QseC controls biofilm formation of non-typeable Haemophilus influenzae in addition to an AI-2-dependent mechanism

Abstract

Non-typeable Haemophilus influenzae (NTHi) is a common pathogen associated with diseases such as acute otitis media or exacerbations in patients with chronic obstructive pulmonary disease. The biofilm-forming capability substantially contributes to the persistence of NTHi. However, the regulation of biofilm formation is not completely understood. Quorum sensing regulated by autoinducer-2 produced by luxS is until now the only described regulatory mechanism. In this study, we show that the two-component signalling system QseB/C is involved in the biofilm formation of NTHi in vitro. An isogenic NTHi mutant of qseC (Hi3655KR2) showed a significant decrease in biofilm formation under static and semi-static conditions as assessed by crystal violet staining. In addition, under constant flow conditions, Hi3655KR2 formed less biofilm after 48 h. The biofilm defects were irrespective of autoinducer-2 levels. Hence, here we suggest for the first time a regulatory circuit in NTHi, which controls biofilm formation by mechanisms other than or in addition to luxS-dependent factors.

Haemophilus influenzae stores and distributes hemin by using Protein E

“…laumondii TT01 was kindly provided by Dr. Nick Waterfield (University of Warwick, Coventry, UK) and stably inserted into the genome of NTHi 3655 following a strategy described previously ( Fig. S1A) (Unal et al, 2012). The promoter of protein P5 was amplified by PCR using the primers promP5_F and promP5_R (Table S1) and cloned into pKR7.1 (Su et al, 2013) that yielded the plasmid pKR7.3 after digestion by restriction enzymes EcoRV and SalI.…”

Cephalosporin-3′-Diazeniumdiolate NO Donor Prodrug PYRRO-C3D Enhances Azithromycin Susceptibility of Nontypeable Haemophilus influenzae Biofilms

“…As well as clinical isolates from a range of diseases having the ability to form in vitro biofilms (8), NTHi has also been shown to form biofilms on cultured respiratory epithelial surfaces with decreased antibiotic susceptibility (13,14). NTHi biofilms also exhibit quorum signaling that is characteristic of other respiratory biofilm formers such as P. aeruginosa (15). While P. aeruginosa is the most widely studied biofilm-forming respiratory pathogen, many differences exist with NTHi.…”

Identification of a Haemophilus influenzae Factor H–Binding Lipoprotein Involved in Serum Resistance

“…A control strain Hib 21.3 also was created by insertion in the same locus of nptI. A vector containing the intergenic HIB_08720 was constructed as previously described to yield pKR21 (30). The multiple cloning sites and the nptI gene were amplified by PCR using pKR7.3 as a template with primers PP5_ilvA_F and PP5_ilvA_R and inserted in the ilvA gene fragment in pKR21 by overlap extension PCR cloning to yield pKR21.3 (32).…”