Microbial translocation contribute to febrile episodes in adults with chemotherapy-induced neutropenia

Alarming Upward Trend in Multidrug-Resistant Bacteria in a Large Cohort of Immunocompromised Children: A Four-Year Comparative Study

Documenting bacteremia at the onset of fever in immunosuppressed children is challenging; therefore, it leads to the early administration of broad-spectrum antibiotics. We aimed to analyse the evolution of antibiotic resistance profiles of bacterial bloodstream infections (BSI) and gut colonisations in a large cohort of immunocompromised children carrying a central venous catheter, in comparison with a prior, similar study conducted in our centre from 2014 to 2017. A retrospective, observational cohort study was conducted from January 2018 to December 2021, in a tertiary centre for paediatric immuno-haematology and oncology. Empirical antibiotic therapy was adapted to the immunosuppression risk group and prior bacterial colonisation. There was a mean of 6.9 BSI/1000 patient bed days. Multidrug-resistant bacteria (MDRB) associated BSI accounted for 35/273 (12.8%). The incidence of MDRB gum/gut colonisation and MDRB associated BSI increased annually and correlated with the level of immunosuppression (p = 0.024). One third (34.7%) of the BSI episodes were not associated with neutropenia. As compared to the previous study, an alarming emergence of MDRB responsible for gut colonisations and BSI in immunosuppressed children was reported over the last four years. The degree of immunosuppression directly correlates with the risk of having an MDRB gut colonisation or MDRB BSI.

Bacterial Translocation in Gastrointestinal Cancers and Cancer Treatment

In recent years, there has been increasing evidence that gut microbiota is associated with the onset and exacerbation of various diseases, such as gastrointestinal cancer. For instance, it is well known that local inflammation of the intestinal tract in colorectal cancer that is caused by the increased number of Fusobacterium, due to changes in the intestinal bacterial flora, is involved in carcinogenesis. In contrast, gut bacteria or their products, pathogen-associated molecular patterns, not only cause intestinal inflammation but also invade the bloodstream through dysbiosis and gut barrier dysfunction, thereby leading to systemic inflammation, namely bacterial translocation. The involvement of bacterial translocation in the carcinogenesis of gastrointestinal cancers and their prognosis is increasingly being recognized. The Toll-like receptor signaling pathways plays an important role in the carcinogenesis of such cancers. In addition, bacterial translocation influences the treatment of cancers such as surgery and chemotherapy. In this review, we outline the concept of bacterial translocation, summarize the current knowledge on the relationship between gut bacteria and gastrointestinal cancer, and provide future perspectives of this field.

Gut Microbiome Signatures Are Predictive of Infectious Risk Following Induction Therapy for Acute Myeloid Leukemia

BACKGROUND

The majority of studies that provide insights into the influence of the microbiome on the health of hematologic malignancy patients have concentrated on the transplant setting. Here, we sought to assess the predictive capacity of the gastrointestinal microbiome and its relationship to infectious outcomes in patients with acute myeloid leukemia (AML).

METHODS

16s rRNA-based analysis was performed on oral swabs and stool samples obtained biweekly from baseline until neutrophil recovery following induction chemotherapy (IC) in 97 AML patients. Microbiome characteristics were correlated with clinical outcomes both during and after IC completion.

RESULTS

At the start of IC, higher stool Shannon diversity (hazard ratio [HR], 0.36; 95% confidence interval [CI], .18-.74) and higher relative abundance of Porphyromonadaceae (HR, 0.36; 95% CI, .18-.73) were associated with increased probability of remaining infection-free during neutropenia. A baseline stool Shannon diversity cutoff of <2 had optimal operating characteristics for predicting infectious complications during neutropenia. Although 56 patients received therapy >72 hours with a carbapenem, none of the patients had an infection with an extended spectrum β-lactamase-producing organism. Patients who received carbapenems for >72 hours had significantly lower α-diversity at neutrophil recovery (P = .001) and were approximately 4 times more likely to have infection in the 90 days following neutrophil recovery (HR, 4.55; 95% CI, 1.73-11.93).

CONCLUSIONS

Our results suggest that gut microbiome evaluation could assist with infectious risk stratification and that improved targeting of antibiotic administration during IC could decrease subsequent infectious complications in AML patients.Baseline microbiome diversity is a strong independent predictor of infection during acute myeloid leukemia induction chemotherapy (IC) among clinical and microbiome covariates. Higher baseline levels of Porphyromonadaceae appear protective against infection, while carbapenem use is associated with consequences to the microbiome and infection susceptibility post-IC.

A multicenter retrospective investigation on the efficacy of perioperative oral management in cancer patients

Patients develop a number of oral complications during cancer treatments. Oral bacteria are associated with the onset of dental focal infections and the progression of oral mucositis. Dental focal infections are frequently associated with the systemic onset of bacteremia, sepsis, and pneumonia. The degeneration of oral function with these complications may become an obstacle to cancer treatments. Although comprehensive oral management, including oral care, the removal of dental focal infections, and improvements in oral function with dentures, is conducted for cancer patients in Japan, few studies have assessed its efficacy.The aim of the present study was to investigate the incidence of dental/oral complications in cancer patients with perioperative oral managements (POMs) based on a large number of case series with a multicenter retrospective analysis.The medical records of cancer patients with POMs were retrospectively reviewed and the incidence of oral complications and efficacy of oral management were investigated.A total of 2744 cancer patients with POMs (1684 males and 1080 females, mean age 65.9 ± 13.0 years) were included and investigated in the present study. Among these patients, 2097 (76.4%) started POM before the initiation of cancer treatments, with 2130 (77.6%) receiving oral care only and 391 (14.2%) being subjected to invasive treatments, such as tooth extraction. The incidence of dental focal infections during the period of cancer treatments was 8.2%. The most frequent infection was acute periodontitis, including alveolar abscesses (112 patients, 4.1%). The incidence of grade 2 and 3 oral mucositis was 2.8%. Prolonged fever was observed in 113 patients (4.1%), with 7 having dental focal infections (6.2%). These incidence rates were lower than those reported previously.Based on analyses of a large number of patients, the present results support the efficacy of oral management in cancer patients. However, further studies are needed to establish adequate oral management guidelines for cancer patients.

The Microbiota in Hematologic Malignancies

OPINION STATEMENT

There are approximately 1.2 million new hematologic malignancy cases resulting in ~ 690,000 deaths each year worldwide, and hematologic malignancies remain the most commonly occurring cancer in children. Even though advances in anticancer treatment regimens in recent decades have considerably improved survival rates, their cytotoxic effects and the resulting long-term complications pose a significant burden on the patients and the health care system. Therefore, non-toxic treatment modalities are needed to decrease side effects. The human body is the host to approximately 40 trillion microbes, known as the human microbiota. The large majority of the microbiota is located in the gastrointestinal tract, and is primarily composed of bacteria. The microbiota plays several important physiological roles, ranging from digestive functions to immunological and neural development. Investigating the microbiota in patients with hematologic malignancies has several important implications. The microbiota affects hematopoiesis, and influences the efficacies of chemotherapy and antimicrobial treatments. Determination of the microbiota composition and diversity could be an important part of risk stratification in the future, and may also take part to personalize antimicrobial treatments. Modulation of the microbiota via probiotics or fecal transplant can potentially be involved in reducing side effects of chemotherapy, and eliminating multiple drug resistant strains in patients with hematologic malignancies.

Lack of Efficacy of the Neutropenic Diet in Decreasing Infections among Cancer Patients: A Systematic Review

The objective of this systematic review is to evaluate the existing evidence supporting the effectiveness of the neutropenic diet in decreasing infection and mortality among cancer patients. We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Scopus for relevant articles published from database inception until March 2019. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed for this review. Individual studies were evaluated using the Oxford Center for Evidence-Based Medicine guidelines. A total of 473 articles were identified and 11 articles were selected after assessing eligibility. Our review showed that the neutropenic diet does not decrease infection rates or mortality among cancer patients. Currently, there is no uniform definition for the neutropenic diet across different institutions. For example, some institutions follow general food safety practices while others avoid foods that increase exposure to microbes and bacteria, and some follow both. Given these differences in practice regarding what constitutes a neutropenic diet, it is advisable that safe food handling and preparation practices recommended by the Food and Drug Administration be uniformly followed for neutropenic patients.

Detection of bacteria in blood circulation in patients receiving cancer chemotherapy

INTRODUCTION

Bacterial translocation, in which intestinal bacteria pass through the intestinal wall, enter the blood circulation, and spread to other sites of the body, is thought to cause bacteremia and sometimes febrile neutropenia (FN) in patients who receive cancer chemotherapy.

MATERIALS AND METHODS

We collected blood samples from 39 patients with various cancers at baseline and after chemotherapy began (during chemotherapy) and explored how frequently bacteria could be detected in the blood using a highly-sensitive, bacterial rRNA-targeted reverse transcription quantitative polymerase chain reaction (PCR) assay.

RESULTS

Bacterial traces, typically Escherichia coli and Enterobacter spp., were detected in 10 patients (25.6%) at baseline and 11 patients (28.2%) during chemotherapy. The bacterial traces were positive either at baseline or during chemotherapy in 3 (60%) of 5 patients who had FN, and 6 (46%) of 13 patients aged 65 years or older.

CONCLUSION

These findings support the notion that bacterial translocation occurs in patients with cancer regardless of whether they receive chemotherapy and can lead to the development of FN and other treatment-related infections.

Urine cultures at the onset of febrile neutropenia rarely impact antibiotic management in asymptomatic adult cancer patients

PURPOSE

There is a paucity of data regarding the utility of routine urine cultures in adults with febrile neutropenia (FN) without urinary symptoms receiving protocolised antibiotics. This is reflected by inconsistent recommendations in international and regional FN guidelines. We addressed this issue by retrospectively reviewing the impact of routine urine cultures on antibiotic management in haematology cancer inpatients at a tertiary hospital.

METHODS

All haematology inpatients over a 5-year period (2011-2015) were retrospectively reviewed for episodes of FN (neutrophil count < 0.5 × 10⁹/L and fever > 37.5 °C). For each episode, demographic data, urinary tract symptoms and signs (absence of which was termed 'asymptomatic'), urinalysis and urine culture results, antibiotic therapy and duration, and patient outcomes were collected. A urine culture was considered positive if > 10⁵ colony forming units (CFU)/L were detected. Empiric antibiotic therapy for FN consisted of intravenous piperacillin/tazobactam in stable patients, with the addition of vancomycin and a single dose of gentamicin if systemically compromised.

RESULTS

Four hundred and thirty-three episodes of FN were identified in 317 patients. Urine cultures were performed in 362 (84%) episodes. Cultures were positive in 9 of 48 (19%) symptomatic episodes versus 8 of 314 (2.5%) asymptomatic episodes (RR = 7.4, p < 0.0001). A change in antibiotic management due a positive urine culture occurred in only 5 episodes (1.4%): 3 of 48 (6.3%) symptomatic and 2 of 314 (0.6%) asymptomatic episodes respectively (RR = 9.8, p = 0.01).

CONCLUSION

Routine urine cultures in FN patients without urinary symptoms who are already receiving protocolised broad spectrum antibiotics rarely impact subsequent antibiotic management.

Role of toll-like receptor 4 (TLR4)-mediated interleukin-6 (IL-6) production in chemotherapy-induced mucositis

Despite significant advances in our ability to treat cancer, cytotoxic chemotherapy continues to be the mainstay treatment for many solid tumours. Chemotherapy is commonly associated with a raft of largely manageable adverse events; however, gastrointestinal (GI) toxicity (also termed mucositis) remains a significant challenge with little in the way of preventative and therapeutic options. The inability to manage GI complications likely reflects our incomplete understanding of its aetiology and the idiosyncrasies of each chemotherapeutic agent. This review highlights aims to provide a narrative for the involvement of Toll-like receptor (TLR4) in the development of chemotherapy-induced GI mucositis, an already emerging theme within this field. Particular focus will be placed upon the signalling interaction between TLR4 and interleukin (IL)-6. This parallels recent preclinical findings showing that TLR4 knockout mice, which are protected from developing severe GI mucositis, completely lack an IL-6 response. As such, we suggest that this signalling pathway presents as a novel mechanism with potential for therapeutic intervention.

