Dataset Information

Horizontal gene transfer of ftsI, encoding penicillin-binding protein 3, in Haemophilus influenzae.

ABSTRACT: Horizontal gene transfer has been identified in only a small number of genes in Haemophilus influenzae, an organism which is naturally competent for transformation. This report provides evidence for the genetic transfer of the ftsI gene, which encodes penicillin-binding protein 3, in H. influenzae. Mosaic structures of the ftsI gene were found in several clinical isolates of H. influenzae. To identify the origin of the mosaic sequence, complete sequences of the corresponding gene from seven type strains of Haemophilus species were determined. Comparison of these sequences with mosaic regions identified a homologous recombination of the ftsI gene between H. influenzae and Haemophilus haemolyticus. Subsequently, ampicillin-resistant H. influenzae strains harboring identical ftsI sequences were genotyped by pulsed-field gel electrophoresis (PFGE). Divergent PFGE patterns among beta-lactamase-nonproducing ampicillin-resistant (BLNAR) strains from different hospitals indicated the potential for the genetic transfer of the mutated ftsI gene between these isolates. Moreover, transfer of the ftsI gene from BLNAR strains to beta-lactamase-nonproducing ampicillin-susceptible (BLNAS) H. influenzae strains was evaluated in vitro. Coincubation of a BLNAS strain (a rifampin-resistant mutant of strain Rd) and BLNAR strains resulted in the emergence of rifampin- and cefdinir-resistant clones at frequencies of 5.1 x 10(-7) to 1.5 x 10(-6). Characterization of these doubly resistant mutants by DNA sequencing of the ftsI gene, susceptibility testing, and genotyping by PFGE revealed that the ftsI genes of BLNAR strains had transferred to BLNAS strains during coincubation. In conclusion, horizontal transfer of the ftsI gene in H. influenzae can occur in an intraspecies and an interspecies manner.

SUBMITTER: Takahata S

PROVIDER: S-EPMC1855551 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Horizontal gene transfer of ftsI, encoding penicillin-binding protein 3, in Haemophilus influenzae.

Takahata Sho S Ida Takashi T Senju Nami N Sanbongi Yumiko Y Miyata Aiko A Maebashi Kazunori K Hoshiko Shigeru S

Antimicrobial agents and chemotherapy 20070226 5

Horizontal gene transfer has been identified in only a small number of genes in Haemophilus influenzae, an organism which is naturally competent for transformation. This report provides evidence for the genetic transfer of the ftsI gene, which encodes penicillin-binding protein 3, in H. influenzae. Mosaic structures of the ftsI gene were found in several clinical isolates of H. influenzae. To identify the origin of the mosaic sequence, complete sequences of the corresponding gene from seven type ...[more]

PMID: 17325223

Similar Datasets

Project description:BACKGROUND: Beta-lactam resistance in Haemophilus influenzae due to ftsI mutations causing altered penicillin-binding protein 3 (PBP3) is increasing worldwide. Low-level resistant isolates with the N526K substitution (group II low-rPBP3) predominate in most geographical regions, while high-level resistant isolates with the additional S385T substitution (group III high-rPBP3) are common in Japan and South Korea.Knowledge about the molecular epidemiology of rPBP3 strains is limited. We combined multilocus sequence typing (MLST) and ftsI/PBP3 typing to study the emergence and spread of rPBP3 in nontypeable H. influenzae (NTHi) in Norway. RESULTS: The prevalence of rPBP3 in a population of 795 eye, ear and respiratory isolates (99% NTHi) from 2007 was 15%. The prevalence of clinical PBP3-mediated resistance to ampicillin was 9%, compared to 2.5% three years earlier. Group II low-rPBP3 predominated (96%), with significant proportions of isolates non-susceptible to cefotaxime (6%) and meropenem (20%). Group III high-rPBP3 was identified for the first time in Northern Europe.Four MLST sequence types (ST) with characteristic, highly diverging ftsI alleles accounted for 61% of the rPBP3 isolates. The most prevalent substitution pattern (PBP3 type A) was present in 41% of rPBP3 isolates, mainly carried by ST367 and ST14. Several unrelated STs possessed identical copies of the ftsI allele encoding PBP3 type A.Infection sites, age groups, hospitalization rates and rPBP3 frequencies differed between STs and phylogenetic groups. CONCLUSIONS: This study is the first to link ftsI alleles to STs in H. influenzae. The results indicate that horizontal gene transfer contributes to the emergence of rPBP3 by phylogeny restricted transformation.Clonally related virulent rPBP3 strains are widely disseminated and high-level resistant isolates emerge in new geographical regions, threatening current empiric antibiotic treatment. The need of continuous monitoring of beta-lactam susceptibility and a global system for molecular surveillance of rPBP3 strains is underlined. Combining MLST and ftsI/PBP3 typing is a powerful tool for this purpose.

