Bloodstream Infections Caused by Carbapenem-Resistant Enterobacterales: Risk Factors for Mortality, Antimicrobial Therapy and Treatment Outcomes from a Prospective Multicenter Study

Hospital mortality and length of stay associated with Enterobacterales positive blood cultures: a multicenter analysis

Delayed time to antimicrobial susceptibility results can impact patients' outcomes. Our study evaluated the impact of susceptibility turnaround time (TAT) and inadequate empiric antibacterial therapy (IET) in patients with bloodstream infections (BSI) caused by Enterobacterales (ENT) species on in-hospital mortality and length of stay (LOS). This retrospective, multicenter investigation which included 29,570 blood ENT-positive admissions across 161 US healthcare facilities evaluated the association between antimicrobial susceptibility testing (AST) TAT, carbapenem susceptibility, and empiric therapy on post-BSI in-hospital mortality and LOS following an ENT BSI event in adult patients. After adjusting for outcomes covariates, post-BSI in-hospital mortality was significantly higher for patients in the IET vs adequate empiric therapy (AET) group [odds ratio (OR): 1.61 (95% CI: 1.32, 1.98); P < 0.0001], and when AST TAT was >63 h [OR:1.48 (95% CI: 1.16, 1.90); P = 0.0017]. Patients with carbapenem non-susceptible (carb-NS) ENT BSI had significantly higher LOS (16.6 days, 95% CI: 15.6, 17.8) compared to carbapenem susceptible (carb-S, 12.2 days, 95% CI: 11.8, 12.6), (P < 0.0001). Extended AST TAT was significantly associated with longer LOS for TAT of 57-65 h and >65 h (P = 0.005 and P< 0.0001, respectively) compared to TAT ≤42 h (reference). Inadequate empiric therapy (IET), carb-NS, and delayed AST TAT are significantly associated with adverse hospital outcomes in ENT BSI. Workflows that accelerate AST TAT for ENT BSIs and facilitate timely and adequate therapy may reduce post-BSI in-hospital mortality rate and LOS.IMPORTANCEFor patients diagnosed with bloodstream infections (BSI) caused by Enterobacterales (ENT), delayed time to antimicrobial susceptibility (AST) results can significantly impact in-hospital mortality and hospital length of stay. However, this relationship between time elapsed from blood culture collection to AST results has only been assessed, to date, in a limited number of publications. Our study focuses on this important gap using retrospective data from 29,570 blood ENT-positive admissions across 161 healthcare facilities in the US as we believe that a thorough understanding of the dynamic between AST turnaround time, adequacy of empiric therapy, post-BSI event mortality, and hospital length of stay will help guide effective clinical management and optimize outcomes of patients with ENT infections.

Clinical risk factors and outcomes of carbapenem-resistant Escherichia coli nosocomial infections in a Chinese teaching hospital: a retrospective study from 2013 to 2020

The emergence of carbapenem-resistant Escherichia coli strains poses a considerable challenge to global public health, and little is known about carbapenemase-producing E. coli strains in Tianjin, China. This study aimed to investigate the risk factors for infections with carbapenem-resistant E. coli (CREC) strains. This retrospective case-control study was conducted at a tertiary teaching hospital. A total of 134 CREC clinical isolates were collected from the General Hospital of Tianjin Medical University between 2013 and 2020. The control group was selected at a ratio of 1:1 from patients with nosocomial carbapenem-susceptible E. coli infection. Risk factors for nosocomial CREC infection and clinical outcomes were analyzed using univariate and multivariate analyses. Multivariate analysis revealed that cephalosporin exposure (odd ratio OR = 2.01), carbapenem exposure (OR = 1.96), glucocorticoid exposure (OR = 32.45), and surgical history (OR = 3.26) were independent risk factors for CREC infection. The in-hospital mortality rate in the CREC group was 29.1%, and age >65 years (OR = 3.19), carbapenem exposure (OR = 3.54), and central venous catheter insertion (OR = 4.19) were independent risk factors for in-hospital mortality in patients with CREC infections. Several factors were identified in the development of nosocomial CREC infections. The CREC isolates were resistant to most antibiotics. Reducing CREC mortality requires a comprehensive consideration of appropriate antibiotic use, underlying diseases, and invasive procedures.IMPORTANCEEscherichia coli is an opportunistic pathogen that causes severe hospital-acquired infections. The spread of carbapenem-resistant E. coli is a global threat to public health, and only a few antibiotics are effective against these infections. Consequently, these infections are usually associated with poor prognosis and high mortality. Therefore, understanding the risk factors associated with the causes and outcomes of these infections is crucial to reduce their incidence and initiate appropriate therapies. In our study, several factors were found to be involved in nosocomial carbapenem-resistant E. coli (CREC) infections, and CREC isolates were resistant to most antibiotics. Reducing CREC mortality needs a comprehensive consideration of whether antibiotics are used appropriately, underlying diseases, and invasive interventions. These findings provide valuable evidence for the development of anti-infective therapy, infection prevention, and control of CREC-positive infections.

