Keeping up with the pathogens: improved antimicrobial resistance detection and prediction from Pseudomonas aeruginosa genomes.

BACKGROUND: Antimicrobial resistance (AMR) is an intensifying threat that requires urgent mitigation to avoid a post-antibiotic era. Pseudomonas aeruginosa represents one of the greatest AMR concerns due to increasing multi- and pan-drug resistance rates. Shotgun sequencing is gaining traction for in silico AMR profiling due to its unambiguity and transferability; however, accurate and comprehensive AMR prediction from P. aeruginosa genomes remains an unsolved problem. METHODS: We first curated the most comprehensive database yet of known P. aeruginosa AMR variants. Next, we performed comparative genomics and microbial genome-wide association study analysis across a Global isolate Dataset (n = 1877) with paired antimicrobial phenotype and genomic data to identify novel AMR variants. Finally, the performance of our P. aeruginosa AMR database, implemented in our AMR detection and prediction tool, ARDaP, was compared with three previously published in silico AMR gene detection or phenotype prediction tools-abritAMR, AMRFinderPlus, ResFinder-across both the Global Dataset and an analysis-naïve Validation Dataset (n = 102). RESULTS: Our AMR database comprises 3639 mobile AMR genes and 728 chromosomal variants, including 75 previously unreported chromosomal AMR variants, 10 variants associated with unusual antimicrobial susceptibility, and 281 chromosomal variants that we show are unlikely to confer AMR. Our pipeline achieved a genotype-phenotype balanced accuracy (bACC) of 85% and 81% across 10 clinically relevant antibiotics when tested against the Global and Validation Datasets, respectively, vs. just 56% and 54% with abritAMR, 58% and 54% with AMRFinderPlus, and 60% and 53% with ResFinder. ARDaP's superior performance was predominantly due to the inclusion of chromosomal AMR variants, which are generally not identified with most AMR identification tools. CONCLUSIONS: Our ARDaP software and associated AMR variant database provides an accurate tool for predicting AMR phenotypes in P. aeruginosa, far surpassing the performance of current tools. Implementation of ARDaP for routine AMR prediction from P. aeruginosa genomes and metagenomes will improve AMR identification, addressing a critical facet in combatting this treatment-refractory pathogen. However, knowledge gaps remain in our understanding of the P. aeruginosa resistome, particularly the basis of colistin AMR.

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

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

Determining Pneumocystis jirovecii Colonisation from Infection Using PCR-Based Diagnostics in HIV-Negative Individuals.

BACKGROUND: Pneumocystis jirovecii pneumonia is increasingly diagnosed with highly sensitive PCR diagnostics in immunocompromised, HIV-negative individuals. We assessed the performance of our in-house quantitative PCR with the aim to optimise interpretation. METHODS: Retrospective audit of all positive P. jirovecii qPCRs on induced sputum or BAL fluid at a single centre from 2012 to 2023. Medical and laboratory records were analysed and people with HIV were excluded. Cases were categorised as colonisation, high-probability PCP or uncertain PCP infection against a clinical gold standard incorporating clinico-radiological data. Quantitative PCR assay targeting the 5s gene was utilised throughout the time period. RESULTS: Of the 82 positive qPCRs, 28 were categorised as high-probability PCP infection, 30 as uncertain PCP and 24 as colonisation. There was a significant difference in qPCR values stratified by clinical category but not respiratory sample type. Current assay performance with a cutoff of 2.5 × 105 copies/mL had a sensitivity of 50% (95% CI, 30.65-69.35%) and specificity of 83.33% (95% CI, 62.62-95.26%). Youden Index calculated at 6.5 × 104 copies/mL had a sensitivity of 75% (56.64-87.32%, 95% CI) and specificity of 66.67% (46.71-82.03%, 95% CI). High and low cutoffs were explored. Significant variables associated with infection were age > 70 years old, the presence of fever, hypoxia or ground glass changes. CONCLUSIONS: A single qPCR cutoff cannot reliably determine P. jirovecii infection from colonisation. Low and high cutoffs are useful, however, a large "possible infection" cohort will remain where interpretation of clinic-radiological factors remains essential. Standardisation of assays with prospective validation in specific immunocompromised groups will allow greater generalisability and allow large-scale prospective assay validation to be performed.

