Infections caused by KPC-producing Klebsiella pneumoniae: differences in therapy and mortality in a multicentre study

Systematic Review of Beta-Lactam vs. Beta-Lactam plus Aminoglycoside Combination Therapy in Neutropenic Cancer Patients

We performed a systematic review of studies that compared beta-lactams vs. beta-lactams plus aminoglycosides for the treatment of febrile neutropenia in cancer patients.

METHOD

We searched CENTRAL, MEDLINE, and Embase for studies published up to October 2023, and randomized controlled trials (RCTs) that compared anti-Pseudomonas aeruginosa beta-lactam monotherapy with any combination of an anti-Pseudomonas aeruginosa beta-lactam and an aminoglycoside were included.

RESULT

The all-cause mortality rate of combination therapy showed no significant differences compared with that of monotherapy (RR 0.99, 95% CI 0.84 to 1.16, high certainty of evidence). Infection-related mortality rates showed that combination therapy had a small positive impact compared with the intervention with monotherapy (RR 0.83, 95% CI 0.66 to 1.05, high certainty of evidence). Regarding treatment failure, combination therapy showed no significant differences compared with monotherapy (RR 0.99, 95% CI 0.94 to 1.03, low certainty of evidence). In the sensitivity analysis, the treatment failure data published between 2010 and 2019 showed better outcomes in the same beta-lactam group (RR 1.10 [95% CI, 1.01-1.19]). Renal failure was more frequent with combination therapy of any daily dosing regimen (RR 0.46, 95% CI 0.36 to 0.60, high certainty of evidence).

CONCLUSION

We found combining aminoglycosides with a narrow-spectrum beta-lactam did not spare the use of broad-spectrum antibiotics. Few studies included antibiotic-resistant bacteria and a detailed investigation of aminoglycoside serum levels, and studies that combined the same beta-lactams showed only a minimal impact with the combination therapy. In the future, studies that include the profile of antibiotic-resistant bacteria and the monitoring of serum aminoglycoside levels will be required.

Clinical outcomes and risk factors for mortality in recipients with carbapenem-resistant gram-negative bacilli infections after kidney transplantation treated with ceftazidime-avibactam: a retrospective study

Background

Ceftazidime-avibactam is a treatment option for carbapenem-resistant gram-negative bacilli (CR-GNB) infections. However, the risk factors associated with ceftazidime-avibactam (CAZ-AVI) treatment failure in kidney transplant (KT) recipients and the need for CAZ-AVI-based combination therapy remain unclear.

Methods

From June 2019 to December 2023, a retrospective observational study of KT recipients with CR-GNB infection treated with CAZ-AVI was conducted, with the primary outcome being 30-day mortality and secondary outcomes being clinical cure, microbiological cure, and safety. Risk factors for 30-day mortality and clinical failure were also investigated.

Results

A total of 81 KT recipients treated with CAZ-AVI were included in this study. Forty recipients (49.4%) received CAZ-AVI monotherapy, with a 30-day mortality of 22.2%. The clinical cure and microbiological cure rates of CAZ/AVI therapy were 72.8% and 66.7%, respectively. CAZ-AVI alone or in combination with other medications had no effect on clinical cure or 30-day mortality. Multivariate logistic regression analysis revealed that a higher Acute Physiology and Chronic Health Evaluation (APACHE) II score (odds ratio [OR]: 4.517; 95% confidence interval [CI]: 1.397-14.607; P = 0.012) was an independent risk factor for 30-day mortality. Clinical cure was positively associated with the administration of CAZ-AVI within 48 hours of infection onset (OR: 11.009; 95% CI: 1.344-90.197; P=0.025) and negatively associated with higher APACHE II scores (OR: 0.700; 95% CI: 0.555-0.882; P=0.002). Four (4.9%) recipients experienced recurrence within 90 days after the initial infection, 3 (3.7%) recipients experienced CAZ-AVI-related adverse events, and no CAZ-AVI resistance was identified.

Conclusion

CAZ-AVI is an effective medication for treating CR-GNB infections following kidney transplantation, even as monotherapy. Optimization of CAZ/AVI therapy (used within 48 hours of infection onset) is positively associated with potential clinical benefit. Further larger-scale studies are needed to validate these findings.

Risk factors of Carbapenem-resistant Enterobacterales intestinal colonization for subsequent infections in hematological patients: a retrospective case-control study

Objective

Infections caused by Carbapenem-resistant Enterobacterales (CRE) have high treatment costs, high mortality and few effective therapeutic agents. This study aimed to determine the risk factors for progression from intestinal colonization to infection in hematological patients and the risk factors for 30-day mortality in infected patients.

Methods

A retrospective case-control study was conducted in the Department of Hematology at Shandong Provincial Hospital affiliated to Shandong First Medical University from April 2018 to April 2022. Patients who developed subsequent infections were identified as the case group by electronic medical record query of patients with a positive rectal screen for CRE colonization, and patients who did not develop subsequent infections were identified as the control group by stratified random sampling. Univariate analysis and logistic regression analysis determined risk factors for developing CRE infection and risk factors for mortality in CRE-infected patients.

Results

Eleven hematological patients in the study developed subsequent infections. The overall 30-day mortality rate for the 44 hematological patients in the case-control study was 11.4% (5/44). Mortality was higher in the case group than in the control group (36.5 vs. 3.0%, P = 0.0026), and septic shock was an independent risk factor for death (P = 0.024). Univariate analysis showed that risk factors for developing infections were non-steroidal immunosuppressants, serum albumin levels, and days of hospitalization. In multivariable logistic regression analysis, immunosuppressants [odds ratio (OR), 19.132; 95% confidence interval (CI), 1.349-271.420; P = 0.029] and serum albumin levels (OR, 0.817; 95% CI, 0.668-0.999; P = 0.049) were independent risk factors for developing infections.

Conclusion

Our findings suggest that septic shock increases mortality in CRE-infected hematological patients. Hematological patients with CRE colonization using immunosuppressive agents and reduced serum albumin are more likely to progress to CRE infection. This study may help clinicians prevent the onset of infection early and take measures to reduce mortality rates.

Carbapenem-resistant Gram-negative bacteria (CR-GNB) in ICUs: resistance genes, therapeutics, and prevention - a comprehensive review

Intensive care units (ICUs) are specialized environments dedicated to the management of critically ill patients, who are particularly susceptible to drug-resistant bacteria. Among these, carbapenem-resistant Gram-negative bacteria (CR-GNB) pose a significant threat endangering the lives of ICU patients. Carbapenemase production is a key resistance mechanism in CR-GNB, with the transfer of resistance genes contributing to the extensive emergence of antimicrobial resistance (AMR). CR-GNB infections are widespread in ICUs, highlighting an urgent need for prevention and control measures to reduce mortality rates associated with CR-GNB transmission or infection. This review provides an overview of key aspects surrounding CR-GNB within ICUs. We examine the mechanisms of bacterial drug resistance, the resistance genes that frequently occur with CR-GNB infections in ICU, and the therapeutic options against carbapenemase genotypes. Additionally, we highlight crucial preventive measures to impede the transmission and spread of CR-GNB within ICUs, along with reviewing the advances made in the field of clinical predictive modeling research, which hold excellent potential for practical application.

Antimicrobial and Diagnostic Stewardship of the Novel β-Lactam/β-Lactamase Inhibitors for Infections Due to Carbapenem-Resistant Enterobacterales Species and Pseudomonas aeruginosa

Carbapenem-resistant Gram-negative bacterial infections are a major public health threat due to the limited therapeutic options available. The introduction of the new β-lactam/β-lactamase inhibitors (BL/BLIs) has, however, altered the treatment options for such pathogens. Thus, four new BL/BLI combinations-namely, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, and ceftolozane/tazobactam-have been approved for infections attributed to carbapenem-resistant Enterobacterales species and Pseudomonas aeruginosa. Nevertheless, although these antimicrobials are increasingly being used in place of other drugs such as polymyxins, their optimal clinical use is still challenging. Furthermore, there is evidence that resistance to these agents might be increasing, so urgent measures should be taken to ensure their continued effectiveness. Therefore, clinical laboratories play an important role in the judicious use of these new antimicrobial combinations by detecting and characterizing carbapenem resistance, resolving the presence and type of carbapenemase production, and accurately determining the minimum inhibitor concentrations (MICs) for BL/BLIs. These three targets must be met to ensure optimal BL/BLIs use and prevent unnecessary exposure that could lead to the development of resistance. At the same time, laboratories must ensure that results are interpreted in a timely manner to avoid delays in appropriate treatment that might be detrimental to patient safety. Thus, we herein present an overview of the indications and current applications of the new antimicrobial combinations and explore the diagnostic limitations regarding both carbapenem resistance detection and the interpretation of MIC results. Moreover, we suggest the use of alternative narrower-spectrum antibiotics based on susceptibility testing and present data regarding the effect of synergies between BL/BLIs and other antimicrobials. Finally, in order to address the absence of a standardized approach to using the novel BL/BLIs, we propose a diagnostic and therapeutic algorithm, which can be modified based on local epidemiological criteria. This framework could also be expanded to incorporate other new antimicrobials, such as cefiderocol, or currently unavailable BL/BLIs such as aztreonam/avibactam and cefepime/taniborbactam.

Critical role of growth medium for detecting drug interactions in Gram-negative bacteria that model in vivo responses

The rise in infections caused by multidrug-resistant (MDR) bacteria has necessitated a variety of clinical approaches, including the use of antibiotic combinations. Here, we tested the hypothesis that drug-drug interactions vary in different media, and determined which in vitro models best predict drug interactions in the lungs. We systematically studied pair-wise antibiotic interactions in three different media, CAMHB, (a rich lab medium standard for antibiotic susceptibility testing), a urine mimetic medium (UMM), and a minimal medium of M9 salts supplemented with glucose and iron (M9Glu) with three Gram-negative ESKAPE pathogens, Acinetobacter baumannii (Ab), Klebsiella pneumoniae (Kp), and Pseudomonas aeruginosa (Pa). There were pronounced differences in responses to antibiotic combinations between the three bacterial species grown in the same medium. However, within species, PaO1 responded to drug combinations similarly when grown in all three different media, whereas Ab17978 and other Ab clinical isolates responded similarly when grown in CAMHB and M9Glu medium. By contrast, drug interactions in Kp43816, and other Kp clinical isolates poorly correlated across different media. To assess whether any of these media were predictive of antibiotic interactions against Kp in the lungs of mice, we tested three antibiotic combination pairs. In vitro measurements in M9Glu, but not rich medium or UMM, predicted in vivo outcomes. This work demonstrates that antibiotic interactions are highly variable across three Gram-negative pathogens and highlights the importance of growth medium by showing a superior correlation between in vitro interactions in a minimal growth medium and in vivo outcomes.

