Combination of Vancomycin or Daptomycin and Beta-lactam Antibiotics: A Meta-analysis

Comparison of efficacy and safety between daptomycin plus β-lactam and daptomycin monotherapy for bloodstream infections due to gram-positive cocci: A systematic review and meta-analysis

Objectives

We performed a comprehensive systematic review and meta-analysis to evaluate the clinical or microbiological outcomes and safety of a combination of daptomycin (DAP) and β-lactams compared to DAP monotherapy in patients with blood stream infection (BSI) due to gram-positive cocci (GPC).

Methods

We searched Scopus, PubMed, EMBASE, CINAHL, and Ityuushi databases up to January 30, 2023. Outcomes included all-cause mortality, clinical failure, and creatine phosphokinase (CPK) elevation.

Results

Six cohorts or case-control studies fulfilled the inclusion criteria and were included in the final meta-analysis. Combination therapy of DAP and β-lactams significantly reduced the mortality and clinical failure rate for all BSI due to GPC compared with the DAP monotherapy (mortality, odds ratio [OR] = 0.63, 95 % confidence interval [CI] = 0.41-0.98; clinical failure, OR = 0.42, 95 % CI = 0.22-0.81). In contrast, no significant difference was noted in the incidence of CPK elevation between the two groups (OR = 0.85, 95 % CI = 0.39-1.84).

Conclusion

Altogether, combination therapy of DAP and β-lactams can improve the prognosis for patients with BSI due to GPC compared with DAP alone. Therefore, it should be considered as an option for the empirical treatment of BSI caused by GPC.

Clinical characteristics and antibiotic resistance profile of invasive MRSA infections in newborn inpatients: a retrospective multicenter study from China

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) can cause invasive infections with significant mortality in neonates. This study aimed to analyze the clinical characteristics and antibiotic resistance profiles of invasive MRSA infections and determine risk factors associated with invasive MRSA infections in newborn inpatients.

METHODS

This multicenter retrospective study of inpatients from eleven hospitals in the Infectious Diseases Surveillance of Pediatrics (ISPED) group of China was performed over a two-year period (2018-2019). Statistical significance was calculated by applying the χ2 test or by Fisher's exact test in the case of small sample sizes.

RESULTS

A total 220 patients were included. Among included cases, 67 (30.45%) were invasive MRSA infections, including two deaths (2.99%), while 153 (69.55%) were noninvasive infections. The invasive infections of MRSA occurred at a median age of 8 days on admission, which was significantly younger compared to 19 days in noninvasive cases. Sepsis (86.6%) was the most common invasive infection, followed by pneumonia (7.4%), bone and joint infections (3.0%), central nervous system infection (1.5%), and peritonitis (1.5%). Congenital heart disease, low birth weight infant (<2500 g), but not preterm neonates, and bronchopulmonary dysplasia, were more commonly found in invasive MRSA infections. All these isolates were susceptible to vancomycin and linezolid and were resistant to penicillin. Additionally, 69.37% were resistant to erythromycin, 57.66% to clindamycin, 7.04% to levofloxacin, 4.62% to sulfamethoxazole-trimethoprim, 4.29% to minocycline, 1.33% to gentamicin, and 3.13% were intermediate to rifampin.

CONCLUSION

Low age at admission (≤8 days), congenital heart disease, and low birth weight were associated with invasive MRSA infections in neonates, and no isolates resistant to vancomycin and linezolid were found. Determining these risks in suspected neonates may help identify patients with imminent invasive infections who may require intensive monitoring and therapy.

Growth Arrest of Staphylococcus aureus Induces Daptomycin Tolerance via Cell Wall Remodelling

Almost all bactericidal drugs require bacterial replication and/or metabolic activity for their killing activity. When these processes are inhibited by bacteriostatic antibiotics, bacterial killing is significantly reduced. One notable exception is the lipopeptide antibiotic daptomycin, which has been reported to efficiently kill growth-arrested bacteria. However, these studies employed only short periods of growth arrest (<1 h), which may not fully represent the duration of growth arrest that can occur in vivo. We found that a growth inhibitory concentration of the protein synthesis inhibitor tetracycline led to a time-dependent induction of daptomycin tolerance in S. aureus, with an approximately 100,000-fold increase in survival after 16 h of growth arrest, relative to exponential-phase bacteria. Daptomycin tolerance required glucose and was associated with increased production of the cell wall polymers peptidoglycan and wall-teichoic acids. However, while the accumulation of peptidoglycan was required for daptomycin tolerance, only a low abundance of wall teichoic acid was necessary. Therefore, whereas tolerance to most antibiotics occurs passively due to a lack of metabolic activity and/or replication, daptomycin tolerance arises via active cell wall remodelling. IMPORTANCE Understanding why antibiotics sometimes fail to cure infections is fundamental to improving treatment outcomes. This is a major challenge when it comes to Staphylococcus aureus because this pathogen causes several different chronic or recurrent infections. Previous work has shown that a lack of replication, as often occurs during infection, makes bacteria tolerant of most bactericidal antibiotics. However, one antibiotic that has been reported to kill nonreplicating bacteria is daptomycin. In this work, we show that the growth arrest of S. aureus does in fact lead to daptomycin tolerance, but it requires time, nutrients, and biosynthetic pathways, making it distinct from other types of antibiotic tolerance that occur in nonreplicating bacteria.

Escalation of antimicrobial resistance among MRSA part 2: focus on infections and treatment

INTRODUCTION

MRSA is associated with causing a variety of infections including skin and skin structure infections, catheter and device-related (e.g. central venous catheter, prosthetic heart valve) infections, infectious endocarditis, blood stream infections, bone, and joint infections (e.g. osteomyelitis, prosthetic joint, surgical site), central nervous system infections (e.g. meningitis, brain/spinal cord abscess, ventriculitis, hydrocephalus), respiratory tract infections (e.g. hospital-acquired pneumonia, ventilator-associated pneumonia), urinary tract infections, and gastrointestinal infections. The emergence and spread of multidrug resistant (MDR) MRSA clones has limited therapeutic options. Older agents such as vancomycin, linezolid and daptomycin and a variety of newer MRSA antimicrobials and combination therapy are available to treat serious MRSA infections.

AREAS COVERED

The authors discuss infections caused by MRSA as well as common older and newer antimicrobials and combination therapy for MRSA infections. A literature search of MRSA was performed via PubMed (up to September 2022), using the keywords: antimicrobial resistance; β-lactams; multidrug resistance, Staphylococcus aureus, vancomycin; glycolipopeptides.

EXPERT OPINION

Innovation, discovery, and development of new and novel classes of antimicrobial agents are critical to expand effective therapeutic options. The authors encourage the judicious use of antimicrobials in accordance with antimicrobial stewardship programs along with infection-control measures to minimize the spread of MRSA.

Daptomycin synergistic properties from in vitro and in vivo studies: a systematic review

INTRODUCTION

Daptomycin is a bactericidal lipopeptide antibiotic approved for the treatment of systemic infections (i.e. skin and soft tissue infections, bloodstream infections, infective endocarditis) caused by Gram-positive cocci. It is often prescribed in association with a partner drug to increase its bactericidal effect and to prevent the emergence of resistant strains during treatment; however, its synergistic properties are still under evaluation.

METHODS

We performed a systematic review to offer clinicians an updated overview of daptomycin synergistic properties from in vitro and in vivo studies. Moreover, we reported all in vitro and in vivo data evaluating daptomycin in combination with other antibiotic agents, subdivided by antibiotic classes, and a summary graph presenting the most favourable combinations at a glance.

RESULTS

A total of 92 studies and 1087 isolates (723 Staphylococcus aureus, 68 Staphylococcus epidermidis, 179 Enterococcus faecium, 105 Enterococcus faecalis, 12 Enterococcus durans) were included. Synergism accounted for 30.9% of total interactions, while indifferent effect was the most frequently observed interaction (41.9%). Antagonistic effect accounted for 0.7% of total interactions. The highest synergistic rates against S. aureus were observed with daptomycin in combination with fosfomycin (55.6%). For S. epidermidis and Enterococcus spp., the most effective combinations were daptomycin plus ceftobiprole (50%) and daptomycin plus fosfomycin (63.6%) or rifampicin (62.8%), respectively.

FUTURE PERSPECTIVES

We believe this systematic review could be useful for the future updates of guidelines on systemic infections where daptomycin plays a key role.

