Abstract
The most common causes of infective endocarditis (IE) are Staphylococcus, Streptococcus, Enterococcus, and HACEK-related organisms. In 15–30% of the IE cases, standard blood cultures remain sterile. We aimed at identifying the causative agent of a blood-culture-negative IE by whole metagenome shotgun sequencing (WMGS). A 54-year old woman diagnosed with community-onset pneumonia by a general practitioner, was admitted with dyspnea, cough and fever. The patient's blood cultures were repeatedly negative. The transesophageal echocardiography and transthoracic echocardiography showed an echo density on the left coronary leaflet of the aortic valve and signs suggestive of a ruptured abscess of the mitro-aortic junction. The patient underwent a semi-urgent aortic valve replacement by a mechanical prosthetic valve. We extracted DNA from the surgically-removed fresh valve tissue. The extraction procedure included bacterial/fungal DNA enrichment procedure. Nextera XT library prepared from the valve DNA extract was sequenced (2 × 250) on an Illumina MiSeq instrument. Sequence reads were mapped against bacterial genomic sequences, 16S rRNA genes and clade-specific taxonomic markers. Most of the 103,136 sequencing reads classified as bacterial were assigned to Neisseria meningitidis. In line with these data, mapping of reads against clade-specific and 16S rRNA gene markers revealed N. meningitidis as the most represented species. Assembled metagenomic fragments had the best average nucleotide identity (ANI) with N. meningitidis. Comparison of assembled contigs to reference alleles showed that this strain belongs to the ST-41/44 complex. N. meningitidis is commonly associated with meningitis and/or septicemia but should not be neglected as a causative agent of IE, which became exceedingly rare with the introduction of antibiotics. Our data show that WMGS may be used as a diagnostic procedure to strengthen the diagnosis of IE and to obtain draft genomic sequence of the pathogen and typing information.
Highlights
Infective endocarditis (IE) remains a deadly disease despite significant progress in the diagnostic procedures and therapies
N. meningitidis can cause a broad spectrum of clinical manifestations and is largely known for worldwide diseases, such as purulent meningitis and/or septicemia associated with high morbidity and mortality
IE caused by N. meningitidis was more common before the antibiotic era with a trend of affecting the left side of the heart
Summary
Infective endocarditis (IE) remains a deadly disease despite significant progress in the diagnostic procedures and therapies. Because of the worsening of symptoms with the development of fever, the patient visited a general practitioner who diagnosed community-onset pneumonia and prescribed co-amoxicillin The morning, she presented at the emergency department of our hospital because of increased dyspnea. Physical examination revealed sinus tachycardia at 110/min, central temperature of 39.2◦C and a normal blood pressure of 113/69 mmHg. Cardiac examination showed a systolic murmur maximal at the aortic area and chest auscultation was compatible with left congestive heart failure. In the meantime (day 4), the patient received in addition to ceftriaxone and gentamycin, doxycycline for empirical coverage of Coxiella burnetti, Brucella spp., and Bartonella henselae The serologies for those pathogens revealed negative at day 13. The antibiotic regimen was changed (day 13) for ceftriaxone alone for a total duration of 6 weeks
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
