scholarly journals Penicillin-Binding Protein 5 Sequence Alterations in Clinical Isolates of Enterococcus faecium with Different Levels of  -Lactam Resistance

1998 ◽  
Vol 178 (1) ◽  
pp. 159-163 ◽  
Author(s):  
T. Rybkine ◽  
J.-L. Mainardi ◽  
W. Sougakoff ◽  
E. Collatz ◽  
L. Gutmann
Keyword(s):  
Enterococcus Faecium ◽  
Binding Protein ◽  
Clinical Isolates ◽  
Penicillin Binding Protein ◽  
Different Levels

scholarly journals Modification of penicillin-binding protein 5 associated with high-level ampicillin resistance in Enterococcus faecium.

1996 ◽  
Vol 40 (2) ◽  
pp. 354-357 ◽  
Author(s):  
M Ligozzi ◽  
F Pittaluga ◽  
R Fontana
Keyword(s):  
Amino Acid ◽  
Enterococcus Faecium ◽  
Binding Protein ◽  
Point Mutations ◽  
Penicillin Binding Protein ◽  
Ampicillin Resistance ◽  
Resistant Strains ◽  
High Level ◽  
Moderately Resistant ◽  
Different Levels

High-level ampicillin resistance in Enterococcus faecium has been shown to be associated with the synthesis of a modified penicillin-binding protein 5 (PBP 5) which had apparently lost its penicillin-binding capability (R. Fontana, M. Aldegheri, M. Ligozzi, H. Lopez, A. Sucari, and G. Satta. Antimicrob. Agents Chemother. 38:1980-1983, 1994). The pbp5 gene of the highly resistant strain E. faecium 9439 was cloned and sequenced. The deduced amino acid sequence showed 77 and 54% homologies with the PBPs 5 of Enterococcus hirae and Enterococcus faecalis, respectively. A gene fragment coding for the C-terminal part of PBP 5 containing the penicillin-binding domain was also cloned from several E. faecium strains with different levels of ampicillin resistance. Sequence comparison revealed a few point mutations, some of which resulted in amino acid substitutions between SDN and KTG motifs in PBPs 5 of highly resistant strains. One of these converted a polar residue (the T residue at position 562 or 574) of PBP 5 produced by susceptible and moderately resistant strains into a nonpolar one (A or I). This alteration could be responsible for the altered phenotype of PBP 5 in highly resistant strains.

scholarly journals Mosaic-Like Structure of Penicillin-Binding Protein 2 Gene (penA) in Clinical Isolates of Neisseria gonorrhoeae with Reduced Susceptibility to Cefixime

2002 ◽  
Vol 46 (12) ◽  
pp. 3744-3749 ◽  
Author(s):  
Satoshi Ameyama ◽  
Shoichi Onodera ◽  
Masahiro Takahata ◽  
Shinzaburo Minami ◽  
Nobuko Maki ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Neisseria Gonorrhoeae ◽  
Neisseria Meningitidis ◽  
Binding Protein ◽  
Clinical Isolates ◽  
Penicillin Binding Protein ◽  
Gene Sequences ◽  
Neisseria Flavescens ◽  
Neisseria Perflava

ABSTRACT Neisseria gonorrhoeae strains with reduced susceptibility to cefixime (MICs, 0.25 to 0.5 μg/ml) were isolated from male urethritis patients in Tokyo, Japan, in 2000 and 2001. The resistance to cephems including cefixime and penicillin was transferred to a susceptible recipient, N. gonorrhoeae ATCC 19424, by transformation of the penicillin-binding protein 2 gene (penA) that had been amplified by PCR from a strain with reduced susceptibility to cefixime (MIC, 0.5 μg/ml). The sequences of penA in the strains with reduced susceptibilities to cefixime were different from those of other susceptible isolates and did not correspond to the reported N. gonorrhoeae penA gene sequences. Some regions in the transpeptidase-encoding domain in this penA gene were similar to those in the penA genes of Neisseria perflava (N. sicca), Neisseria cinerea, Neisseria flavescens, and Neisseria meningitidis. These results showed that a mosaic-like structure in the penA gene conferred reductions in the levels of susceptibility of N. gonorrhoeae to cephems and penicillin in a manner similar to that found for N. meningitidis and Streptococcus pneumoniae.

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 The VanYD DD-carboxypeptidase of Enterococcus faecium BM4339 is a penicillin-binding protein

Microbiology ◽  
2001 ◽  
Vol 147 (9) ◽  
pp. 2571-2578 ◽  
Author(s):  
Peter E Reynolds ◽  
O. Herman Ambur ◽  
Barbara Casadewall ◽  
Patrice Courvalin
Keyword(s):  
Enterococcus Faecium ◽  
Binding Protein ◽  
Penicillin Binding Protein
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