The need for aminoglycosides in combination with β-lactams for high-risk, febrile neutropaenic patients with leukaemia

Effectiveness of Antibiotic Combination Treatments to Control Heteroresistant Salmonella Typhimurium

This study was designed to assess the interactions between antibiotics in combination treatments of Salmonella enterica serovar Typhimurium in association with the development of antibiotic heteroresistance. Salmonella Typhimurium ATCC 19585 (ST^WT), ciprofloxacin (CIP)-induced S. Typhimurium ATCC 19585 (ST^CIP), and clinically isolated antibiotic-resistant S. Typhimurium CCARM 8009 (ST^CLI) treated with antibiotic alone (cephalothin [CEP], CIP, ceftriaxone [CEF], and tobramycin [TOB]) and combination antibiotics (CEP-CIP and CEF-TOB) were used to compare the antibiotic susceptibility, resistance fitness, and cross-resistance. The susceptibilities of ST^WT, ST^CIP, and ST^CLI to CEP were not significant differences between CEP and CEP-CIP treatments, whereas those of ST^WT, ST^CIP, and ST^CLI to TOB were significant differences between TOB and CEF-TOB treatments. The interactions between CEP and CIP in the combination treatment showed mutually synergistic activities against ST^WT and ST^CLI. For the CEF-TOB combination treatments, TOB helped enhance the antibiotic activity of CEF against ST^WT, showing directional synergistic effect. The CEF-TOB combination treatment increased bactericidal activity against ST^WT, ST^CIP, and ST^CLI without causing injured cells. The combination antibiotic treatments (CEP-CIP and CEF-TOB) increased the fitness cost (relative fitness = 0.7) and decreased the cross-resistance of ST^WT, ST^CIP, and ST^CLI when exposed to different classes of antibiotics. This study provides new insight for designing combination antibiotic regimens that can synergistically enhance the antimicrobial activity against antibiotic-resistant Salmonella and inhibit the emergence of cross-resistance to different classes of antibiotics.

Zingiber officinale: Its antibacterial activity on Pseudomonas aeruginosa and mode of action evaluated by flow cytometry

Biofilm formation, low membrane permeability and efflux activity developed by Pseudomonas aeruginosa, play an important role in the mechanism of infection and antimicrobial resistance. In the present study we evaluate the antibacterial effect of Zingiber officinale against multi-drug resistant strain of P. aeruginosa. The study explores antibacterial efficacy and time-kill study concomitantly the effect of herbal extract on bacterial cell physiology with the use of flow cytometry and inhibition of biofilm formation. Z. officinale was found to inhibit the growth of P. aeruginosa, significantly. A major decline in the Colony Forming Units was observed with 3 log10 at 12 h of treatment. Also it is found to affect the membrane integrity of the pathogen, as 70.06 ± 2.009% cells were found to stain with Propidium iodide. In case of efflux activity 86.9 ± 2.08% cells were found in Ethidium bromide positive region. Biofilm formation inhibition ability was found in the range of 68.13 ± 4.11% to 84.86 ± 2.02%. Z.officinale is effective for killing Multi-Drug Resistant P. aeruginosa clinical isolate by affecting the cellular physiology and inhibiting the biofilm formation.

Antimicrobial treatment of febrile neutropenia: pharmacokinetic-pharmacodynamic considerations

Patients with cancer or hematologic diseases are particularly at risk of infection leading to high morbidity, mortality and costs. Extensive data show that optimization of the administration of antimicrobials according to their pharmacokinetic and pharmacodynamic parameters improves clinical outcome. Evidence is growing that when pharmacokinetic and pharmacodynamic parameters are used to target not only clinical cure but also eradication, the selection resistance is also contained. This is of particular importance in patients with neutropenia in whom increasing rates of drug-resistant Gram-negative bacteria have been reported, particularly Pseudomonas aeruginosa. Based on experimental and clinical studies, pharmacokinetic and pharmacodynamic parameters are discussed in this review for each antibiotic used in febrile neutropenia in order to help physicians improve dosing and optimization of antimicrobial agents.

