Assessment of the practical impact of adjusting beta-lactam dosages based on therapeutic drug monitoring in critically ill adult patients: a systematic review and meta-analysis of randomized clinical trials and observational studies

An estimated 70% of critically ill patients receive antibiotics, most frequently beta-lactams. The pharmacokinetic properties of these substances in this patient population are poorly predictable. Therapeutic drug monitoring (TDM) is helpful in making personalized decisions in this field, but its overall impact as a clinical decision-supporting tool is debated. We aimed to evaluate the clinical implications of adjusting beta-lactam dosages based on TDM in the critically ill population by performing a systematic review and meta-analysis of available investigations. Randomized controlled trials and observational studies were retrieved by searching three major databases. The intervention group received TDM-guided beta-lactam treatment, that is, at least one dose reconsideration based on the result of the measurement of drug concentrations, while TDM-unadjusted dosing was employed in the comparison group. The outcomes were evaluated using forest plots with random-effects modeling and subgroup analysis. Eight eligible studies were identified, including 1044 patients in total. TDM-guided beta-lactam treatment was associated with improved clinical cure from infection [odds ratio (OR): 2.22 (95% confidence interval (CI): 1.78-2.76)] and microbiological eradication [OR: 1.72 (CI: 1.05-2.80)], as well as a lower probability of treatment failure [OR: 0.47 (CI: 0.36-0.62)], but the heterogeneity of studies was remarkably high, especially in terms of mortality (70%). The risk of bias was moderate. While the TDM-guided administration of beta-lactams to critically ill patients has a favorable impact, standardized study designs and larger sample sizes are required for developing evidence-based protocols in this field.

Draft genome sequence data of the multidrug-resistant bacterium Staphylococcus haemolyticus 010503B isolated from an aerosol sample in a hospital waiting area in Thailand

Staphylococcus haemolyticus 010503B is a multidrug-resistant bacterium isolated from an outpatient clinic in a hospital waiting area in Thailand. Here we present the draft genome sequence of S. haemolyticus 010503B. The paired-end reads were generated on the Illumina NextSeq 550 sequencer using genomic DNA from the pure culture of S. haemolyticus 010503B. The draft genome consisted of 114 contigs with a total size of 2,457,654 base pairs, an N50 of 57,312 base pairs and a GC content of 32.60%. The dDDH between 010503B and Staphylococcus haemolyticus SM 131T was 91.9%, identifying the strain as Staphylococcus haemolyticus. The data presented holds promise for bacterial classification, comparative genomics, analysing antimicrobial resistance comprehensively, and assessing bacterial virulence factors of S. haemolyticus. The draft genome sequence data has been deposited at NCBI under Bioproject accession number PRJNA550309.

Structural and kinetic analysis of the monofunctional Staphylococcus aureus PBP1

Staphylococcus aureus, an ESKAPE pathogen, is a major clinical concern due to its pathogenicity and manifold antimicrobial resistance mechanisms. The commonly used β-lactam antibiotics target bacterial penicillin-binding proteins (PBPs) and inhibit crosslinking of peptidoglycan strands that comprise the bacterial cell wall mesh, initiating a cascade of effects leading to bacterial cell death. S. aureus PBP1 is involved in synthesis of the bacterial cell wall during division and its presence is essential for survival of both antibiotic susceptible and resistant S. aureus strains. Here, we present X-ray crystallographic data for S. aureus PBP1 in its apo form as well as acyl-enzyme structures with distinct classes of β-lactam antibiotics representing the penicillins, carbapenems, and cephalosporins, respectively: oxacillin, ertapenem and cephalexin. Our structural data suggest that the PBP1 active site is readily accessible for substrate, with little conformational change in key structural elements required for its covalent acylation of β-lactam inhibitors. Stopped-flow kinetic analysis and gel-based competition assays support the structural observations, with even the weakest performing β-lactams still having comparatively high acylation rates and affinities for PBP1. Our structural and kinetic analysis sheds insight into the ligand-PBP interactions that drive antibiotic efficacy against these historically useful antimicrobial targets and expands on current knowledge for future drug design and treatment of S. aureus infections.

Continuous infusion of beta-lactam antibiotics in pediatric intensive care unit: A monocenter before/after implementation study

CONTEXT

Beta-lactam continuous infusion (CI) is currently recommended in adult intensive care units to achieve target concentrations. In pediatric intensive care (PICU), few studies suggest the value of Beta-lactam CI to achieve target concentration. Our objective was to analyze the impact of Beta-lactam CI protocolization on the achievement of target concentration in PICU patients.

MATERIAL AND METHODS

We conducted a single-center retrospective study in patients with beta-lactam treatment for more than 2 days and at least one sample for therapeutic drug monitoring (TDM). From January 2018 to February 2022 (period 1, P1), BL were administered as an intermittent infusion with TDM upon request. From February to September 2022 (period 2, P2), Beta-lactam CI with TDM at day one was protocolized. The primary endpoint concerned achieving fT>4× Minimum Inhibitory Concentration = 100%.

RESULTS

In P1, 214 assays involved 103 patients; in P2, 199 assays involved 72 patients. Target concentration achievement was more frequent in P2 (P2 = 73.7% vs. P1 = 29.1%; p < 0.001). At day 5/6 after Beta-lactam initiation, c-reactive protein concentrations were P1 = 84.9 ± 79.2 mg/L; P2 = 53.7±49.8 mg/L (p < 0.05). In the multivariable logistic regression model: P2, BSA, and albumin were positively associated with target achievement; urea, and male sex were negatively associated with target achievement. The daily average cost of beta-lactam vial consumption per child was: P1 = 5.04 ± 2.6 € vs. P2 = 3.21 ± 2.7 € (p-value < 0.001). The daily average reconstitution time of Beta-lactam syringes per child was: P1 = 23.5 ± 8.7 min, P2 = 13.9 ± 9.2 min (p-value < 0.001).

CONCLUSION

Protocolization of Beta-lactam continuous infusion was associated with more frequent target concentration achievements in PICU. This implementation could be cost-effective and nurse time-saving.

Extended infusion of β-lactams significantly reduces mortality and enhances microbiological eradication in paediatric patients: a systematic review and meta-analysis

Background

Paediatric patients are often exposed to subtherapeutic levels or treatment failure of β-lactams, and prolonged infusion may be beneficial. We aimed to investigate the efficacy and safety of extended infusion (EI; defined as ≥3 h) or continuous infusion vs. short, intermittent infusion (SI; defined as ≤60 min) of β-lactams in patients <21 years of age.

Methods

A systematic review and meta-analysis was conducted to compare EI and continuous infusion with SI of β-lactams in children. A systematic search was performed in MEDLINE (via PubMed), Embase, CENTRAL, and Scopus databases for randomised controlled trials (RCTs) and observational studies published from database inception up to August 22, 2023. Any comparative study concerned with mortality, clinical efficacy, adverse events, or plasma concentrations of β-lactams for any infection was eligible. Case reports, case series, and patients aged >21 years were excluded. Odds ratios (OR) and median differences with 95% confidence intervals (CI) were calculated using a random-effects model. Risk of bias (ROB) was assessed using ROB2 and ROBINS-I tools. The protocol was registered with PROSPERO, CRD42022375397.

Findings

In total, 19,980 articles were screened, out of which 19 studies (4195 patients) were included in the meta-analysis. EI administration was associated with a significantly lower all-cause mortality in both RCTs and non-RCTs [OR 0.74; CI 0.55-0.99; I2 = 0%; CI 0-58%]. Early microbiological eradication was higher with EI [OR 3.18; CI 2.24-4.51; I2 = 0%; CI 0-90%], but the clinical cure did not differ significantly between the two groups [OR 1.20; CI 0.17-8.71; I2 = 79%; CI 32-93%]. Achieving the optimal plasma level (50-100% fT > MIC) appeared favourable in the EI group compared to the SI. No significant differences were observed in the adverse events. The overall ROB was high because of the small sample sizes and clinically heterogeneous populations.

Interpretation

Our findings suggest that extended infusion of β-lactams was associated with lower mortality and increased microbiological eradication and was considered safe compared to short-term infusion.

Funding

None.

Impact of azithromycin, doxycycline and redox-active small molecules on amoxicillin-induced Chlamydia pneumoniae persistence

Amoxicillin is recommended as primary treatment for community-acquired bacterial pneumonia (CABP). 5-10% of CABP cases are caused by Chlamydia pneumoniae, an obligate intracellular bacterium which responds to beta-lactam antibiotics by converting to a persistent phenotype. To support rational pharmacotherapy of C. pneumoniae infections, we investigated how clinically relevant concentrations of azithromycin and doxycycline affect amoxicillin induced C. pneumoniae persistence. Given the known role of redox state alterations in the action of bactericidal antibiotics and widespread use of redox-active dietary supplements when experiencing respiratory symptoms, we also studied how redox active compounds affect the studied antibiotic treatments. Our data demonstrate that clinically applied amoxicillin concentrations (10 and 25 mg/l) fail to eradicate C. pneumoniae infection in respiratory epithelial cells. Transmission electron microscopy (TEM) of amoxicillin-treated C. pneumoniae infected cells reveal aberrant bacterial morphology characteristic of chlamydial stress response. Amoxicillin was also found to significantly limit the antichlamydial effect of azithromycin or doxycycline. However, based on quantitative culture and quantitative PCR data, azithromycin was superior to doxycycline in C. pneumoniae eradication either as monotherapy or in combination with amoxicillin. Amoxicillin was also found to decrease respiratory epithelial cell glutathione (GSH) levels, whereas redox-active dibenzocyclooctadiene lignans increased C. pneumoniae load in amoxicillin-treated cultures up to two-fold. These data highlight the impact of relative administration time on the efficacy of antichlamydial antibiotics and indicate unfavorable interactions between amoxicillin and redox-active small molecules.

Meropenem allergy testing performed at the bedside of hospitalized patients labelled with a penicillin allergy

BACKGROUND

Meropenem is a widely prescribed beta-lactam for hospitalized patients. There are few data on meropenem allergy assessments in inpatients with a reported history of penicillin allergy who require a treatment with meropenem. This can lead to the use of less effective second-line antibiotics that may increase antibiotic resistances. We aimed to evaluate the clinical outcomes of a meropenem allergy assessment in admitted patients with a reported history of penicillin allergy that required meropenem for the treatment of an acute infection.

