Elution Profiles of Synthetic CaSO4 Hemihydrate Beads Loaded with Vancomycin and Tobramycin

Antibiotic-Loaded Calcium Sulphate Beads for Treatment of Acute Periprosthetic Joint Infection in Total Knee Arthroplasty: Results Based on Risk Stratification

Background: A post-operative or late acute periprosthetic joint infection (PJI) after Total Knee Arthroplasty (TKA) requires a protocol of aggressive joint Debridement, modular implant Exchange, Component Retention, and post-operative Antimicrobial therapy (DECRA). Recently, the novel addition of intra-articular Antimicrobial Loaded Calcium Sulphate (AL-CaSO4) beads during DECRA has been utilized to improve microbial eradication. This study reviews a consecutive series of DECRA TKA procedures with AL-CaSO4 beads with a standardized antimicrobial regimen. We hypothesize AL-CaSO4 beads will not improve infection-free implant survival in compromised hosts and limbs. Methods: This consecutive series included DECRA procedures for acute post-operative or late hematogenous PJI-TKA (primary and revision) detected within 4 weeks. One gram of vancomycin powder and 240 mg of liquid tobramycin were added to 10 cc of CaSO4 powder to create 3.0 and 4.8 mm beads delivered into the joint at closure. All patients were risk stratified according to McPherson Staging and followed for a minimum of 1 year. Results: Forty-two patients were studied. The infection-free success rate of DECRA with AL-CaSO4 was 62% (26/42) at 1 year. Average bead volume per case was 18.6 cc (range = 10-40 cc). McPherson Host stage and Limb Score were found to be significantly correlated with the success of the DECRA (p < 0.05). The success rate was highest in A-hosts (87.5%), declining to 50% in B-hosts, and 25% in C-hosts. Similarly, the success rate was highest for patients with Limb score 1 (100%), declining to 58.6% with Limb score 2, and 20% with Limb score 3. Importantly, a previous episode of infection in the affected joint was associated with significantly increased failure (p = 0.000025). Conclusions: This study reports an overall higher infection-free success rate of DECRA using AL-CaSO4 beads compared to the current literature. Antibiotic beads provide an advantage in selected groups that include A or B hosts and Limb scores of 1 or 2. In C-hosts, where the immune system is weak, or Limb score 3, where the wound is compromised and leaks, antibiotic beads do not improve success. Importantly, DECRAs should not be considered curative with a prior history of joint infection. In these difficult circumstances, one should consider an exchange protocol.

Vascular Graft Infections Treated With Bioabsorbable Antibiotic Beads

INTRODUCTION

Inguinal vascular surgical site infections (VSSI) and infected prosthetic grafts remain a critical problem in vascular surgery. Prior clinical reports suggest antibiotic-impregnated beads may be used to attempt salvage of the graft and improve outcomes, especially if explant would result in major amputation or mortality. Described is our institutional experience managing inguinal VSSI using bioabsorbable, antibiotic-impregnated beads compared to inguinal VSSI managed with debridement alone.

METHODS

Patients with VSSIs after lower-extremity procedures were identified through the institutional database and departmental registries from 2014 to 2023. Cases were excluded if they did not involve an inguinal wound infection or an operation for VSSI management. Outcomes, including amputation-free survival, reinfection, and re-operation for infection were recorded, along with microbial isolates. Basic descriptive statistics, Kaplan-Meier, and Multiple variable Cox proportional hazards analyses were performed.

RESULTS

There were 43 patients identified (23 with intravenous antibiotics and debridement alone, and 20 treated with intravenous antibiotics, debridement, and antibiotic beads). The two groups differed significantly in their Szilagyi classification, with thirteen patients (65%) with class III infections in the antibiotic bead group compared with one (7%) in the debridement alone group. There was no significant difference in amputation-free survival for those cases that received debridement and antibiotic beads versus debridement alone (P = 0.20) or amputation-free survival between Szilagyi classifications (P = 0.47) despite a higher representation of Szilagyi III cases in the antibiotic bead group (P = 0.0001). Patients with graft infections treated with beads experienced similar survival outcomes to patients with subcutaneous infections treated with debridement alone (P = 0.21).

CONCLUSIONS

The efficacy of bioabsorbable antibiotic beads in VSSIs remains controversial. While this cohort study demonstrated an increased risk of re-infection, this is confounded by the antibiotic bead group having a higher frequency of graft infections. Antibiotic beads appear to be safe for use in patients with vascular graft infections and may help achieve outcomes comparable to patients without graft involvement. Further studies with larger patient populations and similar infection severity between groups are needed.

