Current practices and challenges of outpatient parenteral antimicrobial therapy: a narrative review

Extended hospitalization for infection management increases inpatient care costs and the risk of healthcare-associated adverse events, including infections. The growing global demand for healthcare, the diminishing availability of hospital beds and an increasing patient preference for care within their own home have been the primary drivers of the expansion of hospital-in-the-home programmes. Such programmes include the use of IV antimicrobials in outpatient settings, known as outpatient parenteral antimicrobial therapy (OPAT). However, OPAT practices vary globally. This review article aims to describe the current OPAT practices and challenges worldwide. OPAT practice begins with patient evaluation and selection using eligibility criteria, which requires collaboration between the interdisciplinary OPAT team, patients and caregivers. Depending on care requirements, eligible patients may be enrolled to various models of care, receiving medication by healthcare professionals at outpatient infusion centres, hospital clinics, home visits or through self-administration. OPAT can be used for the management of many infections where an effective oral treatment option is lacking. Various classes of parenteral antimicrobials, including β-lactams, aminoglycosides, glycopeptides, fluoroquinolones and antifungals such as echinocandins, are used globally in OPAT practice. Despite its benefits, OPAT has numerous challenges, including complications from medication administration devices, antimicrobial side effects, monitoring requirements, antimicrobial instability, patient non-adherence, patient OPAT rejection, and challenges related to OPAT team structure and administration, all of which impact its outcome. A negative outcome could include unplanned hospital readmission. Future research should focus on mitigating these challenges to enable optimization of the OPAT service and thereby maximize the documented benefits for the healthcare system, patients and healthcare providers.

Feasibility of individualised patient modelling for continuous vancomycin infusions in outpatient antimicrobial therapy, a retrospective study

BACKGROUND

The area under the curve (AUC) to minimum inhibitory concentration (MIC) ratio is proposed as a therapeutic drug-monitoring parameter for dosing vancomycin continuous infusion in methicillin-resistant Staphylococcus aureus (MRSA) infection. Individualised pharmacokinetic-pharmacodynamic (PK/PD) calculation of AUC24 may better represent therapeutic dosing than current Therapeutic Drug Monitoring (TDM) practices, targeting a Steady State Concentration of 15-25 mg/L.

AIM

To compare real world TDM practice to theoretical, individualised, PK/PD target parameters utilising Bayesian predictions to steady state concentrations (Css) for outpatients on continuous vancomycin infusions.

METHOD

A retrospective single centre study was conducted at a tertiary hospital on adult patients, enrolled in an outpatient parenteral antimicrobial therapy (OPAT) program, receiving vancomycin infusions for MRSA infection. Retrospective Bayesian dosing was modelled to target PK/PD parameters and compared to real world data.

RESULTS

Fifteen patients were evaluated with 53% (8/15) achieved target CSS during hospitalisation, and 83% (13/15) as outpatient. Median Bayesian AUC/MIC was 613 mg.h/L with CSS 25 mg/L. Patients suffering an Acute Kidney Injury (33%) had higher AUC0-24/MIC values. Retrospective Bayesian modelling demonstrated on median 250 mg/24 h lower doses than that administered was required (R2 = 0.81) which achieved AUC24/MIC median 444.8 (range 405-460) mg.h/L and CSS 18.8 (range 16.8-20.4) mg/L.

CONCLUSION

Bayesian modelling could assist in obtaining more timely target parameters at lower doses for patients receiving continuous vancomycin infusion as part of an OPAT program, which may beget fewer adverse effects. Utilisation of personalised predictive modelling may optimise vancomycin prescribing, achieving earlier target concentrations as compared to empiric dosing regimens.

A review of evidence, antimicrobial stability, and feasibility considerations for OPAT continuous infusion

Outpatient parenteral antimicrobial therapy (OPAT) has been widely used in clinical practice for many decades because of its associated cost savings, reductions in inpatient hospital days, and decreases in hospital-associated infections. Despite this long history, evolving practice patterns and new drug delivery devices continue to present challenges as well as opportunities for clinicians when designing appropriate outpatient antimicrobial regimens. One such change is the increasing use of extended and continuous infusion (CI) of antimicrobials to optimize the achievement of pharmacokinetic and pharmacodynamic targets. Elastomeric devices are also becoming increasingly popular in OPAT, including for the delivery of CI. In this article, we review the clinical evidence for CI in OPAT, as well as practical considerations of patient preferences, cost, and antimicrobial stability.

