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Evaluation of telavancin susceptibility in isolates of Staphylococcus aureus with reduced susceptibility to vancomycin. Eur J Clin Microbiol Infect Dis 2019; 38:2323-2330. [DOI: 10.1007/s10096-019-03683-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/15/2019] [Indexed: 10/26/2022]
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2
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Hassoun A, Linden PK, Friedman B. Incidence, prevalence, and management of MRSA bacteremia across patient populations-a review of recent developments in MRSA management and treatment. Crit Care 2017; 21:211. [PMID: 28807042 PMCID: PMC5557425 DOI: 10.1186/s13054-017-1801-3] [Citation(s) in RCA: 344] [Impact Index Per Article: 49.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection is still a major global healthcare problem. Of concern is S. aureus bacteremia, which exhibits high rates of morbidity and mortality and can cause metastatic or complicated infections such as infective endocarditis or sepsis. MRSA is responsible for most global S. aureus bacteremia cases, and compared with methicillin-sensitive S. aureus, MRSA infection is associated with poorer clinical outcomes. S. aureus virulence is affected by the unique combination of toxin and immune-modulatory gene products, which may differ by geographic location and healthcare- or community-associated acquisition. Management of S. aureus bacteremia involves timely identification of the infecting strain and source of infection, proper choice of antibiotic treatment, and robust prevention strategies. Resistance and nonsusceptibility to first-line antimicrobials combined with a lack of equally effective alternatives complicates MRSA bacteremia treatment. This review describes trends in epidemiology and factors that influence the incidence of MRSA bacteremia. Current and developing diagnostic tools, treatments, and prevention strategies are also discussed.
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Affiliation(s)
- Ali Hassoun
- Alabama Infectious Disease Center, 420 Lowell Drive, Suite 301, Huntsville, AL 35801 USA
| | - Peter K. Linden
- Allegheny General Hospital, Division of Surgical Critical Care, Allegheny Professional Building, 490 East North Ave, Suite 309, Pittsburgh, PA 15212 USA
| | - Bruce Friedman
- Joseph M. Still Burn Center, 3675 J. Dewey Gray Circle, Suite 200B, Augusta, GA 30909 USA
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Reproducible measurement of vancomycin MICs within the susceptible range in Staphylococcus aureus by a broth microdilution method with a "quasi-continuum" gradient of antibiotic concentrations. Eur J Clin Microbiol Infect Dis 2017; 36:2355-2360. [PMID: 28741096 DOI: 10.1007/s10096-017-3067-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/11/2017] [Indexed: 11/26/2022]
Abstract
The availability of reproducible broth microdilution (BMD) methods including inter log2 antibiotic dilutions for measuring Staphylococcus aureus (SA) vancomycin minimum inhibitory concentrations (MICs) within the susceptible range is needed to elucidate the impact of vancomycin MICs on clinical outcomes of invasive SA infections. Here, we report on the development of a very precise BMD method that incorporates the following incremental antibiotic concentrations: 0.50, 0.62, 0.75, 0.87, 1.0, 1.25, 1.40, 1.50, 1.60, 1.75, and 2.0 μg/mL. The intra- and inter-assay coefficients of variation of this method were around 20%. The mean of the differences in MIC values for all isolates obtained across two independent runs performed at one center was 0.04 μg/mL [95% confidence interval (CI), 0.011-0.07 μg/mL] and that for ten isolates measured at two different centers was 0.04 μg/mL (95% CI, 0-13 μg/mL). Vancomycin MIC values differed by less than 0.1 μg/mL between runs for most isolates. Storage of isolates at -20 °C for up to 3 months had no impact on the vancomycin MIC values. The mean vancomycin MIC values obtained by the Etest using a standard inoculum (0.5 McFarland) were significantly higher (p ≤ 0.001) than those measured by BMD and the MIC values measured by the two methods correlated poorly (Rho, 0.319; p = 0.148). Nevertheless, the mean MIC values measured by the Etest using lower inocula (107 or 106 CFU/mL) and those measured by BMD were comparable and correlated significantly (p = 0.004 for 107 CFU/mL and p = 0.029 for 106 CFU/mL).
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Kumarachandran G, Johnson JK, Shirley DA, Graffunder E, Heil EL. Predictors of Adverse Outcomes in Children With Staphylococcus aureus Bacteremia. J Pediatr Pharmacol Ther 2017. [PMID: 28638305 DOI: 10.5863/1551-6776-22.3.218] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Staphylococcus aureus bacteremia is a common infection, associated with significant morbidity and mortality in children. Factors associated with adverse treatment outcomes are poorly understood in the pediatric population. METHODS Our study compared clinical and microbiologic characteristics of children admitted during a 5-year period (2007-2012) to a large university-based hospital and found to have S aureus bacteremia with outcome measures, in order to identify risk factors associated with treatment failure (defined as 30-day mortality, delayed microbiologic resolution, or recurrence of S aureus bacteremia within 60 days of completing effective antibiotic therapy). RESULTS In all, 71 patients were found to have S aureus bacteremia, and of these, 17 patients (24%) experienced treatment failure. Based on the logistic regression model, only high vancomycin minimum inhibitory concentration in combination with a high-risk source of infection (i.e., infected graft or device, intra-abdominal infection, or respiratory tract infection) was significantly associated with risk of treatment failure. CONCLUSIONS Infection associated with a high-risk source may increase the chance of treatment failure in pediatric patients with S aureus bacteremia. Vancomycin minimum inhibitory concentration alone was not found to be a predictor of treatment outcomes.
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Impact of Vancomycin MIC on Treatment Outcomes in Invasive Staphylococcus aureus Infections. Antimicrob Agents Chemother 2017; 61:AAC.01845-16. [PMID: 27956430 DOI: 10.1128/aac.01845-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 12/08/2016] [Indexed: 01/09/2023] Open
Abstract
There are conflicting data on the association of vancomycin MIC (VAN-MIC) with treatment outcomes in Staphylococcus aureus infections. We investigated the relationship between high VAN-MIC and 30-day mortality and identified the risk factors for mortality in a large cohort of patients with invasive S. aureus (ISA) infections, defined as the isolation of S. aureus from a normally sterile site. Over a 2-year period, 1,027 adult patients with ISA infections were enrolled in 10 hospitals, including 673 (66%) patients with methicillin-resistant S. aureus (MRSA) infections. There were 200 (19.5%) isolates with high VAN-MIC (≥1.5 mg/liter) by Etest and 87 (8.5%) by broth microdilution (BMD). The all-cause 30-day mortality rate was 27.4%. High VAN-MIC by either method was not associated with all-cause 30-day mortality, and this finding was consistent across MIC methodologies and methicillin susceptibilities. We conclude that high VAN-MIC is not associated with increased risk of all-cause 30-day mortality in ISA infections. Our data support the view that VAN-MIC alone is not sufficient evidence to change current clinical practice.
