Clinical, microbiological characteristics and predictors of mortality in patients with carbapenemase-producing Enterobacterales bloodstream infections: a multicentre study

Risk factors, impact on outcomes, and molecular epidemiology of infections caused by carbapenem-resistant Enterobacterales in intensive care patients: a multicenter matched case-control study in Brazil

OBJECTIVE

To evaluate risk factors, molecular profiles, and hospital mortality of carbapenem-resistant Enterobacterales (CRE) infections in intensive care unit patients.

METHODS

In this retrospective, multicenter cohort study, intensive care unit admissions from 52 intensive care units between January 2019 and December 2020 were analyzed in a nested case-control design. Patients with carbapenem-resistant Enterobacterales infections were propensity score-matched 1:1 to those with carbapenem-susceptible Enterobacterales infections. Hierarchical conditional logistic regression identified risk factors for carbapenem-resistant Enterobacterales, and multivariable logistic regression assessed the association of carbapenem-resistant Enterobacterales with 60-day in-hospital mortality. Molecular genotyping was also conducted.

RESULTS

Matching resulted in 250 carbapenem-resistant Enterobacterales patients and 250 carbapenem-susceptible Enterobacterales patients. Sepsis was more common in the carbapenem-resistant Enterobacterales group (58% versus 35%; p < 0.001). Risk factors for carbapenem-resistant Enterobacterales included major premorbid assistance requirements (OR 1.72, 95%CI 0.99 - 3.01; p = 0.06) and intensive care unit readmission (OR 1.87, 95%CI 1.00 - 3.49; p = 0.05), although with weak associations. Acute COVID-19 (OR 3.55, 95%CI 1.96 - 6.45; p < 0.001) also increased the odds of resistance. Carbapenem-resistant Enterobacterales infection was associated with twice the likelihood of 60-day mortality after adjusting for covariates (OR 1.95, 95%CI 1.26 - 3.02; p < 0.001). The predominant bacteria and carbapenemase resistance genes included Klebsiella pneumoniae (79%), Klebsiella pneumoniae carbapenemase (73%), New Delhi metallo-beta-lactamase (13%), and xacillinase-48 (9%).

CONCLUSION

Carbapenem-resistant Enterobacterales-related infections in intensive care unit patients were associated with major premorbid dependence, intensive care unit readmission, and acute COVID-19. In addition, carbapenem-resistant Enterobacterales infections were independently associated with poorer hospital outcomes. This study also characterized the resistance profile of Enterobacterales in Brazilian intensive care units, which are dominated by K. pneumoniae with high rates of carbapenemase and increased rates of New Delhi metallo-beta-lactamase, in comparison with previous reports.

Targeted 'knock out' therapy with a combination antimicrobial regimen restores treatment options in the management of extensively drug-resistant carbapenemase-producing organisms

Introduction. Cefiderocol (FDC) and the combination of ceftazidime-avibactam and aztreonam (CZA+ATM) are emerging therapeutic options to combat carbapenemase-producing organisms (CPOs) that exhibit resistance due to multiple β-lactamases.Hypothesis/Gap Statement. Molecular diagnostics and specialized antimicrobial susceptibility testing (AST) are infrequently available in most clinical laboratories, and outputs from reference laboratories are not always timely. Practical methods must be explored to provide meaningful advice to treat infections due to CPOs in real time.Aim. To evaluate the in vitro efficacy of FDC and CZA+ATM against CPOs and to compare colistin (CST) MICs obtained locally with those from the reference laboratory.Methodology. CPOs isolated from 2017 to 2023 inclusive were retrieved. AST for FDC was performed using disc diffusion, CZA and ATM individually by E-tests and the E-test superposition method for the combination CZA+ATM. CST AST was performed locally using the VITEK2 system, and MICs were compared with those attained from the reference laboratory where manual broth microdilution is performed.Results. Fifty-eight CPOs were analysed. OXA-48 was the most frequently detected carbapenemase (37.9%, n=22). Co-existing β-lactamases of Ambler classes A and C were present for 79.3% of CPOs (n=46). Twenty-nine isolates (50%) were found to be susceptible to FDC. Fifty-seven isolates (98.3%) were susceptible to CST according to the VITEK2, compared to 44 of 47 tested isolates (93.6%) by the reference broth microdilution. Essential agreement was found to be 78.7%, and categorical agreement was 91.5% with one major error and three very major errors (VMEs) reported. CZA+ATM was tested against 26 CPOs, all of which harboured metallo-β-lactamases. Synergy was detected for all except one isolate where additivity was noted. Of the 32 isolates where combination therapy was not assessed, 29 (90.6%) possessed serine-β-lactamases and were susceptible to CZA monotherapy, whilst three (9.4%) possessed an isolated metallo-β-lactamase and were susceptible to ATM monotherapy.Conclusions. FDC appears to perform favourably against CPOs harbouring serine-β-lactamases, but not metallo-β-lactamases. The VITEK2 may provide presumptive categorical information for CST susceptibility, but MICs must be confirmed by broth microdilution as VMEs can lead to treatment failures. Moreover, our study confirms potent in vitro activity of CZA+ATM against CPOs expressing multiple β-lactamases.

