Ceftazidime/Avibactam and Ceftolozane/Tazobactam for Multidrug-Resistant Gram Negatives in Patients with Hematological Malignancies: Current Experiences

Whole genome sequencing analysis of seven unknown resistance mechanisms of carbapenem-resistant Klebsiella pneumoniae strains resistance to ceftazidime-avibactam

AIMS

To investigate alternative resistance mechanisms among seven ceftazidime-avibactam (CZA)-resistant carbapenem-resistant Klebsiella pneumoniae (CRKP) strains lacking common antimicrobial resistance genes (ARGs) using whole genome sequencing.

METHODS AND RESULTS

ARG and virulence factors (VFs) were screened using the ARG database CARD and the VF database, respectively, and identified using genomic annotation data with BLAST+. Six strains were ST11 sequence types (STs), and one was ST2123. ST11 strains harbored more ARGs than the ST2123 strains. All seven strains carried multiple ARGs with efflux-mediated antibiotic resistance, including oqxA, oqxB, tet (A), qacEdltal, CRP, H-NS, Kpn-E, F, G, H, acrA, LptD, acrB, acrD, cpxA, mdtB, and mdtC. These efflux-mediated ARGs were identified in most strains and even all strains. Whole genome sequencing revealed that the ST11 strain carried multiple potential prophages, genomic islands, and integrative and conjugative elements, while the ST2123 strain carried an independent potential prophages and a genomic island.

CONCLUSIONS

Whole genome sequencing analysis revealed that these seven CZA-resistant CRKP strains lacking common ARGs exhibited efflux-mediated antibiotic resistance-associated ARGs. The main mechanism by which CRKP resists CZA is antibiotic inactivation. Except for tet (A), no ARGs and validation experiments related to efflux were found. This study's results provide a new possibility for the resistance mechanism of CRKP to CZA, and we will verify this conclusion through experiments in the future.

Mobilization of the blaKPC-14 gene among heterogenous plasmids in extensively drug-resistant hypervirulent Klebsiella pneumoniae

Introduction

Ceftazidime/avibactam (CZA) is an effective alternative for the treatment of infections caused by KPC-producing carbapenem-resistant Klebsiella pneumoniae (CRKP). However, KPC variants with CZA resistance have been observed in clinical isolates, further limiting the treatment options of clinical use.

Methods

In this study, we isolated three KPC-14-producing CRKP from two patients in intensive care units without CZA therapy. The antimicrobial susceptibility was determined using the broth microdilution method. Three CRKP were subjected to whole-genome sequencing to analyze the phylogenetic relatedness and the carriage of antimicrobial resistance genes and virulence factors. Long-read sequencing was also performed to obtain the complete sequences of the plasmids. The horizontal transfer of the blaKPC-14 gene was evaluated by conjugation experiments.

Results

Three CRKP displayed resistance or reduced susceptibility to ceftazidime/avibactam, colistin, and tigecycline. Single-nucleotide polymorphism (SNP) analysis demonstrated the close phylogenetic distance between these strains. A highly similar IncFII/IncR plasmid encoding blaKPC-14 was shared by three CRKP, with blaKPC-14 located in an NTEKPC-Ib element with the core region of ISKpn27- blaKPC-14-ISKpn6. This structure containing blaKPC-14 was also observed in another tet(A)-carrying plasmid that belonged to an unknown Inc-type in two out of three isolates. The horizontal transferability of these integrated plasmids to Escherichia coli EC600 was confirmed by the cotransmission of tet(A) and blaKPC-14 genes, but the single transfer of blaKPC-14 on the IncFII/IncR plasmid failed. Three CRKP expressed yersiniabactin and carried a hypervirulence plasmid encoding rmpA2 and aerobactin-related genes, and were thus classified as carbapenem-resistant hypervirulent K. pneumoniae (hvKP).

Discussion

In this study, we reported the evolution of a mosaic plasmid encoding the blaKPC-14 gene via mobile elements in extensively drug-resistant hvKP. The blaKPC-14 gene is prone to integrate into other conjugative plasmids via the NTEKPC-Ib element, further facilitating the spread of ceftazidime/avibactam resistance.

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.

Benefits and Safety of Empiric Antibiotic Treatment Active Against KPC-K. pneumoniae in Febrile Neutropenic Patients with Acute Leukemia Who are Colonized with KPC-K. pneumoniae. A 7-Years Retrospective Observational Cohort Study

Purpose

To evaluate the benefits and safety of the empiric antibiotic treatment (EAT) active against KPC-K. pneumoniae in febrile neutropenic patients with acute leukaemia (AL) who are colonised by KPC-K. pneumoniae.