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Pericàs JM, Messina JA, Garcia-de-la-Mària C, Park L, Sharma-Kuinkel BK, Marco F, Wray D, Kanafani ZA, Carugati M, Durante-Mangoni E, Tattevin P, Chu VH, Moreno A, Fowler VG, Miró JM. Influence of vancomycin minimum inhibitory concentration on the outcome of methicillin-susceptible Staphylococcus aureus left-sided infective endocarditis treated with antistaphylococcal β-lactam antibiotics: a prospective cohort study by the International Collaboration on Endocarditis. Clin Microbiol Infect 2017; 23:544-549. [PMID: 28159672 DOI: 10.1016/j.cmi.2017.01.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/19/2017] [Accepted: 01/22/2017] [Indexed: 01/16/2023]
Abstract
OBJECTIVES Left-sided methicillin-susceptible Staphylococcus aureus (MSSA) endocarditis treated with cloxacillin has a poorer prognosis when the vancomycin minimum inhibitory concentration (MIC) is ≥1.5 mg/L. We aimed to validate this using the International Collaboration on Endocarditis cohort and to analyse whether specific genetic characteristics were associated with a high vancomycin MIC (≥1.5 mg/L) phenotype. METHODS All patients with left-sided MSSA infective endocarditis treated with antistaphylococcal β-lactam antibiotics between 2000 and 2006 with available isolates were included. Vancomycin MIC was determined by Etest as either high (≥1.5 mg/L) or low (<1.5 mg/L). Isolates underwent spa typing to infer clonal complexes and multiplex PCR for identifying virulence genes. Univariate analysis was performed to evaluate the association between in-hospital and 1-year mortality, and vancomycin MIC phenotype. RESULTS Sixty-two cases met the inclusion criteria. Vancomycin MIC was low in 28 cases (45%) and high in 34 cases (55%). No significant differences in patient demographic data or characteristics of infection were observed between patients with infective endocarditis due to high and low vancomycin MIC isolates. Isolates with high and low vancomycin MIC had similar distributions of virulence genes and clonal lineages. In-hospital and 1-year mortality did not differ significantly between the two groups (32% (9/28) vs. 27% (9/34), p 0.780; and 43% (12/28) vs. 29% (10/34), p 0.298, for low and high vancomycin MIC respectively). CONCLUSIONS In this international cohort of patients with left-sided MSSA endocarditis treated with antistaphylococcal β-lactams, vancomycin MIC phenotype was not associated with patient demographics, clinical outcome or virulence gene repertoire.
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Affiliation(s)
- J M Pericàs
- Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - J A Messina
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Clinical Research Institute, Durham, NC, USA
| | - C Garcia-de-la-Mària
- Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - L Park
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Global Health Institute, Durham, NC, USA
| | - B K Sharma-Kuinkel
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA
| | - F Marco
- Department of Microbiology, Institute for Global Health, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain
| | - D Wray
- Infectious Disease Division, Medical University of South Carolina, Charleston, SC, USA
| | - Z A Kanafani
- Division of Infectious Diseases, American University of Beirut, Beirut, Lebanon
| | - M Carugati
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA
| | - E Durante-Mangoni
- Internal Medicine, Department of Clinical and Experimental Medicine, University of Campania 'Luigi Vanvitelli', Italy; Unit of Infectious and Transplant Medicine, 'V. Monaldi' Hospital, AORN dei Colli, Naples, Italy
| | - P Tattevin
- Infectious Diseases and Intensive Care Unit, Pontchaillou University Hospital, Rennes, France
| | - V H Chu
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Clinical Research Institute, Durham, NC, USA
| | - A Moreno
- Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - V G Fowler
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Clinical Research Institute, Durham, NC, USA
| | - J M Miró
- Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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Hos NJ, Jazmati N, Stefanik D, Hellmich M, AlSael H, Kern WV, Rieg S, Wisplinghoff H, Seifert H, Kaasch AJ. Determining vancomycin Etest MICs in patients with MRSA bloodstream infection does not support switching antimicrobials. J Infect 2016; 74:248-259. [PMID: 28017826 DOI: 10.1016/j.jinf.2016.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 12/16/2016] [Accepted: 12/18/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVES Elevated vancomycin minimum inhibitory concentrations (MIC) have been reported to adversely affect clinical outcome in methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI). We therefore examined the association between vancomycin MIC and outcome considering various potential confounders. METHODS Clinical data and bacterial isolates were prospectively collected from patients with MRSA BSI from 2006 to 2012 as part of the Invasive Staphylococcus aureus Infection Cohort (INSTINCT) study. Antimicrobial susceptibility was assessed by Etest, broth microdilution (BMD) and VITEK 2. Bacterial genotypes were determined by spa typing. Using univariate and Cox regression analyses, we investigated the impact of low (≤1.0 mg/L) and high (≥1.5 mg/L) vancomycin Etest MIC on clinical outcomes. RESULTS Ninety-one MRSA BSI episodes were included, of which 79 (86.8%) were caused by spa types t003, t032 and t045. High vancomycin MICs were seen only if using Etest but not confirmed using standard reference BMD. When episodes were stratified into low and high vancomycin Etest MIC groups, 30-day overall mortality was 34.5% and 27.3%, respectively (P = 0.64, OR 0.71; 95% confidence interval [CI] 0.27-1.79). Variables significantly associated with all-cause mortality in the Cox model were age (P = 0.003), acute physiology score (P = 0.0006), and Charlson comorbidity index (P = 0.018). CONCLUSIONS Vancomycin MICs may vary dependent on testing methodologies and local MRSA epidemiology. The patients' underlying disease and individual comorbidities rather than elevated vancomycin MICs determine adverse clinical outcomes in MRSA BSI. Routine Etest MIC testing of MRSA isolates is of limited value for treatment decisions.
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Affiliation(s)
- Nina J Hos
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany; Cologne Cluster of Excellence in Cellular Stress Responses in Aging-associated Diseases, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany; German Centre for Infection Research, Partner Site Bonn-Cologne, Germany
| | - Nathalie Jazmati
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany
| | - Danuta Stefanik
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany
| | - Martin Hellmich
- Institute of Medical Statistics, Informatics and Epidemiology, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Halil AlSael
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany
| | - Winfried V Kern
- Division of Infectious Diseases, Department of Medicine II, University Medical Center Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Siegbert Rieg
- Division of Infectious Diseases, Department of Medicine II, University Medical Center Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Hilmar Wisplinghoff
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany; German Centre for Infection Research, Partner Site Bonn-Cologne, Germany.
| | - Achim J Kaasch
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstr. 19-21, 50935 Cologne, Germany; Institute of Medical Microbiology and Hospital Hygiene, Heinrich-Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
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Purrello SM, Garau J, Giamarellos E, Mazzei T, Pea F, Soriano A, Stefani S. Methicillin-resistant Staphylococcus aureus infections: A review of the currently available treatment options. J Glob Antimicrob Resist 2016; 7:178-186. [PMID: 27889013 DOI: 10.1016/j.jgar.2016.07.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 07/03/2016] [Accepted: 07/16/2016] [Indexed: 12/16/2022] Open
Abstract
This review is the result of discussions that took place at the 5th MRSA Working Group Consensus Meeting and explores the possible treatment options available for different types of infections due to methicillin-resistant Staphylococcus aureus (MRSA), focusing on those antibiotics that could represent a valid alternative to vancomycin. In fact, whilst vancomycin remains a viable option, its therapy is moving towards individualised dosing. Other drugs, such as the new lipoglycopeptides (oritavancin, dalbavancin and telavancin) and fifth-generation cephalosporins (ceftaroline and ceftobiprole), are showing good in vitro potency and in vivo efficacy, especially for patients infected with micro-organisms with higher vancomycin minimum inhibitory concentrations (MICs). Tedizolid is an attractive agent for use both in hospital and community settings, but the post-marketing data will better clarify its potential. Daptomycin and linezolid have shown non-inferiority to vancomycin in the treatment of MRSA bacteraemia and non-inferiority/superiority to vancomycin in the treatment of hospital-acquired pneumonia. Thus, several options are available, but more data from clinical practice, especially for invasive infections, are needed to assign specific roles to each antibiotic and to definitely include them in the new antibacterial armamentarium.