IMPORTANCE

Drug-resistant bacterial infections are a growing concern and have only continued to increase during the SARS-CoV-2 pandemic. Though not routinely used for Gram-negative bacteria, drug combinations are sometimes used for serious infections and may become more widely used as the prevalence of extremely drug-resistant organisms increases. To date, reliable methods are not available for identifying beneficial drug combinations for a particular infection. Our study shows variability across strains in how drug interactions are impacted by growth conditions. It also demonstrates that testing drug combinations in tissue-relevant growth conditions for some strains better models what happens during infection and may better inform combination therapy selection.

Within-species variability of antibiotic interactions in Gram-negative bacteria

Treatments with antibiotic combinations are becoming increasingly important even though the supposed clinical benefits of combinations are, in many cases, unclear. Here, we systematically examined how several clinically used antibiotics interact and affect the antimicrobial efficacy against five especially problematic Gram-negative pathogens. A total of 232 bacterial isolates were tested against different pairwise antibiotic combinations spanning five classes, and the ability of all combinations in inhibiting growth was quantified. Descriptive statistics, principal component analysis (PCA), and Spearman's rank correlation matrix were used to determine the correlations between the different combinations on interaction outcome. Several important conclusions can be drawn from the 696 examined interactions. Firstly, within a species, the interactions are in general conserved but can be isolate-specific for a given antibiotic combination and can range from antagonistic to synergistic. Secondly, additive and antagonistic interactions are the most common observed across species and antibiotics, with 87.1% of isolate-antibiotic combinations being additive, 11.6% antagonistic, and only 0.3% showing synergy. These findings suggest that to achieve the highest precision and efficacy of combination therapy, not only isolate-specific interaction profiling ought to be routinely performed, in particular to avoid using drug combinations that show antagonistic interaction and an expected associated reduction in efficacy, but also discovering rare and potentially valuable synergistic interactions.IMPORTANCEAntibiotic combinations are often used to treat bacterial infections, which aim to increase treatment efficacy and reduce resistance evolution. Typically, it is assumed that one specific antibiotic combination has the same effect on different isolates of the same species, i.e., the interaction is conserved. Here, we tested this idea by examining how several clinically used antibiotics interact and affect the antimicrobial efficacy against several bacterial pathogens. Our results show that, even though within a species the interactions are often conserved, there are also isolate-specific differences for a given antibiotic combination that can range from antagonistic to synergistic. These findings suggest that isolate-specific interaction profiling ought to be performed in clinical microbiology routine to avoid using antagonistic drug combinations that might reduce treatment efficacy.

Characteristics of Klebsiella pneumoniae pyogenic liver abscess from 2010-2021 in a tertiary teaching hospital of South China

OBJECTIVES

Pyogenic liver abscess (PLA) is a severe and potentially fatal infectious disease. Klebsiella pneumoniae (K. pneumoniae) is the predominant pathogen responsible for PLA. This study aims to investigate the clinical characteristics and prognostic factors of K. pneumoniae-induced pyogenic liver abscess (KP-PLA), particularly those caused by carbapenem-resistant K. pneumoniae (CRKP).

METHODS

Analyses were performed on PLA patients from January 2010 to December 2021, to investigate the differences of K. pneumoniae from other etiologically infected PLA patients. Univariate and multivariate logistic regression analyses were used to compare prognostic factors between patients with carbapenem-resistant K. pneumoniae PLA (CRKP-PLA) and patients with carbapenem-sensitive K. pneumoniae PLA.

RESULTS

Univariate analysis demonstrated a significant association between KP-PLA and factors including diabetes mellitus (P < 0.001), cholecystitis and cholelithiasis (P = 0.032), single abscess (P = 0.016), and abscesses with a diameter over 50 mm (P = 0.004). The CRKP group exhibited a higher prevalence of therapeutic interventions before K. pneumoniae infection, including abdominal surgery, mechanical ventilation, sputum suction, tracheal cannula, routine drainage of the abdominal cavity, and peripherally inserted central venous catheters (P < 0.05). Multivariate logistic regression analysis revealed that admission to the intensive care unit was an independent risk factor associated with CRKP-PLA (odds ratio 36; 95% confidence interval 1.77-731.56; P = 0.020).

CONCLUSION

The KP-PLA patients were significantly associated with diabetes and were more likely to have single abscesses larger than 50 mm. PLA patients with a history of admission to intensive care unit or invasive therapeutic procedures should be given special consideration if combined with CRKP infection.

Association of Diabetes Mellitus With Increased Mortality in Carbapenem-Resistant Enterobacterales Infections

Introduction Carbapenem-resistant Enterobacterales (CRE) infections have high mortality. We aimed to examine the diabetes mellitus (DM) association with CRE mortality. Methodology Our study is a retrospective cohort study including patients who were admitted to the medical wards in the main district hospital (New Jahra Hospital, Kuwait) between January 1, 2022, and January 1, 2023, and diagnosed with CRE infections during hospitalization. The patients were divided into diabetic and non-diabetic groups. Clinical and laboratory data were collected. The presence of carbapenemase genes was detected. The primary outcome was 30-day hospital mortality. We assessed the effect of glycemic control on the outcomes. Results We included 47 patients in the diabetic group and 39 patients in the non-diabetic group. Females represented 54.7% of patients, and the median age was 73 and 55 years in the two groups, respectively. Klebsiella pneumonia (86%) and Escherichia coli (12.8%) were the most frequently isolated CRE. Carbapenemase genes were detected in all patients: NDM-1 in 67.4%, OXA-48 in 18.6%, and both genes coexisted in 14%. The 30-day hospital mortality was significantly higher in the diabetic group compared to the non-diabetic group (48.9% vs. 28.2%, P = 0.041). Among the diabetic patients, there was no significant difference between survivors and non-survivors regarding median glucose or glycated hemoglobin (HbA1c) levels (P = 0.465 and 0.932, respectively). Moreover, levels of glucose (odds ratio (OR) 0.928, confidence interval (CI) 0.763-1.13, P = 0.457) and HbA1c (OR 0.89, CI 0.63-1.26, P = 0.507) were not risk factors for increased mortality among diabetic patients.  Conclusion We demonstrated the association between DM and increased CRE mortality regardless of the level of glycemic control. This study demonstrates the interaction between communicable and non-communicable diseases.

Attributable mortality of infections caused by carbapenem-resistant Enterobacterales: results from a prospective, multinational case-control-control matched cohorts study (EURECA)

OBJECTIVES

To assess the mortality attributable to infections caused by carbapenem-resistant Enterobacterales (CRE) and to investigate the effect of clinical management on differences in observed outcomes in a multinational matched cohort study.

METHODS

A prospective matched-cohorts study (NCT02709408) was performed in 50 European hospitals from March 2016 to November 2018. The main outcome was 30-day mortality with an active post-discharge follow-up when applied. The CRE cohort included patients with complicated urinary tract infections, complicated intra-abdominal infections, pneumonia, or bacteraemia from other sources because of CRE. Two control cohorts were selected: patients with infection caused by carbapenem-susceptible Enterobacterales (CSE) and patients without infection. Matching criteria included type of infection for the CSE group, hospital ward of CRE detection, and duration of hospital admission up to CRE detection. Multivariable and stratified Cox regression was applied.

RESULTS

The cohorts included 235 patients with CRE infection, 235 patients with CSE infection, and 705 non-infected patients. The 30-day mortality (95% CI) was 23.8% (18.8-29.6), 10.6% (7.2-15.2), and 8.4% (6.5-10.6), respectively. The difference in 30-day mortality rates between patients with CRE infection when compared with patients with CSE infection was 13.2% (95% CI, 6.3-20.0), (HR, 2.57; 95% CI, 1.55-4.26; p < 0.001), and 15.4% (95% CI, 10.5-20.2) when compared with non-infected patients (HR, 3.85; 95% CI, 2.57-5.77; p < 0.001). The population attributable fraction for 30-day mortality for CRE vs. CSE was 19.28%, and for CRE vs. non-infected patients was 9.61%. After adjustment for baseline variables, the HRs for mortality were 1.87 (95% CI, 0.99-3.50; p 0.06) and 3.65 (95% CI, 2.29-5.82; p < 0.001), respectively. However, when treatment-related time-dependent variables were added, the HR of CRE vs. CSE reduced to 1.44 (95% CI, 0.78-2.67; p 0.24).

DISCUSSION

CRE infections are associated with significant attributable mortality and increased adjusted hazard of mortality when compared with CSE infections or patients without infection. Underlying patient characteristics and a delay in appropriate treatment play an important role in the CRE mortality.

How to tailor recommendations on the treatment of multi-drug resistant Gram-negative infections at country level integrating antibiotic stewardship principles within the GRADE-ADOLOPMENT framework

Promoting the optimal use of antibiotics through evidence-based recommendations should be regarded as a crucial step in the global fight against antimicrobial resistance. Within this scope, several guidelines and guidance documents for antibiotic therapy have been published in recent years. All documents underline the limitations of existing evidence and remark on the need for tailoring recommendations at the national level, based on local epidemiology, availability of diagnostics and drugs, and antimicrobial stewardship principles. The GRADE-ADOLOPMENT methodology is an evidence-based methodology that allows the adoption, adaptation, and update of existing recommendations to specific settings without performing de novo systematic reviews and grading of the evidence. However, procedures to integrate this evidence with stewardship principles, countries' surveillance data, and capacity in terms of diagnostics and antibiotics' availability have never been defined. This Personal View provides the first example of a country's calibration of international evidence-based guidance documents on treating infections caused by multidrug-resistant bacteria. A panel of experts convened by the Italian Medicine Agency (AIFA) used the GRADE methodology for systematically extracting and evaluating 100 recommendations on the treatment of infections due to multidrug-resistant Gram-negative bacteria from 11 guidance documents and 24 systematic reviews. The ADOLOPMENT procedure was used to calibrate the existing recommendations to the national context, leading to the adoption of 64, the adaptation of 27, and the rejection of nine recommendations. We discuss the technical details of the GRADE-ADOLOPMENT application, the calibration process, and the human resources required to support such an effort. This Personal View also covers the challenges of integrating antibiotic stewardship principles in evidence-based recommendations for treating infections with very limited therapeutic and diagnostic options. The details presented here could support the easy transferability of the methodology to other countries and settings, particularly where the incidence of antibiotic-resistant infections is high.

