Risk Factors and Outcomes of Antibiotic-resistant Pseudomonas aeruginosa Bloodstream Infection in Adult Patients With Acute Leukemia

Risk factors and outcome of Pseudomonas aeruginosa bloodstream infections (PABSI) in hematological patients: a single center retrospective cohort study

PURPOSE

Bloodstream infections caused by Pseudomonas aeruginosa (PABSI) in hematological patients are associated with high morbidity and mortality. We investigated the epidemiology, risk factors, and outcomes of PABSI at our center.

METHODS

All adult hematological patients with PABSI between January 2013 and July 2023 were included. Demographic and clinical characteristics, antimicrobial susceptibilities, antibiotic therapy, fluoroquinolone-prophylaxis, source of infection, and 30-day outcome were recorded. Descriptive statistics, tests for difference, and logistic regression models were performed.

RESULTS

Fifty patients with PABSI were identified with a median age of 58.5 years (range 24-78). 37 patients (74%) had severe neutropenia, 20 (40%) received allogeneic HSCT, and 29 (58%) had acute leukemia. A total of 34 (68%) had received timely appropriate anti-pseudomonal antibiotic therapy. The most common presumed cause of PABSI was mucositis (n = 16, 32%), followed by pneumonia (8, 16%) and skin and soft tissue infections (n = 6, 12%). Empirical combination therapy was used in 16 (32%) patients, while targeted combination therapies were used in 27 (54%) patients. P. aeruginosa detection led to treatment change in 31 (62%) cases. The overall 30-day survival rate was 78% (n = 39). Carbapenem-resistance occurred in 34% (n = 17), and multidrug-resistance (MDR) in 20% (n = 10). Prior antibiotic exposure was associated with resistance. Appropriate antibiotic therapy was associated with survival, whereas antibiotic resistance and organ infection were associated with a fatal outcome.

CONCLUSION

Prior antibiotic exposure in hematological patients is associated with resistance in PABSI, which is a major risk factor for a fatal outcome. Antibiotic stewardship efforts should be intensified and fluoroquinolone prophylaxis needs to be reconsidered.

Clinical characteristics and prognosis of bloodstream infections with carbapenem-resistant Gram-negative organisms in patients with hematological malignancies: A multicenter case-control study in China

OBJECTIVE

To investigate clinical characteristics of hematological malignancy (HM) patients with carbapenem-resistant gram-negative organism (CRO) bloodstream infections (BSI) in China, and to elucidate the prognostic risk factors of CRO BSI.

METHODS

We conducted a multicenter case-control study of 201 HM patients with CRO BSI between 2018-2020. Antimicrobial susceptibility testing and whole genome sequencing were performed for CRO isolates. Independent risk factors for 28-day crude mortality were analyzed using Cox proportional hazards regression models. The subgroups of major species were also evaluated.

RESULTS

The pathogens responsible for CRO BSI in HM patients dominated by ST11 CRKP, ST167 CREC and ST463 CRPA. Most isolates produced carbapenemases with KPC and NDM being the main. CRO isolates had resistance rates to conventional antimicrobials ranging from 55%-100% and poor susceptibility to novel antimicrobials related to carbapenemases and species. The 28-day crude mortality was 24.2%. Non-Hodgkin lymphoma, heart disease, blaKPC-2 positive, empirical antibiotic therapy with linezolid, Pitt bacteremia score >3.5 were risk factors for 28-day mortality and appropriate definitive antibiotic therapy, tigecycline-containing therapy and aminoglycoside-containing therapy were protective factors. blaKPC-2 positive in CRKP and ST463 in CRPA were associated with Pitt bacteremia score >3.5. Solid tumor and other site infections before BSI were risk factors for ST463 CRPA BSI and pulmonary infection before BSI was risk factor for KPC-KP BSI.

CONCLUSIONS

The antimicrobial resistance of CRO isolates for BSI in HM patients is critical. HM patients with CRO BSI should be treated with appropriate definitive antibiotic therapy based on early clarification of pathology and their antimicrobial susceptibility.

Adult acute leukemia patients with gram-negative bacteria bloodstream infection: Risk factors and outcomes of antibiotic-resistant bacteria

This study aims to analyze the risk factors for the development of multidrug-resistant (MDR) and carbapenem-resistant (CR) bacteria bloodstream infection (BSI) in a patient with acute leukemia (AL) and the mortality in gram-negative bacteria (GNB) BSI. This is a retrospective study conducted at West China Hospital of Sichuan University, which included patients diagnosed with AL and concomitant GNB BSI from 2016 to 2021. A total of 206 patients with GNB BSI in AL were included. The 30-day mortality rate for all patients was 26.2%, with rates of 25.8% for those with MDR GNB BSI and 59.1% for those with CR GNB BSI. Univariate and multivariate analyses revealed that exposure to quinolones (Odds ratio (OR) = 3.111, 95% confidence interval (95%CI): 1.623-5.964, p = 0.001) within the preceding 30 days was an independent risk factor for MDR GNB BSI, while placement of urinary catheter (OR = 6.311, 95%CI: 2.478-16.073, p < 0.001) and exposure to cephalosporins (OR = 2.340, 95%CI: 1.090-5.025, p = 0.029) and carbapenems (OR = 2.558, 95%CI: 1.190-5.497, p = 0.016) within the preceding 30 days were independently associated with CR GNB BSI. Additionally, CR GNB BSI (OR = 2.960, 95% CI: 1.016-8.624, p = 0.047), relapsed/refractory AL (OR = 3.035, 95% CI: 1.265-7.354, p = 0.013), septic shock (OR = 5.108, 95% CI: 1.794-14.547, p = 0.002), platelets < 30 × 109/L before BSI (OR = 7.785, 95% CI: 2.055-29.492, p = 0.003), and inappropriate empiric antibiotic therapy (OR = 3.140, 95% CI: 1.171-8.417, p = 0.023) were independent risk factors for 30-day mortality in AL patients with GNB BSI. Prior antibiotic exposure was a significant factor in the occurrence of MDR GNB BSI and CR GNB BSI. CR GNB BSI increased the risk of mortality in AL patients with GNB BSI.

Rapid diagnosis of Aspergillus flavus infection in acute very severe aplastic anemia with metagenomic next-generation sequencing: a case report and literature review

Infection remains the leading cause of mortality in severe aplastic anemia (SAA) patients, with invasive fungal infections being the great threat. Aspergillus fumigatus accounts for most of the reported fungal infection cases. Here, we present a case of A. flavus infection in a patient with acute very severe aplastic anemia (VSAA) despite persistently negative clinical fungal tests. The patient was admitted to the hospital due to pancytopenia presisting for over a month and intermittent fever for 10 days. Elevated inflammatory indicators and abnormal lung imaging suggested infection, prompting consideration of fungal involvement. Despite negative results from multiple blood, sputum fungal cultures and the serum (1,3)-β-D-glucan/galactomannan tests. Metagenomic next-generation sequencing (mNGS) on multiple blood samples, alongside clinical symptoms, confirmed A. flavus infection. Targeted antifungal treatment with liposomal amphotericin B and voriconazole significantly ameliorated pulmonary symptoms. Additionally, this study reviewed and compared the symptoms, diagnostic approaches, and treatments from prior Aspergillus infections in AA patients. It emphasizes critical role of early mNGS utilization in diagnosing and managing infectious diseases, offering insights for diagnosing and treating fungal infections in VSAA.

