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Cafaro A, Stella M, Mesini A, Castagnola E, Cangemi G, Mattioli F, Baiardi G. Dose optimization and target attainment of vancomycin in children. Clin Biochem 2024; 125:110728. [PMID: 38325652 DOI: 10.1016/j.clinbiochem.2024.110728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/01/2024] [Accepted: 02/02/2024] [Indexed: 02/09/2024]
Abstract
Vancomycin is a glycopeptide antibiotic that has been adopted in clinical practice to treat gram-positive infections for more than 70 years. Despite vancomycin's long history of therapeutic use, optimal dose adjustments and pharmacokinetic/pharmacodynamic (PK/PD) target attainment in children are still under debate. Therapeutic drug monitoring (TDM) has been widely integrated into pediatric clinical practice to maximize efficacy and safety of vancomycin treatment. Area under the curve (AUC)-guided TDM has been recently recommended instead of trough-only TDM to ensure PK/PD target attainment of AUC0-24h/minimal inhibitory concentration (MIC) > 400 to 600 and minimize acute kidney injury risk. Bayesian forecasting in pediatric patients allows estimation of population PK to accurately predict individual vancomycin concentrations over time, and consequently total vancomycin exposure. AUC-guided TDM for vancomycin, preferably with Bayesian forecasting, is therefore suggested for all pediatric age groups and special pediatric populations. In this review we aim to analyze the current literature on the pediatric use of vancomycin and summarize the current knowledge on dosing optimization for target attainment in special patient populations.
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Affiliation(s)
- Alessia Cafaro
- Chromatography and Mass Spectrometry Section, Central Laboratory of Analysis, IRCCS Istituto Giannina, Gaslini, Genova, Italy
| | - Manuela Stella
- UOC Servizio di Sperimentazioni Cliniche Pediatriche, IRCCS Istituto Giannina Gaslini, Genova, Italy; Department of Internal Medicine, Pharmacology & Toxicology Unit, University of Genoa, Genova, Italy
| | - Alessio Mesini
- Infectious Disease Unit, Department of Pediatrics, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | - Elio Castagnola
- Infectious Disease Unit, Department of Pediatrics, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | - Giuliana Cangemi
- Chromatography and Mass Spectrometry Section, Central Laboratory of Analysis, IRCCS Istituto Giannina, Gaslini, Genova, Italy.
| | - Francesca Mattioli
- Department of Internal Medicine, Pharmacology & Toxicology Unit, University of Genoa, Genova, Italy; Clinical Pharmacology Unit, Ente Ospedaliero Ospedali Galliera, Genova, Italy
| | - Giammarco Baiardi
- Department of Internal Medicine, Pharmacology & Toxicology Unit, University of Genoa, Genova, Italy; Clinical Pharmacology Unit, Ente Ospedaliero Ospedali Galliera, Genova, Italy
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2
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Structure of VanS from vancomycin-resistant enterococci: A sensor kinase with weak ATP binding. J Biol Chem 2023; 299:103001. [PMID: 36764524 PMCID: PMC10017428 DOI: 10.1016/j.jbc.2023.103001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/28/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
The VanRS two-component system regulates the resistance phenotype of vancomycin-resistant enterococci. VanS is a sensor histidine kinase that responds to the presence of vancomycin by autophosphorylating and subsequently transferring the phosphoryl group to the response regulator, VanR. The phosphotransfer activates VanR as a transcription factor, which initiates the expression of resistance genes. Structural information about VanS proteins has remained elusive, hindering the molecular-level understanding of their function. Here, we present X-ray crystal structures for the catalytic and ATP-binding (CA) domains of two VanS proteins, derived from vancomycin-resistant enterococci types A and C. Both proteins adopt the canonical Bergerat fold that has been observed for CA domains of other prokaryotic histidine kinases. We attempted to determine structures for the nucleotide-bound forms of both proteins; however, despite repeated efforts, these forms could not be crystallized, prompting us to measure the proteins' binding affinities for ATP. Unexpectedly, both CA domains displayed low affinities for the nucleotide, with KD values in the low millimolar range. Since these KD values are comparable to intracellular ATP concentrations, this weak substrate binding could reflect a way of regulating expression of the resistance phenotype.
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3
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Li G, Walker MJ, De Oliveira DMP. Vancomycin Resistance in Enterococcus and Staphylococcus aureus. Microorganisms 2022; 11:microorganisms11010024. [PMID: 36677316 PMCID: PMC9866002 DOI: 10.3390/microorganisms11010024] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus are both common commensals and major opportunistic human pathogens. In recent decades, these bacteria have acquired broad resistance to several major classes of antibiotics, including commonly employed glycopeptides. Exemplified by resistance to vancomycin, glycopeptide resistance is mediated through intrinsic gene mutations, and/or transferrable van resistance gene cassette-carrying mobile genetic elements. Here, this review will discuss the epidemiology of vancomycin-resistant Enterococcus and S. aureus in healthcare, community, and agricultural settings, explore vancomycin resistance in the context of van and non-van mediated resistance development and provide insights into alternative therapeutic approaches aimed at treating drug-resistant Enterococcus and S. aureus infections.
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Guffey AA, Loll PJ. Regulation of Resistance in Vancomycin-Resistant Enterococci: The VanRS Two-Component System. Microorganisms 2021; 9:2026. [PMID: 34683347 PMCID: PMC8541618 DOI: 10.3390/microorganisms9102026] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 01/20/2023] Open
Abstract
Vancomycin-resistant enterococci (VRE) are a serious threat to human health, with few treatment options being available. New therapeutics are urgently needed to relieve the health and economic burdens presented by VRE. A potential target for new therapeutics is the VanRS two-component system, which regulates the expression of vancomycin resistance in VRE. VanS is a sensor histidine kinase that detects vancomycin and in turn activates VanR; VanR is a response regulator that, when activated, directs expression of vancomycin-resistance genes. This review of VanRS examines how the expression of vancomycin resistance is regulated, and provides an update on one of the field's most pressing questions: How does VanS sense vancomycin?
