Routine surveillance for bloodstream infections in a pediatric hematopoietic stem cell transplant cohort: Do patients benefit?

Limited Utility of Outpatient Surveillance Blood Cultures in Hematopoietic Cell Transplant Recipients on High-Dose Steroids for Treatment of Acute Graft-versus-Host-Disease

Steroids used to treat acute graft-versus-host-disease (GVHD) are believed to blunt clinical symptoms of infection. We aimed to assess the value of weekly surveillance blood cultures (SBCs) drawn in an outpatient setting from hematopoietic cell transplant (HCT) patients receiving high-dose steroids. We hypothesized that most positive outpatient surveillance cultures would be low-pathogenicity, gram-positive organisms and would lead to excess vancomycin therapy. We conducted a retrospective review of blood cultures collected from a cohort of adult HCT patients enrolled in a clinical trial of acute GVHD therapy with high-dose steroids (prednisone-equivalent doses ≥ .5 mg/kg/day) between April 2009 and May 2013. SBCs were defined as those collected weekly from central venous catheters in the outpatient setting while patients were receiving high-dose steroids. Cultures obtained as part of a symptom workup or as follow-up for documented bacteremia were excluded. Clinical data were collected using center databases supplemented by medical record review. One hundred twenty-seven HCT recipients were eligible for inclusion in the study. A total of 1015 SBCs were obtained, with a median of 8 cultures (interquartile range, 5 to 10) per patient. Forty-two organisms were isolated from 36 of 1015 cultures (3.5%) in 30 unique patients, or 1 positive culture per 28 blood cultures drawn. The most frequently detected organisms were coagulase-negative Staphylococci (25/1015 [2.5%]). Gram-negative organisms were rare (4/1015 [.4%]. Antibiotics were administered to most patients with positive surveillance cultures (33/36 [92%]). Six were admitted to the hospital for treatment; none needed intensive care or died from their bacteremia. Vancomycin was the most frequently administered antibiotic, comprising 256 of 376 total days (68%) of antibiotic received by the cohort with a median duration of 10 days ((interquartile range, 7 to 14). Weekly outpatient SBCs obtained from asymptomatic patients on high-dose glucocorticoids for treatment of acute GVHD after allogeneic HCT were infrequently positive, and most organisms were low-pathogenicity organisms. SBCs also led to excess antibiotic exposure and costs, suggesting benefits of such ambulatory screening may be of limited value in this setting.

Febrile Neutropenia in Transplant Recipients

Febrile neutropenic patients are at increased risk of developing infections. During the initial stages of neutropenia, most of these infections are bacterial. The spectrum of bacterial infections depends to some extent on whether or not patients receive antimicrobial prophylaxis when neutropenic. Since most transplant recipients do, Gram-positive organisms predominate, due to the fact prophylaxis is directed primarily against Gram-negative organisms. Staphylococcus species (often methicillin-resistant), Streptococcus species (viridans group streptococci, beta-hemolytic streptococci), and Enterococcus species (including vancomycin-resistant strains) are isolated most often. Therefore, potent empiric Gram-positive coverage is recommended by many in this setting. Escherichia coli, Pseudomonas aeruginosa, and Klebsiella species are the most common Gram-negative pathogens isolated. Non-fermentative Gram-negative bacilli (Stenotrophomonas maltophilia, Acinetobacter species) are emerging as important pathogens. Many of these organisms acquire multiple mechanisms of resistance that render them multidrug resistant. The administration of prompt, broad-spectrum, empiric, antimicrobial therapy is essential and is generally based on local epidemiology and susceptibility/resistance patterns. Response rate to the initial regimen is generally in the range of 75–85%. Fungal infections develop in patients with prolonged neutropenia (greater than 7–10 days). Candida species and Aspergillus species are the predominant fungal pathogens, although many other fungi are opportunistic pathogens in this setting. Fungal infections are seldom documented microbiologically or on histopathology, and the administration of empiric antifungal therapy, when such infections are suspected, is the norm. Therapy is often prolonged, and outcomes are still suboptimal. The importance of infection control and antimicrobial stewardship cannot be overemphasized.

Bacterial bloodstream infections in the allogeneic hematopoietic cell transplant patient: new considerations for a persistent nemesis

Bacterial bloodstream infections (BSI) cause significant transplant-related morbidity and mortality following allogeneic hematopoietic cell transplantation (allo-HCT). This manuscript reviews the risk factors for and the bacterial pathogens causing BSIs in allo-HCT recipients in the contemporary transplant period. In addition, it offers insight into emerging resistant pathogens and reviews clinical management considerations to treat and strategies to prevent BSIs in allo-HCT patients.

