Efficacy and safety of aminoglycoside monotherapy: systematic review and meta-analysis of randomized controlled trials

Clinical pharmacokinetics of antimicrobials in critical care: a narrative review

INTRODUCTION

The management of critically ill septic patients presents considerable challenges due to multifaceted physiological alterations. Rapid changes such as fluid shifts, hyperdynamic states, and altered renal clearance often require special attention for better clinical outcomes. Vital organ dysfunction, with or without MODS, often necessitates supportive management like RRT, ventilatory support, and ECMO. These interventions can significantly affect the PK/PD of administered antimicrobials, complicating effective treatment.

AREA COVERED

Patient-specific parameters such as age, weight, and comorbid illnesses (e.g. cystic fibrosis, burns, and immunocompromised states) are critical determinants of antimicrobial pharmacokinetics. Understanding PK/PD determinants is crucial for developing optimized dosing regimens that enhance therapeutic efficacy and minimize toxicity in critically ill patients.

EXPERT OPINION

Incorporating pharmacometrics approaches in dose optimization can significantly improve patient outcomes. This review focuses on the nuances of PK/PD for optimized antimicrobial dosing in critically ill septic patients, emphasizing the importance of individualized treatment plans to address the complex and dynamic needs of this patient population. The adoption of these advanced pharmacokinetic and pharmacodynamic principles into clinical practice is essential for advancing patient care and optimizing therapeutic outcomes in critically ill patients.

Amikacin treatment in urinary tract infection patients: evaluating the risk of acute kidney injury - a retrospective cohort study

The rise in ESBL-producing and carbapenem-resistant Gram-negative bacterial infections is alarming. Aminoglycosides remain attractive for treating urinary tract infections (UTIs). However, aminoglycosides-associated acute kidney injury (AKI) raises concerns, especially in patients with underlying renal impairment. We conducted a retrospective cohort study to evaluate the risk of AKI in patients with UTI empirically treated with amikacin. Among 395 patients (median age 41.9 years [IQR 28.3-67.1], 342 [86.6%] female), 162 (41.0%) received amikacin and 233 (59.0%) were empirically treated with other antibiotics. AKI incidence was low (5.6%) and not associated with amikacin exposure (OR 0.56, 95% CI 0.22-1.43, p = 0.23), even in those with pre-existing renal impairment or AKI on admission. The clinical outcomes (including cure by the third day, AKI, maximal creatinine, length of stay, mortality, and readmission) did not differ between the groups. Once-daily amikacin may offer a safe UTI treatment option amid increasing multi-drug resistance.

Prevalence of Brucella melitensis and Brucella abortus aminoglycoside-resistant isolates: a systematic review and meta-analysis

INTRODUCTION

Aminoglycosides are vital antibiotics for treating Brucella infections, because they interfere with bacterial protein production and are often combined with other antibiotics. They are cost-effective, have fewer side effects, and can penetrate biofilms. The prevalence of brucellosis has increased in recent years, increasing the need for effective treatments. In addition, the emergence of multidrug-resistant Brucella strains has highlighted the need for an updated and comprehensive understanding of aminoglycoside resistance. This systematic review aimed to provide a comprehensive overview of the global prevalence of aminoglycoside resistance in B. melitensis and B. abortus.

METHODS

A systematic search of online databases was conducted and eligible studies met certain criteria and were published in English. Quality assessment was performed using the JBI Checklist. A random-effects model was fitted to the data, and meta-regression, subgroup, and outlier/influential analyses were performed. The analysis was performed using R and the metafor package.

RESULTS

The results of this systematic review and meta-analysis suggested that the average prevalence rates of streptomycin, gentamicin, and amikacin resistance were 0.027 (95% confidence interval [CI], 0.015-0.049), 0.023 (95% CI, 0.017-0.032), and 0.008 (95% CI, 0.002-0.039), respectively. The prevalence of streptomycin resistance was higher in the unidentified Brucella group than in the B. abortus and B. melitensis groups (0.234, 0.046, and 0.017, respectively; p < 0.02). The prevalence of gentamicin resistance increased over time (r = 0.064; 95% CI, 0.018 to 0.111; p = 0.007). The prevalence of resistance did not correlate with the quality score for any antibiotic. Funnel plots showed a potential asymmetry for streptomycin and gentamicin. These results suggest a low prevalence of antibiotic resistance in the studied populations.

CONCLUSION

The prevalence of aminoglycoside resistance in B. melitensis and B. abortus was low. However, gentamicin resistance has increased in recent years. This review provides a comprehensive and updated understanding of aminoglycoside resistance in B. melitensis and B. abortus.

Global impact of antibacterial resistance in patients with hematologic malignancies and hematopoietic cell transplant recipients

Patients with hematologic malignancies and hematopoietic cell transplant (HCT) recipients are at high risk of developing bacterial infections. These patients may suffer severe consequences from these infections if they do not receive immediate effective therapies, and thus are uniquely threatened by antimicrobial-resistant bacteria. Here, we outline how the emergence of specific resistant bacteria threatens the effectiveness of established approaches to prevent and treat infections in this population. The emergence of fluoroquinolone resistance among Enterobacterales and viridans group streptococci may decrease the effectiveness of fluoroquinolone prophylaxis during neutropenia. The emergence of Enterobacterales that produce extended-spectrum β-lactamases or carbapenemases and of increasingly resistant Pseudomonas aeruginosa may result in neutropenic patients experiencing delayed time to active antibacterial therapy, and consequently worse clinical outcomes. The ability to select targeted antibacterial therapies after the availability of susceptibility data may be limited in patients infected with metallo-β-lactamase-producing Enterobacterales and difficult-to-treat P. aeruginosa. Vancomycin-resistant enterococci and Stenotrophomonas maltophilia can cause breakthrough infections in patients already being treated with broad-spectrum β-lactam antibiotics. Resistance can also limit the ability to provide oral stepdown antibacterial therapy for patients who could otherwise be discharged from hospitalization. We also outline strategies that have the potential to mitigate the negative impact of antimicrobial resistance, including interventions based on active screening for colonization with resistant bacteria and the use of novel rapid diagnostic assays. Additional research is needed to better understand how these strategies can be leveraged to combat the emerging crisis of antimicrobial resistance in patients with hematologic malignancies and HCT recipients.

Consensus for the treatment of upper urinary tract infections during pregnancy

Objectives

To generate evidence-based recommendations through formal consensus regarding the treatment of upper urinary tract infections during gestation.

Materials and methods

Experts in microbiology, public health, internal medicine, infectious diseases, obstetrics, maternal fetal medicine and obstetric and gynecological infections participated in the consensus development group. The group also included professionals with training in clinical epidemiology, systematic data search, and representatives from the Health Secretariat and the Bogota Obstetrics and Gynecology Association. The participants disclosed their conflicts of interest. Starting with a clinical question, outcomes were graded and a systematic search was conducted in the Medline via PubMed, Embase, Lilacs, and Bireme databases. The search was expanded to include institutional repositories and antimicrobial resistance surveillance systems, with no language or date restrictions. The search was updated on October 1, 2022. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology was used to assess the quality of the evidence and determine the strength of the recommendations. Finally, the RAND/UCLA (Research and Development/University of California Los Angeles) methodology was applied for the formal consensus. This document was reviewed by academic peers before publication.

Results

The following are the consensus recommendations. Recommendation 1. The initial management of pregnant women with upper urinary tract infections (UTIs) should be approached in a hospital setting. Recommendation 2. The use of second generation cephalosporins is the suggested first option for empirical antimicrobial management in pregnant women with upper UTI in order to improve the rates of clinical and microbiological cure. Recommendation 3. Because of the risk-benefit balance, the use of aminoglycosides is suggested as a second option for empirical antimicrobial treatment in pregnant women presenting with upper UTIs in the second and third trimester. Recommendation 4. The use of third-generation cephalosporins is suggested as the third option for empirical antimicrobial treatment in pregnant women with upper UTIs given that the risk of inducing microbial resistance is high with this group of antibiotics. Recommendation 5. The use of carbapenems is suggested as a first option in pregnant women with upper UTIs and a history of infections caused by microorganisms with resistance to third or fourth-generation cephalosporins. Recommendation 6. The use of aminoglycosides or fourth-generation cephalosporins is suggested as a second option in pregnant women with upper UTIs and a history of infection caused by microorganisms with resistance to third-generation cephalosporins, taking risk-benefit into account. Recommendation 7. The use of piperacillin/tazobactam is suggested as a third option in pregnant women with upper UTIs and a history of infection caused by microorganisms with resistance to third or fourthgeneration cephalosporins. Recommendation 8. Getting a urine culture is recommended in pregnant women with upper UTIs before initiating empirical antimicrobial treatment. Recommendation 9. In pregnant women with upper UTIs, it is suggested to modify therapy in accordance with the results of the sensitivity test when the culture report shows resistance to the antimicrobial agent initiated empirically. Recommendation 10. In pregnant women hospitalized due to upper UTIs, it is suggested to switch to oral antimicrobial therapy after at least 48 hours of modulation of the systemic inflammatory response and the clinical signs of infection, and when tolerance to oral intake is adequate. Recommendation 11. In pregnant women with upper UTIs with no complications secondary to the primary infection, it is recommended to administer antibiotic therapy for a period of 7 to 10 days.

Conclusions

It is expected that with this Colombian upper UTI consensus variability in clinical practice will be reduced. It is recommended that groups doing research in maternal fetal medicine assess the implementation and effectiveness of these recommendations.

Assessing Rates of Co-Resistance and Patient Outcomes in Multidrug-Resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) Pseudomonas aeruginosa infections are associated with poor patient outcomes due to complex co-resistance patterns. We described common co-resistance patterns, clinical characteristics, and associated outcomes in patients admitted with an MDR P. aeruginosa. This national, multicenter, retrospective cohort study within the Veterans Affairs included adults hospitalized with a MDR P. aeruginosa infection (January 2015-December 2020) per Centers for Disease Control definition. Clinical outcomes were compared among those with differing MDR P. aeruginosa co-resistance: resistant to carbapenems and extended-spectrum cephalosporins and piperacillin-tazobactam (CARB/ESC/PT) versus without CARB/ESC/PT resistance; resistant to carbapenems and extended-spectrum cephalosporins and fluoroquinolone (CARB/ESC/FQ) versus without CARB/ESC/FQ resistance. We included 3,763 hospitalized patients. Co-resistance to CARB/ESC/PT was observed in 42.7%, and to CARB/ESC/FQ in 40.7%. The lowest co-resistance rates were observed with ceftolozane-tazobactam (6.2%, n = 6/97; 12.5%, n = 10/80, respectively) and ceftazidime-avibactam (5.2%, n = 5/97; 12.5%, n = 10/80, respectively). Overall, 14.2% of patients died during hospitalization, 59.7% had an extended length of stay, and 14.9% had reinfection with hospitalization. Outcomes were similar between patients with MDR P. aeruginosa strains with and without co-resistance to CARB/ESC/PT and CARB/ESC/FQ. Among a national cohort of patients hospitalized with MDR P. aeruginosa infections, co-resistance to three classes of standard of care antibiotics, such as carbapenem, extended-spectrum cephalosporins, and piperacillin-tazobactam or fluoroquinolones, exceeded 40% in our study population, posing great concerns for selecting appropriate empirical therapy. Clinical outcomes were poor for all patients, regardless of different co-resistance patterns. New treatment options are needed for hospitalized patients with suspected or confirmed MDR P. aeruginosa infections. IMPORTANCE We studied antibiotic co-resistance patterns in a national group of hospitalized patients with infections due to multidrug-resistant (MDR) Pseudomonas aeruginosa, a type of bacteria that resists treatment to at least three classes of antibiotics. Co-resistance to antibiotic classes most typically used for treatment was common, which makes selecting appropriate antibiotics to successfully treat the infections difficult. Outcomes, including death, were poor for all patients in our study, regardless of the different patterns of co-resistance to common antibiotic classes. New antibiotics are needed to help treat hospitalized patients with MDR P. aeruginosa infections.

Antimicrobial Challenge in Acute Care Surgery

The burden of infections in acute care surgery (ACS) is huge. Surgical emergencies alone account for three million admissions per year in the United States (US) with estimated financial costs of USD 28 billion per year. Acute care facilities and ACS patients represent boost sanctuaries for the emergence, development and transmission of infections and multi-resistant organisms. According to the World Health Organization, healthcare-associated infections affected around 4 million cases in Europe and 1.7 million in the US alone in 2011 with 39,000 and 99,000 directly attributable deaths, respectively. In this scenario, antimicrobial resistance arose as a public-health emergency that worsens patients' morbidity and mortality and increases healthcare costs. The optimal patient care requires the application of comprehensive evidence-based policies and strategies aiming at minimizing the impact of healthcare associated infections and antimicrobial resistance, while optimizing the treatment of intra-abdominal infections. The present review provides a snapshot of two hot topics, such as antimicrobial resistance and systemic inflammatory response, and three milestones of infection management, such as source control, infection prevention, and control and antimicrobial stewardship.

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 β-lactam antibiotics as initial empirical therapy for serious infections, and otherwise, patients should receive β-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.

Bacterial genotypic and patient risk factors for adverse outcomes in Escherichia coli bloodstream infections: a prospective molecular epidemiological study

OBJECTIVES

Escherichia coli bloodstream infections have shown a sustained increase in England, for reasons that are unknown. Furthermore, the contribution of MDR lineages such as ST131 to overall E. coli disease burden and outcome is undetermined.

METHODS

We genome-sequenced E. coli blood isolates from all patients with E. coli bacteraemia in north-west London from July 2015 to August 2016 and assigned MLST genotypes, virulence factors and AMR genes to all isolates. Isolate STs were then linked to phenotypic antimicrobial susceptibility, patient demographics and clinical outcome data to explore relationships between the E. coli STs, patient factors and outcomes.

RESULTS

A total of 551 E. coli genomes were analysed. Four STs (ST131, 21.2%; ST73, 14.5%; ST69, 9.3%; and ST95, 8.2%) accounted for over half of cases. E. coli genotype ST131-C2 was associated with phenotypic non-susceptibility to quinolones, third-generation cephalosporins, amoxicillin, amoxicillin/clavulanic acid, gentamicin and trimethoprim. Among 300 patients from whom outcome was known, an association between the ST131-C2 lineage and longer length of stay was detected, although multivariable regression modelling did not demonstrate an association between E. coli ST and mortality. Several unexpected associations were identified between gentamicin non-susceptibility, ethnicity, sex and adverse outcomes, requiring further research.

CONCLUSIONS

Although E. coli ST was associated with defined antimicrobial non-susceptibility patterns and prolonged length of stay, E. coli ST was not associated with increased mortality. ST131 has outcompeted other lineages in north-west London. Where ST131 is prevalent, caution is required when devising empiric regimens for suspected Gram-negative sepsis, in particular the pairing of β-lactam agents with gentamicin.

Gram-negative bacteria act as a reservoir for aminoglycoside antibiotics that interact with host factors to enhance bacterial killing in a mouse model of pneumonia

In vitro exposure of multiple Gram-negative bacteria to an aminoglycoside (AG) antibiotic has previously been demonstrated to result in bacterial alterations that interact with host factors to suppress Gram-negative pneumonia. However, the mechanisms resulting in suppression are not known. Here, the hypothesis that Gram-negative bacteria bind and retain AGs, which are introduced into the lung and interact with host defenses to affect bacterial killing, was tested. Following in vitro exposure of one of several, pathogenic Gram-negative bacteria to the AG antibiotics kanamycin or gentamicin, AGs were detected in bacterial cell pellets (up to 208 μg/mL). Using inhibitors of AG binding and internalization, the bacterial outer membrane was implicated as the predominant kanamycin and gentamicin reservoir. Following intranasal administration of gentamicin-bound bacteria or gentamicin solution at the time of infection with live, AG-naïve bacteria, gentamicin was detected in the lungs of infected mice (up to 8 μg/g). Co-inoculation with gentamicin-bound bacteria resulted in killing of AG-naïve bacteria by up to 3-log10, mirroring the effects of intranasal gentamicin treatment. In vitro killing of AG-naïve bacteria mediated by kanamycin-bound bacteria required the presence of detergents or pulmonary surfactant, suggesting that increased bacterial killing inside the murine lung is facilitated by the detergent component of pulmonary surfactant. These findings demonstrate that Gram-negative bacteria bind and retain AGs that can interact with host-derived pulmonary surfactant to enhance bacterial killing in the lung. This may help explain why AGs appear to have unique efficacy in the lung and might expand their clinical utility.

The Comparative Effectiveness of Ceftolozane/Tazobactam versus Aminoglycoside- or Polymyxin-Based Regimens in Multi-Drug-Resistant Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa infections are challenging to treat due to multi-drug resistance (MDR) and the complexity of the patients affected by these serious infections. As new antibiotic therapies come on the market, limited data exist about the effectiveness of such treatments in clinical practice. In this comparative effectiveness study of ceftolozane/tazobactam versus aminoglycoside- or polymyxin-based therapies among hospitalized patients with positive MDR P. aeruginosa cultures, we identified 57 patients treated with ceftolozane/tazobactam compared with 155 patients treated with aminoglycoside- or polymyxin-based regimens. Patients treated with ceftolozane/tazobactam were younger (mean age 67.5 vs. 71.1, p = 0.03) and had a higher comorbidity burden prior to hospitalization (median Charlson 5 vs. 3, p = 0.01) as well as higher rates of spinal cord injury (38.6% vs. 21.9%, p = 0.02) and P. aeruginosa-positive bone/joint cultures (12.3% vs. 0.7%, p < 0.0001). Inpatient mortality was significantly lower in the ceftolozane/tazobactam group compared with aminoglycosides or polymyxins (15.8% vs. 27.7%, adjusted odds ratio 0.39, 95% confidence interval 0.16−0.93). There were no significant differences observed for the other outcomes assessed. In hospitalized patients with MDR P. aeruginosa, inpatient mortality was 61% lower among patients treated with ceftolozane/tazobactam compared to those treated with aminoglycoside- or polymyxin-based regimens.

Optimizing Doses of Ceftolozane/Tazobactam as Monotherapy or in Combination with Amikacin to Treat Carbapenem-Resistant Pseudomonas aeruginosa

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a hospital-acquired pathogen with a high mortality rate and limited treatment options. We investigated the activity of ceftolozane/tazobactam (C/T) and its synergistic effects with amikacin to extend the range of optimal therapeutic choices with appropriate doses. The E-test method is used to determine in vitro activity. The optimal dosing regimens to achieve a probability of target attainment (PTA) and a cumulative fraction of response (CFR) of ≥90% were simulated using the Monte Carlo method. Of the 66 CRPA isolates, the rate of susceptibility to C/T was 86.36%, with an MIC50 and an MIC90 of 0.75 and 24 µg/mL, respectively. Synergistic and additive effects between C/T and amikacin were observed in 24 (40%) and 18 (30%) of 60 CRPA isolates, respectively. The extended infusion of C/T regimens achieved a ≥90% PTA of 75% and a 100% fT > MIC at C/T MICs of 4 and 2 µg/mL, respectively. Only the combination of either a short or prolonged C/T infusion with a loading dose of amikacin of 20−25 mg/kg, followed by 15−20 mg/kg/day amikacin dosage, achieved ≥90% CFR. The C/T infusion, combined with currently recommended amikacin dose regimens, should be considered to manage CRPA infections.

Potential risks of treating bacterial infections with a combination of β-lactam and aminoglycoside antibiotics: A systematic quantification of antibiotic interactions in E. coli blood stream infection isolates

BACKGROUND

Treatment of Blood Stream Infections (BSIs) with a combination of a β-lactam and an aminoglycoside antibiotic is widely used in intensive care units (ICUs) around the world. However, no studies have systematically examined how these drugs interact and potentially influence the antimicrobial efficacy of the overall treatment.

METHODS

We collected 500 E. coli isolates from the Uppsala University hospital that were isolated from blood of patients with suspicion of infection. Of those we tested the efficacy of combinations of 2 common β-lactam antibiotics (Ampicillin and Cefotaxime) combined with 2 common aminoglycosides (Gentamicin and Tobramycin) on 254 isolates. The efficacy of all 4 pairwise combinations in inhibiting bacterial growth was then examined on all susceptible strains. That was done by quantifying the Fractional Inhibitory index (FICi), a robust metric for antibiotic combinatorial behaviour, of all possible treatments on every strain. When non additive interactions were identified, results of the original screen were verified with time kill assays. Finally, combination behaviours were analysed for potential cross correlations.

FINDINGS

Out of the 4 antibiotic combinations screened none exhibited synergistic effects on any of the 254 strains. On the contrary all 4 exhibited important antagonistic effects on several isolates. Specifically, the combinations of AMP-GEN and CTX-GEN were antagonistic in 1.97% and 1.18% of strains respectively. Similarly, the combinations of AMP-TOB were antagonistic on 0.78% of all strains. PCA analysis revealed that an important factor on the responses to the combination treatments was the choice of a specific aminoglycoside over another. Subsequent cross correlation analysis revealed that the interaction profiles of combinations including the same aminoglycoside are significantly correlated (Spearman's cross correlation test p<0.001).

INTERPRETATION

The findings of this study elucidate potential risks of the common combination treatment for blood stream infections. They also demonstrate, previously unquantified metrics on how antibiotics in combination therapies are not interchangeable with others of the same class. Finally, they reiterate the need for case-by-case testing of antibiotic interactions in a clinical setting.

FUNDING

This work was funded by grants to DIA from the Swedish Research Council, the Wallenberg foundation and the Swedish Strategic Research Foundation.

Relationship between amikacin pharmacokinetics and biological parameters associated with organ dysfunction: a case series study of critically ill patients with intra-abdominal sepsis

OBJECTIVES

This study aimed to evaluate the relationship between amikacin pharmacokinetics and the biomarkers associated with organ dysfunction in critically ill patients with intra-abdominal sepsis.

METHODS

A case series involving critically ill patients with intra-abdominal sepsis who received an amikacin loading dose of 20-25 mg/kg intravenous infusion was studied. The 1-, 2-, 4-, 6- and 24-hour amikacin serum concentrations were measured to calculate the pharmacokinetic parameters. The Sequential Organ Failure Assessment (SOFA) score, white blood cells, neutrophil to lymphocyte ratio, platelet count, serum creatinine, creatinine clearance, bilirubin, partial pressure of oxygen to fraction of inspired oxygen ratio, serum albumin, procalcitonin, lactate level, erythrocyte sedimentation rate (ESR) and C-reactive protein were recorded. A linear regression analysis was performed to examine the relationship between the amikacin pharmacokinetics and the biological parameters.

RESULTS

Twenty-one patients were studied. A significant correlation was found between the volume of distribution and ESR (p<0.05, r=0.844). Moreover, drug clearance had a significant inverse correlation with serum lactate (p<0.05, r=-0.603). No other significant correlations were found.

CONCLUSIONS

ESR and serum lactate were identified as useful predictors of amikacin pharmacokinetics in critically ill patients with intra-abdominal sepsis and may help guide the selection of appropriate empirical dosing.

A Cascaded Droplet Microfluidic Platform Enables High-Throughput Single Cell Antibiotic Susceptibility Testing at Scale

The global threat of antibiotic resistance underscores critical but unmet needs for rapid antibiotic susceptibility testing (AST) technologies. To this end, droplet microfluidic-based single-cell AST offers promise by achieving unprecedented rapidity, but its potential for clinical use is marred by the capacity of testing one to few antibiotic conditions per device, which falls short from the required scale in clinically relevant scenarios. To lift the scalability constraint in rapid single-cell AST technologies, a new cascaded droplet microfluidic platform that can streamline bacteria/antibiotic mixing, single-cell encapsulation within picoliter droplets, incubation, and detection in a continuous, assembly-line-like workflow is developed. The scalability of the platform is demonstrated by generating 32 groups of ≈10 000 droplets with custom antibiotic conditions within a single device, from which a new statistics-based method is used to analyze the single cell data and produce clinically useful antibiograms with minimum inhibitory concentrations in ≈90 min for the first antibiotic, plus 2 min for each subsequent antibiotic condition. Potential clinical utility of this platform is demonstrated by testing three clinical isolates and eight urine specimens against four frequently used antibiotics, and 100% and 93.8% categorical agreements are achieved compared to laboratory-based results that became available after 48 h.

OUP accepted manuscript

Background

Uncomplicated urinary tract infections (UTIs) are amongst the most frequent infections presenting in the outpatient setting. A growing number of clinical trials are assessing the most effective treatment interventions for uncomplicated UTI. Due to the heterogeneity of the outcomes reported in these trials, however, comparing these outcomes is challenging.