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Affiliation(s)
| | - Patrick J. Loll
- Department of Biochemistry & Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA;
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5
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Stogios PJ, Savchenko A. Molecular mechanisms of vancomycin resistance. Protein Sci 2020; 29:654-669. [PMID: 31899563 DOI: 10.1002/pro.3819] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/30/2019] [Accepted: 01/02/2020] [Indexed: 12/18/2022]
Abstract
Vancomycin and related glycopeptides are drugs of last resort for the treatment of severe infections caused by Gram-positive bacteria such as Enterococcus species, Staphylococcus aureus, and Clostridium difficile. Vancomycin was long considered immune to resistance due to its bactericidal activity based on binding to the bacterial cell envelope rather than to a protein target as is the case for most antibiotics. However, two types of complex resistance mechanisms, each comprised of a multi-enzyme pathway, emerged and are now widely disseminated in pathogenic species, thus threatening the clinical efficiency of vancomycin. Vancomycin forms an intricate network of hydrogen bonds with the d-Ala-d-Ala region of Lipid II, interfering with the peptidoglycan layer maturation process. Resistance to vancomycin involves degradation of this natural precursor and its replacement with d-Ala-d-lac or d-Ala-d-Ser alternatives to which vancomycin has low affinity. Through extensive research over 30 years after the initial discovery of vancomycin resistance, remarkable progress has been made in molecular understanding of the enzymatic cascades responsible. Progress has been driven by structural studies of the key components of the resistance mechanisms which provided important molecular understanding such as, for example, the ability of this cascade to discriminate between vancomycin sensitive and resistant peptidoglycan precursors. Important structural insights have been also made into the molecular evolution of vancomycin resistance enzymes. Altogether this molecular data can accelerate inhibitor discovery and optimization efforts to reverse vancomycin resistance. Here, we overview our current understanding of this complex resistance mechanism with a focus on the structural and molecular aspects.
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Affiliation(s)
- Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.,Center for Structural Genomics of Infectious Diseases (CSGID)
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.,Center for Structural Genomics of Infectious Diseases (CSGID).,Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
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Cho YS, Lee MH, Kim JM, Lee HS, Yoo HS, Park YH, Ryu PD. Immunological responses against vancomycin-resistant Enterococcus faecium and Enterococcus faecalis by mice. J Immunoassay Immunochem 2018; 39:163-172. [PMID: 29308974 DOI: 10.1080/15321819.2017.1407943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infections in humans can currently only be treated with vancomycin. Consequently, vancomycin-resistant Enterococcus spp. pose a serious public health hazard because MRSA can acquire their vancomycin resistance. While the microbiological and genetic characteristics of vancomycin-resistant enterococci (VRE) have been extensively studied, serological diagnostic tools for these organisms are lacking. The VanA and VanB classes of VRE show marked resistance. Here, we identified the VanA and VanB proteins that are immunogenic in mice. To do so, mice were orally infected with a VanA strain of E. faecium or a VanB strain of E. faecalis and the serologically immunogenic proteins were identified by SDS-PAGE and Western blot analysis. The mice reacted to the 27 and 65 kDa cell envelope (CE) proteins of VanA at 1 week post-infection (wpi) and then reacted to the 100 kDa cytoplasmic protein (CP) at 2-4 wpi. With regard to VanB, the mice responded at 1-4 wpi, 3-4 wpi, and 4 wpi to the 70 kDa, 25 and 35 kDa, and 79 kDa CE proteins, respectively, and at 3 wpi to the 39 kDa CP. The identification of these immunogenic proteins may be useful for diagnosing and for producing immunotherapeutic VRE antibodies.
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Affiliation(s)
- Yun Sang Cho
- a Bacterial Disease Division, Animal and Plant Disease Research Department , Animal and Plant Quarantine Agency , Gimcheon , Gyeongsangbuk-do , Republic of Korea
| | - Mun Han Lee
- b Laboratory of Veterinary Biochemistry, College of Veterinary Medicine , Seoul National University , Seoul , Republic of Korea
| | - Jong Man Kim
- a Bacterial Disease Division, Animal and Plant Disease Research Department , Animal and Plant Quarantine Agency , Gimcheon , Gyeongsangbuk-do , Republic of Korea
| | - Hee Soo Lee
- a Bacterial Disease Division, Animal and Plant Disease Research Department , Animal and Plant Quarantine Agency , Gimcheon , Gyeongsangbuk-do , Republic of Korea
| | - Han Sang Yoo
- c Laboratory of Veterinary Infectious Diseases, College of Veterinary Medicine , Seoul National University , Seoul , Republic of Korea
| | - Yong Ho Park
- d Laboratory of Veterinary Microbiology, College of Veterinary Medicine , Seoul National University , Seoul , Republic of Korea
| | - Pan Dong Ryu
- e Laboratory of Veterinary Pharmacology, College of Veterinary Medicine , Seoul National University , Seoul , Republic of Korea
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Laishram S, Sahni RD, Anandan S, Balaji V. Evaluation of the antimicrobial activity of daptomycin and linezolid against vancomycin-resistant Enterococcus spp. isolates in south India. J Glob Antimicrob Resist 2014; 2:194-197. [DOI: 10.1016/j.jgar.2014.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 02/26/2014] [Accepted: 03/12/2014] [Indexed: 11/25/2022] Open
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Vancomycin-resistant enterococci: Troublemaker of the 21st century. J Glob Antimicrob Resist 2014; 2:205-212. [PMID: 27873678 DOI: 10.1016/j.jgar.2014.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/03/2014] [Accepted: 04/09/2014] [Indexed: 11/22/2022] Open
Abstract
The emergence of multidrug-resistant and vancomycin-resistant enterococci during the last decade has made it difficult to treat nosocomial infections. Although various enterococcal species have been identified, only two (Enterococcus faecalis and Enterococcus faecium) are responsible for the majority of human infections. Vancomycin is an important therapeutic alternative against multidrug-resistant enterococci but is associated with a poor prognosis. Resistance to vancomycin dramatically reduces the therapeutic options for enterococcal infections. The bacterium develops resistance by modifying the C-terminal d-alanine of peptidoglycan to d-lactate, creating a d-Ala-d-Lac sequence that effectively reduces the affinity of vancomycin for the peptidoglycan by 1000-fold. Moreover, the resistance genes can be transferred from enterococci to Staphylococcus aureus, thereby posing a threat to patient safety and also a challenge for treating physicians. Judicious use of vancomycin and broad-spectrum antibiotics must be implemented, but strict infection control measures must also be followed to prevent nosocomial transmission of these organisms. Furthermore, improvements in clinical practice, rotation of antibiotics, herbal drugs, nanoantibiotics and the development of newer antibiotics based on a pharmacogenomic approach may prove helpful to overcome dreadful vancomycin-resistant enterococcal infections.
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Jang HC, Park WB, Kim HB, Kim EC, Oh MD. Clinical Features and Rate of Infective Endocarditis in Non-Faecalis and Non-faecium Enterococcal Bacteremia. Chonnam Med J 2011; 47:111-5. [PMID: 22111070 PMCID: PMC3214875 DOI: 10.4068/cmj.2011.47.2.111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 04/25/2011] [Indexed: 12/04/2022] Open
Abstract
Non-faecalis and non-faecium enterococci are an occasional cause of bacteremia, and some cases of infective endocarditis caused by these pathogens have been reported. However, the rate of infective endocarditis in non-faecalis and non-faecium enterococcal bacteremia is still undetermined. We compared the clinical features and the rate of infective endocarditis of 70 cases of non-faecalis and non-faecium enterococcal bacteremia with those of 65 cases of Enterococcus faecalis bacteremia. Non-faecalis and non-faecium enterococcal bacteremia was more frequently associated with biliary tract infection and polymicrobial bacteremia, and was less frequently associated with infective endocarditis, than was E. faecalis bacteremia (57% vs. 28%, p<0.01; 47% vs. 31%, p=0.05; 1% vs. 14%, p<0.01, respectively).
