Diagnosis of bloodstream infections in immunocompromised patients by real-time PCR.
OBJECTIVE
The diagnosis of bloodstream infections (BSIs) in immunocompromised patients, such as patients with cancer, is challenging. Although blood culture (BC) is considered the standard diagnostic tool for BSIs, it takes several days to yield results and has low sensitivity in these patients. Here, we tested a novel method for diagnosing BSIs in a large cohort of immunodepressed patients.


METHODS
Real-time PCR (LightCycler SeptiFast Test M(GRADE), Roche Diagnostics) was compared with BC for its ability to detect bacteria and fungi in blood samples from 100 immunocompromised patients (98 with cancer) in whom sepsis was suspected.


RESULTS
In concordant samples (79.2% of total cases), real-time PCR identified the presence or absence of microbes significantly faster than BC (p=3.7x10(-49), t-test). Furthermore, in 6 cases, SeptiFast distinguished contamination of BCs by coagulase-negative staphylococci. SeptiFast, however, failed to detect 5 cases of clinically relevant BSI that tested positive by BC.


CONCLUSIONS
SeptiFast rapidly diagnosed BSIs in our cohort of immunosuppressed patients. The results of this study suggest that SeptiFast can be used in conjunction with, but cannot replace, BC to better identify the etiology of fever in immunocompromised patients.
Unit of Microbiology, Department of Haematology and Oncology L. e A. Seràgnoli, University of Bologna, St. Orsola-Malpighi Hospital, via Massarenti 9, 40138 Bologna, Italy.
Stefania
S
Varani
Marta
M
Stanzani
Michela
M
Paolucci
Fraia
F
Melchionda
Gastone
G
Castellani
Lorenzo
L
Nardi
Maria Paola
MP
Landini
Michele
M
Baccarani
Andrea
A
Pession
Vittorio
V
Sambri
D000328:Adult; D002648:Child; D004269:DNA, Bacterial / Q000302:isolation & purification; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D006801:Humans; D016867:Immunocompromised Host; D009369:Neoplasms / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D018805:Sepsis / Q000175:diagnosis*; D013997:Time Factors
D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer