Ceftolozane-Tazobactam Combination Therapy Compared to Ceftolozane-Tazobactam Monotherapy for the Treatment of Severe Infections: A Systematic Review and Meta-Analysis

Rationale and evidence for the use of new beta-lactam/beta-lactamase inhibitor combinations and cefiderocol in critically ill patients

BACKGROUND

Healthcare-associated infections involving Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) phenotype are associated with impaired patient-centered outcomes and poses daily therapeutic challenges in most of intensive care units worldwide. Over the recent years, four innovative β-lactam/β-lactamase inhibitor (BL/BLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam) and a new siderophore cephalosporin (cefiderocol) have been approved for the treatment of certain DTR-GNB infections. The literature addressing their microbiological spectrum, pharmacokinetics, clinical efficacy and safety was exhaustively audited by our group to support the recent guidelines of the French Intensive Care Society on their utilization in critically ill patients. This narrative review summarizes the available evidence and unanswered questions on these issues.

METHODS

A systematic search for English-language publications in PUBMED and the Cochrane Library database from inception to November 15, 2022.

RESULTS

These drugs have demonstrated relevant clinical success rates and a reduced renal risk in most of severe infections for whom polymyxin- and/or aminoglycoside-based regimen were historically used as last-resort strategies-namely, ceftazidime-avibactam for infections due to Klebsiella pneumoniae carbapenemase (KPC)- or OXA-48-like-producing Enterobacterales, meropenem-vaborbactam for KPC-producing Enterobacterales, ceftazidime-avibactam/aztreonam combination or cefiderocol for metallo-β-lactamase (MBL)-producing Enterobacterales, and ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam for non-MBL-producing DTR Pseudomonas aeruginosa. However, limited clinical evidence exists in critically ill patients. Extended-infusion scheme (except for imipenem-relebactam) may be indicated for DTR-GNB with high minimal inhibitory concentrations and/or in case of augmented renal clearance. The potential benefit of combining these agents with other antimicrobials remains under-investigated, notably for the most severe presentations. Other important knowledge gaps include pharmacokinetic information in particular situations (e.g., pneumonia, other deep-seated infections, and renal replacement therapy), the hazard of treatment-emergent resistance and possible preventive measures, the safety of high-dose regimen, the potential usefulness of rapid molecular diagnostic tools to rationalize their empirical utilization, and optimal treatment durations. Comparative clinical, ecological, and medico-economic data are needed for infections in whom two or more of these agents exhibit in vitro activity against the causative pathogen.

CONCLUSIONS

New BL/BLI combinations and cefiderocol represent long-awaited options for improving the management of DTR-GNB infections. Several research axes must be explored to better define the positioning and appropriate administration scheme of these drugs in critically ill patients.

Burden of severe infections due to carbapenem-resistant pathogens in intensive care unit

Intensive care units (ICU) for various reasons, including the increasing age of admitted patients, comorbidities, and increasingly complex surgical procedures (e.g., transplants), have become "the epicenter" of nosocomial infections, these are characterized by the presence of multidrug-resistant organisms (MDROs) as the cause of infection. Therefore, the perfect match of fragile patients and MDROs, as the cause of infection, makes ICU mortality very high. Furthermore, carbapenems were considered for years as last-resort antibiotics for the treatment of infections caused by MDROs; unfortunately, nowadays carbapenem resistance, mainly among Gram-negative pathogens, is a matter of the highest concern for worldwide public health. This comprehensive review aims to outline the problem from the intensivist's perspective, focusing on the new definition and epidemiology of the most common carbapenem-resistant MDROs (Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacterales) to emphasize the importance of the problem that must be permeating clinicians dealing with these diseases.

