Accuracy and potential usefulness of triplex real-time PCR for improving antibiotic treatment of patients with blood cultures showing clustered gram-positive cocci on direct smears.
Bacterial identification and antibiotic susceptibility testing currently require 48 h when a first blood culture (BC) is positive for clustered gram-positive cocci on direct smear examination (DSE). Meanwhile, antibiotic treatment is often inadequate, reducing the chances of effective treatment or creating unnecessary selective pressure. A new real-time PCR (RT-PCR) technique that differentiates Staphylococcus aureus from coagulase-negative staphylococci (CoNS) and detects methicillin resistance in 90 min in BC bottles could help solve these problems. BC bottles from 410 patients with gram-positive cocci on DSE were processed by current methods, and patients' treatments were prospectively recorded. The RT-PCR assay was performed on aliquots of these BCs, which had been kept frozen. For the 121 patients who had true bacteremia, we established whether the faster availability of RT-PCR results could have led to the initiation of treatments different from those actually given. RT-PCR sensitivity and specificity were 100% for differentiating between S. aureus and CoNS and detecting methicillin resistance with two manufacturers' BC bottles. For 31/86 (36%) of the S. aureus-infected patients and for 8/35 (23%) of the CoNS-infected patients who either had suboptimal or nonoptimal treatment or were untreated 48 h after positivity was detected, the early availability of RT-PCR results could have allowed more effective treatment. Unnecessary glycopeptide treatments could have been avoided for 28 additional patients. The use of RT-PCR would increase treatment effectiveness in patients with staphylococcal bacteremia and reduce the selective pressure created by glycopeptides.
Ruimy
Raymond
R
Hospital Group Bichat-Claude Bernard, Laboratoire de Bactériologie, 46, Rue Henri-Huchard, 75018 Paris, France. raymond.ruimy@bch.ap-hop-paris.fr
Dos-Santos
Marie
M
Raskine
Laurent
L
Bert
Frédéric
F
Masson
René
R
Elbaz
Sandrine
S
Bonnal
Christine
C
Lucet
Jean-Christophe
JC
Lefort
Agnès
A
Fantin
Bruno
B
Wolff
Michel
M
Hornstein
Michele
M
Andremont
Antoine
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D016470:Bacteremia / Q000175:diagnosis* / Q000188:drug therapy* / Q000382:microbiology; D001431:Bacteriological Techniques; D001769:Blood / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D003030:Coagulase / Q000378:metabolism; D003470:Culture Media; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology; D006095:Gram-Positive Cocci / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D013997:Time Factors
D000900:Anti-Bacterial Agents; D003030:Coagulase; D003470:Culture Media; D008712:Methicillin