Clinical Efficacy and Safety of Vancomycin Continuous Infusion in Patients Treated at Home in an Outpatient Parenteral Antimicrobial Therapy Program

Vancomycin is commonly used in outpatient parenteral antimicrobial therapy (OPAT) of Gram-positive infections. Therapeutic drug monitoring and adverse event monitoring pose a challenge. Outcome data of vancomycin in OPAT (vOPAT) are limited. The study aim was to report the safety and efficacy of a structured vOPAT program implemented in the University Hospitals Leuven. The program provides continuous elastomeric infusion of vancomycin at home with biweekly follow-up at the outpatient clinic. Demographics, clinical, biochemical and treatment parameters, target attainment parameters and clinical outcomes were recorded. An e-survey was conducted to assess patient satisfaction. Thirty-five vOPAT episodes in 32 patients were included. During 206 follow-up consultations, 203 plasma concentration measurements were registered with a median vancomycin plasma concentration of 22.5 mg/L (range 6.6–32.0). The majority of concentrations (68.5%) were within the therapeutic range (20.0–25.0 mg/L). Adverse event rates, including drug- (5.7%) and catheter-related (5.7%) events, were low. For 32 vOPAT episodes, a clinical cure rate of 100% was observed. All patients who completed the e-survey were satisfied with their vOPAT course. These findings show that a structured vOPAT program with rigorous follow-up provides safe and effective ambulatory treatment of patients with vancomycin in continuous infusion.

When There Is No Trough: Use and Outcomes of Continuous-Infusion Vancomycin at a Free-Standing Children's Hospital

OBJECTIVE

There is minimal published literature regarding the use of continuous-infusion vancomycin (CIV) in children. The objective of this study was to describe the use, dosing requirements, and outcomes of CIV at a free-standing children's hospital.

METHODS

This is a retrospective review of patients who received CIV while admitted to Nationwide Children's Hospital between July 1, 2010, and June 30, 2020. The total daily dose (TDD) of vancomycin required to attain a target serum vancomycin concentration (SVC) was compared between CIV and intermittent-infusion vancomycin (IIV) administration regimens. Safety outcomes and treatment failure were also explored.

RESULTS

Fourteen patients (77% male) with a median age of 7 years (IQR = 1, 10 years) were included. Most patients (71%) were started on CIV in anticipation of outpatient parenteral antimicrobial therapy. The median TDD required to achieve a target SVC was higher with IIV compared with CIV (82.4 mg/kg/day vs 50.5 mg/kg/day; p = 0.02). Despite higher TDD with IIV, median SVC with IIV was similar to SVC with CIV (16.6 mg/L vs 17.6 mg/L; p = 2.00). There were no safety concerns or therapeutic failures identified with CIV.

CONCLUSIONS

Continuous-infusion vancomycin was a well-tolerated and effective alternative to IIV for the patients included in this study. The TDD of vancomycin required to achieve a target SVC was lower in patients receiving CIV compared with those receiving IIV.

Retrospective multicentre matched cohort study comparing safety and efficacy outcomes of intermittent-infusion versus continuous-infusion vancomycin

BACKGROUND

Patients with good renal function receiving intermittent-infusion vancomycin (IIV) may require total daily doses ≥4 g to achieve trough concentrations of 15-20 mg/L, increasing the risk of vancomycin-associated nephrotoxicity. Continuous-infusion vancomycin (CIV) may be associated with a lower risk of vancomycin-associated nephrotoxicity compared with IIV, but studies comparing safety of both dosing strategies are lacking.

OBJECTIVES

To compare the risk of nephrotoxicity with CIV versus IIV when target concentration ranges were the same with both dosing modalities.

METHODS

A retrospective multicentre matched cohort study of admitted patients between 1 January 2010 and 31 December 2016 was completed. Adult patients who received ≥48 h of vancomycin with at least one steady-state vancomycin concentration were eligible. The primary outcome was to compare the rates of nephrotoxic risk and renal injury, defined by the RIFLE criteria, between CIV and IIV.

RESULTS

Of 2136 patients who received vancomycin during the study period, 146 CIV patients were eligible and matched to 146 IIV patients. After adjustment of potential confounders, CIV was found to have a lower odds of developing nephrotoxic risk (OR 0.42, 95% CI 0.21-0.98, P = 0.025) and renal injury (OR 0.19, 95% CI 0.05-0.59, P = 0.004).

