Haemophilus influenzae (H. influenzae)

Haemophilus influenzae is a Gram-negative, pleomorphic, coccobacillary bacterium that is a significant human pathogen, particularly in children and the immunocompromised [1][2]. It is classified into six capsular serotypes (a-f) and non-encapsulated (non-typeable) strains; of these, serotype b (Hib) was historically the most common cause of invasive disease, including bacterial meningitis and epiglottitis, before the widespread use of conjugate vaccines [3][4]. The organism is fastidious, requiring hemin (X factor) and nicotinamide adenine dinucleotide (V factor) for growth in laboratory settings, typically on chocolate agar [2]. It colonizes the human nasopharynx and can spread locally to cause otitis media or sinusitis, or disseminate through the bloodstream to cause systemic infections [1]. In a pharmacological context, the bacterium contains various molecular targets such as penicillin-binding proteins and ribosomes, which are the focus of antibiotic therapy [5]. Although it is a biological entity rather than a single molecular receptor, it remains a primary target for antimicrobial development and public health immunization strategies [3][4].

Other names

Hemophilus influenzaPfeiffer's bacillusH. influenzae

Drugs targeting this organism typically inhibit bacterial cell wall synthesis (Beta-lactams like Ceftriaxone), inhibit protein synthesis (Macrolides like Azithromycin), or inhibit DNA gyrase/topoisomerase IV (Fluoroquinolones like Ciprofloxacin) [1][2]. Vaccines induce the production of antibodies against the polyribosylribitol phosphate (PRP) capsular polysaccharide [3].