Global evolutionary dynamics of virulence genes in ST11-KL47 carbapenem-resistant Klebsiella pneumoniae

ST11-KL47 is a hypervirulent carbapenem-resistant Klebsiella pneumoniae (CRKP) that is highly prevalent in China and poses a major public health risk. To investigate the evolutionary dynamics of virulence genes in this subclone, we analysed 78 sequenced isolates obtained from a long-term study across 29 centres from 17 cities in China. Virulence genes were located in large hybrid pNDM-Mar-like plasmids (length: ∼266 kilobases) rather than in classical pK2044-like plasmids. These hybrid plasmids, derived from the fusion of pK2044 and pNDM-Mar plasmids mediated by insertion sequence (IS) elements (such as ISKpn28 and IS26), integrated virulence gene fragments into the chromosome. Analysis of 217 sequences containing the special IncFIB (pNDM-Mar) replicon using public databases indicated that these plasmids typically contained T4SS-related and multiple antimicrobial resistance genes, were present in 24 countries, and were found in humans, animals, and the environment. Notably, the chromosomal integration of virulence genes was observed in strains across five countries across two continents. In vivo and in vitro models showed that the large hybrid plasmid increased the host fitness cost while increasing virulence. Conversely, virulence genes transferred to chromosomes resulted in increased fitness and lower virulence. In conclusion, virulence genes in the plasmids of ST11-KL47 CRKP are evolving, driven by adaptive negative selection, to enable vertical chromosomal inheritance along with conferring a survival advantage and low pathogenicity.

Ceftazidime/avibactam versus polymyxin B in carbapenem-resistant Klebsiella pneumoniae infections: a propensity score-matched multicenter real-world study

OBJECTIVES

In this retrospective observational multicenter study, we aimed to assess efficacy and mortality between ceftazidime/avibactam (CAZ/AVI) or polymyxin B (PMB)-based regimens for the treatment of Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections, as well as identify potential risk factors.

METHODS

A total of 276 CRKP-infected patients were enrolled in our study. Binary logistic and Cox regression analysis with a propensity score-matched (PSM) model were performed to identify risk factors for efficacy and mortality.

RESULTS

The patient cohort was divided into PMB-based regimen group (n = 98, 35.5%) and CAZ/AVI-based regimen group (n = 178, 64.5%). Compared to the PMB group, the CAZ/AVI group exhibited significantly higher rates of clinical efficacy (71.3% vs. 56.1%; p = 0.011), microbiological clearance (74.7% vs. 41.4%; p < 0.001), and a lower incidence of acute kidney injury (AKI) (13.5% vs. 33.7%; p < 0.001). Binary logistic regression revealed that the treatment duration independently influenced both clinical efficacy and microbiological clearance. Vasoactive drugs, sepsis/septic shock, APACHE II score, and treatment duration were identified as risk factors associated with 30-day all-cause mortality. The CAZ/AVI-based regimen was an independent factor for good clinical efficacy, microbiological clearance, and lower AKI incidence.

CONCLUSIONS

For patients with CRKP infection, the CAZ/AVI-based regimen was superior to the PMB-based regimen.

Expansion and transmission dynamics of high risk carbapenem-resistant Klebsiella pneumoniae subclones in China: An epidemiological, spatial, genomic analysis

AIMS

Carbapenem-resistant Klebsiella pneumonia (CRKP) is a global threat that varies by region. The global distribution, evolution, and clinical implications of the ST11 CRKP clone remain obscure.

METHODS

We conducted a multicenter molecular epidemiological survey using isolates obtained from 28 provinces and municipalities across China between 2011 and 2021. We integrated sequences from public databases and performed genetic epidemiology analysis of ST11 CRKP.

RESULTS

Among ST11 CRKP, KL64 serotypes exhibited considerable expansion, increasing from 1.54% to 46.08% between 2011 and 2021. Combining our data with public databases, the phylogenetic and phylogeography analyses indicated that ST11 CRKP appeared in the Americas in 1996 and spread worldwide, with key clones progressing from China's southeastern coast to the inland by 2010. Global phylogenetic analysis showed that ST11 KL64 CRKP has evolved to a virulent, resistant clade with notable regional spread. Single-nucleotide polymorphism (SNP) analysis identified BMPPS (bmr3, mltC, pyrB, ppsC, and sdaC) as a key marker for this clade. The BMPPS SNP clade is associated with high mortality and has strong anti-phagocytic and competitive traits in vitro.

CONCLUSIONS

The high-risk ST11 KL64 CRKP subclone showed strong expansion potential and survival advantages, probably owing to genetic factors.

Epidemiology and antimicrobial susceptibility profiles of Enterobacterales causing bloodstream infections before and during COVID-19 pandemic: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART) in Taiwan, 2018-2021

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has contributed to the spread of antimicrobial resistance, including carbapenem-resistant Enterobacterales.

METHODS

This study utilized data from the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program in Taiwan. Enterobacterales from patients with bloodstream infections (BSIs) were collected and subjected to antimicrobial susceptibility testing and β-lactamase gene detection using a multiplex PCR assay. Statistical analysis was conducted to compare susceptibility rates and resistance genes between time periods before (2018-2019) and during the COVID-19 pandemic (2020-2021).

RESULTS

A total of 1231 Enterobacterales isolates were collected, predominantly Escherichia coli (55.6%) and Klebsiella pneumoniae (29.2%). The proportion of nosocomial BSIs increased during the COVID-19 pandemic (55.5% vs. 61.7%, p < 0.05). Overall, susceptibility rates for most antimicrobial agents decreased, with Enterobacterales from nosocomial BSIs showing significantly lower susceptibility rates than those from community-acquired BSIs. Among 123 Enterobacterales isolates that underwent molecular resistance mechanism detection, ESBL, AmpC β-lactamase, and carbapenemase genes were detected in 43.1%, 48.8% and 16.3% of the tested isolates, respectively. The prevalence of carbapenemase genes among carbapenem-resistant Enterobacterales increased during the pandemic, although the difference was not statistically significant. Two novel β-lactamase inhibitor combinations, imipenem-relebactam and meropenem-vaborbactam, preserved good efficacy against Enterobacterales. However, imipenem-relebactam showed lower in vitro activity against imipenem-non-susceptible Enterobacterales than that of meropenem-vaborbactam.

CONCLUSIONS

The COVID-19 pandemic appears to be associated with a general decrease in antimicrobial susceptibility rates among Enterobacterales causing BSIs in Taiwan. Continuous surveillance is crucial to monitor antimicrobial resistance during the pandemic and in the future.

Comparison of bacteremic pneumonia caused by Escherichia coli and Klebsiella pneumoniae: A retrospective study

OBJECTIVES

To compare the prognosis of bacteremic pneumonia caused by Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) pathogens.

METHODS

A retrospective analysis was carried out on the clinical data of 162 patients who were diagnosed with bacterial pneumonia caused by either K. pneumoniae or E. coli between 2016-2019. The primary outcome of the analysis was the patients' 30-day mortality rate.

RESULTS

There were 82 patients in the E. coli bacteremic pneumonia (E. coli-BP) group and 80 patients in the K. pneumoniae bacteremic pneumonia (KP-BP) group. The 30-day mortality rate was 43.75% (n=35/80) in the KP-BP group and 21.95% (n=18/82) in the E. coli-BP group (p<0.001). Following the adjustment for confounding variables in 4 distinct models, the hazard ratios for the primary outcome in KP-BP were determined to be 0.70 (95% confidence interval [CI]: [0.44-1.02]) in Model 1, 0.72 (95% CI: [0.46-1.14]) in Model 2, 0.99 (95% CI: [0.57-1.73]) in Model 3, and 1.22 (95% CI: [0.69-2.18]) in Model 4.

CONCLUSION

Patients diagnosed with KP-BP exhibited a similar prognosis as those diagnosed with E. coli-BP. For patients with KP-BP, the risk of mortality was significantly higher for those who were in the intensive care unit, were infected with carbapenem-resistant strains, or had a high sequential organ failure assessment score. In patients with E. coli-BP, the Pitt bacteremia score was strongly associated with the 30-day mortality rate.

Ceftazidime-avibactam versus polymyxins in treating patients with carbapenem-resistant Enterobacteriaceae infections: a systematic review and meta-analysis

OBJECTIVE

Carbapenem-resistant Enterobacteriaceae (CRE) pose a significant threat to human health and have emerged as a major public health concern. We aimed to compare the efficacy and the safety of ceftazidime-avibactam (CAZ-AVI) and polymyxin in the treatment of CRE infections.

METHODS

A systematic review and meta-analysis was performed by searching the databases of EMBASE, PubMed, and the Cochrane Library. Published studies on the use of CAZ-AVI and polymyxin in the treatment of CRE infections were collected from the inception of the database until March 2023. Two investigators independently screened the literature according to the inclusion and exclusion criteria, evaluated the methodological quality of the included studies and extracted the data. The meta-analysis was performed using RevMan 5.4 software.

RESULTS

Ten articles with 833 patients were included (CAZ-AVI 325 patients vs Polymyxin 508 patients). Compared with the patients who received polymyxin-based therapy, the patients who received CAZ-AVI therapy had significantly lower 30-days mortality (RR = 0.49; 95% CI 0.01-2.34; I2 = 22%; P < 0.00001), higher clinical cure rate (RR = 2.70; 95% CI 1.67-4.38; I2 = 40%; P < 0.00001), and higher microbial clearance rate (RR = 2.70; 95% CI 2.09-3.49; I2 = 0%; P < 0.00001). However, there was no statistically difference in the incidence of acute kidney injury between patients who received CAZ-AVI and polymyxin therapy (RR = 1.38; 95% CI 0.69-2.77; I2 = 22%; P = 0.36). In addition, among patients with CRE bloodstream infection, those who received CAZ-AVI therapy had significantly lower mortality than those who received polymyxin therapy (RR = 0.44; 95% CI 0.27-0.69, I2 = 26%, P < 0.00004).

CONCLUSIONS

Compared to polymyxin, CAZ-AVI demonstrated superior clinical efficacy in the treatment of CRE infections, suggesting that CAZ-AVI may be a superior option for CRE infections.