Carbapenem-resistant Klebsiella pneumoniae bloodstream infections in haematological malignances and hematopoietic stem cell transplantation: Clinical impact of combination therapy in a 10-year Brazilian cohort

Bacterial bloodstream infections (BSI) are a common threat among patients with haematological malignancies (HM) and hematopoietic stem cell transplant recipients (HSCT). The purpose of this research was to describe clinical and microbiological aspects of BSI caused by carbapenem-resistant Klebsiella pneumoniae (CRKp) and assess risk factors associated with 30-day mortality in a 10-year cohort of haematological patients. A total of 65 CRKp-BSI episodes occurring in HM patients and HSCT recipients and CRKp-BSI between January 2010 and December 2019 were retrospectively studied. Acute leukemias were the most frequently observed underlying disease (87.7%) and 18 patients (27.7%) received HSCT. Mucosal barrier injury in the gastrointestinal tract was the primary cause of bacteremia (86.1%). Also, 14 individuals (21.6%) had an Invasive Fungal Disease (IFD) throughout the episode. Regarding treatment, in 31 patients (47.7%) empirical therapy was deemed appropriate, whereas 33 (50.8%) patients received a combination therapy. Microbiological data revealed that the majority of isolates (53-58%) had the Polymyxin B co-resistance phenotype, while amikacin resistance was less common (16 samples, or 24.7%). The mortality rates at 14 and 30 days were 32.3% and 36.9%, respectively. In a multivariate Cox regression analysis, prompt appropriate antibiotic administration within three days was associated with a better outcome (Adjusted Hazard Ratio [aHR]: 0.33; 95% Confidence Interval [CI]: 0.14-0.76; p = 0.01), whereas hypotension at presentation (aHR: 3.88; 95% CI: 1.40-10.74; p = 0.01) and concurrent IFD (aHR: 2.97; 95% CI: 1.20-7.37; p = 0.02) were independently associated with death within 30 days. Additionally, a favorable correlation between combination therapy and overall survival was found (aHR: 0.18; 95%CI: 0.06-0.56; p = 0.002). In conclusion, 30-day mortality CRKp-BSI was elevated and most of the isolates were polymyxin B resistant. Early appropriate antimicrobial treatment and the use of combination therapy were linked to a better outcome.

Clinical Outcomes and Risk Factors for Death in Critically Ill Patients with Carbapenem-Resistant Klebsiella pneumoniae Treated with Ceftazidime-Avibactam: A Retrospective Study

Purpose

Carbapenem-Resistant Klebsiella pneumoniae (CRKP) is a significant public health threat, because it is associated with substantial morbidity and mortality. However, the risk factors associated with treatment failure of ceftazidime-avibactam (CAZ-AVI) and the need for CAZ-AVI-based combination remain unclear.

Methods

We conducted a retrospective study of critically ill patients (age: > 18 years) diagnosed with CRKP infections and treated with CAZ-AVI for at least 24 h between June 2020 and December 2022 at Henan Provincial People's Hospital.

Results

This study included a total of 103 patients who received CAZ-AVI. Of these, 91 (88.3%) patients received the standard dosage of 2.5 g every q8h, while only 20 (19.4%) received monotherapy. The Kaplan-Meier curves showed that the all-cause 30-day mortality was significantly higher among patients who experienced septic shock than those who did not. There was no significant difference in mortality between monotherapy and combination therapy. Dose reduction of CAZ-AVI was associated with a significantly increased mortality rate. Independent risk factors for the 30-day mortality included higher APACHE II score (HR: 1.084, 95% CI: 1.024-1.147, p = 0.005) and lower lymphocyte count (HR: 0.247, 95% CI: 0.093-0.655, p = 0.005). Conversely, a combination therapy regimen containing carbapenems was associated with lower mortality (HR: 0.273, 95% CI: 0.086-0.869, p = 0.028).

Conclusion

Our study suggests that CAZ-AVI provides clinical benefits in terms of survival and clinical response in critically ill patients with CRKP infection. A higher APACHE II score and lower lymphocyte count were associated with 30-day mortality, while the combination therapy regimen containing carbapenems was the only protective factor. CAZ-AVI dose reduction was associated with an increased mortality rate. Futher large-scale studies are needed to validate these findings.

Treatment and diagnosis of severe KPC-producing Klebsiella pneumoniae infections: a perspective on what has changed over last decades

Antimicrobial resistance is a global health threat. Among Gram-negative bacteria, resistance to carbapenems, a class of β-lactam antibiotics, is usually a proxy for difficult-to-treat resistance, since carbapenem-resistant organisms are often resistant to many classes of antibiotics. Carbapenem resistance in the Gram-negative pathogen Klebsiella pneumoniae is mostly due to the production of carbapenemases, enzymes able to hydrolyze carbapenems, and K. pneumoniae carbapenemase (KPC)-type enzymes are overall the most prevalent carbapenemases in K. pneumoniae. In the last decade, the management of severe infections due to KPC-producing K. pneumoniae (KPC-Kp) in humans has presented many peculiar challenges to clinicians worldwide. In this perspective, we discuss how the treatment of severe KPC-Kp infections has evolved over the last decades, guided by the accumulating evidence from clinical studies, and how recent advances in diagnostics have allowed to anticipate identification of KPC-Kp in infected patients.KEY MESSAGESIn the last decade, the management of severe infections due to KPC-Kp has presented many peculiar challenges to clinicians worldwideFollowing the introduction in clinical practice of novel β-lactam/β-lactamase inhibitor combinations and novel β-lactams active against KPC-producing bacteria, the management of severe KPC-Kp infections has witnessed a remarkable evolutionTreatment of severe KPC-Kp infections is a highly dynamic process, in which the wise use of novel antimicrobials should be accompanied by a continuous refinement based on evolving clinical evidence and laboratory diagnostics.

Clinical and Microbiological Characteristics of Klebsiella pneumoniae Co-Infections in Pulmonary Tuberculosis: A Retrospective Study

Background

Klebsiella pneumoniae (K. pneumoniae) is one of the most common pathogens leading to pulmonary tuberculosis (PTB) co-infection, but the data of co-infections is scarce. This research aimed to study the clinical and microbiological characteristics of K. pneumoniae co-infections in pulmonary tuberculosis cases.

Methods

Clinical manifestations and examination results of PTB cases co-infected by K. pneumoniae were retrospectively collected from the medical record database of a tertiary teaching hospital in China between November 2019 and October 2021. The K. pneumoniae strains isolated from the patients were sent for whole-genome sequencing. Statistical analyses were conducted using Stata v.14.0.

Results

A total of 80 strains were collected from 76 PTB patients with K. pneumoniae co-infections (two strains were isolated from each of the four patients at different time points), including 37 primary and 39 retreated TB cases. Among these, 29 (36.3%) of the K. pneumoniae isolates were extended-spectrum β-lactamase (ESBL)-producing strains, and seven (8.8%) were determined as carbapenem-resistant Enterobacteriaceae (CRE) strains. We found that patients in the multidrug resistance (MDR)-group received more respiratory support than the non-MDR group (40.6% vs 18.2%, P= 0.031) and possessed higher elevated C-reactive protein (62.6% vs 41.8%, P=0.008) and lower haemoglobin (87.5% vs 47.7%, P=0.001). We found that 80.3% (61/76) patients had lung lesions and 57.8% (44/76) patients were immunocompromised within one month. The most common K. pneumoniae strain sequence type was ST23 (15%), followed by ST15 (12.5%) and ST273 (7.5%). Among the strains, 26.25% were classically hypervirulent K1/K2 K. pneumoniae, and all carried salmochelin and rmpA.

Conclusion

This study demonstrated the important clinical features, phenotypic and genomic characteristics of isolated strains of PTB patients with K. pneumoniae co-infection. These data suggested a special attention for multidrug resistant K. pneumoniae infections with more obvious inflammatory responses which calls for more respiratory support and timely clinical management.

Antimicrobial Activities of Aztreonam-Avibactam and Comparator Agents against Enterobacterales Analyzed by ICU and Non-ICU Wards, Infection Sources, and Geographic Regions: ATLAS Program 2016-2020

Increasing antimicrobial resistance among multidrug-resistant (MDR), extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing Enterobacterales (CPE), in particular metallo-β-lactamase (MBL)-positive strains, has led to limited treatment options in these isolates. This study evaluated the activity of aztreonam-avibactam (ATM-AVI) and comparator antimicrobials against Enterobacterales isolates and key resistance phenotypes stratified by wards, infection sources and geographic regions as part of the ATLAS program between 2016 and 2020. Minimum inhibitory concentrations (MICs) were determined per Clinical and Laboratory Standards Institute (CLSI) guidelines. The susceptibility of antimicrobials were interpreted using CLSI and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. A tentative pharmacokinetic/pharmacodynamic breakpoint of 8 µg/mL was considered for ATM-AVI activity. ATM-AVI inhibited ≥99.2% of Enterobacterales isolates across wards and ≥99.7% isolates across infection sources globally and in all regions at ≤8 µg/mL. For resistance phenotypes, ATM-AVI demonstrated sustained activity across wards and infection sources by inhibiting ≥98.5% and ≥99.1% of multidrug-resistant (MDR) isolates, ≥98.6% and ≥99.1% of ESBL-positive isolates, ≥96.8% and ≥90.9% of carbapenem-resistant (CR) isolates, and ≥96.8% and ≥97.4% of MBL-positive isolates, respectively, at ≤8 µg/mL globally and across regions. Overall, our study demonstrated that ATM-AVI represents an important therapeutic option for infections caused by Enterobacterales, including key resistance phenotypes across different wards and infection sources.

