Infectious complications in the cancer patient

Pediatric Febrile Neutropenia: Change in Etiology of Bacteremia, Empiric Choice of Therapy and Clinical Outcomes

BACKGROUND

The optimal choice of initial antibiotic therapy for patients with high-risk febrile neutropenia (FN) in children is unclear and varies by the institution on the basis of local antibiograms and epidemiology of specific pathogens. The authors evaluated the appropriateness of antibiotics for the empiric treatment of FN in pediatric patients with cancer in our institution on the basis of changes in the epidemiology of organisms isolated from blood cultures (BCx).

METHODS

The authors conducted a retrospective medical record review of pediatric patients who received any oncology care (including patients with cancer and patients who had stem cell transplant) at University of Chicago Medicine Comer Children's Hospitals (March 2009 to December 2016) with a diagnosis of FN who had at least 1 BCx obtained. They reviewed pathogens isolated from BCx and determined whether they were pathogens or contaminants using the Infectious Diseases Society of America (IDSA) guidelines and the team's decision to treat. They investigated the microbiologic spectrum and susceptibility patterns of pathogens causing bacteremia in pediatric FN and whether the empiric therapy chosen may have affected clinical outcomes.

RESULTS

A total of 667 FN episodes were identified in 268 patients. BCx were negative in 497 (74.5%) and were determined to be contaminants in 27 (4%). In 143 episodes (21.5%), the BCx were positive for a pathogenic species. Polymicrobial bacteremia was identified in 25 episodes; a total of 176 pathogens were isolated. The majority of pathogens (95/176, 54%) were Gram-positive (GP), whereas 64 of 162 (36%) were Gram-negative (GN), 5 were fungal, and 4 were mycobacterial. The most common GP pathogens were viridans group streptococci (VGS) (n=34, 19.3%), coagulase-negative staphylococci (n=25, 14%), and methicillin-susceptible Staphylococcus aureus (n=12, 6.8%). Of aerobic GN bacilli, 15 (8.5%) were AmpC producers and 3 (1.7%) carried extended-spectrum beta-lactamases. There was no increase in the prevalence of multidrug-resistant GN isolates during the study period. Patients with VGS and multidrug-resistant GN bacteremia were more likely to be admitted to the pediatric intensive care unit [odds ratio (OR), 3.24; P=0.017; and OR, 2.8; P=0.07, respectively]. There were trends toward a higher prevalence of GP pathogens causing bacteremia and the emergence of VGS with decreased penicillin sensitivity. The prevalence of bacteremia with VGS was higher in acute myelogenous leukemia and neuroblastoma (OR, 2.3; P<0.01) than in patients with other solid tumors.

CONCLUSIONS

Empiric antibiotic treatment should be tailored to patients' risk for VGS and multidrug-resistant organisms. Individual hospitals should monitor the pathogens causing FN among patients with cancer to guide choice of empiric therapy.

Antifungal efficacy of amphotericin B encapsulated fibrin microsphere for treating Cryptococcus neoformans infection in Swiss albino mice

A natural and biocompatible fibrin microsphere is one of the most promising dual delivery vehicle as compared to other traditionally designed delivery modalities. It represents sustained delivery of encapsulated drug and is easily biodegradable in the blood circulation. In the present study, we evaluated the systemic augmentation of the antifungal activity of amphotericin B loaded in fibrin microsphere (AMB-fibrin microsphere) against cryptococcosis in Swiss albino mice. Mice infected with Cryptococcus neoformans were treated with 0.5mg/kg AMB-fibrin microsphere that was given alternately for 7 days. The antifungal potential of AMB-fibrin microsphere was assessed on the basis of reduction of cfu count in the systemic circulation and various vital organs of infected mice. The formulation was found to be highly effective in reducing intracellular pathogen from the experimental animals where fibrin microsphere significantly controlled the release of amphotericin B for longer time duration. The AMB-fibrin microsphere chemotherapy was significantly more effective than free amphotericin B in reducing the fungal burden and showed better survival efficacy (p<0.05). The current study demonstrating the use of novel amphotericin B loaded fibrin microsphere not only imparts protection to the encapsulated amphotericin B but also offers an effective strategy to decrease the drug associated toxicities.

