Lethal Waterhouse-Friderichsen syndrome caused by Capnocytophaga canimorsus in an asplenic patient.

BACKGROUND: Capnocytophaga canimorsus, a Gram-negative rod, belongs to the Flavobacteriaceae family and colonizes the oropharynx of dogs and cats. Infections with C. canimorsus are rare and can induce a systemic infection with a severe course of the disease. So far, only five case reports of C. canimorsus infections associated with Waterhouse-Friderichsen Syndrome (WFS) have been reported with only two of the patients having a history of splenectomy. CASE PRESENTATION: Here, we report a fatal case of WFS due to C. canimorsus bacteremia and mycetal superinfection in a 61-year-old female asplenic patient. Despite extensive therapy including mechanical ventilation, antibiotic coverage with meropenem, systemic corticosteroids medication, vasopressor therapy, continuous renal replacement therapy, therapeutic plasma exchange, multiple transfusions of blood products and implantation of a veno-arterial extracorporeal membrane oxygenation the patient died 10 days after a dog bite. The autopsy showed bilateral hemorrhagic necrosis of the adrenal cortex and septic embolism to heart, kidneys, and liver. Diagnosis of C. canimorsus was prolonged due to the fastidious growth of the bacteria. CONCLUSIONS: The occurrence of a severe sepsis after dog bite should always urge the attending physician to consider C. canimorsus as the disease-causing pathogen. A therapeutic regimen covering C. canimorsus such as aminopenicillins or carbapenems should be chosen. However, despite maximum therapy, the prognosis of C. canimorsus-induced septic shock remains very poor. Asplenic or otherwise immunocompromised patients are at higher risk for a severe course of disease and should avoid exposure to dogs and cats and consider antibiotic prophylaxis after animal bite.

An Infected Bicuspid Aortic Valve, an Anomalous Coronary Artery, and a Dog-Bitten Postman.

Risk factors for infective endocarditis (IE) include congenital heart defects, poor dentition, immunosuppression, or recent instrumentation. The occupational hazard of a dog bite, combined with bicuspid aortic valve (BAV) led to IE. 16S ribosomal DNA was able to pinpoint the causative organism. A healthy 33-year-old postman presented in profound heart failure and sepsis due to aortic regurgitation and an aortic root abscess. He underwent emergency aortic valve replacement and was found to have a BAV and anomalous right coronary artery. Blood cultures remained negative. 16S ribosomal DNA polymerase chain reaction (PCR) revealed the causative organism was Capnocytophaga canimorsus. On review, he recalled receiving a dog bite followed by a febrile illness a few days later. Congenital BAVs may become infected by seemingly innocuous injuries. 16S rDNA PCR is a more sensitive and specific diagnostic test than culture. This case demonstrates its utility in providing appropriate antimicrobial management for IE.

Fatal septic shock due to Capnocytophaga canimorsus bacteremia masquerading as COVID-19 pneumonia - a case report.

BACKGROUND: Capnocytophaga canimorsus (C. canimorsus) infections are rare and usually present with unspecific symptoms, which can eventually end in fatal septic shock and multiorgan failure. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) related coronavirus disease 2019 (COVID-19), on the other hand, is predominantly characterized by acute respiratory failure, although other organ complications can occur. Both infectious diseases have in common that hyperinflammation with a cytokine storm can occur. While microbial detection of C. canimorsus in blood cultures can take over 48 h, diagnosis of SARS-CoV-2 is facilitated by a widely available rapid antigen diagnostic test (Ag-RDT) the results of which are available within half an hour. These Ag-RDT results are commonly verified by a nucleic acid amplification test (NAAT), whose results are only available after a further 24 h. CASE PRESENTATION: A 68-year-old male patient with the diagnosis of COVID-19 pneumonia was referred to our Intensive Care Unit (ICU) from another hospital after testing positive on an Ag-RDT. While the initial therapy was focused on COVID-19, the patient developed a fulminant septic shock within a few hours after admission to the ICU, unresponsive to maximum treatment. SARS-CoV-2 NAATs were negative, but bacteremia of C. canimorsus was diagnosed post-mortem. Further anamnestic information suggest that a small skin injury caused by a dog leash or the subsequent contact of this injury with the patient's dog could be the possible point of entry for these bacteria. CONCLUSION: During the acute phase of hyperinflammation and cytokine storm, laboratory results can resemble both, sepsis of bacterial origin or SARS-CoV-2. This means that even in the light of a global SARS-CoV-2 pandemic, where this diagnosis provides the most salient train of thoughts, differential diagnoses must be considered. Ag-RDT can contribute to early detection of a SARS-CoV-2 infection, but false-positive results may cause fixation errors with severe consequences for patient outcome.

Septic Shock Due to Capnocytophaga canimorsus Infection in a Splenectomized Patient.

Capnocytophaga canimorsus is a gram-negative rod that is part of the commensal flora of dogs' mouths. Among splenectomized patients who maintain close contact with dogs, the bacteria can lead to infection and fulminant sepsis even without evidence of a skin breach. In this report, we describe the case of a 71-year-old woman who had undergone splenectomy 35 years ago. She came to our emergency department complaining of back pain, myalgia, asthenia, and a fever of 40.2ºC. No other symptoms were noted upon her admission. Blood workup revealed hyperlacticaemia, increased C-reactive protein, and lymphopenia. A urinalysis and chest radiography were ordered, with no abnormal findings, and the SARS-CoV-2 test was negative. The patient developed persistent hypotension and drowsiness that did not improve with intravenous fluids. Therefore, she was started on a norepinephrine infusion. Cultures were collected, and intravenous antibiotic therapy was started with amoxicillin/clavulanic acid 2.2 mg and azithromycin 500 mg. Besides all the diagnostic tests, no infectious cause was found. On the second day of hospitalization, she started to deteriorate, and antibiotic therapy was escalated to piperacillin/tazobactam 4.5 g, resulting in a good clinical response. On the third day after admission, thanks to a group discussion, we were able to identify C. canimorsus in the patient's blood cultures. A review of history revealed that the patient was in close contact with her pet dog. This case highlights the importance of a multidisciplinary discussion, including the microbiology team, in order to reach an uncommon diagnosis. When dealing with splenectomized individuals presenting with the septic shock of unclear origin, a history of close contact with dogs must lead clinicians to consider C. canimorsus as a causative agent.