A case of Capnocytophaga canimorsus endocarditis in a non-immunosuppressed host: the value of 16S PCR for diagnosis

McNicol, Mark; Yew, Peter; Beattie, G. C.; Loughlin, Laura

doi:10.1099/acmi.0.000235

Cited by 6 publications

(10 citation statements)

References 4 publications

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“…Therefore, this technique remains of high interest in rare and hard-to-diagnose diseases. 16S rRNA PCR has also shown good diagnostic results on other types of samples such as cerebro-spinal fluids or cardiac valves [ 7 , 11 ]. Fast next generation sequencing strategies are being developed and will probably enable more rapid and accurate identification of bacteria [ 12 ], even though their implementation in clinical laboratories for routine diagnosis is still difficult [ 13 ].…”

Section: Discussionmentioning

confidence: 99%

Routine use of 16S rRNA PCR and subsequent sequencing from blood samples in septic shock: about two case reports of Capnocytophaga canimorsus infection in immunocompetent patients

et al. 2022

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Background Capnocytophaga canimorsus infection happens frequently in immunosuppressed patients with reported domestic animal bites. Clinical presentation ranges from simple cellulitis to fulminant septic shock with disseminated intravascular coagulopathy, with an overall mortality of 30%. Conventional blood culture is often negative as this is a slow-growing pathogen. Nevertheless, the increasing use of 16S rRNA gene amplification and Sanger sequencing allows a much more rapid diagnostic confirmation. We present two case reports where 16S rRNA gene sequencing helped to diagnose Capnocytophaga canimorsus infection. Case presentation Case 1: A 53-year-old man with a history of non-cirrhotic chronic alcohol consumption was admitted to the intensive care unit (ICU) for septic shock and disseminated intravascular coagulopathy (DIC) of unknown origin. Blood cultures remained negative and a 16S rRNA PCR was performed leading to the identification of Capnocytophaga Canimorsus on day 4. Targeted antibiotic therapy with ceftriaxone for 14 days lead to overall recovery. Afterwards, the patient recalled a dog bite 2 days before hospitalization with a punctiform necrotic wound localized on a finger, which was not obvious at admission. Case 2: A 38-year-old man arrived to the emergency department for acute alcohol intoxication and history of a dog bite 2 days before. At admission, septic shock with purpura fulminans was diagnosed and required ICU hospitalization, invasive mechanical ventilation, vasopressor support and renal replacement therapy due to the rapid clinical deterioration. In the context of septic shock with purpura fulminans, DIC and recent dog bite, the diagnosis of Capnocytophaga canimorsus septic shock was suspected, and early confirmed by 16S rRNA PCR coupled to Sanger sequencing on day 2. Blood cultures became only positive for Capnocytophaga canimorsus 5 days after admission. Ceftriaxone alone was infused for 10 days in total, and the patient was discharged from the ICU on day 25. Conclusions 16S rRNA gene PCR proves an important diagnostic tool when facing a sepsis of unknown origin. In these two cases of septic shock related to Capnocytophaga canimorsus, initial blood cultures remained negative at 24 h, whereas the diagnosis was achieved by 16S rRNA PCR sequencing performed from blood samples obtained at admission.

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Section: Discussionmentioning

confidence: 99%

Routine use of 16S rRNA PCR and subsequent sequencing from blood samples in septic shock: about two case reports of Capnocytophaga canimorsus infection in immunocompetent patients

et al. 2022

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“…As one might expect from a molecular diagnostic assay, a number of non-culturable or fastidious organisms are detected (). These organisms are very rarely (or in some cases never) identified in the clinical microbiology laboratory using culture-based methods [3–6]. Molecular diagnostic techniques are only applied to selected specimens in a limited number of laboratories, therefore the true incidence of such pathogens as the causative agents of infection may be much higher.…”

Section: Discussionmentioning

confidence: 99%

“…Molecular techniques are used in the clinical bacteriology laboratory to support culture-based methodologies; for instance, PCR-based assays are employed to detect pathogens that prove difficult (or impossible) to culture, a common scenario in patients whose infections are treated empirically with antibiotics [1, 2]. Additionally, they are useful for detecting fastidious or slow-growing bacterial pathogens [3–6]. This is in contrast to the clinical virology laboratory, where PCR and other molecular diagnostic methods have revolutionised the speed and sensitivity of testing for viral infections, replacing viral culture [7].…”

Section: Introductionmentioning

confidence: 99%

Diagnostic yield of broad-range 16s rRNA gene PCR varies by sample type and is improved by the addition of qPCR panels targeting the most common causative organisms

