Haemophilus influenzae PittGG

Haemophilus influenzae is a non-motile, Gram-negative bacterium that is an obligate resident of the human respiratory mucosa. Numerous studies have suggested that H. influenzae, present in the nasopharynx of the majority of children and adults, is a common cause of superinfection following upper respiratory viral infections. The presence of a polysaccharide capsule by some strains has provided for the division of the species into typeable (serotypes a-f) and nontypeable (NTHi) isolates. The majority of clinical isolates are NTHi, and they are associated with a spectrum of acute and chronic respiratory mucosal infections as well as a range of systemic disease states, suggesting a wide range of virulence phenotypes. Genomic studies have demonstrated that each clinical strain contains a unique genic distribution from a population-based supragenome, the distributed genome hypothesis. The distributed genome hypothesis posits that chronic bacterial pathogens utilize polyclonal infection and reassortment of genic characters to ensure persistence in the face of adaptive host defenses. Studies based on random sequencing of multiple strain libraries suggested that free-living bacterial species possess a supragenome that is much larger than the genome of any single bacterium; a typical pair of genomes varies by nearly 400 genes. Both PittEE and PitEE were derived from pediatric middle-ear specimens, with PittGG, a consistently virulent strain in animal models isolated from a child with a perforated tympanic membrane, whereas PittEE was obtained from a child undergoing tympanostomy and tube placement for chronic otitis media with effusion, a less virulent disease (adapted from PubMedID 17570853 and 17550610). (EBI Integr8)