Comparing the Outcomes of Ceftaroline plus Vancomycin or Daptomycin Combination Therapy versus Vancomycin or Daptomycin Monotherapy in Adults with Methicillin-Resistant Staphylococcus aureus Bacteremia—A Meta-Analysis

Introduction: Combination therapy with daptomycin plus ceftaroline to treat methicillin-resistant Staphylococcus aureus bacteremia has been reported to reduce methicillin-resistant Staphylococcus aureus bacteremia-related mortality. The purpose of the current meta-analysis was to compare the clinical outcome of methicillin-resistant Staphylococcus aureus bacteremia in patients treated with daptomycin or vancomycin plus ceftaroline combination therapy versus daptomycin or vancomycin monotherapy. Methods: Studies were included if they directly compared the efficacy of daptomycin or vancomycin plus ceftaroline combination therapy with that of daptomycin or vancomycin monotherapy in the treatment of methicillin-resistant Staphylococcus aureus bacteremia in adult patients. Results: One randomized controlled trial and five retrospective studies were included in the meta-analysis. The combination therapy group had an in-hospital mortality, duration of bacteremia, and adverse event rate similar to those patients who had monotherapy. There was less bacteremia recurrence in the combination group. Initial combination therapy with ceftaroline for the treatment of methicillin-resistant Staphylococcus aureus bacteremia showed a trend of reducing the risk of in-hospital mortality in the current meta-analysis. Conclusions: Randomized controlled trials are needed to further study the role of initial combination therapy with daptomycin or vancomycin plus ceftaroline in the treatment of methicillin-resistant Staphylococcus aureus bacteremia.

The Impact of Implementing the Virtuo Blood Culture System on the Characteristics and Management of Patients with Staphylococcus aureus Bacteremia

Persistent Staphylococcus aureus bacteremia (SAB) has been associated with increased mortality. Enhanced microbial detection with new blood culture technology may improve detection of S. aureus in patients with SAB. We performed a 24-month retrospective study of hospitalized adults with SAB and an infectious diseases consult comparing two time periods pre- (January to December 2018) and postimplementation (January to December 2019) in which the VersaTREK and BacT/Alert Virtuo blood culture systems were used, respectively. Measurements included SAB duration, time to positivity, source of bacteremia, antimicrobial therapy, and mortality. A total of 416 episodes of SAB occurred during the study period: 176 (42%) pre- and 240 (58%) postimplementation. Patients in both periods had similar clinical characteristics; however, patients in the postimplementation period were more likely to have intermediate (3 to 6 days; 23% versus 40%; P < 0.001) and prolonged SAB duration (>7 days; 4% versus 14%; P < 0.001). Combination antistaphylococcal therapy was more frequent postimplementation (6.3% pre- versus 15.8% postimplementation; P = 0.003), and the median time to source control was shorter (4 versus 2 days; P = 0.02). Median time to positivity for the index blood culture was shorter postimplementation (17.8 h pre- versus 13.3 h postimplementation; P < 0.001). There was no difference in 90-day all-cause readmissions (51% versus 44%; P = 0.11) or mortality (32% versus 32%; P = 0.95). An increased frequency of prolonged SAB with increased use of combination antistaphylococcal therapy was noted with implementation of a new blood culture system, likely secondary to the blood culture media; however, no differences on adverse outcomes were noted.

Beta Lactams Plus Daptomycin Combination Therapy for Infective Endocarditis: An Italian National Survey (BADAS)

BACKGROUND

infective endocarditis (IE) remains a severe disease frequently encountered in clinical practice and often requiring interdisciplinary medical and surgical management. This national survey aims to describe the clinical prescribing habits of the use of daptomycin in the setting of IE and the possible role for combination therapy with beta-lactams.

METHODS

The study was a cross-sectional internet-based questionnaire survey on therapy with daptomycin. The questionnaire was designed with closed-ended questions and distributed using the SurveyMonkey^® platform between October 2019 to December 2020.

RESULTS

55 clinicians from twelve Italians regions joined the questionnaire. The survey reported use of daptomycin as first-line choice in 31.48% of cases and as the first-line anti-MRSA agent in 44.44%. The empiric use of daptomycin was stated in the high suspicion of MRSA rather than MSSA, enterococcal or streptococcal IE. The rationale of daptomycin for the empirical treatment of native and prosthetic valve IE was mostly the possibility of administering an aminoglycoside-sparing combination regimen, high bacterial killing rate and high clinical efficacy.