Satisfactory In Vitro Activity of Ceftolozane–Tazobactam against Carbapenem-Resistant Pseudomonas aeruginosa But Not against Klebsiella pneumoniae Isolates

Background: Gram-negative rods are one of the most commonly isolated bacteria within human infections. These microorganisms are typically opportunistic pathogens that pose a serious threat to public health due to the possibility of transmission in the human population. Resistance to carbapenems is one of the most important antimicrobial resistance mechanisms amongst them. The aim of this study was to evaluate ceftolozane–tazobactam in vitro activity against carbapenem-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae clinical strains. Information on the antimicrobial activity of this antimicrobial against Gram-negative rods was also supplemented with a brief review of the relevant literature. Methods: The research involved 316 strains of Gram-negative rods: P. aeruginosa—206 and K. pneumoniae—110. Results: Of the tested strains, 86.0% P. aeruginosa and 30.0% K. pneumoniae remained susceptible to ceftolozane–tazobactam. Conclusions: Therefore, ceftolozane–tazobactam might be a good option in the treatment of infections caused by carbapenem-resistant P. aeruginosa strains, including those in ICU patients. Meanwhile, due to dissemination of ESBLs among K. pneumoniae strains, infections with this etiology should not be treated with the ceftolozane–tazobactam combination.

The efficacy and safety of ceftolozane-tazobactam in the treatment of GNB infections: a systematic review and meta-analysis of clinical studies

BACKGROUND

Ceftolozane-tazobactam is a novel cephalosporin/β-lactamase inhibitor combination with activity against Gram-negative bacteria (GNB). We aimed to comprehensively evaluate the clinical efficacy and safety of ceftolozane-tazobactam in treating GNB infections in adult patients.

RESEARCH DESIGN AND METHODS

PubMed, Embase, and Cochrane databases were retrieved until August 2022. Randomized trials and non-randomized controlled studies evaluating ceftolozane-tazobactam and its comparators in adult patients with GNB infections were included.

RESULTS

A total of 13 studies were included. Overall, patients receiving ceftolozane-tazobactam had significant advantages in clinical cure (odds ratio [OR], 1.62; 95% CI, 1.05-2.51) and microbiological eradication (OR, 1.43; 95% CI, 1.19-1.71), especially in Pseudomonas aeruginosa-infected patients. Ceftolozane-tazobactam had a significant advantage in clinical success or microbial eradication compared with polymyxin/aminoglycosides (PL/AG) or levofloxacin. There were no significant differences in adverse events (AEs), Clostridium difficile infection (CDI), and mortality between ceftolozane-tazobactam and comparators. Notably, ceftolozane-tazobactam showed a significantly lower risk of acute kidney injury compared with PL/AG.

CONCLUSIONS

Ceftolozane-tazobactam showed excellent clinical and microbiological efficacy in treating GNB, especially P. aeruginosa-induced infections. The overall safety profile of ceftolozane-tazobactam was comparable to other antimicrobials, with no increased risk of CDI and obvious advantage over antibacterial agents with high nephrotoxicity.

Treatment of severe multi-drug resistant Pseudomonas aeruginosa infections

Pseudomonas aeruginosa is the microorganism most frequently involved in the main ICU-acquired infections, with special importance in ventilator associated pneumonia. Its importance lies, in addition to its high incidence in critically ill patients, in the severity of the infections it causes and in the difficulty of its antimicrobial treatment, directly related to the high percentage of resistance to antibiotics classically considered first-line. New active antibiotics have recently been developed against Pseudomonas aeruginosa, even against multi-drug resistant strains. This review analyzes both the differential characteristics of Pseudomonas aeruginosa infections and the new therapeutic options, focusing on multi-drug resistant Pseudomonas aeruginosa.

Efficacy of Combination Therapies for the Treatment of Multi-Drug Resistant Gram-Negative Bacterial Infections Based on Meta-Analyses

There is increasing evidence regarding the optimal therapeutic strategies for multidrug-resistant (MDR) bacteria that cause common infections and are resistant to existing antibiotics. Combination therapies, such as β-lactam combined with β-lactamase inhibitors or combination antibiotics, is a therapeutic strategy to overcome MDR bacteria. In recent years, the therapeutic options have expanded as certain combination drugs have been approved in more countries. However, only a handful of guidelines support these options, and the recommendations are based on low-quality evidence. This review describes the significance and efficacy of combination therapy as a therapeutic strategy against Gram-negative MDR pathogens based on previously reported meta-analyses.

