Nontoxinogenic corynebacterium diphtheriae as a rare cause of native endocarditis in childhood

Retrospective Study of Infections with Corynebacterium diphtheriae Species Complex, French Guiana, 2016-2021

Human infections with Corynebacterium diphtheriae species complex (CdSC) bacteria were rare in French Guiana until 2016, when the number of cases diagnosed increased. We conducted an epidemiologic, multicenter, retrospective study of all human CdSC infections diagnosed in French Guiana during January 1, 2016-December 31, 2021. A total of 64 infectious episodes were observed in 60 patients; 61 infections were caused by C. diphtheriae and 3 by C. ulcerans. Estimated incidence increased from 0.7 cases/100,000 population in 2016 to 7.7 cases/100,000 population in 2021. The mean patient age was 30.4 (+23.7) years, and male-to-female ratio was 1.7:1 (38/22). Of the 61 C. diphtheriae isolates, 5 tested positive for the diphtheria toxin gene, and all results were negative by Elek test; 95% (61/64) of cases were cutaneous, including the C. ulcerans cases. The increase in reported human infections underscores the need to raise awareness among frontline healthcare practitioners to improve prevention.

Corynebacterium diphtheriae-infective endocarditis in a patient with an atrial septal defect closure device

An 18-year-old woman presented to our institution with fever, bilateral flank pain, headache and photophobia. She had a previous atrial septal defect (ASD) closure device inserted at the age of 9 years. Blood cultures on admission were positive for Corynebacterium diphtheriae, and transoesophageal echocardiogram (TOE) revealed an echodensity associated with the ASD closure device, most consistent with a vegetation. She was treated for infective endocarditis with 6 weeks of intravenous benzylpenicillin, and follow-up TOE showed resolution of the echodensity. To our knowledge, no cases of C. diphtheriaeendocarditis of an ASD closure device have previously been reported.

Infective endocarditis in New Zealand children 1994-2012

BACKGROUND

New Zealand is a developed country with high incidence of bacterial infections and postinfectious sequelae including rheumatic heart disease. We sought to describe the clinical and microbiology features of children with infective endocarditis (IE) between 1994 and 2012.

METHODS

Retrospective review of patients <16 years identified from hospital records.

RESULTS

In total 85 episodes occurred in 82 children and 68 (80%) were classified as Definite IE and 17 as Possible IE according to modified Duke criteria. From Pacific Island countries, 13 cases were referred. There were 72 children who originated in New Zealand, of whom 52% were either indigenous New Zealand Maori or Pacific migrants. The median age at diagnosis was 7 (0-15) years. Of the 85 cases, 51 (60%) had congenital heart disease 10 children with rheumatic heart disease developed IE. Of the 85 cases, 35 (41%) met our criteria for healthcare-associated IE. 39/85 underwent surgery for IE. As direct result of IE, 4 (4.7%) children died and 9% of survivors had neurologic sequelae. Attributable in-hospital mortality was 4.7%. Staphylococcus aureus was the most common organism, accounting for 26 episodes (30.6%). Other notable pathogens included Corynebacterium diphtheriae (10 cases, 11.8%) and Streptococcus pyogenes (7 cases, 8.2%). In 6 episodes, the microbiologic diagnosis was made by 16S ribosomal RNA testing of excised cardiac tissue.

CONCLUSIONS

Congenital heart disease was the major risk factor for IE; however, rheumatic heart disease is also an important risk factor in New Zealand, with implications for local endocarditis prophylaxis recommendations. In addition to a high burden of healthcare-associated and staphylococcal IE, pathogens such as C. diphtheriae and S. pyogenes occurred. 16S ribosomal RNA testing is a useful tool to determine the etiologic agent in culture-negative IE.

Corynebacterium propinquum as the first cause of infective endocarditis in childhood

We here present a 7-year-old girl with ventricular septum defect and ventriculoatrial communication, who developed infective endocarditis (IE) due to Corynebacterium propinquum in the tricuspid valve. The patient was admitted because of an 8-day history of fever. Transthoracic echocardiogram showed non-pedunculated vegetation on the septal leaflet of the tricuspid valve. Gram-positive coryneform bacteria grew from three consecutive sets of blood cultures taken on admission. C. propinquum was confirmed by 3 microbiological approaches; (i) biochemical testing using API Coryne panels, (ii) a sequence-based method using the 16S rRNA gene and partial rpoB sequencing, and (iii) matrix-assisted laser desorption ionization-time of flight mass spectrometry. The isolates were susceptible to a wide variety of β-lactams and vancomycin. The patient was successfully treated with antimicrobial agents without surgical intervention. There have only been available of clinical details of two adult cases of invasive C. propinquum infections; one of which was presented as IE, and the other was pleuritis in a patient with lung cancer. To the best of our knowledge, this is the first report to describe C. propinquum as a cause of IE as well as that of invasive infections in a pediatric population. Multiple methods that reliably differentiated related species helped us to establish this rare organism. Our report expanded the clinical spectrum of C. propinquum infections.