Beaded plasma clot: a potent sustained-release, drug-delivery system

Aim: The aim of the study was to prepare a drug-entrapped, beaded form of blood plasma for possible sustained drug delivery. Method: Blood plasma mixed with various drugs was enriched with CaCl2 and transferred in the form of small droplets on to a glass slide covered with parafilm. Clot formation was induced by incubation at 37°C. Results: Plasma-bead entrapped tetracycline, amphotericin B and daunorubicin were released gradually in vitro. Crosslinking of the beads with glutaraldehyde decreased the release rate of drugs remarkably. The plasma bead-entrapped cefotaxime administered subcutaneously in mice was released in a slow and sustained fashion and remained in circulation for a longer duration than the antibiotic administered in the free form. Conclusion: The plasma beads have potential for the sustained delivery of drugs in vivo, since their preparation does not require additional thrombin or other proteins and can be readily accomplished by using autologous plasma, thereby minimizing the risk of immunological complications.

Arabinogalactan protein from Arachis hypogaea: Role as carrier in drug-formulations

Arabinogalactan protein (AGP) a highly water-soluble glyco-conjugate from groundnut (Arachis hypogaea L.) seedling was isolated and purified by precipitation with beta-glucosyl Yariv reagent. Quantification of AGP was done by gel diffusion assay. Purified AGP was conjugated to amphotericin-B (AmB) by Schiff base reaction at pH 11.0, with aim to prepare a water-injectable lesser toxic AGP-AmB conjugate without affecting AmB antifungal potential. The AGP-AmB conjugate antifungal activity was assayed by serial broth dilution and disc method against several Candida albicans clinical isolates. Both AmB and AGP-AmB showed similar MICs and MFCs activities, indicating that AGP do not reduced the antifungal activity of AmB. However, the in vitro and in vivo toxicity assays revealed that AGP-AmB conjugate was lesser toxic than AmB, as high MTD (45 mg/kg body weight) was observed. It is suggested that AGP could be a potent carrier in AmB formulation, which may result in effective treatment of fungal infections.

Changes in the etiology of bacteremia in febrile neutropenic patients and the susceptibilities of the currently isolated pathogens

The etiology of bacteremia in febrile neutropenic patients in the past few decades has shifted from gram-negative to gram-positive organisms. Potential reasons include the use of indwelling catheters, local environmental conditions, and the administration of specific antibiotic agents, especially as prophylaxis. Other factors may emerge from new studies, such as the categorization of febrile neutropenic patients into groups at low risk and at high risk of developing serious complications, continuing changes in resistance in the community, the use of antibiotic-coated catheters, and future changes in cytotoxic chemotherapy or antineoplastic therapy. In addition, there has been a drift in susceptibility patterns, with resistance issues seen in the general population of hospitalized patients now emerging in febrile neutropenic patients, as well as some issues specific to these patients. These changes affect empirical therapy as it was practiced a decade ago. Among the most commonly used agents, cefepime and carbapenems continue to show the highest rates of in vitro susceptibility, providing coverage against most gram-positive and gram-negative organisms and reducing the need for glycopeptides. Older agents continue to show degradation of their effectiveness. Among Pseudomonas aeruginosa strains, susceptibility to all agents continues to decline.

Acute phlegmonous jejunitis and viridans streptococcal peritonitis associated with bronchial carcinoma

A 61-y-old man developed acute non-specific phlegmonous jejunitis associated with relatively mild diffuse peritonitis. Bacteriological cultures of the abundant peritoneal fluid resulted in only growth of viridans streptococci (Streptococcus mitis and S. salivarius). Antibiotic treatment had a favourable effect, but a hitherto unknown bronchial cancer led to his death 5 months later. It is assumed that this peculiar case was the result of the immunosuppressive effect related to the malignant neoplasm (opportunistic infection).