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Affiliation(s)
- Hee-Chang Jang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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10
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Detection of Antimicrobial Resistance Genes and Mutations Associated with Antimicrobial Resistance in Bacteria. Mol Microbiol 2011. [DOI: 10.1128/9781555816834.ch32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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Zárate MS, Gales A, Jordá-Vargas L, Yahni D, Relloso S, Bonvehi P, Monteiro J, Campos-Pignatari A, Smayevsky J. Contaminación ambiental durante un brote de enterococo resistente a vancomicina en un hospital de Argentina. Enferm Infecc Microbiol Clin 2007; 25:508-12. [PMID: 17915109 DOI: 10.1157/13109987] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Vancomycin-resistant enterococci isolates (VRE) have caused numerous outbreaks in intensive care units (ICUs). A contaminated hospital environment, the hands of health care workers (HCW), and carrier patients may play important roles in perpetuating the chain of transmission in these outbreaks. The aims of this study were to report the first VRE outbreak in our center and assess the role of environmental contamination and HCW hands in the spread of new cases of enterococcal infection. MATERIAL AND METHOD Between August and December 2003, surveillance cultures were performed with samples from all patients (n = 113) admitted to the ICU, as well as cultures of samples from the environment (n = 69) and HCW hands (n = 23). RESULTS Eighteen clinical samples from 8 patients and 7 environmental samples yielded Enterococcus faecium (24 strains) and E. avium (1 strain). VRE was not detected on HCW hands. All the VRE isolates belonged to a single clone and carried the vanA gene. CONCLUSION Environmental contamination provides an important reservoir for future outbreaks of VRE, perpetuating transmission of the microorganism in the hospital setting.
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Affiliation(s)
- Mariela Soledad Zárate
- Laboratorio de Bacteriología, Micología y Parasitología. Centro de Educación Médica e Investigaciones Clínicas Norberto Quirno (CEMIC). Capital Federal. Buenos Aires. Argentina.
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12
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Yang J, Lee D, Kim Y, Kang B, Kim K, Ha N. Occurrence of the van genes in Enterococcus faecalis and Enterococcus faecium from clinical isolates in Korea. Arch Pharm Res 2007; 30:329-36. [PMID: 17424939 DOI: 10.1007/bf02977614] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enterococcus faecalis and Enterococcus faecium isolated from Korea patients in 1998 and 2005 were tested for susceptibility to nine different antimicrobial agents, including vancomycin and teicoplanin. Polymerase chain reaction (PCR) was used for the detection of several vancomycin resistance genes such as vanA ('high level'), vanB ('moderate high level'), vanC1 and vanC2 ('low level'). Both E. faecalis and E. faecium exhibited a resistance of 80% and more than 60% to synercid and mupirocin, respectively. Moreover, an average of 76% of all isolates was resistant to ciprofloxacin, gentamicin, lincomycin, cefotaxime, and meropenem, confirming the multiple drug resistance of most of the isolates. No resistance to vancomycin or teicoplanin was observed in the 1998 E. faecalis and E. faecium isolates. However, the 2005 E. faecalis and E. faecium isolates exhibited resistance of 16% and 12% to vancomycin and teicoplanin, respectively. In addition, vanA gene was detected in 4 strains of 2005 E. faecium isolates, thus showing a high resistance to vancomycin. No other vancomycin resistance genes, including vanB, vanC1, and vanC2, were found in our isolates. In this study, we compared the occurrence of antimicrobial resistance and the presence of specific resistance genes in E. faecalis and E. faecium. The results showed that the 2005 isolates were usually more resistant than the 1998 isolates.
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Affiliation(s)
- Jaewook Yang
- School of Pharmacy, Western University, Pomona, California, USA
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13
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Abele-Horn M, Hommers L, Trabold R, Frosch M. Validation of VITEK 2 version 4.01 software for detection, identification, and classification of glycopeptide-resistant enterococci. J Clin Microbiol 2006; 44:71-6. [PMID: 16390951 PMCID: PMC1351969 DOI: 10.1128/jcm.44.1.71-76.2006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We evaluated the ability of the new VITEK 2 version 4.01 software to identify and detect glycopeptide-resistant enterococci compared to that of the reference broth microdilution method and to classify them into the vanA, vanB, vanC1, and vanC2 genotypes. Moreover, the accuracy of antimicrobial susceptibility testing with agents with improved potencies against glycopeptide-resistant enterococci was determined. A total of 121 enterococci were investigated. The new VITEK 2 software was able to identify 114 (94.2%) enterococcal strains correctly to the species level and to classify 119 (98.3%) enterococci correctly to the glycopeptide resistance genotype level. One Enterococcus casseliflavus strain and six Enterococcus faecium vanA strains with low-level resistance to vancomycin were identified with low discrimination, requiring additional tests. One of the vanA strains was misclassified as the vanB type, and one glycopeptide-susceptible E. facium wild type was misclassified as the vanA type. The overall essential agreements for antimicrobial susceptibility testing results were 94.2% for vancomycin, 95.9% for teicoplanin, 100% for quinupristin-dalfopristin and moxifloxacin, and 97.5% for linezolid. The rates of minor errors were 9% for teicoplanin and 5% for the other antibiotic agents. The identification and susceptibility data were produced within 4 h to 6 h 30 min and 8 h 15 min to 12 h 15 min. In conclusion, use of VITEK 2 version 4.01 software appears to be a reliable method for the identification and detection of glycopeptide-resistant enterococci as well as an improvement over the use of the former VITEK 2 database. However, a significant reduction in the detection time would be desirable.
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Maciá MD, Juan C, Oliver A, Hidalgo O, Pérez JL. Caracterización molecular de un brote por Enterococcus faecalis resistente a los glucopéptidos en una unidad de cuidados intensivos. Enferm Infecc Microbiol Clin 2005; 23:460-3. [PMID: 16185558 DOI: 10.1157/13078822] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Between January and August 2003 glycopeptide-resistant Enterococcus faecalis was isolated from eight patients admitted to the intensive care unit (ICU). METHODS Antibiotic susceptibility testing was performed by disk diffusion and the Etest, clonal relatedness of the isolates was studied by pulsed-field gel electrophoresis (PFGE), and the presence of vanA was investigated by PCR. RESULTS AND CONCLUSIONS All the isolates were vanA-positive and had an identical PFGE pattern, showing that an outbreak had occurred in our ICU.