METHODS

A retrospective analysis was performed on 182 inpatients labelled with a penicillin-allergy who received meropenem after an allergy assessment. The allergy study was performed bedside if meropenem was required urgently. The study included skin prick tests (SPTs) followed by an intradermal skin test (IDT) to meropenem, and a meropenem drug challenge test (DCT). If a non-immediate reaction to a beta-lactam was suspected, it was initiated with patch tests.

RESULTS

The median age of the patients was 59.7 years (range 28-95) and 80 (44%) were women. A total of 196 sets of diagnostic workups were performed, with 189 (96.4%) of them being tolerated. Only two patients had a positive meropenem IV DCT, both presenting a non-severe cutaneous reaction that completely resolved after treatment.

CONCLUSIONS

This study evidenced that a bedside meropenem allergy assessment of hospitalized patients labelled with a 'penicillin allergy' who require a broad-spectrum antibiotic for empiric coverage is a safe and effective procedure, avoiding the use of second-line antimicrobial agents.

Diagnosis and selection of alternative antibiotics in beta-lactams hypersensitivity reactions: Current recommendations and challenges

Beta-lactam (BLM) antibiotics, including amino-penicillin and cephalosporins, are typically the first-choice treatment for bacterial infections. However, adverse reactions to these antibiotics are frequently reported, causing non-allergist physicians to select alternative broad-spectrum antibiotics that can have harmful consequences. Patients with unclear histories of hypersensitivity reactions to BLMs should undergo an allergy workup to establish a firm diagnosis, particularly when different drugs are prescribed simultaneously. However, finding the safest, most precise, and cost-effective methods for confirming BLMs hypersensitivity and selecting the most appropriate alternative BLM is uncertain, particularly in severe delayed reactions. This review aims to provide data and recommendations on the availability and validity of skin tests (STs), drug provocation test (DPT) protocols, based on the latest published literature and guideline. To make the process more practical, we focused on cross-reactivity between BLMs and diagnostic tests. There are two main novel aspects of this document: 1) For T-cell-mediated reactions, patient stratification into high, moderate, and low-risk groups based on the mortality and morbidity of adverse drug reactions. 2) For IgE-mediated reactions, stratification of individuals with isolated limited urticarial without anaphylaxis in a low-risk group and removal of the extensive limitation.

Respiratory fluoroquinolone monotherapy vs. β-lactam plus macrolide combination therapy for hospitalized adults with community-acquired pneumonia: A systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Guidelines recommend respiratory fluoroquinolone monotherapy or β-lactam plus macrolide combination therapy as first-line options for hospitalized adults with mild-to-moderate community-acquired pneumonia (CAP). Efficacy of these regimens has not been adequately evaluated.

METHODS

A systematic review of randomized controlled trials (RCTs) comparing respiratory fluoroquinolone monotherapy and β-lactam plus macrolide combination therapy in hospitalised adults with CAP was performed. A meta-analysis was performed using a random effects model. The primary outcome was clinical cure rate. Quality of evidence (QoE) was evaluated using GRADE methodology.

RESULTS

A total of 4140 participants in 18 RCTs were included. Levofloxacin (11 trials) or moxifloxacin (6 trials) were the predominant respiratory fluoroquinolones evaluated, and the β-lactam plus macrolide group used ceftriaxone plus a macrolide (10 trials), cefuroxime plus azithromycin (5 trials), and amoxicillin/clavulanate plus a macrolide (2 trials). Patients receiving respiratory fluoroquinolone monotherapy had a significantly higher clinical cure rate (86.5% vs. 81.5%; odds ratio [OR] 1.47; 95% confidence interval [95% CI: 1.17-1.83]; P = 0.0008; I2 = 0%; 17 RCTs; moderate QoE) and microbiological eradication rate (86.0% vs. 81.0%; OR 1.51 [95% CI: 1.00-2.26]; P = 0.05; I2 = 0%; 15 RCTs; moderate QoE) than patients receiving β-lactam plus macrolide combination therapy. All-cause mortality (7.2% vs. 7.7%; OR 0.88 [95% CI: 0.67-1.17]; I2 = 0%; low QoE) and adverse events (24.8% vs. 28.1%; OR 0.87 [95% CI: 0.69-1.09]; I2 = 0%; low QoE] were similar in the two groups.

CONCLUSION

Respiratory fluoroquinolone monotherapy demonstrated an advantage in clinical cure and microbiological eradication; however, it did not impact mortality.

Quarter-wise proportion and beta-lactam resistance rate of bovine mastitis associated- Staphylococcus aureus among infectious episodes in Ethiopia: Systematic review and meta-Analysis

Background

Bovine mastitis, a condition with multifactorial etiology, imposes a significant economic burden on the dairy sector in Ethiopia, with Staphylococcus aureus (S. aureus) being one of the leading etiologic agents. The acquisition of a compiled source of information concerning S. aureus is imperative in order to enhance the control and prevention strategies, as well as to facilitate the successful implementation of the national action plan aimed at curbing antimicrobial resistance by the year 2025. Thus, the primary objective of this meta-analysis was to comprehensively summarize the estimates of the proportion and beta-lactam resistance profile of S. aureus in bovine mastitis in Ethiopia.

Methods

electronic bibliographic data such as PubMed, Web of Science, HINARI, Google Scholar, and other databases were used to search articles and quality assessment was performed using the AMSTAR-2. The pooled proportion, the rate of beta-lactam resistance, and a 95% confidence interval were calculated with a random effects model using STATA 17 statistical software. Funnel plots, and Eggers were used to assess publication bias.

Results

Twenty-six (26) cross-sectional studies were included in this meta-analysis. The overall pooled proportion of S.aureus was 35% (95% CI: 0.31 to 0.41). Considerable heterogeneity was observed in the included studies (I² = 90.75%; P < 0.01). The subgroup analysis of the study region showed significant differences. The highest estimated regional pooled proportion of bovine mastitis-associated S.aureus was 40% in the Amhara and Tigray regions. Funnel plot and Eggers results showed no statistically significant publication bias (Eggers test: p = 0.5656) in estimating the proportion of S.aureus infections in association with bovine mastitis. A total of 14 articles were included to estimate beta-lactam antimicrobial resistance. The estimated pooled beta-lactam antimicrobial resistance rate of S.aureus was resistance to penicillin at 75%, followed by amoxicillin at 67%, ampicillin at 50% and cephalosporin at 57% were evaluated in the treatment of S. aureus. Therefore, the present meta-analysis has revealed that the prevalence of bovine-associated Staphylococcus aureus and its resistance to beta-lactam antibiotics are alarmingly high in the region of Ethiopia. This further emphasizes the vital necessity of implementing effective preventive measures to reduce the incidence and spread of this pathogen across the entire nation.

The Dutch Working Party on Antibiotic Policy (SWAB) guideline for the approach to suspected antibiotic allergy

OBJECTIVES

Prudent handling of reported antibiotic allergy is an important aspect of antibiotic stewardship. The Dutch Working Party on Antibiotic Policy (SWAB) constituted a multidisciplinary expert committee to provide evidence-based recommendations for bedside decision making in antibiotic therapy in patients that report an antibiotic allergy.

METHODS

The guideline committee generated 12 key questions, most of which were population, intervention, comparison and outcome (PICO) questions relevant for both children and adults with suspected antibiotic allergy. For each question a systematic literature search was performed and reviewed for the best available evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Quality of evidence was graded from very low to high and recommendations were formulated in structured discussions as strong or weak.

RESULTS

Sixty recommendations were provided for suspected allergy to beta-lactam antibiotics (BLA) and non-beta-lactam antibiotics (NBLA). Due to the absence of randomized controlled trials in this field, the underlying evidence was predominantly graded as low or very low. Available data supports that a detailed allergy history should always be performed and critically appraised. When cross-allergy between BLA groups is not to be expected due to absence of molecular similarity of the side chains, the patient can be safely exposed to the alternative BLA. An exception to this rule are severe delayed type reactions, in which reexposure to a BLA should only be considered after consultation of a multidisciplinary team.

CONCLUSIONS

Accumulated scientific data now supports a more liberal approach that better balances benefits of treatment with first choice and usually smaller spectrum antibiotics with appropriate avoidance of antibiotics in case of a truly high risk of a (severe) allergic reaction. In the Netherlands, a formal guideline was developed that provides recommendations for the approach towards suspected allergy to BLA and frequently used NBLA, thereby strongly supporting antimicrobial stewardship.

Therapeutic drug monitoring in cystic fibrosis and associations with pulmonary exacerbations and lung function

BACKGROUND

Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy have resulted in longer life expectancies, yet pulmonary exacerbations remain a leading cause of morbidity. Intravenous antibiotics is the mainstay treatment, however achieving adequate concentrations remains challenging. The effect of therapeutic drug monitoring (TDM) of beta-lactams on exacerbations and lung function has not been studied.

METHODS

Patient demographics, antibiotic regimens, forced expiratory volume 1 second (FEV1), and exacerbation history was obtained from 32 patients with cystic fibrosis admitted for exacerbations. All patients were colonized with Pseudomonas aeruginosa, received CFTR therapy for at least one year, and had 3-month interval follow ups. Plasma concentrations, FEV1, and exacerbation history was obtained before and after therapeutic drug monitoring. This included peak and trough plasma concentrations of piperacillin-tazobactam and cefepime using liquid chromatography with mass spectrometry. T-test and Mann-Whitney U test were used to compare medians/means of FEV1 and pulmonary exacerbations pre and post-TDM as well as free trough-to-minimum inhibitory concentration ratio (fC_min/MIC) ≥1 and ≥ 4.

RESULTS

TDM was associated with decreased exacerbations/year from 1.91 to 1.31 (p = 0.04) and among the cohort with >/ = 2 exacerbations per year, there was a longer exacerbation free interval after TDM (196.2 vs 103.7 days, p = 0.02). The decline in FEV1% predicted after therapeutic drug monitoring to the first exacerbation was -4.9 compared to -9.7 prior (p = 0.03).

CONCLUSIONS

TDM for cystic fibrosis pulmonary exacerbations results in decreased pulmonary exacerbations, longer intervals to pulmonary exacerbation, and lower decline in FEV1% predicted.