Patients and Methods

A 7-year (2013-2019) retrospective observational cohort study was conducted at the Haematology, Sapienza Rome University (Italy) on 94 febrile neutropenia episodes (FNE) in AL patients KPC-K. pneumoniae carriers treated with active EAT.

Results

Eighty-two (87%) FNE were empirically treated with antibiotic combinations [38 colistin-based and 44 ceftazidime-avibactam (CAZAVI)-based], 12 with CAZAVI monotherapy. Successful outcomes were observed in 88/94 (94%) FNE, 46/49 (94%) microbiologically documented infections, and 24/27 (89%) gram-negative bloodstream infections (GNB-BSI). Mortality due to infective causes was 4.2% (2.1% within 1 week). KPC-K. pneumoniae infections caused 28/94 FNE (30%) and KPC-K. pneumoniae-BSI was documented in 22 FNE (23.4%) (85% of GNB-BSI), in all cases patients received active EAT, and 21 survived. KPC-K.pneumoniae-BSI mortality rate was 4.5%. CAZAVI-based EAT showed better results than colistin-based EAT (55/56 vs 33/38, p = 0.037), overall and without EAT modification (41/56 vs 20/38, p = 0.02). Empirical combinations including CAZAVI were successful in 98% of cases (43/44 vs 33/38 for colistin-based EAT, p = 0.01), without modifications in 82% (36/44 vs 20/28, p = 0.02). All deaths occurred in patients treated with colistin-based EAT (4/38 vs 0/56, p = 0.02). CAZAVI-containing EAT was the only independent factor for an overall successful response (HR 0.058, CI 0.013-1.072, p = 0.058). Nephrotoxicity occurred in 3(8%) patients undergoing colistin-based EAT (none in those undergoing CAZAVI-based EAT, p = 0.02).

Conclusion

KPC-K. pneumoniae infections are frequent in colonised AL patients with FNE. EAT with active antibiotics, mainly CAZAVI-based combinations, was effective, safe, and associated with low overall and KPC-K. pneumoniae-BSI-related mortality.

Bacterial spectrum and antimicrobial resistance pattern in cancer patients with febrile neutropenia

BACKGROUND

Bloodstream infections are serious complications in neutropenic cancer patients. There has been a universal pickup in multidrug resistant (MDR) strains. For individuals who are at high risk for infections caused by MDR bacteria, a novel de-escalation strategy has been developed. Determine the bacterial spectrum and antibiotic resistance pattern in febrile neutropenic cancer patients was the goal of this investigation.

MATERIALS AND METHODS

From 2019 to 2020, 60 cancer patients with febrile neutropenia who were sent to Isfahan's Omid Hospital were included in this retrospective analysis. Experiments were done on the antimicrobial susceptibility of isolated bacterial infections.

RESULTS

The patients' average age was 43.35±15.59 years. Ninety-one percent (55/61) of the 60 patients had hematologic malignancies, and 8.3 percent (5/61) had solid tumors. The majority of the germs were gram-negative bacteria (66.7 percent). E. coli was the pathogen that was isolated the most frequently (26.7%), followed by Klebsiella (16.7 percent). In addition, the most prevalent identified Gram-positive bacteria was Staphylococcus epidermidis (21.7 percent). Third-generation cephalosporin (ESBL-E) resistance was present in 50% of E. coli, along with 50% resistance to cotrimoxazole, ciprofloxacin, and piperacillin, 31% resistance to amikacin, and 20% resistance to meropenem (CRE). They had an 80% sensitivity to amikacin and a 70% sensitivity to ciprofloxacin. Ten percent of our patients had antibiotic resistance in the antibiogram (XDR).

CONCLUSION

In summary, most bacterial infections were resistant to different medications. The emergence and spread of Gram-negative bacteria that are resistant to antibiotics can be stopped by prudent antibiotic use.

Molecular Mechanisms Mediating Ceftazidime/Avibactam Resistance Amongst Carbapenem-Resistant Klebsiella pneumoniae Isolates from Cancer Patients

Background

A growing body of evidence suggests that ceftazidime/avibactam (CZA) is a potential therapeutic option for carbapenem-resistant Klebsiella pneumoniae (CRKP) infections; however, resistant strains are increasingly emerged worldwide. Herein, we deemed to investigate the susceptibility profile of CRKP isolates from cancer patients to CZA and to identify the underlying resistance mechanisms.