Objectives

Identify the core outcomes that have been reported in trials and systematic reviews of interventions treating uncomplicated UTI in adults.

Methods

We conducted a systematic search for core outcomes used to evaluate treatments of UTIs. We searched the Cochrane Database of Systematic Reviews, PubMed and Embase. One researcher independently screened each article for inclusion, and the Core Outcome Set for treatment of Urinary Tract Infections (COSUTI) team acted as second reviewers. All included articles were screened by two reviewers. All outcomes were extracted verbatim, and similar outcomes were grouped into domains and subdomains.

Results

In total, 334 outcomes were reported across 41 papers, the average number of outcomes reported being 8. Outcomes were categorized across 18 domains, the majority of which were related to clinical cure outcomes. Many outcomes varied in the timepoints within which the outcome was measured and reported.

Conclusions

Comparing the outcomes of trials investigating uncomplicated UTI treatment remains challenging due to the difference in outcomes currently reported. Consistency of reporting of outcomes would be improved by developing a minimum number of consistent outcomes that should be reported in all trials.

Aminoglycoside or Polymyxin Monotherapy for Treating Complicated Urinary Tract Infections Caused by Extensively Drug-Resistant Pseudomonas aeruginosa: A Propensity Score-Adjusted and Matched Cohort Study

INTRODUCTION

Extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA) infections are difficult to treat. We aimed to compare aminoglycosides or polymyxin monotherapy versus other antibiotic regimens (carbapenems, aztreonam, ceftazidime, cefepime, ceftolozane-tazobactam, or ceftazidime-avibactam) in complicated urinary tract infections (cUTI) caused by XDR-PA.

METHODS

Study performed at a tertiary-care hospital from 2010 to 2019. All consecutive adult patients with XDR-PA urine cultures and diagnosed with cUTI were retrospectively reviewed. XDR phenotype was defined according to Magiorakos et al. A propensity score was used as a covariate in multivariate analyses and for matching. Primary outcome was early clinical failure and at end of treatment (EOT). Main secondary outcomes were 30- and 90-day mortality, microbiological clearance, and antibiotic-related side effects.

RESULTS

Of the 465 episodes screened, 101 were included, 48% were treated with aminoglycoside or colistin monotherapy. Most XDR-PA were susceptible to colistin (100%) and amikacin (43%). Patients treated with antibiotic regimens other than aminoglycosides or polymyxin monotherapy were more likely to have hematologic malignancy (p < 0.001), higher SOFA score (p = 0.048), and bacteremia (p = 0.003). In multivariate models adjusted by propensity score, aminoglycoside or colistin monotherapy was not associated with worse outcomes. After propensity score matching, 28 episodes in each treatment group were matched. Adjusted ORs (95% CI) for early clinical failure and at EOT with aminoglycosides or polymyxin monotherapy were 0.53 (0.18-1.58) and 1.29 (0.34-4.83), respectively. Aminoglycoside or colistin monotherapy was not associated with higher 30-day (HR 0.93, 95% CI 0.17-5.08) or 90-day mortality (HR 0.68, 95% CI 0.20-2.31), nor with absence of microbiological clearance (OR 0.72, 95% CI 0.33-1.58). No statistically significant differences were found in terms of nephrotoxicity. Clostridioides difficile infection was observed only in the "other antibiotic regimens" group (n = 6, 11.3%).

CONCLUSIONS

Aminoglycosides or polymyxin monotherapy showed good efficacy and safety profile in treating cUTI caused by XDR-PA. These results may be useful for antibiotic stewardship activities.

A personalised approach to antibiotic pharmacokinetics and pharmacodynamics in critically ill patients

Critically ill patients admitted to intensive care unit (ICU) with severe infections, or those who develop nosocomial infections, have poor outcomes with substantial morbidity and mortality. Such patients commonly have suboptimal antibiotic exposures at routinely used antibiotic doses related to an increased volume of distribution and altered clearance due to their underlying altered physiology. Furthermore, the use of extracorporeal devices such as renal replacement therapy and extracorporeal membrane oxygenation in these group of patients also has the potential to alter in vivo drug concentrations. Moreover, ICU patients are likely to be infected with less-susceptible pathogens. Therefore, one potential contributing cause to the poor outcomes observed in critically ill patients may be related to subtherapeutic antibiotic exposures. Newer concepts include the clinician considering optimised dosing based on a blood antibiotic exposure defined by pharmacokinetic modelling and therapeutic drug monitoring, combined with a knowledge of the antibiotic penetration into the site of infection, thereby achieving optimal bacterial killing. Such optimised dosing is likely to improve patient outcomes. The aim of this review is to highlight key aspects of antibiotic pharmacokinetics and pharmacodynamics (PK/PD) in critically ill patients and provide a PK/PD approach to tailor antibiotic dosing to the individual patient.

Retrospective assessment of antimicrobial stewardship initiative in outpatient use of ertapenem for uncomplicated extended spectrum beta lactamase Enterobacteriaceae urinary tract infections

BACKGROUND

Urinary tract infections (UTI) are often over-diagnosed and over-treated, which can induce and select for resistant pathogens. After observing wide-spread outpatient use of ertapenem, a broad-spectrum antibiotic, a structured antimicrobial stewardship initiative (ASI) to improve appropriate antimicrobial prescribing was undertaken. ASI objectives were to achieve a goal of reducing ertapenem utilization for extended spectrum beta lactamase Enterobacteriaceae (ESBL-EB) UTI by 10% and evaluate the clinical outcomes associated with the ASI.

METHODS

A pre-to-post cohort study was conducted at a single-center integrated healthcare system between November 1, 2014 and February 26, 2017. An intensive, 90-day, pharmacist-driven, structured ASI was implemented between November 1, 2015 and January 29, 2016. Female patients aged ≥18 years who were treated for an uncomplicated, ESBL-EB urinary tract infection (UTI) were included. Primary outcome was clinical resolution defined as cure, persistence, relapse and recurrence. Secondary outcome measured was monthly ertapenem use expressed as number of days of therapy (DOT)/1000 adjusted patient days (APD). Segmented regression analysis for interrupted time series was performed to estimate ASI intervention effect.

RESULTS

A total of 184 patients were included in the study. Ertapenem utilization decreased from 0.0145 DOT/1000 APD in Nov. 2014 to 0.0078 DOT/1000 APD Feb. 2017(p < 0.01). The mean ertapenem DOT declined 19% overall from the pre vs. post intervention periods (32 vs 26, p < 0.01). Frequency of recurrent UTIs between treatments did not significantly differ and no adverse effects were reported in patients treated with aminoglycosides.

CONCLUSIONS

A structured ASI for uncomplicated ESBL-EB UTI was associated with a clinically meaningful decrease in ertapenem utilization and once-daily, 5-day aminoglycoside treatment was well-tolerated.

Effectiveness and safety of an institutional aminoglycoside-based regimen as empirical treatment of patients with pyelonephritis

OBJECTIVES

To determine clinical outcomes associated with aminoglycosides versus other antimicrobial agents as empirical treatment of hospitalized patients with pyelonephritis.

PATIENTS AND METHODS

An institutional programme promoting aminoglycosides as empirical treatment of pyelonephritis was implemented in 2016. We reviewed the hospital records of patients with pyelonephritis from January 2017 to April 2019. The primary outcome was death within 30 days of index culture. Initial treatment with aminoglycoside-based regimens was compared with non-aminoglycoside antibiotics. Propensity score matching was performed to adjust for between-group differences in baseline covariates.

RESULTS

The study cohort included 2026 patients, 715 treated with aminoglycosides and 1311 treated with non-aminoglycoside drugs (ceftriaxone, n = 774; piperacillin/tazobactam, n = 179; carbapenems, n = 161; and fluoroquinolones, n = 133); 589 patients (29%) had bloodstream infections. Treatment with aminoglycosides was associated with a higher likelihood of in vitro activity against clinical isolates (OR = 2.0; P < 0.001). Death at 30 days occurred in 55 (7.6%) versus 145 (11%) patients treated with aminoglycosides and non-aminoglycoside drugs, respectively (adjusted HR = 0.78; P = 0.013). Aminoglycosides were either superior or similar to comparator drugs in all patient subgroups, stratified according to age, glomerular filtration rate, bacteraemia, haemodynamic shock and infection with third-generation cephalosporin-resistant Enterobacteriaceae. The incidence of acute kidney injury was similar for aminoglycosides and comparators (2.5% versus 2.9%, respectively; P = 0.6).

CONCLUSIONS

Within the context of an institutional programme, initial empirical treatment of pyelonephritis with aminoglycosides was associated with higher rates of in vitro activity and lower overall mortality compared with non-aminoglycoside drugs, without excess nephrotoxicity.

Aminoglycoside versus carbapenem or piperacillin/tazobactam treatment for bloodstream infections of urinary source caused by Gram-negative ESBL-producing Enterobacteriaceae

OBJECTIVES

We studied the performance of aminoglycosides in treating bloodstream infections (BSIs) of urinary source caused by ESBL-producing Enterobacteriaceae (ESBL-EB).

METHODS

In a retrospective study of 193 patients with a clinical diagnosis of urinary tract infection, pyelonephritis or urosepsis and blood and urine cultures positive for ESBL-EB, patients were grouped according to whether they were treated with an aminoglycoside, a carbapenem or piperacillin/tazobactam. Multivariate analysis was used to define risk factors for mortality with inverse probability of treatment weighting used to minimize confounding. The primary efficacy outcome was 30 day mortality. The primary safety outcome was acute kidney injury (AKI) at 14 days.

RESULTS

Mean age was 79.3 years. Dementia, chronic kidney disease and the presence of a urinary catheter were common. Thirty-two (16.6%) patients died and risk factors for mortality included age, high Charlson score, presentation with severe sepsis/septic shock and infection with bacteria other than Escherichia coli. Aminoglycosides were non-inferior compared with other antibiotics regarding 30 day mortality [13.0% versus 21.2%, respectively; adjusted risk difference=10.29% (-0.82% to 21.41%)], but did not reach non-inferiority for bacteriuria recurrence [48.9% versus 44.7%, respectively; adjusted risk difference=-8.72% (-30.87% to 13.43%)]. AKI developed at a similar rate in both treatment groups: 12.0% versus 10.6%, respectively [OR=1.14 (0.46-2.81)]. Aminoglycosides were more efficacious in E. coli infections compared with other ESBL-EB.

CONCLUSIONS

We demonstrated the efficacy and safety of aminoglycosides in treating BSI of urinary source caused by ESBL-EB. This carbapenem-sparing approach can assist in avoiding excessive carbapenem use without compromising outcomes.

Epidemiology and Antimicrobial Susceptibility of Invasive Bacterial Infections in Children-A Population-Based Study From Norway

OBJECTIVE

To describe epidemiology and antimicrobial susceptibility testing (AST) data of bacteria causing invasive infections in Norwegian children (0-18 years).

METHODS

Population-based observational study using prospectively collected AST data from the Norwegian Surveillance System of Antimicrobial Resistance from 2013 to 2017. We included all clinically relevant bacterial isolates (blood and cerebrospinal fluid), and compared incidence of invasive infections and AST data in isolates from children and adults.

RESULTS

We included 1173 isolates from children and 44,561 isolates from adults. Staphylococcus aureus accounted for 220/477 (46.2%, 95% CI: 41.6-50.7) of all isolates in schoolchildren (6-18 years). Compared with Streptococcus pneumonia isolates from adults (N = 2674), we observed higher nonsusceptibility rates to penicillin in isolates from children (N = 151), 11.9% versus 5.8%, P < 0.01; also higher resistance rates to erythromycin (11.3% vs. 4.9%, P < 0.01), clindamycin (9.3% vs. 3.6%, P < 0.001), and trimethoprim/sulfamethoxazole (17.9% vs. 6.4%, P < 0.001). Compared with Escherichia coli isolates in adults (N = 9073), we found lower rates of ESBL in isolates from children (N = 212), 2.4% versus 6.4%, P < 0.05.

CONCLUSION

The study indicates the importance of microbiologic surveillance strategies in children and highlights the need for pediatric AST data. The high rates of nonsusceptibility to commonly used antibiotics among S. pneumoniae in children and the high burden of invasive S. aureus infections in schoolchildren calls for modifications of Norwegian guidelines.

Impact of the Epithelial Lining Fluid Milieu on Amikacin Pharmacodynamics Against Pseudomonas aeruginosa

Background

Even though nebulised administration of amikacin can achieve high epithelial lining fluid concentrations, this has not translated into improved patient outcomes in clinical trials. One possible reason is that the cellular and chemical composition of the epithelial lining fluid may inhibit amikacin-mediated bacterial killing.

Objective

The objective of this study was to identify whether the epithelial lining fluid components inhibit amikacin-mediated bacterial killing.

Methods

Two amikacin-susceptible (minimum inhibitory concentrations of 2 and 8 mg/L) Pseudomonas aeruginosa isolates were exposed in vitro to amikacin concentrations up to 976 mg/L in the presence of an acidic pH, mucin and/or surfactant as a means of simulating the epithelial lining fluid, the site of bacterial infection in pneumonia. Pharmacodynamic modelling was used to describe associations between amikacin concentrations, bacterial killing and emergence of resistance.

Results

In the presence of broth alone, there was rapid and extensive (> 6 − log₁₀) bacterial killing, with emergence of resistance identified in amikacin concentrations < 976 mg/L. In contrast, the rate and extent of bacterial killing was reduced (≤ 5 − log₁₀) when exposed to an acidic pH and mucin. Surfactant did not appreciably impact the bacterial killing or resistance emergence when compared with broth alone for either isolate. The combination of mucin and an acidic pH further reduced the rate of bacterial killing, with the maximal bacterial killing occurring 24 h following initial exposure compared with approximately 4–8 h for either mucin or an acidic pH alone.

Conclusions

Our findings indicate that simulating the epithelial lining fluid antagonises amikacin-mediated killing of P. aeruginosa, even at the high concentrations achieved following nebulised administration.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40268-021-00344-5.

Ceftolozane/Tazobactam vs Polymyxin or Aminoglycoside-based Regimens for the Treatment of Drug-resistant Pseudomonas aeruginosa

BACKGROUND

Ceftolozane/tazobactam is a novel cephalosporin/beta-lactamase inhibitor combination that often retains activity against resistant Pseudomonas aeruginosa. The comparative safety and efficacy vs polymyxins or aminoglycosides in this setting remains unknown.

METHODS

A retrospective, multicenter, observational cohort study was performed. Patients who received ceftolozane/tazobactam were compared with those treated with either polymyxin or aminoglycoside-based regimens for infections due to drug-resistant P. aeruginosa. Multivariate logistic regression was performed controlling for factors associated with treatment to assess the independent impact of ceftolozane/tazobactam on clinical cure, acute kidney injury (AKI), and in-hospital mortality.

RESULTS

A total of 200 patients were included (100 in each treatment arm). The cohort represented an ill population with 69% in the intensive care unit, 63% mechanically ventilated, and 42% in severe sepsis or septic shock at infection onset. The most common infection type was ventilator-associated pneumonia (52%); 7% of patients were bacteremic. Combination therapy was more commonly used in polymyxin/aminoglycoside patients than those who received ceftolozane/tazobactam (72% vs 15%, P < .001). After adjusting for differences between groups, receipt of ceftolozane/tazobactam was independently associated with clinical cure (adjusted odds ratio [aOR], 2.63; 95% confidence interval [CI], 1.31-5.30) and protective against AKI (aOR, 0.08; 95% CI, 0.03-0.22). There was no difference in in-hospital mortality. The number needed to treat for a clinical cure with ceftolozane/tazobactam was 5, and the number needed to harm with AKI with a polymyxin/aminoglycoside was 4.

CONCLUSIONS

These data support the preferential use of ceftolozane/tazobactam over polymyxins or aminoglycosides for drug-resistant P. aeruginosa infections.

CON: Carbapenems are NOT necessary for all infections caused by ceftriaxone-resistant Enterobacterales

Carbapenems are considered the drugs of choice for the treatment of serious infections caused by ceftriaxone-resistant Enterobacterales. However, because of the dramatic increase in carbapenem-resistant organisms worldwide, finding alternatives to carbapenems is a must. The potential options include β-lactam/β-lactamase inhibitor combinations, temocillin, cephamycins and some non-β-lactam drugs. The most controversial is piperacillin/tazobactam; the results of the MERINO trial are challenged because the isolates of patients with worse outcomes were frequently not susceptible to piperacillin/tazobactam when studied by reference methods, and also because the drug was not administered in extended infusion. Other potential options are briefly discussed. We conclude that carbapenems are not necessary for all patients with infections caused by ceftriaxone-resistant Enterobacterales.