Characterization of the Pathogen Distribution and Drug Resistance in Bloodstream Infections During COVID-19 Pandemic in a Tertiary Hospital in Eastern China: Comparison with the Pre-Pandemic Period

Purpose

To explore the characteristics of the pathogen distribution and drug resistance in bloodstream infections (BSIs) during the COVID-19 pandemic in a tertiary hospital in eastern China, and to compare them with those before the pandemic.

Patients and Methods

Non-repetitive strain data of BSIs were retrospectively obtained before the COVID-19 pandemic (Pre-Pandemic, n=2698) and during the COVID-19 pandemic (Pandemic, n=2922), the distribution of pathogens and drug resistance were compared between the two groups.

Results

The main pathogens of BSIs were Gram-negative bacteria (57.91%), followed by Gram-positive bacteria (32.58%), fungi and anaerobic bacteria accounting for 5.48% and 3.39%, respectively. Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus were the top 3 isolates. The proportion of Serratia marcescens, Enterobacter aerogenes, Enterococcus faecium, Enterococcus faecalis and Candida tropicalis were significantly increased, while those of Pseudomonas aeruginosa, Streptococcus sanguinis and Streptococcus pneumoniae were significantly decreased when compared to the Pre-Pandemic (P<0.05). Carbapenem-resistant Enterobacterales (CRE) significantly elevated during the Pandemic (17.4% vs 14.4%, P=0.041); the detection of carbapenem-resistant Pseudomonas aeruginosa (CRPA) significantly ascended (39.0% vs 24.4%, P=0.016); and the proportion of carbapenem-resistant Acinetobacter baumannii (CRAB) maintained stable (78.8%). Gram-positive bacteria had the lowest resistance to linezolid, vancomycin and tigecycline, which remained a stable trend with the Pre-Pandemic (<5.0%). The isolate rates of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) were 38.9% and 1.0%, respectively. Staphylococcus aureus showed a decrease in the isolation rate of vancomycin minimum inhibitory concentration (MIC) ≤ 0.5 μg/mL (χ2=7.676, P=0.006) and an increase with vancomycin MIC=1 μg/mL (χ2=9.008, P=0.003).

Conclusion

The pathogen distribution and drug resistance of BSIs during the COVID-19 pandemic were transformed from Pre-Pandemic and accompanied by increasing bacterial resistance. Clinical management of antibiotic application and infection control should be strengthened.

Impact of multidrug resistance on the virulence and fitness of Pseudomonas aeruginosa: a microbiological and clinical perspective

Pseudomonas aeruginosa is one of the most common nosocomial pathogens and part of the top emergent species associated with antimicrobial resistance that has become one of the greatest threat to public health in the twenty-first century. This bacterium is provided with a wide set of virulence factors that contribute to pathogenesis in acute and chronic infections. This review aims to summarize the impact of multidrug resistance on the virulence and fitness of P. aeruginosa. Although it is generally assumed that acquisition of resistant determinants is associated with a fitness cost, several studies support that resistance mutations may not be associated with a decrease in virulence and/or that certain compensatory mutations may allow multidrug resistance strains to recover their initial fitness. We discuss the interplay between resistance profiles and virulence from a microbiological perspective but also the clinical consequences in outcomes and the economic impact.

Mechanisms of action of berberine hydrochloride in planktonic cells and biofilms of Pseudomonas aeruginosa

The increasing prevalence of extensively drug-and pan-drug-resistant Pseudomonas aeruginosa is a major concern for global public health. Therefore, it is crucial to develop novel antimicrobials that specifically target P. aeruginosa and its biofilms. In the present study, we determined that berberine hydrochloride inhibited the growth of planktonic bacteria as well as prevented the formation of biofilms. Moreover, we observed downregulation in the expression of pslA and pelA biofilm-related genes. Compared with existing antibiotics, berberine hydrochloride exhibits multiple modes of action against P. aeruginosa. Our findings suggest that berberine hydrochloride exerts its antimicrobial effects by damaging bacterial cell membranes, generating reactive oxygen species (ROS), and reducing intracellular adenosine triphosphate (ATP) levels. Furthermore, berberine hydrochloride showed minimal cytotoxicity and reduced susceptibility to drug resistance. In a mouse model of peritonitis, it significantly inhibited the growth of P. aeruginosa and exhibited a strong bacteriostatic action. In conclusion, berberine hydrochloride is a safe and effective antibacterial agent that inhibits the growth of P. aeruginosa.

Ceftazidime-avibactam in the treatment of bacteremia due to carbapenem-resistant gram-negative bacteria in hematological patients: Experience in a single center

INTRODUCTION

Limited experience exists with ceftazidime-avibactam (CAZ-AVI) in treating bacteremia caused by carbapenem-resistant Enterobacterales (CRE) and Pseudomonas aeruginosa (CRPA) in hematological patients.

METHODS

We performed a single-center, retrospective, observational study including patients who received CAZ-AVI for bacteremia due to CRE or CRPA between 2018 and 2022. The primary outcome was 30-day survival. We conducted a multivariable analysis to identify predictors of survival.

RESULTS

56 patients were included and 57 (41 CRE and 16 CRPA) strains were isolated. 35 strains produced carbapenemase, including 25 metallo-beta-lactamase (MBL) and 10 serine-beta-lactamase. 48 patients (85.7 %) received combination therapy. All patients with MBL-CRE bacteremia (n = 24) received combination therapy with aztreonam (AZT). The susceptibility rates to CAZ-AVI were only 26.8 % (11/41) in CRE and 80.0 % (8/10) in CRPA. The 30-day survival rates were 85.0 % (34/40) in the CRE group and 81.3 % (13/16) in the CRPA group. In patients with MBL-CRE bacteremia, the 30-day survival was as high as 91.7 % (22/24) due to combination with AZT. Ceftazidime did not influence the activity of aztreonam-avibactam against MBL-CRE in-vitro. Multivariable cox analysis revealed neutropenia >14 days (P = 0.002, HR: 34.483, 95%CI: 3.846-333.333) and a higher Pitt bacteremia score (P = 0.005, HR: 2.074, 95%CI: 1.253-3.436) were risk factors for 30-day survival.

CONCLUSIONS

CAZ-AVI is highly effective in treating bacteremia due to CRPA and serine-beta-lactamase CRE. The combination of avibactam with AZT is highly effective in treating bacteremia due to AZT-resistant MBL producers.

Mortality associated with carbapenem resistance in Klebsiella pneumoniae bloodstream infection: A propensity score-matched study

OBJECTIVE

Klebsiella pneumoniae are common pathogens causing bloodstream infection (BSI) that increasingly express carbapenem resistance worldwide. To date, no study has precisely investigated the impact of carbapenem resistance in K. pneumoniae (CRKP) BSI on mortality.

METHODS

This retrospective study included 87 patients with CRKP BSI and 321 patients with carbapenem-susceptible K. pneumoniae (CSKP) BSI from 2015 to 2020. Propensity score analyses with stabilized inverse probability of treatment weighting (IPTW-S) was applied to balance covariates. The hazard ratio for 30-day mortality associated with carbapenem resistance was estimated using Cox regression and Kaplan-Meier curves.

RESULTS

The 30-day crude mortality rates were 43.7% in patients with CRKP BSI and 17.8% in patients with CSKP BSI (P < .001). Age ≥55 years, underlying hematological malignancies and hemodialysis were independently associated with mortality in CRKP BSI. A skin or soft-tissue infection source, urinary catheter, and underlying chronic obstructive pulmonary disease were predictors of mortality in CSKP BSI. The group characteristics were well balanced after IPTW-S. The adjusted hazard ratio for 30-day mortality for CRKP BSI was 1.607 (interquartile range, 0.814-3.171).