Clinical outcomes in elderly patients with infections caused by NDM-producing Klebsiella pneumoniae: results from a real-life retrospective single center study in an endemic area

Real-life outcomes data for elderly patients with infections caused by Klebsiella pneumoniae producing New Delhi metallo-beta-lactamase (NDM-Kp) are lacking. We conducted a retrospective cohort study enrolling 33 consecutive adult patients (mean age 77.4 years; 48.5% males; mean Charlson Comorbidity Index-CCI 5.9) hospitalized for NDM-Kp infections during a 24-month period in an Italian highly endemic area. 78.8% were admitted to Internal Medicine ward. 45.4% of patients had bloodstream infections (BSI), 39.4% urinary tract infections (UTI) without BSI, 9.1% respiratory tract infections and 6.1% intra-abdominal infections. 93.9% had rectal colonization.Adequate definitive antibiotic therapy (mainly represented by aztreonam plus ceftazidime/avibactam) was provided to 36.4% of cases. Mean age and CCI of patients adequately treated were significantly lower than those inadequately treated (71.2 vs 80.9 years, p = 0.041, and 4.6 vs 6.7, p = 0.040, respectively). Patients adequately treated had a mean hospitalization length significantly higher (28 vs 15 days, p = 0.016). The overall 30-day survival rate of patients adequately and inadequately treated was 83.3% and 57.1%, respectively: this difference was not statistically significant. Mean age and CCI of 22 patients who survived at 30 days were lower than those of 11 patients who died (73.7 vs 84.8 years, p = 0.003, and 5.3 vs 7.2, p = 0.049, respectively). Twelve survivors received an inadequate therapy: 8/12 had UTI. Six of nine patients inadequately treated who died within 30 days, died before microbiological diagnosis. Our study provides real-life data on outcomes of elderly and multimorbid patients hospitalized for infections caused by NDM-Kp. Further studies with larger sample size are warranted.

Mortality in KPC-producing Klebsiella pneumoniae bloodstream infections: a changing landscape

OBJECTIVES

To assess the impact of carbapenem resistance on mortality in Klebsiella pneumoniae bloodstream infection (BSI) in the era of novel β-lactam/β-lactamase inhibitor combinations.

MATERIAL AND METHODS

Retrospective study of patients with K. pneumoniae BSI between January and August 2020 in 16 centres (CARBANEW study within the MULTI-SITA project).

RESULTS

Overall, 426 patients were included: 107/426 (25%) had carbapenem-resistant K. pneumoniae (CR-Kp) BSI and 319/426 (75%) had carbapenem-susceptible K. pneumoniae (CS-Kp) BSI. Crude cumulative 30 day mortality was 33.8% and 20.7% in patients with, respectively, CR-Kp BSI and CS-Kp BSI (P = 0.027). Carbapenemase production or carbapenemase-encoding genes were detected in 84/98 tested CR-Kp isolates (85.7%), mainly KPC (78/84; 92.9%). Ceftazidime/avibactam was the most frequently used appropriate therapy for CR-Kp BSI (80/107; 74.7%). In multivariable analyses, variables showing an unfavourable association with mortality after correction for multiple testing were age-adjusted Charlson comorbidity index (HR 1.20; 95% CI 1.10-1.31, P < 0.001) and Pitt score (HR 1.33; 95% CI 1.15-1.55, P < 0.001), but not carbapenem resistance (HR 1.28, 95% CI 0.74-2.22, P = 0.410). In a propensity score-matched analysis, there was no difference in mortality between patients appropriately treated with ceftazidime/avibactam for CR-Kp BSI and patients appropriately treated with other agents (mainly meropenem monotherapy or piperacillin/tazobactam monotherapy) for CS-Kp BSI (HR 1.07; 95% CI 0.50-2.29, P = 0.866).

CONCLUSIONS

Our results suggest that the increased mortality in CR-Kp BSI compared with CS-Kp BSI is not (or no longer) dependent on the type of therapy in areas where ceftazidime/avibactam-susceptible KPC-producing isolates are the most prevalent type of CR-Kp.

Clinical and Epidemiological Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Infections in a Tertiary Hospital in China

Purpose: Infections caused by carbapenem-resistant Klebsiella pneumoniae (CR-KP) are an important public health problem. This study aimed to evaluate the clinical characteristics of patients with CR-KP. Methods: A retrospective cohort study was conducted of all patients with CR-KP infection. A total of 615 patients with CR-KP infection were identified and 135 patients who did not meet the eligibility criteria were excluded. Clinical characteristics, antimicrobial regimens, and patient outcomes were analyzed. Results: The overall mortality rate of CR-KP infections was 37.3% and the mortality rate in patients with bloodstream infections was 66.2%. Survival analysis revealed that there were statistically significant differences between patients with bloodstream infections and those with pulmonary and drainage fluid infections. Logistics regression analysis showed that hemopathy, age >60 years, solid tumors, diabetes, septic shock, acute kidney injury, and stroke were independent predictors of 30-day mortality rate. The chi-square test showed that treatment with a combination of carbapenems, tigecycline, and polymyxin B was superior to treatment with carbapenems with polymyxin B, without tigecycline. Conclusions: CR-KP infections, especially bloodstream infections, have a high mortality rate. The outcome is strongly dependent on patients' clinical conditions. Antimicrobial regimens combining carbapenems, tigecycline, and polymyxin B might be a better choice.

Molecular epidemiology, risk factors, and outcomes of carbapenem-resistant Klebsiella pneumoniae infection in a tertiary hospital in eastern China: for a retrospective study conducted over 4 years

Objectives

Carbapenem-resistant Klebsiella pneumoniae (CRKP) have been extensively disseminated worldwide, resulting in increased mortality. We performed a retrospective analysis of the epidemiology and risk factors for the outcome of CRKP infection in a general teaching hospital in China.

Methods

A molecular and clinical study was conducted for 98 CRKP in a tertiary hospital from January 2013 to December 2016. Carbapenemase gene detection, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) were performed. Logistic regression was also used to identify the risk factors associated with 30-day mortality.

Results

The production of KPC carbapenemase was the main resistant mechanism, and KPC carbapenemase increased annually with a significant difference. However, the molecular outcome revealed the dominance and diversity in CRKP with 24 sequence types (STs) and 59 PFGE types (PTs). The ST11 CRKP strains, which showed a significant increasing trend year by year, were documented as predominant in our study. Additionally, the predominant ST11 CRKP corresponding to PT10 and PT15 continued to exhibit their characteristic patterns. Importantly, the newly identified PT09 and PT16 strains, corresponding to the ST11 lineage, were only discovered in 2016. Meanwhile, factors affecting 30-day mortality and ST11 proportionality with CRKP infection were assessed, and ST11, appropriate empirical treatment, and hospital stays were found to be independently associated with 30-day mortality.

Conclusion

The ST11 CRKP strains played a dominant role in the process; however, the homology of these strains was polymorphic, and the advantage clusters were subject to changes through evolution. Furthermore, in addition to appropriate empirical treatment and hospital stays, ST11 CRKP was independently associated with 30-day mortality. To the best of our knowledge, this association was reported for the first time.

Effectiveness of Extended or Continuous vs. Bolus Infusion of Broad-Spectrum Beta-Lactam Antibiotics for Febrile Neutropenia: A Systematic Review and Meta-Analysis

This systematic review aimed to compare extended infusion or continuous infusion with bolus infusion for febrile neutropenia (FN). We included clinical trials comparing extended or continuous infusion with bolus infusion of beta-lactam antibiotics as empirical treatment for FN and evaluated the clinical failure, all-cause mortality, and adverse event rates. Five articles (three randomized controlled trials (RCTs) and two retrospective studies) from 2014 to 2022 were included. Clinical failure was assessed with a risk ratio (RR) (95% coincident interval (CI)) of 0.74 (0.53, 1.05) and odds ratio (OR) (95% CI) of 0.14 (0.02, 1.17) in the 2 RCTs and retrospective studies, respectively. All-cause mortality was assessed with an RR (95% CI) of 1.25 (0.44, 3.54) and OR (95% CI) of 1.00 (0.44, 2.23) in the RCTs and retrospective studies, respectively. Only 1 RCT evaluated adverse events (with an RR (95% CI) of 0.46 (0.13, 1.65)). The quality of evidence was "low" for clinical failure and all-cause mortality in the RCTs. In the retrospective studies, the clinical failure and all-cause mortality evidence qualities were considered "very low" due to the study design. Extended or continuous infusion of beta-lactam antibiotics did not reduce mortality better than bolus infusion but was associated with shorter fever durations and fewer adverse events.

A case of treatment of multidrug-resistant intracranial Klebsiella pneumoniae infection by multichannel colistin sulfate

The management of severe neurologic infections due to multidrug-resistant (MDR) Klebsiella pneumoniae infection remains a challenge. Limited antibiotic treatment regimens make treatment of severe MDR K. pneumoniae infection more difficult. We describe a patient who developed severe meningitis and ventriculitis after craniotomy caused by MDR K. pneumoniae and was effectively treated with the administration of multichannel applications (intravenous, intrathecal and aerosol inhalation) of colistin sulfate. This case provides clinical evidence that the intrathecal, intravenous and aerosol inhalation of colistin sulfate by multichannel application can be a last resort in refractory intracranial infection by MDR K. pneumoniae.

Bloodstream infections due to Carbapenem-Resistant Enterobacteriaceae in hematological patients: assessment of risk factors for mortality and treatment options

PURPOSE

Bloodstream infection (BSI) caused by Carbapenem-Resistant Enterobacteriaceae (CRE) are associated with poor outcomes in hematological patients. The aim of this study was to identify risk factors for mortality and evaluate the value of epidemiological feature of carbapenemases in guiding antimicrobial treatment options.

METHODS

Hematological patients with monomicrobial CRE BSI between January 2012 and April 2021 were included. The primary outcome was all-cause mortality 30 days after BSI onset.

