Minyon Avent

Current use of aminoglycosides: indications, pharmacokinetics and monitoring for toxicity

The new Australian Therapeutic Guidelines: Antibiotic, version 14 have revised the recommendations for the use and monitoring of aminoglycosides. The guidelines have clear distinctions between empirical and directed therapy as well as revised recommendations about the monitoring of aminoglycosides. This has led many clinicians to review their current practice with regard to the use of aminoglycosides. This review summarizes why aminoglycosides are still a valid treatment option and discusses the rationale for current dosing regimens in Gram‐negative infections. In particular it focuses on the various methods for monitoring aminoglycosides that are currently being used. The aminoglycoside monitoring methods can be categorized into three groups: linear regression analysis (one compartment model), population methods and Bayesian estimation procedures. Although the population methods are easy to use and require minimal resources they can recommend clinically inappropriate doses as they have constant pharmacokinetic parameters and are not valid in special population groups, that is, renal impairment. The linear regression and Bayesian methods recommend more accurate dosage regimens; however, they require additional resources, such as information technology and healthcare personnel with background training in pharmacokinetics. The Bayesian methods offer additional advantages, such as calculation of doses based on a single serum concentration and optimization of the patients previous pharmacokinetic data, in order to determine subsequent dosage regimens. We recommend the Bayesian estimation procedures be used, wherever feasible. However, they require the expertise of healthcare practitioners with a good understanding of pharmacokinetic principles, such as clinical pharmacists/clinical pharmacologists, in order to make appropriate recommendations.

Vancomycin therapeutics and monitoring: a contemporary approach

Vancomycin remains a clinically useful antibiotic despite the advent of several alternative drugs. Optimising vancomycin therapy with therapeutic drug monitoring is widely recommended. The aim of therapeutic drug monitoring is to help the clinician to achieve target pharmacodynamic parameters in the case of vancomycin, an area under the concentration time curve/minimum inhibitory concentration ratio of ≥400. Vancomycin monitoring methods can be categorised into four categories: empiric trough concentrations; linear regression analysis (one‐compartment model), population methods and Bayesian estimation procedures. Although the empiric trough concentrations and population methods are easy to use and require minimal resources, there are large differences in the published vancomycin model parameters. This demonstrates that there is great variance in pharmacokinetic parameters between the models and a single vancomycin model cannot be applied to all patient populations. The linear regression and Bayesian methods recommended more accurate dosage regimens; however, they require additional resources such as information technology and healthcare personnel with background training in pharmacokinetics. The Bayesian methods offered additional advantages such as calculation of doses based on a single‐serum concentration and optimisation of the patients previous pharmacokinetic data to determine subsequent dosage regimens. Computerised programs, utilising the Bayesian estimation procedures, are able to achieve target concentrations in a greater percentage of patients earlier in the course of therapy than the empiric trough concentrations and population methods. We recommend the use of these programs providing there is appropriate expertise available to make appropriate recommendations.

A Comparison of High versus Low Dose Recombinant Human Erythropoietin versus Blood Transfusion in the Management of Anaemia of Prematurity in a Developing Country

The purpose of this study was to evaluate the effectiveness of early treatment with erythropoietin (EPO) in two different treatment regimes (high vs. low dose) in comparison to the conventional treatment of packed red blood cell (PRBC) transfusions in the management of anaemia of prematurity in a country with limited resources. An open controlled trial was conducted on 93 preterm infants (7 days postnatal age, 900-1500 g birthweight). Patients were randomly assigned either to a low dose (250 IU/kg), a high dose (400 IU/kg), or a control group. EPO was administered subcutaneously three times a week and all infants received 6 mg/kg iron orally from study entry to endpoint of therapy. Haematological parameters were measured and compared. The success was defined as an absence of transfusions and a haematocrit that did not fall below 30 per cent during the time period that the infants were in the study. The three groups were statistically comparable at study entry with respect to gestational age, birthweight, Apgar scores, and haematological values. Over the period that the infants were in the study, 75 per cent of the low dose group and 71 per cent of the high dose group met the criteria for success compared with 40 per cent in the control group (p < 0.001). However, there was no significant difference in the number of transfusions when the low and high EPO dose groups (9.5 per cent) were combined and compared with the control group (26.7 per cent) p = 0.0587. It was concluded that in stable infants, 900-1500 g, where phlebotomy losses are minimized and stringent transfusion guidelines are adhered to, EPO does not significantly decrease the number of transfusions. A conservative approach in the management of anaemia of prematurity, is a viable alternative in areas with limited resources.