CONCLUSIONS

Carbapenem resistance was not associated with a significant increase in 30-day mortality in KP BSI; patient and disease factors were primary determinants of outcomes.

Risk factors and mortality of carbapenem-resistant Pseudomonas aeruginosa bloodstream infection in haematology department: A 10-year retrospective study

OBJECTIVES

This study aims to investigate the risk factors for carbapenem-resistant Pseudomonas aeruginosa bloodstream infection (CRPA-BSI) and identify predictors of outcomes among patients with P. aeruginosa bloodstream infection (PA-BSI).

METHODS

A retrospective cohort study was conducted on patients with PA-BSI at Henan Cancer Hospital from 2013 to 2022.

RESULTS

Among the 503 incidences analysed, 15.1% of them were CRPA strains. Age, ANC < 100/mmc, receiving antifungal prophylaxis, exposure to carbapenems within the previous 90 days to onset of BSI, and allogeneic HSCT (allo-HSCT) were associated with the development of CRPA-BSI. CRPA-BSI patients experienced significantly higher 28-day mortality rates compared to those with carbapenem-susceptible P. aeruginosa bloodstream infection. Multivariate logistic regression analysis identified age at BSI, active stage of haematological disease, procalcitonin levels, prior corticosteroid treatment, isolation of CRPA, and septic shock as independent predictors of 28-day mortality.

CONCLUSIONS

Risk factors for CRPA-BSI include age, ANC < 100/mmc, antifungal prophylaxis, exposure to carbapenems, and allo-HSCT. Additionally, age at BSI, active haematological disease, procalcitonin levels, prior corticosteroid treatment, CRPA isolation, and septic shock contribute to increased mortality rates among patients with PA-BSI.

Screening for multidrug-resistant organisms in high-risk hospitalized patients with hematologic diseases

OBJECTIVES

Patients treated for hematologic malignancies are at higher risk for blood stream infections (BSI) and multidrug-resistant organisms (MDRO) are increasingly involved. Studies showed a significant association between rectal colonization status and a higher risk of subsequent MDRO BSI. The objective of our study was to probe the practice of surveillance cultures in Belgian hematology centers.

METHODS

A questionnaire was sent to the 13 hematology centers participating in the acute leukemia board of the Belgian Hematology Society. 21 questions probed for the method of surveillance cultures, MDRO screened, antimicrobial prophylaxis, and empirical therapy and their relationship with colonization status.

RESULTS

All centers completed the questionnaire in full. Routine gastrointestinal surveillance cultures in hematologic patients are taken in 10 hospitals. Organisms tested for included mostly ESBL (n = 9) and carbapenem-resistant (n = 8) Enterobacterales. All centers with a screening strategy adapt empiric antibiotic therapy based on MDRO colonization. Prophylaxis strategies are variable, only two centers adapt prophylaxis upon documentation of fluoroquinolone resistance.

CONCLUSIONS

The majority of the Belgian centers perform routine surveillance cultures and adapt empiric therapy for neutropenic fever accordingly. Other reasons for testing include to gain insight into local epidemiology and to prevent in-hospital transmission. In general, there was significant variability in surveillance dimensions.

Antimicrobial metabolites produced by endophytic fungi associated with the leaves of Vochysia divergens

Investigation of the endophytic fungi Nigrospora sphaerica, Nigrospora oryzae, and Pseudofusicoccum stromaticum MeOH fractions isolated from the leaves of Vochysia divergens, a medicinal species from the Brazilian Pantanal, led to the identification of five compounds, namely a new compound (1E,8Z)-10,11-dihydroxy-5,5,8-trimethyl-4-oxocycloundeca-1,8-diene-1-carbaldehyde (1) and four known compounds: 5-methylmellein (2), sclerone (3), daldinone A (4), and lasiodiplodin (5). All compounds were identified using spectroscopic methods, and 1 was corroborated with mass spectrometry, while the known compounds were compared with data in the literature. The relative configuration of compound 1 was determined based on theoretical conformational studies as well as the J experimental values between the hydroxymethyne hydrogens. The antimicrobial activity of the compounds was evaluated. Promising results were obtained for compounds 2, 4, and 5 since they inhibited the bacterium Pseudomonas aeruginosa, an opportunistic pathogen, suggesting the potential of these microorganisms as a source of new antibacterial agents.

Changing epidemiology, microbiology and mortality of bloodstream infections in patients with haematological malignancies before and during SARS-CoV-2 pandemic: a retrospective cohort study

OBJECTIVE

This study was to explore the changes in bacterial bloodstream infection (BSI) in patients with haematological malignancies (HMs) before and during SARS-CoV-2 pandemic.

DESIGN

Retrospective cohort study between 2018 and 2021.

SETTING

The largest haematological centre in southern China.

RESULTS

A total of 599 episodes of BSI occurring in 22 717 inpatients from January 2018 to December 2021 were analysed. The frequencies of the total, Gram-negative and Gram-positive BSI before and during the pandemic were 2.90% versus 2.35% (p=0.011), 2.49% versus 1.77% (p<0.001) and 0.27% versus 0.44% (p=0.027), respectively. The main isolates from Gram-negative or Gram-positive BSI and susceptibility profiles also changed. The 30-day mortality caused by BSI was lower during the pandemic (21.1% vs 14.3%, p=0.043). Multivariate analysis revealed that disease status, pulmonary infection and shock were independent predictors of 30-day mortality.

CONCLUSION

Our data showed that the incidence of total and Gram-negative organisms BSI decreased, but Gram-positive BSI incidence increased in patients with HMs during the pandemic along with the changes of main isolates and susceptibility profiles. Although the 30-day mortality due to BSI was lower during the pandemic, the new infection prevention strategy should be considered for any future pandemics.

Management strategies for severe Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

This review focuses on the management of severe Pseudomonas aeruginosa infections in critically ill patients.

RECENT FINDINGS

Pseudomonas aeruginosa is the most common pathogen in intensive care; the main related infections are nosocomial pneumonias, then bloodstream infections. Antimicrobial resistance is common; despite new antibiotics, it is associated with increased mortality, and can lead to a therapeutic deadlock.

SUMMARY

Carbapenem resistance in difficult-to-treat P. aeruginosa (DTR-PA) strains is primarily mediated by loss or reduction of the OprD porin, overexpression of the cephalosporinase AmpC, and/or overexpression of efflux pumps. However, the role of carbapenemases, particularly metallo-β-lactamases, has become more important. Ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam are useful against DTR phenotypes (noncarbapenemase producers). Other new agents, such as aztreonam-ceftazidime-avibactam or cefiderocol, or colistin, might be effective for carbapenemase producers. Regarding nonantibiotic agents, only phages might be considered, pending further clinical trials. Combination therapy does not reduce mortality, but may be necessary for empirical treatment. Short-term treatment of severe P. aeruginosa infections should be preferred when it is expected that the clinical situation resolves rapidly.

Acinetobacter spp. bloodstream infection in hematological patients: a 10-year single-center study

PURPOSE

This study investigated the clinical and antimicrobial characteristics of Acinetobacter spp. bloodstream infection (BSI) in hematological patients. Risk factors for 30-day mortality and carbapenem-resistant Acinetobacter spp. (CRA) BSI acquisition were also identified.

METHODS

We reviewed forty hematological patients with Acinetobacter spp. BSI in a large Chinese blood disease hospital between 2013 and 2022. The remaining CRA isolates were subjected to whole-genome sequencing.

RESULTS

The 30-day mortality rate was high at 35%. Hematological patients with Acinetobacter spp. BSI often presented with severe conditions and co-infections at multiple sites. All strains were colistin-susceptible and 40.0% were CR. Multivariate analysis identified several risk factors associated with CRA BSI acquisition, including previous exposure to carbapenems within 30 days and CRA colonization. Very severe aplastic anaemia, tetracycline-resistant Acinetobacter spp. BSI, and unresolved neutropenia after infection were closely associated with 30-day mortality. Non-survivors often presented with higher median PCT and CRP levels and severe complications, such as intracranial infection, cardiac dysfunction, respiratory failure, and severe sepsis or septic shock. Our study also identified inappropriate empirical antibiotic therapy as an independent predictor of 30-day mortality (OR: 11.234, 95% CI: 1.261-20.086, P = 0.030). This study was the first to report A. oleivorans as a human pathogen, and to identify its unique oxacillinase, OXA-325.

CONCLUSION

An environment-originated non-pathogenic species can become pathogenic when the body's immunity is compromised. Our results also highlighted the importance of improving neutropenia after infection, treating severe organ dysfunction, and administering appropriate empirical antibiotic therapy to reduce mortality in this patient population.

Global impact of antibacterial resistance in patients with hematologic malignancies and hematopoietic cell transplant recipients

Patients with hematologic malignancies and hematopoietic cell transplant (HCT) recipients are at high risk of developing bacterial infections. These patients may suffer severe consequences from these infections if they do not receive immediate effective therapies, and thus are uniquely threatened by antimicrobial-resistant bacteria. Here, we outline how the emergence of specific resistant bacteria threatens the effectiveness of established approaches to prevent and treat infections in this population. The emergence of fluoroquinolone resistance among Enterobacterales and viridans group streptococci may decrease the effectiveness of fluoroquinolone prophylaxis during neutropenia. The emergence of Enterobacterales that produce extended-spectrum β-lactamases or carbapenemases and of increasingly resistant Pseudomonas aeruginosa may result in neutropenic patients experiencing delayed time to active antibacterial therapy, and consequently worse clinical outcomes. The ability to select targeted antibacterial therapies after the availability of susceptibility data may be limited in patients infected with metallo-β-lactamase-producing Enterobacterales and difficult-to-treat P. aeruginosa. Vancomycin-resistant enterococci and Stenotrophomonas maltophilia can cause breakthrough infections in patients already being treated with broad-spectrum β-lactam antibiotics. Resistance can also limit the ability to provide oral stepdown antibacterial therapy for patients who could otherwise be discharged from hospitalization. We also outline strategies that have the potential to mitigate the negative impact of antimicrobial resistance, including interventions based on active screening for colonization with resistant bacteria and the use of novel rapid diagnostic assays. Additional research is needed to better understand how these strategies can be leveraged to combat the emerging crisis of antimicrobial resistance in patients with hematologic malignancies and HCT recipients.

Evaluation and analysis of multidrug resistance- and hypervirulence-associated genes in carbapenem-resistant Pseudomonas aeruginosa strains among children in an area of China for five consecutive years

Introduction

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a growing threat. It is urgent to investigate the multidrug resistance and high virulence of CRPA to provide a basis for infection control and rational use of antibiotics.

Methods

A retrospective study of 56 nonduplicated CRPA isolates was conducted.

Results

CRPA mainly came from the intensive care unit (ICU) and was mostly isolated from sputum samples. The carbapenem resistance rates of P. aeruginosa were 21.37% (2016), 10.62, 5.88, 10 and 13.87% from 2016 to 2020, respectively. Carbapenem-resistant enzymes and aminoglycoside-modifying enzyme-encoding genes were detected in all isolates, and extended-spectrum β-lactamase and cephalosporin enzyme-encoding genes were present in 96.43 and 80.38% of isolates, respectively. The detection rate of OprM showed a statistically significant difference (p < 0.05) between the ICU and other wards. Genes related to biofilms, membrane channel proteins, I integrons and efflux systems were detected in all isolates, with detection rates greater than 90%. CRPA was strongly virulent, and over 80% of isolates carried hypervirulence-associated genes (exoU, exoS, exoT, and exoY). The drug resistance rates of cefepime and piperacillin/tazobactam showed a statistically significant difference (p < 0.05) between strains with exoU (+) and exoU (-) (p < 0.05). Notably, out of the 7 individuals who died, 4 had extensively drug-resistant P. aeruginosa (57.14%).

Discussion

The detection rates of various resistance and virulence genes were high, and the coexistence phenomenon was serious. In clinical practice, antibiotics should be used reasonably based on different drug resistance genes to ensure the rationality and safety of patient medication.

Clinical characteristics of bloodstream infections in adult patients with solid tumours and a nomogram for mortality prediction: a 5-year case-controlled retrospective study in a tertiary-level hospital

Background

Bloodstream infections (BSIs) are one of the leading causes of death in cancer patients. Nevertheless, the risk factors of BSIs in solid tumors have rarely been ascertained adequately.

Methods

We conducted a single-center case-controlled retrospective study from 2017 to 2021 among adults with solid tumors in a tertiary-level hospital. The BSIs and control group were matched by the propensity score matching method. We found independent risk factors of occurrence and death of BSIs using univariate and multivariate regression analysis. Additionally, a nomogram was constructed to predict the risk of mortality in BSIs.

Results

Of 602 patients with solid tumors in the study period, 186 had BSIs and 416 had non-BSIs. The incidence of BSIs was 2.0/1,000 admissions (206/102,704), and the 30-day mortality rate was 18.8% (35/186). Compared to the control group, the BSIs had longer hospital stays (24.5 days vs. 20.0 days), and higher frequency complicating with organ failure (10.5% vs. 2.4%), nephropathy (19.6% vs. 3.8%), comorbidities≥3 (35.5% vs. 20.0%), and liver-biliary-pancreatic infections (15.6% vs. 5.3%) (all P<0.001). Among the 186 patients with BSIs, 35 died within 30 days after BSIs. Gram-negative bacteria were the most frequent microorganisms (124/192, 64.6%). Liver cancer, organ failure, a high level of lactate dehydrogenase and septic shock were the independent hazardous factors for death of BSIs. What's more, a nomogram was constructed to predict the 30-day survival rate of BSIs, which was proved to have good accuracy (AUC: 0.854; 95% confidence interval: 0.785~0923) and consistency.

Conclusion

Being aware of the risk factors of BSIs redounds to take preventive measures to reduce the incidence and death of BSIs.

Microbiology and prognostic prediction model of bloodstream infection in patients with hematological malignancies

Background

In recent years, with the continuous development of treatments for hematological malignancies (HMs), the remission and survival rates of patients with HMs have been significantly improved. However, because of severe immunosuppression and long-term recurrent neutropenia during treatment, the incidence and mortality of bloodstream infection (BSI) were all high in patients with HMs. Therefore, we analyzed pathogens' distribution and drug-resistance patterns and developed a nomogram for predicting 30-day mortality in patients with BSIs among HMs.

Methods

In this retrospective study, 362 patients with positive blood cultures in HMs were included from June 2015 to June 2020 at West China Hospital of Sichuan University. They were randomly divided into the training cohort (n = 253) and the validation cohort (n = 109) by 7:3. A nomogram for predicting 30-day mortality after BSIs in patients with HMs was established based on the results of univariate and multivariate logistic regression. C-index, calibration plots, and decision curve analysis were used to evaluate the nomogram.

Results

Among 362 patients with BSIs in HMs, the most common HM was acute myeloid leukemia (48.1%), and the most common pathogen of BSI was gram-negative bacteria (70.4%). The final nomogram included the septic shock, relapsed/refractory HM, albumin <30g/l, platelets <30×10⁹/l before BSI, and inappropriate empiric antibiotic treatment. In the training and validation cohorts, the C-indexes (0.870 and 0.825) and the calibration plots indicated that the nomogram had a good performance. The decision curves in both cohorts showed that the nomogram model for predicting 30-day mortality after BSI was more beneficial than all patients with BSIs or none with BSIs.

Conclusion

In our study, gram-negative bacterial BSIs were predominant in patients with HMs. We developed and validated a nomogram with good predictive ability to help clinicians evaluate the prognosis of patients.

Assessment of mortality-related risk factors and effective antimicrobial regimens for treatment of bloodstream infections caused by carbapenem-resistant Pseudomonas aeruginosa in patients with hematological diseases

Background

Infections caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) are related to higher mortality. The objective of this study was to explore clinical outcomes of CRPA bacteremia, identify risk factors and also, compare the efficacy of traditional and novel antibiotic regimens.

Methods

This retrospective study was conducted at a blood diseases hospital in China. The study included hematological patients who were diagnosed with CRPA bacteremia between January 2014 and August 2022. The primary endpoint was all-cause mortality at day 30. Secondary endpoints included 7-day and 30-day clinical cure. Multivariable Cox regression analysis was employed to identify mortality-related risk factors.

Results

100 patients infected with CRPA bacteremia were included and 29 patients accepted allogenic-hematopoietic stem cell transplantation. 24 received ceftazidime-avibactam (CAZ-AVI)-based therapy and 76 received other traditional antibiotics. 30-day mortality was 21.0%. Multivariable cox regression analysis showed neutropenia >7 days after bloodstream infections (BSI) (P=0.030, HR: 4.068, 95%CI: 1.146~14.434), higher Pitt bacteremia score (P<0.001, HR:1.824, 95%CI: 1.322~2.517), higher Charlson comorbidity index (P=0.01, HR: 1.613, 95%CI: 1.124~2.315) and bacteremia due to multidrug-resistant Pseudomonas aeruginosa (MDR-PA) (P=0.024, HR:3.086, 95%CI: 1.163~8.197) were identified as independent risk factors of 30-day mortality. After controlling for confounders, an additional multivariable cox regression analysis revealed definitive regimens containing CAZ-AVI were associated with lower mortality in CRPA bacteremia (P=0.016, HR: 0.150, 95%CI: 0.032~0.702), as well as in MDR-PA bacteremia (P=0.019, HR: 0.119, 95%CI: 0.020~0.709).

Conclusions

For patients with hematological diseases and CRPA bacteremia, 30-day mortality rate was 21.0% (21/100). Neutropenia >7 days after BSI, higher Pitt bacteremia score, higher Charlson comorbidity index and bacteremia due to MDR-PA increased 30-day mortality. CAZ-AVI-based regimens were effective alternatives for bacteremia due to CRPA or MDR-PA.

Anti-bacterial mechanism of baicalin-tobramycin combination on carbapenem-resistant Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa (P. aeruginosa) is an important cause of nosocomial infections, and contributes to high morbidity and mortality, especially in intensive care units. P. aeruginosa is considered a 'critical' category bacterial pathogen by the World Health Organization to encourage an urgent need for research and development of new antibiotics against its infections.

AIM

To investigate the effectiveness of baicalin combined with tobramycin therapy as a potential treatment method for carbapenem-resistant P. aeruginosa (CRPA) infections.

METHODS

Polymerase chain reaction (PCR) and RT-PCR were used to detect the expression levels of drug-resistant genes (including VIM, IMP and OprD2) and biofilm-related genes (including algD, pslA and lasR) in CRPA that confer resistance to tobramycin, baicalin and tobramycin combined with baicalin (0, 1/8, 1/4, 1/2 and 1MIC).

RESULTS

There was a correlation between biofilm formation and the expression of biofilm-related genes. In addition, VIM, IMP, OprD2, algD, pslA and lasR that confer biofilm production under different concentrations in CRPA were significantly correlated. The synergistic effect of baicalin combined with tobramycin was a significant down-regulation of VIM, IMP, algD, pslA and lasR.

CONCLUSION

Baicalin combined with tobramycin therapy can be an effective treatment method for patients with CRPA infection.

Risk factors and outcomes of inpatients with carbapenem-resistant Pseudomonas aeruginosa bloodstream infections in China: a 9-year trend and multicenter cohort study

Objective

Bacteremia caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) has high mortality, threatening the healthcare quality worldwide. Analysis is required to update the epidemiological data of CRPA bloodstream infections (BSI) and evaluate the prevalent strains in China. Moreover, it is necessary to clarify the risk factors associated with the development and mortality of CRPA bacteremia.

Methods

This is a 9-year multicenter retrospective study, enrolling 137 patients with CRPA BSI and 137 carbapenem-susceptible P. aeruginosa (CSPA) BSI during January 2012 and December 2020. Antimicrobials susceptibility between the two groups were compared. Risk factors of CRPA BSI were identified by binary logistic regression for development and cox regression for mortality. The Kaplan-Meier method was used to compare time to mortality. CRPA and difficult-to-treat resistant P. aeruginosa (DTRPA) detection rate was analyzed year-by-year in ZYH.

Results

A total of 7,384 P. aeruginosa clinical samples were cultured in ZYH during 9  years, and notable increase of CRPA and DTRPA detection rate in P. aeruginosa BSI was identified (from 17 to 60%; from 2.1 to 25%). Multivariate analysis revealed that prior ICU hospitalization, immunosuppressive therapy and exposure to carbapenems were independent risk factors for development of CRPA BSI. The 30-day crude mortality of 137 CRPA BSI was 39%. A total of 46 DTRPA were identified, and the 30-day mortality for patients infected by DTRPA was 50%. The 30-day crude mortality of CRPA BSI was independently associated with multiple organ failure and higher Pitt bacteremia score, whereas receipt appropriate therapy improved prognosis.

Conclusion

A significant increase in the detection rate of CRPA and DTRPA in P. aeruginosa BSI was identified. Strict policies for carbapenems usage, cautious decisions regarding the usage of immunosuppressive agent and standard care for patients with prior ICU hospitalization are necessary for CRPA BSI management.

Clinical outcomes of antimicrobial resistance in cancer patients: a systematic review of multivariable models

BACKGROUND

Infections are major causes of disease in cancer patients and pose a major obstacle to the success of cancer care. The global rise of antimicrobial resistance threatens to make these obstacles even greater and hinder continuing progress in cancer care. To prevent and handle such infections, better models of clinical outcomes building on current knowledge are needed. This internally funded systematic review (PROSPERO registration: CRD42021282769) aimed to review multivariable models of resistant infections/colonisations and corresponding mortality, what risk factors have been investigated, and with what methodological approaches.

METHODS

We employed two broad searches of antimicrobial resistance in cancer patients, using terms associated with antimicrobial resistance, in MEDLINE and Embase through Ovid, in addition to Cinahl through EBSCOhost and Web of Science Core Collection. Primary, observational studies in English from January 2015 to November 2021 on human cancer patients that explicitly modelled infection/colonisation or mortality associated with antimicrobial resistance in a multivariable model were included. We extracted data on the study populations and their malignancies, risk factors, microbial aetiology, and methods for variable selection, and assessed the risk of bias using the NHLBI Study Quality Assessment Tools.

RESULTS

Two searches yielded a total of 27,151 unique records, of which 144 studies were included after screening and reading. Of the outcomes studied, mortality was the most common (68/144, 47%). Forty-five per cent (65/144) of the studies focused on haemato-oncological patients, and 27% (39/144) studied several bacteria or fungi. Studies included a median of 200 patients and 46 events. One-hundred-and-three (72%) studies used a p-value-based variable selection. Studies included a median of seven variables in the final (and largest) model, which yielded a median of 7 events per variable. An in-depth example of vancomycin-resistant enterococci was reported.

CONCLUSIONS

We found the current research to be heterogeneous in the approaches to studying this topic. Methodological choices resulting in very diverse models made it difficult or even impossible to draw statistical inferences and summarise what risk factors were of clinical relevance. The development and adherence to more standardised protocols that build on existing literature are urgent.

Oral mucositis and microbial status in acute lymphoblastic leukemia subjects undergoing high-dose chemotherapy

Aim: To assess oral microbial status in patients with acute lymphoblastic leukemia (ALL) undergoing high-dose chemotherapy and to unravel possible associations between nosocomial pathogens and the establishment of chemotherapy-induced oral mucositis (CIOM). Methods: Oral mucosa, saliva, and peripheral blood samples were collected from 46 ALL subjects one day prior to chemotherapy (D0) and 2 weeks after treatment initiation (D14). Clinical intraoral inspection was performed by a single practitioner, with mucositis classification performed according to the WHO oral toxicity scale. Blood components were quantified by automatic flow cytometry, while oral Staphylococcus aureus and Pseudomonas aeruginosa were detected by Polymerase Chain Reaction with species-specific primers. Associations among bacteria and clinical findings were determined by Fisher’s Exact test, longitudinal bacterial changes by paired Macnemar, and correlations among blood parameters and mucositis status or bacteria via Mann-Whitney. Results: S. aureus displayed higher detection rates at D14 (p < 0.05) and was positively associated with mucositis, adoption of a non-solid diet (all p < 0.001), nausea and fever (all p < 0.05). Conversely, P. aeruginosa did not correlate to CIOM clinical parameters. At the systemic standpoint, lower hemoglobin levels associated with CIOM and fever events (all p < 0.01). Conclusion: The study evidences S. aureus as a potential pathogen in ALL-CIOM, reaffirming microbial control as an important preventive measure during high-dose immunosuppressive therapy. The weight of non-white-blood-cell parameters should be validated as novel CIOM biomarkers in prospective research.

Antimicrobial Therapy Duration for Bloodstream Infections Caused by Pseudomonas aeruginosa or Acinetobacter baumannii-calcoaceticus complex: A Retrospective Cohort Study

Background: Ideal therapy duration for Pseudomonas aeruginosa or Acinetobacter baumannii-calcoaceticus complex (ABC) bloodstream infections (BSI) is not defined, especially in the context of carbapenem resistance. In this study, we compared short- (≤7 days) and long-term (>7 days) antimicrobial therapy duration for these infections. Methods: We performed a retrospective cohort study in two tertiary-care hospitals in Porto Alegre, Brazil, from 2013 to 2019. Eligible patients aged ≥18 years were included and excluded for the following criteria: polymicrobial infections, treatment with non-susceptible antibiotics, complicated infections, or early mortality (<8 days of active antimicrobial therapy). The 30-day mortality risk was evaluated using a Cox regression model. Results: We included 237 BSI episodes, 51.5% caused by ABC and 48.5% by Pseudomonas aeruginosa. Short-term therapy was not associated with 30-day mortality, adjusted hazard ratio 1.01, 95% confidence interval 0.47–2.20, p = 0.98, when adjusted for Pitt score (p = 0.02), Charlson Comorbidity Index score (p < 0.01), and carbapenem resistance (p < 0.01). Among patients who survived, short-term therapy was associated with shorter hospital stay (p < 0.01). Results were maintained in the subgroups of BSI caused by carbapenem-resistant bacteria (p = 0.76), ABC (p = 0.61), and Pseudomonas aeruginosa (p = 0.39). Conclusions: Long-term therapies for non-complicated Pseudomonas aeruginosa and ABC BSI were not superior to short-term therapy for 30-day mortality.

Pseudomonas aeruginosa Bloodstream Infection, Resistance, and Mortality: Do Solid Organ Transplant Recipients Do Better or Worse?

BACKGROUND

The prevalence of antimicrobial resistance of Pseudomonas aeruginosa (P. aeruginosa) in solid organ transplant (SOT) recipients is higher than that of the general population. However, the literature supporting this statement is scarce. Identifying patients at risk of carbapenem resistance (CR) is of great importance, as CR strains more often receive inappropriate empiric antibiotic therapy, which is independently associated with mortality in bloodstream infections (BSIs).

METHODS

We prospectively recorded data from all consecutive BSIs from January 1991 to July 2019 using a routine purpose-designed surveillance database. The following variables were included: age, sex, type of transplant, use of vascular and urinary catheters, presence of neutropenia, period of diagnosis, treatment with steroids, origin of BSI, source of bacteremia, septic shock, ICU admission, mechanical ventilation, previous antibiotic treatment, treatment of bacteremia, and 30-day all-cause mortality.

RESULTS

We identified 2057 episodes of P. aeruginosa BSI. Of these, 265 (13%) episodes corresponded to SOT recipients (130 kidney transplants, 105 liver, 9 hearts, and 21 kidney-pancreas). Hematologic malignancy [OR 2.71 (95% CI 1.33-5.51), p = 0.006] and prior carbapenem therapy [OR 2.37 (95% CI 1.46-3.86), p < 0.001] were associated with a higher risk of having a CR P. aeruginosa BSI. Age [OR 1.03 (95% CI 1.02-1.04) p < 0.001], urinary catheter [OR 2.05 (95% CI 0.37-3.06), p < 0.001], shock at onset [OR 6.57 (95% CI 4.54-9.51) p < 0.001], high-risk source [OR 4.96 (95% CI 3.32-7.43) p < 0.001], and bacteremia caused by CR strains [OR 1.53 (95% CI 1.01-2.29) p = 0.036] were associated with increased mortality. Correct empirical therapy was protective [OR 0.52 (95% CI 0.35-0.75) p = 0.001]. Mortality at 30 days was higher in non-SOT patients (21% vs. 13%, p = 0.002). SOT was not associated with a higher risk of having a CR P. aeruginosa BSI or higher mortality.

CONCLUSIONS

In our cohort of 2057 patients with P. aeruginosa BSIs, hematologic malignancies and previous carbapenem therapy were independently associated with a risk of presenting CR P. aeruginosa BSI. Age, urinary catheter, high-risk source, bacteremia caused by carbapenem-resistant strains, and severity of the infection were independently associated with mortality, whereas correct empirical therapy was a protective factor. An increasing trend in the resistance of P. aeruginosa was found, with >30% of the isolates being resistant to carbapenems in the last period. SOT was not associated with a higher risk of carbapenem-resistant BSIs or higher mortality.

Carbapenem-resistant Pseudomonas aeruginosa infections in critically ill children: Prevalence, risk factors, and impact on outcome in a large tertiary pediatric hospital of China

Background and aims

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a major cause of healthcare-associated infections worldwide, but comprehensive study of clinical characteristics for CRPA infections among critically ill children remains limited in China. The objective of this study was to determine the epidemiology, risk factors, and clinical outcomes of CRPA infections among critically ill pediatric patients in a large tertiary pediatric hospital in China.