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Affiliation(s)
- S M Purrello
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMAR Lab), Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - J Garau
- Department of Medicine, Hospital Universitari Mútua de Terrassa, Terrassa, Barcelona, Spain
| | - E Giamarellos
- 4th Department of Internal Medicine, Attikon University Hospital, Athens, Greece
| | - T Mazzei
- Department of Health Sciences, Clinical Pharmacology and Oncology Section, University of Firenze, Firenze, Italy
| | - F Pea
- Institute of Clinical Pharmacology, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Udine, Italy; Department of Experimental and Clinical Medical Sciences, University of Udine, Udine, Italy
| | - A Soriano
- Department of Infectious Diseases, IDIBAPS, Hospital Clínic of Barcelona, Barcelona, Spain
| | - S Stefani
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMAR Lab), Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.
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Impact of Time to Appropriate Therapy on Mortality in Patients with Vancomycin-Intermediate Staphylococcus aureus Infection. Antimicrob Agents Chemother 2016; 60:5546-53. [PMID: 27401565 DOI: 10.1128/aac.00925-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 07/01/2016] [Indexed: 12/29/2022] Open
Abstract
Despite the increasing incidence of vancomycin-intermediate Staphylococcus aureus (VISA) infections, few studies have examined the impact of delay in receipt of appropriate antimicrobial therapy on outcomes in VISA patients. We examined the effects of timing of appropriate antimicrobial therapy in a cohort of patients with sterile-site methicillin-resistant S. aureus (MRSA) and VISA infections. In this single-center, retrospective cohort study, we identified all patients with MRSA or VISA sterile-site infections from June 2009 to February 2015. Clinical outcomes were compared according to MRSA/VISA classification, demographics, comorbidities, and antimicrobial treatment. Thirty-day all-cause mortality was modeled with Kaplan-Meier curves. Multivariate logistic regression analysis (MVLRA) was used to determine odds ratios for mortality. We identified 354 patients with MRSA (n = 267) or VISA (n = 87) sterile-site infection. Fifty-five patients (15.5%) were nonsurvivors. Factors associated with mortality in MVLRA included pneumonia, unknown source of infection, acute physiology and chronic health evaluation (APACHE) II score, solid-organ malignancy, and admission from skilled care facilities. Time to appropriate antimicrobial therapy was not significantly associated with outcome. Presence of a VISA infection compared to that of a non-VISA S. aureus infection did not result in excess mortality. Linezolid use was a risk for mortality in patients with APACHE II scores of ≥14. Our results suggest that empirical vancomycin use in patients with VISA infections does not result in excess mortality. Future studies should (i) include larger numbers of patients with VISA infections to confirm the findings presented here and (ii) determine the optimal antibiotic therapy for critically ill patients with MRSA and VISA infections.
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Yoon YK, Park DW, Sohn JW, Kim HY, Kim YS, Lee CS, Lee MS, Ryu SY, Jang HC, Choi YJ, Kang CI, Choi HJ, Lee SS, Kim SW, Kim SI, Kim ES, Kim JY, Yang KS, Peck KR, Kim MJ. Effects of inappropriate empirical antibiotic therapy on mortality in patients with healthcare-associated methicillin-resistant Staphylococcus aureus bacteremia: a propensity-matched analysis. BMC Infect Dis 2016; 16:331. [PMID: 27418274 PMCID: PMC4946186 DOI: 10.1186/s12879-016-1650-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 06/08/2016] [Indexed: 11/19/2022] Open
Abstract
Background The purported value of empirical therapy to cover methicillin-resistant Staphylococcus aureus (MRSA) has been debated for decades. The purpose of this study was to evaluate the effects of inappropriate empirical antibiotic therapy on clinical outcomes in patients with healthcare-associated MRSA bacteremia (HA-MRSAB). Methods A prospective, multicenter, observational study was conducted in 15 teaching hospitals in the Republic of Korea from February 2010 to July 2011. The study subjects included adult patients with HA-MRSAB. Covariate adjustment using the propensity score was performed to control for bias in treatment assignment. The predictors of in-hospital mortality were determined by multivariate logistic regression analyses. Results In total, 345 patients with HA-MRSAB were analyzed. The overall in-hospital mortality rate was 33.0 %. Appropriate empirical antibiotic therapy was given to 154 (44.6 %) patients. The vancomycin minimum inhibitory concentrations of the MRSA isolates ranged from 0.5 to 2 mg/L by E-test. There was no significant difference in mortality between propensity-matched patient pairs receiving inappropriate or appropriate empirical antibiotics (odds ratio [OR] = 1.20; 95 % confidence interval [CI] = 0.71–2.03). Among patients with severe sepsis or septic shock, there was no significant difference in mortality between the treatment groups. In multivariate analyses, severe sepsis or septic shock (OR = 5.45; 95 % CI = 2.14–13.87), Charlson’s comorbidity index (per 1-point increment; OR = 1.52; 95 % CI = 1.27–1.83), and prior receipt of glycopeptides (OR = 3.24; 95 % CI = 1.08–9.67) were independent risk factors for mortality. Conclusion Inappropriate empirical antibiotic therapy was not associated with clinical outcome in patients with HA-MRSAB. Prudent use of empirical glycopeptide therapy should be justified even in hospitals with high MRSA prevalence.
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Affiliation(s)
- Young Kyung Yoon
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Dae Won Park
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Jang Wook Sohn
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Hyo Youl Kim
- Department of Internal Medicine, Yonsei University Wonju College of Medicine, Won Ju, Republic of Korea
| | - Yeon-Sook Kim
- Department of Internal Medicine, Chungnam National University Hospital, Daejon, Republic of Korea
| | - Chang-Seop Lee
- Department of Internal Medicine, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Mi Suk Lee
- Department of Internal Medicine, Kyung Hee University School of Medicine, Seoul, Republic of Korea
| | - Seong-Yeol Ryu
- Department of Internal Medicine, Keimyung University Dongsan Hospital, Daegu, Republic of Korea
| | - Hee-Chang Jang
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Young Ju Choi
- Department of Internal Medicine, National Cancer Center, Seoul, Republic of Korea
| | - Cheol-In Kang
- Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hee Jung Choi
- Department of Internal Medicine, Ewha Women's University School of Medicine, Seoul, Republic of Korea
| | - Seung Soon Lee
- Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea
| | - Shin Woo Kim
- Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Republic of Korea
| | - Sang Il Kim
- Department of Internal Medicine, Catholic University of Korea, College of Medicine, Seoul, Republic of Korea
| | - Eu Suk Kim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul, Republic of Korea
| | - Jeong Yeon Kim
- Department of Internal Medicine, Samyook Medical Center, Seoul, Republic of Korea
| | - Kyung Sook Yang
- Department of Biostatistics, Korea University College of Medicine, Seoul, Republic of Korea
| | - Kyong Ran Peck
- Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Min Ja Kim
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
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Falcón R, Martínez A, Albert E, Madrid S, Oltra R, Giménez E, Soriano M, Vinuesa V, Gozalbo D, Gil ML, Navarro D. High vancomycin MICs within the susceptible range in Staphylococcus aureus bacteraemia isolates are associated with increased cell wall thickness and reduced intracellular killing by human phagocytes. Int J Antimicrob Agents 2016; 47:343-50. [PMID: 27056298 DOI: 10.1016/j.ijantimicag.2016.01.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/25/2016] [Accepted: 01/29/2016] [Indexed: 12/22/2022]
Abstract
Vancomycin minimum inhibitory concentrations (MICs) at the upper end of the susceptible range for Staphylococcus aureus have been associated with poor clinical outcomes of bloodstream infections. We tested the hypothesis that high vancomycin MICs in S. aureus bacteraemia isolates are associated with increased cell wall thickness and suboptimal bacterial internalisation or lysis by human phagocytes. In total, 95 isolates were evaluated. Original vancomycin MICs were determined by Etest. The susceptibility of S. aureus isolates to killing by phagocytes was assessed in a human whole blood assay. Internalisation of bacterial cells by phagocytes was investigated by flow cytometry. Cell wall thickness was evaluated by transmission electron microscopy. Genotypic analysis of S. aureus isolates was performed using a DNA microarray system. Vancomycin MICs were significantly higher (P=0.006) in isolates that were killed suboptimally (killing index <60%) compared with those killed efficiently (killing index >70%) and tended to correlate inversely (P=0.08) with the killing indices. Isolates in both killing groups were internalised by human neutrophils and monocytes with comparable efficiency. The cell wall was significantly thicker (P=0.03) in isolates in the low killing group. No genotypic differences were found between the isolates in both killing groups. In summary, high vancomycin MICs in S. aureus bacteraemia isolates were associated with increased cell wall thickness and reduced intracellular killing by phagocytes.
