Empiric antimicrobial therapy of febrile neutropenic patients undergoing haematopoietic stem cell transplantation

Randomized study of cefepime versus ceftazidime plus amikacin in patients with solid tumors treated with high dose chemotherapy (HDC) and peripheral blood stem cell support (PBSCS) with febrile neutropenia

OBJECTIVE

This randomized clinical trial evaluated the efficacy and safety of monotherapy with cefepime for patients with solid tumors treated with high dose chemotherapy (HDC) and peripheral blood stem cell support (PBSCS) with febrile neutropenia.

SUBJECTS

Patients with solid tumors treated with HDC and PBSCS, that developed fever and neutropenia (absolute neutrophil count < 500 cells/microL) were eligible, and randomly assigned to receive ceftazidime plus amikacin or cefepime.

RESULTS

Fifty-one episodes were randomized, and all were evaluable (27 received ceftazidime plus amikacin arm, and 24 cefepime). Major efficacy endpoints did not show significant differences, with success rates of 44.4% and 54.2% (p = 0.481) for the combination arm and the monotherapy arm, respectively. The proportion of patients that became afebrile in the first 24 hours was significantly higher in the cefepime group (41.7% vs 11.1%, respectively; p = 0.012). However, due to its premature closure and small sample size, this study lacks the adequate power to definitely address this question.

CONCLUSIONS

Cefepime monotherapy appeared to have an equivalent efficacy and safety as empiric treatment in febrile neutropenia episodes in a highrisk population compared with ceftazidime and amikacin. Nevertheless, this study is not adequately powered to answer this question. Given the small number of patients randomized and the single-center nature of this study, these results must be cautiously interpreted.

Randomized controlled trial of once- versus thrice-daily tobramycin in febrile neutropenic children undergoing stem cell transplantation

BACKGROUND

The benefits of aminoglycoside antibiotics, such as tobramycin, administered as a once-daily dose to manage febrile neutropenia, have been demonstrated in many patient populations. However, toxicity and safety data are lacking for pediatric stem cell transplant recipients, who are at especially high risk for aminoglycoside-related toxicity and infectious morbidity. In particular, the relative nephrotoxicity and efficacy of tobramycin administered as a single daily dose or as three daily doses among this patient population is not known.

METHODS

We conducted a randomized, double-blind controlled study of tobramycin dosing among children 18 years or younger who had fever and neutropenia while undergoing stem cell transplantation. From October 2000 through November 2002, 60 children were randomly assigned to receive intravenous tobramycin, as either a single daily dose (n = 29) or every 8 hours (n = 31), in combination with either piperacillin or ceftazidime (intravenous). Tobramycin doses were adjusted to achieve pharmacokinetic targets. The primary outcome was nephrotoxicity, as represented by the maximal percent increase in serum creatinine concentration throughout the episode of febrile neutropenia relative to the baseline serum creatinine concentration. Efficacy was a secondary outcome and was defined as survival of the episode without modification of the antibacterial regimen. All statistical tests were two-sided.

RESULTS

In a modified intent-to-treat analysis, the mean maximal percent increase in serum creatinine concentration was 32% (N = 26) in the once daily dose group and 51% (N = 28) in the every 8 hours dose group (difference = 19%, 95% confidence interval [CI] = 0% to 38%; P =.054). Among patients evaluable for efficacy, 12 (46%) of 26 patients in the once daily dose group and five (19%) of 27 patients in the every 8 hours dose group survived the episode of febrile neutropenia without requiring antibacterial treatment modification (difference = 27%, 95% CI = 4% to 52%; P =.03). There was one death in each group.

CONCLUSIONS

In febrile neutropenic children undergoing stem cell transplantation, tobramycin may be less nephrotoxic and more efficacious when administered as a once daily dose than when administered every 8 hours.

Empiric carbapenem monotherapy in pediatric bone marrow transplant recipients

OBJECTIVE

To determine which carbapenem (imipenem/cilastatin or meropenem) was the preferable empiric antibiotic monotherapy in pre-engrafted pediatric bone marrow transplant (BMT) patients in terms of patient tolerance, therapeutic efficacy, and cost.

METHODS

We prospectively analyzed 16 pediatric BMT patients who received meropenem, and retrospectively analyzed 16 matched patients who had received imipenem/cilastatin for BMT procedures during the prior 2-year period. We evaluated the patients for evidence of bacterial infection, necessity for concurrent antibiotics, vomiting episodes, duration of concurrent total parenteral nutrition (TPN), and cost of therapy.

RESULTS

We found no differences in the number of culture proven or clinically suspected breakthrough bacterial infections or the need for concurrent additional antibiotics between the groups. Our analysis found that patients who received meropenem experienced significantly less vomiting than those in the imipenem/cilastatin cohort. Our data showed both direct and indirect cost savings for the meropenem group. The statistical and clinical differences in the number of vomiting episodes between these groups impacted other aspects of patient care, antiemetic use, and TPN duration.

CONCLUSIONS

By switching to meropenem, we reduced the cost of antiemetic therapy per patient treatment course, and also showed a trend toward reduced duration of TPN. We found that meropenem provided both clinical and fiscal advantages over imipenem/cilastatin as empiric antibiotic monotherapy in neutropenic pediatric BMT patients.

Changing pattern of bacterial susceptibility to antibiotics in hematopoietic stem cell transplant recipients

Adequate infection prophylaxis and empirical antibiotic therapy are of critical importance after hematopoietic stem cell transplantation (HSCT). We examined the evolution of bacterial susceptibility to antibiotics in 492 patients (198 allografts and 294 autografts) transplanted between 1982 and 1999 and evaluated whether ciprofloxacin prophylaxis and an empirical antibiotic regimen (glycopeptide + third-generation cephalosporin) were still valid. We collected all susceptibility tests performed during the initial hospitalization on blood cultures as well as routine surveillance cultures and analyzed susceptibility to ciprofloxacin and to major antibiotics used in our unit. Gram-positive cocci rapidly became resistant to ciprofloxacin (susceptibility around 70% in 1990 to less than 20% in 1998) but sensitivity to glycopeptides remained unaltered. There was a rapid decline in the number of patients colonized with Gram-negative bacilli in the early years of ciprofloxacin prophylaxis. However, susceptibility to ciprofloxacin fell sharply from around 90% in 1990 to around 30% in 1999. In parallel, susceptibility to ceftazidime also decreased to less than 80% in recent years. Piperacillin (+/- tazobactam) did not show any variation over time and its efficacy remained too low (about 60%). Imipenem as well as recently introduced cefepim and meropenem showed stable and excellent profiles (>90% susceptibility).

IN CONCLUSION

(1) quinolone prophylaxis has now lost most of its value; (2) the choice of a third-generation cephalosporin for empirical antibiotic therapy may no longer be the best because of the emergence of Gram-negative strains resistant to beta-lactamases, such as Enterobacter sp. More appropriate regimens of empirical antibiotic therapy in HSCT recipients may be based on the use of a carbapenem or fourth-generation cephalosporin.