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Affiliation(s)
- María Dolores Maciá
- Servicio de Microbiología, Hospital Universitario Son Dureta, Palma de Mallorca, Spain.
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15
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Panesso D, Abadía-Patiño L, Vanegas N, Reynolds PE, Courvalin P, Arias CA. Transcriptional analysis of the vanC cluster from Enterococcus gallinarum strains with constitutive and inducible vancomycin resistance. Antimicrob Agents Chemother 2005; 49:1060-6. [PMID: 15728903 PMCID: PMC549275 DOI: 10.1128/aac.49.3.1060-1066.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vanC glycopeptide resistance gene cluster encodes enzymes required for synthesis of peptidoglycan precursors ending in D-Ala-D-Ser. Enterococcus gallinarum BM4174 and SC1 are constitutively and inducibly resistant to vancomycin, respectively. Analysis of peptidoglycan precursors in both strains indicated that UDP-MurNAc-tetrapeptide and UDP-MurNAc-pentapeptide[D-Ser] were synthesized in E. gallinarum SC1 only in the presence of vancomycin (4 microg/ml), whereas the "resistance" precursors accumulated in the cytoplasm of BM4174 cells under both inducing and noninducing conditions. Northern hybridization and reverse transcription-PCR experiments revealed that all the genes from the cluster, vanC-1, vanXY(C), vanT, vanR(C), and vanS(C), were transcribed from a single promoter. In the inducible SC1 isolate, transcriptional regulation appeared to be responsible for inducible expression of resistance. Promoter mapping in E. gallinarum BM4174 revealed that the transcriptional start site was located 30 nucleotides upstream from vanC-1 and that the -10 promoter consensus sequence had high identity with that of the vanA cluster. Comparison of the deduced sequence of the vanS(C) genes from isolates with constitutive and inducible resistance revealed several amino acid substitutions located in the X box (R200L) and in the region between the F and G2 boxes (D312N, D312A, and G320S) of the putative sensor kinase proteins from isolates with constitutive resistance.
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Affiliation(s)
- Diana Panesso
- Bacterial Molecular Genetics Unit, Centro de Investigaciones, Universidad El Bosque, Bogotá, Columbia
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16
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Reynolds PE, Courvalin P. Vancomycin resistance in enterococci due to synthesis of precursors terminating in D-alanyl-D-serine. Antimicrob Agents Chemother 2005; 49:21-5. [PMID: 15616270 PMCID: PMC538887 DOI: 10.1128/aac.49.1.21-25.2005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Peter E Reynolds
- Department of Biochemistry, University of Cambridge, Tennis Court Rd., Cambridge CB2 1QW, United Kingdom.
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Choi SH, Lee SO, Kim TH, Chung JW, Choo EJ, Kwak YG, Kim MN, Kim YS, Woo JH, Ryu J, Kim NJ. Clinical features and outcomes of bacteremia caused by Enterococcus casseliflavus and Enterococcus gallinarum: analysis of 56 cases. Clin Infect Dis 2003; 38:53-61. [PMID: 14679448 DOI: 10.1086/380452] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2003] [Accepted: 08/21/2003] [Indexed: 11/03/2022] Open
Abstract
The clinical significance and virulence potential of Enterococcus casseliflavus/flavescens and Enterococcus gallinarum are still uncertain. We retrospectively analyzed 56 cases of significant bacteremia caused by E. casseliflavus or E. gallinarum. Of these cases, 25 (44.6%) were associated with polymicrobial bacteremia, and 43 (76.8%) were associated with entry via the biliary tract. Resistance to vancomycin was observed in 17 (30.4%) of these 56 patients, and this resistance was significantly associated with E. gallinarum bacteremia (adjusted odds ratio [AOR], 10.56; 95% confidence interval [CI], 2.41-46.27) and bacteremia without biliary tract origin (AOR, 6.74; 95% CI, 1.44-31.67). The crude mortality rate was 13%, and the bacteremia-related mortality rate was 1.9%. In conclusion, bacteremia due to E. casseliflavus and E. gallinarum is commonly associated with biliary tract disease and may be associated with a low risk of mortality.
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Affiliation(s)
- Sang-Ho Choi
- Division of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
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Boneca IG, Chiosis G. Vancomycin resistance: occurrence, mechanisms and strategies to combat it. Expert Opin Ther Targets 2003; 7:311-28. [PMID: 12783569 DOI: 10.1517/14728222.7.3.311] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Vancomycin has long been considered the antibiotic of last resort against serious and multi-drug-resistant infections caused by Gram-positive bacteria. However, vancomycin resistance has emerged, first in enterococci and, more recently, in Staphylococcus aureus. Here, the authors attempt to review the prevalence and the mechanisms of such resistance. Furthermore, they focus on strategies that have been developed or are under current investigation to overcome infections caused by vancomycin-resistant strains. Among these are glycopeptide derivatives with higher potency than vancomycin, small molecules that resensitise bacteria to the antibiotic and novel non-glycopeptide antibiotics. These agents are targeted to interfere with protein and/or peptidoglycan (PG) synthesis and integrity or with membrane permeability. Whilst most of these agents are still in clinical or preclinical development, some have entered the clinic and currently represent the only option for treating vancomycin-resistant enterococci (VRE).
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Affiliation(s)
- Ivo G Boneca
- Unité de Pathogénie Bactérienne des Muqueuses, Institut Pasteur, 25 - 28 Rue du Docteur Roux, 75724 Paris cedex 15, France.
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Dutta I, Reynolds PE. Biochemical and genetic characterization of the vanC-2 vancomycin resistance gene cluster of Enterococcus casseliflavus ATCC 25788. Antimicrob Agents Chemother 2002; 46:3125-32. [PMID: 12234834 PMCID: PMC128795 DOI: 10.1128/aac.46.10.3125-3132.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vanC-2 cluster of Enterococcus casseliflavus ATCC 25788 consisted of five genes (vanC-2, vanXY(C-2), vanT(C-2), vanR(C-2), and vanS(C-2)) and shared the same organization as the vanC cluster of E. gallinarum BM4174. The proteins encoded by these genes displayed a high degree of amino acid identity to the proteins encoded within the vanC gene cluster. The putative D,D-dipeptidase-D,D-carboxypeptidase, VanXY(C-2), exhibited 81% amino acid identity to VanXY(C), and VanT(C-2) displayed 65% amino acid identity to the serine racemase, VanT. VanR(C-2) and VanS(C-2) displayed high degrees of identity to VanR(C) and VanS(C), respectively, and contained the conserved residues identified as important to their function as a response regulator and histidine kinase, respectively. Resistance to vancomycin was expressed inducibly in E. casseliflavus ATCC 25788 and required an extended period of induction. Analysis of peptidoglycan precursors revealed that UDP-N-acetylmuramyl-L-Ala-delta-D-Glu-L-Lys-D-Ala-D-Ser could not be detected until several hours after the addition of vancomycin, and its appearance coincided with the resumption of growth. The introduction of additional copies of the vanT(C-2) gene, encoding a putative serine racemase, and the presence of supplementary D-serine in the growth medium both significantly reduced the period before growth resumed after addition of vancomycin. This suggested that the availability of D-serine plays an important role in the induction process.
