Recurrent invasive Haemophilus influenzae serotype a infection in an infant

Abstract

Background: Before introduction of conjugated Haemophilus influenzae serotype b (Hib) vaccines into the routine childhood immunization programs, Hib was a major cause of meningitis in infants and children under the age of 5. In the post-Hib vaccine era, the epidemiology of invasive H. influenzae has changed substantially with most invasive diseases now caused by non-Hib strains, including H. influenzae serotype a (Hia) and serotype f, as well as non-encapsulated or non-typeable strains. This case report describes the microbiology of Hia in a recurrent invasive infection in an infant. The Hia strain involved is described together with current knowledge of Hia infection including methods of protection. Methods: Isolates were characterised by Gram stain, growth factor requirements, biotype, serotype, detection of IS1016-bexA deletion, multilocus sequence typing, pulsed-field gel electrophoresis and antimicrobial susceptibility testing. Results: All three isolates appeared to be identical, belonged to biotype II, serotype a, sequence type 23, lacked the IS1016-bexA partial deletion, and were susceptible to commonly prescribed antibiotics tested. Conclusion: Hia has emerged as a significant invasive pathogen in the post Hib vaccine era. MLST and PFGE serve as useful techniques for typing of Hia. Many attributes of Hia and the disease it causes bear resemblance to Hib and Hib disease, including the ability to cause recurrent infections. This raises the potential for protection by vaccination and chemoprophylaxis.

Epidemiology of invasive pneumococcal and Haemophilus influenzae diseases in Northwestern Ontario, Canada, 2010–2015

“…Collaboration between the Public Health Agency of Canada, the National Research Council, and the Northern Ontario School of Medicine was initiated in 2013 with the aim of improving Hia surveillance and developing a Hia vaccine programme (Boisvert and Moore, 2015). Vaccination and chemoprophylaxis, prevention strategies proven effective against Hib, are possible means of protecting against Hia (Whyte et al, 2015). Other potential interventions affecting the social determinants of health could reduce carriage of H. influenzae and S. pneumoniae and the incidence of invasive pneumococcal and non-b and NTHi diseases.…”

“…It can cause septicaemia and meningitis, mainly in children <2 years of age. H. influenzae type a (Hia) is the second most virulent serotype (Whyte et al, 2015). NTHi most commonly cause respiratory tract infections (Musher, 1996).…”

Invasive Disease due to Haemophilus influenzae Type A in Children in Canada’S North: A Priority for Prevention

“…Outbreaks occurred in Alaska in 2003 and 2009 to 2011 ( 3 , 8 ), as well as in Nunavik, northern Quebec, from 2012 to 2013 ( 10 ). Recurrent disease has been reported in three apparently healthy children who were <10 months of age at initial infection ( 11 , 12 ). Case fatality rates of 5.5% to 16% have been observed ( 6 , 8 , 9 ).…”

Laboratory characterization of invasiveHaemophilus influenzaeisolates from Nunavut, Canada, 2000–2012

“…Given the severity of illness due to Hia ( 34 , 35 ), sporadic and recurrent Hia infections as well as potential Hia outbreaks ( 31 , 36 , 37 ) pose a significant threat. In addition, the lack of a vaccine and the lack of published guidelines for the prophylaxis of contact exposure may represent a gap in our public health system for an emerging pathogen in a vulnerable population.…”