scholarly journals Molecular Evolution of β-Lactam-Resistant Haemophilus influenzae: 9-Year Surveillance of Penicillin-Binding Protein 3 Mutations in Isolates from Japan

2006 ◽  
Vol 50 (7) ◽  
pp. 2487-2492 ◽  
Author(s):  
Yumiko Sanbongi ◽  
Takahisa Suzuki ◽  
Yumi Osaki ◽  
Nami Senju ◽  
Takashi Ida ◽  
...  
Keyword(s):  
Amino Acid ◽  
Molecular Evolution ◽  
Haemophilus Influenzae ◽  
Clavulanic Acid ◽  
Antimicrobial Agents ◽  
Binding Protein ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein ◽  
Amoxicillin Clavulanic Acid ◽  
Second Period

ABSTRACT A total of 621 clinical isolates of Haemophilus influenzae collected in Japan between 1995 and 2003 were studied for their susceptibilities to several antimicrobial agents, β-lactamase production, and amino acid substitutions in penicillin-binding protein 3 (PBP 3). Over the four study periods (first period, 1995 to 1996; second period, 1997 to 1998; third period, 2000 to 2001; fourth period, 2002 to 2003), the susceptibilities to β-lactam agents decreased and the incidence of isolates with substitutions at positions 377, 385, 389, 517, and/or 526 in PBP 3 increased from 28.8% to 52.0%. Five hundred seventy-one β-lactamase-nonproducing isolates were grouped into 18 classes, based on the pattern of the five mutations in PBP 3. The Asp526Lys substitution led to 6.0-, 4.3-, 2.4-, and 5.4-fold increases in amoxicillin-clavulanic acid, cefdinir, cefditoren, and faropenem resistance, respectively. PBP 3 with multiple substitutions (Met377Ile, Ser385Thr, and/or Leu389Phe) together with Asp526Lys resulted in increased resistance compared to that for PBP 3 with the Asp526Lys substitution alone. These results indicate that mutations at these five positions increased resistance to most β-lactams. Although a significant change in the prevalence of β-lactamase-producing strains was not observed, the proportions of those possessing both PBP 3 alterations and β-lactamase production have slightly increased (from 1.4% to 5.0%). The ROB-1 β-lactamase was rare, but this is the first report of this β-lactamase in Japan.

scholarly journals Association of Amino Acid Substitutions in Penicillin-Binding Protein 3 with β-Lactam Resistance in β-Lactamase-Negative Ampicillin-Resistant Haemophilus influenzae

2001 ◽  
Vol 45 (6) ◽  
pp. 1693-1699 ◽  
Author(s):  
Kimiko Ubukata ◽  
Yumi Shibasaki ◽  
Kentarou Yamamoto ◽  
Naoko Chiba ◽  
Keiko Hasegawa ◽  
...  
Keyword(s):  
Amino Acid ◽  
Haemophilus Influenzae ◽  
Binding Protein ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein ◽  
Gene Encoding ◽  
Group Iii ◽  
Peptidoglycan Synthesis ◽  
Development Of Resistance ◽  
Group I

