Increased short- and long-term mortality amongst patients with early periprosthetic knee joint infection.

BACKGROUND: Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) is a severe complication in terms of disability, morbidity, and cost. We performed a study to investigate whether early PJI (within 90 days of primary TKA) is associated with increased mortality. Secondary aims were to compare mortality rates over time and between surgical treatment methods. METHODS: Patients with suspected PJI were identified by linkage of the Swedish Knee Arthroplasty Register (SKAR) and the Swedish Prescribed Drug Register (SPDR) in 2007-2008 and 2012-2013. Medical records of patients receiving more than 4 weeks of continuous antibiotic therapy were subsequently reviewed to verify the PJI diagnosis. Information on mortality was obtained through the SKAR which is updated daily from the tax agency and patients with PJI were compared to patients without PJI. RESULTS: Four hundred sixty-six patients were diagnosed with PJI within 90 days and compared to 40,362 patients without PJI. Mortality rates were significantly higher for PJI patients in both short- and long term: 2.6% vs. 0.8% at 1 year, 4.9% vs. 1.9% at 2 years, 15.7% vs. 7.1% at 5 years, and 38% vs. 21.4% at 10 years. The difference in mortality rate remained after adjusting for sex, age, diagnosis, and time period for surgery with Hazard Ratio 1.8 (95% CI:1.6-2.1). Mortality rates did not differ between time periods, and we found no correlation to surgical treatment. CONCLUSION: Patients with early PJI after primary TKA have an increased mortality rate compared to TKA patients without PJI. Improvements in surgical treatment strategy has not resulted in better survival. Long term difference in mortality rates indicates that PJI is not the sole reason for mortality suggesting a general frailty in PJI patients.

Similar periprosthetic joint infection rates after and before a national infection control program: a study of 45,438 primary total knee arthroplasties.

Background and purpose - Strenuous efforts to minimize postoperative infection rates have been made, including the Swedish nationwide initiative Prosthesis Related Infections Shall be Stopped (PRISS). This study calculated the incidence rate of periprosthetic joint infection (PJI) following primary total knee arthroplasty (TKA) before and after PRISS. Patients and methods - All 45,438 primary TKAs registered in the Swedish Knee Arthroplasty Register (SKAR) during 2007-2008 and 2012-2013 were included. Matched data on antibiotic prescriptions were obtained from the Swedish Prescribed Drug Register (SPDR). All patients with ≥ 28 days of continuous antibiotic treatment within 2 years of primary surgery had their medical charts reviewed to identify cases of PJI. The incidence rate was calculated by dividing the number of PJIs by the total time at risk during each time period and presented as percentages with 95% confidence interval (CI). Results - 644 PJIs were identified, equaling a 2-year incidence rate of 1.45% (CI 1.34-1.57). The incidence rate was 1.44% (CI 1.27-1.61) before PRISS and 1.46% (CI 1.31-1.61) after. Diagnosis was made within 30 days of primary TKA in 52%, and within 90 days in 73% of cases. 603 cases were reoperated on or revised. Median time from operation to diagnosis was 29 days (1-716), for both time periods. Debridement with exchange of the insert was performed in 32% and 63% of cases before and after PRISS, respectively. Interpretation - We found similar incidence rates before and after the PRISS initiative without any statistically significant difference. Time to diagnosis was similar during both time periods. The project may have contributed to increased compliance with treatment protocols.

Higher risk of revision for infection using systemic clindamycin prophylaxis than with cloxacillin.

Background and purpose - Clindamycin has not been compared with other antibiotics for prophylaxis in arthroplasty. Since 2009, the Swedish Knee Arthroplasty Register (SKAR) has been collecting information on the prophylactic antibiotic regime used at every individual operation. In Sweden, when there is allergy to penicillin, clindamycin has been the recommended alternative. We examined whether there were differences in the rate of revision due to infection depending on which antibiotic was used as systemic prophylaxis. Patients and methods - Patients who had a total knee arthroplasty (TKA) performed due to osteoarthritis (OA) during the years 2009-2015 were included in the study. Information on which antibiotic was used was available for 80,018 operations (55,530 patients). Survival statistics were used to calculate the rate of revision due to infection until the end of 2015, comparing the group of patients who received cloxacillin with those who received clindamycin as systemic prophylaxis. Results - Cloxacillin was used in 90% of the cases, clindamycin in 7%, and cephalosporins in 2%. The risk of being revised due to infection was higher when clindamycin was used than when cloxacillin was used (RR =1.5, 95% CI: 1.2-2.0; p = 0.001). There was no significant difference in the revision rate for other causes (p = 0.2). Interpretation - We advise that patients reporting allergic reaction to penicillin should have their allergic history explored. In the absence of a clear history of type-I allergic reaction (e.g. urticaria, anaphylaxis, or bronchospasm), we suggest the use of a third-generation cephalosporin instead of clindamycin as perioperative prophylaxis when undergoing a TKR. No recommendation can be given regarding patients with type-1 allergy.

Prevalence and risk factors for haematogenous periprosthetic joint infection during Staphylococcus aureus bacteraemia.

BACKGROUND: Staphylococcus aureus bacteraemia (SAB) may lead to periprosthetic joint infections (PJI) via haematogenous spread of bacteria to the joint. Due to the risk of PJI, patients with SAB and prosthetic joint are recommended prolonged antibiotic treatment. The aim of the study was to assess the risk of PJI during SAB, and to evaluate if short treatment duration affects outcomes in patients with uncomplicated SAB and prosthetic joints without clinical signs of PJI. METHODS: Patients with growth of S. aureus in blood cultures were cross-referenced against the Swedish Arthroplasty register to identify patients with prosthetic hip or knee joints at the time of SAB. Medical records were reviewed to identify PJI at the time of SAB and during a 6-month follow-up period. RESULTS: Out of 400 patients with SAB and a prosthetic joint, 281 met all eligibility criteria and were included in the study. Of the included participants, 35 (12%) had a haematogenous PJI. Younger age and presence of multiple prosthetic joints were associated with an increased risk of PJI. Of the 247 patients without signs of PJI at the initial SAB episode, 118 patients (48%) had an uncomplicated infection and received short total antibiotic treatment (median 15 days, IQR 13-17). The risk of PJI during the follow-up period was low (<1%) and similar in the uncomplicated group compared to patients with complicated SAB that received longer antibiotic treatment (median 29 days, IQR 15-70). CONCLUSION: The prevalence of haematogenous PJI was lower than previously reported. Our data do not support prolonged antibiotic treatment in patients with SAB and prosthetic joints without clinical signs of PJI.

Biofilm formation is associated with poor outcome in prosthetic joint infections caused by Staphylococcus lugdunensis.

BACKGROUND: Staphylococcus lugdunensis has been described as a pathogen of increasing importance in prosthetic joint infections (PJI). Our aim was to describe the clinical presentation of PJI caused by S. lugdunensis, and to correlate the biofilm-forming ability of the bacterial isolates to clinical outcome. METHOD: S. lugdunensis isolates from PJI episodes during 2015-2019 were included and analysed for biofilm formation using a microtiter plate assay. Medical records from the corresponding patients were reviewed. RESULTS: We identified 36 patients with PJI caused by S. lugdunensis during the study period. Early postoperative PJIs were most frequent (n = 20, 56%). Surgical intervention was performed in a majority of the patients (n = 33, 92%), and the dominating type of antibiotic treatment was a combination of rifampicin and ciprofloxacin (n = 27, 75%). The treatment success-rate was 81% (n = 29). All isolates causing PJI were able to form biofilm in vitro. Biofilm formation was significantly stronger in isolates causing relapsing vs non-relapsing PJI (mean OD550 3.1 ± 0.23 vs 1.14 ± 0.73 p = .001) and strong biofilm formation was also associated with late acute hematogenic PJI (mean OD550 1.8 ± 0.93 vs. 0.93 ± 0.81, p = .01). CONCLUSION: Strong biofilm production in S. lugdunensis isolates was associated with relapse in PJI.

A population-based study on the treatment and outcome of enterococcal prosthetic joint infections. A consecutive series of 55 cases.

AIM: Enterococci cause 2-11% of all prosthetic joint infections (PJI) and are generally considered difficult to treat. However, study-results are not consistent. In this study we present a population-based case series of 55 cases with enterococcal PJI, investigating treatment and outcome, as well as describing the affected patient population regarding demography and co-morbidities. METHODS: We identified all enterococcal PJIs in the Region of Skåne, Sweden, during a five-year period (2011-2015) and reviewed the patients' medical records. RESULTS: Fifty-five enterococcal PJIs were found. Enterococcus faecalis was the most frequently isolated species (84%), and poly-microbial infections were common (64%). Treatment with intention to cure was given to 43 (78%) cases. Debridement with retention of the implant and antibiotics (DAIR) was the most common surgical treatment strategy (71%), with a cure-rate of 72%. Overall cure-rate was 67%, and in cases where cure was intended, this was achieved in 80%. CONCLUSIONS: When cure is aimed for, the prognosis for enterococcal PJI is not so poor, and DAIR treatment can provide adequate results in many cases.

