Non-typeableHaemophilus influenzaeinfective endocarditis in a renal transplant recipient: compromised host or virulent strain?

Abstract

Non-typeable Haemophilus influenzae (NTHI) rarely cause endocarditis. Of the limited reports of H influenzae endocarditis, most have been due to encapsulated organisms or have had limited bacterial characterisation. We encountered a transplant recipient with native valve NTHI endocarditis and were intrigued to find no previous descriptions of this entity. Although it was tempting to ascribe this infection to our patient's immunocompromised status, we investigated his pathogen further and found that it displayed features common to invasive NTHI strains including gene expression for two IgA proteases and serum resistance. Multilocus sequence typing grouped our NTHI strain with MLST 159, a group associated with invasive NTHI infections. Our strain shared identical outer membrane protein P2 sequences and protein patterns with MLST 159 strains. Aside from providing the first characterisation of native valve NTHI infection, our investigation reveals features of epidemiologically unrelated, clonal NTHI strains that have a predilection for invasive infections.

Infective endocarditis in the setting of renal transplantation: Case report and review of the literature

“…In 10 (14%) of the cases, the pathogen was isolated from a vegetation specimen taken either during heart surgery or autopsy. The stratification of the isolated pathogens is shown in Table …”

“…Endocarditis involved the left side of the heart in 66 cases (89%) and the right side in 6 (8%); two cases were defined as mural IE. The stratification of involved heart structures is shown in Table . Only five patients (7%) had a known preexisting valvular disease: rheumatic heart disease in two, a prosthetic valve in two, and aortic stenosis in one.…”

Whole genome sequencing identifies opportunistic non-typeable Haemophilus influenzae rather than a hypervirulent clone

“…10 Two Ig A proteases (igaA, igaB genes) are implicated in chronic obstructive pulmonary disease associated pneumonia; serum resistance in infective endocarditis and adhesin proteins are described. 5,11 Sequencing detected the presence of hmw C and pepN adhesins in our isolates. Adhesins mediate the attachment to human epithelial cells and promote colonisation.…”

“…3,4 The growing cohort of immunocompromised patients from malignancy, its treatment and organ transplantation create a susceptible population. 5 In the absence of an opsonising and phagocytosis evading polysaccharide capsule, IgA proteases, serum resistance and adhesins are the main virulence characteristics for NTHI. 1 We unexpectedly observed four cases of invasive NTHI over 7 months and investigated whether there was an unusually virulent clone circulating in our immunocompromised patient population.…”

Infective endocarditis caused by non‐typeable Haemophilus influenzae

“…Previously, two cases of IE caused by NTHi were reported . One case was an immune‐compromised individual who experienced kidney transplantation and who was receiving immunosuppressive drug therapy.…”