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Affiliation(s)
- Ireena Dutta
- Department of Biochemistry, University of Cambridge, United Kingdom CB2 1QW
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Dargere S, Vergnaud M, Verdon R, Saloux E, Le Page O, Leclercq R, Bazin C. Enterococcus gallinarum endocarditis occurring on native heart valves. J Clin Microbiol 2002; 40:2308-10. [PMID: 12037119 PMCID: PMC130811 DOI: 10.1128/jcm.40.6.2308-2310.2002] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the first case of Enterococcus gallinarum endocarditis developing on normal native heart valves. Using phenotypic and molecular methods, a precise identification of this naturally vancomycin-resistant species allowed an optimal antibiotic therapy and the patient's recovery.
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Affiliation(s)
- Sylvie Dargere
- Service de Maladies Infectieuses, Cote de Nacre University Hospital, 14033 Caen, France.
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21
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Abstract
Glycopeptide antibiotics are integral components of the current antibiotic arsenal that is under strong pressures as a result of the emergence of a variety of resistance mechanisms over the past 15 years. Resistance has manifested itself largely through the expression of genes that encode proteins that reprogram cell wall biosynthesis and thus evade the action of the antibiotic in the enterococci, though recently new mechanisms have appeared that afford resistance and tolerance in the more virulent staphylococci and streptococci. Overcoming glycopeptide resistance will require innovative approaches to generate new antibiotics or otherwise to inhibit the action of resistance elements in various bacteria. The chemical complexity of the glycopeptides, the challenges of discovering and successfully exploiting new targets, and the growing number of distinct resistance types all increase the difficulty of the current problem we face as a result of the emergence of glycopeptide resistance.
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Affiliation(s)
- Jeff Pootoolal
- Antimicrobial Research Centre, Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada.
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22
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Kurup A, Tee WS, Loo LH, Lin R. Infection of central nervous system by motile Enterococcus: first case report. J Clin Microbiol 2001; 39:820-2. [PMID: 11158162 PMCID: PMC87831 DOI: 10.1128/jcm.39.2.820-822.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 66-year-old man with four indwelling ventriculoperitoneal shunts for multiloculated hydrocephalus from a complicated case of meningitis a year before developed shunt infection based on a syndrome of fever, drowsiness, and cerebrospinal fluid neutrophil pleocytosis in the background of repeated surgical manipulation to relieve successive shunt blockages. The cerebrospinal fluid culture, which yielded a motile Enterococcus species, was believed to originate from the gut. This isolate was lost in storage and could not be characterized further. The patient improved with vancomycin and high-dose ampicillin therapy. He relapsed a month later with Enterococcus gallinarum shunt infection, which responded to high-dose ampicillin and gentamicin therapy. This is probably the first case report of motile Enterococcus infection of the central nervous system.
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Affiliation(s)
- A Kurup
- Department of Internal Medicine, Singapore General Hospital, Singapore 169608.
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23
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Abstract
After they were first identified in the mid-1980s, vancomycin-resistant enterococci (VRE) spread rapidly and became a major problem in many institutions both in Europe and the United States. Since VRE have intrinsic resistance to most of the commonly used antibiotics and the ability to acquire resistance to most of the current available antibiotics, either by mutation or by receipt of foreign genetic material, they have a selective advantage over other microorganisms in the intestinal flora and pose a major therapeutic challenge. The possibility of transfer of vancomycin resistance genes to other gram-positive organisms raises significant concerns about the emergence of vancomycin-resistant Staphylococcus aureus. We review VRE, including their history, mechanisms of resistance, epidemiology, control measures, and treatment.
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Grohs P, Gutmann L, Legrand R, Schoot B, Mainardi JL. Vancomycin resistance is associated with serine-containing peptidoglycan in Enterococcus gallinarum. J Bacteriol 2000; 182:6228-32. [PMID: 11029446 PMCID: PMC94760 DOI: 10.1128/jb.182.21.6228-6232.2000] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Enterococcus gallinarum SC1, a low-level vancomycin-resistant strain, only monomeric muropentapeptides with a C-terminal D-alanine were detected after growth without vancomycin. In contrast, in SC1 induced by vancomycin, as well as in AIB39, a constitutive vancomycin-resistant strain, monomeric and dimeric muropentapeptides with a C-terminal D-serine were detected.
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Affiliation(s)
- P Grohs
- Laboratoire de Recherche Moléculaire sur les Antibiotiques, UFR Broussais-Hôtel Dieu, Université Paris VI, Paris, France
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25
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Abstract
After they were first identified in the mid-1980s, vancomycin-resistant enterococci (VRE) spread rapidly and became a major problem in many institutions both in Europe and the United States. Since VRE have intrinsic resistance to most of the commonly used antibiotics and the ability to acquire resistance to most of the current available antibiotics, either by mutation or by receipt of foreign genetic material, they have a selective advantage over other microorganisms in the intestinal flora and pose a major therapeutic challenge. The possibility of transfer of vancomycin resistance genes to other gram-positive organisms raises significant concerns about the emergence of vancomycin-resistant Staphylococcus aureus. We review VRE, including their history, mechanisms of resistance, epidemiology, control measures, and treatment.
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Affiliation(s)
- Y Cetinkaya
- Department of Healthcare Epidemiology and Division of Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0835, USA
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26
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Arias CA, Courvalin P, Reynolds PE. vanC cluster of vancomycin-resistant Enterococcus gallinarum BM4174. Antimicrob Agents Chemother 2000; 44:1660-6. [PMID: 10817725 PMCID: PMC89929 DOI: 10.1128/aac.44.6.1660-1666.2000] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycopeptide-resistant enterococci of the VanC type synthesize UDP-muramyl-pentapeptide[D-Ser] for cell wall assembly and prevent synthesis of peptidoglycan precursors ending in D-Ala. The vanC cluster of Enterococcus gallinarum BM4174 consists of five genes: vanC-1, vanXY(C), vanT, vanR(C), and vanS(C). Three genes are sufficient for resistance: vanC-1 encodes a ligase that synthesizes the dipeptide D-Ala-D-Ser for addition to UDP-MurNAc-tripeptide, vanXY(C) encodes a D,D-dipeptidase-carboxypeptidase that hydrolyzes D-Ala-D-Ala and removes D-Ala from UDP-MurNAc-pentapeptide[D-Ala], and vanT encodes a membrane-bound serine racemase that provides D-Ser for the synthetic pathway. The three genes are clustered: the start codons of vanXY(C) and vanT overlap the termination codons of vanC-1 and vanXY(C), respectively. Two genes which encode proteins with homology to the VanS-VanR two-component regulatory system were present downstream from the resistance genes. The predicted amino acid sequence of VanR(C) exhibited 50% identity to VanR and 33% identity to VanR(B). VanS(C) had 40% identity to VanS over a region of 308 amino acids and 24% identity to VanS(B) over a region of 285 amino acids. All residues with important functions in response regulators and histidine kinases were conserved in VanR(C) and VanS(C), respectively. Induction experiments based on the determination of D,D-carboxypeptidase activity in cytoplasmic extracts confirmed that the genes were expressed constitutively. Using a promoter-probing vector, regions upstream from the resistance and regulatory genes were identified that have promoter activity.