Risk Factors of Challenge-Proven Beta-Lactam Allergy in Children with Immediate and Non-Immediate Mild Cutaneous Reactions

INTRODUCTION

Beta-lactam (BL) antibiotics are the most often involved drugs in allergic reactions. Mild cutaneous reactions such as maculopapular exanthema or urticaria are the most common presenting complaints of BL allergy in the pediatric population. However, it can be challenging to distinguish BL-induced allergy from reactions due to infections or other reasons. In this study, we aimed to determine the clinical characteristics and potential risk factors of true BL allergy in children with suspected mild cutaneous reactions to BLs.

METHODS

We evaluated children who were admitted to our pediatric allergy clinic with suspected BL allergy in between January 2015 and March 2020. Patients with a history suggestive of immediate and non-immediate mild cutaneous reactions were included in the study. The oral challenge test (OCT) with the culprit drug was performed on all patients to confirm the diagnosis.

RESULTS

Two hundred fourteen (119 male and 95 female) patients with a median age of 4.9 years were evaluated. BL allergy was confirmed in 10.7% (23) of the patients, according to the OCT results. Most of the proven allergic reactions were of the immediate type (73.9%), and urticaria was the most common presenting complaint (60.8%) in proven BL-allergic patients. The negative predictive value of penicillin-G skin testing was 89.7% for immediate-type penicillin allergy and 93.4% for non-immediate reactions. Also, positive predictive value of penicillin-G skin testing was 50% for immediate and 25% for non-immediate reactions. In the multivariate logistic regression analysis, a history of proven drug allergy (Exp (B): 7.76, 95% CI: 1.88-31.97, p = 0.005) was found to be the risk for BL allergy.

CONCLUSION

This study highlighted that OCTs should be performed to confirm the diagnosis in patients suspected of immediate and non-immediate mild cutaneous reactions to BLs and remove the overestimated "BL allergy" label. In these patients, a history of proven drug allergy might be a risk factor for true BL allergy.

Impact of renal replacement therapy strategy on beta-lactam plasma concentrations: the BETAKIKI study-an ancillary study of a randomized controlled trial

BACKGROUND

Sepsis prognosis correlates with antibiotic adequacy at the early phase. This adequacy is dependent on antibacterial spectrum, bacterial resistance profile and antibiotic dosage. Optimal efficacy of beta-lactams mandates concentrations above the minimal inhibitory concentration (MIC) of the targeted bacteria for the longest time possible over the day. Septic acute kidney injury (AKI) is the most common AKI syndrome in ICU and often mandates renal replacement therapy (RRT) initiation. Both severe AKI and RRT may increase outside target antibiotic concentrations and ultimately alter patient's prognosis.

PATIENTS AND METHODS

This is a secondary analysis of a randomized controlled trial that compared an early RRT initiation strategy with a delayed one in 620 critically ill patients undergoing severe AKI (defined by KDIGO 3). We compared beta-lactam trough concentrations between the two RRT initiation strategies. The primary outcome was the proportion of patients with sufficient trough plasma concentration of beta-lactams defined by trough concentration above 4 times the MIC. We hypothesized that early initiation of RRT could be associated with an insufficient antibiotic plasma trough concentration compared to patients allocated to the delayed strategy.

RESULTS

One hundred and twelve patients were included: 53 in the early group and 59 in the delayed group. Eighty-three patients (74%) had septic shock on inclusion. Trough beta-lactam plasma concentration was above 4 times the MIC breakpoint in 80.4% (n = 90) of patients of the whole population, without differences between the early and the delayed groups (79.2% vs. 81.4%, respectively, p = 0.78). On multivariate analysis, the presence of septic shock and a higher mean arterial pressure were significantly associated with a greater probability of adequate antibiotic trough concentration [OR 3.95 (1.14;13.64), p = 0.029 and OR 1.05 (1.01;1.10), p = 0.013, respectively). Evolution of procalcitonin level and catecholamine-free days as well as mortality did not differ whether beta-lactam trough concentration was above 4 times the MIC or not.

CONCLUSIONS

In this secondary analysis of a randomized controlled trial, renal replacement therapy initiation strategy did not significantly influence plasma trough concentrations of beta-lactams in ICU patients with severe AKI. Presence of septic shock on inclusion was the main variable associated with a sufficient beta-lactam concentration.

TRIAL REGISTRATION

The AKIKI trial was registered on ClinicalTrials.gov (Identifier: NCT01932190) before the inclusion of the first patient.

Evaluation of pre-treated healthcare wastes during COVID-19 pandemic reveals pathogenic microbiota, antibiotics residues, and antibiotic resistance genes against beta-lactams

The disposal of healthcare waste without prior elimination of pathogens and hazardous contaminants has negative effects on the environment and public health. This study aimed to profile the complete microbial community and correlate it with the antibiotic compounds identified in microwave pre-treated healthcare wastes collected from three different waste operators in Peninsular Malaysia. The bacterial and fungal compositions were determined via amplicon sequencing by targeting the full-length 16S rRNA gene and partial 18S with full-length ITS1-ITS2 regions, respectively. The antibiotic compounds were characterized using high-throughput spectrometry. There was significant variation in bacterial and fungal composition in three groups of samples, with alpha- (p-value = 0.04) and beta-diversity (p-values <0.006 and < 0.002), respectively. FC samples were found to acquire more pathogenic microorganisms than FA and FV samples. Paenibacillus and unclassified Bacilli genera were shared among three groups of samples, meanwhile, antibiotic-resistant bacteria Proteus mirabilis, Enterococcus faecium, and Enterococcus faecalis were found in modest quantities. A total of 19 antibiotic compounds were discovered and linked with the microbial abundance detected in the healthcare waste samples. The principal component analysis demonstrated a positive antibiotic-bacteria correlation for genera Pseudomonas, Aerococcus, Comamonas, and Vagococcus, while the other bacteria were negatively linked with antibiotics. Nevertheless, deep bioinformatic analysis confirmed the presence of bla_TEM-1 and penP which are associated with the production of class A beta-lactamase and beta-lactam resistance pathways. Microorganisms and contaminants, which serve as putative indicators in healthcare waste treatment evaluation revealed the ineffectiveness of microbial inactivation using the microwave sterilization method. Our findings suggested that the occurrence of clinically relevant microorganisms, antibiotic contaminants, and associated antibiotic resistance genes (ARGs) represent environmental and human health hazards when released into landfills via ARGs transmission.

Penicillin Allergy Evaluation and Health Equity: A Call to Action

Allergists have been at the forefront of addressing the burden of unverified penicillin allergy labels. Coordinated national efforts with infectious diseases, antimicrobial stewardship experts, and pharmacy societies to advocate for formal evaluation of patient-reported penicillin allergy have resulted in improvements in delabeling efforts. Given the poorer health outcomes associated with the penicillin allergy label and the potential health benefits that can be gained with delabeling, improving access to penicillin allergy evaluation is of the utmost importance. Health disparities are widely recognized to impact all aspects of health care, and multilevel interventions at the patient, clinician, and systems level are required to ensure equitable care delivery. Structural racism underpins many social determinants of health and is a key driver of racial and ethnic health disparities. In this Rostrum, we use a conceptual framework from the 2015 National Academy of Medicine report Improving Diagnosis in Health Care to explore how inequities are related to the evaluation of penicillin allergy. We use the National Institute on Minority Health and Health Disparities Strategies to Advance Health Disparities to elucidate areas of important study. Building upon existing efforts to address disparities in Allergy/Immunology, we highlight the urgent importance of understanding and eliminating health disparities in penicillin allergy evaluation and delabeling.

Use of clindamycin as an alternative antibiotic prophylaxis

BACKGROUND

Clindamycin serves as an alternative surgical prophylactic antibiotic in patients with penicillin (PCN) or cephalosporin allergy labels. In the previous reports, the use of clindamycin was associated with higher incidences of surgical site infections (SSIs). We aimed to determine the characteristics of PCN or cephalosporin allergic reactions to stratify patient's risk and indicate subsequent management; leading to de-labeling of PCN or cephalosporin allergy.

METHODS

We conducted a prospective cohort study of patients receiving clindamycin as surgical antibiotic prophylaxis from September 2021 to March 2022. Data were collected from electronic medical records; included demographic data, antibiotic allergy labels, allergic reaction, and allergy testing.

RESULTS

Clindamycin was administered in 445 patients who underwent 451 operations. Among these patients, 53.0% (n = 236) were female with a median age of 15 years (range; 0.5-57.0 years). PCN and cephalosporin allergies were labelled in 83.8% (n = 373) and 25.6% (n = 114) patients, respectively; 11.4% (n = 51) of patients were allergic to both classes of the antibiotics. There were 191 (51.2%) and 73 (64.0%) possible hypersensitivity reactions (HSRs) in PCN and cephalosporin groups, respectively. The most common reactions were rash (PCN: n = 99, 26.5%; cephalosporin: n = 35, 30.7%), and hives (PCN: n = 71, 19.0%; cephalosporin: n = 24, 21.1%). Severe reactions included angioedema (PCN: n = 7, 1.9%; cephalosporin: n = 5, 4.4%), anaphylaxis (PCN: n = 8, 2.1%; cephalosporin: n = 7, 6.1%), bronchospasm (cephalosporin: n = 1, 0.9%), airway involvement (PCN: n = 1, 0.3%; cephalosporin: n = 1, 0.9%), serum sickness (PCN: n = 1, 0.3%), blisters (PCN: n = 1, 0.3%), and drug reaction with eosinophilia and systemic symptoms (DRESS) (PCN: n = 1, 0.3%). Low-risk history of allergy included gastrointestinal side effects (PCN: n = 9, 2.4%; cephalosporin: n = 3, 2.7%), positive family history (PCN: n = 7, 1.9%; cephalosporin: n = 1, 0.9%), and remote history of allergy (PCN: n = 2, 0.5%). There were 201 (53.9%) and 53 (46.5%) unknown reactions in PCN and cephalosporin groups, respectively. In the overall cohort, 3 patients (0.7%) were skin tested for drug allergy (PCN: n = 2, 0.5%; cephalosporin: n = 2, 1.8%).

