title: Genetic diversity of the ftsI gene in β-lactamase-nonproducing ampicillin-resistant and β-lactamase-producing amoxicillin-/clavulanic acid-resistant nasopharyngeal Haemophilus influenzae strains isolated from children in South Korea.
abstract: Haemophilus influenzae frequently colonizes the nasopharynx of children and adults, which can lead to a variety of infections. We investigated H. influenzae carriage in the nasopharynx of 360 children, in terms of (1) the prevalence of strains with decreased susceptibility, and (2) the presence of amino acid substitutions in PBP3. One hundred twenty-three strains were isolated (34.2%, 123/360), 122 of which were classified as nontypable H. influenzae (NTHi). Of these, β-lactamase-nonproducing ampicillin-susceptible strains accounted for 26.2%, β-lactamase-producing-ampicillin-resistant strains for 9.0%, β-lactamase-nonproducing ampicillin-resistant (BLNAR) strains for 40.2%, and β-lactamase-producing amoxicillin-/clavulanic acid-resistant (BLPACR) for 24.6%, respectively. Pulsed field gel electrophoresis (PFGE) patterns were so diverse that they were clustered into 41 groups. The amino acid substitutions in the transpeptidase domain (292 amino acids) of ftsI in BLNAR isolates showed that group IIb accounted for 30.6%, IIc for 8.2%, IId for 16.3%, III for 32.7%, and the others for 12.2%. Moreover, groups IIb (56.7%; 17/30) and III (23.3%; 7/30) were prevalent among BLPACR strains. They were subclassified into more diverse sequence subtypes by analysis of the entire PBP3 (610 amino acids). Groups IIb, IIc, IId, and III exhibited 13, four, six, and four sequence subtypes, respectively. Such a genetic diversity is likely indicative of significant potential for decreased antimicrobial susceptibility in nasopharyngeal-colonizing NTHi strains.
authors: Vaccine Bio Research Institute, The Catholic University of Korea, Seoul, Republic of Korea.
authors: Chulmin
authors: C
authors: Park
authors: Kyung-Hyo
authors: KH
authors: Kim
authors: Na-Young
authors: NY
authors: Shin
authors: Ji-Hyun
authors: JH
authors: Byun
authors: Eun-Young
authors: EY
authors: Kwon
authors: Jae-Wook
authors: JW
authors: Lee
authors: Hyo Jin
authors: HJ
authors: Kwon
authors: Eu Yoon
authors: EY
authors: Choi
authors: Dong-Gun
authors: DG
authors: Lee
authors: Woo Yun
authors: WY
authors: Sohn
authors: Jin Han
authors: JH
authors: Kang
mesh_terms: D019943:Amino Acid Substitution; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002675:Child, Preschool; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D006192:Haemophilus Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D009305:Nasopharynx / Q000382:microbiology*; D056910:Republic of Korea / Q000453:epidemiology; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D019980:Amoxicillin-Potassium Clavulanate Combination; D000667:Ampicillin; D001618:beta-Lactamases