use of cotton filters to inject heroin. The patient underwent ICD extraction with negative cultures originating from the leads. The patient remains hospitalized with his course complicated by sepsis, respiratory failure necessitating intubation and multiple nosocomial infections.
Discussion: Non-HACEK (species other than Haemophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella) gram-negative bacillus endocarditis is rare, accounting for 1-2% of endocarditis cases. Although historically considered a disease of injection drug users, it is primarily a healthcare-associated infection more common in the presence of prosthetic valves, permanent pacemakers, or ICDs. However, Enterobacter specifically has been found to be associated with intravenous drug use. First described in 1975, “cotton fever” is a transient elevation in body temperature (1-2oC) occurring minutes after injecting trace amounts of drugs extracted from re-used cotton filters. The gram-negative bacillus Enterobacter genus, and in particular the endotoxins it releases, has been implicated in its pathophysiology. The first study to implicate any bacterial species other than Enterobacter agglomerans in cotton fever was published in late 2019. Similar to our patient, the study described a case of cotton fever complicated by infective endocarditis and associated with Enterobacter asburiae, a member of the Enterobacter cloacae complex. Both monotherapy and combination antibiotic therapy have been utilized in Enterobacter endocarditis, without significant differences in mortality or eventual surgical intervention.
Conclusions: Enterobacter endocarditis is exceedingly rare and has been found to be associated with intravenous drug use. Detailed history can aid in identifying the microbiologic etiology of infectious endocarditis, such as infection with non-HACEK species, especially in patients with implanted endovascular devices.