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Diagnostic Approach to Rash and Fever in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Lee S. Engel, Charles V. Sanders, Fred A. Lopez
Capnocytophaga canimorsus is a fastidious gram-negative bacillus that is part of the normal gingival flora of dogs and cats [72,73]. Human infections are associated with dog or cat bites, cat scratches, and contact with wild animals [72,73]. Predisposing factors include trauma, alcohol abuse, steroid therapy, chronic lung disease, and asplenia [72,73]. The clinical syndrome consists of fever, disseminated intravascular coagulation (DIC), necrosis of the kidneys and adrenal glands, thrombocytopenia, hypotension, and renal failure. The mortality rate approaches 25%.
Bites and stings
Published in Biju Vasudevan, Rajesh Verma, Dermatological Emergencies, 2019
Common pathogens associated with bite wounds include streptococci, staphylococci, Pasteurella spp., Capnocytophaga canimorsus, and anaerobes. Breast implant infection and lung abscesses due to Pasteurella multocida have both been linked to cats, and staphylococcal endocarditis has been reported after a cat bite. Brain abscess formation has been observed following a dog bite. In immunocompromised patients, there is a significant risk of Pasteurella or Capnocytophaga sepsis. Capnocytophaga canimorsus sepsis has a high mortality rate and has been associated with purpura fulminans. Human bites have a higher likelihood of infections with Staphylococcus aureus and Eikenella corrodens.
Hands
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
Capnocytophaga canimorsus may cause severe sepsis after contact with dog saliva, especially in post-splenectomy patients (Bulter T, Eur J Clin Microbiol Infect Dis, 2015). Penicillin is the drug of choice.
Capnocytophaga canimorsus – a potent pathogen in immunocompetent humans – systematic review and retrospective observational study of case reports
Published in Infectious Diseases, 2020
Naomi Mader, Fabian Lührs, Martin Langenbeck, Stefan Herget-Rosenthal
Capnocytophaga canimorsus (C. canimorsus) is a Gram-negative rod and facultative anaerobic bacterium that inhabits the oral cavity of some mammals. It was first described in 1976 and 1977 [1,2]. C. canimorsus infection is most frequently transmitted by dog bites and cat scratches. C. canimorsus is highly virulent and able to resist the innate immune system due to characteristics of catalase and cytotoxin production enabling to survive phagocytosis, crossing tissue into the bloodstream by its gliding motility, and resistance to killing by serum complement [3–5]. Furthermore, C. canimorsus elicits only limited inflammatory response as there is no interaction of its lipopolysaccharide with toll-like receptor 4, the usual lipopolysaccharide receptor [5].
The challenge of diagnostic metagenomics
Published in Expert Review of Molecular Diagnostics, 2018
The case reports themselves deserve some brief review, though this has been performed elsewhere [1]. As with many cases, appropriate clinical care can mask the diagnostic difficulty. The hallmark 2014 patient from the NEJM manuscript of actionable metagenomics was notably treated in a manner very different than proposed in Infectious Disease Society of America encephalitis guidelines [37]. The immunocompromised patient never received a third-generation cephalosporin or ampicillin, which would have likely treated the underlying leptospirosis infection, rendering the metagenomics unnecessary [38]. The lone case report from Karius published at the time of writing also illustrates a curious treatment approach of levofloxacin in the setting of dog bites and acute respiratory distress as well as the importance of referral to tertiary care [39]. The resultant metagenomic diagnosis of Capnocytophaga canimorsus on a plasma specimen positive for Gram-negative rods beats the blood culture positive result by several hours and had no effect on treatment as the clinicians had already covered for infections associated with sepsis and dog bites. Perhaps a major takeaway from the story is how Food and Drug Administration (FDA) sanctioning of databases (in this case, a manufacturer’s matrix-assisted laser desorption/ionization-time of flight [MALDI-TOF] database) affects the utility of less biased techniques [40]. A similar lack of actionability is seen in several of the other cases that have been reported to date [1,41–45]. Of course, there are notable exceptions, including a case of neurobrucellosis that was provisionally diagnosed as tuberculous meningitis, resulting in treatment that otherwise would not have been given empirically in a pediatric setting [46]. And there are always gaps in the practice of clinical medicine that laboratory assays will need to catch, not least the errors of other laboratory tests. Not every patient is treated according to guidelines nor reads the textbook. But to date, the argument for the technique has been largely based on such cases and the denominator of sequencing required to find such cases has not routinely been reported. Recent cost-effectiveness modeling of metagenomics in the diagnosis of fever of unknown origin concluded that, even after limiting the cost of diagnostic metagenomics to $100–1000 per test, it would require 2.5–4 times the diagnostic yield of computed tomography of the abdomen/pelvis in order to be cost neutral and cautioned against a ‘widespread rush’ to deploy metagenomic testing [47].