Bloodstream and central line isolates from hematopoietic stem cell transplant recipients: data from a developing country

Staphylococcus epidermidis alters macrophage polarization and phagocytic uptake by extracellular DNA release in vitro

Biofilm formation shields Staphylococcus epidermidis from host defense mechanisms, contributing to chronic implant infections. Using wild-type S. epidermidis 1457, a PIA-negative mutant (1457-M10), and an eDNA-negative mutant (1457ΔatlE), this study examined the influence of biofilm matrix components on human monocyte-derived macrophage (hMDM) interactions. The wild-type strain was resistant to phagocytosis and induced an anti-inflammatory response in hMDMs, while both mutants were more susceptible to phagocytosis and triggered a pro-inflammatory response. Removing eDNA from the 1457 biofilm matrix increased hMDM uptake and a pro-inflammatory reaction, whereas adding eDNA to the 1457ΔatlE mutant reduced phagocytosis and promoted an anti-inflammatory response. Inhibiting TLR9 enhanced bacterial uptake and induced a pro-inflammatory response in hMDMs exposed to wild-type S. epidermidis. This study highlights the critical role of eDNA in immune evasion and the central role of TLR9 in modulating macrophage responses, advancing the understanding of implant infections.

Seasonal Characterization of the Aerobiome in Hematopoietic Stem Cell Transplant Rooms: Potential Risk for Immunosuppressed Patients

Infections pose a risk for patients undergoing hematopoietic stem cell (HSC) transplants due to their immunosuppression, making them susceptible to opportunistic infections. Therefore, understanding the composition of the aerobiome in this area is vital. The aim of this study was to characterize the aerobiome in an HSC transplant area, evaluating the impact of infrastructure and health personnel operations on air contamination. The environmental parameters and aerobiome of the HSC transplant area at Hospital Juárez de México were quantified over one year. Finally, a double-entry Vester matrix was constructed to classify problems according to their degree of causality. The abundance and taxonomic diversity of the aerobiome were dependent on seasonality, environmental factors, and high-efficiency filtration. Gram-positive bacteria predominated, followed by fungi and Gram-negative bacteria. ANOVA revealed significant differences in the bacterial aerobiome but not in the fungal aerobiome among the transplant rooms. Clinically, fungi such as Aspergillus fumigatus, Alternaria spp., Cladosporium spp., and Penicillium spp. were identified. ESKAPE bacteria typing revealed clonal dispersion. Finally, the Vester matrix highlighted critical problems associated with contamination due to the absence of HEPA filtration and non-adherence in patient management practices. HEPA filtration and positive pressure are essential to improve the air quality and reduce the microbiological load. However, the control areas will depend on patient management and routine activities, such as entry protocols in controlled areas.

A review of the epidemiology of invasive fungal infections in Asian patients with hematological malignancies (2011-2021)

The incidence of invasive fungal infection (IFI) is increasing, especially among patients diagnosed with hematological malignancies due to their immunocompromised nature. Other risk factors include advanced age, exposure to immunosuppressants, neutropenia, and catheter use. Some of the most common IFI organisms reported are Candida and Aspergillus species, and other fungal species, including Scedosporium, Trichosporon, Cryptococcus, and Fusarium have also increasingly been reported in the past years. However, the epidemiologic data on IFI among patients with hematological malignancies in Asian countries are lacking. Therefore, we investigated published epidemiologic data on such cases from the past 10 years (2011-2021) and discuss the challenges faced in the diagnosis and management of IFIs in Asia.

Epidemiologic and microbiologic evaluation of catheter-line bloodstream infection in a pediatric hematopoietic stem cell transplant center

BACKGROUND

Children who underwent hematopoietic stem cell transplant (HSCT) transplants are at high risk of developing central-line-associated bloodstream infections (CLABSIs). The present study aimed to identify possible risk factors for mortality by analyzing the clinical and laboratory characteristics of patients diagnosed with CLABSI in our pediatric hematopoietic stem cell transplant unit.

METHODS

The initial CLABSI episodes of 102 children were analyzed. Medical records of the patients were evaluated by preformed standardized surveys. Univariate analysis and multivariate logistic regression analysis were performed to identify risk factors for mortality.

RESULTS

Thirty-five patients (34.3%) were female. The median age was 48 months (3-204). The median time to onset of CLABSI was 19 days (4-150). The gram-negative and gram-positive bacteria ratio among the causative agents was 57.8% to 34.3%. The mortality rate was 12.6%. The presence of severe neutropenia, initiation of inappropriate empirical antibiotic therapy, the presence of hypotension, persistent bacteremia, pediatric intensive care unit admission, growth of carbapenemase-positive gram-negative microorganism and multidrug-resistant bacteria were significantly high in the mortality group when compared to survivors. The presence of hypotension, inappropriate empirical antibiotic therapy, and persistent bacteremia were found to be independent risk factors for mortality.

