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.

De Novo Cytomegalovirus Colitis in a Donor-Seronegative/Recipient-Seronegative Kidney Transplant Recipient.

Cytomegalovirus (CMV) is one of the most frequent microbes linked with kidney transplant recipients. CMV infection is typically classified as CMV virus isolation in any body fluid or specimen. We present a 43-year-old man who underwent a deceased donor kidney transplant with CMV donor-seronegative and recipient-seronegative (CMV D-/R-) status and completed three months of CMV prophylaxis with high-dose acyclovir given his low-risk status. He was admitted for complaints of profuse watery diarrhea and persistent fevers lasting one week in duration. His infectious workup led to a CMV quantitative nucleic acid amplification test (QNAT) polymerase chain reaction (PCR) of 239,977 IU/mL with a biopsy-proven diagnosis of invasive CMV colitis. He was treated inpatient with intravenous ganciclovir for two weeks and then de-escalated to oral valganciclovir until achieving viremia resolution with undetectable CMV QNAT PCR as an outpatient. This case illustrates the importance of the changing epidemiology and clinical presentation of CMV disease in solid organ transplant (SOT) recipients in an era of new immunosuppression regimens and improved CMV disease detection in the early post-transplant period.

Cat Scratch Disease: An Unusual Case of Right Inguinal Lymphadenitis Due to Bartonella henselae.

Cat scratch disease (CSD) is caused by a bacterial infection due to Bartonella henselae and is associated with young cats and kittens. CSD commonly occurs as regional lymphadenitis in the setting of subacute regional lymphadenopathy predominantly in children and young adults. The prognosis for immunocompetent patients is favorable with complete recovery, however, immunocompromised adults can progress to life-threatening complications such as neuroretinitis, osteomyelitis, and bacillary angiomatosis. B. henselae is transmitted from cats to humans through scratching or biting when located on the cat's claws or oral cavity. In 1% of diagnosed cases, patients developed this disease without ever receiving an animal scratch.  We present a case of a 29-year-old immunocompetent male developing severe right inguinal pain with concern for an incarcerated inguinal hernia. He reported exposure to a vaccinated six-month-old kitten but denied any recent scratches or bites. His infectious workup revealed right inguinal lymphadenitis on CT imaging and subsequent lymph node biopsy confirmed a diagnosis of CSD. He was treated with a short course of oral doxycycline for CSD and opioids for pain management. This case illustrates the importance of thorough complete history and physical taking even in immunocompetent patients and early recognition with prompt targeted treatment of Bartonella lymphadenitis to prevent unfavorable outcomes.