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Affiliation(s)
- Rocío Falcón
- Microbiology Service, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain
| | - Alba Martínez
- Department of Microbiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
| | - Eliseo Albert
- Microbiology Service, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain
| | - Silvia Madrid
- Microbiology Service, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain
| | - Rosa Oltra
- Unit of Infectious Diseases, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain
| | - Estela Giménez
- Microbiology Service, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain
| | - Mario Soriano
- Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Víctor Vinuesa
- Microbiology Service, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain
| | - Daniel Gozalbo
- Department of Microbiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
| | - María Luisa Gil
- Department of Microbiology, Faculty of Biological Sciences, University of Valencia, Valencia, Spain
| | - David Navarro
- Microbiology Service, Hospital Clínico Universitario de Valencia, Fundación INCLIVA, Valencia, Spain; Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain.
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McLain JE, Cytryn E, Durso LM, Young S. Culture-based Methods for Detection of Antibiotic Resistance in Agroecosystems: Advantages, Challenges, and Gaps in Knowledge. JOURNAL OF ENVIRONMENTAL QUALITY 2016; 45:432-40. [PMID: 27065389 DOI: 10.2134/jeq2015.06.0317] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Various culture-based methodologies are used in assessment of antibiotic resistance in samples collected in agroecosystems. Culture-based methods commonly involve isolating target bacteria on general or selective media and assessing growth in response to specific concentrations of antibiotics. The advantages of culture-based methods are multifold. In particular, isolation of bacteria is key to understanding phenotypic characteristics of isolates and their resistance patterns, and most national and international antibiotic resistance monitoring projects are isolate based. This review covers current knowledge of bacterial groups and antibiotics commonly targeted in resistance studies using bacterial culture and discusses the range in methods used, data interpretation, and factors supporting and confounding the use of culture-based methods in assessment of antibiotic resistance. Gaps in knowledge related to study design and resistance databases are discussed. Finally, a case is made for the integration of culture-based and molecular methods to better inform our understanding of antibiotic resistance in agroecosystems.
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Cuervo G, Gasch O, Shaw E, Camoez M, Domínguez MÁ, Padilla B, Pintado V, Almirante B, Lepe JA, López-Medrano F, Ruiz de Gopegui E, Martínez JA, Montejo JM, Perez-Nadales E, Arnáiz A, Goenaga MÁ, Benito N, Horcajada JP, Rodríguez-Baño J, Pujol M. Clinical characteristics, treatment and outcomes of MRSA bacteraemia in the elderly. J Infect 2016; 72:309-16. [PMID: 26723914 DOI: 10.1016/j.jinf.2015.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/13/2015] [Accepted: 12/16/2015] [Indexed: 02/05/2023]
Abstract
OBJECTIVES To compare clinical and microbiological characteristics, treatment and outcomes of MRSA bacteraemia among elderly and younger patients. MATERIAL AND METHODS Prospective study conducted at 21 Spanish hospitals including patients with MRSA bacteraemia diagnosed between June/2008 and December/2009. Episodes diagnosed in patients aged 75 or more years old (≥75) were compared with the rest of them (<75). RESULTS Out of 579 episodes of MRSA bacteraemia, 231 (39.9%) occurred in patients ≥75. Comorbidity was significantly higher in older patients (Charlson score ≥4: 52.8 vs. 44%; p = .037) as was the severity of the underlying disease (McCabe ≥1: 61.9 vs. 43.4%; p < .001). In this group the acquisition was more frequently health-care related (43.3 vs. 33.9%, p = .023), mostly from long-term care centers (12.1 vs. 3.7%, p < .001). An unknown focus was more frequent among ≥75 (19.9 vs. 13.8%; p = .050) while severity at presentation was similar between groups (Pitt score ≥3: 31.2 vs. 27.6%; p = .352). The prevalence of vancomycin resistant isolates was similar between groups, as was the appropriateness of empirical antibiotic therapy. Early (EM) and overall mortality (OM) were significantly more frequent in the ≥75 group (EM: 12.1 vs. 6%; p = .010 OM: 42.9 vs. 23%; p < .001). In multivariate analysis age ≥75 was an independent risk factor for overall mortality (aOR: 2.47, CI: 1.63-3.74; p < .001). CONCLUSION MRSA bacteraemia was frequent in patients aged ≥75 of our cohort. This group had higher comorbidity rates and the source of infection was more likely to be unknown. Although no differences were seen in severity or adequacy of empiric therapy, elderly patients showed a higher overall mortality.
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Affiliation(s)
- Guillermo Cuervo
- Department of Infectious Diseases, H. Bellvitge, Barcelona, Spain.
| | - Oriol Gasch
- Department of Infectious Diseases, H. Parc Taulí, Sabadell, Spain.
| | - Evelyn Shaw
- Department of Infectious Diseases, H. Bellvitge, Barcelona, Spain.
| | - Mariana Camoez
- Department of Microbiology, H. Bellvitge, Barcelona, Spain.
| | | | - Belén Padilla
- Department of Infectious Diseases, H. Gregorio Marañón, Madrid, Spain.
| | - Vicente Pintado
- Department of Infectious Diseases, H. Ramón y Cajal, Madrid, Spain.
| | - Benito Almirante
- Department of Infectious Diseases, H. Vall d'Hebrón, Barcelona, Spain.
| | - José A Lepe
- Department of Infectious Diseases, H. Virgen del Rocío, Sevilla, Spain.
| | | | | | - José A Martínez
- Department of Infectious Diseases, H. Clìnic, Barcelona, Spain.
| | | | - Elena Perez-Nadales
- Department of Infectious Diseases, H. Reina Sofía/IMIBIC/UCO, Córdoba, Spain.
| | - Ana Arnáiz
- Department of Microbiology, H. Marqués de Valdecilla, Santander, Spain.
| | | | - Natividad Benito
- Department of Infectious Diseases, H. de la Santa Creu i Sant Pau, Barcelona, Spain.
| | | | | | - Miquel Pujol
- Department of Infectious Diseases, H. Bellvitge, Barcelona, Spain.