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.

Ceftolozane/tazobactam for difficult-to-treat Gram-negative infections: A real-world tertiary hospital experience

OBJECTIVE

To evaluate the real-world clinical efficacy of ceftolozane/tazobactam (C/T) in difficult-to-treat infections caused by multi-drug resistant Gram-negative microorganisms, including carbapenem-resistant Pseudomonas aeruginosa.

METHODS

Retrospective cohort study of adult patients treated with C/T for at least 48 hours for infections caused by multi-drug resistant Gram-negative bacteria in a tertiary hospital from May 2016 until August 2019. The primary outcome analysed was clinical failure, defined as a composite of symptomatology persistence after 7 days of C/T treatment, infection recurrence, and/or all-cause mortality within 30 days of follow-up.

RESULTS AND DISCUSSION

96 episodes of C/T treatment were included, mostly consisting of targeted treatments (83.9%) for the following sources of infection: intra-abdominal (22.6%), urinary tract (25.8%), skin and soft tissue (19.4%), hospital-acquired pneumonia (14%), and other (6.4%). The most frequently isolated bacteria were carbapenem-resistant (88, 94.6%). Clinical failure rate was 30.1%, due to persistent infection at day 7 (4.3%), recurrence of the initial infection (16.1%), or 30-day all-cause mortality (8.6%). Adverse events most frequently reported were Clostridium difficile infection (9%) and cholestasis (8%).

WHAT IS NEW AND CONCLUSION

C/T showed a favourable clinical profile for difficult-to-treat multidrug-resistant and carbapenem-resistant Gram-negative infections, regardless of the source of infection.

New evidence for managing Gram-negative bloodstream infections

PURPOSE OF REVIEW

Gram-negative bloodstream infections (GNBSI) are common and carry considerable mortality. Treatment is complicated by increasing antimicrobial resistance, posing a challenge for timely appropriate antibiotics and limiting the choices of effective definitive therapy. The present review aims to summarize recent studies addressing the management of GNBSI.

RECENT FINDINGS

New rapid diagnostic tests (RDT) for pathogen identification and antibiotic susceptibility are associated with improved antimicrobial stewardship and reduced length of stay. No mortality benefit or patient-related outcomes are reported. Data regarding the use of new beta-lactam beta-lactamase inhibitors (BLBLIs) for treating multidrug resistance Gram-negative bacteria is supportive, though questions regarding combinations, optimal dosing, mode of administration, and resistance emergence remain to be clarified. Current data regarding cefiderocol necessitates further studies in order to support its use in GNBSI. Shortened (≤7 days) duration of therapy and early oral step down for GNBSI are supported by the literature. The role of repeated blood cultures should be further defined.

SUMMARY

RDTs should be implemented to improve antibiotic stewardship. Clinical implications on patient-related outcomes should be evaluated. New BLBLIs show promise in the treatment of GNBSI. Additional data are needed regarding the use of cefiderocol. Antibiotic therapy should be shortened and early oral step down should be considered.

Blood Stream Infections from MDR Bacteria

BACKGROUND

Bloodstream infections (BSIs) constitute a growing public health concern, are among the most severe nosocomial pathologies, and are considered a worldwide cause of unfaithful outcomes, increasing treatment costs and diagnostic uncertainties. BSIs are one of the most frequent lethal conditions that are managed in intensive care units (ICUs). In the case of septic shock, immune deficiency, and delayed treatment, even with adequate antimicrobial therapy and/or source control, the outcomes are often unfavorable.

