DefinePK

Abstract

Hemophilus influenzae is a Gram-negative bacterium exhibiting the characteristics of a facultative anaerobe. The bacterium requires capnophilic conditions for its growth. These bacteria are classified as fastidious organisms because they require X and V factors for their growth. They are present as commensals on the mucosa of the upper respiratory tract of humans. Haemophilus influenzae has no veterinary importance; it is exclusively adapted to its human host. The nontypeable strain (non-encapsulated) is mostly present in the normal flora of humans, but the typeable strain (encapsulated) can also exist as a commensal. To make a precise determination about infectious agents, methods of molecular characterization help distinguish among closely related isolates. Molecular characterization of Haemophilus influenzae is based on biochemical characteristics, capsular types, biotypes, lipopolysaccharide, and lipooligosaccharide, providing valuable insights into pathogenicity, resistance mechanisms, and epidemiology of this exclusive human pathogen. Laboratory diagnosis is done for the precise understanding of vaccine efficacy, disease outbreak monitoring, clinical management, and surveillance purposes. Protein-conjugated vaccine is used for its prevention. This has significantly reduced the incidence of Hib diseases. Still, simultaneously, the emergence of NTHi infections has also been reported, keeping in mind that NTHi is a prominent cause of otitis media, sinusitis, chronic obstructive pulmonary disease (COPD), and other invasive conditions in susceptible populations. However, utilizing surface proteins as a vaccine antigen can pave the way towards protective immunization against the NTHi strains. Additionally, the interdisciplinary relationship of molecular analysis with other areas of genomic research in determining pathogenicity, antibiotic resistance, vaccine efficacy, of pre- and post-vaccinal disease epidemiology is the main subject of this review; therefore, an effective approach towards molecular characterization can pave the way for developing protein-based vaccines for the control of NTHi infections in the post-Hib vaccine era.