Identifying Effective Durations of Antibiotic Therapy for the Treatment of Carbapenem-resistant Enterobacterales Bloodstream Infections: A Multicenter Observational Study

In a propensity-score-weighted cohort of 183 adults with carbapenem-resistant Enterobacterales bacteremia at 24 US hospitals, patients receiving short courses of active therapy (7-10 days, median 9 days) experienced similar odds of recurrent bacteremia or death within 30 days as those receiving prolonged courses of active therapy (14-21 days, median 14 days).

Increase in antioxidant capacity associated with the successful subclone of hypervirulent carbapenem-resistant Klebsiella pneumoniae ST11-KL64

The acquisition of exogenous mobile genetic material imposes an adaptive burden on bacteria, whereas the adaptational evolution of virulence plasmids upon entry into carbapenem-resistant Klebsiella pneumoniae (CRKP) and its impact remains unclear. To better understand the virulence in CRKP, we characterize virulence plasmids utilizing a large genomic data containing 1219 K. pneumoniae from our long-term surveillance and publicly accessible databases. Phylogenetic evaluation unveils associations between distinct virulence plasmids and serotypes. The sub-lineage ST11-KL64 CRKP acquires a pK2044-like virulence plasmid from ST23-KL1 hypervirulent K. pneumoniae, with a 2698 bp region deletion in all ST11-KL64. The deletion is observed to regulate methionine metabolism, enhance antioxidant capacity, and further improve survival of hypervirulent CRKP in macrophages. The pK2044-like virulence plasmid discards certain sequences to enhance survival of ST11-KL64, thereby conferring an evolutionary advantage. This work contributes to multifaceted understanding of virulence and provides insight into potential causes behind low fitness costs observed in bacteria.

Efficacy and safety of ceftazidime-avibactam versus polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infection: a systematic review and meta-analysis

OBJECTIVES

Carbapenem-resistant Enterobacteriaceae is increasingly recognised as a significant public health concern. Ceftazidime-avibactam (CAZ-AVI) and polymyxins are considered as the last therapeutic options worldwide. This is the first meta-analysis of recently published data to compare the clinical efficacy and safety of CAZ-AVI with polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infections.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase and the Cochrane Library were systematically searched, for publications in any language, from database inception to February 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies comparing the clinical efficacy and safety of CAZ-AVI with polymyxins were included. Mortality, clinical success, microbiological eradication and nephrotoxicity were assessed as the main outcomes.

DATA EXTRACTION AND SYNTHESIS

Literature screening, data extraction and the quality evaluation of studies were conducted by two researchers independently, with disagreements resolved by another researcher. The Newcastle-Ottawa Scale was used to assess the bias risk for the included studies. Review Manager V.5.3 was employed for the meta-analysis.

RESULTS

The meta-analysis included seven retrospective and four prospective cohort studies with 1111 patients enrolled. The CAZ-AVI groups demonstrated a lower 30-day mortality (risk ratio (RR)=0.48, 95% CI of 0.37 to 0.63, I²=10%, p<0.0001) in nine studies with 766 patients; higher clinical success (RR=1.71, 95% CI 1.33 to 2.20, I²=35%, p<0.0001) in four studies with 463 patients; and lower nephrotoxicity in seven studies with 696 patients (RR=0.42, 95% CI 0.23 to 0.77, I²=35%, p<0.05). However, no significant difference in microbiological eradication rates was observed in 249 patients from two studies (RR=1.16, 95% CI 0.97 to 1.39, I²=0, p>0.05).

CONCLUSION

Available evidence suggested that CAZ-AVI treatment held a dominant position with respect to efficacy and safety compared with polymyxins in carbapenem-resistant Enterobacteriaceae infections. However, the analysis included only observational studies, and high-quality, large-scale, multicentre, double-blind randomised controlled trials are needed to confirm the advantage of CAZ-AVI.

A point mutation in recC associated with subclonal replacement of carbapenem-resistant Klebsiella pneumoniae ST11 in China

Adaptation to selective pressures is crucial for clinically important pathogens to establish epidemics, but the underlying evolutionary drivers remain poorly understood. The current epidemic of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant threat to public health. In this study we analyzed the genome sequences of 794 CRKP bloodstream isolates collected in 40 hospitals in China between 2014 and 2019. We uncovered a subclonal replacement in the predominant clone ST11, where the previously prevalent subclone OL101:KL47 was replaced by O2v1:KL64 over time in a stepwise manner. O2v1:KL64 carried a higher load of mobile genetic elements, and a point mutation exclusively detected in the recC of O2v1:KL64 significantly promotes recombination proficiency. The epidemic success of O2v1:KL64 was further associated with a hypervirulent sublineage with enhanced resistance to phagocytosis, sulfamethoxazole-trimethoprim, and tetracycline. The phenotypic alterations were linked to the overrepresentation of hypervirulence determinants and antibiotic genes conferred by the acquisition of an rmpA-positive pLVPK-like virulence plasmid and an IncFII-type multidrug-resistant plasmid, respectively. The dissemination of the sublineage was further promoted by more frequent inter-hospital transmission. The results collectively demonstrate that the expansion of O2v1:KL64 is correlated to a repertoire of genomic alterations convergent in a subpopulation with evolutionary advantages.