Role of Procalcitonin in the Management of Infected Patients in the Intensive Care Unit

The combination of molecular pathogen diagnostics and the biomarker procalcitonin (PCT) are changing the use of antimicrobials in patients admitted to critical care units with severe community-acquired pneumonia, possible septic shock, or other clinical syndromes. An elevated serum PCT level is good supportive evidence of a bacterial pneumonia, whereas a low serum PCT level virtually eliminates an etiologic role for bacteria even if the culture for a potential bacterial pathogen is positive. Serum PCT levels can be increased in any shocklike state; a low PCT level eliminates invasive bacterial infection as an etiology in more than 90% of patients.

Protective Effects of Enteral Nutrition Supplemented with Crassostrea hongkongensis Polysaccharides Against 5-Fluorouracil-Induced Intestinal Mucosal Damage in Rats

Chemotherapeutics, including 5-fluorouracil (5-FU), often damage the intestinal mucosal barrier and cause intestinal mucositis (IM). Supplementation with immunoregulatory polysaccharides from Crassostrea hongkongensis has been shown to positively influence the effectiveness and toxicity of 5-FU. Therefore, we studied the effects of oyster polysaccharides on 5-FU-induced intestinal mucosal damage in rats. The C_30-60% ethanol-precipitated fraction of polysaccharides promoted IEC-6 cell proliferation and exhibited a maximal effect at a 0.0195 mg/mL concentration. Moreover, treatment with C_30-60% polysaccharide-based nutrition formula (OPNF) partially prevented the 5-FU-induced degenerative changes in the histology and ultrastructure of small intestinal mucosa. In addition, the endotoxin level of rats fed with 5-FU and OPNF decreased to the normal control level. Furthermore, the 5-FU-induced increase of proinflammatory cytokine interleukin (IL)-2 and the decrease of anti-inflammatory cytokine IL-10 level in the peripheral blood were significantly attenuated by OPNF administration. In conclusion, Oyster C_30-60% polysaccharides can ameliorate 5-FU-induced IM by partially preventing mucosal damage, reducing inflammation, and promoting immunity.

Impact of the Microbiota on Bacterial Infections during Cancer Treatment

Patients being treated for cancer are at high risk for infectious complications, generally due to colonizing organisms that gain access to sterile sites via disrupted epithelial barriers. There is an emerging understanding that the ability of bacterial pathogens, including multidrug-resistant organisms, to colonize and subsequently infect humans is largely dependent on protective bacterial species present in the microbiome. Thus, herein we review recent studies demonstrating strong correlations between the microbiome of the oncology patient and infections occurring during chemotherapy. An increased knowledge of the interplay between potential pathogens, protective commensals, and the host immune system may facilitate the development of novel biomarkers or therapeutics that could help ameliorate the toll that infections take during the treatment of cancer.

Endotoxemia as a diagnostic tool for patients with suspected bacteremia caused by gram-negative organisms: a meta-analysis of 4 decades of studies

The clinical significance of endotoxin detection in blood has been evaluated for a broad range of patient groups in over 40 studies published over 4 decades. The influences of Gram-negative (GN) bacteremia species type and patient inclusion criteria on endotoxemia detection rates in published studies remain unclear. Studies were identified after a literature search and manual reviews of article bibliographies, together with a direct approach to authors of potentially eligible studies for data clarifications. The concordance between GN bacteremia and endotoxemia expressed as the summary diagnostic odds ratios (DORs) was derived for three GN bacteremia categories across eligible studies by using a hierarchical summary receiver operating characteristic (HSROC) method. Forty-two studies met broad inclusion criteria, with between 2 and 173 GN bacteremias in each study. Among all 42 studies, the DORs (95% confidence interval) were 3.2 (1.7 to 6.0) and 5.8 (2.4 to 13.7) in association with GN bacteremias with Escherichia coli and those with Pseudomonas aeruginosa, respectively. Among 12 studies of patients with sepsis, the proportion of endotoxemia positivity (95% confidence interval) among patients with P. aeruginosa bacteremia (69% [57 to 79%]; P=0.004) or with Proteus bacteremia (76% [51 to 91%]; P=0.04) was significantly higher than that among patients without GN bacteremia (49% [33 to 64%]), but this was not so for patients bacteremic with E. coli (57% [40 to 73%]; P=0.55). Among studies of the sepsis patient group, the concordance of endotoxemia with GN bacteremia was surprisingly weak, especially for E. coli GN bacteremia.