Transition from resistance to hypersusceptibility to beta-lactam antibiotics associated with loss of a low-affinity penicillin-binding protein in a Streptococcus faecium mutant highly resistant to penicillin

Fontana, Roberta; Grossato, A.; Rossi, Lucía; Cheng, Y. R.; Satta, G.

doi:10.1128/aac.28.5.678

Cited by 95 publications

(69 citation statements)

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“…In strain Revl4, loss of PBP5 was associated with acquisition of hypersusceptibility to penicillin and ability to form filaments in the presence of the MIC but was not associated with the loss of any of the other peculiar characteristics and properties which were found to be associated with penicillin resistance in strain R40 (13). These observations can now be explained by the results described in this article.…”

Section: Resultssupporting

confidence: 72%

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Identification of a genetic element (psr) which negatively controls expression of Enterococcus hirae penicillin-binding protein 5

1993

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Enterococcus hirae ATCC 9790 produces a penicillin-binding protein (PBP5) of low penicillin affinity which under certain conditions can take over the functions of all the other PBPs. The 7.1-kb EcoRI fragment containing the pbp5 gene of this strain and of two mutants, of which one (E. hirae R40) overproduces PBP5 and the other (E. hirae Revl4) does not produce PBP5, was cloned in pUC18 and sequenced. In (4,7,12,23,30). These PBPs share several properties: they can be produced by the cells in large amounts, have similar molecular masses (about 75,000 Da), have an unusually low affinity for beta-lactam antibiotics, and play an important role in the mechanism of resistance to these antibiotics in enterococci and staphylococci.In enterococci, the low-affinity PBPs either are components of the normal PBP pattern or are generated by mutations in genes of the normal PBPs (1,12,21,32,33), whereas in staphylococci their synthesis is due to the acquisition of an additional gene (mec) which is practically identical in Staphylococcus aureus and several coagulase-negative species (22,27,29).In contrast to the evident and well-documented role of the low-affinity PBPs in the mechanism of resistance of grampositive cocci to beta-lactam antibiotics, very little is known about the role these proteins play in cell physiology. The most accepted hypothesis is that these proteins are multifunctional PBPs which are not essential for cell growth, at least under laboratory conditions, and can synthesize peptidoglycans under conditions which impair the activity of the other PBPs (4-6, 12, 13). Such an alternative system of peptidoglycan synthesis would represent an interesting and novel aspect of bacterial physiology.Previous studies of the low-affinity PBP of Enterococcus hirae ATCC 9790 (PBP5) based on mutants with a cell division defect and mutants with altered synthesis (either overproduction or lack) of PBP5 have elucidated certain aspects of the role of low-affinity PBPs in cell physiology (5, * Corresponding author. 6, 12, 13). Recently, the E. hirae PBP5-encoding gene (pbp5) has been cloned and sequenced (9), thus making possible investigations into the function of this PBP by a genetic approach.In this study, we sequenced the 7.1-kb EcoRI fragment, containing thepbp5 gene, cloned from chromosomal DNA of the wild-type E. hirae ATCC 9790, the PBP5 overproducer mutant E. hirae R40, and the PBP5 nonproducer mutant E. hirae Revl4. We found that the overproducer phenotype was associated with an 87-bp deletion in a genetic element, which we calledpsr (PBP5 synthesis repressor), located 1 kb upstream of the pbp5 gene, whereas the lack of PBP5 synthesis in E. hirae Revl4 was found to be caused by a nucleotide substitution in the coding frame of the protein which converted the 42nd codon, TCA, to the stop codon, TAA. MATERIALS AND METHODSBacterial strains and plasmids. The relevant properties of E. hirae strains and the recombinant plasmids constructed in this study are listed in Table 1. E. hirae strains were grown in brain heart infu...

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Section: Resultssupporting

confidence: 72%

“…6,12,13). Recently, the E. hirae PBP5-encoding gene (pbp5) has been cloned and sequenced (9), thus making possible investigations into the function of this PBP by a genetic approach.…”

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Identification of a genetic element (psr) which negatively controls expression of Enterococcus hirae penicillin-binding protein 5

1993

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“…Intrinsic resistance to ␤-lactams is maintained in enterococci through the overproduction of penicillin binding proteins (PBPs) with low binding affinity for ␤-lactams, most notably PBP 4 and PBP 5 (18)(19)(20)(21). The level of resistance differs between E. faecalis and E. faecium, with E. faecalis being 10-to 100-fold less susceptible to penicillin than streptococci and E. faecium being at least 4-to 16-fold less susceptible than E. faecalis (22).…”

Section: Antimicrobial Resistance Mechanisms and Approaches To Therapymentioning

confidence: 99%

Resistance Mechanisms, Epidemiology, and Approaches to Screening for Vancomycin-Resistant Enterococcus in the Health Care Setting