A Visualized Mortality Prediction Score Model in Hematological Malignancies Patients with Carbapenem-Resistant Organisms Bloodstream Infection

Background

Bloodstream infection (BSI) due to carbapenem-resistant organisms (CROs) has emerged as a worldwide problem associated with high mortality. This study aimed to evaluate the risk factors associated with mortality in HM patients with CROs BSI and to establish a scoring model for early mortality prediction.

Methods

We conducted a retrospective cohort study at our hematological department from January 2018 to December 2021, including all HM patients with CROs BSI. The outcome measured was death within 30-day of BSI onset. Survivor and non-survivor subgroups were compared to identify predictors of mortality. Univariate and multivariate Cox regression analyses were used to identify prognostic risk factors and develop a nomogram.

Results

In total, 150 HM patients were included in the study showing an overall 30-day mortality rate of 56%. Klebsiella pneumonia was the dominant episode. Cox regression analysis showed that pre-infection length of stay was >14 days (score 41), Pitt score >4 (score 100), mucositis (score 41), CAR (The ratio of C-reactive protein to albumin) >8.8 (score 57), early definitive therapy (score 44), and long-duration (score 78) were positive independent risk predictors associated with 30-day mortality, all of which were selected into the nomogram. Furthermore, all patients were divided into the high-risk group (≥160 points) or the low-risk group based on the prediction score model. The mortality of the high-risk group was 8 times more than the low-risk group. Kaplan-Meier analysis showed that empirical polymyxin B therapy was associated with a lower 30-day mortality rate, which was identified as a good prognostic factor in the high-risk group. In comparison, empirical carbapenems and tigecycline were poor prognostic factors in a low-risk group.

Conclusion

Our score model can accurately predict 30-day mortality in HM patients with CROs BSI. Early administration of CROs-targeted therapy in the high-risk group is strongly recommended to decrease mortality.

Development of a Risk Prediction Model of Subsequent Bloodstream Infection After Carbapenem-Resistant Enterobacteriaceae Isolated from Perianal Swabs in Hematological Patients

Purpose

Patients with hematological diseases are at high risk of carbapenem-resistant Enterobacteriaceae (CRE) infection, and CRE-related bloodstream infection (BSI) is associated with high mortality risk. Therefore, developing a predictive risk model for subsequent BSI in hematological patients with CRE isolated from perianal swabs could be used to guide preventive strategies.

Methods

This was a single-center retrospective cohort study at a tertiary blood diseases hospital, including all hematological patients hospitalized from 10 October 2017 to 31 July 2021. We developed a predictive model using multivariable logistic regression and internally validated it using enhanced bootstrap resampling.

Results

Of 421 included patients with CRE isolated from perianal swabs, BSI due to CRE occurred in 59. According to the multivariate logistic analysis, age (OR[odds ratio]=1.04, 95% CI[confidence interval]: 1.01-1.06, P=0.004), both meropenem and imipenem minimal inhibitory concentration (MIC) of the isolate from perianal swabs>8ug/mL (OR=5.34, 95% CI: 2.63-11.5, P<0.001), gastrointestinal symptoms (OR=3.67, 95% CI: 1.82-7.58, P<0.001), valley absolute neutrophil count (10⁹/L)>0.025 (OR=0.07, 95% CI: (0.02-0.19, P<0.001) and shaking chills at peak temperature (OR=6.94, 95% CI: (2.60-19.2, P<0.001) were independently associated with CRE BSI within 30 days and included in the prediction model. At a cut-off of prediction probability ≥ 21.5% the model exhibited a sensitivity, specificity, positive predictive value and negative predictive value of 79.7%, 85.6%, 96.27% and 47.47%. The discrimination and calibration of the prediction model were good on the derivation data (C-statistics=0.8898; Brier score=0.079) and enhanced bootstrapped validation dataset (adjusted C-statistics=0.881; adjusted Brier score=0.083). The risk prediction model is freely available as a mobile application at https://liujia1992.shinyapps.io/dynnomapp/.

Conclusion

A prediction model based on age, meropenem and imipenem MIC of isolate, gastrointestinal symptoms, valley absolute neutrophil count and shaking chills may be used to better inform interventions in hematological patients with CRE isolated from perianal swabs.

Risk Factors and Prognosis of Carbapenem-Resistant Organism Colonization and Infection in Acute Cholangitis

Background

To identify the risk factors and prognosis of carbapenem-resistant organisms (CRO) in patients with acute cholangitis.

Methods

This retrospective observational study was conducted to explore the risk factors and prognosis of CRO infection in 503 acute cholangitis patients diagnosed between July 2013 and January 2022 at the First Affiliated Hospital of Chongqing Medical University, who were divided into a CRO group and non-CRO group based on the presence or absence of CRO. Univariate, multivariate analyses, and the proportional hazards model were used to compare the risk factors and prognosis of CRO suffering in patients with acute cholangitis.

