Multiple changes of penicillin-binding proteins in penicillin-resistant clinical isolates of Streptococcus pneumoniae.

ABSTRACTAlterations in penicillin-binding proteins, the target enzymes for β-lactam antibiotics, are recognized as primary penicillin resistance mechanisms inStreptococcus pneumoniae. Few studies have analyzed penicillin resistance at the genome scale, however, and we report the sequencing ofS. pneumoniaeR6 transformants generated while reconstructing the penicillin resistance phenotypes from three penicillin-resistant clinical isolates by serial genome transformation. The genome sequences of the three last-level transformants T2-18209, T5-1983, and T3-55938 revealed that 16.2 kb, 82.7kb, and 137.2 kb of their genomes had been replaced with 5, 20, and 37 recombinant sequence segments derived from their respective parental clinical isolates, documenting the extent of DNA transformation between strains. A role in penicillin resistance was confirmed for some of the mutations identified in the transformants. Several multiple recombination events were also found to have happened at single loci coding for penicillin-binding proteins (PBPs) that increase resistance. Sequencing of the transformants with MICs for penicillin similar to those of the parent clinical strains confirmed the importance of mosaic PBP2x, -2b, and -1a as a driving force in penicillin resistance. A role in resistance for mosaic PBP2a was also observed for two of the resistant clinical isolates.

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Identical Penicillin-Binding Domains in Penicillin-Binding Proteins of Streptococcus pneumoniae Clinical Isolates with Different Levels of β-Lactam Resistance

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.7.2895-2902.2005 ◽

2005 ◽

Vol 49 (7) ◽

pp. 2895-2902 ◽

Cited By ~ 32

Author(s):

Laurent Chesnel ◽

Raphaël Carapito ◽

Jacques Croizé ◽

Otto Dideberg ◽

Thierry Vernet ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Binding Proteins ◽

Laboratory Strain ◽

Clinical Isolates ◽

Penicillin G ◽

Resistance Level ◽

Penicillin Binding Proteins ◽

Binding Domains ◽

Wide Range ◽

Genes Encoding

ABSTRACT We have sequenced the penicillin-binding domains of the complete repertoire of penicillin-binding proteins and MurM from 22 clinical isolates of Streptococcus pneumoniae that span a wide range of β-lactam resistance levels. Evidence of mosaicism was found in the genes encoding PBP 1a, PBP 2b, PBP 2x, MurM, and, possibly, PBP 2a. Five isolates were found to have identical PBP and MurM sequences, even though the MICs for penicillin G ranged from 0.25 to 2.0 mg/liter. When the sequences encoding PBP 1a, PBP 2b, and PBP 2x from one of these isolates were used to transform laboratory strain R6, the resulting strain had a resistance level higher than that of the less resistant isolates carrying that PBP set but lower than that of the most resistant isolates carrying that PBP set. This result demonstrates that if the R6 strain is arbitrarily defined as the standard genotype, some wild genetic backgrounds can either increase or decrease the PBP-based resistance phenotype.

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Activities of Ceftobiprole and Other β-Lactams against Streptococcus pneumoniae Clinical Isolates from the United States with Defined Substitutions in Penicillin-Binding Proteins PBP 1a, PBP 2b, and PBP 2x

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00238-06 ◽

2006 ◽

Vol 50 (7) ◽

pp. 2530-2532 ◽

Cited By ~ 32

Author(s):

Todd A. Davies ◽

Wenchi Shang ◽

Karen Bush

Keyword(s):

United States ◽

Streptococcus Pneumoniae ◽

Binding Proteins ◽

Binding Protein ◽

The United States ◽

Clinical Isolates ◽

Resistant Isolate ◽

Penicillin Binding Protein ◽

Penicillin Binding Proteins

ABSTRACT The activities of ceftobiprole and other β-lactams were examined with 30 Streptococcus pneumoniae isolates containing multiple pbp1a, pbp2b, and pbp2x mutations. The highest ceftobiprole MIC was 1 μg/ml, while the comparator MICs were 16 to 64 μg/ml. Fifty percent inhibitory concentrations for penicillin-binding protein 2x were 0.5 μg/ml (ceftobiprole) and 4 μg/ml (ceftriaxone) in a penicillin- and ceftriaxone-resistant isolate.