CONCLUSION

Clindamycin was largely administered in patients with non-severe HSRs, low-risk history or unknown reactions to PCN or cephalosporin, whom cefazolin could have been administered safely. Obtaining a detailed history of antibiotic allergy, allergy testing and/or direct oral challenge can de-label unsubstantiated PCN or cephalosporin allergy and ultimately reduce the incidence of SSIs by optimizing the rate of more effective antibiotic administration.

Impact of therapeutic drug monitoring of antibiotics in the management of infective endocarditis

Treatment of infective endocarditis (IE) is based on high doses of antibiotics with a prolonged duration. Therapeutic drug monitoring (TDM) allows antibiotic prescription optimization and leads to a personalized medicine, but no study evaluates its interest in the management of IE. We conducted a retrospective, bicentric, descriptive study, from January 2007 to December 2019. We included patients cared for IE, defined according to Duke's criteria, for whom a TDM was requested. Clinical and microbiological data were collected after patients' charts review. We considered a trough or steady-state concentration target of 20 to 50 mg/L. We included 322 IE episodes, corresponding to 306 patients, with 78.6% (253/326) were considered definite according to Duke's criteria. Native valves were involved in 60.5% (185/306) with aortic valve in 46.6% (150/322) and mitral in 36.3% (117/322). Echocardiography was positive in 76.7% (247/322) of cases. After TDM, a dosage modification was performed in 51.5% (166/322) (decrease in 84.3% (140/166)). After initial dosage, 46.3% (82/177) and 92.8% (52/56) were considered overdosed, when amoxicillin and cloxacillin were used, respectively. The length of hospital stay was higher for patient overdosed (25 days versus 20 days (p = 0.04)), and altered creatinine clearance was associated with overdosage (p = 0.01). Our study suggests that the use of current guidelines probably leads to unnecessarily high concentrations in most patients. TDM benefits predominate in patients with altered renal function, but probably limit adverse effects related to overdosing in most patients.

MIC Discrepancies between Parenteral and Oral Anti-Staphylococcal Beta-Lactams among MSSA

INTRODUCTION

Recent evidence has shown that oral antibiotic therapy is not inferior to IV antibiotic therapy in the treatment of complicated Staphylococcus aureus infections. Therefore, oral antibiotic therapy is now frequently prescribed in clinical practice due to cost benefit, ease of administration, decreased complication rate, and lack of need for IV access. In vitro susceptibility testing for β-lactam oral antibiotics is not routinely performed as the guidelines provided by the Clinical and Laboratory Standards Institute (CLSI) recommend using oxacillin and cefoxitin as surrogate markers. Hence, oral antibiotic susceptibilities for cephalexin and dicloxacillin are not reported and implied based on oxacillin and cefoxitin. The objective of the current study was to determine whether susceptibilities among S. aureus isolates are predictable when comparing commonly used IV and oral beta-lactams.

METHODS

Cefazolin, cephalexin, dicloxacillin, and oxacillin broth microdilution minimum inhibitory concentrations (MICs) were determined for 100 clinical isolates of methicillin-sensitive S. aureus by broth microdilution following CLSI guidelines.

RESULTS

Among these isolates, median MICs for cephalexin were eight-fold higher than cefazolin MICs and median MICs for dicloxacillin were four-fold less than oxacillin MICs. Ten percent of more strains studied had a major or very major error in its susceptibility reporting when cephalexin was compared to its surrogate marker oxacillin.

DISCUSSIONS/CONCLUSIONS

The variations in MICs observed compounded with the dosing and pharmacokinetic differences of oral versus IV β-lactam suggests that establishing breakpoints for oral β-lactam antibiotics is necessary to ensure adequate therapy is selected for the treatment of complex S. aureus infections.

Cefepime population pharmacokinetics and dosing regimen optimization in critically ill children with different renal function

OBJECTIVE

Cefepime is commonly used in pediatric intensive care units (PICUs), where unpredictable variations in the patients' pharmacokinetic (PK) variables may require drug dose adjustments. The objectives of the present study were to build a population PK model for cefepime in critically ill children and to optimize individual initial dosing regimens.

METHODS

Children (aged from 1 month to 18 years; bodyweight >3 kg) receiving cefepime were included. Cefepime total plasma concentrations were measured using high performance liquid chromatography. Data were modelled using non-linear, mixed-effect modeling software, and Monte Carlo simulations were performed with a PK target of 100% fT _{> MIC}.

RESULTS

Fifty-nine patients (median (range) age: 13.5 months (1.1 month-17.6 years)) and 129 cefepime concentration measurements were included. The cefepime concentration data were best fitted by a one-compartment model. The selected covariates were body weight with allometric scaling and estimated glomerular filtration rate on clearance. Mean population values for clearance and volume were 1.21 L.h^-1 and 4.8 L, respectively. According to the simulations, a regimen of 100 mg.kg^-1.day^-1 q12 h over 30 min or 100 mg.kg^-1.day^-1 as a continuous infusion was more likely to achieve the PK target in patients with renal failure and in patients with normal or augmented renal clearance, respectively.

CONCLUSIONS

Appropriate cefepime dosing regimens should take renal function into account. Continuous infusions are required in critically ill children with normal or augmented renal clearance, while intermittent infusions are adequate for children with acute renal failure. Close therapeutic drug monitoring is mandatory, given cefepime's narrow therapeutic window.

The efficacy of pivmecillinam in oral step-down treatment in hospitalised patients with E. coli bacteremic urinary tract infection; a single-arm, uncontrolled treatment study

Background

The role of oral beta-lactam antibiotics in treating febrile urinary tract infections (UTI) is not yet definite. Today, fluoroquinolones together with trimethoprim–sulfamethoxazole (TMP–MTX) are considered standard of care and often the only available evidence-based oral treatment for febrile UTI. This study clarifies the efficacy and safety of pivmecillinam (PIV) used as step-down therapy for bacteremic urinary tract infection (UTI).

Methods

A single-arm, uncontrolled treatment trial was conducted in the period September 2017–March 2020. Candidates for inclusion were men and women suffering from E. coli bacteremia due to UTI and were consecutively included in a Norwegian hospital. Exclusion criteria were among others: other ongoing bacterial infection, septic shock, pyonephrosis/abscess and pregnancy. After 3 days of parenteral antibiotic, the treatment was converted to the study drug; oral PIV 400 mg QID for 1 week. Primary endpoint was a combination of three elements; afebrility, no need for retreatment and improvement in self-reported health status. Test Of Cure (TOC) was 1 week post-treatment. Secondary endpoints included among others microbiological efficacy and CRP value < 30 mg/L.

Results

Of 476 screened subjects, 53 patients were included. Median age was 67 years, 28 (56%) were women. 50 patients were evaluated for per-protocol analysis. 44 of 50 patients (88%) (95% CI [75.7–95.5]) reached the primary endpoint on TOC. 14 of 48 patients (29.2%) had significant growth (> 10³ CFU/mL) of E.coli on TOC. CRP-level was strongly associated to treatment outcome, (OR 0.006 [95% CI 0.00–0.11], p < 0.001).

Conclusions

This trial documents that PIV 400 mg QID given for 1 week following 3 days of parenteral antibiotics, is a suitable treatment option in patients suffering from bacteremic UTI due to E. coli. Randomised clinical trials studying the efficacy of PIV vs standard of care of febrile UTI are warranted.

Trial registration The trial was registered at ClinicalTrials.gov under the identifier: NCT03282006 13/09/2017 and approved by The Regional Committees for Medical Research Ethics South East Norway (2015/2384/REK sør-øst) and the Norwegian Medicines Agency (SLV; reference No 16/06018-09; EudraCT No 2016-000984-18) before initiation

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07463-7.

Ceftazidime dosing in obese patients: is it time for more?

INTRODUCTION

Ceftazidime is used for the treatment of many bacterial infections, including severe P. aeruginosa infections. Like other beta-lactams, inter-individual variability in ceftazidime pharmacokinetics has been described. Due to its related pathophysiological modifications, obesity might influence ceftazidime pharmacokinetics.

AREAS COVERED

The objective of this review is to assess the current state of knowledge about the impact of obesity on ceftazidime treatment. A literature search was conducted on PubMed-MEDLINE (2016-2021) to retrieve pharmacokinetic studies published in English, matching the terms 'ceftazidime' AND 'pharmacokinetics.'

EXPERT OPINION

The impact of obesity on pharmacokinetics is generally poorly known, mainly because obese patients are often excluded from clinical studies. However, the published literature clearly shows that obese patients have significantly lower ceftazidime concentrations. This could be explained by increased volume of distribution and clearance. This low exposure represents a major factor of therapeutic failure, potentially fatal for critically ill patients. While further studies would be useful to better assess the magnitude and understanding of this variability, the use of higher doses of ceftazidime is needed in obese patients. Moreover, therapeutic drug monitoring for dose adaptation is of major interest for these patients, as the efficacy of ceftazidime seems to be directly related to its plasma concentration.

Improvement of the QuEChERS extraction step by matrix-dispersion effect and application on beta-lactams analysis in wastewater sludge by LC-MS/MS

In the last decade, beta-lactams use in veterinary and human medicine increased to represent today about 15% of the overall consumption. Beta-lactams tend to degrade and metabolize in the environment. Therefore, analytical methods must be sensitive enough to quantify low concentrations of the parent molecules and also allow detection of metabolites. This study presents the development of a modified QuEChERS method for the extraction of seven beta-lactams and one degradation product (Amoxicillin, Ampicillin, Cefapirin, Cefoperazone, Cefquinome, Ceftiofur, Cloxacillin, and Amoxicillin-Diketopiperazine) from sewage treatment plant sludge and their analysis by liquid chromatography coupled with tandem mass spectrometry. Before the QuEChERS extraction, a dispersion step of the sample with EDTA-treated sand was optimized and added, allowing to facilitate the exchanges between the matrix and the extraction solvent. Then, to decrease the interferences present in the extract, a fast and efficient pass-through SPE was implemented. The optimized method was validated and showed satisfactory performances, in adequacy with the analysis of beta-lactams in solid environmental matrices. Limits of quantification lower than 20 ng.g^-1 for all analytes, high accuracy (96%-114% quantification on spiked samples nominal concentration) and interday precision (2%-12% RSD) were obtained. This method was then applied to eight sludge samples. Cefapirin and amoxicillin-diketopiperazine were detected in four samples each, at concentrations of 10.2-53.3 ng.g^-1 and 3.0-9.5 ng.g^-1 respectively. Thus, the developed method is very effective for the extraction of beta-lactams from environmental solid matrices.