Antibody-Mediated Serum Resistance Protects Pseudomonas aeruginosa During Bloodstream Infections.

BACKGROUND: Pseudomonas aeruginosa is a frequent pathogen isolated from bacterial bloodstream infection (BSI) and is associated with high mortality. To survive in the blood, P aeruginosa must resist the bactericidal action of complement (ie, serum killing). Antibodies usually promote serum killing through the classical complement pathway; however, "cloaking antibodies" (cAbs) have been described, which paradoxically protect bacteria from serum killing. The relevance of cAbs in P aeruginosa BSI is unknown. METHODS: Serum and P aeruginosa were collected from a cohort of 100 patients with BSI. Isolates were tested for sensitivity to healthy control serum (HCS). cAb prevalence was determined in sera. Patient sera were mixed with HCS to determine if killing of the matched isolate was inhibited. RESULTS: Overall, 36 patients had elevated titers of cAbs, and 34 isolates were sensitive to HCS killing. Fifteen patients had cAbs and HCS-sensitive isolates; of these patients, 14 had serum that protected their matched bacteria from HCS killing. Patients with cAbs were less likely to be neutropenic or have comorbidities. CONCLUSIONS: cAbs are prevalent in patients with P aeruginosa BSI and allow survival of otherwise serum-sensitive bacteria in the bloodstream. Generation of cAbs may be a risk factor for the development of BSI.

Assisted PD throughout Europe: advantages, inequities, and solution proposals.

BACKGROUND: Peritoneal dialysis provides several benefits for patients and should be offered as first line kidney replacement therapy, particularly for fragile patients. Limitation to self-care drove assisted peritoneal dialysis to evolve from family-based care to institutional programs, with specialized care givers. Some European countries have mastered this, while others are still bound by the availability of a volunteer to become responsible for treatment. METHODS: A group of leading nephrologists from 13 European countries integrated real-life application of such therapy, highlighting barriers, lessons learned and practical solutions. The objective of this work is to share and summarize several different approaches, with their intrinsic difficulties and solutions, which might helpperitoneal dialysis units to develop and offer assisted peritoneal dialysis. RESULTS: Assisted peritoneal dialysis does not mean 4 continuous ambulatory peritoneal dialysis exchanges, 7 days/week, nor does it exclude cycler. Many different prescriptions might work for our patients. Tailoring PD prescription to residual kidney function, thereby maintaining small solute clearance, reduces dialysis burden and is associated with higher technique survival. Assisted peritoneal dialysis does not mean assistance will be needed permanently, it can be a transitional stage towards individual or caregiver autonomy. Private care agencies can be used to provide assistance; other options may involve implementing PD training programs for the staff of nursing homes or convalescence units. Social partners may be interested in participating in smaller initiatives or for limited time periods. CONCLUSION: Assisted peritoneal dialysis is a valid technique, which should be expanded. In countries without structural models of assisted peritoneal dialysis, active involvement by the nephrologist is needed in order for it to become a reality.

Healthcare professional education in shared decision making in the context of chronic kidney disease: a scoping review.