CONCLUSIONS

In conclusion, in selected patients, daptomycin could be a feasible option for the treatment of infective endocarditis in line with data from the European registry of daptomycin.

Impact of PrsA on membrane lipid composition during daptomycin-resistance-mediated β-lactam sensitization in clinical MRSA strains

BACKGROUND

The cyclic anionic lipopeptide daptomycin is used in the treatment of severe infections caused by Gram-positive pathogens, including MRSA. Daptomycin resistance, although rare, often results in treatment failure. Paradoxically, in MRSA, daptomycin resistance is usually accompanied by a concomitant decrease in β-lactam resistance in what is known as the 'see-saw effect'. This resensitization is extensively used for the treatment of MRSA infections, by combining daptomycin and a β-lactam antibiotic, such as oxacillin.

OBJECTIVES

We aimed: (i) to investigate the combined effects of daptomycin and oxacillin on the lipid composition of the cellular membrane of both daptomycin-resistant and -susceptible MRSA strains; and (ii) to assess the involvement of the post-translocational protein PrsA, which plays an important role in oxacillin resistance in MRSA, in membrane lipid composition and remodelling during daptomycin resistance/β-lactam sensitization.

RESULTS

The combination of microbiological and biochemical studies, with fluorescence microscopy using lipid probes, showed that the lipid composition and surface charge of the daptomycin-resistant cells exposed to daptomycin/oxacillin were dependent on antibiotic concentration and directly associated with PrsA, which influenced cardiolipin remodelling/relocation.

CONCLUSIONS

Our findings show that PrsA, in addition to its post-transcriptional role in the maturation of PBP 2a, is a key mediator of cell membrane remodelling connected to the see-saw effect and may have a key role in the resensitization of daptomycin-resistant strains to β-lactams, such as oxacillin.

The Effect of Combination Therapy on Mortality and Adverse Events in Patients with Staphylococcus aureus Bacteraemia: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Introduction

The findings of randomized controlled trials (RCTs), observational studies, and meta-analyses vary regarding the effectiveness and safety of combination therapy for patients with Staphylococcus aureus bacteraemia (SAB). We aimed to identify the effectiveness and safety of combination therapy in patients with SAB compared with those of monotherapy.

Methods

We performed a systematic review and meta-analysis to compare combination therapy versus monotherapy in patients with SAB. Two authors independently searched PubMed, Embase, and the Cochrane Library of clinical trials until 17 February 2021. Any RCT comparing mortality or adverse events (AEs) of combination therapy versus monotherapy for patients with SAB was eligible. Summary risk ratios (RRs) and 95% confidence intervals (CIs) were evaluated using a random-effects model. The primary outcome was all-cause mortality at any time point. This meta-analysis is registered with the PROSPERO database (CRD42020188176) and reported according to PRISMA guidelines.

Results

In total, 1906 articles were identified and screened, and 14 studies (2367 patients) were included in the meta-analysis. There was no significant difference in the risk of all-cause mortality between the two groups (RR = 1.00; 95% CI 0.83–1.20; P = 0.99; I² = 0%). Similar results were obtained by subgroup analysis of mortality recording time, endocarditis, pathogen resistance, article publication time, number of patients, and adjuvant antibiotics. Notably, combination treatment might significantly increase the risk of drug-related AEs (RR = 1.68; 95% CI 1.06–2.66; P = 0.03; I² = 67%) and nephrotoxicity (RR = 2.30; 95% CI 1.68–3.16; P < 0.00001; I² = 0%), although the occurrences of AEs leading to treatment discontinuation and serious AEs were not significantly different between the two groups.

Conclusions

The meta-analysis suggested that combination therapy could not reduce mortality but might increase the risk of drug-related AEs and nephrotoxicity and should be applied very cautiously. Future studies on combined drug therapy for SAB need careful and rigorous design for specific antibiotic combinations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00539-y.

Select controversies in the management of methicillin-resistant Staphylococcus aureus bacteremia: answers and remaining questions from recent evidence

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia continues to cause significant morbidity and mortality despite advances in medical therapy. Vancomycin therapy remains the standard of care for most cases of MRSA bacteremia but has pharmacokinetic and pharmacodynamic limitations, dosing complications, and known toxicity. Welcomed clinical trials have recently addressed some of the controversies that plague this field, including optimization of vancomycin dosing and use of combination therapy. In this review, we discuss these trials and their implications for clinical care and future research.