CONCLUSIONS

CIV is associated with a lower odds of nephrotoxicity compared with IIV when targeting the same concentration range and should be an alternative dosing strategy for patients who will receive prolonged therapy or require >4 g/day to achieve therapeutic levels.

Evaluating the safety and effectiveness of a nurse-led outpatient virtual IV vancomycin monitoring clinic: a retrospective cohort study

Background

Outpatient parenteral antimicrobial therapy (OPAT) with vancomycin is a common treatment modality for certain Gram-positive infections. Data regarding the safety of various models of delivery are limited.

Objectives

To review outcomes of a nurse-led OPAT vancomycin monitoring service.

Methods

This was a retrospective cohort study of consecutive patients referred to a nurse-led OPAT vancomycin clinic from December 2015 to March 2018. Patients were administered IV vancomycin in the home with active laboratory monitoring of vancomycin trough levels, renal function and complete blood count using an integrated electronic database linked with community laboratories (virtual vancomycin clinic, VVC). Monitoring was coordinated by nurses with physician approval of recommended dosing changes. Data were extracted from the electronic medical record. Demographics; clinical indication; microbial aetiology; culture source; antimicrobial regimen(s); serum creatinine and vancomycin trough values; initiation, discharge and completion dates; hospitalizations; adverse events; and outcomes were all evaluated.

Results

Two hundred and seventy-five patients underwent a total of 301 courses of OPAT with vancomycin; 285 courses were completed. The rate of treatment discontinuation due to adverse effects was 33/301 (11.0%), with 15/33 (45.5%) being due to renal adverse effects (15/301 [5.0%] of episodes). Two of 15 (18.2%) patients developed stage 2 acute kidney injury (AKI), and no patients had stage 3 AKI or required haemodialysis. Nine of 301 (3.0%) required readmission for treatment failure. Nursing costs associated with monitoring were $63.93 CAD/patient ($48.43 USD).

Conclusions

A nurse-led VVC was a safe, effective and inexpensive modality for administering outpatient vancomycin.

Optimizing Antibiotic Treatment Strategies for Neonates and Children: Does Implementing Extended or Prolonged Infusion Provide any Advantage?

Optimizing the use of antibiotics has become mandatory, particularly for the pediatric population where limited options are currently available. Selecting the dosing strategy may improve overall outcomes and limit the further development of antimicrobial resistance. Time-dependent antibiotics optimize their free concentration above the minimal inhibitory concentration (MIC) when administered by continuous infusion, however evidences from literature are still insufficient to recommend its widespread adoption. The aim of this review is to assess the state-of-the-art of intermittent versus prolonged intravenous administration of antibiotics in children and neonates with bacterial infections. We identified and reviewed relevant literature by searching PubMed, from 1 January 1 2000 to 15 April 2020. We included studies comparing intermittent versus prolonged/continuous antibiotic infusion, among the pediatric population. Nine relevant articles were selected, including RCTs, prospective and retrospective studies focusing on different infusion strategies of vancomycin, piperacillin/tazobactam, ceftazidime, cefepime and meropenem in the pediatric population. Prolonged and continuous infusions of antibiotics showed a greater probability of target attainment as compared to intermittent infusion regimens, with generally good clinical outcomes and safety profiles, however its impact in terms on efficacy, feasibility and toxicity is still open, with few studies led on children and adult data not being fully extendable.

Updated good practice recommendations for outpatient parenteral antimicrobial therapy (OPAT) in adults and children in the UK

UK good practice recommendations for outpatient parenteral antimicrobial therapy (OPAT) were published in 2012 and 2015 for adult and paediatric patients, respectively. Here we update the initial good practice recommendations in a combined document based on a further review of the OPAT literature and an extensive consultation process. As with the previous good practice recommendations, these updated recommendations are intended to provide pragmatic guidance for new and established OPAT services across a range of settings and to act as a set of quality indicators for service evaluation and quality improvement.