A novel injectable water-soluble amphotericin B-arabinogalactan conjugate

New, stable, highly water-soluble, nontoxic polysaccharide conjugates of amphotericin B (AmB) are described. AmB was conjugated by a Schiff-base reaction with oxidized arabinogalactan (AG). AG is a highly branched natural polysaccharide with unusual water solubility (70% in water). A high yield of active AmB was obtained with the conjugates which were similarly highly water soluble and which could be appropriately formulated for injection. They showed comparable MICs for Candida albicans and Cryptococcus neoformans (MICs, 0.1 to 0.2 microg/ml). The reduced AmB conjugate, which was synthesized at pH 11 for 48 h at 37 degrees C, was nonhemolytic and was much safer than conventional micellar AmB-deoxycholate. It was the least toxic AmB-AG conjugate among those tested with mice (maximal tolerated dose, 50 mg/kg of body weight), and histopathology indicated no damage to the liver or kidneys. This conjugate, similarly to the liposomal formulation (AmBisome), was more effective than AmB-deoxycholate in prolonging survival. It was more effective than both the liposomal and the deoxycholate formulations in eradicating yeast cells from target organs. The overall results suggest that after further development of the AmB-AG conjugate, it may be a potent agent in the treatment of fungal infections.

Efficacy evaluation of a novel submicron miconazole emulsion in a murine cryptococcosis model

Submicron emulsions of miconazole were stabilized by using a combination of three emulsifiers comprising phospholipids, poloxamer, and deoxycholic acid (DCA). The presence of DCA was vital for prolonged emulsion stability owing to its contribution to the elevated zeta potential of the emulsion. Further, the results by the phospholipid surface labelling colorimetric technique clearly suggested that poloxamer molecules interacted with phospholipid polar-head groups of the mixed DCA-phospholipid interfacial film, resulting in the stabilization of the emulsion by a steric enthalpic entropic mechanism. The plain emulsion vehicle was well tolerated up to a dose of 0.6 ml injected i.v. to BALB/c mice. The maximum tolerated dose of miconazole was 80 and 250 mg/kg in Daktarin i.v. (a marketed product) and emulsion, respectively, showing an improved safety ratio of 1 to 3 in favor of the emulsion. These results tended to confirm that the adverse effects associated with Daktarin i.v. injection should be associated with the vehicle rather than with the miconazole itself. In a murine cryptococcosis model, only one mouse out of ten remained alive by day 15 in the infected group treated with Daktarin i.v., while in the miconazole emulsion treated group, mice began to die from day 16 up to day 25 post inoculation. Thus, the multiple-dose treatment with the miconazole emulsions improved the protection offered to the infected mice. However, the therapeutic levels of miconazole that were reached in the target organ (brain) were lower than those required for complete eradication of Cryptococcus neoformans, which is known to multiply preferentially in the brain.

Local radiation and systemic chemotherapy: preventing and managing the oral complications

About 50 percent of cancer patients develop acute or chronic oral side effects from their treatments. Pretreatment strategies, oral care during treatment and close follow-ups can control these complications.

Efficacy evaluation of a novel submicron amphotericin B emulsion in murine candidiasis

A submicron amphotericin B (AmB) sterile emulsion with a mean droplet size of approximately 100 nm was prepared. The emulsion was stable at 4 degrees C over a period of 4 months. The acute toxicity results showed that the maximum tolerated dose of the AmB emulsion was 2.0 mg kg-1 as compared to 0.5 mg kg-1 for a commercial deoxycholate suspension, Fungizone. Efficacy evaluations of submicron AmB emulsion compared to Fungizone were performed in a murine candidiasis model using either a single or a multiple daily dose administration of 0.4 mg kg-1. Survival (100%) was observed up to 15-18 days post-infection in mice treated with AmB emulsion or Fungizone, while all control non-treated animals had died after 9 days in both single and multi-treatment experiments. Survival (50%) was obtained after 35 days in the single treatment, and 40 days in the multi-treatment, experiment with AmB emulsion, while treatment with Fungizone gave 50% survival after 15 and 20 days, respectively. The overall results indicate that in murine candidiasis, treatment with AmB submicron emulsion was more effective than Fungizone, suggesting a potential therapeutic application.