Results

We identified 35 patients colonized with CRO from 503 acute cholangitis patients. In the multivariate analysis, tumor (OR=7.09, 95% CI=1.11-45.30, P=0.038) and chronic kidney disease (OR=8.70, 95% CI=2.11-35.88, P=0.003) were ascertained as the risk factors of the occurrence on CRO infection under the background of acute cholangitis. CRO infection was identified as an independent risk factor for acute cholangitis patient death (HR=5.147, 95% CI=1.475-17.595, P=0.01) by Cox proportional-hazards regression.

Conclusion

Tumor and chronic kidney disease may be risk factors for CRO infection. Patients diagnosed with acute cholangitis further infected with CRO had a poor prognosis and a more severe mortality. Active screening for CRO is expected to facilitate early prevention, diagnosis, and treatment of high-risk patients.

A multicenter investigation of 2,773 cases of bloodstream infections based on China antimicrobial surveillance network (CHINET)

Background

Bloodstream infections (BSIs), especially hospital-acquired BSIs, are a major cause of morbidity and mortality. However, the details about the pathogens and antimicrobial resistance profile of BSIs across China are still lacking.

Methods

An investigation was conducted in 10 large teaching hospitals from seven geographic regions across China in 2016 based on China Antimicrobial Surveillance Network (CHINET) to profile the clinical and etiological features of BSIs.

Results

A total of 2,773 cases of BSIs were identified, a majority (97.3%) of which were monomicrobial. Overall, 38.4% (1,065/2,773) were community-acquired BSIs (CABSIs), and 61.6% (1,708/2,773) were hospital-acquired BSIs (HABSIs). Of the 2,861 pathogenic BSI isolates, 67.5% were Gram-negative bacteria, 29.6% were Gram-positive bacteria, and 2.9% were fungi. The top BSI pathogens were Escherichia coli, Klebsiella pneumoniae, coagulase-negative Staphylococci (CNS), Staphylococcus aureus, Enterococci, and Acinetobacter baumannii. Escherichia coli and K. pneumoniae isolates showed low susceptibility to penicillins, cephalosporins (except ceftazidime and cefepime), and ampicillin-sulbactam (13.1%-43.4% susceptible); moderate susceptibility (about 60% susceptible) to ceftazidime, cefepime, and aztreonam; and high susceptibility (>90%) to β-lactam/β-lactamase inhibitor combinations other than ampicillin-sulbactam, except K. pneumoniae strains to piperacillin-tazobactam (59.2% susceptible). HABSIs were associated with significantly higher prevalence of carbapenem-resistant and extended-spectrum β-lactamases-producing K. pneumoniae, methicillin-resistant S. aureus, methicillin-resistant CNS, and ampicillin-resistant Enterococci than CABSIs. Overall, 42.0% of the BSI due to S. aureus strains were resistant to methicillin.

Conclusions

The findings about BSIs in teaching hospitals across China add more scientific evidence to inform the appropriate management of the disease.

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 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.

Ceftazidime/Avibactam-Based Versus Polymyxin B-Based Therapeutic Regimens for the Treatment of Carbapenem-Resistant Klebsiella pneumoniae Infection in Critically Ill Patients: A Retrospective Cohort Study

INTRODUCTION

Considering the importance of ceftazidime/avibactam (CAZ/AVI) and polymyxin B (PMB) in treating carbapenem-resistant Klebsiella pneumoniae (CRKP) infection, it is essential to evaluate the efficacy and safety of these agents and provide appropriate medical advice to clinical specialists.

METHODS

We conducted a retrospective cohort study in two Chinese tertiary hospitals for critically ill patients with CRKP infection who received at least 24-h CAZ/AVI-based or PMB-based treatment. A binary logistic model and a Cox proportional hazards regression model were constructed to analyze variables that could potentially affect 30-day microbiological eradication and all-cause mortality, respectively.

RESULTS

From January 2019 to December 2021, 164 eligible patients were divided into CAZ/AVI and PMB cohorts. A notably lower 30-day mortality rate (35.4% vs 69.5%, P < 0.001) and a higher 30-day microbiological eradication rate (80.5% vs 32.9%, P < 0.001) were observed for patients receiving CAZ/AVI-based treatment, compared with cases in the PMB group. A longer antimicrobial treatment duration (> 7 days) could also significantly decrease the mortality rate and increase the microbiological eradication rate. Female patients had a higher survival rate than male patients. Age over 65 years, sepsis, continuous renal replacement therapy, and organ transplantation were identified as negative factors for survival. In the subgroup analysis, CAZ/AVI combined with tigecycline or amikacin could effectively lower mortality. According to safety evaluation results, potential elevation of hepatic enzymes was associated with CAZ/AVI-based treatment, while renal impairment was probably related to PMB-based treatment.

CONCLUSIONS

CAZ/AVI was more effective than PMB in treating CRKP-infected patients. Tigecycline and amikacin were proven to be beneficial as concomitant agents in combination with CAZ/AVI. A treatment period lasting over 7 days was recommended. Hepatoxicity of CAZ/AVI and nephrotoxicity of PMB should be monitored carefully. Further well-designed studies should be performed to verify our conclusion.