Successful outcome for patients with streptococcal prosthetic joint infections - a retrospective population-based study.

BACKGROUND/AIM: Streptococci cause approximately 10% of prosthetic joint infections (PJIs). The aim of this study was to identify the characteristics of patients with streptococcal PJIs and to describe the treatment and outcome of streptococcal PJIs in Skåne county between 2011 and 2015. METHODS: Patients with streptococcal PJIs with positive cultures or PCRs on samples from joint aspirate and/or periprosthetic tissue between 2011 and 2015 in Skåne county, were identified and medical records were studied. RESULTS: Eighty-three PJI episodes treated at seven hospitals were identified. The median age was 70 years (IQR: 64-78) and there were more men (61%) than women. Hip joints were the most common site of isolation (54%). The most frequently isolated pathogens were beta-haemolytic streptococci of groups A, C and G (31%), group B (30%), and alpha-haemolytic streptococci (23%). Overall failure rate was 11% (n = 9), and lack of comorbidity was significantly associated with a favourable outcome. The most common treatment strategy was debridement, antibiotic treatment and implant retention (DAIR) (n = 64; 77%) and the initial success rate using this strategy was 84% (n = 53). CONCLUSION: This study indicates an acceptable success rate for the patients treated with DAIR strategy, and a high overall success rate for episodes suffering streptococcal PJIs.

A study on the outcome of percutaneous transluminal renal angioplasty in patients with renal failure.

BACKGROUND: The indications for percutaneous transluminal renal angioplasty (PTRA) in renovascular disease, as well as its benefits, remain a matter of debate. The aim of this study was to evaluate the outcome of angioplasty and to identify risk factors associated with less successful outcomes in patients with atheromatous renal artery stenosis and renal failure of varying degrees. METHODS: The results of PTRA were analyzed retrospectively in 144 patients with serum creatinine levels of >130 micromol/l. Patients were divided into 5 groups according to their indication for angioplasty: (1) deteriorating renal function; (2) accelerating hypertension; (3) a combination of 1 and 2; (4) peripheral vascular disease, and (5) miscellaneous conditions. RESULTS: The baseline mean (+/- SD) systolic and diastolic blood pressures of the entire group were lowered from 180 +/- 32 and 95 +/- 16 mm Hg to 162 +/- 23 and 86 +/- 12 mm Hg, respectively (p < 0.0005), 12 months after angioplasty. The blood pressure level was unaffected by angioplasty in patients with claudication. The mean number of antihypertensive drugs was reduced in the group with accelerating hypertension from 2.9 +/- 0.8 to 2.4 +/- 1.2 (p = 0.019), and in the group with unilateral renal artery stenosis and two kidneys from 2.4 +/- 1.0 to 1.8 +/- 1.1 (p = 0.002), 12 months after PTRA. Glomerular filtration rate at 3-month follow-up had increased from 23 +/- 11 to 27 +/- 14 ml/min/1.73 m(2) (p = 0.021) in group 1, from 25 +/- 11 to 28 +/- 14 ml/min/1.73 m(2) (p = 0.031) in the combined group of patients consisting of groups 1 and 3, and from 32 +/- 13 to 35 +/- 14 ml/min/1.73 m(2) (p = 0.019) in the group with unilateral renal artery stenosis. No statistically significant difference was found in any of these 3 groups 1 year after angioplasty. The first patient group had an increased prevalence of cardiovascular disease, aortic aneurysm, carotid occlusive disease, and peripheral vascular disease compared to the other patient groups (p < 0.05). Patients with baseline creatinine levels of >300 micromol/l had a lower survival rate at 12, 60, and 120 months after PTRA than patients with serum creatinine levels of <300 micromol/l (p < 0.005). Survival was also lower in patients with bilateral renal artery stenosis and those with a single kidney, compared to patients with a unilateral stenosis at both 5 and 10 years after PTRA (p < 0.05). Regression analysis of predictor variables of mortality rate showed that the relative risk (RR) associated with increased serum creatinine was 4.7 (CI 2.0-11.0; p < 0.0005). The RR for older patients was 1.1 (CI 1.0-1.2; p = 0.008), and the RR for former smokers was 6.0 (CI 1.6-24.0; p = 0.009). CONCLUSION: The results of the present study indicate that glomerular filtration can be improved in patients who primarily undergo angioplasty to rescue renal function. Renal function with creatinine levels of >300 micromol/l was associated with a lower survival rate. It is, therefore, possible that patients selected after a thorough evaluation of their renal function and comorbid disease factors may benefit from PTRA, even when the indication for angioplasty is to salvage renal function.