Antifungal treatment strategy in leukemia patients

Among the opportunistic infections in patients with leukemias systemic fungal infections contribute a major part if not the majority. This results from autopsy data and is supported clinically when using new criteria by imaging techniques, while microbiological documentation shows a low sensitivity in this situation. Those lessons require a change in strategy toward an earlier and empiric use of systemic antifungal drugs in the frequent infections appearing as fever of unknown origin. By its high systemic activity and low toxicity Fluconazole facilitates this approach. Amphotericin B with 5-Flucytosine remain as the most established standard. Liposomal Amphotericin B allowing higher dosage by lower toxicity appears effective as salvage treatment especially in aspergillosis which also responds to Itraconazole available as oral formulation so far.

Oral complications associated with cancer therapy. An M. D. Anderson Cancer Center experience

Oral complications associated with cancer therapy may not be inevitable. The intensity and duration can be prevented or alleviated by correcting existing oral-dental pathology and maintaining meticulous oral care. Microbial (bacterial, fungal and viral) assessment not only allows appropriate documentation of mucositis versus mucosal infection but directs therapeutic treatment.

Enzyme immunoconjugates utilizing glucose oxidase and myeloperoxidase are cytotoxic to Candida tropicalis

A dual-enzyme immunoconjugate system was evaluated for its cytotoxic effect on Candida tropicalis. Glucose oxidase, which generates hydrogen peroxide in the presence of glucose and oxygen and myeloperoxidase, which catalyzes the oxidation of halides in the presence of hydrogen peroxide, were each conjugated to a C. tropicalis-specific monoclonal antibody. Neither the glucose oxidase nor the myeloperoxidase conjugates exhibited any significant cytotoxic effect by themselves. A combination of glucose oxidase conjugate (3.2 ng/ml) and myeloperoxidase conjugate (12.8 ng/ml) in the presence of 5 mg of glucose per ml, 150 mM chloride, and 50 microM iodide was cytotoxic to C. tropicalis, killing 99.9% of the treated sample. Flow cytometry was used to characterize the binding of the conjugates to yeast cells and demonstrated that the binding of both conjugates to the yeast cell surface is required for cytotoxicity. In addition, the concentrations of conjugates required for a cytotoxic effect were below the concentrations required to saturate all of the yeast cell surface antibody-binding sites.

Oral infections and fever in immunocompromised patients with haematologic malignancies

The purpose of the study was to determine the prevalence of acute oral infections and to estimate their role as a possible cause of fever in immunocompromised patients with haematologic malignancies. Seventy-eight febrile episodes in 46 patients were analyzed prospectively and consecutively. An association between a rise in the leukocyte and platelet counts and normalization of the temperature was found. Acute infections were present in 92% of the febrile episodes no infectious cause could be demonstrated in the remaining 8%. Acute oral infections were present during 78% and acute extraoral infections during 73% of the febrile episodes. Acute candidiasis and infected mucosal ulcers were the most prevalent oral infections, occurring in about one-half and one-third of the episodes, respectively. Septicaemia and pneumonia were the most prevalent extraoral infections, each present in about one-fourth of the febrile episodes. Acute oral infections were a probable cause of fever in 14% of the febrile episodes and a possible or a contributing cause of fever in a further 26%. The results suggest that effective treatment or prevention of acute oral infections may reduce the morbidity and perhaps even the mortality in immunocompromised patients.

Oral complications of cancer chemotherapy: prevention and management

Cancer chemotherapy is used to destroy rapidly proliferating cells. However, normal cells with high mitotic indexes are also affected by chemotherapy, particularly those in the oral and gastrointestinal mucosa and the hemopoietic system. Ultimately, this may lead to certain oral complications of cancer chemotherapy such as mucositis, infection, hemorrhage, xerostomia, and neurologic and nutritional disorders. The prevention and management of these oral complications that may result from the chemotherapeutic management of cancer are discussed here.

