A Case of Infective Endocarditis Caused by Citrobacter koseri: Unraveling a Rare Pathogen and Dire Outcome.

Citrobacter koseri (formerly classified as Citrobacter diversus) is a gram-negative bacillus (GNB) that occurs as an opportunistic pathogen in neonates and immunocompromised patients. Citrobacter species have been implicated in nosocomial settings leading to infections involving the urinary tract, respiratory tract, liver, biliary tract, meninges, and even in rarer conditions-blood stream infection and infective endocarditis (IE). Gram-negative bacilli are responsible for 3% to 4% of all IE cases and have been traditionally associated with intravenous drug users. Patients with non-HACEK (species other than Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, or Kinglella species) GNB IE have poor clinical outcomes with higher rates of in-hospital mortality and complications. The American Heart Association (AHA) and Infectious Diseases Society of America (IDSA) both recommend the use of combination antibiotic therapy with a beta-lactam (penicillins, cephalosporins, or carbapenems) and either an aminoglycoside or fluoroquinolones for 6 weeks (about 1 and a half months) to treat IE due to non-HACEK GNB. Citrobacter koseri is becoming more recognized due to its inherent resistance to ampicillin and emerging drug resistance to beta lactams and aminoglycosides requiring carbapenem therapy. Our case is of a 75-year-old male with no previously reported history of primary or secondary immunodeficiency disorders who developed C koseri blood stream infection. His infectious work-up revealed mitral valve IE and septic cerebral emboli resulting in ischemic infarcts. This case illustrates the importance of recognizing GNB organisms as rising human pathogens in IE cases even without active injection drug use or nosocomial exposure.

A Rare Case of Persistent Bacteremia: Leadless Micra Pacemaker Endocarditis.

Leadless pacing systems have revolutionized the field of electrophysiology given its low complication rates and almost non-existent rate of infections compared with traditional pacemakers. These devices boast resistance to infections given its unique features; however, as described in this report, device-related infection from these leadless devices is still possible. In patients with leadless pacing system that is persistently bacteremic in the future, evaluation of the device with transesophageal echocardiogram or intracardiac echocardiography should be performed, and if vegetation is noted on the device, device extraction should highly be considered, along with empiric intravenous antibiotics. Lastly, new leadless device should not be re-implanted within 2 weeks of the removal of the infected device to prevent seeding of the new device.

COVID-19 vaccine-associated myocarditis.

Myocarditis is now recognized as a rare complication of coronavirus disease 2019 (COVID-19) mRNA vaccination, particularly in adolescent and young adult males. Since the authorization of the Pfizer-BioNTech™ and Moderna™ mRNA vaccines targeting the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein, the Centers for Disease Control and Prevention (CDC) has reported 1175 confirmed cases of myocarditis after COVID-19 vaccination in individuals ages 30 years and younger as of January 2022. According to CDC data in June 2021, the incidence of vaccine-mediated myocarditis in males ages 12-29 years old was estimated to be 40.6 cases per million second doses of COVID-19 mRNA vaccination administered. Individuals with cases of COVID-19 vaccine-mediated myocarditis typically present with acute chest pain and elevated serum troponin levels, often within one week of receiving the second dose of mRNA COVID-19 vaccination. Most cases follow a benign clinical course with prompt resolution of symptoms. Proposed mechanisms of COVID-19 vaccine myocarditis include molecular mimicry between SARS-CoV-2 spike protein and self-antigens and the triggering of preexisting dysregulated immune pathways in predisposed individuals. The higher incidence of COVID-19 vaccine myocarditis in young males may be explained by testosterone and its role in modulating the immune response in myocarditis. There is limited data on long-term outcomes in these cases given the recency of their occurrence. The CDC continues to recommend COVID-19 vaccination for everyone 5 years of age and older given the greater risk of serious complications related to natural COVID-19 infection including hospitalization, multisystem organ dysfunction, and death. Further study is needed to better understand the immunopathology and long-term outcomes behind COVID-19 mRNA vaccine-mediated myocarditis.

Takotsubo cardiomyopathy: A comprehensive review.

Takotsubo cardiomyopathy (TCM), also known as stress cardiomyopathy, occurs in the setting of catecholamine surge from an acute stressor. This cardiomyopathy mimics acute myocardial infarction in the absence of coronary disease. The classic feature of TCM is regional wall motion abnormalities with characteristic ballooning of the left ventricle. The etiology of the stressor is often physical or emotional stress, however iatrogenic causes of TCM have been reported in the literature. In our review, we discuss medications, primarily the exogenous administration of catecholamines, and a wide array of procedures with subsequent development of iatrogenic cardiomyopathy. TCM is unique in that it is transient and has favorable outcomes in most individuals. Classically, beta-blockers and ACE-inhibitors have been prescribed in individuals with cardiomyopathy; however, unique to TCM, no specific treatment is required other than temporary supportive measures as this process is transient. Additionally, no improvement in mortality or recurrence have been reported in patients on these drugs. The aim of this review is to elucidate on the iatrogenic causes of TCM, allowing for prompt recognition and management by clinicians.

Role of cardiac magnetic resonance imaging in the diagnosis and management of COVID-19 related myocarditis: Clinical and imaging considerations.

There is a growing evidence of cardiovascular complications in coronavirus disease 2019 (COVID-19) patients. As evidence accumulated of COVID-19 mediated inflammatory effects on the myocardium, substantial attention has been directed towards cardiovascular imaging modalities that facilitate this diagnosis. Cardiac magnetic resonance imaging (CMRI) is the gold standard for the detection of structural and functional myocardial alterations and its role in identifying patients with COVID-19 mediated cardiac injury is growing. Despite its utility in the diagnosis of myocardial injury in this population, CMRI's impact on patient management is still evolving. This review provides a framework for the use of CMRI in diagnosis and management of COVID-19 patients from the perspective of a cardiologist. We review the role of CMRI in the management of both the acutely and remotely COVID-19 infected patient. We discuss patient selection for this imaging modality; T1, T2, and late gadolinium enhancement imaging techniques; and previously described CMRI findings in other cardiomyopathies with potential implications in COVID-19 recovered patients.

Wind-bias correction method for narrowband sodium Doppler lidars using iodine absorption spectroscopy.

We present a technique to measure the frequency chirp introduced by the laser pulse amplification process in the transmitter of the Colorado State University sodium lidar system. This chirp causes a systematic radial wind bias that must be removed from the reported wind measurements. An iodine absorption line located near the lidar operating wavelength of 589.16 nm is used for real-time monitoring and measurement of the chirp for the correction of radial wind bias. This technique has been thoroughly characterized in the laboratory and validated by field testing, facilitating simultaneous measurements of temperature and horizontal wind in the mesopause region of the atmosphere (80-105 km).