Epidemiological and clinical characteristics of patients with carbapenem-resistant Enterobacterales in a university hospital of Colombia: Enzyme coproductions in rise

The distribution of carbapenemases in Carbapenem-Resistant Enterobacterales (CRE) has recently undergone a change in our region. According to the Colombian National Institute of Health, there is an increasing prevalence of NDM and NDM-KPC co-producing strains. We carried-out an ambispective cohort study of adult inpatients from Hospital Universitario San Ignacio (2021-2023), infected or colonized with CRE, in which carbapenemases immunochromatographic assay was performed. Out of the 150 patients included in the study, 71.3 % presented with an infection, and carbapenemases were detected in 92.7 % of these cases. Among them, KPC predominated (54 %), while 16.7 % demonstrated enzyme coproductions, mainly KPC-NDM. CRE infected patients had an 18.7 % 30-days mortality, but we could not demonstrate an association between type of carbapenemase and mortality rate (p = 0.82). Logistic regression analysis suggested that ICU admission was independently correlated to fatality (OR 5.08; CI 1.68-16.01). NDM and KPC-NDM presence in CRE poses a public health threat and a therapeutic challenge, with unknown mortality differences according to the carbapenemases pattern. Nevertheless, there was not an association between enzyme type and mortality.

Clinical and Microbiological Risk Factors for 30-Day Mortality of Bloodstream Infections Caused by OXA-48-Producing Klebsiella pneumoniae

Bloodstream infections (BSI) caused by carbapenem-resistant Klebsiella pneumoniae are associated with high morbidity and mortality, and the therapy options available for their treatment are frequently scarce. The aim of this study was to analyze risk factors for 30-day mortality in patients with BSI caused by OXA-48-producing K. pneumoniae. The clinical and treatment features of the patients, who attended a single hospital over a five-year period, were retrospectively reviewed. The microbiological features, including the sequence types (ST) and the somatic (O) and capsular (K) antigens, as well as their resistance properties, comprising phenotypes and genetic background, were also considered. To identify the risk factors for 30-day mortality, uni- and multivariate statistical analyses were performed. The univariate analysis revealed statistically significant correlations for age, male gender, lower respiratory system infection, infection by ST147 isolates, and infection by isolates expressing the K64 antigen. The multivariate analysis, applied to variables yielding p-values close to or lower than 0.05 in the univariate analysis, confirmed gender, lower respiratory system infection, and infection with ST147 isolates, but not age or infection with K64 isolates, as risk factors for 30-day mortality. Moreover, the multivariate analysis showed that patients suffering from hematological malignancies or having been treated with inappropriate therapy, both having p-values slightly higher than 0.05 in the univariate analysis, exhibited significantly poorer outcomes in the multivariant analysis. The association of the ST147 clone with an increased risk of mortality is a novel finding that deserves further attention. Studies like the one presented here can certainly benefit the management of patients with nosocomial BSI caused by carbapenemase-producing K. pneumoniae.