Efficacy and Safety of Ceftazidime-Avibactam for the Treatment of Carbapenem-Resistant Enterobacterales Bloodstream Infection: a Systematic Review and Meta-Analysis

Several clinicians use ceftazidime-avibactam (CAZ-AVI) to treat bloodstream infections (BSIs) due to carbapenem-resistant Enterobacterales (CRE), although no conclusive data support this practice. We aimed to assess the efficacy and safety of CAZ-AVI in the treatment of CRE bacteremia. PubMed, Embase, and Cochrane Library were systematically searched until 5 November 2021. Studies comparing the clinical outcome of CAZ-AVI with other regimens in CRE BSI were included if they reported data on mortality. Results were expressed as risk ratios (RRs) or mean differences with accompanying 95% confidence intervals (95% CIs). Eleven articles with 1,205 patients were included. CAZ-AVI groups showed a significantly lower 30-day mortality than control groups of other regimens (RR = 0.55, 95% CI of 0.45 to 0.68, P < 0.00001). The result is robust when a colistin-based regimen serves as the control group (RR = 0.48, 95% CI 0.33 of 0.69, P < 0.0001). In subgroup meta-analyses, the 30-day mortality was significantly lower in patients infected with CRE producing Klebsiella pneumoniae carbapenemase (RR = 0.59, 95% CI of 0.46 to 0.75, P < 0.0001). Additionally, patients in CAZ-AVI groups had a significantly higher clinical cure rate (RR = 1.75, 95% CI of 1.57 to 2.18, P < 0.00001) and lower nephrotoxicity rate (RR = 0.41, 95% CI of 0.20 to 0.84, P = 0.02). No significant differences of relapse rates were demonstrated in 2 groups (RR = 0.69, 95% CI of 0.29 to 1.66, P = 0.41). Although the current study is based on observational studies with a small sample of participants, the findings suggest that CAZ-AVI treatment is effective and safe compared with other antibiotics, including colistin, in CRE BSI.

IMPORTANCE Ceftazidime-avibactam (CAZ-AVI) has been used as a frontline agent in the treatment of multidrug-resistant (MDR) Gram-negative bacterial infections. However, the efficacy and safety of CAZ-AVI on carbapenem-resistant Enterobacterales (CRE) bloodstream infections (BSIs) remain unclear. Patients with CRE BSIs were often enrolled in small-sized clinical studies, together with other sites of infections, which reported pooled results. In this meta-analysis, the efficacy and safety were compared between CAZ-AVI and any other regimens used against CRE infections. The findings suggest that patients in the CAZ-AVI group had a significantly lower 30-day mortality than any other regimens and than colistin-based regimens. This paper provides a rationale for the use of CAZ-AVI in one of the most urgent antimicrobial-resistant infections of CRE bloodstream infections.

Emergence of Hypervirulent ST11-K64 Klebsiella pneumoniae Poses a Serious Clinical Threat in Older Patients

The carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) poses a severe therapeutic challenge to global public health, and research on CR-hvKP in older patients remain limited. In this study, we aimed to investigate the clinical and molecular characteristics and risk factors of CR-hvKP infections in older patients. We retrospectively investigated older patients with carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in the intensive care unit (ICU) between January 2020 and December 2020. The clinical data, and microbiological data including antimicrobial susceptibility testing, phenotype experiment and detection of carbapenemases, string test, virulence genes, capsular serotype-specific (cps) genes, and multilocus sequence typing, of the CR-hvKP group defined by the presence of any one of the virulence genes, including rmpA, rmpA2, iucA, iroN, and peg-344 were compared with those of CR-non-hvKP strains. Of the 80 CRKP strains, 51 (63.8%) met the definition of CR-hvKP. The main mechanism of resistance to carbapenems was the presence of the bla_KPC−2 gene. Sequence type (ST)11 (81.3%, 65/80) and ST15 (16.3%, 13/80) were the most common STs in CRKP strains. The minimum inhibitory concentration (MIC)₅₀ values of the CR-hvKP group against the six tested antibiotics (ceftazidime, ceftazidime-avibactam, imipenem-avibactam, tigecycline, levofloxacin, and Cefoperazone-Sulbactam) exhibited elevated levels than the CR-non-hvKP group. Ceftazidime and imipenem by combining avibactam (4 μg/mL) significantly decreased the MIC₉₀ values more than 16-fold than ceftazidime and imipenem alone against Klebsiella pneumoniae carbapenemase (KPC)-2-producing K. pneumoniae. Cardiovascular disease [odds ratio (OR) = 11.956] and ST11-K64 (OR = 8.385) appeared to be independent variables associated with CR-hvKP infection by multivariate analysis. In conclusion, higher MICs of the last line antibiotic agents (ceftazidime-avibactam, tigecycline) might be a critical consideration in the clinical management of older patients where the concentration of these toxic antibiotics matters because of underlying comorbidities. Caution regarding KPC-2-producing ST11-K64 CR-hvKP as being new significant “superbugs” is required as they are widespread, and infection control measures should be strengthened to curb further dissemination in nosocomial settings in China.