Aetiology and resistance in bacteraemias among adult and paediatric haematology and cancer patients

OBJECTIVES

A knowledge of current epidemiology and resistance patterns is crucial to the choice of empirical treatment for bacteraemias in haematology and cancer patients.

METHODS

A literature review on bacteraemias in cancer patients considered papers published between January 1st 2005 and July 6th 2011. Additionally, in 2011, a questionnaire on the aetiology and resistance in bacteraemias, and empirical treatment, was sent to participants of the European Conference on Infections in Leukemia (ECIL) meetings; recipients were from 80 haematology centres.

RESULTS

For the literature review, data from 49 manuscripts were analysed. The questionnaire obtained responses from 39 centres in 18 countries. Compared with the published data, the questionnaire reported more recent data, and showed a reduction of the Gram-positive to Gram-negative ratio (55%:45% vs. 60%:40%), increased rates of enterococci (8% vs. 5%) and Enterobacteriaceae (30% vs. 24%), a decreased rate of Pseudomonas aeruginosa (5% vs. 10%), and lower resistance rates for all bacteria. Nevertheless the median rates of ESBL-producers (15-24%), aminoglycoside-resistant Gram-negatives (5-14%) and carbapenem-resistant P. aeruginosa (5-14%) were substantial, and significantly higher in South-East vs. North-West Europe.

CONCLUSIONS

The published epidemiological data on bacteraemias in haematology are scanty and mostly dated. Important differences in aetiology and resistance exist among centres. Updated analyses of the local epidemiology are mandatory to support appropriate empirical therapy.

Guidelines for aminoglycoside use and applicability to geriatric patients

OBJECTIVES

The authors had for objective to evaluate the applicability of AFSSAPS guidelines for aminoglycoside use to geriatric patients.

METHODS

Theoretical doses and dosing regimens allowing reaching target concentrations in this population were calculated by applying a pharmacokinetic model to 30 geriatric patients treated by amikacin.

RESULTS

The dose allowing reaching a maximum concentration of 60 mg/L was 1.217 mg on average. The time required to reach a blood concentration lower than or equal to 2.5mg/L was 62.5±70.4 hours. Forty-six percent of patients had a trough concentration greater than 2.5 mg/L, 48 hours after administration. For these patients, the time between critical minimum inhibitory concentration (MIC) and toxicity threshold concentration was 21.9±14.9 hours.

CONCLUSION

Reaching a target concentration can be problematic in geriatric patients. It is frequently necessary to use dosing intervals greater than 48 hours. The effectiveness and safety of these regimens remain uncertain.

Guideline for the management of fever and neutropenia in children with cancer and/or undergoing hematopoietic stem-cell transplantation

PURPOSE

To develop an evidence-based guideline for the empiric management of pediatric fever and neutropenia (FN).

METHODS

The International Pediatric Fever and Neutropenia Guideline Panel is a multidisciplinary and multinational group composed of experts in pediatric oncology and infectious disease as well as a patient advocate. The Panel was convened for the purpose of creating this guideline. We followed previously validated procedures for creating evidence-based guidelines. Working groups focused on initial presentation, ongoing management, and empiric antifungal therapy. Each working group developed key clinical questions, conducted systematic reviews of the published literature, and compiled evidence summaries. The Grades of Recommendation Assessment, Development, and Evaluation approach was used to generate summaries, and evidence was classified as high, moderate, low, or very low based on methodologic considerations.

RESULTS

Recommendations were made related to initial presentation (risk stratification, initial evaluation, and treatment), ongoing management (modification and cessation of empiric antibiotics), and empiric antifungal treatment (risk stratification, evaluation, and treatment) of pediatric FN. For each recommendation, the strength of the recommendation and level of evidence are presented.

CONCLUSION

This guideline represents an evidence-based approach to FN specific to children with cancer. Although some recommendations are similar to adult-based guidelines, there are key distinctions in multiple areas. Implementation will require adaptation to the local context.