Oral manifestations of systemic chemotherapy and their management

Many antineoplastic drugs in use now have cytotoxic side effects that also manifest in the oral cavity or influence dental management. Chemotherapeutic agents that have a high potential for precipitating oral mucosal damage and bone marrow depression are methotrexate, cyclophosphamide, daunorubicin, doxorubicin hydrochloride, 5-fluorouracil, bleomycin, nitrogen mustard, cytosine-arabinoside, 6-mercaptopurine, busulfan, and L-phenylalanine mustard. Mucositis may lead to neglected oral hygiene, which in turn may cause a chain reaction of local infections, bleeding, and septicemia in myelosuppressed patients. Preventive oral care before chemotherapy and active oral care during therapy are necessary for compromised patients. A protocol for oral care is described.

Selective toxicity and enhanced therapeutic index of liposomal polyene antibiotics in systemic fungal infections

Incorporation of the polyene antibiotic amphotericin B (AMB) in liposomes results in a marked reduction in drug toxicity with no loss of antifungal potency. Nephrotoxicity, the dose-limiting side effect of AMB, is almost abolished when the drug is utilized in a liposomal carrier. Because of reduced toxicity, high doses of liposomal AMB can be used, resulting in superior therapy of systemic fungal infections in mice. The improved therapeutic index of liposomal AMB versus free AMB is also manifest in infected neutropenic animals. The reduced toxicity of liposomal AMB is due to a fundamental alteration in the interaction of the drug with mammalian cell membranes. AMB transfers effectively from donor liposomes to fungal cell walls and membranes and is thus toxic to fungi. By contrast, AMB does not transfer from liposomes to mammalian cells and thus is not toxic to these cells. Thus, the use of liposomal AMB may offer a marked improvement in the therapy of systemic fungal infection in cancer patients and other immunodebilitated individuals.

Infection in the patient receiving chemotherapy for cancer: oral considerations

Because of the various factors associated with the disease process and its treatment, the patient receiving chemotherapy for cancer is highly susceptible to infection, and infection accounts for approximately 70% of patient fatalities. When potential sources of infection are considered in the patient receiving chemotherapy for cancer, the mouth provides ideal conditions for microbial growth, particularly in the debilitated patient, and is a portal of entry for contamination of the lungs, the digestive tract, and the circulatory system. These patients are more susceptible to oral infection because of alteration of oral flora toward greater pathogenicity and impairment of host-defense mechanisms. Oral/dental management of the patient receiving chemotherapy for cancer will enhance the general health and comfort of the patient and will prevent or reduce oral complications including mucositis and local and systemic infection.

Prophylaxis of Candida albicans infection in neutropenic mice with liposome-encapsulated amphotericin B

The efficacy of liposome-encapsulated amphotericin B in the prophylaxis of disseminated Candida albicans infections in neutropenic mice was studied. The administration of liposome-encapsulated amphotericin B was associated with protection against infection with C. albicans when used at doses of greater than or equal to 2 mg of amphotericin B per kg of body weight. Neither empty liposomes nor free amphotericin B showed prophylactic efficacy.

Altered tissue distribution of amphotericin B by liposomal encapsulation: comparison of normal mice to mice infected with Candida albicans

Recently, it has been observed that encapsulation of Amphotericin B (Amp-B) into multilamellar vesicles (liposomes) decreases the toxicity associated with the administration of Amp-B, while maintaining its antifungal efficacy. In this study, the tissue concentrations of Amp-B in normal mice and in mice infected with Candida albicans were examined. Amp-B concentrations in various tissues were quantitated by high-performance liquid chromatography. Liposomal encapsulation improved the delivery of Amp-B to the liver, spleen, lung, and kidney in both normal and infected mice. Furthermore, after injection of the encapsulated drug, Amp-B was demonstrable in brain tissue of infected animals at potentially therapeutic concentrations. None was demonstrable in the brains of normal animals or animals injected with free Amp-B. The results suggest that capillary endothelial damage and phagocytic cell uptake may contribute to an enhanced liposome delivery of Amp-B to those organs most frequently infected with fungi.