Rare but Not Infrequent: Infective Endocarditis Caused byAbiotrophia defectiva

Abstract

Endocarditis (IE) is defined by an infection of a native or prosthetic heart valve, the mural endocardium, or an indwelling cardiac device. Although viridan-group streptococci (VGS) and Staphylococci species have collectively been considered as the most common cause of endocarditis, uncommon pathogens may also lead to the disease with significant morbidity and mortality. Abiotrophia defectiva, a nutritionally variant streptococci (NVS), is a virulent bacterium that preferentially affects endovascular structure and is implicated in many culture-negative endocarditis with dreadful complications such as heart failure, septic embolization, and valve destruction. Here, we report a case of a 60-year-old male patient, with a past medical history significant for hypertrophic obstructive cardiomyopathy, who was incidentally found to have mitral valve vegetative mass with an uncommon agent, A. defectiva. The patient was successfully treated with antimicrobial therapy. The objective of this article is to describe the possibility of uncommon cause of common diseases and raises awareness of infective endocarditis caused by A. defectiva among clinicians and microbiologists. Early and proper identification of this pathogen is important to achieve a better outcome.

Seven Year Old Male with Tricuspid Endocarditis

“…Given the clinical history, presentation, physical exam and bedside ultrasound findings, the diagnosis of a TV endocarditis in the context of an undiagnosed basal VSD was entertained in the context of a preceding viral prodrome and poor dentition. This diagnosis was confirmed on formal echocardiography and blood cultures were positive for abiotrophia defectivia [2]. This bacteria is a variant of the viridans species of streptococcus, commonly known as the causative bug for endocarditis [2].…”

“…This diagnosis was confirmed on formal echocardiography and blood cultures were positive for abiotrophia defectivia [2]. This bacteria is a variant of the viridans species of streptococcus, commonly known as the causative bug for endocarditis [2]. It is quite virulent and has a predisposition for affecting endovascular structures including heart valves [2].…”

The Versatility of Opportunistic Infections Caused by Gemella Isolates Is Supported by the Carriage of Virulence Factors From Multiple Origins

“…Gemella and Streptococcus show ecological -even with physical contact inside biofilms (Mira, 2008) -and genetic proximity, which would facilitate DNA exchange and its conservation given that the selective forces are similar. Notably, such gene transfer appears to involve also other commensal oral genera from different taxonomic families with a comparable virulence pattern to Gemella, such as Abiotrophia, Granulicatella, and Parvimonas (Ohara-Nemoto et al, 2005;Baghban and Gupta, 2016;Chowdhury and German, 2018). Altogether, data suggest the existence of a gene pool in the oral bacterial environment permitting these species to increase their abilities to survive and cause invasive diseases such as endocarditis, sepsis, abscesses and/or joint infections.…”

Abiotrophia defectiva: A Rare but Critical Cause of Infective Endocarditis

“…Infective endocarditis (IE) is defined as an infection of a native or prosthetic heart valve, the mural endocardium, or an indwelling cardiac device. Although viridans group Streptococci (VGS) and Staphylococci species are considered as the most common cause of endocarditis, uncommon pathogens may also lead to the disease with significant morbidity and mortality [1]. Though rare, nutritionally variant Streptococci (NVS) are estimated to cause approximately 5%-6% of all cases of IE, including being a major cause of blood culture-negative IE [2].…”

“…Though rare, nutritionally variant Streptococci (NVS) are estimated to cause approximately 5%-6% of all cases of IE, including being a major cause of blood culture-negative IE [2]. If not treated early, fatal complications such as heart failure, septic embolization, and valve destruction can occur [1]. Here we present a case of a 44-year-old female who presented with fever and easy fatiguability since two weeks and was eventually diagnosed with IE due to Abiotrophia defectiva.…”