Outcome and predictors of treatment failure in total hip/knee prosthetic joint infections due to Staphylococcus aureus.

BACKGROUND: Variables associated with the outcome of patients treated for prosthetic joint infections (PJIs) due to Staphylococcus aureus are not well known. METHODS: The medical records of patients treated surgically for total hip or knee prosthesis infection due to S. aureus were reviewed. Remission was defined by the absence of local or systemic signs of implant-related infection assessed during the most recent contact with the patient. RESULTS: After a mean posttreatment follow-up period of 43.6 ± 32.1 months, 77 (78.6%) of 98 patients were in remission. Retention of the infected implants was not associated with a worse outcome than was their removal. Methicillin-resistant S. aureus (MRSA)-related PJIs were not associated with worse outcome, compared with methicillin-susceptible S. aureus (MSSA)-related PJIs. Pathogens identified during revision for failure exhibited no acquired resistance to antibiotics used as definitive therapy, in particular rifampin. In univariate analysis, parameters that differed between patients whose treatment did or did not fail were: American Society of Anesthesiologists (ASA) score, prescription of adequate empirical postsurgical antibiotic therapy, and use of rifampin combination therapy upon discharge from hospital. In multivariate analysis, ASA score ≤2 (odds ratio [OR], 6.87 [95% confidence interval {CI}, 1.45-32.45]; P = .04) and rifampin-fluoroquinolone combination therapy (OR, 0.40 [95% CI, 0.17-0.97]; P = .01) were 2 independent variables associated with remission. CONCLUSIONS: The results of the present study suggest that the ASA score significantly affects the outcome of patients treated for total hip and knee prosthetic infections due to MSSA or MRSA and that rifampin combination therapy is associated with a better outcome for these patients when compared with other antibiotic regimens.

Tolerability of prolonged linezolid therapy in bone and joint infection: protective effect of rifampicin on the occurrence of anaemia?

BACKGROUND: Linezolid therapy has shown high rates of clinical success in patients with osteomyelitis and prosthetic joint infections caused by Gram-positive cocci. Recent studies have demonstrated that linezolid/rifampicin combination therapy prevents the emergence of rifampicin-resistant mutations in vitro. However, linezolid/rifampicin combination-related haematological and neurological toxicities have not been evaluated. OBJECTIVES: To assess the tolerability of prolonged linezolid/rifampicin combination therapy compared with other linezolid-containing regimens in patients with bone and joint infections. METHODS: We reviewed the medical records of 94 patients who had received linezolid for >4 weeks after bone and joint infections. Anaemia was defined as a ≥2 g/dL reduction in haemoglobin, leucopenia as a total leucocyte count <4 × 10(9)/L, and thrombocytopenia as a reduction in platelet count to <75% of baseline. RESULTS: Anaemia was less frequent among patients on linezolid/rifampicin combination therapy than among patients on linezolid alone or in combination with other drugs (9.3%, 44% and 52%, respectively; P<0.01). In multivariate analysis, age and treatment group were independently associated with anaemia. Thrombocytopenia was reported in 44% of patients on linezolid/rifampicin combination therapy, in 48% of patients on linezolid alone and in 57.7% of patients on other linezolid-containing regimens. Age was the only variable associated with thrombocytopenia (P=0.019) in univariate analysis. CONCLUSIONS: Linezolid/rifampicin combination therapy was associated with a significantly reduced incidence of anaemia among patients with bone and joint infections, but it did not have an effect on thrombocytopenia and peripheral neuropathy rates. Linezolid/rifampicin combination therapy was not associated with poor clinical outcomes.

Needle puncture and transcutaneous bone biopsy cultures are inconsistent in patients with diabetes and suspected osteomyelitis of the foot.

BACKGROUND: Needle puncture has been suggested as a method for identifying bacteria in the bones in patients with diabetes with osteomyelitis of the foot. However, no studies have compared needle puncture with concomitant transcutaneous bone biopsy, which is the current standard recommended in international guidelines. METHODS: We conducted a prospective study in 2 French diabetes foot clinics. Transcutaneous bone biopsy specimens, needle puncture specimens, and swab samples were collected on the same day for each patient. RESULTS: Overall, 31 patients were included in the study from July 2006 through February 2008. Twenty-one bone biopsy specimens (67.7%), 18 needle puncture specimens (58%), and 30 swab samples (96.7%) had positive culture results. Staphylococcus aureus was the most common type of bacteria that grew from bone samples, followed by Proteus mirabilis and Morganella morganii. The mean number of bacteria types per positive sample were 1.35, 1.32, and 2.51 for bone biopsy specimens, needle puncture specimens, and swab samples, respectively. Among the 20 patients with positive bone biopsy specimens (69%), 13 had positive needle puncture samples. Overall, the correlation between microbiological results was 23.9%, with S. aureus showing the strongest correlation (46.7%). Results of cultures of bone biopsy and needle puncture specimens were identical for 10 (32.3%) of 31 patients. Bone bacteria were isolated from the needle punctures in 7 (33.3%) of the 21 patients who had positive bone biopsy specimen culture results. If the results of cultures of needle puncture specimens alone had been considered, 5 patients (16.1%) would have received unnecessary treatment, and 8 patients (38.1%) who had positive bone culture results would not have been treated at all. CONCLUSIONS: Our results suggest that needle punctures, compared with transcutaneous bone biopsies, do not identify bone bacteria reliably in patients with diabetes who have low-grade infection of the foot and suspected osteomyelitis.

Effectiveness and tolerability of prolonged linezolid treatment for chronic osteomyelitis: a retrospective study.

BACKGROUND: Linezolid is an oxazolidinone agent which is apparently well designed for treating chronic osteomyelitis, but data on effectiveness and tolerability as prolonged therapy is currently lacking. OBJECTIVE: The purpose of this study was to assess the effectiveness and tolerability of linezolid in the treatment of chronic osteomyelitis. METHODS: The charts of hospitalized patients who had been treated with linezolid for >4 weeks because of chronic osteomyelitis and were followed up for > or =12 months after the end of treatment were retrospectively reviewed for clinical outcome and tolerability. Cure was defined as the absence of clinical, biological, or radiological evidence of infection throughout the posttreatment follow-up. Linezolid tolerability was assessed on the basis of hematologic properties during treatment. RESULTS: Of the 66 patients included, all were white (mean [SD] age, 67.7 [18.1] years; 41 men and 25 women; mean [SD] weight, 80.7 [18.6] kg). Thirty-seven (56.1%) patients had infection due to implants including 27 prosthetic joints. Pathogens were predominantly methicillin-resistant staphylococci (49/72 strains, 68.1 %). Every patient was administered N linezolid (600 mg BID) treatment for 6 to 8 days as inpatients, and then, as outpatients, they were switched to PO treatment. Fifty (75.8%) patients received a combination of linezolid and other antimicrobial agents, including rifampin (32 [48.5%]). Surgery was performed in 52 (78.8%) patients. The median hospital stay was 14 days (mean [SD], 19 [11.4] days [range, 7-70 days] ). The median duration of treatment was 13 weeks (mean [SD], 14.3 [8.2] weeks [range, 5-36 weeks]). At the end of treatment, 56 (84.8%) patients were cured, and during the post-treatment follow-up (median duration, 15 months [range, 12-36 months]), 4 relapses occurred, resulting in an overall successful cure for 52 (78.8%) patients. Reversible anemia was reported in 21 patients (31.8%), of whom 16 (24.2%) required blood transfusions. Median time from treatment initiation to anemia onset was 7.3 weeks (range, 4-12 weeks). Peripheral neuropathy was reported in 6 (9.1%) patients, of whom 4 remained symptomatic for up to 24 months after linezolid discontinuation. Other reported adverse events included nausea (6 [9.1%]), diarrhea (1 [1.5%]), and headache (2 [3.0%]), although none of these patients discontinued treatment. CONCLUSIONS: In this retrospective chart review, treatment with linezolid as monotherapy or in combination with antimicrobials and/or surgery was associated with cure of chronic osteomyelitis in 84.8% of subjects at 12 weeks after the end of treatment and 78.8% at follow-up. Adverse events were reported in 51.5% of subjects, and 34.8% of subjects discontinued the study because of adverse events. The potential for severe complications justifies close monitoring of these patients.

Culture of percutaneous bone biopsy specimens for diagnosis of diabetic foot osteomyelitis: concordance with ulcer swab cultures.

BACKGROUND: We assessed the diagnostic value of swab cultures by comparing them with corresponding cultures of percutaneous bone biopsy specimens for patients with diabetic foot osteomyelitis. METHODS: The medical charts of patients with foot osteomyelitis who underwent a surgical percutaneous bone biopsy between January 1996 and June 2004 in a single diabetic foot clinic were reviewed. Seventy-six patients with 81 episodes of foot osteomyelitis who had positive results of culture of bone biopsy specimens and who had received no antibiotic therapy for at least 4 weeks before biopsy constituted the study population. RESULTS: Pathogens isolated from bone samples were predominantly staphylococci (52%) and gram-negative bacilli (18.4%). The distributions of microorganisms in bone and swab cultures were similar, except for coagulase-negative staphylococci, which were more prevalent in bone samples (P < .001). The results for cultures of concomitant foot ulcer swabs were available for 69 of 76 patients. The results of bone and swab cultures were identical for 12 (17.4%) of 69 patients, and bone bacteria were isolated from the corresponding swab culture in 21 (30.4%) of 69 patients. The concordance between the results of cultures of swab and of bone biopsy specimens was 42.8% for Staphylococcus aureus, 28.5% for gram-negative bacilli, and 25.8% for streptococci. The overall concordance for all isolates was 22.5%. No adverse events--such as worsening peripheral vascular disease, fracture, or biopsy-induced bone infection--were observed, but 1 patient experienced an episode of acute Charcot osteoarthropathy 4 weeks after bone biopsy was performed. CONCLUSIONS: These results suggest that superficial swab cultures do not reliably identify bone bacteria. Percutaneous bone biopsy seems to be safe for patients with diabetic foot osteomyelitis.