CONCLUSIONS

Rational use of antibiotics, active surveillance and screening of patients together with improved infection control practices may reduce the incidence and the consequences of CLABSIs.

Bacteremia in Hematopoietic Stem Cell Recipients Receiving Fluoroquinolone Prophylaxis: Incidence, Resistance, and Risk Factors

Background

Bacteremia is a common complication in hematopoietic stem cell transplant (HSCT) recipients. Prophylactic fluoroquinolone is recommended and used in these individuals. Breakthrough infections can occur with fluoroquinolone-resistant strains. We aimed to identify the incidence, resistance, and risk factors for bacteremia in HSCT recipients receiving fluoroquinolone prophylaxis.

Materials and Methods

This retrospective study was performed on patients who received fluoroquinolone prophylaxis and underwent autologous and allogeneic HSCT between 2015 and 2019. The incidence of bacteremia, comorbidity, treatment, and invasive procedures was compared in these patients with and without bacteremia.

Results

There were 553 patients included in the study, 68 (12.3%) had bacteremia. The incidence of bacteremia is 8.2% of autologous HSCT recipients and 18.4% of allogeneic HSCT recipients. The significant risk factors associated with bacteremia were steroid-using (odds ratio [OR]:13.83, 95% confidence interval [CI]: 2.88 - 66.40), higher Charlson Comorbidity Index (CCI)-mean (OR: 1.57, 95% CI: 1.15 - 2.16), diabetes mellitus (OR: 4.29, 95% CI: 1.11 - 16.48) in autologous HSCT, steroid-using (OR: 6.84, 95% CI: 1.44 - 32.33), longer duration of neutropenia (OR: 1.05, 95% CI: 1.01 - 1.09) using central venous catheter (OR: 7.81, 95% CI: 1.00 - 61.23) in allogeneic HSCT. Seventy-three pathogens were isolated from a total of 68 bacteremia episodes. The most commonly occurring agents were Escherichia coli, Klebsiella pneumoniae and Enterococcus spp. Resistance to fluoroquinolones was 87.2%, 70.0% and 60.0% among these strains, respectively.

Conclusion

High CCI, diabetes mellitus, use of steroids and long-term neutropenia and use of central venous catheters were significantly associated with the breakthrough bacteremia in HSCT recipients receiving fluoroquinolone prophylaxis. Fluoroquinolone prophylaxis may reduce the incidence of bacteremia but may select strains resistant to fluoroquinolone.

Infections in hematopoietic stem cell transplant patients admitted to Hematology intensive care unit: a single-center study

OBJECTIVE

The aim of this study was to investigate the data of HSCT patients who were admitted to our Hematology ICU due to infections or infectious complications.

MATERIALS AND METHODS

HSCT patients who were admitted to our Hematology ICU between 01 January 2014 and 01 September 2017 were analyzed retrospectively.

RESULTS

62 HSCT patients were included in this study. The median age was 55.5 years and 58% of the patients were allogeneic HSCT patients. Major underlying hematologic disorders were multiple myeloma (29%) and lymphoma (27.4%). The most common reasons for ICU admission were sepsis/septic shock (61.3%) and acute respiratory failure (54.8%). Overall ICU mortality rate was 45.2%. However, a lot of factors were related with ICU mortality of HSCT patients in univariate analysis, only APACHE II score was found to be an independent risk factor for ICU mortality. While there was infection in 58 patients at ICU admission, new infections developed in 38 patients during ICU stay. The most common new infection was pneumonia/VAP, while the most frequently isolated bacteria were Acinetobacter baumannii. Length of ICU stay, sepsis/septic shock as a reason for ICU admission and the presence of urinary catheter at ICU admission were determined factors for ICU-acquired infections. There was no difference between autologous and allogeneic stem cell transplant patients in terms of ICU morbidities and mortality. However, pneumonia/VAP developed in the ICU was higher in autologous HSCT patients, while bloodstream/catheter-related bloodstream infection was higher in allogeneic HSCT patients.

CONCLUSION

It was concluded that early or late post-HSCT infections and related complications (sepsis, organ failure, etc.) constituted a major part of the reasons for ICU admission, ICU mortality and ICU morbidities.

Early bacterial and fungal infection in children receiving allogeneic stem cell transplantation for acute lymphoblastic leukemia in Argentina

Infections are important complications associated with allogeneic HSCT. Describing infection rates in low- and middle-income countries provides data to infer efficacy of supportive care practices in these settings. In this retrospective cohort study, we included patients (age ≤ 18 years) who underwent a first allogeneic HSCT for ALL in a single center in Argentina between 1998 and 2016. The primary outcome was sterile site bacterial infection. Secondary outcomes were proven or probable invasive fungal infection, TRM, and infectious deaths. There were 68 allogeneic HSCT recipients with ALL included in this analysis. Overall, 17 (25.0%) experienced at least one sterile site bacterial infection and 10 (14.7%) experienced at least one proven or probable invasive fungal infection. The TRM rate was 19.1%, and 3 (4.4%) patients died of infection. In a middle-income country center in Argentina, pediatric allogeneic HSCT infection rates, TRM, and infection-related mortality were comparable to high-income countries. These data support continuation of allogeneic HSCT programs in similar resource-limited settings provided that adequate supportive care and monitoring of outcomes can be performed.

