Guiding empirical antibiotic therapy in orthopaedics: The microbiology of prosthetic joint infection managed by debridement, irrigation and prosthesis retention.
OBJECTIVE
This study describes the microbiological spectrum of prosthetic joint infection (PJI) managed by debridement, washout and retention and so guides the choice of empirical antibiotics within this patient group.


METHODS
We performed a retrospective review of all patients admitted to our specialist tertiary unit for PJI who were managed with debridement and irrigation or arthroscopic washout of infected prosthetic joints between 1st January 1998 and 30th April 2003. Clinical and microbiological data sets were analysed using the Access database.


RESULTS
One hundred and twelve patients met the criteria for inclusion. 69% received their surgical intervention in the first three months after implantation ('early') and 21% after 12 months. Overall the most frequently isolated organisms were coagulase negative staphylococci (47% patients) and methicillin-sensitive Staphylococcus aureus (MSSA, 44% patients). 8% grew methicillin-resistant Staphylococcus aureus (MRSA) and 7% grew anaerobes. Most Gram-negative isolates were resistant to cefuroxime; all were sensitive to meropenem. Eighty-six percent of polymicrobial cultures occurred in early infections when 47% of patients grew more than one organism. MSSA was the most frequently isolated organism at all time points.


CONCLUSIONS
Most infections involved staphylococci. MRSA was infrequently isolated. Most polymicrobial infections occurred in early infection. A high rate of resistance to cephalosporins among Gram-negative organisms justifies the use of a broader agent such as a carbapenem in the early empirical antibiotic regime for PJI.
Moran
E
E
Department of Microbiology and Infectious Disease, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK. ed@moran.org
Masters
S
S
Berendt
A R
AR
McLardy-Smith
P
P
Byren
I
I
Atkins
B L
BL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D019643:Arthroplasty, Replacement / Q000009:adverse effects*; D003646:Debridement; D005260:Female; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D007595:Joint Prosthesis / Q000009:adverse effects*; D007720:Knee Prosthesis / Q000009:adverse effects; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000188:drug therapy* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D007507:Therapeutic Irrigation
D000900:Anti-Bacterial Agents