Vancomycin Dosing and Monitoring: Critical Evaluation of the Current Practice

After more than six decades of its use as the mainstay antibiotic for the treatment of multidrug-resistant Gram-positive bacterial infections, dosing and monitoring of vancomycin therapy have not been optimized. The current vancomycin therapeutic guidelines recommend empiric doses of 15-20 mg/kg administered by intermittent infusion every 8-12 h in patients with normal kidney function. Additionally, the guidelines recommend trough concentration of 15-20 mg/L as a therapeutic goal for adult patients with severe infections. This review critically discusses the current guidelines considering the basic pharmacokinetics and pharmacodynamics of vancomycin and the recent published reports from clinical studies. More in-depth discussion will be focused on (1) providing evidence of advantages of administering vancomycin by continuous infusion compared to intermittent infusion; (2) revising the current practice of trough-only monitoring versus the area under concentration-time curve (AUC); and (3) assessing the current practice of weight-based dosing versus AUC-based dosing. Using the gathered information presented in this paper, two user-friendly and scientifically based dosing strategies are proposed to improve the efficiency of vancomycin dosing while avoiding the risk of nephrotoxicity and minimizing the cost of therapeutic drug monitoring.

Prospective evaluation of a continuous infusion vancomycin dosing nomogram in critically ill patients undergoing continuous venovenous haemofiltration

Objectives

The most optimal method of attaining therapeutic vancomycin concentrations during continuous venovenous haemofiltration (CVVH) remains unclear. Studies have shown continuous infusion vancomycin (CIV) achieves target concentrations more rapidly and consistently when compared with intermittent infusion. Positive correlations between CVVH intensity and vancomycin clearance (CLvanc) have been noted. This study is the first to evaluate a CIV regimen in patients undergoing CVVH that incorporates weight-based CVVH intensity (mL/kg/h) into the dosing nomogram.

Methods

This was a prospective, observational study of patients undergoing CVVH and receiving CIV based on the nomogram. The primary outcome was achievement of a therapeutic vancomycin concentration (15-25 mg/L) at 24 h. Secondary outcomes included the achievement of therapeutic concentrations at 48 and 72 h.

Results

The nomogram was analysed in 52 critically ill adults. Vancomycin concentrations were therapeutic in 43/52 patients (82.7%) at 24 h. Of the nine patients who were not therapeutic at 24 h, seven were supratherapeutic and two were subtherapeutic. The mean (SD) concentration was 20.1 (4.2)  mg/L at 24 h, 20.7 (3.7) mg/L at 48 h and 21.9 (3.5)  mg/L at 72 h. Patients with CVVH intensity >20 mL/kg/h experienced higher CLvanc at 24 h compared with patients with CVVH intensity <20 mL/kg/h (3.1 versus 2.6 L/h; P = 0.013).

Conclusions

By incorporating CVVH intensity into the CIV dosing nomogram, the majority of patients achieved therapeutic concentrations at 24 h and maintained them within range at 48 and 72 h. Additional studies are required to validate this nomogram before widespread implementation may be considered.

Influence of Mechanical Ventilation on the Pharmacokinetics of Vancomycin Administered by Continuous Infusion in Critically Ill Patients

Pathophysiological changes involved in drug disposition in critically ill patients should be considered in order to optimize the dosing of vancomycin administered by continuous infusion, and certain strategies must be applied to reach therapeutic targets on the first day of treatment. The aim of this study was to develop a population pharmacokinetic model of vancomycin to determine clinical covariates, including mechanical ventilation, that influence the wide variability of this antimicrobial. Plasma vancomycin concentrations from 54 critically ill patients were analyzed simultaneously by a population pharmacokinetic approach. A nomogram for dosing recommendations was developed and was internally evaluated through stochastic simulations. The plasma vancomycin concentration-versus-time data were best described by a one-compartment open model with exponential interindividual variability associated with vancomycin clearance and the volume of distribution. Residual error followed a homoscedastic trend. Creatinine clearance and body weight significantly dropped the objective function value, showing their influence on vancomycin clearance and the volume of distribution, respectively. Characterization based on the presence of mechanical ventilation demonstrated a 20% decrease in vancomycin clearance. External validation (n = 18) was performed to evaluate the predictive ability of the model; median bias and precision values were 0.7 mg/liter (95% confidence interval [CI], -0.4, 1.7) and 5.9 mg/liter (95% CI, 5.4, 6.4), respectively. A population pharmacokinetic model was developed for the administration of vancomycin by continuous infusion to critically ill patients, demonstrating the influence of creatinine clearance and mechanical ventilation on vancomycin clearance, as well as the implications for targeting dosing rates to reach the therapeutic range (20 to 30 mg/liter).