Epidemiology of bloodstream infections after myeloablative and non-myeloablative allogeneic hematopoietic stem cell transplantation: A single-center cohort study

BACKGROUND

Patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT) often develop bloodstream infections (BSI). We aimed to describe the etiologies and antibiotic resistance patterns of BSI after allo-HSCT, and, as knowledge about the impact of conditioning regimen is limited, we looked at the incidence, timing, risk factors, and mortality of BSI separately for myeloablative (MA)- and non-myeloablative (NMA)-conditioned patients.

METHODS

All 460 patients (207 MA- and 253 NMA-conditioned) who underwent their first allo-HSCT at our center from 2008 to 2013 were included in a historical cohort. BSI were registered from initiation of conditioning to day 360 after transplantation.

RESULTS

BSI occurred in 34% (95% confidence interval [CI]: 28%, 41%) of MA-conditioned patients and in 17% (95% CI: 12%, 22%) of NMA-conditioned patients. Of all isolates, 68% were gram-positive bacteria (GPB), 23% gram-negative bacteria (GNB), and 9% fungi. The GPB/GNB ratio declined from 2008 to 2014 (P for trend <.01). Of all GNB, 47% were multidrug resistant (MDR), but the proportion declined over the study period. In a multivariate Cox regression model, only acute graft-versus-host disease was associated with a higher hazard of first BSI (hazard ratio 2.50, 95% CI: 1.48, 4.21). Overall 30-day survival after a BSI was higher for MA-conditioned patients than for NMA-conditioned patients (89% vs 74%, P=.04).

CONCLUSION

MA-conditioned patients experience BSI more often than NMA-conditioned patients in the year after allo-HSCT. While BSI are increasingly caused by GNB, the rate of MDR GNB is declining.

Infectious complications in children with acute lymphoblastic leukemia treated in low-middle-income countries

Infections are the most important cause of morbidity and mortality in children treated for acute lymphoblastic leukemia (ALL). The rates of infection-associated mortality are up to 10-times higher in low- and middle-income countries (LMIC) than in high-income countries. The prevention, early recognition and management of infectious complications is especially challenging in LMIC because of disease and poverty-related factors, as well as the shortage of trained personnel, supplies, diagnostic tools and adequate organizational infrastructure. Children in LMIC with ALL, who are frequently underweight, are at increased risk of community-acquired pathogens, nosocomial multidrug-resistant pathogens and opportunistic microorganisms. This review summarizes the challenges of managing the major categories of infections in children receiving treatment for ALL and provides updated practical recommendations for preventing and managing these infections in LMIC.

The Changing Epidemiology of Bloodstream Infections and Resistance in Hematopoietic Stem Cell Transplantation Recipients

OBJECTIVE

Patients receiving hematopoietic stem cell transplantation (HSCT) are exposed to highly immunosuppressive conditions and bloodstream infections (BSIs) are one of the most common major complications within this period. Our aim, in this study, was to evaluate the epidemiology of BSIs in these patients retrospectively.

MATERIALS AND METHODS

The epidemiological properties of 312 patients with HSCT were retrospectively evaluated.

RESULTS

A total of 312 patients, followed between 2000 and 2011, who underwent autologous (62%) and allogeneic (38%) HSCT were included in the study. The most common underlying malignancies were multiple myeloma (28%) and Hodgkin lymphoma (21.5%). A total of 142 (45%) patients developed at least 1 episode of BSI and 193 separate pathogens were isolated from the blood cultures. There was a trend of increase in the numbers of BSIs in 2005-2008 and a relative increase in the proportion of gram-positive infections in recent years (2009-2011), and central venous catheter-related BSI was found to be most common source. Coagulase-negative staphylococci (49.2%) and Acinetobacter baumannii (8.8%) were the most common pathogens. Extended-spectrum beta-lactamase-producing strains were 23% and 22% among Escherichia coli and Klebsiella spp. isolates, respectively. Quinolone resistance was detected in 10% of Enterobacteriaceae. Resistance to carbapenems was not detected in Enterobacteriaceae, while it was seen at 11.1% and 23.5% in Pseudomonas and Acinetobacter strains, respectively.

CONCLUSION

A shift was detected from gram-negative bacteria to gram-positive in the etiology over the years and central lines were the most common sources of BSIs.