Interaction of capsulate Haemophilus influenzae with human airway mucosa in vitro

Abstract

Two pairs of isogenic capsulate and noncapsulate and one pair of capsulate fimbriate and nonfimbriate strains of Haemophilus influenzae type b were studied in an organ culture of human respiratory mucosa. Over 24 h, the numbers of recovered bacteria increased from the original inoculum size of 10i to 108 CFU/ml. Transmission electron microscopy and scanning electron microscopy showed that noncapsulate organisms caused significant epithelial damage, whereas capsulate strains did not. Association of noncapsulate bacteria with damaged epithelial cells was observed by 14 h of incubation. In contrast, capsulate organisms were associated with a dense, thick, gel-like matrix which was observed above the epithelial surface. These capsulate organisms were not seen to associate with the epithelial surface (by transmission electron microscopy), though they were occasionally seen adhering to cells by scanning electron microscopy. Fimbriate capsulate H. influenzae showed increased adherence to buccal cells compared with nonfimbriate capsulate organisms. There was also association of fimbriate capsulate bacteria with damaged organ culture epithelium in one of four experiments. It is concluded that both capsule and fimbriae affect the interaction of H. influenzae with human airway mucosa in vitro by influencing adherence to and damage of the epithelium.

Molecular determinants of the pathogenesis of disease due to non-typableHaemophilus influenzae

“…Studies with adenoids and nasal turbinate tissue in organ culture indicate that piliated organisms tend to adhere to areas of damaged epithelium [101–103]. To underscore the potential role of pili in H. influenzae colonization, Weber et al demonstrated that, in yearling monkeys, the density of colonization was greater for piliated H. influenzae type b than for isogenic non‐piliated organisms with an insertionally inactivated hifA gene [104].…”

The Fimbria Gene Cluster of Nonencapsulated Haemophilus influenzae

“…Haemophilus influenzae infections, including otitis media, sinusitis, pneumonia, and persistent infections in chronic bronchitis patients, are preceded by airway colonization, which is a process facilitated by fimbria (8,24,32,39,54). Four families of fimbriae have been distinguished morphologically (5).…”

A novel in silico approach to identify potential therapeutic targets in human bacterial pathogens

“…This protein is supposed to have role in the modulation of fimbria expression genes, PUR and ILE, and inhibit their translation. The airway colonization of H. influenzae in host is facilitated by fimbria (Read et al 1992;Van Alphen and van Ham 1994). This hypothetical protein may even serve as mammalian tumor-associated antigen.…”