Antibiotic duration and timing of the switch from intravenous to oral route for bacterial infections in children: systematic review and guidelines

Few studies are available to inform duration of intravenous antibiotics for children and when it is safe and appropriate to switch to oral antibiotics. We have systematically reviewed antibiotic duration and timing of intravenous to oral switch for 36 paediatric infectious diseases and developed evidence-graded recommendations on the basis of the review, guidelines, and expert consensus. We searched databases and obtained information from references identified and relevant guidelines. All eligible studies were assessed for quality. 4090 articles were identified and 170 studies were included. Evidence relating antibiotic duration to outcomes in children for some infections was supported by meta-analyses or randomised controlled trials; in other infections data were from retrospective series only. Criteria for intravenous to oral switch commonly included defervescence and clinical improvement with or without improvement in laboratory markers. Evidence suggests that intravenous to oral switch can occur earlier than previously recommended for some infections. We have synthesised recommendations for antibiotic duration and intravenous to oral switch to support clinical decision making and prospective research.

Comparing 3 methods of monitoring gentamicin concentrations in patients with febrile neutropenia

Several nomograms and algorithms have been developed to individualize pharmacokinetic monitoring with their own advantages and disadvantages. This study compared 3 pharmacokinetic methods for predicting doses and monitoring of gentamicin in adult patients with febrile neutropenia. A retrospective study of 75 patients with febrile neutropenia was conducted at the Royal Adelaide Hospital, South Australia. Each patient received a course of once-daily gentamicin and had 2 sets of paired gentamicin serum concentrations. Pharmacokinetic parameters and ensuing doses were compared using 3 pharmacokinetic methods: (1) sequential Bayesian algorithm for gentamicin (SeBA-GEN), (2) Sawchuk-Zaske, and (3) Therapeutic Guidelines: Antibiotic Dose Adjustment Nomogram. The initial median (range) dose of gentamicin administered was 400 (240-640) mg. SeBA-GEN and Sawchuk-Zaske methods recommended similar subsequent gentamicin dose adjustments of 400 (280-640) mg and 400 (280-640) mg, respectively, whereas the Therapeutic Guidelines recommended an increase to 1390 (210-6240) mg. For the Therapeutic Guidelines, 64% of the patients had measured serum gentamicin concentrations that were below the minimum line of the nomogram for the first set of concentrations with only 32% of these patients having an area under the curve value of <70 mg h/L as calculated by SeBA-GEN. The SeBA-GEN method showed a statistically significant increase (68%-77%) in patients attaining the target concentrations of maximum concentration (Cmax) 15-25 mg/L compared with the Sawchuk-Zaske method (72%-65%, P > 0.05). SeBA-GEN also demonstrated greater precision in predicting the area under the curve, Cmax, and minimum concentration (Cmin) compared with the Sawchuk-Zaske method. In conclusion, as the Bayesian approach, that is, SeBA-GEN demonstrated greater precision and more patients were attaining the target concentrations, it is therefore the preferred method for gentamicin monitoring in patients with febrile neutropenia.

Antimicrobial Stewardship Activities: A Survey of Queensland Hospitals

OBJECTIVE In 2011, the Australian Commission on Safety and Quality in Health Care (ACSQHC) recommended that all hospitals in Australia must have an Antimicrobial Stewardship (AMS) program by 2013. Nevertheless, little is known about current AMS activities. This study aimed to determine the AMS activities currently undertaken, and to identify gaps, barriers to implementation and opportunities for improvement in Queensland hospitals. METHODS The AMS activities of 26 facilities from 15 hospital and health services in Queensland were surveyed during June 2012 to address strategies for effective AMS: implementing clinical guidelines, formulary restriction, reviewing antimicrobial prescribing, auditing antimicrobial use and selective reporting of susceptibility results. RESULTS The response rate was 62%. Nineteen percent had an AMS team (a dedicated multidisciplinary team consisting of a medically trained staff member and a pharmacist). All facilities had access to an electronic version of Therapeutic Guidelines: Antibiotic, with a further 50% developing local guidelines for antimicrobials. One-third of facilities had additional restrictions. Eighty-eight percent had advice for restricted antimicrobials from in-house infectious disease physicians or clinical microbiologists. Antimicrobials were monitored with feedback given to prescribers at point of care by 76% of facilities. Deficiencies reported as barriers to establishing AMS programs included: pharmacy resources, financial support by hospital management, and training and education in antimicrobial use. CONCLUSIONS Several areas for improvement were identified: reviewing antimicrobial prescribing with feedback to the prescriber, auditing, and training and education in antimicrobial use. There also appears to be a lack of resources to support AMS programs in some facilities. WHAT IS KNOWN ABOUT THE TOPIC?: The ACSQHC has recommended that all hospitals implement an AMS program by 2013 as a requirement of Standard 3 (Preventing and Controlling Healthcare-Associated Infections) of the National Safety and Quality Health Service Standards. The intent of AMS is to ensure appropriate prescribing of antimicrobials as part of the broader systems within a health service organisation to prevent and manage healthcare-associated infections, and improve patient safety and quality of care. This criterion also aligns closely with Standard 4: Medication Safety. Despite this recommendation, little is known about what AMS activities are undertaken in these facilities and what additional resources would be required in order to meet these national standards. WHAT DOES THE PAPER ADD?: This is the first survey that has been conducted of public hospital and health services in Queensland, a large decentralised state in Australia. This paper describes what AMS activities are currently being undertaken, identifies practice gaps, barriers to implementation and opportunities for improvement in Queensland hospitals. WHAT ARE THE IMPLICATIONS FOR PRACTITIONERS?: Several areas for improvement such as reviewing antimicrobial prescribing with feedback to the prescriber, auditing, and training and education in antimicrobial use have been identified. In addition, there appears to be a lack of resources to support AMS programs in some facilities.