RATIONALE & OBJECTIVE: Shared decision making (SDM) is a collaborative effort between healthcare professionals, individuals with CKD whereby clinical evidence, expected outcomes and potential side-effects are balanced with individual values and beliefs to provide the best mutually decided treatment option. Meaningful SDM is supported by effective training and education. We aimed to identify the available evidence on SDM training and education of healthcare professionals caring for people with chronic kidney disease. We aimed to identify existing training programs and to explore what means are used to evaluate the quality and effectiveness of these educational efforts. METHODOLOGY: We performed a scoping review to study the effectiveness of training or education about shared decision making of healthcare professionals treating patients with kidney disease. EMBASE, MEDLINE, CINAHL and APA PsycInfo were searched. RESULTS: After screening of 1190 articles, 24 articles were included for analysis, of which 20 were suitable for quality appraisal. These included 2 systematic reviews, 1 cohort study, 7 qualitative studies, and 10 studies using mixed methods. Study quality was varied with high quality (n = 5), medium quality (n = 12), and low quality (n = 3) studies. The majority of studies (n = 11) explored SDM education for nurses, and physicians (n = 11). Other HCP profiles included social workers (n = 6), dieticians (n = 4), and technicians (n = 2). Topics included education on SDM in withholding of dialysis, modality choice, patient engagement, and end-of-life decisions. LIMITATIONS: We observed significant heterogeneity in study design and varied quality of the data. As the literature search is restricted to evidence published between January 2000 and March 2021, relevant literature outside of this time window has not been taken into account. CONCLUSIONS: Evidence on training and education of SDM for healthcare professionals taking care of patients with CKD is limited. Curricula are not standardized, and educational and training materials do not belong to the public domain. The extent to which interventions have improved the process of shared-decision making is tested mostly by pre-post testing of healthcare professionals, whereas the impact from the patient perspective for the most part remains untested.

Comparing the use of midline catheters versus peripherally inserted central catheters for patients requiring peripherally compatible therapies: A pilot randomised controlled trial (the compact trial).

BACKGROUND: Midline catheter (MC) use has increased in acute-care settings, particularly for patients with difficult venous access or requiring peripherally compatible intravenous therapy for up-to 14 days. Our aim was to assess feasibility and generate clinical data comparing MCs with Peripherally Inserted Central Catheters (PICCs). METHODS: A two-arm parallel group pilot randomised controlled trial (RCT), comparing MCs with PICCs, was conducted in a large tertiary hospital in Queensland between September 2020 and January 2021. The primary outcome was study feasibility, measured against rates of eligibility (>75%), consent (>90%), attrition (<5%); protocol adherence (>90%) and missing data (<5%). The primary clinical outcome was all-cause device failure. RESULTS: In total, 25 patients were recruited. The median patient age was 59-62 years; most patients were overweight/obese, with ≥2 co-morbidities. PRIMARY OUTCOMES: The eligibility and protocol adherence criteria were not met; of 159 screened patients, only 25 (16%) were eligible, and three patients did not receive their allocated intervention post-randomisation (88% adherence). All-cause failure occurred in two patients allocated to MC (20%) and one PICC (8.3%). CONCLUSIONS: Our study found that a fully powered RCT testing MCs compared with PICCs is not currently feasible in our setting. We recommend a robust process evaluation before the introduction of MCs into clinical practice.

State of the art: Intrapartum antibiotics in cesarean section, the infant microbiota and allergic diseases.

With increasing rates of cesarean section worldwide and international guidelines advising pre-incision antibiotics, neonatal exposure to pre-birth antibiotics is higher than ever before. Emerging evidence has raised concern regarding the impact of such antibiotics on the neonatal intestinal microbiota, immune system development and health conditions later in life. This narrative review investigates current protocols for intrapartum prophylactic antibiotics in cesarean section, how this and other factors may affect the neonatal intestinal microbiota and whether intrapartum antibiotics used for cesarean section are linked to the development of allergic disease.

A contemporary case series of Pseudomonas aeruginosa infective endocarditis.

