Rapid detection of Pseudomonas aeruginosa from positive blood cultures by quantitative PCR.
BACKGROUND
Pseudomonas aeruginosa is responsible for numerous bloodstream infections associated with severe adverse outcomes in case of inappropriate initial antimicrobial therapy. The present study was aimed to develop a novel quantitative PCR (qPCR) assay, using ecfX as the specific target gene, for the rapid and accurate identification of P. aeruginosa from positive blood cultures (BCs).


METHODS
Over the period August 2008 to June 2009, 100 BC bottles positive for gram-negative bacilli were tested in order to evaluate performances of the qPCR technique with conventional methods as gold standard (i.e. culture and phenotypic identification).


RESULTS
Thirty-three strains of P. aeruginosa, 53 strains of Enterobactericaeae, nine strains of Stenotrophomonas maltophilia and two other gram-negative species were isolated while 3 BCs were polymicrobial including one mixture containing P. aeruginosa. All P. aeruginosa clinical isolates were detected by qPCR except a single strain in mixed culture. Performances of the qPCR technique were: specificity, 100%; positive predictive value, 100%; negative predictive value, 98.5%; and sensitivity, 97%.


CONCLUSIONS
This reliable technique may offer a rapid (<1.5 h) tool that would help clinicians to initiate an appropriate treatment earlier. Further investigations are needed to assess the clinical benefit of this novel strategy as compared to phenotypic methods.
Cattoir
Vincent
V
Laboratoire de Bactériologie-Virologie-Hygiène, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, Créteil, France. cattoir-v@chu-caen.fr
Gilibert
Audrey
A
Le Glaunec
Jeanne-Marie
JM
Launay
Nathalie
N
Bait-Mérabet
Lilia
L
Legrand
Patrick
P
D001431:Bacteriological Techniques / Q000379:methods; D001769:Blood / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis*; D004755:Enterobacteriaceae / Q000302:isolation & purification; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011552:Pseudomonas Infections / Q000175:diagnosis*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D020588:Stenotrophomonas / Q000302:isolation & purification
D004269:DNA, Bacterial