title: Emergence of clonally related multidrug resistant Haemophilus influenzae with penicillin-binding protein 3-mediated resistance to extended-spectrum cephalosporins, Norway, 2006 to 2013.
abstract: Resistance to cephalosporins in Haemophilus influenzae is usually caused by characteristic alterations in penicillin-binding protein 3 (PBP3), encoded by the ftsI gene. Resistance to extended-spectrum cephalosporins is associated with high-level PBP3-mediated resistance (high-rPBP3), defined by the second stage S385T substitution in addition to a first stage substitution (R517H or N526K). The third stage L389F substitution is present in some high-rPBP3 strains. High-rPBP3 H. influenzae are considered rare outside Japan and Korea. In this study, 30 high-rPBP3 isolates from Norway, collected between 2006 and 2013, were examined by serotyping, multilocus sequence typing (MLST), ftsI sequencing, detection of beta-lactamase genes and minimum inhibitory concentration (MIC) determination. MICs were interpreted according to clinical breakpoints from the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Respiratory isolates predominated (proportion: 24/30). The 30 isolates included one serotype f isolate, while the remaining 29 lacked polysaccharide capsule genes. Resistance to extended-spectrum cephalosporins (cefixime, 29 isolates/30 isolates; cefepime, 28/30; cefotaxime, 26 /30; ceftaroline, 26/30; ceftriaxone, 14/30), beta-lactamase production (11/30) and co-resistance to non-beta-lactams (trimethoprim-sulfamethoxazole, 13/30; tetracycline, 4/30; chloramphenicol, 4/30; ciprofloxacin, 3/30) was frequent. The N526K substitution in PBP3 was present in 23 of 30 isolates; these included a blood isolate which represents the first invasive S385T + N526K isolate reported from Europe. The L389F substitution, present in 16 of 30 isolates, coincided with higher beta-lactam MICs. Non-susceptibility to meropenem was frequent in S385T + L389F + N526K isolates (8/12). All 11 beta-lactamase positive isolates were TEM-1. Five clonal groups of two to 10 isolates with identical MLST-ftsI allelic profiles were observed, including the first reported high-rPBP3 clone with TEM-1 beta-lactamase and co-resistance to ciprofloxacin, tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole. Prior to this study, no multidrug resistant high-rPBP3 H. influenzae had been reported in Norway. Intensified surveillance of antimicrobial resistance is needed to guide empiric therapy.
authors.affiliation: Department of Microbiology, Vestfold Hospital Trust, Tonsberg, Norway.
authors.forename: D
authors.initials: D
authors.lastname: Skaare
authors.forename: I L
authors.initials: IL
authors.lastname: Anthonisen
authors.forename: G
authors.initials: G
authors.lastname: Kahlmeter
authors.forename: E
authors.initials: E
authors.lastname: Matuschek
authors.forename: O B
authors.initials: OB
authors.lastname: Natås
authors.forename: M
authors.initials: M
authors.lastname: Steinbakk
authors.forename: A
authors.initials: A
authors.lastname: Sundsfjord
authors.forename: B E
authors.initials: BE
authors.lastname: Kristiansen
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D005838:Genotype; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology; D006193:Haemophilus influenzae / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D009664:Norway / Q000453:epidemiology; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D065288:Serogroup; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D046915:Penicillin-Binding Proteins; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1