METHODS

this review article summarizes the epidemiological and microbiological characteristics of BSIs with a particular focus on ICU acquired BSIs (ICU-BSIs), which are usually caused by multidrug-resistant (MDR) pathogens. For this reason, their antimicrobial resistance patterns and therapeutic options have also been compiled.

RESULTS

ICU-acquired BSIs prevail in 5-7% of ICU patients. Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosae are the pathogens most often responsible for MDR infections. MDR Enterobacteriaceae have seen their prevalence increase from 6.2% (1997-2000) to 15.8% (2013-2016) in recent years.

CONCLUSIONS

Considering that prevention and treatment of sepsis is nowadays considered a global health priority by the World Health Organization, it is our obligation to invest more resources into solving or reducing the spread of these unfaithful infections. It is relevant to identify patients with risk factors that make them more susceptible to BSIs, to guarantee earlier molecular or microbiological diagnoses, and more rapidly appropriate treatment by using de-escalation strategies where possible.

New Perspectives on Antimicrobial Agents: Ceftolozane-Tazobactam

Ceftolozane-tazobactam (C/T) is a new fifth-generation cephalosporin/beta-lactamase inhibitor combination approved by the Food and Drug Administration and the European Medicines Agency for treatment of complicated intraabdominal infections, complicated urinary tract infections, and hospital-acquired pneumonia in adult patients. This review will briefly describe the pharmacology of C/T and focus on the emerging clinical trial and real-world data supporting its current utilization. Additionally, our synthesis of these data over time has set our current usage of C/T at Barnes-Jewish Hospital (BJH). C/T is primarily employed as directed monotherapy at BJH when Pseudomonas aeruginosa isolates are identified with resistance to other beta-lactams. C/T can also be used empirically in specific clinical situations at BJH prior to microbiological detection of an antibiotic-resistant P. aeruginosa isolate. These situations include critically ill patients in the intensive care unit (ICU) setting, where there is a high likelihood of infection with multidrug-resistant (MDR) P. aeruginosa; patients failing therapy with a carbapenem; specific patient populations known to be at high risk for infection with MDR P. aeruginosa (e.g., lung transplant and cystic fibrosis patients); and patients know to have previous infection or colonization with MDR P. aeruginosa.

Clinical and Microbiologic Efficacy and Safety of Imipenem/Cilastatin/Relebactam in Complicated Infections: A Meta-analysis

BACKGROUND

Antimicrobial resistance is on the rise. The use of redundant and inappropriate antibiotics is contributing to recurrent infections and resistance. Newer antibiotics with more robust coverage for Gram-negative bacteria are in great demand for complicated urinary tract infections (cUTIs), complicated intra-abdominal infections (cIAIs), hospital-acquired bacterial pneumonia (HABP), and ventilator-associated bacterial pneumonia (VABP).

MATERIALS AND METHODS

We performed this meta-analysis to evaluate the efficacy and safety profile of a new antibiotic, Imipenem/cilastatin/relebactam, compared to other broad-spectrum antibiotics for complicated infections. We conducted a systemic review search on PubMed, Embase, and Central Cochrane Registry. We included randomized clinical trials-with the standard of care as comparator arm with Imipenem/cilastatin/relebactam as intervention arm. For continuous variables, the mean difference was used. For discrete variables, we used the odds ratio. For effect sizes, we used a confidence interval of 95%. A P-value of less than 0.05 was used for statistical significance. Analysis was done using a random-effects model irrespective of heterogeneity. Heterogeneity was evaluated using the I² statistic.

RESULTS

The authors observed similar efficacy at clinical and microbiologic response levels on early follow-up and late follow-up compared to the established standard of care. The incidence of drug-related adverse events, serious adverse events, and drug discontinuation due to adverse events were comparable across both groups.

CONCLUSION

Imipenem/cilastatin/relebactam has a non-inferior safety and efficacy profile compared to peer antibiotics to treat severe bacterial infections (cUTIs, cIAIs, HABP, VABP).