RESULTS

A total of 94 patients were documented in the study period. Escherichia coli was the most common Enterobacteriaceae, followed by Klebsiella pneumoniae. 66 CRE strains were tested for carbapenemase genes, and 81.8% (54/66) were positive, including NDM (36/54), KPC (16/54), IMP (1/54). Besides, one E. coli isolate was found to express both NDM and OXA-48-like genes. Overall, 28 patients received an antimicrobial treatment containing ceftazidime-avibactam (CAZ-AVI), of which 21 cases were combined with aztreonam. The remaining 66 patients were treated with other active antibiotics (OAAs). The 30-day mortality rate was 28.7% (27/94) for all patients, and was only 7.1% ((2/28) for patients treated with CAZ-AVI. In multivariate analysis, the presence of septic shock at BSI onset (OR 10.526, 95% CI 1.376-76.923) and pulmonary infection (OR 6.289, 95% CI 1.351-29.412) were independently risk factors for 30-day mortality. Comparing different antimicrobial regimens, CAZ-AVI showed a significant survive benefit than OAAs (OR 0.068, 95% CI 0.007-0.651).

CONCLUSION

CAZ-AVI-containing regimen is superior to OAAs for CRE BSI. As the predominance of blaNDM in our center, we recommend the combination with aztreonam when choose CAZ-AVI.

[Therapy-relevant antibiotic resistances in a One Health context]

One Health refers to a concept that links human, animal, and environmental health. In Germany, there is extensive data on antibiotic resistance (AMR) and multidrug-resistant (micro)organisms (MDRO) in human and veterinary medicine, as well as from studies in various environmental compartments (soil, water, wastewater). All these activities are conducted according to different specifications and standards, which makes it difficult to compare data. A focus on AMR and MDRO of human therapeutic importance is helpful to provide some guidance. Most data are available across sectors on methicillin-resistant Staphylococcus aureus (MRSA) and multiresistant Enterobacterales such as Escherichia coli and Klebsiella pneumoniae. Here, the trends of resistance are heterogeneous. Antibiotic use leads to MRE selection, which is well documented. Success in minimizing antibiotic use has also been demonstrated in recent years in several sectors and could be correlated with success in containing AMR and MDRO (e.g., decrease in MRSA in human medicine). Sector-specific measures to reduce the burden of MDRO and AMR are also necessary, as not all resistance problems are linked to other sectors. Carbapenem resistance is still rare, but most apparent in human pathogens. Colistin resistance occurs in different sectors but shows different mechanisms in each. Resistance to antibiotics of last resort such as linezolid is rare in Germany, but shows a specific One Health correlation. Efforts to harmonize methods, for example in the field of antimicrobial susceptibility testing and genome-based pathogen and AMR surveillance, are an important first step towards a better comparability of the different data collections.

Aminoglycosides for the Treatment of Severe Infection Due to Resistant Gram-Negative Pathogens

Aminoglycosides are a family of rapidly bactericidal antibiotics that often remain active against resistant Gram-negative bacterial infections. Over the past decade, their use in critically ill patients has been refined; however, due to their renal and cochleovestibular toxicity, their indications in the treatment of sepsis and septic shock have been gradually reduced. This article reviews the spectrum of activity, mode of action, and methods for optimizing the efficacy of aminoglycosides. We discuss the current indications for aminoglycosides, with an emphasis on multidrug-resistant Gram-negative bacteria, such as extended-spectrum β-lactamase-producing Enterobacterales, carbapenemase-producing Enterobacterales, multidrug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii. Additionally, we review the evidence for the use of nebulized aminoglycosides.

Antibiotic stewardship in the ICU: time to shift into overdrive

Antibiotic resistance is a major health problem and will be probably one of the leading causes of deaths in the coming years. One of the most effective ways to fight against resistance is to decrease antibiotic consumption. Intensive care units (ICUs) are places where antibiotics are widely prescribed, and where multidrug-resistant pathogens are frequently encountered. However, ICU physicians may have opportunities to decrease antibiotics consumption and to apply antimicrobial stewardship programs. The main measures that may be implemented include refraining from immediate prescription of antibiotics when infection is suspected (except in patients with shock, where immediate administration of antibiotics is essential); limiting empiric broad-spectrum antibiotics (including anti-MRSA antibiotics) in patients without risk factors for multidrug-resistant pathogens; switching to monotherapy instead of combination therapy and narrowing spectrum when culture and susceptibility tests results are available; limiting the use of carbapenems to extended-spectrum beta-lactamase-producing Enterobacteriaceae, and new beta-lactams to difficult-to-treat pathogen (when these news beta-lactams are the only available option); and shortening the duration of antimicrobial treatment, the use of procalcitonin being one tool to attain this goal. Antimicrobial stewardship programs should combine these measures rather than applying a single one. ICUs and ICU physicians should be at the frontline for developing antimicrobial stewardship programs.

Treatment options for infections caused by multidrug-resistant Gram-negative bacteria: a guide to good clinical practice

The rapid emergence of multidrug-resistant Gram-negative bacterial infections necessitates the development of new treatments or the repurposing of available antibiotics. Here, treatment options for treatment of these infections, recent guidelines and evidence are reviewed. Studies that included treatment options for infections caused by multidrug-resistant Gram-negative bacteria (Enterobacterales and nonfermenters), as well as extended-spectrum β-lactamase-producing and carbapenem-resistant bacteria, were considered. Potential agents for the treatment of these infections, considering type of microorganism, mechanism of resistant, source and severity of infection as well as pharmacotherapy considerations, are summarized.

Clinical and Genomic Evolution of Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections over Two Time Periods at a Tertiary Care Hospital in South India: A Prospective Cohort Study

INTRODUCTION

The objective of this study was to examine the evolution of carbapenem-resistant Klebsiella pneumoniae (CRKp) infections and their impact at a tertiary care hospital in South India.

METHODS

A comparative analysis of clinical data from two prospective cohorts of patients with CRKp bacteremia (C1, 2014-2015; C2, 2021-2022) was carried out. Antimicrobial susceptibilities and whole genome sequencing (WGS) data of selected isolates were also analyzed.

RESULTS

A total of 181 patients were enrolled in the study, 56 from C1 and 125 from C2. CRKp bacteremia shifted from critically ill patients with neutropenia to others (ICU stay: C1, 73%; C2, 54%; p = 0.02). The overall mortality rate was 50% and the introduction of ceftazidime-avibactam did not change mortality significantly (54% versus 48%; p = 0.49). Oxacillinases (OXA) 232 and 181 were the most common mechanisms of resistance. WGS showed the introduction of New Delhi metallo-β-lactamase-5 (NDM-5), higher genetic diversity, accessory genome content, and plasmid burden, as well as increased convergence of hypervirulence and carbapenem resistance in C2.

CONCLUSIONS

CRKp continues to pose a significant clinical threat, despite the introduction of new antibiotics. The study highlights the evolution of resistance and virulence in this pathogen and the impact on patient outcomes in South India, providing valuable information for clinicians and researchers.

Risk Factors for Infection With Multidrug-Resistant Gram-Negative Bacteria in a Tertiary Care Hospital in Saudi Arabia: A Case-Control Study

Background The increase in the incidence of multidrug-resistant (MDR) organisms especially Gram-negative bacteria (GNB) in healthcare facilities is a serious cause of concern. This study identified risk factors for the infection with these MDR GNB, such as Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli to inform healthcare workers about strategies for their containment. Methods A case-control study was carried out at a tertiary care hospital where 100 patients with healthcare-associated infections (infections arising 48 hours after admission) caused by MDR GNB were compared with two control groups, i.e., 100 patients with healthcare-associated infections caused by non-MDR GNB (not meeting the criteria of MDR) and 100 patients without infection caused by GNB. MDR bacteria were defined as the ones that were non-susceptible to at least one antibiotic in three or more classes of antibiotics. The data were analyzed using descriptive statistics (frequency and percentage of categorical variables). Multivariate regression analysis was undertaken to identify significant predictors of MDR GNB. Odds ratios with 95% confidence intervals were calculated, and the level of significance was determined at p-value < 0.05. Results A total of 388 organisms were isolated during four months (January-April 2015) from 332 patients. Fifty-six (17%) of the patients were infected with more than one organism. Among the MDR bacteria, the most dominant MDR organism was A. baumannii (38%), followed by K. pneumoniae (31%), P. aeruginosa (20%), and E. coli (11%). Among the non-MDR organisms, the most dominant was P. aeruginosa (47%), followed by E. coli (32%), K. pneumoniae (18%), and A. baumannii (3%). Patients with MDR organisms compared with the first control group (patients with non-MDR organisms) showed that prior antibiotic use (p-value: 0.001), intensive care unit (ICU) admission (p-value: 0.001), and indwelling medical devices (p-value: 0.005) were significant risk factors for MDR infections. It was also found that the risk factors for MDR GNB infection were the same in the second control group (patients without infection): prior antibiotic use (p-value: 0.002), ICU admission (p-value: 0.001), and indwelling medical devices (p-value: 0.03). Based on the comparison of the two control groups, prolonged hospital stays of more than five days (p-value: 0.001), immunosuppressive therapy (p-value: 0.02), and over 60 years of age (p-value: 0.02) were significant risk factors for non-MDR infection. Conclusion  The risk factors identified in our study provide guidance to healthcare workers for the prevention and containment of MDR GNB.

Risk factors for infections caused by carbapenem-resistant Enterobacterales: an international matched case-control-control study (EURECA)

BACKGROUND

Data on risk factors for carbapenem-resistant Enterobacterales (CRE) with wider applicability are needed to inform preventive measures and efficient design of randomised trials.

METHODS

An international matched case-control-control study was performed in 50 hospitals with high CRE incidence from March 2016 to November 2018 to investigate different aspects of infections caused by CRE (NCT02709408). Cases were patients with complicated urinary tract infection (cUTI), complicated intraabdominal (cIAI), pneumonia or bacteraemia from other sources (BSI-OS) due to CRE; control groups were patients with infection caused by carbapenem-susceptible Enterobacterales (CSE), and by non-infected patients, respectively. Matching criteria included type of infection for CSE group, ward and duration of hospital admission. Conditional logistic regression was used to identify risk factors.