Platelet membrane-camouflaged silver metal-organic framework drug system against infections caused by methicillin-resistant Staphylococcus aureus

Background

Due to the intelligent survival strategy and self-preservation of methicillin-resistant Staphylococcus aureus (MRSA), many antibiotics are ineffective in treating MRSA infections. Nano-drug delivery systems have emerged as a new method to overcome this barrier. The aim of this study was to construct a novel nano-drug delivery system for the treatment of MRSA infection, and to evaluate the therapeutic effect and biotoxicity of this system. We prepared a nano silver metal-organic framework using 2-methylimidazole as ligand and silver nitrate as ion provider. Vancomycin (Vanc) was loaded with Ag-MOF, and nano-sized platelet vesicles were prepared to encapsulate Ag-MOF-Vanc, thus forming the novel platelet membrane-camouflaged nanoparticles PLT@Ag-MOF-Vanc.

Results

The synthesized Ag-MOF particles had uniform size and shape of radiating corona. The mean nanoparticle size and zeta potential of PLT@Ag-MOF-Vanc were 148 nm and − 25.6 mV, respectively. The encapsulation efficiency (EE) and loading efficiency (LE) of vancomycin were 81.0 and 64.7 %, respectively. PLT@Ag-MOF-Vanc was shown to be a pH-responsive nano-drug delivery system with good biocompatibility. Ag-MOF had a good inhibitory effect on the growth of three common clinical strains (Escherichia coli, Pseudomonas aeruginosa, and S. aureus). PLT@Ag-MOF-Vanc showed better antibacterial activity against common clinical strains in vitro than free vancomycin. PLT@Ag-MOF-Vanc killed MRSA through multiple approaches, including interfering with the metabolism of bacteria, catalyzing reactive oxygen species production, destroying the integrity of cell membrane, and inhibiting biofilm formation. Due to the encapsulation of the platelet membrane, PLT@Ag-MOF-Vanc can bind to the surface of the MRSA bacteria and the sites of MRSA infection. PLT@Ag-MOF-Vanc had a good anti-infective effect in mouse MRSA pneumonia model, which was significantly superior to free vancomycin, and has no obvious toxicity.

Conclusions

PLT@Ag-MOF-Vanc is a novel effective targeted drug delivery system, which is expected to be used safely in anti-infective therapy of MRSA.

Graphic abstract

Standardized Treatment and Assessment Pathway Improves Mortality in Adults With Methicillin-resistant Staphylococcus aureus Bacteremia: STAPH Study

Background

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) management remains challenging for clinicians. Numerous in vitro studies report synergy when vancomycin (VAN) and daptomycin (DAP) are combined with beta-lactams (BLs), which has led to clinical implementation of these combinations. While shorter durations of bacteremia have often been reported, there has been no significant impact on mortality.

Methods

The Detroit Medical Center (DMC) developed and implemented a clinical pathway algorithm for MRSA BSI treatment in 2016 that included the early use of BL combination therapy with standard of care (VAN or DAP) and a mandatory Infectious Diseases consultation. This was a retrospective, quasi-experimental study at the DMC between 2013 and 2020. Multivariable logistic regression was used to assess the independent association between pathway implementation and 30-day mortality while adjusting for confounding variables.

Results

Overall, 813 adult patients treated for MRSA BSI were evaluated. Compared with prepathway (PRE) patients (n = 379), those treated postpathway (POST; n = 434) had a significant reduction in 30-day and 90-day mortality: 9.7% in POST vs 15.6% in PRE (P = .011) and 12.2% in POST vs 19.0% in PRE (P = .007), respectively.

The incidence of acute kidney injury (AKI) was higher in the PRE compared with the POST group: 9.6% vs 7.2% (P = .282), respectively. After adjusting for confounding variables including Infectious Diseases consult, POST was independently associated with a reduction in 30-day mortality (adjusted odds ratio [aOR], 0.608; 95% CI, 0.375–0.986).

Conclusions

Implementation of an MRSA BSI treatment pathway with early use of BL reduced mortality with no increased rate of AKI. Further prospective evaluation of this pathway approach is warranted.