Therapeutic drug monitoring of meropenem and piperacillin-tazobactam in the Singapore critically ill population - A prospective, multi-center, observational study (BLAST 1)

PURPOSE

To determine percentage of patients with sub-therapeutic beta-lactam exposure in our intensive care units (ICU) and to correlate target attainment with clinical outcomes.

MATERIALS AND METHODS

Multi-centre, prospective, observational study was conducted in ICUs from three hospitals in Singapore from July 2016 to May 2018. Adult patients (≥21 years) receiving meropenem or piperacillin-tazobactam were included. Four blood samples were obtained during a dosing interval to measure and determine attainment of therapeutic targets: unbound beta-lactam concentration above (i) minimum inhibitory concentration (MIC) at 40% (meropenem) or 50% (piperacillin) of dosing interval (40-50%fT > MIC) and (ii) 5 × MIC at 100% of dosing interval (100%fT > 5 × MIC). Correlation to clinical outcomes was evaluated using Cox regression.

RESULTS

Beta-lactam levels were highly variable among 61 patients, with trough meropenem and piperacillin levels at 21.5 ± 16.8 mg/L and 101.6 ± 81.1 mg/L respectively. Among 85 sets of blood samples, current dosing practices were able to achieve 94% success for 40-50%fT > MIC and 44% for 100%fT > 5 × MIC. Failure to achieve 40-50%fT > MIC within 48 h was significantly associated with all-cause mortality (HR: 9.0, 95% CI: 1.8-45.0), after adjustment for APACHE II score. Achievement of 100%fT > 5 × MIC within 48 h was significantly associated with shorter length of hospital stay.

CONCLUSION

Current dosing practices may be suboptimal for ICU patients. Beta-lactam TDM may be useful.

Development and validation of a liquid chromatography high-resolution mass spectrometry orbitrap method for the sensitive quantification of amoxicillin, piperacillin, tazobactam and meropenem in human faeces

Beta-lactam antibiotics are of vital importance for the treatment of infections in a broad range of patients. Although most systemically administered antibiotics will be excreted renally, a fraction will reach the gastro-intestinal tract, affecting the intestinal microbiome by eradicating a wide range of bacterial species while facilitating the growth of antimicrobial-resistant species. A better understanding of the kinetics of beta-lactam antibiotics in the gastro-intestinal tract is essential to study their role in the development of antibiotic resistance in bacteria and to help develop future therapies to prevent damage to, or restore, the intestinal microbiome. Analysis of beta-lactam antibiotics in faeces is particularly challenging due to the heterogeneous nature of the matrix, rapid degradation of some beta-lactam antibiotics in faeces and very strong ion suppression when using mass spectrometry. Sample preparation was optimized using a sequential strategy of experimental designs. It resulted in lyophilization, a MOPS buffer system and the addition of the beta-lactamase inhibitor avibactam to minimize degradation of antibiotics allowing sensitive quantification. The developed liquid chromatography method with high-resolution mass spectrometric detection was successfully validated according to bioanalytical EMA guidelines and had a linear range of 1-200 μg g^-1 lyophilized faeces for amoxicillin, piperacillin and meropenem; and 0.5-100 μg g^-1 lyophilized faeces for tazobactam. Despite the highly complex and heterogeneous composition of faeces, the accuracy (0.1-15%) and precision (1.7-12.1%) were in line with those obtained for quantification methods of beta-lactam antibiotics in plasma, the golden standard matrix for therapeutic drug monitoring. The applicability of the method was illustrated by successful quantification of piperacillin and tazobactam in faeces from an intensive care unit patient receiving piperacillin/tazobactam in a continuous intravenous infusion. Both piperacillin and tazobactam were still present six days after discontinuation of the therapy.

Penicillin Allergy Delabeling: A Multidisciplinary Opportunity

The penicillin allergy label has been consistently linked with deleterious effects that span the health care spectrum, including suboptimal clinical outcomes, the emergence of bacterial resistance, and increased health care expenditures. These risks have recently motivated professional organizations and public health institutes to advocate for the implementation of penicillin allergy delabeling initiatives; however, the burden of delabeling millions of patients is too expansive for any one discipline to bear alone. This review presents the unique perspectives and roles of various stakeholder groups involved in penicillin allergy diagnosis, assessment, and delabeling; we emphasize opportunities, barriers, and promising areas of innovation. We summarize penicillin allergy methods and tools that have proven successful in delabeling efforts. A multidisciplinary approach to delabeling patients with reported penicillin allergy, bolstered by evidence-based clinical practices, is recommended to reduce the risks that associate with the penicillin allergy label.

Piperacillin-Tazobactam Hypersensitivity: A Large, Multicenter Analysis

BACKGROUND

Piperacillin/tazobactam is a broad-spectrum penicillin. Hypersensitivity reactions are less commonly reported than with other penicillins except in patients with cystic fibrosis.

OBJECTIVE

Detailed clinical characterization of a patient cohort referred with suspected piperacillin-tazobactam hypersensitivity.

METHODS

Retrospective analysis of the demographic characteristics, clinical presentation, investigation, and management of 87 patients presenting to 5 European allergy centers. Patients underwent skin prick and intradermal testing with piperacillin/tazobactam, major (penicilloyl-polylysine) and minor (sodium penilloate) determinants, amoxicillin, benzylpenicillin, flucloxacillin, co-amoxiclav, clavulanic acid, and meropenem with immediate and, where appropriate, delayed reading of tests. Skin test-negative patients underwent drug provocation to piperacillin/tazobactam and/or other penicillins. A multistep protocol was used, depending on risk assessment.

RESULTS

Forty-eight of 87 (55%) patients were diagnosed with hypersensitivity to piperacillin/tazobactam with either positive skin or drug provocation test results, of whom 10 (21%) had a diagnosis of cystic fibrosis. Twenty-six (54%) patients presented with immediate and 22 (45%) with nonimmediate hypersensitivity. Patients with cystic fibrosis predominantly presented with nonimmediate hypersensitivity (70%). Reactions were severe in 52% of immediate reactors (Brown's anaphylaxis grade 3) and moderately severe (systemic involvement) in 75% of nonimmediate reactors. The number of patients with negative skin test results tolerating reintroduction was comparable in immediate (80%) and nonimmediate (88%) hypersensitivity. One-third of patients were cross-sensitized to other penicillins. The cross-sensitization pattern raised the possibility of tazobactam allergy in 3 patients. In 21 patients selectively sensitized to piperacillin/tazobactam (12 immediate, 9 nonimmediate), tolerance to other beta-lactams was demonstrated by drug provocation testing.

CONCLUSIONS

Piperacillin-tazobactam caused immediate and nonimmediate hypersensitivity with similar frequency. Most patients were selectively sensitized and tolerated other penicillins. Some patients may be allergic to the beta-lactamase inhibitor only.

The use of in vivo and in vitro tests in children with beta lactam allergy

BACKGROUND

Drug allergies are reactions within the context of drug hypersensitivity reactions, which are caused by immunological mechanisms due to a previously sensitising drug. Beta-lactam antibiotics (BLA) are the leading agents causing drug hypersensitivity reactions in children. The aim of this study is to evaluate the diagnostic importance of in vivo and in vitro diagnostic tests in children with suspected immediate-type BLA hypersensitivity and to investigate the frequency of their use for the final diagnosis.

METHODS

Patients admitted to the Outpatient Clinic of Division of Paediatric Allergy and Immunology with suspicion of immediate-type BLA hypersensitivity between December 2014 and December 2018 were investigated. Patients with a history of immediate reactions to BLA were examined by performing drug specific IgE, skin prick tests, intradermal tests and drug provocation tests (DPT).

RESULTS

During the study period, 148 patients were admitted to our clinic with suspected immediate-type BLA hypersensitivity. Forty-eight patients completed all assessment steps and were enrolled in the study. It has been shown that 27 patients did not have drug allergy. BLA hypersensitivity was proven in 21 patients by using in vivo test algorithm. More than half of the patients were diagnosed via skin tests with culprit drug.

CONCLUSION

Allergy work-up should be performed in patients with immediate reactions to BLA. A skin test can demonstrate BLA hypersensitivity in most patients. Thus, skin tests should be performed prior to the drug provocation test.

Failure of target attainment of beta-lactam antibiotics in critically ill patients and associated risk factors: a two-center prospective study (EXPAT)

Background

Early and appropriate antibiotic dosing is associated with improved clinical outcomes in critically ill patients, yet target attainment remains a challenge. Traditional antibiotic dosing is not suitable in critically ill patients, since these patients undergo physiological alterations that strongly affect antibiotic exposure. For beta-lactam antibiotics, the unbound plasma concentrations above at least one to four times the minimal inhibitory concentration (MIC) for 100% of the dosing interval (100%ƒT > 1–4×MIC) have been proposed as pharmacodynamic targets (PDTs) to maximize bacteriological and clinical responses. The objectives of this study are to describe the PDT attainment in critically ill patients and to identify risk factors for target non-attainment.

Methods

This prospective observational study was performed in two ICUs in the Netherlands. We enrolled adult patients treated with the following beta-lactam antibiotics: amoxicillin (with or without clavulanic acid), cefotaxime, ceftazidime, ceftriaxone, cefuroxime, and meropenem. Based on five samples within a dosing interval at day 2 of therapy, the time unbound concentrations above the epidemiological cut-off (ƒT > MIC_ECOFF and ƒT > 4×MIC_ECOFF) were determined. Secondary endpoints were estimated multivariate binomial and binary logistic regression models, for examining the association of PDT attainment with patient characteristics and clinical outcomes.

Results

A total of 147 patients were included, of whom 63.3% achieved PDT of 100%ƒT > MIC_ECOFF and 36.7% achieved 100%ƒT > 4×MIC_ECOFF. Regression analysis identified male gender, estimated glomerular filtration rate (eGFR) ≥ 90 mL/min/1.73 m², and high body mass index (BMI) as risk factors for target non-attainment. Use of continuous renal replacement therapy (CRRT) and high serum urea significantly increased the probability of target attainment. In addition, we found a significant association between the 100%ƒT > MIC_ECOFF target attainment and ICU length of stay (LOS), but no significant correlation was found for the 30-day survival.