FINDINGS

Overall, 235 CRE case patients, 235 CSE controls and 705 non-infected controls were included. The CRE infections were cUTI (133, 56.7%), pneumonia (44, 18.7%), cIAI and BSI-OS (29, 12.3% each). Carbapenemase genes were found in 228 isolates: OXA-48/like, 112 (47.6%), KPC, 84 (35.7%), and metallo-β-lactamases, 44 (18.7%); 13 produced two. The risk factors for CRE infection in both type of controls were (adjusted OR for CSE controls; 95% CI; p value) previous colonisation/infection by CRE (6.94; 2.74-15.53; <0.001), urinary catheter (1.78; 1.03-3.07; 0.038) and exposure to broad spectrum antibiotics, as categorical (2.20; 1.25-3.88; 0.006) and time-dependent (1.04 per day; 1.00-1.07; 0.014); chronic renal failure (2.81; 1.40-5.64; 0.004) and admission from home (0.44; 0.23-0.85; 0.014) were significant only for CSE controls. Subgroup analyses provided similar results.

INTERPRETATION

The main risk factors for CRE infections in hospitals with high incidence included previous colonization, urinary catheter and exposure to broad spectrum antibiotics.

FUNDING

The study was funded by the Innovative Medicines Initiative Joint Undertaking (https://www.imi.europa.eu/) under Grant Agreement No. 115620 (COMBACTE-CARE).

Klebsiella pneumoniae: an update on antibiotic resistance mechanisms

Klebsiella pneumoniae colonizes mucosal surfaces of healthy humans and is responsible for one third of all Gram-negative infections in hospitalized patients. K. pneumoniae is compatible with acquiring antibiotic resistance elements such as plasmids and transposons encoding various β-lactamases and efflux pumps. Mutations in different proteins such as β-lactamases, efflux proteins, outer membrane proteins, gene replication enzymes, protein synthesis complexes and transcription enzymes also generate resistance to antibiotics. Biofilm formation is another strategy that facilitates antibiotic resistance. Resistant strains can be treated by combination therapy using available antibiotics, though proper management of antibiotic consumption in hospitals is important to reduce the emergence and proliferation of resistance to current antibiotics.

Clinical characteristics and treatment of IMP-type carbapenemase-producing Enterobacteriaceae bacteremia: Case series and literature review

BACKGROUND

Several carbapenemases have been identified globally in Enterobacteriaceae. In Japan, IMP-type carbapenemase is the most prevalent, although cases of carbapenemase-producing Enterobacteriaceae (CPE) bacteremia are still scarce. The present case series and literature review aimed to elucidate the clinical characteristics and treatment strategies for IMP-type CPE bacteremia.

METHODS

Clinical data on pediatric cases of IMP-type CPE bacteremia at the Tokyo Metropolitan Children's Medical Center between 2010 and 2020 were collected, and a review of past studies of IMP-type CPE bacteremia has been provided.

RESULTS

Five pediatric episodes of IMP-type CPE bacteremia were identified. Our review of previous literature on IMP-type CPE bacteremia revealed 24 adult patients, but no pediatric patients. All 29 cases had underlying diseases, and 23 (79%) received combination therapy. The median duration of antibiotic therapy was 14 days (interquartile range: 9-14 days). The overall mortality rate was 38% (11/29). The mortality rates associated with monotherapy and combination therapy were 67% (4/6) and 30% (7/23), respectively.

CONCLUSIONS

We report the first case series of IMP-type CPE bacteremia in children. Our review of past studies suggests that combination therapy might lead to better survival outcomes in patients with IMP-type CPE bacteremia. Further research is needed to establish an optimal treatment strategy for IMP-type CPE bacteremia.

A subunit vaccine against pneumonia: targeting Streptococcus pneumoniae and Klebsiella pneumoniae

Community-acquired pneumonia is primarily caused by Streptococcus pneumoniae and Klebsiella pneumoniae, two pathogens that have high morbidity and mortality rates. This is largely due to bacterial resistance development against current antibiotics and the lack of effective vaccines. The objective of this work was to develop an immunogenic multi-epitope subunit vaccine capable of eliciting a robust immune response against S. pneumoniae and K. pneumoniae. The targeted proteins were the pneumococcal surface proteins (PspA and PspC) and choline-binding protein (CbpA) of S. pneumoniae and the outer membrane proteins (OmpA and OmpW) of K. pneumoniae. Different computational approaches and various immune filters were employed for designing a vaccine. The immunogenicity and safety of the vaccine were evaluated by utilizing many physicochemical and antigenic profiles. To improve structural stability, disulfide engineering was applied to a portion of the vaccine structure with high mobility. Molecular docking was performed to examine the binding affinities and biological interactions at the atomic level between the vaccine and Toll-like receptors (TLR2 and 4). Further, the dynamic stabilities of the vaccine and TLRs complexes were investigated by molecular dynamics simulations. While the immune response induction capability of the vaccine was assessed by the immune simulation study. Vaccine translation and expression efficiency was determined through an in silico cloning experiment utilizing the pET28a(+) plasmid vector. The obtained results revealed that the designed vaccine is structurally stable and able to generate an effective immune response to combat pneumococcal infection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13721-023-00416-3.

New advances in management and treatment of multidrug-resistant Klebsiella pneumoniae

INTRODUCTION

The management of multidrug-resistant (MDR) Klebsiella pneumoniae (KP) represents a major challenge in the field of infectious diseases. It is associated with a high rate of nosocomial infections with a mortality rate that reaches approximately 50%, even when using an effective antimicrobial therapy. Therefore, combined actions addressing infection control and antibiotic stewardship are required to delay the emergence of resistance. Since new antimicrobial agents targeting MDR-GNB bacteria have been produced during the last years and are now available for physicians to treat MDR, it is fundamental to choose appropriate antimicrobial therapy for K. pneumoniae infection.

AREAS COVERED

The PubMed database was searched to review the most significant recent literature on the topic, including data from articles coming from endemic areas and from the current European and American Guidelines.

EXPERT OPINION

We explore the most effective strategies for prevention of MDR-KP spread and the currently available treatment options, focusing on comparing old strategies and new compounds. We reviewed data concerning newly developed drugs that could play an important role in the future; we also propose a treatment algorithm that could be useful for physicians in daily clinical practice.

Mortality rate and factors associated with mortality of carbapenem-resistant Enterobacteriaceae infection

Background:

Carbapenem-resistant Enterobacteriaceae (CRE) is a serious pathogen with high mortality. Recognition of factors associated with mortality and treating these modifiable factors are crucial to reducing mortality.

Objective:

To determine the 30-day mortality and factors associated with a 30-day mortality of CRE infection.

Methods:

A retrospective cohort study was conducted between January 1, 2015, and December 31, 2019. All patients diagnosed with CRE infection aged ≥18 years were included. Multivariate logistic regression was used for evaluating the factors associated with 30-day mortality and presented as adjusted odds ratio (aOR) with 95% confidence interval (CI).

Result:

One hundred and ninety-four patients were enrolled. The 30-day mortality occurred in 75 patients (38.7%). The common antibiotic regimen was monotherapy and combination of carbapenem, colistin, amikacin, tigecycline, and fosfomycin. CRE isolates were susceptible to tigecycline (93.8%), colistin (91.8%), fosfomycin (89.2%), and amikacin (89.2%). The independent factors associated with 30-day mortality were an increasing simplified acute physiology (SAP) II score (aOR 1.11, 95% CI 1.05-1.16, p < 0.001), sepsis at time of CRE infection diagnosis (aOR 7.93, 95% CI 2.21-28.51, p = 0.002), pneumonia (aOR 4.48, 95% CI 1.61-12.44, p = 0.004), monotherapy (aOR 4.69, 95% CI 1.71-12.85, p = 0.003), and improper empiric antibiotic (aOR 5.13, 95% CI 1.83-14.40, p = 0.002).

Conclusion:

The overall 30-day mortality of CRE infection was high. The factors associated with mortality were an increasing SAP II score, sepsis at time of CRE infection diagnosis, pneumonia, monotherapy, and improper empiric antibiotic. The study suggested that proper empiric antibiotic and combination antibiotics might reduce mortality from CRE infection.

Ceftazidime/Avibactam, Polymyxin or Tigecycline as a Rescue Strategy for the Treatment of Carbapenem-Resistant Klebsiella pneumoniae in Bloodstream Infection: A Retrospective Cohort Study

Objective

To analyze the clinical characteristics, outcomes, and risk factors of patients treated with ceftazidime/avibactam, polymyxin, or tigecycline (CPT) compared with those receiving a conventional therapy (CT) (ie, imipenem, levofloxacin, or gentamicin).

Methods

A single-center retrospective cohort study included patients with carbapenem-resistant Klebsiella pneumoniae bloodstream infection (CRKP-BSI) treated at one Chinese tertiary hospital between March 2012 and November 2022 was performed. Clinical characteristics, outcomes, and risk factors of patients treated with CPT or CT were compared. Predictors of 30-day mortality of patients with CRKP-BSI were also analysed in our study.

Results

Among 184 recruited patients with CRKP-BSI, 39.7% (73/184) were treated with CPT, while 60.3% (111/184) were treated with CT. Compared to patients treated with CT, patients treated with CPT had worse conditions, as evidenced by a higher rate of underlying diseases and invasive procedures; however, they also had a better prognosis and lower rates of 14-day treatment failure (p = 0.024). In addition, univariate analysis and multivariate analysis showed that SOFA score [odds ratio (OR) = 1.310, 95% confidence interval (CI) 1.157-1.483; p < 0.001] and cold weather (OR = 3.658, 95% CI 1.474-9.081; p = 0.005) were independent risk factors for 30-day mortality.

Conclusion

Compared to CRKP-BSI patients treated with CT, patients treated with CPT had worse conditions but better prognoses. CRKP-BSI occurred more frequently in hot weather; however, higher 30-day mortality was associated with cold weather. A randomized trial is needed to confirm these observational results.

High Frequency of blaOXA-48like Producing Klebsiella pneumoniae Isolated from Nosocomial Infection in Azerbaijan, Iran

BACKGROUND

Klebsiella pneumoniae is one of the significant agents of hospital-acquired infections. In recent years, carbapenem-resistant K. pneumoniae (CRKP) isolates have been found in numerous epidemics of nosocomial infections. This study aimed to determine carbapenem resistance mechanisms and molecular epidemiological of CRKP infections in Azerbaijan, Iran.