Methods

Clinical samples were obtained from adult patients admitted to the Oncology Center of Mansoura University, Mansoura, Egypt. The antibiotic susceptibility pattern of K. pneumoniae isolates to different antibiotics was tested by the modified Kirby Bauer's disc diffusion method. Minimum inhibitory concentrations of CZA were assessed using broth microdilution method. Screening for carbapenemase-producing strains was achieved by the modified Hodge test. Multiplex polymerase chain reactions (PCRs) were conducted for uncovering of carbapenemase-encoding genes (bla_KPC, bla_VIM, bla_IMP, bla_NDM-1 , and bla_OXA-48 ), and outer membrane porin genes (ompK35 and ompK36).

Results

A total of 12 CZA-resistant isolates were identified out of 47 CRKP isolates (25.5%). The MIC₅₀ and MIC₉₀ of CZA against CRKP were 1 and 64 µg/mL, respectively. Risk factors for CZA resistance included chronic kidney disease, mechanical ventilation, longer length of hospital stay, and ICU admission. The multivariate logistic regression demonstrated that longer length of hospital stay (P=0.03) was the only independent predictor for acquisition of CZA-resistant isolates. The leading mechanism for CZA resistance was sustained by bla_KPC (50%), meanwhile 16.7% and 8.3% of the CZA-resistant isolates harbored bla_OXA-48 and bla_OXA-48 /bla_NDM-1 , respectively. The MBL-encoding genes bla_NDM-1 and bla_IMP were detected in 16.7% and 8.3% of the isolates, respectively. Absence of both ompK35 and ompK36 was observed in 58.3% of the CZA-resistant isolates.

Conclusion

CZA has displayed superior in vitro activity against CRKP isolates in comparison to other antibiotics; however, thorough molecular characterization of resistant strains is highly recommended in future studies to detect and monitor the emergence of further tackling strains.

Pseudomonas aeruginosa Bloodstream Infections in Patients with Cancer: Differences between Patients with Hematological Malignancies and Solid Tumors

Objectives: To assess the clinical features and outcomes of Pseudomonas aeruginosa bloodstream infection (PA BSI) in neutropenic patients with hematological malignancies (HM) and with solid tumors (ST), and identify the risk factors for 30-day mortality. Methods: We performed a large multicenter, retrospective cohort study including onco-hematological neutropenic patients with PA BSI conducted across 34 centers in 12 countries (January 2006−May 2018). Episodes occurring in hematologic patients were compared to those developing in patients with ST. Risk factors associated with 30-day mortality were investigated in both groups. Results: Of 1217 episodes of PA BSI, 917 occurred in patients with HM and 300 in patients with ST. Hematological patients had more commonly profound neutropenia (0.1 × 109 cells/mm) (67% vs. 44.6%; p < 0.001), and a high risk Multinational Association for Supportive Care in Cancer (MASCC) index score (32.2% vs. 26.7%; p = 0.05). Catheter-infection (10.7% vs. 4.7%; p = 0.001), mucositis (2.4% vs. 0.7%; p = 0.042), and perianal infection (3.6% vs. 0.3%; p = 0.001) predominated as BSI sources in the hematological patients, whereas pneumonia (22.9% vs. 33.7%; p < 0.001) and other abdominal sites (2.8% vs. 6.3%; p = 0.006) were more common in patients with ST. Hematological patients had more frequent BSI due to multidrug-resistant P. aeruginosa (MDRPA) (23.2% vs. 7.7%; p < 0.001), and were more likely to receive inadequate initial antibiotic therapy (IEAT) (20.1% vs. 12%; p < 0.001). Patients with ST presented more frequently with septic shock (45.8% vs. 30%; p < 0.001), and presented worse outcomes, with increased 7-day (38% vs. 24.2%; p < 0.001) and 30-day (49% vs. 37.3%; p < 0.001) case-fatality rates. Risk factors for 30-day mortality in hematologic patients were high risk MASCC index score, IEAT, pneumonia, infection due to MDRPA, and septic shock. Risk factors for 30-day mortality in patients with ST were high risk MASCC index score, IEAT, persistent BSI, and septic shock. Therapy with granulocyte colony-stimulating factor was associated with survival in both groups. Conclusions: The clinical features and outcomes of PA BSI in neutropenic cancer patients showed some differences depending on the underlying malignancy. Considering these differences and the risk factors for mortality may be useful to optimize their therapeutic management. Among the risk factors associated with overall mortality, IEAT and the administration of granulocyte colony-stimulating factor were the only modifiable variables.