Usefulness of daily surveillance blood cultures in allogeneic hematopoietic stem cell transplant recipients on steroids: a 1-year prospective study

BACKGROUND

Bloodstream infections (BSI) are frequent and potentially severe complications in allogeneic hematopoietic stem cell transplant (AHSCT) recipients. In patients on steroids, surveillance blood cultures (SBCs) are routinely performed to detect asymptomatic BSI but their usefulness remains controversial.

METHODS

We performed a 1-year, observational, prospective, single-center study to assess the utility of daily SBCs in AHSCT recipients on steroids and a case-control study to identify risk factors associated with positive SBCs. All blood cultures (BCs) obtained from adults hospitalized in the HSCT unit were prospectively studied throughout 1 year. Characteristics, treatments, and outcome of patients were retrieved from medical charts.

RESULTS

A total of 3594 BCs were obtained in 177 patients, including 1450 SBCs in 82 AHSCT recipients on steroids. In 33 patients, 103 SBCs (7%) were positive. Low-virulence bacteria were identified in 74% of episodes. When analyzing first episode of positive SBCs (28 patients), 6 (21%) true BSI were identified.

CONCLUSIONS

Patients with positive SBCs were receiving antibiotic treatment less frequently at the time of SBCs (P < 0.001) and had more frequently BCs obtained through central venous access (P < 0.04) when compared to patients with negative SBCs. Daily SBCs in AHSCT recipients on steroids only rarely identify BSI and clear benefit for patients could not be demonstrated.

Utility of routine surveillance blood cultures in asymptomatic allogeneic hematopoietic stem cell transplant recipients with indwelling central venous catheters at a comprehensive cancer center

BACKGROUND

Many transplant centers obtain surveillance blood cultures (SBCs) from asymptomatic allogeneic hematopoietic stem cell transplant (allo-HCT) recipients with central venous catheters for early detection of potential blood stream infections. The aim of this study was to determine the utility of this practice.

METHODS

We conducted a retrospective study of all patients who underwent allo-HCT to determine the frequency, clinical significance, and costs associated with SBCs.

RESULTS

From 776 patients, 6,801 SBCs were obtained (median, 9 per patient). Most (96.89%) were negative. Of the 211 positive SBCs, 171 (81%) had minimal clinical significance. The remaining 40 positive cultures (19%) were considered potentially significant. The frequency of potentially significant SBCs was 5.1% for the entire cohort and 0.59% of all SBCs drawn.

CONCLUSION

All potentially significant cultures and some that were deemed to have minimal significance led to medical intervention, some of which were probably unnecessary. No adverse outcomes occurred in patients with positive SBCs for the first 30 days following the positive result, regardless of the pathogen isolated or the quantitative colony count. The frequency of clinically significant positive SBCs in asymptomatic adult allo-HCT recipients is very low. Routine use of this practice leads to some unnecessary medical interventions and added costs.

Utility of surveillance blood cultures in patients undergoing hematopoietic stem cell transplantation

Background

Surveillance blood cultures are often obtained in hematopoietic stem cell transplant (HSCT) patients for detection of bloodstream infection. The major aims of this retrospective cohort study were to determine the utility of the practice of obtaining surveillance blood cultures from asymptomatic patients during the first 100 post-transplant days and to determine if obtaining more than one positive blood culture helps in the diagnosis of bloodstream infection.

Methods

We conducted a 17-month retrospective analysis of all blood cultures obtained for patients admitted to the hospital for HSCT from January 2010 to June 2011. Each patient’s clinical course, vital signs, diagnostic testing, treatment, and response to treatment were reviewed. The association between number of positive blood cultures and the final diagnosis was analyzed.

Results

Blood culture results for 205 patients were reviewed. Cultures obtained when symptoms of infection were present (clinical cultures) accounted for 1,033 culture sets, whereas 2,474 culture sets were classified as surveillance cultures (no symptoms of infection were present). The total number of positive blood cultures was 185 sets (5.3% of cultures obtained) and accounted for 84 positive culture episodes. Incidence of infection in autologous, related allogeneic and unrelated allogeneic transplants was 8.3%, 20.0%, and 28.6% respectively. Coagulase-negative staphylococci were the most common organisms isolated. Based on our application of predefined criteria there were 29 infections and 55 episodes of positive blood cultures that were not infections. None of the patients who developed infection were diagnosed by surveillance blood cultures. None of the uninfected patients with positive blood cultures showed any clinical changes after receiving antibiotics. There was a significant difference between the incidence of BSI in the first and second 50-day periods post-HSCT. There was no association between the number of positive blood cultures and the final diagnosis.

Conclusion

Surveillance blood cultures in patients who have undergone HSCT do not identify bloodstream infections. The number of positive blood cultures was not helpful in determining which patients had infection. Patients are at higher risk of infection in the first 50 days post-transplant period.