Significant Publications on Infectious Diseases Pharmacotherapy in 2019

PURPOSE

To provide a summary of the most prominent peer-reviewed infectious diseases (ID) pharmacotherapy and Human Immunodeficiency Virus (HIV)-related articles published in 2019.

SUMMARY

Houston Infectious Diseases Network (HIDN) members were asked to nominate articles that they believed were most influential within the ID and HIV pharmacotherapy science communities. A total of 48 general ID and 6 HIV-related articles were nominated. Following nominations, an online survey was distributed via e-mail to Society of Infectious Diseases Pharmacists (SIDP) members, with a total of 156 and 54 members voting for general ID and HIV-related articles, respectively. The results of this survey were ranked to determine the top 10 general ID and top HIV articles. The top articles were then summarized by HIDN members, including residents, fellows, and clinical pharmacists.

CONCLUSION

This review covers many of the most influential ID articles published in 2019, including 3 practice guideline updates. Due to the high rate of ID literature published each year, this review continues to help summarize these articles for the ID community, allowing clinicians to remain up-to-date on practice-changing publications in ID and HIV pharmacotherapy.

Optimizing therapy of bloodstream infection due to extended-spectrum β-lactamase-producing Enterobacteriaceae

PURPOSE OF REVIEW

Infections due to extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are increasing worldwide. Carbapenems are usually regarded as the antibiotics of choice for the treatment of serious ESBL infections. However, because of the alarming emergence or carbapenem resistance, interest in effective alternatives has emerged. The present review summarizes the findings published on the antibiotics currently available for treatment of patients with an ESBL-E bloodstream infection (BSI).

RECENT FINDINGS

Meropenem and imipenem are the drugs recommended for treatment of ESBL BSIs in critically ill patients, and in infections with high bacterial loads or elevated β-lactam minimum inhibitory concentrations. Ertapenem should be reserved for patients with less severe presentations, and should be used at high doses. In milder presentations or BSIs from low-risk sources, other carbapenem-sparing alternatives could be considered: cephamycins, fluoroquinolones, and particularly a β-lactam/β-lactam inhibitor combination (particularly piperacillin/tazobactam). Optimized dosing of piperacillin/tazobactam is recommended (high doses and extended infusion). There are few data on the use of the promising newly available drugs (e.g. ceftolozane/tazobactam, ceftazidime/avibactam, cefiderocol, and plazomicin), and it seems reasonable to reserve them as last-resort drugs.

SUMMARY

Carbapenems should be used in patients with serious infections; alternatives could be used individually, particularly for definitive treatment of patients with milder presentations.

Experience With Ceftolozane-Tazobactam for the Treatment of Serious Pseudomonas aeruginosa Infections in Saudi Tertiary Care Center

Introduction:

Multidrug-resistant Pseudomonas aeruginosa isolates have multiple resistance mechanisms, and there are insufficient therapeutic options to target them. Ceftolozane-tazobactam is a novel antipseudomonal agent that contains a combination of an oxyimino-aminothiazolyl cephalosporin (ceftolozane) and a β-lactamase inhibitor (tazobactam).

Methods:

A single-center retrospective observational study between January 2017 and December 2018 for patients who had been diagnosed with carbapenem-resistant P aeruginosa infections and treated with ceftolozane-tazobactam for more than 72 hours. We assessed clinical success based on microbiological clearance as well as the clinical resolution of signs and symptoms of infection.

Results:

A total of 19 patients fit the inclusion criteria, with a median age was 57 years, and 53% were female. The types of infections were nosocomial pneumonia, acute bacterial skin, and skin structure infections; complicated intra-abdominal infections; and central line–associated bloodstream infections. All of the isolates were resistant to both meropenem and imipenem. The duration of therapy was variable (average of 14 days). At day 14 of starting ceftolozane-tazobactam, 18 of 19 patients had a resolution of signs and symptoms of the infection. Only 14 of 19 patients (74%) had proven microbiological eradication observed at the end of therapy. During therapy, there was no adverse event secondary to ceftolozane-tazobactam, and no Clostridium difficile infection was identified. The 30-day mortality rate was 21% (4/19).

Conclusions:

Multidrug-resistant P aeruginosa infection is associated with high mortality, which would potentially be improved using a new antibiotic such as ceftolozane-tazobactam. Studies are required to explain the role of combination therapy, define adequate dosing, and identify the proper duration of treatment.

Carbapenem-Sparing Strategies for ESBL Producers: When and How

Extended spectrum β-lactamase (ESBL)-producing bacteria are prevalent worldwide and correlated with hospital infections, but they have been evolving as an increasing cause of community acquired infections. The spread of ESBL constitutes a major threat for public health, and infections with ESBL-producing organisms have been associated with poor outcomes. Established therapeutic options for severe infections caused by ESBL-producing organisms are considered the carbapenems. However, under the pressure of carbapenem overuse and the emergence of resistance, carbapenem-sparing strategies have been implemented. The administration of carbapenem-sparing antibiotics for the treatment of ESBL infections has yielded conflicting results. Herein, the current available knowledge regarding carbapenem-sparing strategies for ESBL producers is reviewed, and the optimal conditions for the "when and how" of carbapenem-sparing agents is discussed. An important point of the review focuses on piperacillin-tazobactam as the agent arousing the most debate. The most available data regarding non-carbapenem β-lactams (i.e., ceftolozane-tazobactam, ceftazidime-avibactam, temocillin, cephamycins and cefepime) are also thoroughly presented as well as non β-lactams (i.e., aminoglycosides, quinolones, tigecycline, eravacycline and fosfomycin).

Early diagnosis of bloodstream infections in the intensive care unit using machine-learning algorithms

PURPOSE

We aimed to develop a machine-learning (ML) algorithm that can predict intensive care unit (ICU)-acquired bloodstream infections (BSI) among patients suspected of infection in the ICU.

METHODS

The study was based on patients' electronic health records at Beth Israel Deaconess Medical Center (BIDMC) in Boston, Massachusetts, USA, and at Rambam Health Care Campus (RHCC), Haifa, Israel. We included adults from whom blood cultures were collected for suspected BSI at least 48 h after admission. Clinical data, including time-series variables and their interactions, were analyzed by an ML algorithm at each site. Prediction ability for ICU-acquired BSI was assessed by the area under the receiver operating characteristics (AUROC) of ten-fold cross-validation and validation sets with 95% confidence intervals.

RESULTS

The datasets comprised 2351 patients from BIDMC (151 with BSI) and 1021 from RHCC (162 with BSI). The median (inter-quartile range) age was 62 (51-75) and 56 (38-69) years, respectively; the median Acute Physiology and Chronic Health Evaluation II scores were 26 (21-32) and 24 (20-29), respectively. The means of the cross-validation AUROCs were 0.87 ± 0.02 for BIDMC and 0.93 ± 0.03 for RHCC. AUROCs of 0.89 ± 0.01 and 0.92 ± 0.02 were maintained in both centers with internal validation, while external validation deteriorated. Valuable predictors were mainly the trends of time-series variables such as laboratory results and vital signs.

CONCLUSION

An ML approach that uses temporal and site-specific data achieved high performance in recognizing BC samples with a high probability for ICU-acquired BSI.

Rational approach in the management of Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

This review details the management of Pseudomonas aeruginosa infections covering both current and future treatment options that are and may be available for the clinicians.

RECENT FINDINGS

Pseudomonas aeruginosa infections are a great concern in hospital-acquired infections with very limited therapeutic options. The increasing antibiotic resistance has led to a need for different treatment choices that range from the use of new antibiotics to new nonantibiotic alternative agents to kill or disarm the pathogen.

SUMMARY

New molecules such as ceftolozane-tazobactam, ceftazidime-avibactam, and imipenem-relebactam have shown an adequate activity against P. aeruginosa, especially against multidrug resistance strains. Other nonantibiotic alternative treatments, such as antibodies, bacteriocins or phage therapy, have shown promising results, but future clinical studies are needed.