Optimizing the Clinical Use of Vancomycin

The increasing number of infections produced by beta-lactam-resistant Gram-positive bacteria and the morbidity secondary to these infections make it necessary to optimize the use of vancomycin. In 2009, the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Disease Pharmacists published specific guidelines about vancomycin dosage and monitoring. However, these guidelines have not been updated in the past 6 years. This review analyzes the new available information about vancomycin published in recent years regarding pharmacokinetics and pharmacodynamics, serum concentration monitoring, and optimal vancomycin dosing in special situations (obese people, burn patients, renal replacement therapy, among others). Vancomycin efficacy is linked to a correct dosage which should aim to reach an area under the curve (AUC)/MIC ratio of ≥400; serum trough levels of 15 to 20 mg/liter are considered a surrogate marker of an AUC/MIC ratio of ≥400 for a MIC of ≤1 mg/liter. For Staphylococcus aureus strains presenting with a MIC >1 mg/liter, an alternative agent should be considered. Vancomycin doses must be adjusted according to body weight and the plasma trough levels of the drug. Nephrotoxicity has been associated with target vancomycin trough levels above 15 mg/liter. Continuous infusion is an option, especially for patients at high risk of renal impairment or unstable vancomycin clearance. In such cases, vancomycin plasma steady-state level and creatinine monitoring are strongly indicated.

Continuous versus intermittent infusion of vancomycin in adult patients: A systematic review and meta-analysis

Continuous infusion of vancomycin (CIV) and intermittent infusion of vancomycin (IIV) are two major administration strategies in clinical settings. However, previous articles comparing the efficacy and safety of CIV versus IIV showed inconsistent results. Therefore, a meta-analysis was conducted to compare the efficacy and safety of CIV and IIV. PubMed, the Cochrane Library and Web of Science up to June 2015 were searched using the keywords 'vancomycin', 'intravenous', 'parenteral', 'continuous', 'intermittent', 'discontinuous', 'infusion', 'administration' and 'dosing'. Eleven studies were included in the meta-analysis. Neither heterogeneity nor publication bias were observed. Patients treated with CIV had a significantly lower incidence of nephrotoxicity compared with patients receiving IIV [risk ratio (RR)=0.61, 95% confidence interval (CI) 0.47-0.80; P<0.001]. No significant difference in treatment failure between the two groups was detected. Mortality between patients receiving CIV and patients receiving IIV was similar (RR=1.15, 95% CI 0.85-1.54; P=0.365). This meta-analysis showed that CIV had superior safety compared with IIV, whilst the clinical efficacy was not significantly different. A further multicentre, randomised controlled trial is required to confirm these results.

Continuous infusion vs intermittent vancomycin in neurosurgical intensive care unit patients

PURPOSE

Target plasma level achievement has remained a challenge in neurosurgical intensive care unit patients receiving intravenous vancomycin. We evaluated continuous infusion (CI) and intermittent vancomycin dosing strategies in these patients.

METHODS

This retrospective cohort compared CI vancomycin (target random levels, 20-30 mg/L) to intermittent vancomycin (target troughs, 15-20 mg/L) in regards to achievement of target plasma levels, nephrotoxicity, pharmacodynamic target attainment, and cost savings in 130 patients.

RESULTS

Continuous infusion resulted in greater achievement of goal plasma concentrations at the first steady-state level (40 vs 21.5%, P = .02), more rapid achievement of goal plasma concentrations (2.04 vs 3.76 days, P < .0001), and increased time within therapeutic range (55% vs 34%, P < .0001) but no significant difference in nephrotoxicity (15.4% vs 21.5%, P = .5). Continuous infusion improved pharmacodynamic target attainment (92.3% vs 30.8%, P < .0001) and also reduced levels drawn (3.8 vs 5.7, P = .0007), dose adjustments (1.4 vs 2.4, P = .0006), days of therapy (10.4 vs 14.1, P = .01), and mean total daily dose requirements (33 vs 35.7 mg/kg, P < .0001) per patient.

CONCLUSIONS

Continuous infusion appears beneficial for improving attainment of target plasma concentrations, pharmacodynamic goals, and financial burden, without increasing risk of acute kidney injury.