Pseudomonas aeruginosa infective endocarditis (IE) is a rare disease associated with high mortality and complications. Here, we describe a contemporary set of patients aiming to improve the understanding of risk factors, clinical features, treatments, and outcomes. This retrospective case series reviewed cases from 3 tertiary metropolitan hospitals between January 1999 and January 2019. prespecified data were collected for each case, with a review of risk factors, valve involvement, acquisition, treatment, and complications. Fifteen patients were identified over a 20 years period. All patients presented with fever, 5/15 had preexisting prosthetic valve with valvular heart disease in 7/15 patients making it the most common risk factor. Intravenous drug use (IVDU) was the source in only 6/15 cases with healthcare associated infection and left-sided valvular involvement being more common than previous reports both occurring in 9/15 cases. Complications occurred in 11/15 patients with a 30 days mortality of 13%. Surgery was performed in 7/15 patients and 9/15 patients received antibiotic combination therapy. One year mortality was higher in those with increasing age, comorbidities, left-sided valve involvement, presence of predefined complications, and antibiotic monotherapy. Development of resistance occurred in 2 cases that received monotherapy. P aeruginosa IE remains a rare disease with high mortality and secondary complications.

COVID-19 (Omicron strain) hospital admissions from a virtual ward - who required further care?

BACKGROUND: The COVID-19 virtual ward was created to provide care for people at home with COVID-19. Given this was a new model of care, little was known about the clinical characteristics and outcomes of patients requiring admission to hospital from the virtual ward platform. The aims were to characterise hospital admission volume, patient epidemiology, clinical characteristics, and outcome from a virtual ward in the setting of an Omicron (BA.1, BA.2) outbreak. METHODS: A retrospective observational study was performed for all virtual ward patients admitted from 1st January 2022 to 25th March 2022 (over 16 years old). Epidemiological, clinical and laboratory data was reviewed on all patients who required hospital admission. RESULTS: A total of 7021 patients were cared for on the virtual ward over the study period with 473 referred to hospital for assessment. Twenty-six (0.4%) patients were admitted to hospital during their care on the ward. Twenty-two (84.6%) admissions were COVID-19 related. Fifty three percent of the hospitalised patients were fully vaccinated and 11 had received prior therapeutics for COVID-19. Shortness of breath was the most common reason for escalation to hospital. Chest pain was the second most common reason and the most common diagnosis after investigation was non-cardiac chest pain. CONCLUSIONS: Few patients required admission from the virtual ward in the setting of the Omicron variant (BA.1, BA.2) as a direct result of COVID-19 disease and virtual ward care. Shortness of breath and chest pain were the most common symptoms driving further clinical care.

Outcomes of octogenarians and nonagenarians with Pseudomonas aeruginosa bacteremia: a multicenter retrospective study.

BACKGROUND: P. aeruginosa bacteremia is a common and severe infection carrying high mortality in older adults. We aimed to evaluate outcomes of P. aeruginosa bacteremia among old adults (≥ 80 years). METHODS: We included the 464/2394 (19%) older adults from a retrospective multinational (9 countries, 25 centers) cohort study of individuals hospitalized with P. aeruginosa bacteremia. Bivariate and multivariable logistic regression models were used to evaluate risk factors for 30-day mortality among older adults. RESULTS: Among 464 adults aged ≥ 80 years, the mean age was 84.61 (SD 3.98) years, and 274 (59%) were men. Compared to younger patients, ≥ 80 years adults had lower Charlson score; were less likely to have nosocomial acquisition; and more likely to have urinary source. Thirty-day mortality was 30%, versus 27% among patients 65-79 years (n = 894) and 25% among patients < 65 years (n = 1036). Multivariate analysis for predictors of mortality among patients ≥ 80 years, demonstrated higher SOFA score (odds ratio [OR] 1.36, 95% confidence interval [CI] 1.23-1.51, p < 0.001), corticosteroid therapy (OR 3.15, 95% CI: 1.24-8.01, p = 0.016) and hospital acquired P. aeruginosa bacteremia (OR 2.30, 95% CI: 1.33-3.98, p = 0.003) as predictors. Appropriate empirical therapy within 24 h, type of definitive anti-pseudomonal drug, and type of regimen (monotherapy or combination) were not associated with 30-day mortality. CONCLUSIONS: In older adults with P. aeruginosa bacteremia, background conditions, place of acquisition, and disease severity are associated with mortality, rather than the antimicrobial regimen. In this regard, preventive efforts and early diagnosis before organ failure develops might be beneficial for improving outcomes.