P. aeruginosa bloodstream infections among hematological patients: an old or new question?

Pseudomonas aeruginosa is a well-known cause of severe and potentially life-threatening infections among hematological patients. A prospective epidemiological surveillance program ongoing at our Hematology Unit revealed an increase over time of P. aeruginosa bloodstream infections (BSI). Their impact on outcome and antibiotic susceptibility was analyzed. BSI which consecutively occurred at our institution during a 70-month period were evaluated and correlated with type of pathogen, status of underlying disease, neutropenia, previous antibiotic therapy, resistance to antibiotics, and outcome. During the observation period, 441 BSI were recorded. Frequency of Gram-negative BSI was higher than that of other pathogens (57.3%). Overall, 66 P. aeruginosa BSI were recorded; 22 out of 66 were multiresistant (MR P. aeruginosa). Thirty-day mortality for all BSI was 11.3%; it was 27.3% for P. aeruginosa BSI and 36.4% for MR P. aeruginosa. At multivariate analysis, only active hematological disease and P. aeruginosa BSI were associated to an increased risk of death. For MR P. aeruginosa, BSI mortality was 83.3% vs. 18.8% when empiric therapy included or not an antibiotic with in vitro activity against P. aeruginosa (p=0.011). Together with active disease, the emergence of P. aeruginosa BSI, particularly if multiresistant, was responsible for an increased risk of death among hematological patients at our institution. In this scenario, reconsidering the type of combination antibiotic therapy to be used as empiric treatment of neutropenic fever was worthwhile.

Therapeutic drug monitoring of aminoglycosides in acute myeloid leukaemia patients

International guidelines limit the use of aminoglycosides in febrile neutropenia to severe situations. We retrospectively reviewed the use of aminoglycosides in adult acute myeloid leukaemia patients admitted in 2009. Our guidelines include precise indications (severe sepsis, shock, drug resistance), dosing regimens (once-daily 20 mg/kg/day amikacin, 5 mg/kg/day gentamicin), durations of treatment, drug monitoring timing, and target C(max) concentrations (40 mg/l amikacin, 20 mg/l gentamicin). Thirty-one patients received 46 aminoglycoside courses: 31 amikacin and 15 gentamicin. The mean prescribed dosage was 19 ± 2.8 mg/kg/day for amikacin and 4.7 ± 0.9 mg/kg/day for gentamicin. The mean duration of use was 2.9 days for both drugs. The mean C(max) for amikacin was 47 ± 13 mg/l and for gentamicin was 13.6 ± 7.5 mg/l. In compliant regimens, all amikacin patients and a third of gentamicin patients had adequate C(max). Among 23 isolated pathogens, 65.5% were susceptible to both drugs and 11.5% to amikacin only. This vindicates the 20 mg/kg/day amikacin dosage and suggests a need to increase the gentamicin dosage.

Evidence-based guidelines for empirical therapy of neutropenic fever in Korea

Neutrophils play an important role in immunological function. Neutropenic patients are vulnerable to infection, and except fever is present, inflammatory reactions are scarce in many cases. Additionally, because infections can worsen rapidly, early evaluation and treatments are especially important in febrile neutropenic patients. In cases in which febrile neutropenia is anticipated due to anticancer chemotherapy, antibiotic prophylaxis can be used, based on the risk of infection. Antifungal prophylaxis may also be considered if long-term neutropenia or mucosal damage is expected. When fever is observed in patients suspected to have neutropenia, an adequate physical examination and blood and sputum cultures should be performed. Initial antibiotics should be chosen by considering the risk of complications following the infection; if the risk is low, oral antibiotics can be used. For initial intravenous antibiotics, monotherapy with a broad-spectrum antibiotic or combination therapy with two antibiotics is recommended. At 3-5 days after beginning the initial antibiotic therapy, the condition of the patient is assessed again to determine whether the fever has subsided or symptoms have worsened. If the patient's condition has improved, intravenous antibiotics can be replaced with oral antibiotics; if the condition has deteriorated, a change of antibiotics or addition of antifungal agents should be considered. If the causative microorganism is identified, initial antimicrobial or antifungal agents should be changed accordingly. When the cause is not detected, the initial agents should continue to be used until the neutrophil count recovers.