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

Pathogenic spectrum and drug resistance of bloodstream infection in patients with acute myeloid leukaemia: a single centre retrospective study

Background

Bloodstream infection (BSI) represent a prevalent complication in haematological malignancies (HMs). Typically, Patients with BSI usually undergo empirical treatment pending pathogen identification. The timely and effective management of BSIs significantly influences patient prognosis. However, pathogen distribution in BSIs exhibits regional variation. In this study, we investigated the clinical characteristics, pathogen spectrum, drug resistance, risk factors of short-term prognosis and long-term prognostic factors of acute myeloid leukemia (AML) patients with BSI at Zhejiang Provincal People's Hospital.

Methods

From 2019 to 2021, a total of 56 AML patients with BSI were treated in the Department of Haematology at Zhejiang Province People's Hospital. Data regarding pathogen spectrum and drug resistance were collected for analysis. The patients were stratified into non-survivor cohort and survivor cohort within 30 days after BSI, and the predictors of 30-days mortality were identified through both univariate and multivariate Logistic regression analyses. Furthermore, Kaplan-Meier survival analysis and Cox regression analysis were employed to ascertain the risk factors associated with poor prognosis in AML patients complicated by BSI.

Results

A total of 70 strains of pathogenic bacteria were isolated from 56 AML patients with BSI. Gram-negative bacteria constituted the predominant pathogens (71.4%), with Klebsiella pneumoniae being the most prevalent (22.9%). Gram-positive bacteria and fungi accounted for 22.9% and 5.7%, respectively. Univariate and multivariate analyses revealed significant differences in total protein, albumin levels, and the presence of septic shock between the non-survivor cohort and the survior cohort 30 days post-BSI. COX regression analysis showed that agranulocytosis duration exceeding 20 days (HR:3.854; 95% CI: 1.451-10.242) and septic shock (HR:3.788; 95% CI: 1.729-8.299) were independent risk factors for poor prognosis in AML patients complicated by BSI. Notably, the mortality rate within 30 days after Stenotrophomonas maltophilia infection was up to 71.4%.

Conclusions

In this study, Gram-negative bacteria, predominantly Klebsiella pneumoniae, constituted the primary pathogens among AML patients with BSIs. Serum albumin levels and the presence of septic shock emerged as independent risk factors for mortality within 30 days among AML patients with BSI. In terms of long-term prognosis, extended agranulocytosis duration exceeding 20 days and septic shock were associated with elevated mortality rates in AML patients with BSI. Additionally, in our centre, Stenotrophomonas maltophilia infection was found to be associated with a poor prognosis. Early intervention for Stenotrophomonas maltophilia infection in our centre could potentially improve patient outcomes.

Outcomes of 23 patients diagnosed with New Delhi metallo-beta-lactamase (NDM)-producing Klebsiella pneumoniae infection treated with ceftazidime/avibactam and aztreonam at a single center in Poland

PURPOSE

Amongst all etiologic hospital-acquired infection factors, K. pneumoniae strains producing New Delhi metallo-β-lactamase (KP-NDM) belong to pathogens with the most effective antibiotic resistance mechanisms. Clinical guidelines recommend using ceftazidime/avibactam with aztreonam (CZA + AT) as the preferred option for NDM-producing Enterobacterales. However, the number of observations on such treatment regimen is limited. This retrospective study reports the clinical and microbiological outcomes of 23 patients with KP-NDM hospital-acquired infection treated with CZA + AT at a single center in Poland.

METHODS

The isolates were derived from the urine, lungs, blood, peritoneal cavity, wounds, and peritonsillar abscess. In microbiological analysis, mass spectrometry for pathogen identification, polymerase chain reaction, or an immunochromatographic assay for detection of carbapenemase, as well as VITEK-2 system, broth microdilution, and microdilution in agar method for antimicrobial susceptibility tests were used, depending of the pathogens' nature. CZA was administered intravenously (IV) at 2.5 g every eight hours in patients with normal kidney function, and aztreonam was administered at 2 g every eight hours IV. Such dosage was modified when renal function was reduced.

RESULTS

KP-NDM was eradicated in all cases. Four patients (17.4%) died: three of them had a neoplastic disease, and one - a COVID-19 infection.

CONCLUSION

The combination of CZA + AT is a safe and effective therapy for infections caused by KP-NDM, both at the clinical and microbiological levels. The synergistic action of all compounds resulted in a good agreement between the clinical efficacy of CZA + AT and the results of in vitro susceptibility testing.

Ceftazidime-avibactam and aztreonam combination for Carbapenem-resistant Enterobacterales bloodstream infections with presumed Metallo-β-lactamase production: a systematic review and meta-analysis

INTRODUCTION

Carbapenem-resistant Enterobacterales (CRE) due to Metallo-β-lactamase (MBL) production are treated with either polymyxins or the novel combination of ceftazidime-avibactam and aztreonam (AA). This study aims to evaluate the 30-day mortality of AA in patients with BSI caused by MBL-CRE infections.

METHODOLOGY

In this systematic review and meta-analysis, all articles up to June 2023 were screened using search terms like 'CRE', 'MBL', 'AA' and 'polymyxins'. The risk ratio for AA vs polymyxins was pooled using a random-effect model, and the results were represented by a point estimate with a 95% confidence interval.

RESULTS

After removing the duplicates, the titles and abstracts of 455 articles were screened, followed by a full-text screening of 50 articles. A total of 24 articles were included for systematic review, and four comparative studies were included in the meta-analysis. All four studies had a moderate or serious risk of bias. The pooled risk ratio for 30-day mortality for AA vs. polymyxins was 0.51 (95%CI: 0.34-0.76), p < 0.001. There was no significant heterogeneity.

CONCLUSION

The meta-analysis from studies with a high risk of bias shows that AA is associated with lesser 30-day mortality when compared to polymyxins in patients with MBL-producing CRE BSI. Registration with PROSPERO- CRD42023433608.