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Susceptibility trends including emergence of linezolid resistance among coagulase-negative staphylococci and meticillin-resistant Staphylococcus aureus from invasive infections. Int J Antimicrob Agents 2015; 46:622-30. [DOI: 10.1016/j.ijantimicag.2015.07.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/20/2015] [Accepted: 07/22/2015] [Indexed: 12/20/2022]
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Cuervo G, Camoez M, Shaw E, Dominguez MÁ, Gasch O, Padilla B, Pintado V, Almirante B, Molina J, López-Medrano F, Ruiz de Gopegui E, Martinez JA, Bereciartua E, Rodriguez-Lopez F, Fernandez-Mazarrasa C, Goenaga MÁ, Benito N, Rodriguez-Baño J, Espejo E, Pujol M. Methicillin-resistant Staphylococcus aureus (MRSA) catheter-related bacteraemia in haemodialysis patients. BMC Infect Dis 2015; 15:484. [PMID: 26518487 PMCID: PMC4628295 DOI: 10.1186/s12879-015-1227-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 10/19/2015] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The aim of the study was to determine clinical and microbiological differences between patients with methicillin-resistant Staphylococcus aureus (MRSA) catheter-related bacteraemia (CRB) undergoing or not undergoing haemodialysis, and to compare outcomes. METHODS Prospective multicentre study conducted at 21 Spanish hospitals of patients with MRSA bacteraemia diagnosed between June 2008 and December 2009. Patients with MRSA-CRB were selected. Data of patients on haemodialysis (HD-CRB) and those not on haemodialysis (non-HD-CRB) were compared. RESULTS Among 579 episodes of MRSA bacteraemia, 218 (37.7%) were CRB. Thirty-four (15.6%) were HD-CRB and 184 (84.4%) non-HD-CRB. All HD-CRB patients acquired the infection at dialysis centres, while in 85.3% of the non-HD-CRB group the infection was nosocomial (p < .001). There were no differences in age, gender or severity of bacteraemia (Pitt score); comorbidities (Charlson score ≥ 4) were higher in the HD-CRB group than in the non-HD-CRB group (73.5% vs. 46.2%, p = .003). Although there were no differences in VAN-MIC ≥ 1.5 mg/L according to microdilution, using the E-test a higher rate of VAN-MIC ≥ 1.5 mg/L was observed in HD-CRB than in non-HD-CRB patients (63.3% vs. 44.1%, p = .051). Vancomycin was more frequently administered in the HD-CRB group than in the non-HD-CRB group (82.3% vs. 42.4%, p = <.001) and therefore the appropriate empirical therapy was significantly higher in HD-CRB group (91.2% vs. 73.9%, p = .029). There were no differences with regard to catheter removal (79.4% vs. 84.2%, p = .555, respectively). No significant differences in mortality rate were observed between both groups (Overall mortality: 11.8% vs. 27.2%, p = .081, respectively), but there was a trend towards a higher recurrence rate in HD-CRB group (8.8% vs. 2.2%, p = .076). CONCLUSIONS In our multicentre study, ambulatory patients in chronic haemodialysis represented a significant proportion of cases of MRSA catheter-related bacteraemia. Although haemodialysis patients with MRSA catheter-related bacteraemia had significantly more comorbidities and higher proportion of strains with reduced vancomycin susceptibility than non-haemodialysis patients, overall mortality between both groups was similar.
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Affiliation(s)
- Guillermo Cuervo
- Department of Infectious Diseases, Hospital Universitari de Bellvitge; Feixa Llarga s/n, 08907, L'Hospitalet de Llobregat, Barcelona, Spain.
| | - Mariana Camoez
- Department of Microbiology, H. Bellvitge, Barcelona, Spain.
| | - Evelyn Shaw
- Department of Infectious Diseases, Hospital Universitari de Bellvitge; Feixa Llarga s/n, 08907, L'Hospitalet de Llobregat, Barcelona, Spain.
| | | | - Oriol Gasch
- Department of Infectious Diseases, H. Parc Taulí, Sabadell, Spain.
| | - Belén Padilla
- Department of Infectious Diseases, H. Gregorio Marañón, Madrid, Spain.
| | - Vicente Pintado
- Department of Infectious Diseases, H. Ramón y Cajal, Madrid, Spain.
| | - Benito Almirante
- Department of Infectious Diseases, H. Vall d'Hebrón, Barcelona, Spain.
| | - José Molina
- Department of Infectious Diseases, H. Virgen del Rocío, Sevilla, Spain.
| | | | | | - José A Martinez
- Department of Infectious Diseases, H. Clìnic, Barcelona, Spain.
| | | | | | | | | | - Natividad Benito
- Department of Infectious Diseases, H. de la Santa Creu i Sant Pau, Barcelona, Spain.
| | | | - Elena Espejo
- Department of Infectious Diseases, H. Terrassa, Terrassa, Spain.
| | - Miquel Pujol
- Department of Infectious Diseases, Hospital Universitari de Bellvitge; Feixa Llarga s/n, 08907, L'Hospitalet de Llobregat, Barcelona, Spain.
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Impact of area under the concentration-time curve to minimum inhibitory concentration ratio on vancomycin treatment outcomes in methicillin-resistant Staphylococcus aureus bacteraemia. Int J Antimicrob Agents 2015; 46:689-95. [PMID: 26555059 DOI: 10.1016/j.ijantimicag.2015.09.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/15/2015] [Accepted: 09/18/2015] [Indexed: 12/20/2022]
Abstract
There have been few clinical studies on the association between the vancomycin 24-h area under the concentration-time curve (AUC24) to minimum inhibitory concentration (MIC) ratio and vancomycin treatment outcomes in methicillin-resistant Staphylococcus aureus (MRSA) infections. To examine this association and to establish a suitable cut-off value for AUC24/MIC, a multicentre prospective observational study was conducted in patients with MRSA bacteraemia. Data were collected on all patients aged ≥18 years with MRSA bacteraemia treated with vancomycin for ≥72 h without dialysis. The MIC was determined by broth microdilution (BMD) and Etest. Treatment failure was defined as (i) 30-day mortality, (ii) persistent bacteraemia (≥7 days) and (iii) recurrence (≤30 days after completion of therapy). AUC24 was estimated by a Bayesian approach based on individual vancomycin concentrations. The AUC24/MIC cut-off value for differentiating treatment success and failure was calculated by Classification and Regression Tree (CART) analysis. In total, 117 patients were enrolled, among which vancomycin treatment failure occurred in 38 (32.5%). In univariate analysis, high vancomycin MIC and low trough levels were unrelated to treatment outcomes. In the CART analysis, low vancomycin AUC24/MIC [<392.7 (BMD) and <397.2 (Etest)] was associated with treatment failure. In multivariate analysis, low AUC24/MIC was a risk factor for treatment failure [adjusted odds ratio (aOR)=3.50, 95% confidence interval (CI) 1.39-8.82 by BMD; aOR=5.61, 95% CI 2.07-15.24 by Etest]. AUC24/MIC is associated with vancomycin treatment outcomes in MRSA bacteraemia, and seeking individualised AUC24/MIC ratios above target (>400) may improve treatment outcomes.
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Falcón R, Madrid S, Tormo N, Casañ C, Albert E, Gimeno C, Navarro D. Intra- and Interinstitutional Evaluation of an Etest for Vancomycin Minimum Inhibitory Concentration Measurement inStaphylococcus aureusBlood Isolates: Figure 1. Clin Infect Dis 2015; 61:1490-2. [DOI: 10.1093/cid/civ583] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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López-Cortés LE, Velasco C, Retamar P, del Toro MD, Gálvez-Acebal J, de Cueto M, García-Luque I, Caballero FJ, Pascual A, Rodríguez-Baño J. Is reduced vancomycin susceptibility a factor associated with poor prognosis in MSSA bacteraemia? J Antimicrob Chemother 2015; 70:2652-60. [DOI: 10.1093/jac/dkv133] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 04/21/2015] [Indexed: 11/13/2022] Open
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Effects of Frozen Storage on Detection of Intermediate Vancomycin Susceptibility and Heteroresistance in Methicillin-Resistant Staphylococcus aureus Blood Isolates. J Clin Microbiol 2015; 53:2392. [PMID: 25926498 DOI: 10.1128/jcm.00599-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
PURPOSE OF REVIEW Despite concerns regarding efficacy and tolerability, vancomycin continues to be the standard treatment for skin and soft tissue infections (SSTIs) when β-lactam antimicrobials cannot be used. This review sought to establish the role of both old and new alternatives to vancomycin. Methods for achieving optimization of vancomycin therapy are also explored. RECENT FINDINGS Several meta-analyses have demonstrated poorer clinical outcomes when the vancomycin minimum inhibitory concentration approaches the breakpoint of 2 μg/ml. Higher doses should be utilized to optimize pharmacokinetics and pharmacodynamics when higher volumes of distribution occur (e.g. sepsis). Newer agents with established noninferiority to vancomycin include the oxazolidinones linezolid and tedizolid, the lipopeptide daptomycin, the anti-meticillin-resistant Staphylococcus aureus cephalosporin ceftaroline and the glycylcycline tigecycline. Linezolid is thus far the only agent that has been shown to be associated with better clinical and microbiological cure rates. Ceftaroline and tigecycline are broad-spectrum agents best reserved for polymicrobial infections (e.g. diabetic foot infections). SUMMARY When vancomycin is used for the treatment of SSTIs, maximizing the dose should be performed to improve efficacy. Cost is often the main limiting factor with regard to the newer agents, but their suitability for outpatient antimicrobial therapy may counteract this.