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Penicillin-binding proteins 2b and 2x of Streptococcus pneumoniae are primary resistance determinants for different classes of beta-lactam antibiotics.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.4.829 ◽

1996 ◽

Vol 40 (4) ◽

pp. 829-834 ◽

Cited By ~ 169

Author(s):

T Grebe ◽

R Hakenbeck

Keyword(s):

Streptococcus Pneumoniae ◽

Clinical Isolate ◽

Binding Proteins ◽

Point Mutations ◽

Clinical Isolates ◽

Single Amino Acid ◽

Beta Lactam ◽

Penicillin Binding Proteins ◽

Beta Lactam Antibiotics ◽

High Level

High-level resistance to beta-lactam antibiotics in Streptococcus pneumoniae is mediated by successive alterations in essential penicillin-binding proteins (PBPs). In the present work, single amino acid changes in S. pneumoniae PBP 2x and PBP 2b that result in reduced affinity for the antibiotic and that confer first-level beta-lactam resistance are defined. Point mutations in the PBP genes were generated by PCR-derived mutagenesis. Those conferring maximal resistance to either cefotaxime (pbp2x) or piperacillin (pbp2b) were obtained after transformation of the susceptible laboratory strain R6 with the PCR-amplified PBP genes and selection on agar with various concentrations of the antibiotic. In the case of PBP 2x, transformants for which the cefotaxime MIC was 0.16 microgram/ml contained the substitution of a Thr for an Ala at position 550 (Thr550-->Ala), close to the PBP homology box Lys547SerGly, a mutation frequently observed in laboratory mutants and in a high-level cefotaxime-resistant clinical isolate as well. After further selection, transformants resisting 0.3 microgram of cefotaxime per ml were obtained; they contained the substitution Gly550 as the result of two mutations in the same codon. In PBP 2b, Thr446-->Ala, adjacent to another homology box Ser443SerAsn, was the mutation selected with piperacillin. This substitution has been described in all clinical isolates with a low-affinity PBP 2b but was distinct from point mutations found in laboratory mutants. Both pbp2b with the single mutation and a mosaic pbp2b of a clinical isolate conferred a twofold increase in piperacillin resistance. Attempts to select PBP 2b variants at higher piperacillin concentrations were unsuccessful. The mutated PBP 2b also markedly reduced the lytic response to piperacillin, suggesting that such a mutation is an important step in resistance development in clinical isolates.

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Increasing Ceftriaxone Resistance and Multiple Alterations of Penicillin-Binding Proteins among Penicillin-Resistant Streptococcus pneumoniae Isolates in Taiwan

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01563-06 ◽

2007 ◽

Vol 51 (9) ◽

pp. 3404-3406 ◽

Cited By ~ 20

Author(s):

Cheng-Hsun Chiu ◽

Lin-Hui Su ◽

Yhu-Chering Huang ◽

Jui-Chia Lai ◽

Hsiu-Ling Chen ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Amino Acid ◽

Binding Proteins ◽

Binding Protein ◽

Penicillin Binding Protein ◽

Penicillin Binding Proteins

ABSTRACT The rate of nonsusceptibility of penicillin-resistant Streptococcus pneumoniae strains to ceftriaxone increased significantly in Taiwan in 2005. Approximately 90% of the ceftriaxone-nonsusceptible isolates were found to be of four major serotypes (serotypes 6B, 14, 19F, and 23F). Seven amino acid alterations in the penicillin-binding protein 2B transpeptidase-encoding region specifically contributed to the resistance.

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beta-Lactam resistance in Streptococcus pneumoniae: penicillin-binding proteins and non-penicillin-binding proteins

Molecular Microbiology ◽

10.1046/j.1365-2958.1999.01521.x ◽

1999 ◽

Vol 33 (4) ◽

pp. 673-678 ◽

Cited By ~ 97

Author(s):

Regine Hakenbeck ◽

Thorsten Grebe ◽

Dorothea Zahner ◽

Jeffry B. Stock

Keyword(s):

Streptococcus Pneumoniae ◽

Binding Proteins ◽

Beta Lactam ◽

Penicillin Binding Proteins

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PURIFICATION OF PENICILLIN BINDING PROTEINS FROM STREPTOCOCCUS PNEUMONIAE

The Target of Penicillin ◽

10.1515/9783110866544-063 ◽

1983 ◽

pp. 415-420 ◽

Cited By ~ 4

Keyword(s):

Streptococcus Pneumoniae ◽

Binding Proteins ◽

Penicillin Binding Proteins

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Capsule Homology Does Not Increase the Frequency of Transformation of Linked Penicillin Binding Proteins PBP 1a and PBP 2x in Streptococcus pneumoniae

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.4.1591-1592.2005 ◽

2005 ◽

Vol 49 (4) ◽

pp. 1591-1592 ◽

Cited By ~ 2

Author(s):

Krzysztof Trzciński ◽

Adam MacNeil ◽

Keith P. Klugman ◽

Marc Lipsitch

Keyword(s):

Streptococcus Pneumoniae ◽

Binding Proteins ◽

Penicillin Resistance ◽

Penicillin Binding Proteins ◽

Transformation Rates

ABSTRACT Penicillin resistance is mainly confined to a limited number of Streptococcus pneumoniae serotypes. Given linkage between the capsular biosynthesis locus and two penicillin binding proteins, we tested whether capsule homology increases transformation rates of penicillin resistance. Transformation rates in homologous donor-recipient pairs were no higher than expected, falsifying this hypothesis.

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