Rapid fluoroquinolone resistance detection in Pseudomonas aeruginosa using mismatch amplification mutation assay-based real-time PCR.

Background. Antimicrobial resistance (AMR) is an ever-increasing global health concern. One crucial facet in tackling the AMR epidemic is earlier and more accurate AMR diagnosis, particularly in the dangerous and highly multi-drug-resistant ESKAPE pathogen, Pseudomonas aeruginosa.Objectives. We aimed to develop two SYBR Green-based mismatch amplification mutation assays (SYBR-MAMAs) targeting GyrA T83I (gyrA248) and GyrA D87N, D87Y and D87H (gyrA259). Together, these variants cause the majority of fluoroquinolone (FQ) AMR in P. aeruginosa.Methods. Following assay validation, the gyrA248 and gyrA259 SYBR-MAMAs were tested on 84 Australian clinical P. aeruginosa isolates, 46 of which demonstrated intermediate/full ciprofloxacin resistance according to antimicrobial susceptibility testing.Results. Our two SYBR-MAMAs correctly predicted an AMR phenotype in the majority (83%) of isolates with intermediate/full FQ resistance. All FQ-sensitive strains were predicted to have a sensitive phenotype. Whole-genome sequencing confirmed 100 % concordance with SYBR-MAMA genotypes.Conclusions. Our GyrA SYBR-MAMAs provide a rapid and cost-effective method for same-day identification of FQ AMR in P. aeruginosa. An additional SYBR-MAMA targeting the GyrB S466Y/S466F variants would increase FQ AMR prediction to 91 %. Clinical implementation of our assays will permit more timely treatment alterations in cases where decreased FQ susceptibility is identified, leading to improved patient outcomes and antimicrobial stewardship.

Infection control behaviours, intra-household transmission and quarantine duration: a retrospective cohort analysis of COVID-19 cases.

OBJECTIVES: To study COVID-19 (Delta Variant) cases and close contacts co-located within households. Focusing on epidemiology of transmission of COVID-19, quarantine duration and utilisation of infection control behaviours under a telehealth model of care in an elimination setting. METHODS: A retrospective cohort analysis examined household spread of infection, duration of quarantine and change in PCR CT value during illness. A survey explored infection control behaviours used by household members during isolation and quarantine. RESULTS: The cohort was 141 individuals in 35 households. Thirty-seven were index cases, and 48 became positive during quarantine, most within 10 days. Whole-household infection occurred in 12 households with multiple members. Behaviours focused on fomite transmission reduction rather than preventing aerosol transmission. The median duration of close contact household quarantine was 25 days. The majority of COVID-19 cases were de-isolated after 14 days with no evidence of further community transmission. CONCLUSION: Intrahousehold transmission was not universal and, if it occurred, usually occurred quickly. Behaviours utilised focused on fomites, suggesting a need for improved education regarding the potential utilisation of strategies to prevention the transmission of aerosols. Households experienced long durations of home-based quarantine. IMPLICATIONS FOR PUBLIC HEALTH: The impact of long quarantine durations must be considered, particularly where most community benefit from quarantine is achieved within 10 days from exposure in the setting of the Delta Variant. Education of households regarding aerosol risk reduction is a potential strategy in the household setting of individuals at risk of disease progression.

Availability of assisted peritoneal dialysis in Europe: call for increased and equal access.

BACKGROUND: Availability of assisted PD (asPD) increases access to dialysis at home, particularly for the increasing numbers of older and frail people with advanced kidney disease. Although asPD has been widely used in some European countries for many years, it remains unavailable or poorly utilized in others. A group of leading European nephrologists have therefore formed a group to drive increased availability of asPD in Europe and in their own countries. METHODS: Members of the group filled in a proforma with the following headings: personal experience, country experience, who are the assistants, funding of asPD, barriers to growth, what is needed to grow and their top three priorities. RESULTS: Only 5 of the 13 countries surveyed provided publicly funded reimbursement for asPD. The use of asPD depends on overall attitudes to PD, with all respondents mentioning the need for nephrology team education and/or patient education and involvement in dialysis modality decision making. CONCLUSIONS AND CALL TO ACTION: Many people with advanced kidney disease would prefer to have their dialysis at home, yet if the frail patient chooses PD most healthcare systems cannot provide their choice. AsPD should be available in all countries in Europe and in all renal centres. The top priorities to make this happen are education of renal healthcare teams about the advantages of PD, education of and discussion with patients and their families as they approach the need for dialysis, and engagement with policymakers and healthcare providers to develop and support assistance for PD.