Hematological reference ranges in black very low birth weight infants

This study compared hematological reference ranges in black very low birth weight infants to previously published values established predominantly on white subjects. Ninety-four healthy, black, premature babies with a birth weight of 800 to 1500 g at 2-7 days of age were enrolled as part of a study comparing blood transfusions and high- versus low-dose recombinant erythropoietin in anaemia of prematurity. Peripheral venous blood was collected for a full bloodcount and differential, fetal hemoglobin and erythropoietin levels. The hematological parameters observed in black very low birth weight neonates are similar to previously published reference ranges, except that lower limits of normal were observed for hemoglobin and the red cell indices.

Insulin Infusions in Extremely Low Birth Weight Infants

To the Editor. We read with interest the article by Fuloria et al on insulin infusions in extremely low birth weight (ELBW) infants.1The authors concluded that priming the tubing with a higher concentration of insulin (5 U/mL) before the initiation of a standard insulin infusion therapy should accelerate the achievement of steady-state insulin delivery and correction of hyperglycemia in ELBW.1 This approach would require two insulin concentrations for the routine preparation of these infusions. In our view, this increases the likelihood of errors, especially during shifts when less experienced personnel are present in the NICU. To combat this problem and minimize the loss of insulin in the infusion system, we have, until recently, added serum albumin to the insulin infusion solutions. However, shortages and costs of albumin have led us to retrospectively compare the effectiveness of insulin infusions in ELBW infants with and without albumin. The albumin insulin solutions had 10 mL of the 5% albumin added to the solution, …

Australia-wide Point Prevalence Survey of Antimicrobial Prescribing in Neonatal Units: How Much and How Good?

Background: There is increasing recognition of the threat to neonatal patients from antibiotic resistance. There are limited data on antimicrobial prescribing practices for hospitalized neonates. We aimed to describe antimicrobial use in hospitalized Australian neonatal patients, and to determine its appropriateness. Methods: Multicentre single-day hospital-wide point prevalence survey in 2012, in conjunction with the Antimicrobial Resistance and Prescribing in European Children study. The appropriateness of antimicrobial prescriptions was also assessed. All patients admitted at 8 am on the survey day, in 6 neonatal units in tertiary children’s hospitals across 5 states, were included in an analysis of the quantity and quality of all antimicrobial prescriptions. Results: The point prevalence survey included 6 neonatal units and 236 patients. Of 109 patients (46%) receiving at least 1 antimicrobial, 66 (61%) were being treated for infection, with sepsis the most common indication. There were 216 antimicrobial prescriptions, 134 (62%) for treatment of infection and 82 (38%) for prophylaxis, mostly oral nystatin. Only 15 prescriptions were for targeted as opposed to empirical treatment. Penicillin and gentamicin were the most commonly prescribed antibiotics, with vancomycin third most common. Half of all treated patients were receiving combination antimicrobial therapy. There was marked variation in vancomycin and gentamicin dosing. Overall, few prescriptions (4%) were deemed inappropriate. Conclusion: This is the first Australia-wide point prevalence survey of neonatal antimicrobial prescribing in tertiary children’s hospitals. The findings highlight positive practices and potential targets for quality improvement.

Australia-wide point prevalence survey of the use and appropriateness of antimicrobial prescribing for children in hospital.

Objectives: To describe antimicrobial use in hospitalised Australian children and to analyse the appropriateness of this antimicrobial use.