Aminoglycoside Allergic Reactions

Aminoglycosides are antimicrobial agents that are primarily used for infections caused by Gram-negative pathogens. The purpose of this article is to review the allergic reactions reported in the published literature to aminoglycoside antibiotics. A thorough PubMed search was conducted and excluded non-allergic adverse reactions to aminoglycosides. Allergic reactions to aminoglycosides occur infrequently, but can include cutaneous reactions as well as systemic reactions, including anaphylaxis. Of the evaluated aminoglycosides, gentamicin had the most reported allergic reactions, including the most reports of anaphylaxis, followed by tobramycin, and then amikacin. Most reports of allergic reactions occurred in patients who had a prior exposure to some dosage form of an aminoglycoside. Cross-reactivity among aminoglycosides is common and occurs due to the similarities in their chemical structures. Desensitization protocols to tobramycin have been described in the literature.

The "Old" and the "New" Antibiotics for MDR Gram-Negative Pathogens: For Whom, When, and How

The recent expansion of multidrug resistant and pan-drug-resistant pathogens poses significant challenges in the treatment of healthcare associated infections. An important advancement, is a handful of recently launched new antibiotics targeting some of the current most problematic Gram-negative pathogens, namely carbapenem-producing Enterobacteriaceae (CRE) and carbapenem-resistant P. aeruginosa (CRPA). Less options are available against carbapenem-resistant Acinetobacter baumannii (CRAB) and strains producing metallo-beta lactamases (MBL). Ceftazidime-avibactam signaled a turning point in the treatment of KPC and partly OXA- type carbapenemases, whereas meropenem-vaborbactam was added as a potent combination against KPC-producers. Ceftolozane-tazobactam could be seen as an ideal beta-lactam backbone for the treatment of CRPA. Plazomicin, an aminoglycoside with better pharmacokinetics and less toxicity compared to other class members, will cover important proportions of multi-drug resistant pathogens. Eravacycline holds promise in the treatment of infections by CRAB, with a broad spectrum of activity similar to tigecycline, and improved pharmacokinetics. Novel drugs and combinations are not to be considered "panacea" for the ongoing crisis in the therapy of XDR Gram-negative bacteria and colistin will continue to be considered as a fundamental companion drug for the treatment of carbapenem-resistant Enterobacteriaceae (particularly in areas where MBL predominate), for the treatment of CRPA (in many cases being the only in vitro active drug) as well as CRAB. Aminoglycosides are still important companion antibiotics. Finally, fosfomycin as part of combination treatment for CRE infections and P. aeruginosa, deserves a greater attention. Optimal conditions for monotherapy and the "when and how" of combination treatments integrating the novel agents will be discussed.

Current options for the treatment of infections due to extended-spectrum beta-lactamase-producing Enterobacteriaceae in different groups of patients

BACKGROUND

Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are a frequent cause of invasive infections worldwide. Carbapenems are nowadays the most used drugs to treat these infections. However, due to the increasing rates of resistance to these antimicrobials, carbapenem-sparing alternatives are being investigated.

OBJECTIVES AND SOURCES

The aim of this narrative literature review is to summarize the published information on the currently available antibiotics for the treatment of ESBL-E infections, providing specific information on three subgroups of patients: Group 1, patients with severe infections or infections from high-risk sources or in severely immunocompromised patients; Group 2, patients with non-severe infections from intermediate-risk source; and Group 3, patients with non-severe urinary tract infection.

CONTENT AND IMPLICATIONS

For patients in Group 1, the current data would support the use of carbapenems. For milder infections, however, particularly urinary tract infections, other non-carbapenem antibiotics can be considered in selected cases, including beta-lactam/beta-lactam inhibitor combinations, cephamycins, temocillin and aminoglycosides. While specific studies should be performed in these situations, individualized decisions may be taken in order to avoid overuse of carbapenems.

Lower ototoxicity and absence of hidden hearing loss point to gentamicin C1a and apramycin as promising antibiotics for clinical use

Spread of antimicrobial resistance and shortage of novel antibiotics have led to an urgent need for new antibacterials. Although aminoglycoside antibiotics (AGs) are very potent anti-infectives, their use is largely restricted due to serious side-effects, mainly nephrotoxicity and ototoxicity. We evaluated the ototoxicity of various AGs selected from a larger set of AGs on the basis of their strong antibacterial activities against multidrug-resistant clinical isolates of the ESKAPE panel: gentamicin, gentamicin C1a, apramycin, paromomycin and neomycin. Following local round window application, dose-dependent effects of AGs on outer hair cell survival and compound action potentials showed gentamicin C1a and apramycin as the least toxic. Strikingly, although no changes were observed in compound action potential thresholds and outer hair cell survival following treatment with low concentrations of neomycin, gentamicin and paromomycin, the number of inner hair cell synaptic ribbons and the compound action potential amplitudes were reduced. This indication of hidden hearing loss was not observed with gentamicin C1a or apramycin at such concentrations. These findings identify the inner hair cells as the most vulnerable element to AG treatment, indicating that gentamicin C1a and apramycin are promising bases for the development of clinically useful antibiotics.

Prediction of bloodstream infection caused by extended-spectrum β-lactamase-producing Enterobacterales in patients with suspected community-onset sepsis

OBJECTIVES

In severe infections, time to appropriate therapy is decisive for survival. Patients with bloodstream infection caused by extended-spectrum β-lactamase-producing Enterobacterales (EPE-BSI) often receive inadequate empirical treatment. This study aimed to identify risk factors, to evaluate a previously suggested risk score and to suggest a new score for facilitating empirical treatment choice.

METHODS

Predictors for EPE-BSI were assessed through a retrospective case-control design. The diagnostic performance of the two scores was evaluated. Included patients had blood cultures sampled at four EDs in Stockholm (2012-2015), were admitted, and received antibiotics with activity against Gram-negative bacilli.

RESULTS

A total of 277 EPE-BSI cases and 400 controls were included. The strongest predictor of EPE-BSI was prior EPE-positive culture (cases 33% vs. controls 3%; multivariate (MV) OR = 19.1). Recent EPE-positivity within ≤3 months had a univariate OR of 32.8. Other major predictors were recent prostate biopsy (14% vs. 1%; MV OR = 22.2) and healthcare abroad (6% vs. 2%; MV OR = 3.9). Several previously suggested risk factors were not associated with EPE-BSI. The previously developed Utrecht score had a sensitivity of 54% and a specificity of 77%. The Stockholm score suggested herein (prior EPE-positive culture/prostate biopsy/healthcare abroad) showed comparable sensitivity (50%) but better specificity (96%). Prediction in patients lacking major predictors was difficult and caused high false-positive rates, which would cause unnecessary overtreatment.

CONCLUSIONS

Prior EPE-positive culture, especially recently sampled, prostate biopsy and healthcare abroad were the strongest risk factors for community-onset EPE-BSI in Stockholm. Local data are needed when evaluating risk-scoring models before implementation.

Outcomes of empiric aminoglycoside monotherapy for Pseudomonas aeruginosa bacteremia

We evaluated 30-day mortality in patients with Pseudomonas aeruginosa bacteremia. There was no significant difference in mortality among patients who received functional aminoglycoside monotherapy versus inappropriate empiric therapy. Among patients given appropriate empiric therapy, functional aminoglycoside monotherapy was associated with less favorable outcomes compared to beta-lactam monotherapy.

Ceftolozane-Tazobactam for the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Infections: A Multicenter Study

Background

Multidrug-resistant Pseudomonas aeruginosa infections remain common in hospitals worldwide. We investigated the outcomes associated with the use of ceftolozane-tazobactam for the treatment of these infections.

Methods

Data were collected retrospectively from 20 hospitals across the United States about adults who received ceftolozane-tazobactam for the treatment of multidrug-resistant P aeruginosa infections of any source for at least 24 hours. The primary outcome was a composite of 30-day and inpatient mortality, and secondary outcomes were clinical success and microbiological cure. Multivariable regression analysis was conducted to determine factors associated with outcomes.