Effect of Combination Antibiotic Empirical Therapy on Mortality in Neutropenic Cancer Patients with Pseudomonas aeruginosa Pneumonia

To assess the effect of combination antibiotic empirical therapy on 30-day case-fatality rate in neutropenic cancer patients with Pseudomonas aeruginosa (PA) bacteremic pneumonia. This was a multinational, retrospective cohort study of neutropenic onco-hematological patients with PA bloodstream infection (BSI) (2006−2018). The effect of appropriate empirical combination therapy, appropriate monotherapy and inappropriate empirical antibiotic therapy [IEAT] on 30-day case-fatality was assessed only in patients with PA bacteremic pneumonia. Among 1017 PA BSI episodes, pneumonia was the source of BSI in 294 (28.9%). Among those, 52 (17.7%) were caused by a multidrug-resistant (MDR) strain and 68 (23.1%) received IEAT, mainly when the infection was caused by an MDR strain [38/52 (73.1%) vs. 30/242 (12.4%); p < 0.001]. The 30-day case-fatality rate was higher in patients with PA bacteremic pneumonia than in those with PA BSI from other sources (55.1% vs. 31.4%; p < 0.001). IEAT was associated with increased 30-day case-fatality (aHR 1.44 [95%CI 1.01−2.03]; p = 0.042), whereas the use of appropriate combination empirical treatment was independently associated with improved survival (aHR 0.46 [95%CI 0.27−0.78]; p = 0.004). Appropriate empirical monotherapy was not associated with improved overall survival (aHR 1.25 [95%CI 0.76−2.05]; p = 0.39). Combination antibiotic empirical therapy should be administered promptly in febrile neutropenic patients with suspected pneumonia as the source of infection.

Therapeutic Strategies for Emerging Multidrug-Resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates are frequent causes of serious nosocomial infections that may compromise the selection of antimicrobial therapy. The goal of this review is to summarize recent epidemiologic, microbiologic, and clinical data pertinent to the therapeutic management of patients with infections caused by MDR/XDR-P. aeruginosa. Historically, conventional antipseudomonal β-lactam antibiotics have been used for the empiric treatment of MDR/XDR-P. aeruginosa. Owing to the remarkable capacity of P. aeruginosa to confer resistance via multiple mechanisms, these traditional therapies are often rendered ineffective. To increase the likelihood of administering empiric antipseudomonal therapy with in vitro activity, a second agent from a different antibiotic class is often administered concomitantly with a traditional antipseudomonal β-lactam. However, combination therapy may pose an increased risk of antibiotic toxicity and secondary infection, notably, Clostridioides difficile. Multiple novel agents that demonstrate in vitro activity against MDR-P. aeruginosa (e.g., β-lactam/β-lactamase inhibitor combinations and cefiderocol) have been recently granted US Food and Drug Administration (FDA) approval and are promising additions to the antipseudomonal armamentarium. Even so, comparative clinical data pertaining to these novel agents is sparse, and concerns surrounding the scarcity of antibiotics active against refractory MDR/XDR-P. aeruginosa necessitates continued assessment of alternative therapies. This is particularly important in patients with cystic fibrosis (CF) who may be chronically colonized and suffer from recurrent infections and disease exacerbations due in part to limited efficacious antipseudomonal agents. Bacteriophages represent a promising candidate for combatting recurrent and refractory infections with their ability to target specific host bacteria and circumvent traditional mechanisms of antibiotic resistance seen in MDR/XDR-P. aeruginosa. Future goals for the management of these infections include increased comparator clinical data of novel agents to determine in what scenario certain agents may be preferred over others. Until then, appropriate treatment of these infections requires a thorough evaluation of patient- and infection-specific factors to guide empiric and definitive therapeutic decisions.

Successful treatment with HLA-matched peripheral hematopoietic stem cell transplantation for very severe hepatitis-associated aplastic anemia complicated with multidrug-resistant bacterial and fungal infections: A case report

Hepatitis-associated aplastic anemia (HAAA) is a life-threatening hematologic disorder characterized by bone marrow failure. Allogeneic hematopoietic stem cell transplantation (HSCT) is the first-line treatment for HAAA. Severe infection and complications in patients with very severe aplastic anemia are the challenges to the efficacy of HSCT. We report a rare case of successful transplantation with HLA-matched peripheral hematopoietic stem cells for a 15-year-old girl suffering from HAAA with multidrug-resistant bacterial and fungal infections. Through effectively controlling infection and optimal timing of transplantation by adjusting the conditioning regimen, the allo-HSCT was successfully performed for the patient. Updated data of following-up 26 months after transplantation showed that the patient was still in complete remission with a good quality of life. This case provided a reference for treating severely infected patients with HAAA before HSCT.

Ceftazidime-Avibactam for the Treatment of Serious Gram-Negative Infections with Limited Treatment Options: A Systematic Literature Review

INTRODUCTION

A systematic literature review was undertaken to evaluate real-world use of ceftazidime-avibactam for infections due to aerobic Gram-negative organisms in adults with limited treatment options.

METHODS

Literature searches retrieved peer-reviewed publications and abstracts from major international infectious disease congresses from January 2015 to February 2021. Results were screened using pre-defined criteria to limit the dataset to relevant publications (notable exclusions were paediatric data and outcomes data for bacteria intrinsically resistant to ceftazidime-avibactam). Data for included publications were subjected to qualitative synthesis.

RESULTS

Seventy-three relevant publications (62 peer-reviewed articles; 10 abstracts) comprising 1926 patients treated with ceftazidime-avibactam (either alone or combined with other antimicrobials) and 1114 comparator/control patients were identified. All patients were hospitalised for serious illness and most had multiple comorbidities. The most common infections were pneumonia, bacteraemia, and skin/soft tissue, urinary tract, or abdominal infections; smaller numbers of patients with meningitis, febrile neutropenia, osteomyelitis, and cystic fibrosis were also included. Carbapenem-resistant or carbapenemase-producing Enterobacterales (CRE; n = 1718) and carbapenem-resistant, multidrug-resistant (MDR), and extensively drug-resistant Pseudomonas aeruginosa (n = 150) were the most common pathogens. Most publications reported positive outcomes for ceftazidime-avibactam treatment (clinical success rates ranged from 45 to 100% and reported 30-day mortality from 0 to 63%), which were statistically superior versus comparators in some studies. ceftazidime-avibactam resistance emergence occurred infrequently and mostly in Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae strains.

CONCLUSION

This review provides qualitative evidence of successful use of ceftazidime-avibactam for the treatment of hospitalised patients with CRE and MDR P. aeruginosa infections with limited treatment options.

Cefiderocol-Based Combination Therapy for "Difficult-to-Treat" Gram-Negative Severe Infections: Real-Life Case Series and Future Perspectives

Cefiderocol is a new cephalosporin displaying against extensively resistant (XDR) Gram-negative bacteria. We report our experience with cefiderocol-based combination therapies as “rescue” treatments in immunocompromised or critically ill patients or in patients with post-surgical infections who had failed previous regimens. A total of 13 patients were treated from 1 September 2020 to 31 March 2021. In total, 5/13 (38%) patients were classified as critically ill, due to severe COVID-19 lung failure; 4/13 (31%) patients had post-surgical infections and 4/13 (31%) had severe infections in immunocompromised subjects due to solid organ transplantation (2/4) or hematological malignancy (2/4). Overall, 10/13 infections were caused by carbapenem-resistant Acinetobacter baumannii, one by KPC-positive ceftazidime/avibactam-resistant Klebsiella pneumonia and two by Pseudomonas aeruginosa XDR. Based on clinical, microbiological and hematobiochemical evaluation, cefiderocol was associated with different companion drugs, particularly with fosfomycin, high-dose tigecycline and/or colistin. Microbiological eradication was achieved in all cases and the 30-day survival rate was 10/13; two patients died due to SARS-CoV-2 lung failure, whereas one death was attributed to subsequent infections. No recurrent infections within 30 days were reported. Finally, we hereby discuss the therapeutic potential of cefiderocol and the possible place in the therapy of this novel drug.

Carbapenem-Resistant Enterobacteriaceae-Implications for Treating Acute Leukemias, a Subgroup of Hematological Malignancies

Acute leukemias (AL) are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. Patients with AL are highly susceptible to infectious diseases due to the disease itself, factors attributed to treatment, and specific individual risk factors. Enterobacteriaceae presence (e.g., Klebsiella pneumonia and Escherichia coli) is a frequent cause of bloodstream infections in AL patients. Carbapenem-resistant Enterobacteriaceae (CRE) is an emerging health problem worldwide; however, the incidence of CRE varies greatly between different regions. Carbapenem resistance in Enterobacteriaceae is caused by different mechanisms, and CRE may display various resistance profiles. Bacterial co-expression of genes conferring resistance to both broad-spectrum β-lactam antibiotics (including carbapenems) and other classes of antibiotics may give rise to multidrug-resistant organisms (MDROs). The spread of CRE represents a major treatment challenge for clinicians due to lack of randomized clinical trials (RCTs), a limited number of antibiotics available, and the side-effects associated with them. Most research concerning CRE infections in AL patients are limited to case reports and retrospective reviews. Current research recommends treatment with older antibiotics, such as polymyxins, fosfomycin, older aminoglycosides, and in some cases carbapenems. To prevent the spread of resistant microbes, it is of pivotal interest to implement antibiotic stewardship to reduce broad-spectrum antibiotic treatment, but without giving too narrow a treatment to neutropenic infected patients.

A rare emergence of resistance to ceftolozane/tazobactam in Klebsiella pneumoniae causing urinary tract infection

The management of infections caused by carbapenem-resistant organisms has been a challenge. We report a rare emergence of resistance to the novel beta-lactam/ beta-lactamase combination ceftolozane/tazobactam by Klebsiella pneumoniae, causing urinary tract infection. The K. pneumoniae, in this case, was reported to be sensitive to the other novel beta-lactam/ beta-lactamase combination of ceftazidime/avibactam. The timely administration of ceftazidime/avibactam resulted in prompt clinical resolution of the urinary tract infection caused by an extensively drug-resistant K. pneumoniae.

Evaluating the clinical effectiveness of new beta-lactam/beta-lactamase inhibitor combination antibiotics: A systematic literature review and meta-analysis

Background:

Ceftazidime/avibactam (C/A), ceftolozane/tazobactam (C/T), imipenem/relebactam (I/R), and meropenem/vaborbactam (M/V) combine either a cephalosporin (C/T and C/A) or a carbapenem antibiotic (M/V and I/R) with a β-lactamase inhibitor. They are used to treat carbapenem-resistant Enterobacterales (CRE) and/or multidrug-resistant Pseudomonas aeruginosa (MDRPA).

Objective:

We compared the pooled clinical success of these medications to older therapies.

Methods:

PubMed and EMBASE were searched from January 1, 2012, through September 2, 2020, for C/A, C/T, I/R, and M/V studies. The main outcome was clinical success, which was assessed using random-effects models. Stratified analyses were conducted for study drug, sample size, quality, infection source, study design, and multidrug-resistant gram-negative organism (MDRGNO) population. Microbiological success and 28- and 30-day mortality were assessed as secondary outcomes. Heterogeneity was determined using I2 values.

Results:

Overall, 25 articles met the inclusion criteria; 8 observational studies and 17 randomized control trials. We detected no difference in clinical success comparing new combination antibiotics with standard therapies for all included organisms (pooled OR, 1.21; 95% CI, 0.96–1.51). We detected a moderate level of heterogeneity among the included studies I2 = 56%. Studies that focused on patients with CRE or MDRPA infections demonstrated a strong association between treatment with new combination antibiotics and clinical success (pooled OR, 2.20; 95% CI, 1.60–3.57).

Conclusions:

C/T, C/A, I/R, and M/V are not inferior to standard therapies for treating various complicated infections, but they may have greater clinical success for treating MDRPA and CRE infections. More studies that evaluate the use of these antibiotics for drug-resistant infections are needed to determine their effectiveness.

Acquired Genetic Elements that Contribute to Antimicrobial Resistance in Frequent Gram-Negative Causative Agents of Healthcare-Associated Infections

Antimicrobial resistance (AMR) is a worldwide public health problem that reduces therapeutic options and increases the risk of death. The causative agents of healthcare-associated infections (HAIs) are drug-resistant microorganisms of the nosocomial environment, which have developed different mechanisms of AMR. The hospital-associated microbiota has been proposed to be a reservoir of genes associated with AMR and an environment where the transfer of genetic material among organisms may occur. The ESKAPE group (Enterococcus faecalis and Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter aerogenes and Escherichia coli) is a frequent causative agents of HAIs. In this review, we address the issue of acquired genetic elements that contribute to AMR in the most frequent Gram-negative of ESKAPE, with a focus on last resort antimicrobial agents and the role of transference of genetic elements for the development of AMR.

Stewardship of Antibiotics for Multidrug-Resistant Gram-Negative Bacteria

Nearly one year ago, we wrote the following introductory note for authors willing to submit their paper to our Special Issue entitled "Stewardship of Antibiotics for Multidrug-Resistant Gram-Negative Bacteria" in Antibiotics: [...].