Current Paradigms of Combination therapy in Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia: Does it Work, Which Combination and For Which Patients?

The last several years have seen an emergence of literature documenting the utility of combination antimicrobial therapy, particularly in the salvage of refractory MRSA bacteremia. Recent clinical data are shaping conundrums of which regimens may be more beneficial, which can be potentially harmful, and which subset of patients stand to benefit from more aggressive treatment regimens than called for by current standards. In addition, the incorporation of combination therapy for MRSA bacteremia should be accompanied by the reminder that antimicrobial therapy does not need to be uniform for the entire duration, with an early intensive phase in high inoculum infections (e.g. with combination therapy), followed by a consolidation phase (i.e. monotherapy). This review and perspective consolidates the recent data on this subject and directs future goals in filling the knowledge gaps to methodically move forward towards improving patient outcomes.

What do beta-lactams add to vancomycin or daptomycin in the treatment of patients with methicillin-resistant Staphylococcus aureus bacteraemia? A review

Several studies have documented the synergy between vancomycin/daptomycin and various beta-lactams, and clinical studies have studied this combination therapy in humans. We review the published literature on this topic to know the utility of the combined treatment with beta-lactams in treating bacteraemia methicillin-resistant Staphylococcus aureus (MRSA) infections. Fifteen observational studies, three randomised clinical trials and three systematics reviews are analysed in this article. Observational studies used ceftaroline, cefazolin, piperacillin/tazobactam or cefepime among the beta-lactams. Clinical trials used cloxacillin or flucloxacillin as the most used beta-lactam in two trials and ceftaroline in one. Three systematic reviews are published. One of them only includes studies with vancomycin and included six studies. The other two systematic reviews include patients with daptomycin or vancomycin and included 15 and 9 studies, respectively. Adding a beta-lactam to vancomycin or daptomycin may help shorten bacteraemia and avoid recurrences in patients with MRSA bacteraemia. There is no evidence that combined therapy improves mortality. Nephrotoxicity in clinical trials precludes the use of combination therapy mainly with cloxacillin or flucloxacillin, but systematic reviews have not found a significant difference in this point in observational studies with other beta-lactams. The role of other beta-lactams such as ceftaroline should be thoroughly studied in these patients.

Adjuvant β-Lactam Therapy Combined with Vancomycin or Daptomycin for Methicillin-Resistant Staphylococcus aureus Bacteremia: a Systematic Review and Meta-analysis

Infections due to methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) seriously threaten public health due to poor outcomes and high mortality. The objective of this study is to perform a systematic review and meta-analysis of the current evidence on adjuvant β-lactam (BL) therapy combined with vancomycin (VAN) or daptomycin (DAP) for MRSAB. PubMed, Embase, and Cochrane Library were systematically searched for publications reporting clinical outcomes of BLs+VAN or BLs+DAP for adult patients with MRSAB through 5 April 2020. Meta-analysis techniques were applied using random effects modeling. Three randomized controlled trials and 12 retrospective cohort studies were identified, totaling 2,594 patients. Combination treatment significantly reduced the risk of clinical failure (risk ratio [RR] = 0.80; 95% confidence interval [CI], 0.66 to 0.96; P = 0.02; I² = 39%), bacteremia recurrence (RR = 0.66; 95% CI, 0.50 to 0.86; P = 0.002; I² = 0%), and persistent bacteremia (RR = 0.65; 95% CI, 0.55 to 0.76; P < 0.00001; I² = 0%) and shortened the duration of bacteremia (standardized mean difference [SMD] = -0.37; 95% CI, -0.48 to -0.25; P < 0.00001; I² = 0%). There was no significant difference in the risk of crude mortality, nephrotoxicity, or thrombocytopenia between groups. Notably, combination treatment might nonsignificantly increase the risk of Clostridium difficile infection (CDI) (RR = 2.13; 95% CI, 0.98 to 4.63; P = 0.06; I² = 0%). Subgroup analysis suggested that DAP+BLs could reduce crude mortality (RR = 0.53; 95% CI, 0.28 to 0.98; P = 0.04; I² = 0%). The meta-analysis suggested that although combination therapy with BLs could improve some microbial outcomes, it could not reduce crude mortality but might increase the risk of CDI and should be applied very cautiously. Regarding mortality reduction, the combination of DAP+cephalosporins appears more promising.