Harris

Brown

2022

Journal of Medical Microbiology

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Introduction. Molecular techniques are used in the clinical microbiology laboratory to support culture-based diagnosis of infection and are particularly useful for detecting difficult to culture bacteria or following empirical antimicrobial treatment. Hypothesis/Gap Statement. Broad-range 16S rRNA PCR is a valuable tool that detects a wide range of bacterial species. Diagnostic yield is low for some sample types but can be improved with the addition of qPCR panels targeting common bacterial pathogens. Aim. To evaluate the performance of a broad-range 16S rRNA gene PCR and the additional diagnostic yield of targeted qPCR applied to specimens according to a local testing algorithm. Methodology. In total, 6130 primary clinical samples were collected as part of standard clinical practice from patients with suspected infection during a 17 month period. Overall, 5497 samples were tested by broad-range 16S rRNA gene PCR and a panel of targeted real-time qPCR assays were performed on selected samples according to a local testing algorithm. An additional 633 samples were tested by real-time qPCR only. The 16S rRNA gene PCR was performed using two assays targeting different regions of the 16S rRNA gene. Laboratory developed qPCR assays for seven common bacterial pathogens were also performed. Data was extracted retrospectively from Epic Beaker Laboratory Information Management System (LIMS). Results. Broad-range 16S rRNA gene PCR improves diagnostic yield in culture-negative samples and detects a large range of bacterial species. Streptococcus spp., Staphylococcu s spp. and the Enterobacteriaceae family are detected the most frequently in samples with a single causative organism, but mixed samples frequently contained anaerobic species. The highest diagnostic yield was obtained from abscess, pus and empyema samples; 44.9 % were positive by 16S and 61 % were positive by the combined 16S and targeted qPCR testing algorithm. Samples with a particularly low diagnostic yield were blood, with 3.3 % of samples positive by 16S and CSF with 4.8 % of samples positive by 16S. The increased diagnostic yield of adding targeted qPCR is largest (~threefold) in these two sample types. Conclusion. Broad-range PCR is a powerful technique that can detect a very large range of bacterial pathogens but has limited diagnostic sensitivity. The data in this report supports a testing strategy that combines broad-range and targeted bacterial PCR assays for maximizing diagnosis of infection in culture-negative specimens. This is particularly justified for blood and CSF samples. Alternative approaches, such as metagenomic sequencing, are needed to provide the breadth of broad-range PCR and the sensitivity of targeted qPCR panels.

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“…Capnocytophaga canimorsus is a rare cause of endocarditis and it is particularly rare in immunocompetent hosts. 85 , 92 , 122 These cases of endocarditis share a common factor: the difficult process of microorganism isolation that occurred after many blood cultures or after PCR analysis of valvular tissue.…”

Section: Review Of the Literaturementioning

confidence: 99%

“…The published literature offers some descriptions of purulent cases of meningitis caused by C. canimorsus, whose identification was possible by broad-range polymerase chain reaction (PCR) of cerebrospinal fluid (CSF) or 16S ribosomal RNA amplification from blood and CSF samples 72,128,138 Capnocytophaga canimorsus is a rare cause of endocarditis and it is particularly rare in immunocompetent hosts. 85,92,122 These cases of endocarditis share a common factor: the difficult process of microorganism isolation that occurred after many blood cultures or after PCR analysis of valvular tissue.…”

Section: Review Of the Literaturementioning

confidence: 99%

The Great pretender: the first case of septic shock due to Capnocytophaga canimorsus in Sardinia. A Case report and review of the literature

Sardo

Pes

Corona

et al. 2022

Journal of Public Health Research

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Capnocytophaga canimorsus (C. canimorsus) is an emerging pathogen in critical care. C. canimorsus is a Gram-negative bacillus, commonly isolated as a commensal microorganism of the oral flora of healthy dogs and cats. A 63-year-old woman came to the emergency department with fever, chills, and malaise 2 days after a minor dog bite. After admission to the medicine ward, she developed respiratory failure and livedo reticularis. In the intensive care unit (ICU), she presented full-blown septic shock with thrombocytopenia, coagulopathy, severe acute kidney injury, and liver injury. We describe the first case of septic shock with Multiple Organ Dysfunction Syndrome related to Capnocytophaga canimorsus infection in Sardinia and its treatment in a tertiary hospital ICU. We also review recent literature on the relevance of C. canimorsus in human disease and critical illness.

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A case of Capnocytophaga canimorsus endocarditis in a non-immunosuppressed host: the value of 16S PCR for diagnosis

Cited by 6 publications

References 4 publications

Routine use of 16S rRNA PCR and subsequent sequencing from blood samples in septic shock: about two case reports of Capnocytophaga canimorsus infection in immunocompetent patients

Routine use of 16S rRNA PCR and subsequent sequencing from blood samples in septic shock: about two case reports of Capnocytophaga canimorsus infection in immunocompetent patients

Diagnostic yield of broad-range 16s rRNA gene PCR varies by sample type and is improved by the addition of qPCR panels targeting the most common causative organisms

The Great pretender: the first case of septic shock due to Capnocytophaga canimorsus in Sardinia. A Case report and review of the literature

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