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Precision of vancomycin and daptomycin MICs for methicillin-resistant Staphylococcus aureus and effect of subculture and storage. J Clin Microbiol 2014; 52:3898-905. [PMID: 25143569 DOI: 10.1128/jcm.01571-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The reproducibility of vancomycin and daptomycin MICs, measured by broth microdilution (BMD) and Etest, was prospectively assessed for 10 methicillin-resistant Staphylococcus aureus (MRSA) isolates from the blood samples from patients on vancomycin therapy. The isolates were tested at the time of isolation from blood and following 5, 10, and 20 subcultures and at 1, 3, 6, and 12 months of storage at -70 °C. The MICs were determined by Etest and BMD using two different manufacturers (BBL and Difco) of cation-adjusted Mueller-Hinton broth (CA-MHB), and using three different drug powders: vancomycin from Sigma, vancomycin from Novation, and daptomycin from Cubist. The antimicrobial concentrations tested were 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 μg/ml. Two isolates were vancomycin intermediate and daptomycin nonsusceptible, and two isolates had reduced susceptibility to vancomycin (BMD MIC, 1.5 or 2.0 μg/ml). The vancomycin MICs were significantly higher in the BBL CA-MHB than those in the Difco CA-MHB, and with Sigma versus Novation vancomycin powder. The daptomycin MICs were also significantly higher in the BBL CA-MHB. The Etest MICs were significantly higher than those obtained by BMD for vancomycin but not for daptomycin. The average precision of the vancomycin BMD MICs when analyzing 20 results was ± 1.10-fold log2 dilutions, and it was ± 1.67-fold for daptomycin (10 results). The average precision for Etest was ± 1.11-fold for vancomycin and ± 1.16-fold for daptomycin. No significant change in MICs was noted following 5, 10, or 20 subcultures or at up to 6 months of frozen storage. However, the vancomycin MICs alone were significantly lower (0.74-fold) following 12 months of frozen storage. From these data, despite variations in CA-MHB and antimicrobial powder, the MIC result precision was <0.5 log2 dilutions in a single laboratory, suggesting that testing interdilution MICs (e.g., MICs between serial 2-fold dilutions) is a possibility. A more accurate method for measuring vancomycin MIC results is thus possible, but further standardization of BMD testing would be required to achieve this goal.
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Tsao SM, Wang WY, Ko WC, Huang CH, Lu CT, Chuang YC, Liu CY, Liao CH, Chen YS, Liu YC, Chen WY, Jang TN, Lin HC, Chen CM, Shi ZY, Pan SC, Yang JL, Kung HC, Liu CE, Cheng YJ, Liu JW, Sun W, Wang LS, Yu KW, Chiang PC, Lee MH, Lee CM, Hsu GJ, Chen YH, Lu PL, Thomas CYT, Hsueh PR. Trend in vancomycin susceptibility and correlation with molecular characteristics of methicillin-resistant Staphylococcus aureus causing invasive infections in Taiwan: results from the Tigecycline in vitro Surveillance in Taiwan (TIST) study, 2006-2010. Diagn Microbiol Infect Dis 2014; 80:162-7. [PMID: 25053202 DOI: 10.1016/j.diagmicrobio.2014.06.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/01/2014] [Accepted: 06/16/2014] [Indexed: 10/25/2022]
Abstract
This study was intended to investigate the trend in vancomycin susceptibility and correlation with molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) causing invasive infections. A total of 670 MRSA isolates were collected from patients with invasive infections as part of bacterial collection in the Tigecycline in vitro Surveillance in Taiwan (TIST) from 2006 to 2010. MICs of the isolates to vancomycin were determined using the agar dilution method. Characteristics of staphylococcal cassette chromosome mec (SCCmec), mec-associated hypervariable region (dru), and accessory gene regulator (agr) of the isolates were identified by polymerase chain reaction methods. MRSA isolates with SCCmec types I, II, and III were molecularly defined as hospital-associated MRSA (HA-MRSA), and those with SCCmec types IV, V, and VT were assigned as community-associated MRSA (CA-MRSA). All but 1 MRSA isolates exhibited vancomycin MICs ≤1 mg/L. A declining trend in vancomycin MICs among MRSA isolates was noted, which was associated with the decline in proportion of HA-MRSA. The percentage of CA-MRSA increased from 25.6% in 2006 to 46.0% in 2010. An increase in the geometric mean of vancomycin MICs was found in MRSA with particular molecular types such as SCCmec types II and III, agr groups I and II, and dru10-14. A significant correlation among particular molecular types was found, including SCCmecII-agr group II-dru4, SCCmecIII-agr group I-dru11-14, SCCmecIV-agr group II-dru9, and SCCmecVT-agr group I-dru9 and dru11. There was no vancomycin creep among MRSA isolates, and the declining trend of vancomycin MIC against MRSA was attributed to the increasing prevalence of CA-MRSA over time.
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Affiliation(s)
- Shin-Ming Tsao
- Division of Infectious Diseases, Internal Medicine Department, Institute of Microbiology and Immunology, Chung Shan Medical University, and University Hospital, Taichung, Taiwan
| | - Wei-Yao Wang
- Department of Internal Medicine, Fong-Yuan Hospital, Taichung, Taiwan
| | - Wen-Chien Ko
- Department of Medicine, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan
| | - Cheng-Hua Huang
- Division of Infectious Diseases, Department of Internal Medicine, Cathay General Hospital, Taipei, Taiwan
| | - Chin-Te Lu
- Section of Infectious Diseases, Department of Internal Medicine, Lotung Poh-Ai Hospital, Luodong Township, Taiwan
| | - Yin-Ching Chuang
- Department of Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan
| | - Chia-Ying Liu
- Section of Infectious Diseases, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei, Taiwan
| | - Chun-Hsing Liao
- Section of Infectious Diseases, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei, Taiwan
| | - Yao-Shen Chen
- Section of Infectious Diseases, Shuang Ho Hospital, Taipei Medical University and School of Medicine, Taipei, Taiwan; Section of Infectious Diseases, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Yung-Ching Liu
- Section of Infectious Diseases, Shuang Ho Hospital, Taipei Medical University and School of Medicine, Taipei, Taiwan; Section of Infectious Diseases, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Wei-Yu Chen
- Section of Infectious Diseases, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Tsrang-Neng Jang
- Section of Infectious Diseases, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Hsiu-Chen Lin
- Department of Pediatrics, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chih-Ming Chen
- Section of Infectious Diseases, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Wuqi Township, Taiwan
| | - Zhi-Yuan Shi
- Section of Infectious Diseases, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Sung-Ching Pan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jia-Ling Yang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Hsiang-Chi Kung
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chun-Eng Liu
- Section of Infectious Diseases, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan
| | - Yu-Jen Cheng
- Section of Infectious Diseases, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan
| | - Jien-Wei Liu
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University Medical College, Kaohsiung, Taiwan
| | - Wu Sun
- Department of Infection Control, Pao-Chien Hospital, Pingtung, Taiwan
| | - Lih-Shinn Wang
- Section of Infectious Diseases, Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
| | - Kwok-Woon Yu
- Division of Infectious Diseases, Department of Internal Medicine, Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Ping-Cherng Chiang
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Medical Foundation Linkou Branch, Tao-Yuan, Taiwan
| | - Ming-Hsun Lee
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Medical Foundation Linkou Branch, Tao-Yuan, Taiwan
| | - Chun-Ming Lee
- Section of Infectious Diseases, Department of Internal Medicine, Mackay Memorial Hospital, Taipei, Taiwan
| | - Gwo-Jong Hsu
- Division of Infectious Diseases, Department of Internal Medicine, Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi, Taiwan
| | - Yen-Hsu Chen
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Medical University Hospital, and Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Po-Liang Lu
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Medical University Hospital, and Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chang-Yao Tsao Thomas
- Division of Chest Medicine, Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan.
