PCR Analysis of Bacteria and Fungi in Early Phase of Hematopoietic Stem Cell Transplantation

Management of febrile neutropenia in patients receiving allogeneic hematopoietic stem cell transplantation (HCT) is crucial for successful treatment, but precise pathogen identification is difficult because the sensitivity of blood culture remains low, making the antimicrobial therapy empiric. This study aimed to detect and identify bacterial and fungal pathogens from peripheral blood samples during early phase of HCT, using highly sensitive PCR method which is able to detect and identify a broad range of bacteria and fungi (J Clin Microbiol. 48(6):2030-6, 2010) and to assess the clinical usefulness of PCR analysis in managing febrile neutropenia after HCT.

Patients and Methods: Ten consecutive patients who underwent HCT in our institute between June 2007 and December 2009 were enrolled. Eight patients received TBI-based conventional and two received reduced-intensity preparative regimens. All patients received antibacterial prophylaxis with fluoroquinolone and antifungal prophylaxis by mold-active azole with temporary use of micafungin. We prospectively performed PCR analysis and blood culture of blood samples at least once a week for the first 30 days of HCT. For species identification, positive PCR products were sequenced.

In a total of 56 analyses, bacteria were detected in 23 cases with PCR but in only one case with blood culture. In the febrile patients, 18 cases out of 37 PCR analyses were positive for bacteria, while, in afebrile cases, 5 cases out of 19 PCR analyses were positive for bacteria. In 17 pathogen identified cases, 14 were gram positive cocci and 3 were gram negative rods. Most of the identified pathogens were oral and intestinal bacteria reflecting grade 3 severe mucositis. Fever was manageable in most cases with empiric use of antibiotics, but several series of antibiotic change was required in 2 cases, in which bacteria susceptible to specific antibiotics such as Stenotrophomonas maltophilia were detected. In several cases suffering from severe diarrhea, pathogen could not be identified because PCR products formed multiple peaks. Fungi were detected in only 4 cases, of which 2 cases were provable Aspergillus infection and another 2 cases possessed no other evidence of fungal infection.

Bacterial pathogens mostly associated with oral and intestinal mucositis were detected with PCR in approximately half cases of febrile neutropenia, but fever was manageable in most cases with empiric antibiotic therapy by experienced physicians. PCR analysis was considered to be useful in febrile neutropenia due to bacteria susceptible to specific antibiotics such as Stenotrophomonas maltophilia. More rapid and simplified approach which targets clinically important pathogens such as Stenotrophomonas maltophilia that requires specific use of antibiotics may be useful and reasonable to provide support for the choice of antibiotics in clinical practice.

No relevant conflicts of interest to declare.