MATERIALS AND METHODS

A total of 50 non-duplicated CRKP from January 2020 to December 2020 were isolated form Sina and Imam Reza Hospitals in Tabriz, Iran. Antimicrobial susceptibility testing was performed by the disk-diffusion method. The carbapenem resistance mechanisms were determined by the phenotypic and PCR procedures. CRKP isolates were typed by the Random Amplified Polymorphic DNA PCR (RAPD-PCR) technique.

RESULTS

Amikacin was the most effective antibiotics against CRKP isolates. AmpC overproduction was observed in five CRKP isolates. Efflux pump activity was found in one isolate by the phenotypic method. Carba NP test could find carbapenemases genes in 96% of isolates. The most common carbapenemases gene in CRKP isolates were bla_OXA-48-like (76%) followed by bla_NDM (50%), bla_IMP (22%), bla_VIM (10%), and bla_KPC (10%). The outer membrane protein genes (OmpK36 and OmpK35) were identified in 76% and 82% of CRKP isolates, respectively. RAPD-PCR analysis yielded 37 distinct RAPD-types. Most bla_OXA-48-like positive CRKP isolates were obtained from patients hospitalized in intensive care unit (ICU) wards with urinary tract infections.

CONCLUSION

The bla_OXA-48-like is the main carbapenemase among CRKP isolates in this area. Most bla_OXA-48-like producer CRKP strains were collected from the ICU ward and urine samples. To control infections due to CRKP, a strict control program in hospital settings is required.

Ten Years of KPC-Kp Bloodstream Infections Experience: Impact of Early Appropriate Empirical Therapy on Mortality

Background. In K. pneumoniae KPC (KPC-Kp) bloodstream infections (BSI), INCREMENT CPE score >7, Charlson Comorbidity Index (CCI) ≥3 and septic shock are recognized predictors of mortality, with a possible beneficial effect of combination therapy in seriously ill patients. Materials and Methods. We conducted a ten-year retrospective study including all KPC-Kp BSI in patients ≥18 years of age with the aim to evaluate the characteristics and impact of appropriate empirical therapy, either monotherapy or combination therapy, and targeted therapy on mortality. Appropriate therapy was defined as at least one active antimicrobial agent with in vitro activity against KPC-kp demonstrated by susceptibility testing, administered within 48 h from blood culture collection. Results. The median age of the 435 analyzed patients was 66.09 years (IQR 54.87−73.98). The median CCI was 4. KPC-Kp colonization was present in 324 patients (74.48%). The probable origin of the KPC-Kp BSI was not identified in 136 patients (31.26%), whereas in 120 (27.59%) patients, it was CVC-related, and in 118 (27.13%), it was respiratory. Source control was achieved in 87 patients (72.5%) with CVC-related KPC-Kp BSI. The twenty-eight-day survival was 70.45% for empirical monotherapy, 63.88% for empirical combination therapy and 57.05% for targeted therapy (p = 0.0399). A probable source of KPC-Kp BSI other than urinary, CVC or abdominal [aHR 1.64 (IC 1.15−2.34) p = 0.006] and deferred targeted therapy [HR 1.67 (IC 1.12−2.51), p= 0.013] emerged as predictors of mortality, whereas source control [HR 0.62 (IC 0.44−0.86), p = 0.005] and ceftazidime/avibactam administration in empirical therapy [aHR 0.37 (IC 0.20−0.68) p = 0.002] appeared as protective factors. Discussion. These data underline the importance of source control together with timing appropriateness in the early start of empirical therapy over the choice of monotherapy or combination therapy and the use of ceftazidime/avibactam against KPC-Kp BSI.

Antimicrobial treatment of monomicrobial phenotypic carbapenem-resistant Klebsiella pneumoniae bacteremia: Two are better than one

BACKGROUNDS

Infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) are emerging worldwide. The optimal treatment for CRKP infections is challenging for clinicians because therapeutic agents are greatly limited.

MATERIAL AND METHODS

A retrospective study of CRKP monomicrobial bacteremia was conducted at a medical center between 2010 and 2016. The use of at least one or more drugs with in vitro activity against the blood isolates was defined as appropriate combination therapy. The logistic regression model and propensity score analysis was used to assess clinical effects of therapeutic strategies. The 30-day crude mortality was the primary end point.

RESULTS

Two hundred and three patients were eligible and the 30-day mortality rate was 37.9% (77 patients). As compared with monotherapy, empirical (11.6 vs. 57.3%, p < .001) or definitive (26.5% vs. 48.6%, p = .001) combination antibiotic therapy showed a lower 30-day mortality rate independently. The propensity score analysis showed that those receiving combination therapy had less clinical (p ≤ .001) or microbiological failure (p = .003) and a lower 30-day mortality rate (p < .001). Among various regimens of definitive therapy, the 30-day mortality rate was the lowest among patients with appropriate combination therapy 23.6%, (p < .001; by log rank test). The primary outcome was similar in those with definitive carbapenem-containing and carbapenem-sparing combination regimens (p = .81). The presence or absence of carbapenemase production did not affect the mortality rate (p = .26).

CONCLUSION

Combination therapy, regardless of carbapenem-containing or carbapenem-sparing regimens, was associated with a favorable outcome.

Active surveillance of carbapenem-resistant gram-negative bacteria to guide antibiotic therapy: a single-center prospective observational study

Background

Carbapenem-resistant gram-negative bacteria (CRGNB) have become a public health concern worldwide. The risk factors associated with CRGNB infection after colonization are unknown, nor is the optimal timing of antibiotic treatment, warranting further investigation.

Methods

A 4-year single-center prospective observational study was conducted. CRGNB-colonized patients were incorporated on admission into our observation cohort for an active surveillance culture program, and analysis of risk factors associated with infections after CRGNB colonization was performed. We divided patients into empirical antibiotic therapy groups and standard antibiotic therapy groups according to whether antibiotics were used before or after cultures yielded a result to explore the relationship between the timing of antibiotics and clinical efficacy.

Results

152 out of 451 CRGNB-colonized patients in the prospective observational cohort developed CRGNB infection. The risk factors associated with CRGNB infection after colonization included CRKP (P < 0.001, OR = 3.27) and CRPA (P < 0.001, OR = 2.97) colonization, history of carbapenems use (P < 0.001, OR = 5.48), and immunocompromise (P < 0.001, OR = 7.07). There were 88 infected patients in the empirical antibiotic therapy groups and 64 in standard antibiotic therapy groups. The mortality was lower in empirical therapy groups than standard therapy groups (17.0% vs. 37.5%, P = 0.004, OR = 0.32).

Conclusions

CRGNB colonized patients who are prone to infection have some high-risk factors included CRKP and CRPA colonization, immunocompromise, and prior carbapenems use. Once infection occurs in CRGNB-colonized patients, early use of effective antibiotics may be associated with reduced mortality, but more studies are needed.

Empirical antibiotic therapy for difficult-to-treat Gram-negative infections: when, how, and how long?

PURPOSE OF REVIEW

To discuss empirical therapy for severe infections due to Gram-negative bacteria with difficult-to-treat resistance (GNB-DTR) in current clinical practice, focusing in particular on the positioning of novel therapeutic agents and rapid diagnostic tests.

RECENT FINDINGS

The current era of novel agents active against GNB-DTR and showing differential activity against specific determinants of resistance is an unprecedented scenario, in which the clinical reasoning leading to the choice of the empirical therapy for treating severe GNB-DTR infections is becoming more complex, but it also allows for enhanced treatment precision.

SUMMARY

Novel agents should be used in line with antimicrobial stewardship principles, aimed at reducing selective pressure for antimicrobial resistance. However, this does not mean that they should not be used. Indeed, excesses in restrictive uses may be unethical by precluding access to the most effective and less toxic treatments for patients with severe GNB-DTR infections. Given these premises (the 'how'), empirical treatment with novel agents should be considered in all patients with risk factors for GNB-DTR and severe clinical presentation of acute infection (the 'when'). Furthermore, empirical novel agents should preferably be continued only for a few hours, until de-escalation, modification, or confirmation (as targeted therapy) is made possible by the results of rapid diagnostic tests (the 'how long').

Mortality-Related Risk Factors and Novel Antimicrobial Regimens for Carbapenem-Resistant Enterobacteriaceae Infections: A Systematic Review

OBJECTIVE

Carbapenem-resistant Enterobacteriaceae (CRE) has become a significant public health problem in the last decade. We aimed to explore the risk factors of mortality in patients with CRE infections and to focus on the current evidence on antimicrobial regimens for CRE infections, particularly from the perspective of mortality.

METHODS

A systematic literature review was performed by searching the databases of EMBASE, PubMed, and the Cochrane Library to identify studies that evaluated mortality-related risk factors and antimicrobial regimens for CRE infections published from 2012 to 2022.

RESULTS

In total, 33 and 28 studies were included to analyze risk factors and antibiotic treatment, respectively. The risk factors most frequently reported as significantly associated with CRE mortality were antibiotic use (92.9%; 26/28 studies), comorbidities (88.7%; 23/26 studies), and hospital-related factors (82.8%; 24/29 studies). In 10 studies that did not contain ceftazidime/avibactam (CAZ-AVI) therapy, seven demonstrated significantly lower mortality in combination therapy than in monotherapy. However, 5 of 6 studies identified no substantial difference between CAZ-AVI monotherapy and CAZ-AVI combination therapy. Six studies reported substantially lower mortality in CAZ-AVI regimens than in other regimens.

CONCLUSION

Several risk factors, particularly antibiotic use and patients' comorbidities, are strong risk factors for CRE mortality. The optimal regimen for CRE infections remains controversial. Combination therapy should be considered when carbapenems, colistin, tigecycline, or aminoglycosides are administered. CAZ-AVI appears to be a promising antibiotic for CRE infections. Most importantly, treatment should be individualized according to the source and severity of the disease or other highly related risk factors.

Carbapenem-Resistant Gram-Negative Fermenting and Non-Fermenting Rods Isolated from Hospital Patients in Poland-What Are They Susceptible to?