Duration of Treatment for Pseudomonas aeruginosa Bacteremia: a Retrospective Study.

INTRODUCTION: There is no consensus regarding optimal duration of antibiotic therapy for Pseudomonas aeruginosa bacteremia. We aimed to evaluate the impact of short antibiotic course. METHODS: We present a retrospective multicenter study including patients with P. aeruginosa bacteremia during 2009-2015. We evaluated outcomes of patients treated with short (6-10 days) versus long (11-15 days) antibiotic courses. The primary outcome was a composite of 30-day mortality or bacteremia recurrence and/or persistence. Univariate and inverse probability treatment-weighted (IPTW) adjusted multivariate analysis for the primary outcome was performed. To avoid immortal time bias, the landmark method was used. RESULTS: We included 657 patients; 273 received a short antibiotic course and 384 a long course. There was no significant difference in baseline characteristics of patients. The composite primary outcome occurred in 61/384 patients in the long-treatment group (16%) versus 32/273 in the short-treatment group (12%) (p = 0.131). Mortality accounted for 41/384 (11%) versus 25/273 (9%) of cases, respectively. Length of hospital stay was significantly shorter in the short group [median 13 days, interquartile range (IQR) 9-21 days, versus median 15 days, IQR 11-26 days, p = 0.002]. Ten patients in the long group discontinued antibiotic therapy owing to adverse events, compared with none in the short group. On univariate and multivariate analyses, duration of therapy was not associated with the primary outcome. CONCLUSIONS: In this retrospective study, 6-10 days of antibiotic course for P. aeruginosa bacteremia were as effective as longer courses in terms of survival and recurrence. Shorter therapy was associated with reduced length of stay and less drug discontinuation.

A Quality Improvement Process to Increase and Sustain a Peritoneal Dialysis Programme in the United Kingdom.

INTRODUCTION: Peritoneal dialysis (PD) remains underutilised in the West. The proportion of patients in the UK starting renal replacement therapy (RRT) with PD fell from 7.2% in 2011 to 6.0% in 2016. At our centre, 8.4% of dialysis patients received PD in April 2014. Evidence suggests that home dialysis improves patient clinical outcomes; therefore, a target was agreed to achieve 25% of dialysis patients receiving PD by 2018. METHODS: A rapid improvement process was introduced, as a quality improvement tool, to increase and sustain the PD programme. With multidisciplinary team support for PD growth, a nephrologist was trained to insert PD catheters. Nurses were trained to provide patients with balanced pre-dialysis information and discuss alternative dialysis modalities with haemodialysis (HD) patients. The "Acceptance, Choice and Empowerment" project raised awareness of home therapy choices, using a peer educator model specifically for ethnic minority patients. Lean methodologies were used to ensure continuous quality improvement. RESULTS: PD uptake increased from 37 to 84 patients, giving a PD penetration increase from 8.4% to 19.1% between April 2014 and March 2018. Catheter insertions increased from 94 at the end of QI Period 1 to 185 at the end of QI Period 2, representing a 97% increase, with the medical/surgical split remaining stable. Peritonitis rates remained stable, and PD drop off to HD reduced from 52% to 41% during the same period. CONCLUSIONS: By implementing a rapid improvement process and embedding a quality improvement programme, the number of incidents and prevalent PD patients increased and was sustained.

Evaluating Mono- and Combination Therapy of Meropenem and Amikacin against Pseudomonas aeruginosa Bacteremia in the Hollow-Fiber Infection Model.