Methods

A retrospective case-control study of patients with P. aeruginosa infections was conducted in the three intensive care units (ICUs) of Shanghai Children's Medical Center from January 2016 to December 2021. All patients with CRPA infection in the ICUs were enrolled as case patients. Patients with carbapenem-susceptible P. aeruginosa (CSPA) infection were randomly selected as control patients in a ratio of 1:1. Clinical characteristics of those inpatients were reviewed through the hospital information system. Univariate and multivariate analyses were performed to evaluate risk factors associated with the development of CRPA infections and mortality of P. aeruginosa infections.

Results

A total of 528 cases of P. aeruginosa infection in the ICUs were enrolled in the 6-year study. The prevalence of CRPA and MDRPA (multidrug-resistance P. aeruginosa) was 18.4 and 25.6%, respectively. Significant risk factors related to CRPA infection were the length of hospitalization >28 days (OR = 3.241, 95% CI 1.622-6.473, p = 0.001), receiving invasive operations (OR = 2.393, 95% CI 1.196-4.788, p = 0.014) and a blood transfusion (OR = 7.003, 95% CI 2.416-20.297, p < 0.001) within 30 days before infection. Conversely, birth weight ≥2,500 g (OR = 0.278, 95% CI 0.122-0.635, p = 0.001) and breast nursing (OR = 0.362, 95% CI 0.168-0.777, p = 0.009) were significant protective factors against CRPA infections. The in-hospital mortality rate was 14.2%, and no difference in mortality was observed between patients with CRPA and CSPA infections. Platelet < 100 × 10⁹/L (OR = 5.729, 95% CI 1.048-31.308, p = 0.044) and serum urea <3.2 mmol/L (OR = 5.173, 95% CI 1.215-22.023, p = 0.026) were independent predictors for the mortality due to P. aeruginosa infection.

Conclusions

Our findings provide insights into CRPA infections among critically ill children in China. They provide guidance in identifying patients that may be at high risk for a resistant infection and emphasize the importance of antimicrobial stewardship and infection control in hospitals.

Risk Factors and Outcomes of Patients with Carbapenem-Resistant Pseudomonas aeruginosa Bloodstream Infection

Purpose

The rising incidence of carbapenem-resistant Pseudomonas aeruginosa (PA) bloodstream infection (BSI) has made the selection of antibiotic therapy more difficult and caused high mortality. This study was aimed at exploring the risk factors for carbapenem-resistant Pseudomonas aeruginosa (CRPA) bloodstream infection and identifying the risk factors for the outcomes of patients with PA-BSI.

Methods

We performed a retrospective cohort study of patients with PA-BSI in a tertiary hospital from January 2017 to December 2021 in China. Epidemiological, clinical, and microbiological characteristics were described. Risk factors for CRPA-BSI and the outcomes of PA-BSI inpatients were identified, using multivariate logistic regression analysis.

Results

A total of 198 PA-BSI inpatients were included. The negative outcome rate was significantly higher in patients infected with CRPA (15/34, 44.12%) than with carbapenem-susceptible Pseudomonas aeruginosa (CSPA) (35/164, 21.34%), and the difference was statistically significant (P=0.005). Multivariate logistic regression analysis showed that previous exposure to carbapenem (OR 3.519, 95% CI 1.359-9.110, P=0.010) was an independent risk factor for CRPA-BSI. In addition, CRPA (OR 1.615, 95% CI 0.626-4.171, P=0.32) was not an independent risk factor for negative outcome among PA-BSI inpatients.

Conclusion

Our study showed that previous exposure to carbapenem was an independent risk factor for CRPA-BSI. CRPA was not an independent risk factor for a negative outcome in PA-BSI inpatients.

Development and validation of nomograms for predicting the risk probability of carbapenem resistance and 28-day all-cause mortality in gram-negative bacteremia among patients with hematological diseases

Objectives

Gram-negative bacteria (GNB) bloodstream infections (BSIs) are the most widespread and serious complications in hospitalized patients with hematological diseases. The emergence and prevalence of carbapenem-resistant (CR) pathogens has developed into a considerable challenge in clinical practice. Currently, nomograms have been extensively applied in the field of medicine to facilitate clinical diagnosis and treatment. The purpose of this study was to explore risk indicators predicting mortality and carbapenem resistance in hematological (HM) patients with GNB BSI and to construct two nomograms to achieve personalized prediction.

Methods

A single-center retrospective case-control study enrolled 244 hospitalized HM patients with GNB-BSI from January 2015 to December 2019. The least absolute shrinkage and selection operator (LASSO) regression analysis and multivariate logistic regression analysis were conducted to select potential characteristic predictors of plotting nomograms. Subsequently, to evaluate the prediction performance of the models, the prediction models were internally validated using the bootstrap approach (resampling = 1000) and 10-fold cross validation.

Results

Of all 244 eligible patients with BSI attributed to GNB in this study, 77 (31.6%) were resistant to carbapenems. The rate of carbapenem resistance exhibited a growing tendency year by year, from 20.4% in 2015 to 42.6% in 2019 (p = 0.004). The carbapenem resistance nomogram constructed with the parameters of hypoproteinemia, duration of neutropenia ≥ 6 days, previous exposure to carbapenems, and previous exposure to cephalosporin/β-lactamase inhibitors indicated a favorable discrimination ability with a modified concordance index (C-index) of 0.788 and 0.781 in both the bootstrapping and 10-fold cross validation procedures. The 28-day all-cause mortality was 28.3% (68/240). The prognosis nomogram plotted with the variables of hypoproteinemia, septic shock, isolation of CR-GNB, and the incomplete remission status of underlying diseases showed a superior discriminative ability of poorer clinical prognosis. The modified C-index of the prognosis nomogram was 0.873 with bootstrapping and 0.887 with 10-fold cross validation. The decision curve analysis (DCA) for two nomogram models both demonstrated better clinical practicality.

Conclusions

For clinicians, nomogram models were effective individualized risk prediction tools to facilitate the early identification of HM patients with GNB BSI at high risk of mortality and carbapenem resistance.

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.

Better Outcome of Off-Label High-Dose Ceftazidime in Hemato-Oncological Patients with Infections Caused by Extensively Drug-Resistant Pseudomonas Aeruginosa

Background

P. aeruginosa sepsis in immunocompromised patients is a serious complication of cancer treatment, especially in the case of an Extensively Drug Resistant (XDR) pathogen. The aim of the study is to evaluate the efficacy of high-dose ceftazidime in the treatment of XDR P. aeruginosa infection and to compare it with the conventionally treated cohort in hemato-oncological patients.

Methods

We identified 27 patients with XDR P. aeruginosa infection during the 2008-2018 period, 16 patients served as a conventionally treated cohort with an antipseudomonal beta-lactam antibiotic in standard dose (cohort A), and 11 patients were treated with high-dose ceftazidime (cohort B). Most of the patients were neutropenic and under active treatment for their cancer in both cohorts.

Results

Mortality and related mortality were statistically significantly better for cohort B than cohort A; it was 18.2% and 9.1% for cohort B and 68.8% and 68.8% for cohort A, respectively. More patients in cohort A needed mechanical ventilation and renal replacement therapy, 75% and 50% for cohort A and 27.3% and 9.9% for cohort B, respectively. It corresponded well with the worst sequential organ failure score (SOFA) in cohort A compared to cohort B, 16 versus 7, respectively. Reversible neurotoxicity was seen only in two patients in cohort B.

Conclusion

Ceftazidime in high doses is a very potent antibiotic (ATB) for treating XDR P. aeruginosa infections in neutropenic cancer with acceptable toxicity.