Conclusions

Traditional beta-lactam dosing results in low target attainment in the majority of critically ill patients. Male gender, high BMI, and high eGFR were significant risk factors for target non-attainment. These predictors, together with therapeutic drug monitoring, may help ICU clinicians in optimizing beta-lactam dosing in critically ill patients.

Trial registration

Netherlands Trial Registry (EXPAT trial), NTR 5632. Registered on 7 December 2015.

Testing Strategies and Predictors for Evaluating Immediate and Delayed Reactions to Cephalosporins

BACKGROUND

Although 1% to 2% of the general population carries a cephalosporin allergy label (CAL), we lack validated testing strategies and predictors of true allergy.

OBJECTIVE

To identify cross-reactivity patterns and predictors of skin test positive (STP) in geographically disparate patients with a CAL.

METHODS

A total of 780 adult patients labeled with a CAL or penicillin allergy label (PAL) with unknown tolerance of cephalosporins identified from the Austin Hospital (Melbourne, Australia) (n = 410) and Vanderbilt University Medical Center (Nashville, TN) (n = 370) between 2014 and 2018 underwent a standardized skin testing.

RESULTS

Of 328 patients with a CAL, 29 (8.8%) tested STP to ≥1 cephalosporin(s). There were no cefazolin or ceftriaxone STP, 0 of 452 (0%), in patients with a PAL only. Of 328 patients with a CAL, 16 (4.8%) were ampicillin STP. Eleven of 16 of these patients had an initial allergy label to cephalexin. Twenty of 29 cephalosporin STP patients demonstrated tolerance to a cephalosporin with a different R1 side chain, and 8 of 14 ampicillin STP patients demonstrated tolerance to ≥1 non-amino R1 group cephalosporin. Eleven of 13 patients STP to cefazolin were skin and ingestion challenge negative to all other penicillins and cephalosporins predicted by its distinct R1/R2 groups. Seven of 15 ceftriaxone STP patients demonstrated cross-reactivity with R1-similar cephalosporins. Time since the original reaction predicted STP testing to both penicillins, adjusted odds ratio (aOR) per year 0.93 (95% confidence interval [CI]: 0.90, 0.97), and cephalosporins, aOR per year 0.71 (95% CI: 0.56, 0.90).

CONCLUSIONS

Cephalosporin cross-reactivity is based on shared R1 groupings. Increasing time since the original reaction and the presence of a PAL with unknown cephalosporin tolerance predict a lower likelihood of cephalosporin STP.

1,2,3-Triazole β-lactam conjugates as antimicrobial agents

A convenient and efficient synthesis of new triazole β-lactam conjugates using click chemistry is described. β-lactam 15 and 16 were prepared using cycloaddition strategy and propargylated at N-1 to afford compounds 17 and 18. Cu-catalyzed click reaction of these β-lactams 17 and 18 with different aryl azides provided 1,2,3-triazole conjugates 6 and 7, respectively. The products were fully characterized spectroscopically and tested against Gram-(+) and Gram-(-) bacteria. Compound 7a and 7c were found to be most active.

Influence of extracorporeal membrane oxygenation on the pharmacokinetics of ceftolozane/tazobactam: an ex vivo and in vivo study

Background

Extracorporeal membrane oxygenation (ECMO) is increasingly used in intensive care units and can modify drug pharmacokinetics and lead to under-exposure associated with treatment failure. Ceftolozane/tazobactam is an antibiotic combination used for complicated infections in critically ill patients. Launched in 2015, sparse data are available on the influence of ECMO on the pharmacokinetics of ceftolozane/tazobactam. The aim of the present study was to determine the influence of ECMO on the pharmacokinetics of ceftolozane-tazobactam.

Methods

An ex vivo model (closed-loop ECMO circuits primed with human whole blood) was used to study adsorption during 8-h inter-dose intervals over a 24-h period (for all three ceftolozane/tazobactam injections) with eight samples per inter-dose interval. Two different dosages of ceftolozane/tazobactam injection were studied and a control (whole blood spiked with ceftolozane/tazobactam in a glass tube) was performed. An in vivo porcine model was developed with a 1-h infusion of ceftolozane–tazobactam and concentration monitoring for 11 h. Pigs undergoing ECMO were compared with a control group. Pharmacokinetic analysis of in vivo data (non-compartmental analysis and non-linear mixed effects modelling) was performed to determine the influence of ECMO.

Results

With the ex vivo model, variations in concentration ranged from − 5.73 to 1.26% and from − 12.95 to − 2.89% respectively for ceftolozane (concentrations ranging from 20 to 180 mg/l) and tazobactam (concentrations ranging from 10 to 75 mg/l) after 8 h. In vivo pharmacokinetic exploration showed that ECMO induces a significant decrease of 37% for tazobactam clearance without significant modification in the pharmacokinetics of ceftolozane, probably due to a small cohort size.

Conclusions

Considering that the influence of ECMO on the pharmacokinetics of ceftolozane/tazobactam is not clinically significant, normal ceftolozane and tazobactam dosing in critically ill patients should be effective for patients undergoing ECMO.

Beta-lactam allergy in the paediatric population

Beta-lactam allergy is commonly diagnosed in paediatric patients, but over 90% of individuals reporting this allergy are able to tolerate the medications prescribed after evaluation by an allergist. Beta-lactam allergy labels are associated with negative clinical and administrative outcomes, including use of less desirable alternative antibiotics, longer hospitalizations, increasing antibiotic-resistant infections, and greater medical costs. Also, children with true IgE-mediated allergy to penicillin medications are often advised to avoid all beta-lactam antibiotics, including cephalosporins, which is likely unnecessary in greater than 97% of those reporting penicillin allergies. Most patients can be safely treated with penicillin or amoxicillin if they do not have a history compatible with IgE-mediated or systemic, delayed reactions such as Stevens-Johnson syndrome (SJS), serum sickness-like reactions, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, or acute generalized exanthematous pustulosis (AGEP). Guidance is provided on how to stratify risk of beta-lactam allergy, and on test dosing and monitoring in the outpatient setting for patients deemed low risk. Guidance for patients at higher risk of beta-lactam allergy includes criteria for appropriate referral to allergists and the use of alternative antimicrobials, such as cephalosporins, while awaiting specialist assessment.

The effect of therapeutic drug monitoring of beta-lactam and fluoroquinolones on clinical outcome in critically ill patients: the DOLPHIN trial protocol of a multi-centre randomised controlled trial

BACKGROUND

Critically ill patients undergo extensive physiological alterations that will have impact on antibiotic pharmacokinetics. Up to 60% of intensive care unit (ICU) patients meet the pharmacodynamic targets of beta-lactam antibiotics, with only 30% in fluoroquinolones. Not reaching these targets might increase the chance of therapeutic failure, resulting in increased mortality and morbidity, and antibiotic resistance. The DOLPHIN trial was designed to demonstrate the added value of therapeutic drug monitoring (TDM) of beta-lactam and fluoroquinolones in critically ill patients in the ICU.

METHODS

A multi-centre, randomised controlled trial (RCT) was designed to assess the efficacy and cost-effectiveness of model-based TDM of beta-lactam and fluoroquinolones. Four hundred fifty patients will be included within 24 months after start of inclusion. Eligible patients will be randomly allocated to either study group: the intervention group (active TDM) or the control group (non-TDM). In the intervention group dose adjustment of the study antibiotics (cefotaxime, ceftazidime, ceftriaxone, cefuroxime, amoxicillin, amoxicillin with clavulanic acid, flucloxacillin, piperacillin with tazobactam, meropenem, and ciprofloxacin) on day 1, 3, and 5 is performed based upon TDM with a Bayesian model. The primary outcome will be ICU length of stay. Other outcomes amongst all survival, disease severity, safety, quality of life after ICU discharge, and cost effectiveness will be included.

DISCUSSION

No trial has investigated the effect of early TDM of beta-lactam and fluoroquinolones on clinical outcome in critically ill patients. The findings from the DOLPHIN trial will possibly lead to new insights in clinical management of critically ill patients receiving antibiotics. In short, to TDM or not to TDM?

TRIAL REGISTRATION

EudraCT number: 2017-004677-14. Sponsor protocol name: DOLPHIN. Registered 6 March 2018 . Protocol Version 6, Protocol date: 27 November 2019.

Clinical impact of using fluoroquinolone with low antimycobacterial activity on treatment delay in tuberculosis: Hospital-based and population-based cohort study

BACKGROUND/PURPOSE

Little remains known regarding whether newer FQ with less anti-mycobacterial activity (gemifloxacin) would reduce treatment delay.

METHODS

We identified one hospital-based cohort (HBC) and one population-based cohort (PBC) including patients receiving amoxicillin/clavulanate acid (Beta-lactam), gemifloxacin (Gemi), and fluoroquinolones other than gemifloxacin (Non-Gemi FQ) prior to TB treatment.

RESULTS

A total of 201 patients in the HBC and 3544 patients in the PBC were recruited. After 1:1 propensity score matching, TB treatment delay was statistically insignificant between Beta-lactam, Gemi group, and Non-Gemi FQ group in HBC (Beta-lactam vs Gemi: 22.3 ± 21.4 d vs 28.6 ± 27.9 d, p = 0.292; Beta-lactam vs Non-Gemi FQ: 33.3 ± 26.5 d vs 50.3 ± 47.3 d, p = 0.135) and PBC (Beta-lactam vs Gemi: 26.4 ± 29.1 vs 25.0 ± 28.1, p = 0.638; Beta-lactam vs Non-Gemi FQ: 29.4 ± 36.0 d vs 32.7 ± 35.0 d, p = 0.124, Non-Gemi FQ vs Gemi: 28.4 ± 33.0 d vs 25.0 ± 28.1 d, p = 0.29).

CONCLUSION

While limited by relatively low case number, our study showed that use of gemifloxacin neither results in nor reduces delay in TB treatment. The issue of FQ use on TB treatment delay was also not observed in our study. Early survey and maintaining high clinical alertness remains the key to reducing TB treatment delay.