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Affiliation(s)
- C A Arias
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
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27
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Nelson RR. Intrinsically vancomycin-resistant gram-positive organisms: clinical relevance and implications for infection control. J Hosp Infect 1999; 42:275-82. [PMID: 10467540 DOI: 10.1053/jhin.1998.0605] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Intrinsic resistance to vancomycin in gram-positive bacteria presumably predates acquired vancomycin resistance in enterococci but it has only recently generated interest. Intrinsically resistant enterococci possessing the vanC gene and the non-enterococcal genera Leuconostoc, Lactobacillus, Pediococcus and Erysipelothrix are known to cause human infection. This review examines the available data on their identification, resistance mechanisms, epidemiology, clinical infections and antimicrobial susceptibility. Intrinsically vancomycin-resistant gram-positives are usually opportunistic pathogens. Although serious infections may occur, treatment options remain available. No additional infection control measures for the intrinsically resistant genera appear justified with currently available evidence, although vigilance should be maintained to detect future changes in susceptibility patterns.
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Affiliation(s)
- R R Nelson
- Department of Clinical Microbiology, Western Infirmary, Glasgow
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28
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Patel R, Rouse MS, Piper KE, Steckelberg JM. In vitro activity of linezolid against vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae. Diagn Microbiol Infect Dis 1999; 34:119-22. [PMID: 10354862 DOI: 10.1016/s0732-8893(99)00016-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We report the activity of the new oxazolidinone antimicrobial agent linezolid against 37 clinical isolates of vancomycin-resistant enterococci (including organisms carrying the vanA, vanB, vanC-1, and vanC-2/3 genes), 26 clinical isolates of methicillin-resistant S. aureus and 20 clinical isolates of high-level penicillin-resistant S. pneumoniae. All isolates of vancomycin-resistant enterococci were inhibited by < or = 4 ug/ml of linezolid. All isolates of methicillin-resistant S. aureus were inhibited by < or = 8 ug/ml of linezolid. All isolates of penicillin-resistant S. pneumoniae were inhibited by < or = 2 ug/ml of linezolid. Linezolid inhibits strains of multidrug resistant Gram-positive cocci in vitro at concentrations < or = 8 ug/ml.
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Affiliation(s)
- R Patel
- Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55902, USA
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29
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Ostrowsky B, Eliopoulos GM. Enterococcal Infections: Resistance Mechanisms, Treatment Strategies, and Hospital Issues. J Intensive Care Med 1999. [DOI: 10.1046/j.1525-1489.1999.00062.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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30
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Ostrowsky B, Eliopoulos GM. Analytic Reviews : Enterococcal Infections: Resistance Mechanisms, Treatment Strategies, and Hospital Issues. J Intensive Care Med 1999. [DOI: 10.1177/088506669901400202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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31
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Healy VL, Park IS, Walsh CT. Active-site mutants of the VanC2 D-alanyl-D-serine ligase, characteristic of one vancomycin-resistant bacterial phenotype, revert towards wild-type D-alanyl-D-alanine ligases. CHEMISTRY & BIOLOGY 1998; 5:197-207. [PMID: 9545431 DOI: 10.1016/s1074-5521(98)90633-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The rising number of vancomycin-resistant enterococci (VREs) is a major concern to modern medicine because vancomycin is currently the 'last resort' drug for life-threatening infections. The D-alanyl-D-X ligases (where X is an hydroxy or amino acid) of bacteria catalyze a critical step in bacterial cell-wall peptidoglycan assembly. In bacteria that produce glycopeptide antibiotics and in opportunistic pathogens, including VREs, D-, D-ligases serve as switches that confer antibiotic resistance on the bacteria themselves. Peptidoglycans in vancomycin-sensitive bacteria end in D-alanyl-D-alanine, whereas in vancomycin-resistant bacteria they end in D-alanyl-D-lactate or D-alanyl-D-serine. RESULTS We demonstrate that the selective utilization of D-serine by the Enterococcus casseliflavus VanC2 ligase can be altered by mutagenesis of one of two residues identified by homology to the X-ray structure of the Escherichia coli D-alanyl-Dalanine ligase (DdlB). The Arg322-->Met (R322M) and Phe250-->Tyr (F250Y) ligase mutants show a 36-44-fold decrease in the use of D-serine, as well as broadened specificity for utilization of other D-amino acids in place of D-serine. The F250Y R322M double mutant is effectively disabled as a D-alanyl-D-serine ligase and retains 10% of the catalytic activity of wild-type D-alanyl-D-alanine ligases, reflecting a 6,000-fold switch to the D-alanyl-D-alanine peptide. Correspondingly, the Leu282-->Arg mutant of the wild-type E. coli DdlB produced a 560-fold switch towards D-alanyl-D-serine formation. CONCLUSIONS Single-residue changes in the active-site regions of D-, D-ligases can cause substantial changes in recognition and activation of hydroxy or amino acids that have consequences for glycopeptide antibiotic efficacy. The observations reported here should provide an approach for combatting antibiotic-resistant bacteria.
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Affiliation(s)
- V L Healy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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32
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Patel R, Rouse MS, Piper KE, Cockerill FR, Steckelberg JM. In vitro activity of LY333328 against vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus, and penicillin-resistant Streptococcus pneumoniae. Diagn Microbiol Infect Dis 1998; 30:89-92. [PMID: 9554174 DOI: 10.1016/s0732-8893(97)00207-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report the activity of LY333328 against 35 clinical isolates of vancomycin-resistant enterococci (including organisms carrying the vanA, vanB, vanC-1, and vanC-2/3 genes, as determined by PCR), 33 clinical isolates of methicillin-resistant S. aureus, and 29 clinical isolates of high-level penicillin-resistant S. pneumoniae. All isolates of vancomycin-resistant enterococci were inhibited by 2 micrograms/mL LY333328, and 8 micrograms/mL LY333328 was bactericidal against all isolates tested. All isolates of methicillin-resistant S. aureus were inhibited by 1 microgram/mL LY333328, and 4 micrograms/mL LY333328 was bactericidal against all methicillin-resistant S. aureus isolates tested. All isolates of penicillin-resistant S. pneumoniae were inhibited by < 0.125 microgram/mL LY333328, and 0.25 microgram/mL LY333328 was bactericidal against all S. pneumoniae isolates tested. LY333328 is a promising new glycopeptide antimicrobial agent.