Results

Two-hundred five patients were included in the study. Severe illness and high degrees of comorbidity were common, with median Acute Physiology and Chronic Health Evaluation (APACHE) II scores of 19 (interquartile range [IQR], 11–24) and median Charlson Comorbidity Indexes of 4 (IQR, 3–6). Delayed initiation of ceftolozane-tazobactam was common with therapy started a median of 9 days after culture collection. Fifty-nine percent of patients had pneumonia. On susceptibility testing, 125 of 139 (89.9%) isolates were susceptible to ceftolozane-tazobactam. Mortality occurred in 39 patients (19%); clinical success and microbiological cure were 151 (73.7%) and 145 (70.7%), respectively. On multivariable regression analysis, starting ceftolozane-tazobactam within 4 days of culture collection was associated with survival (adjusted odds ratio [OR], 5.55; 95% confidence interval [CI], 2.14–14.40), clinical success (adjusted OR, 2.93; 95% CI, 1.40–6.10), and microbiological cure (adjusted OR, 2.59; 95% CI, 1.24–5.38).

Conclusions

Ceftolozane-tazobactam appeared to be effective in the treatment of multidrug-resistant P aeruginosa infections, particularly when initiated early after the onset of infection.

Spatiotemporal pharmacodynamics of meropenem- and tobramycin-treated Pseudomonas aeruginosa biofilms

Objectives

The selection and dose of antibiotic therapy for biofilm-related infections are based on traditional pharmacokinetic studies using planktonic bacteria. The objective of this study was to characterize the time course and spatial activity of human exposure levels of meropenem and tobramycin against Pseudomonas aeruginosa biofilms grown in an in vitro flow-chamber model.

Methods

Pharmacokinetic profiles of meropenem and tobramycin used in human therapy were administered to GFP-labelled P. aeruginosa PAO1 grown in flow chambers for 24 or 72 h. Images were acquired using confocal laser scanning microscopy throughout antibiotic treatment. Bacterial biomass was measured using COMSTAT and pharmacokinetic/pharmacodynamic models were fitted using NONMEM7.

Results

Meropenem treatment resulted in more rapid and sustained killing of both the 24 and 72 h PAO1 biofilm compared with tobramycin. Biofilm regrowth after antibiotic treatment occurred fastest with tobramycin. Meropenem preferentially killed subpopulations within the mushroom cap of the biofilms, regardless of biofilm maturity. The spatial killing by tobramycin varied with biofilm maturity. A tobramycin-treated 24 h biofilm resulted in live and dead cells detaching from the biofilm, while treatment of a 72 h biofilm preferentially killed subpopulations on the periphery of the mushroom stalk. Regrowth occurred primarily on the mushroom caps. Combination meropenem and tobramycin therapy resulted in rapid and efficient killing of biofilm cells, with a spatial pattern similar to meropenem alone.

Conclusions

Simulated human concentrations of meropenem and tobramycin in young and mature PAO1 biofilms exhibited differences in temporal and spatial patterns of killing and antibiotic tolerance development.

Stopping the effective non-fluoroquinolone antibiotics at day 7 vs continuing until day 14 in adults with acute pyelonephritis requiring hospitalization: A randomized non-inferiority trial

Objective

To evaluate whether stopping the effective antibiotic treatment following clinical improvement at Day 7 (Truncated treatment) would be non-inferior to continued treatment until Day 14 (Continued treatment) in patients with acute pyelonephritis (APN) requiring hospitalization treated with non-fluoroquinolone (non-FQ) antibiotics.

Methods

Hospitalized adult men and non-pregnant women with culture-confirmed APN were eligible for participation after they had clinically improved following empirical or culture-guided treatment with intravenous non-FQ antibiotic(s). We excluded patients with severe sepsis, abscesses, prostatitis, recurrent or catheter-associated urinary tract infection, or urinary tract obstruction. We randomized eligible patients on Day 7 of effective treatment and assessed them at Weeks 1 and 6 after treatment completion. The primary outcome was retreatment for recurrent urinary tract infection. The prespecified non-inferiority margin was 15%.

Results

Between March 17, 2015 and August 22, 2016, we randomly allocated 54 patients—27 patients in each arm. Twenty-four (44%) patients were male, and 26 (48%) had diabetes mellitus. Escherichia coli was the most common urinary isolate (47 [87%] patients); 36 (78%) were resistant to ciprofloxacin. In all, 41 (76%) patients received amikacin-based treatment. At the end of 6 weeks, no patient in the truncated treatment arm required retreatment, whereas 1 patient in the continued treatment arm was retreated. Difference (90% CI) in retreatment was −3.7% (−15.01% to 6.15%). Upper bound of the difference (6.15%) was below the prespecified limit, establishing non-inferiority of truncated treatment. Asymptomatic bacteriuria at Week 6 was similar between the two arms (3/24 vs. 3/26; P = 1.0). Patients in the truncated treatment arm had significantly shorter hospital stay (8 [7–10] vs. 14 [14–15] days; P < 0.001) and less antibiotic consumption per patient (8.4 ± 2.8 vs. 17.4 ± 8.3 DDDs; P < 0.001).

Conclusion

Stopping the effective non-FQ antibiotics following clinical improvement at Day 7 is non-inferior to continued treatment until Day 14 in selected patients with APN requiring hospitalization.

Trial registration

Clinical Trials Registry-India; CTRI/2016/04/006810.

Sparing carbapenem usage

Background

Carbapenem resistance in Gram-negative bacteria is increasing in many countries and use of carbapenems and antibiotics to which resistance is linked should be reduced to slow its emergence. There are no directly equivalent antibiotics and the alternatives are less well supported by clinical trials. The few new agents are expensive.

Objectives

To provide guidance on strategies to reduce carbapenem usage.

Methods

A literature review was performed as described in the BSAC/HIS/BIA/IPS Joint Working Party on Multiresistant Gram-negative Infection Report.

Results

Older agents remain active against some of the pathogens, although expectations of broad-spectrum cover for empirical treatment have risen. Education, expert advice on treatment and antimicrobial stewardship can produce significant reductions in use.

Conclusions

More agents may need to be introduced onto the antibiotic formulary of the hospital, despite the poor quality of scientific studies in some cases.

A Multicenter, Randomized, Double-Blind, Phase 2 Study of the Efficacy and Safety of Plazomicin Compared with Levofloxacin in the Treatment of Complicated Urinary Tract Infection and Acute Pyelonephritis

Increasing antimicrobial resistance among uropathogens limits treatment options for patients with complicated urinary tract infection (cUTI). Plazomicin, a new aminoglycoside, has in vitro activity against multidrug-resistant Enterobacteriaceae, including isolates resistant to currently available aminoglycosides, as well as extended-spectrum β-lactamase-producing and carbapenem-resistant Enterobacteriaceae. We evaluated the efficacy and safety of plazomicin in a double-blind, comparator-controlled, phase 2 study in adults with cUTI or acute pyelonephritis. Patients were randomized 1:1:1 to receive intravenous plazomicin (10 or 15 mg/kg of body weight) or intravenous levofloxacin (750 mg) once daily for 5 days. Coprimary efficacy endpoints were microbiological eradication at the test of cure (TOC; 5 to 12 days after the last dose) in the modified intent-to-treat (MITT) and microbiologically evaluable (ME) populations. Overall, 145 patients were randomized to treatment. In the groups receiving plazomicin at 10 mg/kg, plazomicin at 15 mg/kg, and levofloxacin, microbiological eradication rates were, respectively, 50.0% (6 patients with microbiological eradication at TOC/12 patients treated [95% confidence interval {CI}, 21.1 to 78.9%]), 60.8% (31/51 [95% CI, 46.1 to 74.2%]), and 58.6% (17/29 [95% CI, 38.9 to 76.5%]) in the MITT population and 85.7% (6/7 [95% CI, 42.1 to 99.6%]), 88.6% (31/35 [95% CI, 73.3 to 96.8%]), and 81.0% (17/21 [95% CI, 58.1 to 94.6%]) in the ME population. In the MITT population, 66.7% (95% CI, 34.9 to 90.1%), 70.6% (95% CI, 56.2 to 82.5%), and 65.5% (95% CI, 45.7 to 82.1%) of the patients in the three groups, respectively, were assessed by the investigator to be clinically cured at TOC. Adverse events were reported in 31.8%, 35.1%, and 47.7% of the patients in the three groups, respectively. Serum creatinine values were generally stable over the course of the study. No plazomicin-treated patients with evaluable audiometry data had postbaseline sensorineural, conductive, or mixed hearing loss. In summary, plazomicin demonstrated microbiological and clinical success and an overall safety profile supportive of further clinical development. (This study has been registered at ClinicalTrials.gov under identifier NCT01096849.)

Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam-β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some "second-line" drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.