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 Genetic Analyses of Penicillin Binding Protein Determinants in Multidrug-Resistant Streptococcus pneumoniae Serogroup 19 CC320/271 Clone with High-Level Resistance to Third-Generation Cephalosporins

2015 ◽  
Vol 59 (7) ◽  
pp. 4040-4045 ◽  
Author(s):  
Margaret Ip ◽  
Irene Ang ◽  
Veranja Liyanapathirana ◽  
Helen Ma ◽  
Raymond Lai
Keyword(s):  
Hong Kong ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Binding Protein ◽  
Multidrug Resistant ◽  
Penicillin Binding Protein ◽  
Unique Amino Acid Substitution ◽  
High Level ◽  
Unique Amino Acid ◽  
Level Resistance

ABSTRACTWe describe the dissemination of a multidrug-resistant (MDR) serogroup 19 pneumococcal clone of representative multilocus sequence type 271 (ST271) with high-level resistance to cefotaxime in Hong Kong and penicillin binding protein (pbp) genes and its relationships to Taiwan19F-14 and the prevalent multidrug-resistant 19A clone (MDR19A-ST320). A total of 472 nonduplicate isolates from 2006 and 2011 were analyzed. Significant increases in the rates of nonsusceptibility to penicillin (PEN) (MIC ≥ 4.0 μg/ml; 9.9 versus 23.3%;P= 0.0005), cefotaxime (CTX) (MIC ≥ 2.0 μg/ml; 12.2 versus 30.3%;P< 0.0001 [meningitis MIC ≥ 1.0 μg/ml; 30.2 versus 48.7%;P= 0.0001]), and erythromycin (ERY) (69.2 versus 84.0%;P= 0.0003) were noted when rates from 2006 and 2011 were compared. The CTX-resistant isolates with MICs of 8 μg/ml in 2011 were of serotype 19F, belonging to ST271. Analyses of the penicillin binding protein 2x (PBP2x) amino acid sequences in relation to the corresponding sequences of the R6 strain revealed M339F, E378A, M400T, and Y595F substitutions found within the ST271 clone but not present in Taiwan19F-14 or MDR19A. In addition, PBP2bs of ST271 strains and that of the Taiwan19F-14 clone were characterized by a unique amino acid substitution, E369D, while ST320 possessed the unique amino acid substitution K366N, as does that of MDR19A in the United States. We hypothesize that ST271 originated from the Taiwan19F-14 lineage, which had disseminated in Hong Kong in the early 2000s, and conferred higher-level β-lactam and cefotaxime resistance through acquisitions of 19 additional amino acid substitutions in PBP2b (amino acid [aa] positions 538 to 641) and altered PBP2x via recombination events. The serogroup 19 MDR CC320/271 clone warrants close monitoring to evaluate its effect after the switch to expanded conjugate vaccines.

scholarly journals Alterations in Penicillin-Binding Protein 1A Confer Resistance to β-Lactam Antibiotics in Helicobacter pylori

2002 ◽  
Vol 46 (7) ◽  
pp. 2229-2233 ◽  
Author(s):  
M. M. Gerrits ◽  
D. Schuijffel ◽  
A. A. van Zwet ◽  
E. J. Kuipers ◽  
C. M. J. E. Vandenbroucke-Grauls ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Binding Protein ◽  
Resistance Mechanism ◽  
Fold Increase ◽  
Single Amino Acid ◽  
Penicillin Binding Protein ◽  
H Pylori ◽  
High Level

ABSTRACT Most Helicobacter pylori strains are susceptible to amoxicillin, an important component of combination therapies for H. pylori eradication. The isolation and initial characterization of the first reported stable amoxicillin-resistant clinical H. pylori isolate (the Hardenberg strain) have been published previously, but the underlying resistance mechanism was not described. Here we present evidence that the β-lactam resistance of the Hardenberg strain results from a single amino acid substitution in HP0597, a penicillin-binding protein 1A (PBP1A) homolog of Escherichia coli. Replacement of the wild-type HP0597 (pbp1A) gene of the amoxicillin-sensitive (Amxs) H. pylori strain 1061 by the Hardenberg pbp1A gene resulted in a 100-fold increase in the MIC of amoxicillin. Sequence analysis of pbp1A of the Hardenberg strain, the Amxs H. pylori strain 1061, and four amoxicillin-resistant (Amxr) 1061 transformants revealed a few amino acid substitutions, of which only a single Ser414→Arg substitution was involved in amoxicillin resistance. Although we cannot exclude that mutations in other genes are required for high-level amoxicillin resistance of the Hardenberg strain, this amino acid substitution in PBP1A resulted in an increased MIC of amoxicillin that was almost identical to that for the original Hardenberg strain.

scholarly journals Differential Penicillin-Binding Protein 5 (PBP5) Levels in the Enterococcus faecium Clades with Different Levels of Ampicillin Resistance

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Maria Camila Montealegre ◽  
Jung Hyeob Roh ◽  
Meredith Rae ◽  
Milya G. Davlieva ◽  
Kavindra V. Singh ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Binding Protein ◽  
Mrna Levels ◽  
Nucleotide Polymorphisms ◽  
Penicillin Binding Protein ◽  
Ampicillin Resistance ◽  
Content Type ◽  
Protein Levels ◽  
Clade B ◽  
Wide Range

ABSTRACT Ampicillin resistance in Enterococcus faecium is a serious concern worldwide, complicating the treatment of E. faecium infections. Penicillin-binding protein 5 (PBP5) is considered the main ampicillin resistance determinant in E. faecium. The three known E. faecium clades showed sequence variations in the pbp5 gene that are associated with their ampicillin resistance phenotype; however, these changes alone do not explain the array of resistance levels observed among E. faecium clinical strains. We aimed to determine if the levels of PBP5 are differentially regulated between the E. faecium clades, with the hypothesis that variations in PBP5 levels could help account for the spectrum of ampicillin MICs seen in E. faecium. We studied pbp5 mRNA levels and PBP5 protein levels as well as the genetic environment upstream of pbp5 in 16 E. faecium strains that belong to the different E. faecium clades and for which the ampicillin MICs covered a wide range. Our results found that pbp5 and PBP5 levels are increased in subclade A1 and A2 ampicillin-resistant strains compared to those in clade B and subclade A2 ampicillin-susceptible strains. Furthermore, we found evidence of major clade-associated rearrangements in the region upstream of pbp5, including large DNA fragment insertions, deletions, and single nucleotide polymorphisms, that may be associated with the differential regulation of PBP5 levels between the E. faecium clades. Overall, these findings highlight the contribution of the clade background to the regulation of PBP5 abundance and point to differences in the region upstream of pbp5 as likely contributors to the differential expression of ampicillin resistance.

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