Gram-negative fermenting and non-fermenting bacteria are important etiological factors of nosocomial and community infections, especially those that produce carbapenemases. Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa are the most frequently-detected carbapenemase-producing microorganisms. The predominant type of resistance is metallo-β-lactamase (MBL). These bacteria are predominantly isolated from bronchial alveolar lavage, urine, and blood. Carbapenemase-producing Enterobacterales (CPE) strains are always multi-drug-resistant. This significantly limits the treatment options for this type of infection, extends the time of patient hospitalization, and increases the risk of a more severe and complicated disease course. Preventing the transmission of these microorganisms should be a major public health initiative. New antibiotics and treatment regimens offer hope against these infections.

Treatment strategies for OXA-48-like and NDM producing Klebsiella pneumoniae infections

INTRODUCTION

OXA-48 and NDM are amongst the most prevalent carbapenemase types associated with Klebsiella pneumoniae worldwide, with an increase in their prevalence in recent years. Knowledge on the treatment of carbapenem-resistant Klebsiella pneumoniae (CRKP) comes from KPC-producing CRKP with limited data available for OXA-48-like and NDM producers. Our aim is to review the literature on the treatment of OXA-48-like and NDM-producing CRKP with the goal of providing an update on the available antibiotic treatment strategies, particularly in light of changing carbapenemase epidemiology and increasing antimicrobial resistance.

AREAS COVERED

We reviewed studies looking at the antibiotic treatment and outcome of OXA-48-like and/or NDM-producing CRKP.

EXPERT OPINION

The best available treatment option for OXA-48 producers is ceftazidime-avibactam, where available and when the price permits its use. Colistin remains as the second-line option if in vitro susceptibility is demonstrated with an appropriate method. There is not enough evidence to support the use of meropenem-containing combination therapies for meropenem-resistant OXA-48 producers. Treatment of NDM producers is an unmet need. Ceftazidime-avibactam and aztreonam combination or cefiderocol can be used for NDM producers, where available. Higher cefiderocol MICs against NDM producers is concerning. Aztreonam-avibactam provides hope for the treatment of NDM producers.

Carbapenem-Resistant Klebsiella pneumoniae: Diversity, Virulence, and Antimicrobial Resistance

Background

Klebsiella pneumoniae (K. pneumoniae) is one of the most important pathogens in nosocomial infections. It has resistance to most antibiotics, even carbapenem, resulting in restricted therapeutic options.

Purpose

We tried to assess the antimicrobial resistance and virulence fitness of carbapenem-resistant K. pneumoniae (CRKP) in addition to their phenotypic and genotypic diversity.

Materials and Methods

The conventional methods, automated Vitek-32 system, and antimicrobial susceptibility pattern were used to detect CRKP isolates. Virulence and resistance genes profiles were created by using PCR technique. The correlation analysis was done by using R-program.

Results

The antimicrobial resistance profile for all our K. pneumoniae isolates was shocking as the MDR and CRKP were the most prominent phenotypes. Unfortunately, high degrees of heterogeneity among our CRKP isolates were recorded, as 97.5% of them were differentiated into different clusters. We found a negative correlation between the existence of virulence and antimicrobial resistance genes. In contrast to sputum and urine CRPK isolates, the blood isolates showed high antimicrobial resistance and low virulence fitness. Finally, K. pneumoniae creates several outbreaks and crises in Egypt owing to the highly heterogeneity and the wide spread of multidrug-resistant (MDR) and multi-virulent CRKP phenotypes.

Conclusion

Our results are significant and alarming to health organizations throughout the world for the severity and heterogeneity of K. pneumoniae infections. Therefore, the traditional method for treatment of CRKP infections must be renewed. Additionally, the treatment protocols must be well correlated with the site of infections, phenotypes, and genotypes of CRKP strains.

Cost-effectiveness of strategies to control the spread of carbapenemase-producing Enterobacterales in hospitals: a modelling study

Background

Spread of resistant bacteria causes severe morbidity and mortality. Stringent control measures can be expensive and disrupt hospital organization. In the present study, we assessed the effectiveness and cost-effectiveness of control strategies to prevent the spread of Carbapenemase-producing Enterobacterales (CPE) in a general hospital ward (GW).

Methods

A dynamic, stochastic model simulated the transmission of CPE by the hands of healthcare workers (HCWs) and the environment in a hypothetical 25-bed GW. Input parameters were based on published data; we assumed the prevalence at admission of 0.1%. 12 strategies were compared to the baseline (no control) and combined different prevention and control interventions: targeted or universal screening at admission (TS or US), contact precautions (CP), isolation in a single room, dedicated nursing staff (DNS) for carriers and weekly screening of contact patients (WSC). Time horizon was one year. Outcomes were the number of CPE acquisitions, costs, and incremental cost-effectiveness ratios (ICER). A hospital perspective was adopted to estimate costs, which included laboratory costs, single room, contact precautions, staff time, i.e. infection control nurse and/or dedicated nursing staff, and lost bed-days due to prolonged hospital stay of identified carriers. The model was calibrated on actual datasets. Sensitivity analyses were performed.

Results

The baseline scenario resulted in 0.93 CPE acquisitions/1000 admissions and costs 32,050 €/1000 admissions. All control strategies increased costs and improved the outcome. The efficiency frontier was represented by: (1) TS with DNS at a 17,407 €/avoided CPE case, (2) TS + DNS + WSC at a 30,700 €/avoided CPE case and (3) US + DNS + WSC at 181,472 €/avoided CPE case. Other strategies were dominated. Sensitivity analyses showed that TS + CP might be cost-effective if CPE carriers are identified upon admission or if the cases have a short hospital stay. However, CP were effective only when high level of compliance with hand hygiene was obtained.

Conclusions

Targeted screening at admission combined with DNS for identified CPE carriers with or without weekly screening were the most cost-effective options to limit the spread of CPE. These results support current recommendations from several high-income countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01149-0.

Adsorption-desorption and degradation of colistin in soils under aerobic conditions

Colistin has broad-spectrum activity against Gram-negative bacteria and has been considered as the last-resort treatment for multiantibiotic-resistant Gram-negative bacteria infections in human. And it is also world widely utilized as a veterinary medicine for the promotion of growth, prevention and control of diseases in livestock and poultry. Extensive use of colistin in husbandry results in the introduction of large amounts of colistin to the surrounding environment via animals' urine and feces, potentially inducing the prevalence of colistin resistance bacteria and the impact of the ecological environment. The study investigated the adsorption, desorption and degradation of colistin in soils using high sensitivity UPLC-MS/MS assays. An MS based assay was established to directly determine colistin in the soil. It was observed that the moderate adsorption affinity of colistin to the three soils with adsorption strength (1/n) ranging from 0.6897 to 1.3333. Colistin exhibited the highest adsorption affinity to the sandy loam, followed by the sand and loam. Despite of different characteristics of three soils, the adsorption capacity of the three soils was comparable. The adsorption of colistin to the three types of soils analyzed was irreversible. The degradation experiments showed that the degradation of colistin in the sandy loam was relatively slow with a degradation half-life in a range of 13.2-29.7 days when colistin was applied to the sandy loam at a level of 10 ~ 40 µg/g. The degradation of colistin occurred in the mixture of the sandy loam and feces recovered from the colistin treated broiler as well. 25% of colistin remained in the mixture under environmental conditions after 14 days. Composting the sandy loam by directly covering the soil surface with colistin treated broilers' feces resulted in the introduction of colistin to the sandy loam. Colistin was observed in both the topsoil from the contact surface and sandy loam samples collected 20 cm below the contact surface. The understanding of adsorption-desorption behaviors, degradation and mobility of colistin in soils might offer insights into the potential impact of colistin on the emergence and prevalence of resistant bacteria and the ecological environment.

Double-, single- and none-carbapenem-containing regimens for the treatment of carbapenem-resistant Enterobacterales (CRE) bloodstream infections: a retrospective cohort

OBJECTIVES

To investigate the effect of double-, single- and none-carbapenem-containing antimicrobial regimens in the treatment of patients with carbapenem-resistant Enterobacterales (CRE) bloodstream infections (BSIs).

METHODS

We conducted a retrospective cohort study from 2013 to 2020 in two Brazilian hospitals. Patients ≥18 years old with CRE BSI were included and excluded if death or treatment duration for ≤48 h after BSI or non-Class A-producing carbapenemase isolates. We evaluated the impact of different carbapenem-containing regimens on 30 day mortality through a propensity score adjusted model and a Cox proportional hazards model.

RESULTS

Two-hundred and seventy-nine patients were included for analyses: 47 (16.9%), 149 (53.4%) and 83 (29.8%) were treated with double-, single- and none-carbapenem-containing regimens, respectively. One-hundred and seventeen (41.9%) patients died in 30 days. Treatment with a single-carbapenem regimen was associated with a lower risk of death in 30 days compared with therapies containing no carbapenem [adjusted HR (aHR) 0.66, 95% CI 0.44-0.99, P = 0.048], when adjusted for Charlson score and ICU admission at baseline, while double-carbapenem regimens were not associated with a lower risk of death (aHR 0.78, 95% CI 0.46-1.32, P = 0.35). Propensity score adjusted model results went in the same direction.

CONCLUSIONS

Double-carbapenem- was not superior to single-carbapenem-containing regimens in patients with CRE BSIs. Single-carbapenem-containing schemes were associated with a lower mortality risk.

Treatment of MDR Gram-Negative Bacteria Infections: Ongoing and Prospective

Antimicrobial resistance is a serious public health concern across the world. Gram-negative resistance has propagated over the globe via various methods, the most challenging of which include extended-spectrum β-lactamases, carbapenemases, and AmpC enzymes. Gram-negative bacterial infections are difficult to treat in critically extremely sick persons. Resistance to different antibiotic treatments nearly always lowers the probability of proper empirical coverage, sometimes resulting in severe outcomes. Multidrug resistance can be combated with varying degrees of success using a combination of older drugs with high toxicity levels and novel therapeutics. The current therapies for multidrug-resistant Gram-negative bacteria are discussed in this review, which includes innovative medications, older pharmaceuticals, creative combinations of the two, and therapeutic targets.