Project description:Haemophilus influenzae colonizes the respiratory tract in humans and causes both invasive and noninvasive infections. Resistance to extended-spectrum cephalosporins in H. influenzae is rare in Europe. In this study, we defined acquired resistance gene loci and ftsI mutations in multidrug-resistant (MDR) and/or PBP3-mediated beta-lactam-resistant (rPBP3) H. influenzae strains, intending to understand the mode of spread of antibiotic resistance determinants in this species. Horizontal transfer of mobile genetic elements and transformation with resistance-conferring ftsI alleles were contributory. We found one small plasmid and three novel integrative conjugative elements (ICEs) which carry different combinations of resistance genes. Demonstration of transfer and/or ICE circular forms showed that the ICEs are functional. Two extensively MDR genetically unrelated H. influenzae strains (F and G) from the same geographical region shared an identical novel MDR ICE (Tn6686) harboring blaTEM-1, catA2-like, and tet(B). The first Nordic case of MDR H. influenzae septicemia, strain 0, originating from the same geographical area as these strains, had a similar resistance pattern but contained another ICE [Tn6687 with blaTEM-1, catP and tet(B)] with an overall structure quite similar to that of Tn6686. Comparison of the complete ftsI genes among rPBP3 strains revealed that the entire gene or certain regions of it are identical in genetically unrelated strains, indicating horizontal gene transfer. Our findings illustrate that H. influenzae is capable of acquiring resistance against a wide range of commonly used antibiotics through horizontal gene transfer, in terms of conjugative transfer of ICEs and transformation of chromosomal genes.IMPORTANCEHaemophilus influenzae colonizes the respiratory tract in humans and causes both invasive and noninvasive infections. As a threat to treatment, resistance against critically important antibiotics is on the rise in H. influenzae Identifying mechanisms for horizontal acquisition of resistance genes is important to understand how multidrug resistance develops. The present study explores the antimicrobial resistance genes and their context in beta-lactam-resistant H. influenzae with coresistance to up to four non-beta-lactam groups. The results reveal that this organism is capable of acquiring resistance to a wide range of commonly used antibiotics through conjugative transfer of mobile genetic elements and transformation of chromosomal genes, resulting in mosaic genes with a broader resistance spectrum. Strains with chromosomally mediated resistance to extended-spectrum cephalosporins, co-trimoxazole, and quinolones combined with mobile genetic elements carrying genes mediating resistance to ampicillin, tetracyclines, and chloramphenicol have been reported, and further dissemination of such strains represents a particular concern.

Project description:The sequences of the ftsI gene, encoding the transpeptidase domain of penicillin binding protein (PBP) 3A and/or PBP 3B, which are involved in septal peptidoglycan synthesis, were determined for 108 clinical strains of Haemophilus influenzae with reduced susceptibility to beta-lactam antibiotics with or without beta-lactamase production and were compared to those of the ampicillin-susceptible Rd strain and ampicillin-susceptible clinical isolates. The sequences have 18 different mutation patterns and were classified into two groups on the basis of amino acid substitutions deduced from the nucleotide sequences located between bp 960 and 1618 of the ftsI gene. In group I strains (n = 7), His-517 was substituted for Arg-517. In group II strains (n = 101), Lys-526 was substituted for Asn-526. In subgroup IIa (n = 5; H. influenzae ATCC 49247), the only observed substitution was Lys-526 for Asn-526; in subgroup IIb (n = 56), Val-502 was substituted for Ala-502 (n = 13), along with several other substitutions: Asn-350 for Asp-350 (n = 15), Asn-350 for Asp-350 and Glu-490 for Gly-490 (n = 14), and Asn-350 for Asp-350 and Ser-437 for Ala-437 (n = 5). In subgroup IIc (n = 25), Thr-502 was substituted for Ala-502. In subgroup IId, Val-449 was substituted for Ile-449 (n = 15). The MICs of beta-lactam antibiotics for the 108 strains were to 8 to 16 times the MICs for susceptible strains. The strains, isolated from both adults and children, were analyzed for genetic relationship by pulsed-field gel electrophoresis and by determination of ftsI sequence phylogeny. Both analyses revealed the lack of clonality and the heterogeneity of the strains, but some clusters suggest the spread and/or persistence of a limited number of strains of the same pulsotype and pattern of amino acid substitutions. Reduced susceptibility to beta-lactam, brought about by mutations of the ftsI gene, is becoming a frequent phenomenon, affecting both strains that produce beta-lactamase and those that do not. The level of resistance remains low but opens the way to greater resistance in the future.

Dataset Information

Horizontal gene transfer of ftsI, encoding penicillin-binding protein 3, in Haemophilus influenzae.

Publications

Horizontal gene transfer of ftsI, encoding penicillin-binding protein 3, in Haemophilus influenzae.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure