Surgical treatment
The median number of debridement operations per patient
was three (range one to six). All debridements were
performed by open arthrotomy and involved a change of
the polyethylene liner, removal of infected soft tissue and
washout of the joint under high-pressure pulsatile lavage.
There were no major surgical complications noted as a
consequence of the debridement operations
Medical treatment
All patients in the study population received an initial
course of intravenous antibiotics followed by oral antibiotictherapy. The median duration of intravenous antibiotic
treatment was 40 days (range 9–79 days). The intravenous
antibiotic used for treatment of the Gram-negative infection
was a second- or third-generation cephalosporin in 11
patients, meropenem in seven patients and ertapenem in
three patients. Nine patients in addition received intravenous
vancomycin for initial treatment of mixed infections
with staphylococci and three patients received intravenous
benzylpenicillin for treatment of mixed infections with
enterococci. The median duration of inpatient hospital stay
for treatment of the infection was 23 days (range 9–
57 days). Two patients experienced a rash while receiving
intravenous antibiotics, leading to an earlier change to oral
antibiotics. The median duration of oral antibiotic treatment
was 12 months (range 1–55 months). Ciprofloxacin
was used for oral treatment of the Gram-negative infection
in 14 patients and amoxycillin/clavulanic acid was used in
three patients. Rifampicin-based oral regimens were used
in addition for mixed staphylococcal infections in ninepatients.
Three patients experienced transient nausea while taking
oral antibiotics; however, treatment was continued in each
of these. In another three patients, oral antibiotic treatment
was modified or shortened because of side effects or noncompliance.
In two patients, the oral antibiotic treatment is
ongoing with the intention of long-term suppression.
Follow-up
The median duration of follow-up was 28 months (range 2–
99 months) from the time of infection. The median time of
follow-up after stopping antibiotics was 12 months. One
patient died from unrelated causes 2 months after infection.
Outcomes
All 17 patients retained the original prosthesis at the time of
last review. There was no evidence of treatment failure in 15
patients. The 2-year survival rate free of treatment failure
was 94% (95% CI, 63–99%). One patient (patient 1) with a
mixed Klebsiella pneumoniae and methicillin-resistant Staphylococcus
epidermidis hip prosthesis infection developed relapsed
Klebsiella pneumoniae infection 6 years later. Staphylococcus
epidermidis was not isolated at the time of relapse. This
patient had been treated with 7 weeks of intravenous ceftriaxone
and then oral amoxicillin/clavulanic acid, rifampicin and
fusidic acid but was non-compliant with the oral antibiotics
after 4 months. Another patient (patient 11), with a mixed
methicillin-resistant Staphylococcus aureus (MRSA), E. coli and
Proteus mirabilis hip prosthesis infection, developed relapsed
MRSA infection 6 months after ceasing antibiotic therapy and
in the setting of new immunosuppression for myasthenia gravis.
Neither E. coli nor Proteus mirabilis were isolated at the
time of relapse. The relapsed infection was treated with further
debridement and the patient remained well on followup
while taking long-term suppressive oral antibiotics for the
MRSA infection.