title: Role of inter-species recombination of the ftsI gene in the dissemination of altered penicillin-binding-protein-3-mediated resistance in Haemophilus influenzae and Haemophilus haemolyticus.
abstract: OBJECTIVE
  To screen the ftsI gene sequences obtained from clinical isolates of non-typeable Haemophilus influenzae (NTHi) and Haemophilus haemolyticus for the presence of mosaic ftsI gene structures, and to evaluate the role of inter-species recombination of the ftsI gene in the formation and distribution of resistant ftsI genes.
  
  
  METHODS
  The ftsI genes of 100 Haemophilus isolates comprising genetically defined β-lactamase-negative ampicillin-susceptible (gBLNAS), β-lactamase-positive ampicillin-resistant (gBLPAR), β-lactamase-negative ampicillin-resistant (gBLNAR) and β-lactamase-positive amoxicillin/clavulanate-resistant (gBLPACR) isolates of NTHi (n = 50) and H. haemolyticus (n = 50) were analysed in this study. Both the flanking regions and the full-length ftsI gene sequences of all study isolates were screened for mosaic structures using H. influenzae Rd and H. haemolyticus ATCC 33390 as reference parental sequences, and bioinformatics methods were used for recombination analysis using SimPlot.
  
  
  RESULTS
  Of the 100 clinical isolates analysed 34% (34/100) harboured mosaic ftsI gene structures containing distinct ftsI gene fragments similar to both reference parental sequences. The inter-species recombination events were exclusively encountered in the ftsI gene of gBLNAR/gBLPACR isolates of both NTHi and H. haemolyticus, and were always associated with the formation of a mosaic fragment at the 3' end of the ftsI gene. There was no evidence supporting horizontal gene transfer (HGT) involving the entire ftsI gene among the clinical isolates in vivo.
  
  
  CONCLUSIONS
  We provide evidence for the HGT and inter-species recombination of the ftsI gene among gBLNAR/gBLPACR isolates of NTHi and H. haemolyticus in a clinical setting, highlighting the importance of recombination of the ftsI gene in the emergence of altered penicillin-binding protein 3 and BLNAR-mediated resistance.
authors.affiliation: School of Human Life Sciences, University of Tasmania, Launceston, Tasmania, Australia elizabeth.witherden@utas.edu.au.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Witherden
authors.affiliation: Department of Infectious Disease, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal.
authors.forename: Maria Paula
authors.initials: MP
authors.lastname: Bajanca-Lavado
authors.affiliation: School of Human Life Sciences, University of Tasmania, Launceston, Tasmania, Australia.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Tristram
authors.affiliation: Department of Infectious Disease, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Nunes
mesh_terms: D006190:Haemophilus / Q000187:drug effects* / Q000235:genetics*; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D010403:Penicillin Resistance / Q000235:genetics*; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D011995:Recombination, Genetic
chemical_list: D046915:Penicillin-Binding Proteins
keywords: BLNAR; horizontal gene transfer; mosaic genes; β-lactam resistance