2016

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bInfections attributable to vancomycin-resistant Enterococcus (VRE) strains have become increasingly prevalent over the past decade. Prompt identification of colonized patients combined with effective multifaceted infection control practices can reduce the transmission of VRE and aid in the prevention of hospital-acquired infections (HAIs). Increasingly, the clinical microbiology laboratory is being asked to support infection control efforts through the early identification of potential patient or environmental reservoirs. This review discusses the factors that contribute to the rise of VRE as an important health care-associated pathogen, the utility of laboratory screening and various infection control strategies, and the available laboratory methods to identify VRE in clinical specimens. Hospital-acquired infections (HAIs) are a serious threat for patient care and carry a significant cost to hospitals, since treatment of these infections is no longer reimbursable. In addition, regulations requiring hospitals to report HAIs creates further pressure to reduce incidence rates. Screening patients at admission for methicillin-resistant Staphylococcus aureus (MRSA) has been a successful approach in reducing MRSA HAIs in some health care systems and may be a successful strategy for controlling other health care-associated pathogens, including Clostridium difficile, carbapenem-resistant Enterobacteriaceae (CRE), and vancomycin-resistant Enterococcus (VRE) (1). However, there is debate about the optimal approach to screening and infection control, which may differ between pathogens of interest.Members of the genus Enterococcus are well-documented pathogens associated with various clinical manifestations, including bacteremia, infective endocarditis, intra-abdominal and pelvic infections, urinary tract infections, and, in rare cases, central nervous system infections (2-4). Infection with vancomycin-resistant Enterococcus is associated with an increased mortality rate, illustrated by a 2.5-fold increase in mortality for patients suffering from VRE bacteremia (5). Vancomycin resistance in Enterococcus spp. has been increasing in prevalence since it was first encountered in 1986 (6, 7). Currently, 30% of Enterococcus species isolates from the United States are vancomycin resistant, and infection with these organisms causes an estimated 1,300 deaths each year (8). The majority of VRE are associated with the species E. faecium (77%) and E. faecalis (9%), with the remaining 14% of isolates representing species less frequently implicated in serious infections, including E. gallinarum, E. casseliflavus, E. avium, and E. raffinosus (8).The optimal approach to reducing VRE infections is multifactorial, requiring antimicrobial stewardship to reduce the selection of VRE in colonized patients, appropriate infection control practices to reduce transmission, and reliable sensitive laboratory methods for the detection of VRE in a timely manner. ANTIMICROBIAL RESISTANCE MECHANISMS AND APPROACHES TO THERAPYUnderstanding the mechanism be...

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“…16) but has a very low affinity for the ␤-lactam antibiotics (67,98 (210), and Ssc2 of Staphylococcus sciuri (247, 248) diverged in concert. They fall into a particular subclass, B1 (Fig.…”

Section: Class B Pen R Protein Fusions Of Gram-positive Bacteriamentioning

confidence: 99%

Biochemistry and Comparative Genomics of SxxK Superfamily Acyltransferases Offer a Clue to the Mycobacterial Paradox: Presence of Penicillin-Susceptible Target Proteins versus Lack of Efficiency of Penicillin as Therapeutic Agent

Goffin

Ghuysen

2002

Microbiol Mol Biol Rev

179

213

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The bacterial acyltransferases of the SxxK superfamily vary enormously in sequence and function, with conservation of particular amino acid groups and all-α and α/β folds. They occur as independent entities (free-standing polypeptides) and as modules linked to other polypeptides (protein fusions). They can be classified into three groups. The group I SxxK d,d-acyltransferases are ubiquitous in the bacterial world. They invariably bear the motifs SxxK, SxN(D), and KT(S)G. Anchored in the plasma membrane with the bulk of the polypeptide chain exposed on the outer face of it, they are implicated in the synthesis of wall peptidoglycans of the most frequently encountered (4→3) type. They are inactivated by penicillin and other β-lactam antibiotics acting as suicide carbonyl donors in the form of penicillin-binding proteins (PBPs). They are components of a morphogenetic apparatus which, as a whole, controls multiple parameters such as shape and size and allows the bacterial cells to enlarge and duplicate their particular pattern. Class A PBP fusions comprise a glycosyltransferase module fused to an SxxK acyltransferase of class A. Class B PBP fusions comprise a linker, i.e., protein recognition, module fused to an SxxK acyltransferase of class B. They ensure the remodeling of the (4→3) peptidoglycans in a cell cycle-dependent manner. The free-standing PBPs hydrolyze d,d peptide bonds. The group II SxxK acyltransferases frequently have a partially modified bar code, but the SxxK motif is invariant. They react with penicillin in various ways and illustrate the great plasticity of the catalytic centers. The secreted free-standing PBPs, the serine β-lactamases, and the penicillin sensors of several penicillin sensory transducers help the d,d-acyltransferases of group I escape penicillin action. The group III SxxK acyltransferases are indistinguishable from the PBP fusion proteins of group I in motifs and membrane topology, but they resist penicillin. They are referred to as Penr protein fusions. Plausible hypotheses are put forward on the roles that the Penr protein fusions, acting as l,d-acyltransferases, may play in the (3→3) peptidoglycan-synthesizing molecular machines. Shifting the wall peptidoglycan from the (4→3) type to the (3→3) type could help Mycobacterium tuberculosis and Mycobacterium leprae survive by making them penicillin resistant

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Transition from resistance to hypersusceptibility to beta-lactam antibiotics associated with loss of a low-affinity penicillin-binding protein in a Streptococcus faecium mutant highly resistant to penicillin

Cited by 95 publications

References 14 publications

Identification of a genetic element (psr) which negatively controls expression of Enterococcus hirae penicillin-binding protein 5

Identification of a genetic element (psr) which negatively controls expression of Enterococcus hirae penicillin-binding protein 5

Resistance Mechanisms, Epidemiology, and Approaches to Screening for Vancomycin-Resistant Enterococcus in the Health Care Setting

Biochemistry and Comparative Genomics of SxxK Superfamily Acyltransferases Offer a Clue to the Mycobacterial Paradox: Presence of Penicillin-Susceptible Target Proteins versus Lack of Efficiency of Penicillin as Therapeutic Agent

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