| | - Po-Ren Hsueh
- Departments of Laboratory Medicine and Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
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Heterogeneous vancomycin-intermediate among methicillin resistant Staphylococcus aureus. Med J Armed Forces India 2014; 71:15-8. [PMID: 25609857 DOI: 10.1016/j.mjafi.2014.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Accepted: 03/19/2014] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Hetero-resistance vancomycin intermediate Staphylococcus aureus (hVISA) is phenotype, which on in-vitro susceptibility test is vancomycin susceptible (VSSA) but has a minority population of vancomycin intermediate (VISA). hVISA is responsible for vancomycin treatment failure. Population Analysis Profile- Area under Curve (PAP-AUC) is a test for detection of hVISA; however, this test is unsuitable for clinical microbiology laboratory. Tests, such as Brain Heart Infusion Agar with 6 μg/ml vancomycin (BHIA6V), E test and Macromethod E Test (MET) are available; however reported to have variable results. METHODS 58 clinical isolates of Methicillin resistant S aureus (MRSA) having MIC of vancomycin more than 1 μg/ml by E test and agar dilution were analyzed by PAP-AUC, BHIA6V and MET. RESULT The prevalence of hVISA was 6.9%. hVISA isolates were having vancomycin E test MIC >2 μg/ml. Sensitivity of BHIA6V, MET and E test with MIC >2 μg/ml were 0.75, 0.67 and 1.0 respectively; however, positive predictive values (PPV) were 0.43, 0.4 and 0.27 respectively with PAP-AUC. PAP-AUC ratio correlated with MIC by E test and MET. CONCLUSIONS There is need for screening MRSA isolates showing in-vitro vancomycin susceptibility ≤2 μg/ml by agar dilution method for detection of hVISA. PAP-AUC test is unsuitable for routine laboratory testing. BHIA6V, MET and E test can be used for screening, however have low PPV.
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Sancak B. What is the reason for conflicting results for vancomycin minimum inhibitory concentration values of methicillin-resistant Staphylococcus aureus? SCANDINAVIAN JOURNAL OF INFECTIOUS DISEASES 2014; 46:158-160. [PMID: 24215363 DOI: 10.3109/00365548.2013.847530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- Banu Sancak
- Hacettepe University Medical School, Department of Medical Microbiology , Ankara , Turkey
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Steed ME, Hall AD, Salimnia H, Kaatz GW, Kaye KS, Rybak MJ. Evaluation of Daptomycin Non-Susceptible Staphylococcus aureus for Stability, Population Profiles, mprF Mutations, and Daptomycin Activity. Infect Dis Ther 2013; 2:187-200. [PMID: 25134481 PMCID: PMC4108102 DOI: 10.1007/s40121-013-0021-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Indexed: 12/25/2022] Open
Abstract
Introduction Despite studies examining daptomycin non-susceptible (DNS) Staphylococcus aureus, examination of the stability and population profiles is limited. The objective was to evaluate the stability, population profiles, and daptomycin activity against DNS isolates. Methods The stability of 12 consecutive clinical DNS strains was evaluated by minimum inhibitory concentration (MICs) and population analysis profiles before and after 5 days of serial passage. Two pairs of DNS S. aureus having the same daptomycin MIC but different daptomycin population profiles were evaluated via an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations for 96 h against daptomycin 6 and 10 mg/kg/day. The sequence of mprF was determined for these isolates before and after 96 h of daptomycin exposure in the in vitro PK/PD model. Results Daptomycin MIC values were 2–4 mg/L (via Microscan) for the 12 clinical isolates; 9 were confirmed DNS and 3 were within 1 tube dilution of Microscan (daptomycin MIC 1 mg/L). All were stable to serial passage. There was variation in the isolates susceptibility to daptomycin on population analysis (daptomycin population AUC 14.01–26.85). The killing patterns of daptomycin 6 and 10 mg/kg/day differed between isolates with a left-shift and right-shift population profile to daptomycin. Two strains developed additional mprF mutations during daptomycin exposure in the in vitro PK/PD model resulting in P314L, L826F, S337L and a novel Q326Stop mutation. Conclusions The collection of DNS isolates was stable and displayed variation in susceptibility to daptomycin on population profile. Further research examining this clinical relevance is warranted. Electronic supplementary material The online version of this article (doi:10.1007/s40121-013-0021-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Molly E Steed
- Anti-Infective Research Laboratory, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Avenue, Detroit, MI, 48201, USA
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Kwok GML, O'Donoghue MM, Doddangoudar VC, Ho J, Boost MV. Reduced vancomycin susceptibility in porcine ST9 MRSA isolates. Front Microbiol 2013; 4:316. [PMID: 24298270 PMCID: PMC3829576 DOI: 10.3389/fmicb.2013.00316] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 10/07/2013] [Indexed: 11/13/2022] Open
Abstract
Porcine strains of livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA) have been recognized in many countries and have been shown to be able to cause human infection. Resistance to non-beta lactam antibiotics has been reported but non-susceptibility to vancomycin, which is known to occur in human MRSA, has so far not been observed in LA-MRSA. Such resistance is typically fairly low level involving changes in the cell wall thickness. The development of resistance is usually preceded by presence of a sub-population having an increased MIC, which is selected for by exposure to vancomycin. This study investigated vancomycin susceptibility of one hundred porcine MRSA isolates using three MIC methods including spiral gradient endpoint (SGE) technique which allows visualization of more resistant sub-populations. SGE revealed 16 strains with an MIC above 2.0 mg/L, of which 14 were determined to have MIC 4 mg/L by agar dilution (AD). SGE revealed a further two isolates with MIC < 2 mg/L had a sub-population >2 mg/L. In addition, trailing endpoints not reaching resistance were present in 26 isolates with MIC < 2 mg/L. Sequencing of the genes of the VraSR/GraSR two component systems of ten of the resistant strains for comparison with susceptible strains revealed changes, including the presence of stop codons, in vraS and graR, but these were not consistent in all isolates. Other genetic changes may contribute to vancomycin non-susceptibility and require investigation. As failure to respond to treatment has been reported in clinical isolates with MIC > 1.5 mg/L, the presence of vancomycin non-susceptibility in porcine isolates is of concern and further monitoring of LA-MRSA is essential.
