Administration of antibiotic agents before intraoperative sampling in orthopedic infections alters culture results.
Many physicians and surgeons think that prescribing antibiotics before intraoperative sampling does not alter the microbiological results.


METHODS
Case-control study of adult patients hospitalized with orthopedic infections.


RESULTS
Among 2740 episodes of orthopedic infections, 1167 (43%) had received antibiotic therapy before surgical sampling. Among these, 220 (19%) grew no pathogens while the proportion of culture-negative results in the 2573 who had no preoperative antibiotic therapy was only 6%. By multivariate analyses, pre-operative antibiotic exposure was associated with significantly more culture-negative results (odds ratio 2.8, 95% confidence interval 2.1-3.7), more non-fermenting rods and skin commensals (odds ratio 2.8 and 3.0, respectively). Even a single pre-operative dose of antibiotic was significantly associated with subsequent culture-negative results (19/93 vs. 297/2350; χ²-test, p = 0.01) and skin commensals (17/74 vs. 274/2350; p = 0.01) compared to episodes without preceding prophylaxis.


CONCLUSIONS
Prior antibiotic use, including single-dose prophylactic administrations, is three-fold associated with culture-negative results, non-fermenting rods and resistant skin commensals.
Orthopedic Surgery Service, Geneva University Hospitals & Medical School, University of Geneva, Switzerland.
Mohamed
M
Al-Mayahi
Orthopedic Surgery Service, Geneva University Hospitals & Medical School, University of Geneva, Switzerland.
Anais
A
Cian
Service of Infectious Diseases, Geneva University Hospitals & Medical School, University of Geneva, Switzerland; Department of Infectious Diseases, University of Oxford, United Kingdom.
Benjamin A
BA
Lipsky
Orthopedic Surgery Service, Geneva University Hospitals & Medical School, University of Geneva, Switzerland.
Domizio
D
Suvà
Orthopedic Surgery Service, Geneva University Hospitals & Medical School, University of Geneva, Switzerland.
Camillo
C
Müller
Infection Control Program, Geneva University Hospitals & Medical School, University of Geneva, Switzerland.
Caroline
C
Landelle
Orthopedic Surgery Service, Geneva University Hospitals & Medical School, University of Geneva, Switzerland.
Hermès H
HH
Miozzari
Orthopedic Surgery Service, Geneva University Hospitals & Medical School, University of Geneva, Switzerland; Service of Infectious Diseases, Geneva University Hospitals & Medical School, University of Geneva, Switzerland. Electronic address: ilker.uckay@hcuge.ch.
Ilker
I
Uçkay
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D019072:Antibiotic Prophylaxis; D001419:Bacteria / Q000302:isolation & purification*; D001850:Bone Diseases, Infectious / Q000382:microbiology / Q000601:surgery*; D002062:Bursitis / Q000382:microbiology / Q000601:surgery; D016022:Case-Control Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D007592:Joint Diseases / Q000382:microbiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011300:Preoperative Care; D016459:Prosthesis-Related Infections / Q000382:microbiology / Q000601:surgery*; D012189:Retrospective Studies; D018461:Soft Tissue Infections / Q000382:microbiology / Q000601:surgery*
D000900:Anti-Bacterial Agents
Antibiotic prophylaxis; Antibiotics; Culture results; Microbiological cultures; Osteoarticular infections; Selection; Soft tissue infections