Haemophilus influenzae Infections in the H. influenzae Type b Conjugate Vaccine Era

Abstract

The widespread use of Haemophilus influenzae type b (Hib) conjugate vaccines has nearly eradicated invasive Hib disease where the vaccines are used. This success was accompanied by a shift in capsular serotypes of invasive H. influenzae disease, with nontypeable strains replacing type b strains as the most common bloodstream isolate, but there is no convincing evidence of a true increase in the incidence of non-serotype b invasive infections. H. influenzae causes predominantly mucosal infections. The introduction of vaccines for otitis media and global shifts in antimicrobial susceptibility emphasize the importance of continued surveillance of H. influenzae colonization and disease patterns.

Adhesin genes and serum resistance in Haemophilus influenzae type f isolates

“…In the post-Hib vaccine era, invasive disease in children due to H. influenzae is uncommon, with the majority of these infections due to unencapsulated strains, with the remainder being non-b encapsulated strains, predominantly serotypes f and a in North America and serotypes f and e in Europe (Tsang et al, 2006;Adam et al, 2010;Ladhani et al, 2010Ladhani et al, , 2012Agrawal & Murphy, 2011;Resman et al, 2011a;Rubach et al, 2011). To understand better the ability of serotype f strains to produce invasive infection, we assembled a panel of Hif isolates from a diversity of clinical sources for factors related to pathogenesis.…”

“…meningitis, epiglottitis, septicaemia and osteomyelitis) in previously well infants and children (Aubrey & Tang, 2003). Since the early 1990s, routine administration of the Hib conjugate vaccines (which induce protective levels of anti-capsular antibody) has virtually eliminated Hib disease among infants and young children in developed countries (Agrawal & Murphy, 2011;Ladhani, 2012). However, the vaccine provides no protection from infection due to nonb serotypes, including H. influenzae serotype f (Hif), which remains a rare but significant cause of invasive infection.…”

Invasive Haemophilus influenzae Infection in Patients with Cancer

“…[5][6][7][8][9] NTHi is also considered to be a significant cause of invasive H influenzae infection. [5][6][7][8][9][10][11][12] Several risk factors exist for invasive H influenzae infections, including malignant neoplasms, asplenia, agammaglobulinemia, alcohol use disorder, AIDS, chronic pulmonary diseases, long-term steroid use, and undergoing chemotherapy, radiotherapy, or stem cell transplantation. [2][3][4]6,11,13,14 Because malignancy is a risk factor for such infection, we report on our experience with H influenzae bacteremia since 2000 in our patients with cancer, including both solid and hematological malignancies, and their association with other comorbidities.…”

Haemophilus influenzae surface fibril (Hsf) is a unique twisted hairpin-like trimeric autotransporter

“…H. influenzae type b (Hib) causes pneumonia, osteomyelitis, epiglottitis, sepsis, joint infections, and acute meningitis and is hence considered as the most virulent type (Morris et al, 2008;Agrawal and Murphy, 2011). Even though the incidence of Hib infections in developed countries has been significantly reduced after introduction of the Hib conjugate vaccine in the early 1990s (Danovaro-Holliday et al, 2008), Hib remains a major infectious agent in infants and children in developing countries (Fitzwater et al, 2010).…”

“…Even though the incidence of Hib infections in developed countries has been significantly reduced after introduction of the Hib conjugate vaccine in the early 1990s (Danovaro-Holliday et al, 2008), Hib remains a major infectious agent in infants and children in developing countries (Fitzwater et al, 2010). Hib infection starts by attachment of the bacteria to the nasopharyngeal and lung epithelial surfaces resulting in epithelial damage followed by penetration of the underlying tissues mediated by various sophisticated mechanisms (Geme and Cutter, 1995;Geme, 1996;Ulanova and Tsang, 2009;Agrawal and Murphy, 2011). Hib is furthermore able to penetrate the blood-brain barrier and thus causes meningitis (Singh et al, 2012).…”