The pharmacokinetic/pharmacodynamic rationale for administering vancomycin via continuous infusion

WHAT IS KNOWN AND OBJECTIVE

Vancomycin is administered via intermittent infusion (II) almost exclusively in the United States, whereas continuous infusion (CI) dosing methods are used regularly in many European countries. The purpose of this literature analysis is to review current evidence regarding the advantages and disadvantages of CI vancomycin in relation to II, based on the pharmacokinetic and pharmacodynamic aspects of dosing and monitoring therapy, and to identify current practices of CI vancomycin dosing.

METHODS

Medline, Cochrane and GoogleScholar databases were searched using vancomycin as a MeSH term, along with continuous and infusion in all fields, which identified 136 citations. A second search added the terms intermittent and survey, producing nine additional articles. All articles that reported an assessment of CI or II vancomycin administration in adult patients, based on clinical, pharmacokinetic, cost or monitoring considerations, were identified. A total of 43 publications were determined to be suitable for final analysis and possible inclusion in the report.

RESULTS AND DISCUSSION

A meta-analysis of six studies concluded that CI vancomycin was associated with a lower relative risk of kidney injury than II therapy, although other studies reported equivocal findings. The results of several clinical studies suggest that CI vancomycin produces clinical outcomes that are comparable to II. Current vancomycin consensus guidelines promote aggressive dosing to achieve trough levels of 10-15 or 15-20 mg/L, but also include recommendations to target a daily area under the curve (AUC24 ) to minimum inhibitory concentration (MIC) ratio of at least 400. Because vancomycin is a non-concentration-dependent antibiotic, it might be more prudent to monitor steady-state serum concentrations (Css ) during a CI rather than trough concentrations during II, due to the questionable correlation between measured trough concentration and AUC. From a pharmacokinetic/pharmacodynamic perspective, vancomycin dosing and monitoring practices associated with CI offer potentially greater reliability than II. A major disadvantage of CI involves the possibility of having to intravenously co-administer another drug that might not be compatible with vancomycin.

WHAT IS NEW AND CONCLUSION

Continuous infusion vancomycin therapy offers the advantage of Css monitoring, thus avoiding the variabilities associated with the timing of trough levels. Current CI practices include a loading dose of 15-20 mg/kg followed by an infusion of 10-40 mg/kg/day based on the patient's renal function, with a target Css of about 20-30 mg/L. An alternative approach to weight-based (mg/kg) CI dosing is to calculate the dose from an estimation of the patient's vancomycin clearance (in L/h), derived from creatinine clearance (CrCl) via the equation (CrCl∙0·041) + 0·22. The daily dose is then determined by multiplying vancomycin clearance (in L/h) by the desired AUC24 . A new CI vancomycin dosing chart includes clearance-based dosing recommendations for Css values ranging from 17·5 to 27·5 mg/L or AUC24 values ranging from 420 to 660 mg h/L. Although sufficient data already exist to support the use of CI vancomycin as a reasonable therapeutic alternative to II, there is still much to learn about administering the drug in this fashion.

Vancomycin-associated renal dysfunction: where are we now?

Vancomycin has been in clinical use for over 60 years, during which time renal toxicity has been well documented. Multiple risk factors and outcomes are associated with vancomycin-related nephrotoxicity. Risk factors include vancomycin exposure (trough levels 15 mg/L or higher, larger area under the curve, duration of therapy), host susceptibility to vancomycin (increased body weight, preexisting renal dysfunction, critical illness), and concurrent nephrotoxin therapy. Nephrotoxicity is associated with prolonged hospital stays, mortality, and the need for renal replacement therapy. To what degree vancomycin-associated nephrotoxicity exacerbates these adverse clinical outcomes remains unclear. This article reviews the current evidence on vancomycin-associated nephrotoxicity and explores future research directions with potential implications for improved patient safety.

Treatment options for methicillin-resistant Staphylococcus aureus (MRSA) infection: Where are we now?

Methicillin-resistant Staphylococcus aureus (MRSA) infection continues to be a substantial global problem with significant associated morbidity and mortality. This review summarises the discussions that took place at the 4th MRSA Consensus Conference in relation to the current treatment options for serious MRSA infections and how to optimise whichever therapy is embarked upon. It highlights the many challenges faced by both the laboratory and clinicians in the diagnosis and treatment of MRSA infections.