Cross-Reactivity to Cephalosporins and Carbapenems in Penicillin-Allergic Patients: Two Systematic Reviews and Meta-Analyses

BACKGROUND

There is no recent systematic review on the risk of cross-reactivity to cephalosporins and carbapenems in penicillin-allergic patients despite many new studies on the subject. All past reviews have several limitations such as not including any patient with a T-cell-mediated penicillin allergy.

OBJECTIVES

To determine the risk of cross-reactivity to cephalosporins and carbapenems in patients with a proven IgE- or T-cell-mediated penicillin allergy. To measure the association between R1 side chain similarity on cephalosporins and penicillins and the risk of cross-reactivity.

METHODS

MEDLINE and EMBASE were searched from January 1980 to March 2019. Studies had to include at least 10 penicillin-allergic subjects whose allergy had been confirmed by a positive skin test (ST) or drug provocation test (DPT) result. Cross-reactivity had to be assessed to at least 1 cephalosporin or carbapenem through ST or DPT. Both random-effects and fixed-effect models were used to combine data. A bioinformatic model was used to quantify the similarity between R1 side chains.

RESULTS

Twenty-one observational studies on cephalosporin cross-reactivity involving 1269 penicillin-allergic patients showed that the risk of cross-reactivity varied with the degree of similarity between R1 side chains: 16.45% (95% CI, 11.07-23.75) for aminocephalosporins, which share an identical side chain with a penicillin (similarity score = 1), 5.60% (95% CI, 3.46-8.95) for a few cephalosporins with an intermediate similarity score (range, 0.563-0.714), and 2.11% (95% CI, 0.98-4.46) for all those with low similarity scores (below 0.4), irrespective of cephalosporin generation. The higher risk associated with aminocephalosporins was observed whether penicillin allergy was IgE- or T-cell-mediated. Eleven observational studies on carbapenem cross-reactivity involving 1127 penicillin-allergic patients showed that the risk of cross-reactivity to any carbapenem was 0.87% (95% CI, 0.32-2.32).

CONCLUSIONS

Although it remains possible that these meta-analyses overestimated the risk of cross-reactivity, clinicians should consider the increased risk of cross-reactivity associated with aminocephalosporins, and to a lesser extent with intermediate-similarity-score cephalosporins, compared with the very low risk associated with low-similarity-score cephalosporins and all carbapenems when using beta-lactams in patients with a suspected or proven penicillin allergy.

Prevalence of Salmonella in broiler chickens in Kagoshima, Japan in 2009 to 2012 and the relationship between serovars changing and antimicrobial resistance

BACKGROUND

This study aimed to examine the prevalence, serovars, and antimicrobial resistance of Salmonella isolates from broiler chickens in Kagoshima, Japan. A total of 192 flocks and 3071 samples were collected from broiler chickens at local farms in Kagoshima, Japan from 2009 to 2012.

RESULT

Among the tested farms, 49.0% of flocks were positive for Salmonella, and 243 isolates were obtained from 3071 cecal samples (7.9%). All the Salmonella isolates were one of three serovars: S. Infantis (57.6%); (140/243), S. Manhattan (40.3%; 98/243 and S. Schwarzengrund (2.1%; 5/243). The proportion of S. Infantis isolates decreased from 66.0% in 2009 to 50.0% in 2011 but increased to 57.6% in 2012, while the proportion of S. Manhattan isolates significantly increased from 26.4 to 50% from 2009 to 2011, and decreased moderately to 40.9% in 2012. Most of the recovered Salmonella isolates were resistant to three antimicrobials, i.e., streptomycin (95.1%), sulfamethoxazole (91.0%) and oxytetracycline (91.4%). In contrast, all Salmonella strains were susceptible to chloramphenicol. Comparison of this study to previous studies of the antimicrobial susceptibility of Salmonella isolates showed that: the percentage of antibiotic-resistance isolates increased dramatically for two antibiotics, ampicillin (from 22.4 to 55.1%) and cefotaxime (from 9.1 to 52.7%). In contrast, the percentage of ofloxacin-resistant isolates decreased across the three survey periods, from 20.8% in 2004-2006 to 1.6% in the present study period (2009-2012). In addition, S. Infantis exhibited a variety of resistance to antimicrobials examined from sensitive to resistance to eight antimicrobials. Multidrug resistance to more than 6 six antimicrobials was detected in 113 (46.5%) of the isolates, and most of them were S. Manhattan.

CONCLUSIONS

There was a marked change in the serovars and antimicrobial resistance profiles of the Salmonella isolates in this study compared to those in previous studies. The percentage of S. Manhattan isolates increased as did the percentages of ampicillin- and cefotaxime-resistant isolates.

Analysis of synergy between beta-lactams and anti-methicillin-resistant Staphylococcus aureus agents from the standpoint of strain characteristics and binding action

In light of the increasing number of clinical cases resistant to traditional monotherapies and the lack of novel antimicrobial agents, combination therapy is an appealing solution for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we evaluated the efficacy of anti-MRSA agents, such as vancomycin (VAN), daptomycin (DAP), and linezolid (LZD), in conjunction with 13 beta-lactams and non-beta-lactams. We assessed the in vitro activities of the various combinations against 40 MRSA strains based on the maximum synergistic effect (MSE), an index calculated from the MIC change with a combination agent. Nearly all the anti-MRSA agents, which were combined with beta-lactams as well as VAN and DAP, showed a synergistic effect with arbekacin. VAN also exhibited varying degrees of synergy depending on the type of beta-lactam, whereas DAP and LZD showed similar synergy with different beta-lactams. These effects were confirmed by antibiotic kill curves, except for the apparent interaction between LZD and beta-lactams. The MSE results were analyzed according to strain characteristics including susceptibility to combination agents, staphylococcal cassette chromosome mec type, and presence of the blaZ gene; however, no obvious correlations were observed. In a fluorescence binding assay, the fluorescence intensity of boron-dipyrromethene (BODIPY)-VAN decreased, whereas that of BODIPY-DAP increased in combination with a beta-lactam agent. These findings suggest that beta-lactam combinations are promising treatment options for MRSA infections and that the type of beta-lactam combined with VAN is important for the synergistic effect.

Cephalosporin Allergy: Current Understanding and Future Challenges

Cephalosporins are commonly used antibiotics both in hospitalized patients and in outpatients. Hypersensitivity reactions to cephalosporins are becoming increasingly common with a wide range of immunopathologic mechanisms. Cephalosporins are one of the leading causes for perioperative anaphylaxis and severe cutaneous adverse reactions. Patients allergic to cephalosporins tend to tolerate cephalosporins with disparate R1 side chains but may react to other beta-lactams with common R1 side chains. Skin testing for cephalosporins has not been well validated but appears to have a good negative predictive value for cephalosporins with disparate R1 side chains. In vitro tests including basophil activation tests have lower sensitivity when compared with skin testing. Rapid drug desensitization procedures are safe and effective and have been used successfully for immediate and some nonimmediate cephalosporin reactions. Many gaps in knowledge still exist regarding cephalosporin hypersensitivity.

Important questions in drug allergy and hypersensitivity: consensus papers from the 2018 AAAAI/WAO international drug allergy symposium

This article is one of a series of international consensus documents developed from the International Drug Allergy Symposium held at the Joint Congress of the American Academy of Allergy, Asthma & Immunology/World Allergy Organization on March 1, 2018, in Orlando, Florida, USA. The symposium was sponsored by The Journal of Allergy and Clinical Immunology, The Journal of Allergy and Clinical Immunology: In Practice, and The World Allergy Organization Journal and chaired by Mariana Castells, MD, PhD, and Pascal Demoly, MD, PhD.

Controversies in Drug Allergy: Drug Allergy Pathways

Drug allergy pathways are standardized approaches for patients reporting prior drug allergies with the aim of quality improvement and promotion of antibiotic stewardship. At the International Drug Allergy Symposium during the 2018 American Academy of Allergy, Asthma, and Immunology/World Allergy Organization Joint Congress in Orlando, Florida, drug allergy pathways were discussed from international perspectives with a focus on beta-lactam allergy pathways and pragmatic approaches for acute care hospitals. In this expert consensus document, we review current pathways, and detail important considerations in devising, implementing, and evaluating beta-lactam allergy pathways for hospitalized patients. We describe the key patient and institutional factors that must be considered in risk stratification, the central feature of pathway design. We detail shared obstacles to widespread beta-lactam allergy pathway implementation and identify potential solutions to address these challenges.

Controversies in Drug Allergy: Beta-Lactam Hypersensitivity Testing

All beta-lactam use is associated with a certain rate of adverse reactions. Many of these adverse reactions result in an allergy to the beta-lactam being entered into the patient's medical record. Unfortunately, only a small minority of these recorded allergies are clinically significant immunologically mediated drug hypersensitivity. An unconfirmed allergy to beta-lactams is a significant public health risk, because patients so labeled typically do not receive narrow-spectrum penicillins and cephalosporins when clinically indicated. The alternative antibiotics they receive result in poorer clinical outcomes, increased incidence of serious antibiotic-resistant infections, prolonged hospitalizations, and greater health care utilization. There is a wide variation in beta-lactam allergy incidence and prevalence around the world, based in part on the specific beta-lactams used and overused. There is a wide variation in specific protocols used to confirm current tolerance of beta-lactams and remove these inaccurate allergy reports. Harmonizing testing protocols, when possible, may lead to more widespread use of narrow-spectrum beta-lactams, when clinically indicated, and improve patient safety worldwide. Further research is needed to better understand the regional differences in reporting beta-lactam allergy as this relates to regional differences in beta-lactam use and overuse, the frequency of clinically significant immunologically mediated beta-lactam hypersensitivity, and the optimal testing strategies to confirm current tolerance, based on presenting clinical symptoms.