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Affiliation(s)
- R Patel
- Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55902, USA
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Patel R, Uhl JR, Kohner P, Hopkins MK, Steckelberg JM, Kline B, Cockerill FR. DNA sequence variation within vanA, vanB, vanC-1, and vanC-2/3 genes of clinical Enterococcus isolates. Antimicrob Agents Chemother 1998; 42:202-5. [PMID: 9449290 PMCID: PMC105485 DOI: 10.1128/aac.42.1.202] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We studied the DNA sequence variation of van genes of 34 isolates of Enterococcus spp. The isolates containing the vanB gene exhibited between 0 and 41 base pair changes per 801 bp studied when the vanB sequences were compared to that of the reference strain Enterococcus faecalis V583. The isolates carrying the vanC-2 gene exhibited between 0 and 23 base pair changes per 346 bp studied when the vanC-2 sequences were compared to that of the reference strain E. casseliflavus ATCC 25788. Little variation was noted in the vanA and vanC-1 genes.
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Affiliation(s)
- R Patel
- Division of Clinical Microbiology, Mayo Clinic and Foundation, Rochester, Minessota 55902, USA.
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34
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Abstract
Vancomycin-resistant enterococci have spread widely throughout the United States. Mechanisms of glycopeptide resistance are understood to a significant extent. These organisms are associated with considerable morbidity. Treatment options are limited, and control of their spread requires considerable effort and results in increased costs.
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Park IS, Lin CH, Walsh CT. Bacterial resistance to vancomycin: overproduction, purification, and characterization of VanC2 from Enterococcus casseliflavus as a D-Ala-D-Ser ligase. Proc Natl Acad Sci U S A 1997; 94:10040-4. [PMID: 9294159 PMCID: PMC23297 DOI: 10.1073/pnas.94.19.10040] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The VanC phenotype for clinical resistance of enterococci to vancomycin is exhibited by Enterococcus gallinarum and Enterococcus casseliflavus. Based on the detection of the cell precursor UDP-N-acetylmuramic acid pentapeptide intermediate terminating in D-Ala-D-Ser instead of D-Ala-D-Ala, it has been predicted that the VanC ligase would be a D-Ala-D-Ser rather than a D-Ala-D-Ala ligase. Overproduction of the E. casseliflavus ATCC 25788 vanC2 gene in Escherichia coli and its purification to homogeneity allowed demonstration of ATP-dependent D-Ala-D-Ser ligase activity. The kcat/Km2 (Km2 = Km for D-Ser or C-terminal D-Ala) ratio for D-Ala-D-Ser/D-Ala-D-Ala dipeptide formation is 270/0.69 for a 400-fold selection against D-Ala in the C-terminal position. VanC2 also has substantial D-Ala-D-Asn ligase activity (kcat/Km2 = 74 mM-1min-1).
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Affiliation(s)
- I S Park
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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36
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Sahm DF, Free L, Smith C, Eveland M, Mundy LM. Rapid characterization schemes for surveillance isolates of vancomycin-resistant enterococci. J Clin Microbiol 1997; 35:2026-30. [PMID: 9230375 PMCID: PMC229896 DOI: 10.1128/jcm.35.8.2026-2030.1997] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Surveillance cultures for vancomycin-resistant enterococci (VRE) and subsequent characterization of the isolates can be extremely burdensome and difficult. Therefore, efficient and reliable schemes for the characterization of surveillance isolates are needed. In this study, a commercial agar (bile esculin azide agar with 6 microg of vancomycin per ml [BEAA]; Remel, Lenexa, Kans.) was used in the initial screening step to establish relatively rapid (i.e., in < or = 24 h from the time of isolation) phenotype-based and PCR-based schemes for the detection and characterization of VRE. The phenotype-based scheme included Gram staining of growth on BEAA and subculture of cocci on sheep blood agar plates for vancomycin disk diffusion and pyrazinamidase (PYR) testing. For the PCR scheme, inocula for van gene detection were taken directly from the BEAA plates. The phenotypic approach was applied to 378 surveillance cultures that yielded growth on BEAA. Gram staining quickly eliminated gram-positive bacilli from further testing, and a negative PYR test classified 25 additional isolates as probable pediococci. A positive PYR test reliably identified 121 single-patient VRE isolates that included 83 Enterococcus faecium, 33 E. gallinarum, and 5 E. casseliflavus strains. The vancomycin inhibition zone size clearly distinguished VanA and VanB strains from VanC strains within 24 h of BEAA isolation. All VanA and VanB strains failed to produce zones of >6 mm, while only one VanC strain produced a zone of < 15 mm. Challenging this phenotypic scheme with 47 stock VRE isolates produced similar findings. In direct PCR analyses, false-negative vanA and vanB results occurred with 12% of the specimens. Many of the false-negative reactions also failed to produce an internal control product, which underscores the need for including control primers when a PCR scheme is used. In summary, the phenotype- and the PCR-based schemes provide efficient methods for characterizing VRE within 24 h of isolation.
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Affiliation(s)
- D F Sahm
- Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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37
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Abstract
Enterococci have been recognized as an important cause of nosocomial infections for almost 20 years and as a cause of endocarditis for almost a century. While long known for their capacity of displaying multiple antibiotic resistant traits, the extent to which this could occur was not fully appreciated until the emergence of enterococci with acquired resistance to vancomycin; this resistance has been particularly problematic because it often occurs in the uncommon subset of enterococci that are also highly resistant to ampicillin-a combination with devastating therapeutic consequences. The observation that vancomycin resistance can be transferred to and expressed in other gram-positive organisms, for which vancomycin is often considered the primary therapeutic alternative, is a chilling reminder of just how close we may be to a wide array of potentially untreatable "killer" microbes.
