Differential Penicillin-Binding Protein 5 (PBP5) Levels in the Enterococcus faecium Clades with Different Levels of Ampicillin Resistance.
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.
Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center, Houston, Texas, USA.|Department of Microbiology and Molecular Genetics, The University of Texas Graduate School of Biomedical Sciences at Houston, The University of Texas Health Science Center, Houston, Texas, USA.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center, Houston, Texas, USA.
Maria Camila
0000-0001-9639-9690
MC
Montealegre
Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center, Houston, Texas, USA.|Department of Microbiology and Molecular Genetics, The University of Texas Graduate School of Biomedical Sciences at Houston, The University of Texas Health Science Center, Houston, Texas, USA.
Jung Hyeob
JH
Roh
Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center, Houston, Texas, USA.
Meredith
M
Rae
Department of BioSciences, Rice University, Houston, Texas, USA.
Milya G
MG
Davlieva
Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center, Houston, Texas, USA.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center, Houston, Texas, USA.
Kavindra V
KV
Singh
Department of BioSciences, Rice University, Houston, Texas, USA.
Yousif
Y
Shamoo
Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center, Houston, Texas, USA bem.asst@uth.tmc.edu.|Department of Microbiology and Molecular Genetics, The University of Texas Graduate School of Biomedical Sciences at Houston, The University of Texas Health Science Center, Houston, Texas, USA.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center, Houston, Texas, USA.
Barbara E
BE
Murray
D000667:Ampicillin / Q000494:pharmacology*; D000668:Ampicillin Resistance / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D016984:Enterococcus faecium / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D015964:Gene Expression Regulation, Bacterial; D014644:Genetic Variation; D005838:Genotype; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D046915:Penicillin-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; D012333:RNA, Messenger; D000667:Ampicillin
Enterococcus faecium; ampicillin; penicillin-binding protein 5; protein levels; resistance