ABSTRACT The affinity of [3H]benzylpenicillin for penicillin-binding protein (PBP) 3A was reduced in 25 clinical isolates of β-lactamase-negative ampicillin (AMP)-resistant (BLNAR)Haemophilus influenzae for which the AMP MIC was ≥1.0 μg/ml. The affinities of PBP 3B and PBP 4 were also reduced in some strains. The sequences of the ftsI gene encoding the transpeptidase domain of PBP 3A and/or PBP 3B and of thedacB gene encoding PBP 4 were determined for these strains and compared to those of AMP-susceptible Rd strains. The BLNAR strains were classified into three groups on the basis of deduced amino acid substitutions in the ftsI gene, which is thought to be involved in septal peptidoglycan synthesis. His-517, near the conserved Lys-Thr-Gly (KTG) motif, was substituted for Arg-517 in group I strains (n = 9), and Lys-526 was substituted for Asn-526 in group II strains (n = 12). In group III strains (n = 4), three residues (Met-377, Ser-385, and Leu-389), positioned near the conserved Ser-Ser-Asn (SSN) motif, were replaced with Ile, Thr, and Phe, respectively, in addition to the replacement with Lys-526. The MICs of cephem antibiotics with relatively high affinities for PBP 3A and PBP 3B were higher than those of AMP and meropenem for group III strains. The MICs of β-lactams forH. influenzae transformants into which the ftsIgene from BLNAR strains was introduced were as high as those for the donors, and PBP 3A and PBP 3B showed decreased affinities for β-lactams. There was no clear relationship between 7-bp deletions in the dacB gene and AMP susceptibility. Even though mutations in another gene(s) may be involved in β-lactam resistance, these data indicate that mutations in the ftsI gene are the most important for development of resistance to β-lactams in BLNAR strains.

scholarly journals Diversity of β-Lactam Resistance-Conferring Amino Acid Substitutions in Penicillin-Binding Protein 3 of Haemophilus influenzae

2002 ◽  
Vol 46 (7) ◽  
pp. 2208-2218 ◽  
Author(s):  
Henri Dabernat ◽  
Catherine Delmas ◽  
Martine Seguy ◽  
Roseline Pelissier ◽  
Genevieve Faucon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Haemophilus Influenzae ◽  
Binding Protein ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein ◽  
Gene Encoding ◽  
Peptidoglycan Synthesis ◽  
Group I ◽  
Adults And Children

ABSTRACT 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 β-lactam antibiotics with or without β-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 β-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 β-lactam, brought about by mutations of the ftsI gene, is becoming a frequent phenomenon, affecting both strains that produce β-lactamase and those that do not. The level of resistance remains low but opens the way to greater resistance in the future.

scholarly journals Amino Acid Substitutions in Mosaic Penicillin-Binding Protein 2 Associated with Reduced Susceptibility to Cefixime in Clinical Isolates of Neisseria gonorrhoeae

2006 ◽  
Vol 50 (11) ◽  
pp. 3638-3645 ◽  
Author(s):  
Sho Takahata ◽  
Nami Senju ◽  
Yumi Osaki ◽  
Takuji Yoshida ◽  
Takashi Ida
Keyword(s):  
Amino Acid ◽  
Neisseria Gonorrhoeae ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Complete Sequence ◽  
Clinical Isolates ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein ◽  
Fourfold Increase ◽  
Genes Encoding

ABSTRACT The molecular mechanisms of reduced susceptibility to cefixime in clinical isolates of Neisseria gonorrhoeae, particularly amino acid substitutions in mosaic penicillin-binding protein 2 (PBP2), were examined. The complete sequence of ponA, penA, and por genes, encoding, respectively, PBP1, PBP2, and porin, were determined for 58 strains isolated in 2002 from Japan. Replacement of leucine 421 by proline in PBP1 and the mosaic-like structure of PBP2 were detected in 48 strains (82.8%) and 28 strains (48.3%), respectively. The presence of mosaic PBP2 was the main cause of the elevated cefixime MIC (4- to 64-fold). In order to identify the mutations responsible for the reduced susceptibility to cefixime in isolates with mosaic PBP2, penA genes with various mutations were transferred to a susceptible strain by genetic transformation. The susceptibility of partial recombinants and site-directed mutants revealed that the replacement of glycine 545 by serine (G545S) was the primary mutation, which led to a two- to fourfold increase in resistance to cephems. Replacement of isoleucine 312 by methionine (I312M) and valine 316 by threonine (V316T), in the presence of the G545S mutation, reduced susceptibility to cefixime, ceftibuten, and cefpodoxime by an additional fourfold. Therefore, three mutations (G545S, I312M, and V316T) in mosaic PBP2 were identified as the amino acid substitutions responsible for reduced susceptibility to cefixime in N. gonorrhoeae.