Pseudomonas aeruginosa Infections in Cancer Patients

Pseudomonas aeruginosa (P. aeruginosa) is one of the most frequent opportunistic microorganisms causing infections in oncological patients, especially those with neutropenia. Through its ability to adapt to difficult environmental conditions and high intrinsic resistance to antibiotics, it successfully adapts and survives in the hospital environment, causing sporadic infections and outbreaks. It produces a variety of virulence factors that damage host cells, evade host immune responses, and permit colonization and infections of hospitalized patients, who usually develop blood stream, respiratory, urinary tract and skin infections. The wide intrinsic and the increasing acquired resistance of P. aeruginosa to antibiotics make the treatment of infections caused by this microorganism a growing challenge. Although novel antibiotics expand the arsenal of antipseudomonal drugs, they do not show activity against all strains, e.g., MBL (metalo-β-lactamase) producers. Moreover, resistance to novel antibiotics has already emerged. Consequently, preventive methods such as limiting the transmission of resistant strains, active surveillance screening for MDR (multidrug-resistant) strains colonization, microbiological diagnostics, antimicrobial stewardship and antibiotic prophylaxis are of particular importance in cancer patients. Unfortunately, surveillance screening in the case of P. aeruginosa is not highly effective, and a fluoroquinolone prophylaxis in the era of increasing resistance to antibiotics is controversial.

The Threat of Carbapenem-Resistant Gram-Negative Bacteria in Patients with Hematological Malignancies: Unignorable Respiratory Non-Fermentative Bacteria-Derived Bloodstream Infections

Background

Carbapenem-resistant Gram-negative bacteria (CRGNB) bloodstream infection (BSI) pose a significant threat to the prognosis of hematologic malignancies (HM) patients. Understanding the distribution of pathogenic bacteria, changes in carbapenem-resistant trends, risk factors for CRGNB infections, and exploring the early detection measures can help reduce mortality.

Methods

We conducted a multicenter retrospective study of Gram-negative bacteria (GNB) BSI in patients with HM in three university-affiliated hospitals in Hunan Province, China, from January 2010 to December 2020. Demographic and clinical data were collected from the hospital electronic medical records system.

Results

CRGNB caused 138 (15.3%) of 902 GNB BSI. The detection rate of CRGNB increased from 6.4% in 2010–2012 to 35.4% in 2019–2020. The 7-day mortality rate was significantly higher in patients with CRGNB BSI than in patients with carbapenem-susceptible Gram-negative bacteria (CSGNB) BSI [31.9% (44/138) vs 9.7% (74/764), P < 0.001], and the mortality rate in patients with carbapenem-resistant non-fermenting bacteria (CRNFB) bloodstream infections was generally higher than that of carbapenem-resistant Enterobacteriaceae (CRE). Urinary catheter (OR, 2.814; CI=1.395–5.680; P=0.004) and prior exposure to carbapenem (OR, 4.372; CI=2.881–6.635; P<0.001) were independent risk factors for CRGNB BSI. Analysis of co-infections showed that 50%–85% of patients with CRGNB BSI had pulmonary infections, sputum culture results suggested that sputum culture positivity rate was as high as 57.1%–66.7% in patients with carbapenem-resistant Acinetobacter baumannii (CRAB) and Stenotrophomonas maltophilia BSI, and the results of antimicrobial susceptibility testing of sputum cultures were consistent with the blood cultures.

Conclusion

Carbapenem resistance has dramatically increased in HM patients with GNB BSI in recent years and is associated with a worse outcome, especially for non-fermenting bacteria. In high-risk patients, early screening of the respiratory tract specimens may help to detect CRNFB colonization and protect patients from breakthrough BSI.

Predictors of multidrug resistant Pseudomonas aeruginosa involvement in bloodstream infections

PURPOSE OF REVIEW

In the last decades, there has been a worldwide worrisome spread of multidrug resistant (MDR) Pseudomonas aeruginosa. Treatment of these infections is challenging, in part due to the lack of therapeutic options, and the importance of prescribing an adequate empirical treatment. Bacteraemia is one of the most severe infections, with mortality rates ranging between 20 and 40%.

RECENT FINDINGS

It is key to understand which patients are at a higher risk of MDR P. aeruginosa bloodstream infection (BSI) to better direct empirical therapies and improve overall survival. Immunocompromised patients are among the most vulnerable for the worst outcomes. Environmental exposure, integrity of the microbiota, and host immunity are the key determinants for the initial colonization and expansion on mucosal surfaces and potential invasion afterwards by MDR P. aeruginosa.

SUMMARY

Available data suggest that high colonization pressure (settings with high prevalence like intensive care units), disruption of healthy microbiota (prior use of antibiotics, in particular fluoroquinolones), immunosuppression (neutropenia) and breaking natural barriers (venous or urine catheters), are the main risk factors for MDR P. aeruginosa BSI.

Antibiotic resistance in the patient with cancer: Escalating challenges and paths forward

Infection is the second leading cause of death in patients with cancer. Loss of efficacy in antibiotics due to antibiotic resistance in bacteria is an urgent threat against the continuing success of cancer therapy. In this review, the authors focus on recent updates on the impact of antibiotic resistance in the cancer setting, particularly on the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.). This review highlights the health and financial impact of antibiotic resistance in patients with cancer. Furthermore, the authors recommend measures to control the emergence of antibiotic resistance, highlighting the risk factors associated with cancer care. A lack of data in the etiology of infections, specifically in oncology patients in United States, is identified as a concern, and the authors advocate for a centralized and specialized surveillance system for patients with cancer to predict and prevent the emergence of antibiotic resistance. Finding better ways to predict, prevent, and treat antibiotic-resistant infections will have a major positive impact on the care of those with cancer.

Gram-Negative Bacteria Bloodstream Infections in Patients with Hematological Malignancies - The Impact of Pathogen Type and Patterns of Antibiotic Resistance: A Retrospective Cohort Study

Background

Enterobacteriaceae (EB) and non-fermentative bacteria (NFB) are the main pathogens responsible for gram-negative bloodstream infections (GN-BSI) in patients with hematological malignancies (HMs). These two pathogen types have heterogeneous resistance mechanisms to antibiotics. However, the impact of pathogen species and pattern of antibiotic resistance on the outcomes of patients with HMs remains unclear.

Methods

We retrospectively collected clinical data of patients with HMs at three comprehensive hospitals in Hunan Province, China, between January 2010 and May 2018. The data analyzed the impact that different species and patterns of antibiotic resistance had on the outcome of patients with HMs.

Results

The majority of the 835 monomicrobial isolates collected from patients with HMs and GN-BSIs were Enterobacteriaceae (75.7%). While detections of MDR pathogens in BSIs as a whole are decreasing, sub-analysis shows that detections of extended spectrum β-lactamase-producing (ESBL) Enterobacteriaceae and carbapenem-resistant pathogens in BISs are rising. Comparing different species, the early mortality rate associated with infections caused by NFB was significantly higher than infections caused by Enterobacteriaceae (22.6% vs 9.7%, p < 0.001). Across different multidrug-resistant (MDR) patterns, ESBL bacteria did not have a significant impact on health outcomes. Carbapenem-resistant bacteria, on the other hand, were observed to significantly affect early mortality rate, such as carbapenem-resistant Klebsiella pneumoniae (36.0% vs 7.6%, P < 0.001) and carbapenem-resistant non-fermentative bacteria (44.7% vs 16.5%, P < 0.001).

Conclusion

Our findings suggest that both species and patterns of antibiotic resistance can affect the early mortality of patients with HMs during BSI.