Pharmacodynamic model for β-lactam regimens used in surgical prophylaxis: model-based evaluation of standard dosing regimens

Background Continual evolution of resistance among bacteria against methods of surgical prophylaxis may make currently used beta-lactam regimens inadequate. Objective To re-evaluate beta-lactam regimens in surgical prophylaxis. Setting A pharmacodynamic Monte Carlo simulation (MCS) model based on a number of patients in China. Methods Pharmacodynamic profiling using Monte Carlo simulation up to 4 hours postinfusion was conducted for standard-dose, short-term (0.5 h) and prolonged (2 to 4 h) infusions of ampicillin, cefazolin, cefotaxime, cefoxitin, cefuroxime, ertapenem, and piperacillin/tazobactam in adult patients with normal renal function. Microbiological data were incorporated. Cumulative fraction of response (CFR) was determined for each regimen against populations of S. aureus, coagulase-negative staphylococci and E. coli. The optimal CFR was defined as ≥ 90% response. Main Outcome Measure Cumulative fractions of response of pharmacodynamic target attainment. Results During the first 2 hours postinfusion, piperacillin/tazobactam 3.375 g exhibited consistently optimal cumulative fractions against S. aureus, CoNS and E. coli. Ampicillin 2 g (2 h) also displayed optimal CFRs for S. aureus and E. coli but not for coagulase-negative staphylococci. Cefoxitin 2 g didnot achieve any optimal CFRs, even via 2-h prolonged infusion (maximum 72.8% CFR for S. aureus and 64.5% CFR for E. coli). Cefazolin 2 g (4 h) and cefuroxime 1.5 g (4 h) provided desired CFRs across 4 h postinfusion for S. aureus but provided poor CFRs for coagulase-negative staphylococci and E. coli. Only ertapenem 1 g for E. coli and S. aureus and cefotaxime 1 g for E. coli consistently yielded ≥ 90% CFRs for 4 hour postinfusion. Conclusions Certain dosing regimens may warrant adjustment for improved prevention efficiency and enhanced empirical antibiotic regimens for surgical prophylaxis.

Beta-lactam carryover in arterial and central venous catheters is negligible

BACKGROUND

Therapeutic drug monitoring is used for aminoglycosides and vancomycin, and has been proposed for β-lactam antibiotics. Clinical blood samples in the ICU are often obtained via an existing vascular catheter rather than fresh needle phlebotomy. If antibiotics had previously been infused through a vascular catheter then used for blood sampling, carryover of antibiotic from the infusion to the sample might result in misleading assessments of target attainment. To address this concern we conducted a series of in vitro measurements of carryover for three commonly used antibiotics.

METHODS

We infused piperacillin-tazobactam, meropenem, and cefepime at pharmacologic concentrations through commonly used vascular catheters at our hospital and flushed the catheters. We then aspirated warmed citrated bovine blood through each catheter and measured antibiotic concentrations in each aspirate.

RESULTS

Carryover was below the limits of detection for piperacillin-tazobactam, meropenem, and vancomycin. Cefepime carryover, in contrast, was not negligible and needs to be investigated more fully.

CONCLUSION

Carryover from prior infusions does not appear to jeopardize measurements of piperacillin-tazobactam, meropenem, or vancomycin in commonly used vascular catheters at our institution. Caution in interpreting samples obtained for cefepime measurements appears advised until more data is available.

MRSA colonization status as a predictor of clinical infection: A systematic review and meta-analysis

BACKGROUND

Vancomycin is often used as empiric therapy for methicillin-resistant Staphylococcus aureus (MRSA), but can be associated with clinically important adverse events including renal failure. MRSA colonization swabs are primarily used for infection control; their use as a diagnostic test to inform the decision to add empiric vancomycin therapy has not been well elucidated.

METHODS

We performed a Medline and Embase systematic review for peer-reviewed studies reporting the diagnostic accuracy of using MRSA colonization status to predict MRSA infections. Meta-analysis was performed using Cochrane guidelines. Grey literature was excluded.

FINDINGS

29 studies were included involving 24225 patients. In cases where the pathogen is not known to be S. aureus, specificities were greater than 85% for bacteremia, lower respiratory tract infections, skin and soft tissue infections (SSTI), and all infections pooled together. Sensitivities ranged between 54.0% and 77.5%. In cases where the pathogen is known to be S. aureus, we found studies on bacteremia and SSTI and arrived at pooled estimates of sensitivities ranging between 56.6% and 56.9%, and of specificities greater than 91%. Most importantly, for most infections in settings where the prevalence of MRSA as a causative organism is below 15%, the negative predictive value of a negative MRSA colonization swab exceeds 90%.

INTERPRETATIONS

In settings of low-moderate MRSA prevalence, negative MRSA screening swabs may prevent unnecessary vancomycin use. More research is needed to assess if this strategy can mitigate the cost of screening in areas with a low MRSA colonization rate.

Daptomycin versus placebo as an adjunct to beta-lactam therapy in the treatment of Staphylococcus aureus bacteremia: study protocol for a randomized controlled trial

BACKGROUND

Staphylococcus aureus bacteremia is associated with significant morbidity and mortality. To treat this infection, the current standard of care includes intravenous anti-staphylococcal beta-lactam antibiotics and obtaining adequate source control. Combination therapy with an aminoglycoside or rifampin, despite early promise, can no longer be routinely recommended due to an absence of proven benefit and risk of harm. Daptomycin is a rapidly acting bactericidal antibiotic that is approved for the treatment of Staphylococcus aureus bacteremia as monotherapy but has not been shown to be superior to the current standard of care. As demonstrated in vitro, the addition of daptomycin to beta-lactam therapy may result in enhanced anti-staphylococcal activity. Our objective is to assess the efficacy and safety of prescribing the combination of daptomycin with cefazolin or cloxacillin for the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia in adults. We hypothesize that adjunctive therapy with daptomycin will reduce the duration of bacteremia in this population.

METHODS

The DASH-RCT trial is a randomized, double blind, placebo-controlled trial designed per the Standard Protocol Items: Recommendation for Interventional Trials (SPIRIT) and Consolidated Standards of Reporting Trials (CONSORT) guidelines. We recruit adults with confirmed MSSA bacteremia, at the McGill University Health Center. Patients are eligible if they are 18 years or older, can receive cefazolin or cloxacillin monotherapy, and are enrolled within 72 h of the first blood culture being drawn. Exclusion criteria include anaphylaxis to study drugs, having polymicrobial bacteremia, anticipated hospital admission for < 5 days, and healthcare team refusal. While receiving standard of care, study patients are randomized to a 5-day course of adjunctive daptomycin or placebo. The trial began in December 2016 and is expected to end in December 2018, after recruiting an estimated 102 patients.

DISCUSSION

The DASH-RCT will compare the use of daptomycin as an adjunct to an anti-staphylococcal beta-lactam versus placebo in the treatment of MSSA bacteremia. We believe that a short course of dual therapy will result in earlier eradication of bacteremia and that subsequent research could evaluate effects on metastatic infection, relapse, and/or mortality. Ongoing issues in the trial include a delay between presentation of infection, enrollment in the trial, and the potential for unrecognized deep foci of infection at diagnosis.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02972983 . Registered on 25 November 2016. Trial protocol: http://individual.utoronto.ca/leet/dash/dashprotocol.pdf.

Is fluoroquinolone monotherapy a useful alternative treatment for Pseudomonas aeruginosa bacteraemia?

PURPOSE

Pseudomonas aeruginosa bacteraemia is associated with high mortality, and most monotherapies are beta-lactam-based. We aimed to investigate clinical outcomes of definitive fluoroquinolone monotherapy versus beta-lactam monotherapy for P. aeruginosa bacteraemia.

METHODS

This retrospective study enrolled adult patients receiving definitive monotherapy with beta-lactam or fluoroquinolone between November 2013 and November 2014 at Taipei Veterans General Hospital. The independent risk factors for 28-day mortality were analyzed by logistic regression and propensity score-adjusted analysis.

RESULTS

Among the 105 patients enrolled, 78 patients received beta-lactams and 27 received fluoroquinolones (20 with ciprofloxacin and 7 with levofloxacin). Primary bacteraemia (39.0%) and urinary tract infections (37.1%) were the most common sources of bacteraemia. The 28-day mortality rate was 11.1% for those receiving fluoroquinolones and 32.1% for those receiving beta-lactams (P = 0.062). The 28-day mortality rate between the two groups stratified by APACHE II and Pitt bacteraemia scores showed no significant differences in each category. Propensity score-adjusted multivariate analysis revealed that definitive therapy with a fluoroquinolone was not associated with 28-day mortality (OR 0.42; 95% CI 0.08-2.23; P = 0.305).

CONCLUSIONS

Fluoroquinolone might be an alternative to beta-lactam as a definitive monotherapy for P. aeruginosa bacteraemia provided they are active in vitro. Our results could be a basis for further studies and provide a possible target for antibiotic stewardship interventions in P. aeruginosa bacteraemia.

Addressing Inpatient Beta-Lactam Allergies: A Multihospital Implementation

Addressing inaccurate penicillin allergies is encouraged as part of antibiotic stewardship in the inpatient setting. However, implementing interventions targeted at the 10% to 15% of inpatients reporting a previous penicillin allergy can pose substantial logistic challenges. We implemented a computerized guideline for patients with reported beta-lactam allergy at 5 hospitals within a single health care system in the Boston area. In this article, we describe our implementation roadmap, including both successes achieved and challenges faced. We explain key implementation steps, including assembling a team, stakeholder engagement, developing or selecting an approach, spreading the change, establishing measures, and measuring impact. The objective was to detail the lessons learned while empowering others to be part of this important, multidisciplinary work to improve the care of patients with reported beta-lactam allergies.

A UHPLC-MS/MS method for the simultaneous determination of piperacillin and tazobactam in plasma (total and unbound), urine and renal replacement therapy effluent

Piperacillin-tazobactam is a beta-lactam/beta-lactamase combination antibiotic used in patients with moderate to severe infection. Dosing of piperacillin-tazobactam requires an understanding of this patient group to maximise the effectiveness of this antibiotic and limit a further emergence of resistant pathogens. This is the first method that measures piperacillin and tazobactam simultaneously, across this range of clinically-relevant biological matrices. The calibration line was linear across the concentration range of 0.5-500μg/mL for piperacillin and 0.625-62.5μg/mL for tazobactam. All validation testing for matrix effects, precision and accuracy, specificity and stability were within 15%. A calibration equivalence study was performed to investigate the suitability of applying calibration curves prepared in an alternative matrix, with a mean bias of -10.8% identified for the application of a calibration line prepared for tazobactam in plasma only. Bias for all other calibration lines prepared in alternate matrices was within the 5% acceptance criteria. The method was successfully applied to a pharmacokinetic study of a critically ill patient receiving renal replacement therapy, with the results included.