scholarly journals Contribution of Specific Amino Acid Changes in Penicillin Binding Protein 1 to Amoxicillin Resistance in ClinicalHelicobacter pyloriisolates

2010 ◽  
Vol 55 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Nadia N. Qureshi ◽  
Dimitrios Morikis ◽  
Neal L. Schiller
Keyword(s):  
Amino Acid ◽  
Homology Modeling ◽  
Binding Protein ◽  
Site Directed Mutagenesis ◽  
Amino Acid Substitutions ◽  
Peptic Ulcers ◽  
Penicillin Binding Protein ◽  
Specific Amino Acid ◽  
Binding Cleft ◽  
H Pylori

ABSTRACTAmoxicillin is commonly used to treatHelicobacter pylori, a major cause of peptic ulcers, stomach cancer, and B-cell mucosa-associated lymphoid tissue lymphoma. Amoxicillin resistance inH. pyloriis increasing steadily, especially in developing countries, leading to treatment failures. In this study, we characterize the mechanism of amoxicillin resistance in the U.S. clinical isolate B258. Transformation of amoxicillin-susceptible strain 26695 with the penicillin binding protein 1 gene (pbp1) from B258 increased the amoxicillin resistance of 26695 to equal that of B258, while studies using biotinylated amoxicillin showed a decrease in the binding of amoxicillin to the PBP1 of B258. Transformation with 4pbp1fragments, each encompassing several amino acid substitutions, combined with site-directed mutagenesis studies, identified 3 amino acid substitutions in PBP1 of B258 which affected amoxicillin susceptibility (Val 469 Met, Phe 473 Leu, and Ser 543 Arg). Homology modeling showed the spatial orientation of these specific amino acid changes in PBP1 from 26695 and B258. The results of these studies demonstrate that amoxicillin resistance in the clinical U.S. isolate B258 is due solely to an altered PBP1 protein with a lower binding affinity for amoxicillin. Homology modeling analyses using previously identified amino acid substitutions of amoxicillin-resistant PBP1s demonstrate the importance of specific amino acid substitutions in PBP1 that affect the binding of amoxicillin in the putative binding cleft, defining those substitutions deemed most important in amoxicillin resistance.

scholarly journals Identification of different clonal complexes and diverse amino acid substitutions in penicillin-binding protein 2 (PBP2) associated with borderline oxacillin resistance in Canadian Staphylococcus aureus isolates

2006 ◽  
Vol 55 (12) ◽  
pp. 1675-1683 ◽  
Author(s):  
Jeya Nadarajah ◽  
Mark J. S. Lee ◽  
Lisa Louie ◽  
Latha Jacob ◽  
Andrew E. Simor ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Amino Acid ◽  
Binding Protein ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein ◽  
Clonal Type ◽  
Amino Acid Sequence Variation ◽  
Oxacillin Resistance ◽  
Relationship Of ◽  
The Relationship

Borderline oxacillin-resistant Staphylococcus aureus (BORSA) exhibit oxacillin MIC values of 1–8 μg ml−1, but lack mecA, which encodes the low-affinity penicillin-binding protein (PBP)2a. The relationship of the BORSA phenotype with specific genetic backgrounds was assessed, as well as amino acid sequence variation in the normal PBP2. Among 38 BORSA, 26 had a common PFGE profile of genomic DNA, and were multilocus sequence type (ST)25. The other isolates were genetically diverse. Complete pbp2 sequences were determined for three BORSA, corresponding to ST25, ST1 and ST47, which were selected on the basis of lacking blaZ-encoded β-lactamase. The essential transpeptidase-domain-encoding segment of pbp2 was also sequenced from seven additional ST25 isolates. Amino acid substitutions occurred in the transpeptidase domain of all BORSA, irrespective of clonal type. A Gln629→Pro substitution was common to all ST25 BORSA, but most could be distinguished from one another by additional unique substitutions in the transpeptidase domain. The ST1 and ST47 isolates also possessed unique substitutions in the transpeptidase domain. Plasmid-mediated expression of pbp2 from an ST25 or ST1 isolate in S. aureus RN6390 increased its oxacillin MIC from 0.25 to 4 μg ml−1, while pbp2 from a susceptible strain, ATCC 25923, had no effect. Therefore, different amino acid substitutions in PBP2 of diverse BORSA lineages contribute to borderline resistance. The predominant ST25 lineage was not related to any of the five clonal complexes that contain meticillin-resistant S. aureus (MRSA), suggesting that ST25 cannot readily acquire mecA-mediated resistance.