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Affiliation(s)
- Gabriella M L Kwok
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University Kowloon, Hong Kong
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Hu J, Ma XX, Tian Y, Pang L, Cui LZ, Shang H. Reduced vancomycin susceptibility found in methicillin-resistant and methicillin-sensitive Staphylococcus aureus clinical isolates in Northeast China. PLoS One 2013; 8:e73300. [PMID: 24069184 PMCID: PMC3772004 DOI: 10.1371/journal.pone.0073300] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 07/18/2013] [Indexed: 11/18/2022] Open
Abstract
Background Strains of Staphylococcus aureus with an intermediate level of resistance to vancomycin (vancomycin-intermediate S. aureus, or VISA) or which contain subpopulations of mixed susceptibility (heterogeneous VISA, or hVISA) have been reported worldwide. However, the prevalence of VISA and hVISA infections in Northeast China is unknown. From 2007 through 2010, we surveyed the vancomycin susceptibility of methicillin-resistant and methicillin-sensitive S. aureus (MRSA and MSSA, respectively) clinical isolates in Northeast China. Methods S. aureus clinical isolates (369 MRSA and 388 MSSA) were screened for hVISA and VISA on brain heart infusion agar containing 3 μg/mL vancomycin, and their identity confirmed using a modified population analysis profile-area under the curve method and broth microdilution. All hVISA and VISA isolates were characterized genotypically and phenotypically. Results Ten percent and 0.5 percent of the isolates were hVISA and VISA, respectively. The proportion of hVISA among MSSA isolates for the entire study period was 4.1%, but increased significantly year-by-year, from 1.2% in 2007 to 7.2% in 2010. The predominant sources of hVISA and VISA isolates were sputum (56.3%), pus (18.8%), and blood (8.8%). Molecular typing of hVISA and VISA strains revealed that, taken together, 80% contained the accessory gene regulator (agr) group II, and of these, 85.7% of the MR-hVISA and MR-VISA strains were staphylococcal cassette chromosome mec (SCCmec) type II. The adherence ability of all hVISA and VISA strains was reduced compared with that of vancomycin-susceptible strains, shown by biofilm assay. Conclusions The percentage of hVISA strains was high and increased each year. The proportion of hVISA among MSSA specifically also increased significantly each year. In isolates collected from diverse infection sites, hVISA and VISA strains were found predominantly in sputum, pus, and blood, in descending order. Testing for vancomycin susceptibility should include both MRSA and MSSA isolates collected from different clinical sites.
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Affiliation(s)
- Jian Hu
- Department of Medical Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, People's Republic of China
- Department of Clinical Laboratory, Yixing Hospital of Traditional Chinese Medicine, Yixing, Jiangsu, People's Republic of China
| | - Xiao Xue Ma
- Department of Medical Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, People's Republic of China
| | - Yuan Tian
- Department of Medical Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, People's Republic of China
| | - Long Pang
- Department of Medical Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, People's Republic of China
| | - Long Zhu Cui
- Research Center for Anti-infectious Drugs, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Hong Shang
- Department of Clinical Laboratory, First Affiliated Hospital of China Medical University, Shenyang, People's Republic of China
- * E-mail:
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The detection and clinical impact of vancomycin MIC among patients with methicillin-resistant Staphylococcus aureus bacteremia. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2013; 46:315-6. [DOI: 10.1016/j.jmii.2013.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 03/15/2013] [Indexed: 11/17/2022]
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Lawes T, Edwards B, Gould IM. Comment on: Lack of upward creep of glycopeptide MICs for methicillin-resistant Staphylococcus aureus (MRSA) isolated in the UK and Ireland 2001-07. J Antimicrob Chemother 2013; 68:1691-2. [DOI: 10.1093/jac/dkt070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Reynolds R, Hope R, Warner M, MacGowan AP, Livermore DM, Ellington MJ. Lack of upward creep of glycopeptide MICs for methicillin-resistant Staphylococcus aureus (MRSA) isolated in the UK and Ireland 2001-07--authors' response. J Antimicrob Chemother 2013; 68:1693-4. [DOI: 10.1093/jac/dkt119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bryant KA, Roberts AL, Rupp ME, Anderson JR, Lyden ER, Fey PD, Van Schooneveld TC. Susceptibility of enterococci to daptomycin is dependent upon testing methodology. Diagn Microbiol Infect Dis 2013; 76:497-501. [PMID: 23719086 DOI: 10.1016/j.diagmicrobio.2013.04.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 04/17/2013] [Accepted: 04/21/2013] [Indexed: 12/17/2022]
Abstract
An increase in daptomycin nonsusceptible enterococci (DNSE) was noted in our institution (8.3% 2008 to 34.5% 2011) using MicroScan methods which may overestimate DNSE prevalence. DNSE (N = 150) from the clinical laboratory (2008-2011) underwent susceptibility testing using broth microdilution (BMD), Etest, Sensititire, MicroScan prompt (MSP), and MicroScan turbidity (MST) with only 20% of isolates confirmed as nonsusceptible. Categorical and essential agreement were highest with MSP and MST, but both missed the majority of resistant isolates (70% and 87% missed). Etest MIC values were statistically higher, more likely to be nonsusceptible, had the lowest very major error rate (37%), and the highest falsely nonsusceptible rate (22%). Sensititre MIC values were not statistically different from BMD, but missed 57% of DNSE. PFGE analysis did not define a clonal outbreak. These findings suggest that MicroScan methods overestimate nonsusceptibility, and the lack of correlation between methods raises questions regarding which method is most effective at confirming nonsusceptibility.
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Affiliation(s)
- Kendall A Bryant
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 984031 Nebraska Medical Center, Omaha, NE 68198-4031, USA
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Gould IM. Treatment of bacteraemia: meticillin-resistant Staphylococcus aureus (MRSA) to vancomycin-resistant S. aureus (VRSA). Int J Antimicrob Agents 2013; 42 Suppl:S17-21. [PMID: 23664580 DOI: 10.1016/j.ijantimicag.2013.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Around the world, Staphylococcus aureus remains a dominant cause of bacteraemia. Whilst meticillin resistance remains the major phenotype of concern, various levels of reduced glycopeptide susceptibility are emerging with increasing frequency. The most common MRSA phenotypes now have raised vancomycin MICs within the susceptible range (MICs of 1-2mg/L). This phenomenon, known as MIC creep, is hotly contested and often denied. Key to detecting MIC creep may be to examine isolates fresh, as freezing can allow reversion to wild-type MIC, presumably by loss of mutations. Treatment failure is common with vancomycin and it is uncertain whether higher doses are beneficial. At the other extreme, when enough mutations have accumulated, full VISA status is achieved, although this can also be unstable on storage. Heteroresistant and VISA strains can be considered the inevitable end result of continued MIC creep and are even more likely to fail glycopeptide treatment. Currently full vancomycin resistance is uncommon, with only approximately 20 strains described and confirmed worldwide. Empirical treatment for patients with undefined Gram-positive sepsis can undoubtedly be improved by knowledge of MRSA status, so this is a potential advantage of hospital admission screening. If a patient is risk-assessed or screen-positive for MRSA, and infection is not serious, then vancomycin or teicoplanin is appropriate empirical therapy, providing loading doses are given to achieve therapeutic concentrations immediately (trough 15 mg/L). For life-threatening infections, the glycopeptides are inadequate unless the isolate is likely to be fully susceptible (Etest<1.5mg/L). If not, daptomycin (8-10mg/L) can be used as monotherapy but the MIC should be measured as soon as possible.
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Affiliation(s)
- I M Gould
- Department of Medical Microbiology, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN, UK.
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Bal A, Garau J, Gould I, Liao C, Mazzei T, Nimmo G, Soriano A, Stefani S, Tenover F. Vancomycin in the treatment of meticillin-resistant Staphylococcus aureus (MRSA) infection: End of an era? J Glob Antimicrob Resist 2013; 1:23-30. [DOI: 10.1016/j.jgar.2013.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 01/24/2013] [Indexed: 10/27/2022] Open
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