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Affiliation(s)
- B E Murray
- Department of Internal Medicine, University of Texas Medical School, Houston 77030, USA
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38
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Patel R, Uhl JR, Kohner P, Hopkins MK, Cockerill FR. Multiplex PCR detection of vanA, vanB, vanC-1, and vanC-2/3 genes in enterococci. J Clin Microbiol 1997; 35:703-7. [PMID: 9041416 PMCID: PMC229654 DOI: 10.1128/jcm.35.3.703-707.1997] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Vancomycin-resistant enterococci (VRE) are increasingly isolated from clinical specimens. One hundred clinical isolates of enterococci (E. casseliflavus/E. flavescens [n = 10], E. faecalis [n = 34], E. faecium [n = 43], E. avium [n = 1], E. gallinarum [n = 11], and E. raffinosus [n = 1]) were examined for the presence of vanA, vanB, vanC-1, and vanC-2/3 genes by a single multiplex PCR performed directly with colonies from blood agar plates. Six previously characterized VRE strains which carry either vanA, vanB, vanC-1, or vanC-2 genes were used as controls. To discriminate among van genes, the PCR amplicons were digested with MspI and were electrophoresed on agarose gels. Because of significant sequence homology between vanC-2 and vanC-3 genes, this assay is unable to discriminate these genes from each other; therefore, these are referred to as vanC-2/3 genes. PCR products were detected in 63 of the 100 clinical isolates. The restriction fragment length patterns were consistent with vanA for 10 strains, vanB for 30 strains, vanC-1 for 12 strains, vanC-2 for 6 strains, and vanA and vanC-1 for 1 strain. The vancomycin MICs for the isolates with restriction fragment length patterns consistent with vanA and vanB were all > and = 64 micrograms/ml. The vancomycin MICs for the isolates with restriction fragment length patterns consistent with vanC-1 or vanC-2 were 4 to 8 micrograms/ml. The vancomycin MICs for the isolates from which no PCR amplicons were produced were 2 to 4 micrograms/ml. A PCR product was produced in four isolates (vancomycin MICs, 4 to > 256 micrograms/ml) with restriction fragment length patterns differing from those for the control vanA, vanB, vanC-1, and vanC-2 isolates. DNA sequencing of these amplicons revealed that two of the four isolates had nucleic acid sequences which were closely related to the published sequence for the vanB gene and two had nucleic acid sequences which were closely related to the published sequence for the vanC-2 and vanC-3 genes. Multiplex PCR-restriction fragment length polymorphism appears to be a useful and convenient method for rapidly detecting and discriminating genotypes for vancomycin-resistant Enterococcus spp. in the clinical laboratory. In instances in which unusual restriction fragment patterns of PCR amplicons occur, DNA sequencing can be performed to discriminate van genotypes.
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Affiliation(s)
- R Patel
- Division of Clinical Microbiology, Mayo Clinic and Foundation, Rochester, Minnesota 55902, USA
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Ulijasz AT, Grenader A, Weisblum B. A vancomycin-inducible lacZ reporter system in Bacillus subtilis: induction by antibiotics that inhibit cell wall synthesis and by lysozyme. J Bacteriol 1996; 178:6305-9. [PMID: 8892834 PMCID: PMC178505 DOI: 10.1128/jb.178.21.6305-6309.1996] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have constructed a Bacillus subtilis strain in which expression of a vanH::lacZ gene fusion is regulated by VanR and VanS of Enterococcus faecium. This construct allows a nonpathogenic bacterial strain to be used as a model system for studying regulation of vancomycin resistance. Antibiotics and enzymes that affect cell wall biosynthesis and stability were tested for the ability to induce lacZ expression. As a result, fosfomycin and D-cycloserine were added to the group of peptidoglycan synthesis inhibitors shown to induce expression from the vanH promoter. Induction by cell wall hydrolytic enzymes, as well as by antibiotics whose actions may lead to the accumulation of chemically different peptidoglycan precursors, raises the possibility that models that postulate induction by peptidoglycan [correction of peptidodoglycan] precursors are wrong.
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Affiliation(s)
- A T Ulijasz
- Pharmacology Department, University of Wisconsin Medical School, Madison 53706, USA
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Jett B, Free L, Sahm DF. Factors influencing the vitek gram-positive susceptibility system's detection of vanB-encoded vancomycin resistance among enterococci. J Clin Microbiol 1996; 34:701-6. [PMID: 8904441 PMCID: PMC228873 DOI: 10.1128/jcm.34.3.701-706.1996] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Studies were conducted to identify factors contributing to the inability of the Vitek Gram-Positive Susceptibility system (GPS; bioMerieux, Vitek, Inc., Hazelwood, Mo.) to reliably detect vanB-mediated vancomycin resistance among enterococci. To some extent the accuracy of the GPS depended on a particular strain's level of resistance, as all isolates for which vancomycin MICs were > or = 128 mu g/ml were readily detected but detection of resistance expressed by several strains for which MICs were < or = 64 mu g/ml was sporadic. Factors besides the level of resistance were studied in two vanB strains. For one strain (Enterococcus faecium U8304), the ability of GPS to detect resistance was accurate and consistent, while for the other (Enterococcus faecalis V583), GPS results were inconsistent and unreliable. Using these isolates, we established that growth medium had the most notable effect on the detection of resistance. In the absence of vancomycin, Vitek GPS broth supported growth comparable to that obtained with brain heart infusion broth for both E. faecium U8304 and E. faecalis V583. However, in the presence of vancomycin the growth patterns changed dramatically so that neither VanB strain grew well in Vitek broth, and growth of V583 was barely detectable after 8 h of incubation. In contrast, good growth of both strains was observed in brain heart infusion broth supplemented with vancomycin. Additionally, the same medium effect was observed with other inducibly resistant VanB strains. In conclusion, although Vitek broth can support good enterococcal growth, this medium does not sufficiently support expression of vancomycin resistance by certain strains to allow them to be detected by the Vitek automated system. Furthermore, this observation establishes that the type of growth medium used can substantially influence the expression of vancomycin resistance and indicates that medium-based strategies should be explored for the enhancement of resistance detection among commercial systems.
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Affiliation(s)
- B Jett
- Department of Opthalmology, Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA
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Woodford N, Johnson AP, Morrison D, Speller DC. Current perspectives on glycopeptide resistance. Clin Microbiol Rev 1995; 8:585-615. [PMID: 8665471 PMCID: PMC172877 DOI: 10.1128/cmr.8.4.585] [Citation(s) in RCA: 215] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In the last 5 years, clinical isolates of gram-positive bacteria with intrinsic or acquired resistance to glycopeptide antibiotics have been encountered increasingly. In many of these isolates, resistance arises from an alteration of the antibiotic target site, with the terminal D-alanyl-D-alanine moiety of peptidoglycan precursors being replaced by groups that do not bind glycopeptides. Although the criteria for defining resistance have been revised frequently, the reliable detection of low-level glycopeptide resistance remains problematic and is influenced by the method chosen. Glycopeptide-resistant enterococci have emerged as a particular problem in hospitals, where in addition to sporadic cases, clusters of infections with evidence of interpatient spread have occurred. Studies using molecular typing methods have implicated colonization of patients, staff carriage, and environmental contamination in the dissemination of these bacteria. Choice of antimicrobial therapy for infections caused by glycopeptide-resistant bacteria may be complicated by resistance to other antibiotics. Severe therapeutic difficulties are being encountered among patients infected with enterococci, with some infections being untreatable with currently available antibiotics.
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Affiliation(s)
- N Woodford
- Antibiotic Reference Unit, Central Public Health Laboratory, London, England
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