Virulent endocarditis due to Haemophilus parainfluenzae: A systematic review of the literature

Abstract

BACKGROUND Haemophilus parainfluenzae (HPI) belongs to the HACEK ( Haemophilus spp., Aggregatibacter spp., Cardiobacterium spp., Eikenella spp., and Kingella spp.) group of organisms. The HACEK group of organisms are a part of the oropharyngeal flora and can cause invasive opportunistic infection such infective endocarditis (IE) in hosts with compromised immunological barriers. AIM To perform a 20-year systematic review of the literature characterizing the clinical presentation, epidemiology and prognosis of HPI IE. METHODS We performed a systematic review of Medline, Pubmed, Scopus and Embase from 2000 to 2022 to identify all cases of HPI IE. RESULTS Thirty-nine adult cases were identified. HPI IE was found to affect males slightly more than females and is common in patients with predisposing risk factors such as underlying valvular abnormalities. It mostly affected the mitral valve and had an indolent course; significantly sized vegetations (> 1 cm) developed in most cases. Central nervous system septic embolization was common. It had a favorable prognosis compared to staphylococcal and streptococcal IE. CONCLUSION Clinicians should be attentive to the indolent course of HPI IE and the presence of predisposing risk factors in order to allow for timely management.

Haemophilus parainfluenzaeinfective endocarditis complicated by multiorgan septic emboli

“…With regard to demographics, early case reports and reviews reported a slight proclivity for H. parainfluenzae endocarditis in women, however, subsequent case series have shown a reversal with men accounting for a slight majority of cases 7–9. Similar to our patient, most cases reported in the literature occur in a younger population, typically one with fewer comorbidities compared with other causes of endocarditis.…”

“…The clinical course of IE with this group of organisms has been described as subtle, with an average delay in diagnosis of 1–3 months depending on the species 11. This delay has shortened over time, likely due to improved growth and identification on current media, leading to earlier identification of the implicated pathogen 7. However, diagnosis is still relatively delayed compared with other more common pathogens causing endocarditis.…”

“…Typical presentations vary, however, most patients reported in the literature did present with fevers, many often with a non-specific constellation of symptoms (fatigue, weight loss and dry cough) that can make diagnosis challenging initially 7. Patients are often misdiagnosed with a respiratory illness prior to diagnosis of endocarditis, in large part due to the non-specific symptoms often reported on presentation.…”

“…Similar to our patient, most cases reported in the literature occur in a younger population, typically one with fewer comorbidities compared with other causes of endocarditis. The majority of reported cases involved the mitral valve, however, more recently, there has been an increase in reported cases with involvement of tricuspid and pulmonic valves, likely reflective of the increasing association with IDU 7. Despite the increase in IDU as a risk factor, dental disease and respiratory infection remain known risk factors for the development of HACEK endocarditis.…”

“…Overall, 80%–90% of all cases of IE are caused by gram-positive bacteria, more specifically streptococci, staphylococci and enterococci 1 2. HACEK organisms ( Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella corrodens and Kingella species) are fastidious, gram-negative bacteria that frequently colonise the oropharynx of humans that can also cause IE 3–9. These organisms have been reported to be responsible for 1.5%–3% of all cases of IE, however, rates as high as 5%–10% have been reported in some case series 3–5 10.…”