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Role of penicillin‐binding protein 5 C‐terminal amino acid substitutions in conferring ampicillin resistance in Norwegian clinical strains of Enterococcus faecium
Author(s) -
JUREEN R.,
MOHN S. C.,
HARTHUG S.,
HAARR L.,
LANGELAND N.
Publication year - 2004
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1600-0463.2004.apm11204-0510.x
Subject(s) - biology , penicillin binding proteins , ampicillin , enterococcus faecium , penicillin , norwegian , amp resistance , gene , microbiology and biotechnology , genetics , antibiotics , linguistics , philosophy
The importance of amino acid sequence differences in the C‐terminal part and levels of mRNA expression of penicillin‐binding protein 5 (PBP5) for ampicillin resistance in Enterococcus faecium was investigated. Seventeen isolates from Norwegian hospitalized patients (ampicillin MIC 0.064‐>256 mg/L) with different C‐terminal pbp5 DNA sequences encoding 11 different amino acid sequences were analyzed with a 14 C‐radiolabeled penicillin‐ binding assay to PBP5 and with real‐time PCR quantification of pbp5 mRNA expression. Using multiple logistic regression analysis the amino acid substitution Met 485 was linked to ampicillin MIC and levels of 14 C‐radiolabeled penicillin bound to PBP5; however, there were isolates with identical PBP5 alleles and different ampicillin MICs. There was no relation between the quantity of pbp5 mRNA transcripts and ampicillin resistance. The results cannot explain ampicillin resistance in Norwegian clinical strains of E. faecium and indicate that other factors besides the properties of the C‐terminal part of PBP5 are most likely involved.