Debate continues as to the role of combination antibiotic therapy for the management of Pseudomonas aeruginosa infections. We studied the extent of bacterial killing by and the emergence of resistance to meropenem and amikacin as monotherapies and as a combination therapy against susceptible and resistant P. aeruginosa isolates from bacteremic patients using the dynamic in vitro hollow-fiber infection model. Three P. aeruginosa isolates (meropenem MICs of 0.125, 0.25, and 64 mg/L) were used, simulating bacteremia with an initial inoculum of ~1 × 105 CFU/mL and the expected pharmacokinetics of meropenem and amikacin in critically ill patients. For isolates susceptible to amikacin and meropenem (isolates 1 and 2), the extent of bacterial killing was increased with the combination regimen compared with the killing by monotherapy of either antibiotic. Both the combination and meropenem monotherapy were able to sustain bacterial killing throughout the 7-day treatment course, whereas regrowth of bacteria occurred with amikacin monotherapy after 12 h. For the meropenem-resistant P. aeruginosa isolate (isolate 3), only the combination regimen demonstrated bacterial killing. Given that tailored antibiotic regimens can maximize potential synergy against some isolates, future studies should explore the benefit of combination therapy against resistant P. aeruginosa. IMPORTANCE Current guidelines recommend that aminoglycosides should be used in combination with ß-lactam antibiotics as initial empirical therapy for serious infections, and otherwise, patients should receive ß-lactam antibiotic monotherapy. Given the challenges associated with studying the clinical effect of different antibiotic strategies on patient outcomes, useful data for subsequent informed clinical testing can be obtained from in vitro models like the hollow-fiber infection model (HFIM). Based on the findings of our HFIM, we propose that the initial use of combination therapy with meropenem and amikacin provides some bacterial killing against carbapenem-resistant P. aeruginosa isolates. For susceptible isolates, combination therapy may only be of benefit in specific patient populations, such as critically ill or immunocompromised patients. Therefore, clinicians may want to consider using the combination therapy for the initial management and ceasing the aminoglycosides once antibiotic susceptibility results have been obtained.

Adherence to self-administered biologic disease-modifying antirheumatic drugs across health-system specialty pharmacies.

PURPOSE: Adherence to self-administered biologic disease-modifying antirheumatic drugs (bDMARDs) is necessary for therapeutic benefit. Health-system specialty pharmacies (HSSPs) have reported high adherence rates across several disease states; however, adherence outcomes in rheumatoid arthritis (RA) populations have not yet been established. METHODS: We performed a multisite retrospective cohort study including patients with RA and 3 or more documented dispenses of bDMARDs from January through December 2018. Pharmacy claims were used to calculate proportion of days covered (PDC). Electronic health records of patients with a PDC of <0.8 were reviewed to identify reasons for gaps in pharmacy claims (true nonadherence or appropriate treatment holds). Outcomes included median PDC across sites, reasons for treatment gaps in patients with a PDC of <0.8, and the impact of adjusting PDC when accounting for appropriate therapy gaps. RESULTS: There were 29,994 prescriptions for 3,530 patients across 20 sites. The patient cohort was mostly female (75%), with a median age of 55 years (interquartile range [IQR], 42-63 years). The median PDC prior to chart review was 0.94 (IQR, 0.83-0.99). Upon review, 327 patients had no appropriate treatment gaps identified, 6 patients were excluded due to multiple unquantifiable appropriate gaps, and 420 patients had an adjustment in the PDC denominator due to appropriate treatment gaps (43 instances of days' supply adjusted based on discordant days' supply information between prescriptions and physician administration instructions, 11 instances of missing fills added, and 421 instances of clinically appropriate treatment gaps). The final median PDC after accounting for appropriate gaps in therapy was 0.95 (IQR, 0.87-0.99). CONCLUSION: This large, multisite retrospective cohort study was the first to demonstrate adherence rates across several HSSPs and provided novel insights into rates and reasons for appropriate gaps in therapy.