scholarly journals Antibiotic Resistance in Haemophilus influenzae Decreased, except for β-Lactamase-Negative Amoxicillin-Resistant Isolates, in Parallel with Community Antibiotic Consumption in Spain from 1997 to 2007

2008 ◽  
Vol 52 (8) ◽  
pp. 2760-2766 ◽  
Author(s):  
Silvia García-Cobos ◽  
José Campos ◽  
Emilia Cercenado ◽  
Federico Román ◽  
Edurne Lázaro ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Haemophilus Influenzae ◽  
Clavulanic Acid ◽  
Antimicrobial Agents ◽  
Geographic Area ◽  
Antibiotic Consumption ◽  
Control Group ◽  
Promoter Regions ◽  
Geometric Means ◽  
Amoxicillin Clavulanic Acid

ABSTRACT The susceptibility to 14 antimicrobial agents and the mechanisms of aminopenicillin resistance were studied in 197 clinical isolates of Haemophilus influenzae—109 isolated in 2007 (study group) and 88 isolated in 1997 (control group). Community antibiotic consumption trends were also examined. H. influenzae strains were consecutively isolated from the same geographic area, mostly from respiratory specimens from children and adults. Overall, amoxicillin resistance decreased by 8.4% (from 38.6 to 30.2%). β-Lactamase production decreased by 15.6% (from 33 to 17.4%, P = 0.01), but amoxicillin resistance without β-lactamase production increased by 7.1% (from 5.7 to 12.8%). All β-lactamase-positive isolates were TEM-1, but five different promoter regions were identified, with Pdel being the most prevalent in both years, and Prpt being associated with the highest amoxicillin resistance. A new promoter consisting of a double repeat of 54 bp was detected. Community consumption of most antibiotics decreased, as did the geometric means of their MICs, but amoxicillin-clavulanic acid and azithromycin consumption increased by ca. 60%. For amoxicillin-clavulanic acid, a 14.2% increase in the population with an MIC of 2 to 4 μg/ml (P = 0.02) was observed; for azithromycin, a 21.2% increase in the population with an MIC of 2 to 8 μg/ml (P = 0.0005) was observed. In both periods, the most common gBLNAR (i.e., H. influenzae isolates with mutations in the ftsI gene as previously defined) patterns were IIc and IIb. Community consumption of trimethoprim-sulfamethoxazole decreased by 54%, while resistance decreased from 50 to 34.9% (P = 0.04). Antibiotic resistance in H. influenzae decreased in Spain from 1997 to 2007, but surveillance should be maintained since new forms of resistances may be developing.

scholarly journals Resistance Mechanisms in an In Vitro-Selected Amoxicillin-Resistant Strain of Helicobacter pylori

2006 ◽  
Vol 50 (12) ◽  
pp. 4174-4176 ◽  
Author(s):  
Edgie-Mark A. Co ◽  
Neal L. Schiller
Keyword(s):  
Helicobacter Pylori ◽  
Amino Acid ◽  
Resistant Strain ◽  
Binding Protein ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein

ABSTRACT We investigated the β-lactam resistance mechanism(s) of an in vitro-selected amoxicillin-resistant Helicobacter pylori strain (AmoxR). Our results demonstrated that resistance is due to a combination of amino acid substitutions in penicillin binding protein 1 (PBP1), HopB, and HopC identified in AmoxR, resulting in decreased affinity of PBP1 for amoxicillin and decreased accumulation of penicillin.

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