Treatment of Severe Infections Due to Metallo-Betalactamases Enterobacterales in Critically Ill Patients

Metallo-beta-lactamases-producing (MBL) Enterobacterales is a growing problem worldwide. The optimization of antibiotic therapy is challenging. The pivotal available therapeutic options are either the combination of ceftazidime/avibactam and aztreonam or cefiderocol. Colistin, fosfomycin, tetracyclines and aminoglycosides are also frequently effective in vitro, but are associated with less bactericidal activity or more toxicity. Prior to the availability of antibiotic susceptibility testing, severe infections should be treated with a combination therapy. A careful optimization of the pharmacokinetic/pharmacodynamic properties of antimicrobials is instrumental in severe infections. The rules of antibiotic therapy are also reported and discussed. To conclude, treatment of severe MBL infections in critically ill patients is difficult. It should be individualized with a close collaboration of intensivists with microbiologists, pharmacists and infection control practitioners.

Assessment of Mortality-Related Risk Factors and Effective Antimicrobial Regimens for Treatment of Bloodstream Infections Caused by Carbapenem-Resistant Enterobacterales

Bloodstream infections (BSIs) attributable to carbapenem-resistant Enterobacterales (CRE-BSIs) are dangerous and a major cause of mortality in clinical settings. This study was therefore designed to define risk factors linked to 30-day mortality in CRE-BSI patients and to examine the relative efficacies of different antimicrobial treatment regimens in affected individuals. Data pertaining to 187 CRE-BSI cases from four teaching hospitals in China collected between January 2018 and December 2020 were retrospectively analyzed. For the 187 patients analyzed in this study, the 30-day mortality of CRE-BSI was 41.7% (78/187). Multivariate logistic regression analyses revealed that Pitt bacteremia score, immunocompromised status, meropenem MIC of ≥8 mg/liter,absence of source control of infection, and appropriate empirical therapy were independent predictors of CRE-BSI patient 30-day mortality. After controlling for potential confounding factors relative to ceftazidime-avibactam (CAZ-AVI) treatment, combination therapies including CAZ-AVI (odds ratio [OR], 1.287; 95% confidence interval [CI], 0.124 to 13.403; P = 0.833) were not related to any significant change in patient mortality risk, whereas the 30-day mortality risk was higher for patients administered other antimicrobial regimens (OR, 12.407; 95% CI, 1.684 to 31.430; P = 0.011). When patients were treated with antimicrobial regimens not containing CAZ-AVI, combination therapy (OR, 0.239; 95% CI, 0.077 to 0.741; P = 0.013) was related to a decreased 30-day mortality risk relative to monotherapy treatment. The mortality-related risk factors and relative antimicrobial regimen efficacy data demonstrated in this study may guide the management of CRE-BSI patients.

Bloodstream infections in adult patients with malignancy, epidemiology, microbiology, and risk factors associated with mortality and multi-drug resistance

Background

This study aimed to investigate the epidemiology, microbiology, and risk factors associated with mortality and multi-drug resistance bacterial bloodstream infections (BSIs) among adult cancer patients in Shiraz, Iran. We also report a four-year trend of antimicrobial resistance patterns of BSIs.

Methods

We conducted a retrospective study at a referral oncology hospital from July 2015 to August 2019, which included all adults with confirmed BSI.

Results

2393 blood cultures tested during the four-year study period; 414 positive cultures were included. The mean age of our patients was 47.57 ± 17.46 years old. Central Line-Associated BSI (CLABSI) was more common in solid tumors than patients with hematological malignancies. Gram-negative (GN) bacteria were more detected (63.3%, 262) than gram-positive bacteria (36.7%, 152). Escherichia coli was the most common gram-negative organism (123/262, 47%), followed by Pseudomonas spp. (82/262, 31%) and Klebsiella pneumoniae (38/262, 14.5%). Coagulase-negative staphylococci (CoNS) was the most frequently isolated pathogen among gram-positive bacteria (83/152, 54.6%). Acinetobacter spp., Pseudomonas spp., E. coli, and K. pneumoniae were the most common Extended-Spectrum Beta-Lactamase (ESBL) producers (100, 96.2, 66.7%, and 60.7, respectively). Acinetobacter spp., Pseudomonas spp., Enterobacter spp., E. coli, and K. pneumoniae were the most common carbapenem-resistant (CR) isolates (77.8, 70.7, 33.3, 24.4, and 13.2%, respectively). Out of 257 Enterobacterales and non-fermenter gram-negative BSIs, 39.3% (101/257) were carbapenem-resistant. Although the incidence of multi-drug resistance (MDR) gram-negative BSI increased annually during 2015–2018, the mortality rate of gram-negative BSI remains unchanged at about 20% (p-value = 0.55); however, the mortality rate was significantly greater (35.4%) in those with resistant gram-positive BSI (p-value = 0.001). The overall mortality rate was 21.5%. Early (7-day mortality) and late mortality rate (30-day mortality) were 10 and 3.4%, respectively.

Conclusions

The emergence of MDR gram-negative BSI is a significant healthcare problem in oncology centers. The high proportion of the most frequently isolated pathogens were CR and ESBL-producing Enterobacterales and Pseudomonas spp. We have few effective choices against MDRGN BSI, especially in high-risk cancer patients, which necessitate newer treatment options.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06243-z.