Expedited infection control and wound healing by combining Matriderm®, a dermal matrix, and Stimulan® absorbable antibiotic beads: a case report

Background

Since dermal matrices (DMs) were first described in surgery, they have become an integral part of the reconstructive ladder, providing plastic surgeons with new approaches to wound reconstruction. While they have been used in reconstruction of a wide range of wounds, there has been limited or no literature on their effects when used in conjunction with fully absorbable antibiotic beads. Therefore, the aim of this study was to analyze the effects of using Matriderm® dermal matrix concurrently with Stimulan® absorbable antibiotic beads on wound healing and readiness for skin grafting.

Case Description

In this manuscript, we report the case of an adult ethnic Chinese male patient with recalcitrant infected right lower limb fasciotomy wounds managed using Matriderm® dermal matrix in conjunction with Stimulan® absorbable antibiotic beads prior to split-thickness skin graft reconstruction. The patient was a non-smoker with no known comorbid medical conditions and had initially presented with right lower limb compartment syndrome and rhabdomyolysis following a fall with long lie. He subsequently underwent an emergency fasciotomy with resulting medial and lateral right lower limb fasciotomy wounds. In this case report, wound revascularization, granulation formation and readiness for skin grafting were observed after one week of concurrent application of Matriderm® and Stimulan®. The patient's post-operative recovery was uneventful and he was discharged eleven days post skin grafting. There was at least 97% graft uptake and the graft donor site had healed well and was left exposed.

Conclusions

The application of DMs in conjunction with absorbable antibiotic beads may shorten time to readiness for definitive wound coverage. Further randomized controlled trials are required to evaluate this potentially synergistic relationship.

Effects of storage up to 1 year on the in vitro antimicrobial activity of preformulated antibiotic-impregnated calcium sulfate beads

OBJECTIVE

To compare antimicrobial activity as demonstrated by the zone of inhibition (ZOI) produced by antibiotic-impregnated calcium sulfate (CaSO4) beads after storage for 0, 3, 6, 9, and 12 months.

STUDY DESIGN

Controlled laboratory study.

SAMPLE POPULATION

Three-millimeter diameter CaSO4 beads impregnated with vancomycin (125 mg/mL), or amikacin (250 mg/mL), or without antibiotic (control).

METHODS

Calcium sulfate beads were created at the onset of the study. Individual beads were separated in sterile containers and stored in a closed cabinet at room temperature and humidity for 0, 3, 6, 9, or 12 months until testing. The ZOI against methicillin-resistant Staphylococcus pseudintermedius, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa was recorded with serial replating on a fresh lawn of bacteria every 24 h until beads failed to produce a ZOI. The ZOIs and their changes were compared with mixed-effects linear models. Eluted concentrations of vancomycin measured with high-performance liquid chromatography were reported.

RESULTS

At 24 h, ZOIs were comparable regardless of time since formulation, except vancomycin against P. aeruginosa, which failed to generate a ZOI. The daily changes of ZOI and duration of activity of antibiotics did not vary between storage length (p > .05). There was no consistent change in eluted drug concentration between storage length of beads.

CONCLUSION

Light protected storage at room temperature for up to 12 months did not impair the in vitro activity of antibiotic-impregnated CaSO4 beads, as demonstrated through ZOIs.

CLINICAL SIGNIFICANCE

When stored correctly, antibiotic-impregnated CaSO4 beads can be used at least up to 12 months after formulation.

Are Biodegradable Calcium Sulfate Antibiotic Beads Effective and Safe Adjuvants for Diabetic Foot Osteomyelitis?

INTRODUCTION

 Diabetic foot osteomyelitis (DFO) is a highly morbid condition that commonly affects diabetic patients. Biodegradable calcium-sulfate antibiotic beads (CaSO4) are theoretical adjuvant agents to reduce morbidity in DFO. However, there is a paucity of research on the safety and effectiveness of CaSO4 beads in DFO. Therefore, the purpose of this study was to assess the safety and effectiveness of CaSO4 beads in different DFO locations.

METHODS

We conducted a retrospective cohort study between January 1, 2015 and January 1, 2022 of patients with DFO who underwent surgical intervention and adjuvant CaSO4 beads placement. The location of DFO was determined based on the forefoot, midfoot, or hindfoot locations. Outcomes measured were ulcer-free time points of three and six months as well as recurrence of DFO at 12 months. Safety was also evaluated with incidences of acute kidney injury, wound drainage, and hypercalcemia.

RESULTS

Forty-five cases were included. Of these, only 9/45 (20%) and 13/45 (29%) were ulcer-free at three months and six months, respectively. DFO recurred in 19/45 (42%) patients. Safety outcomes were significant for wound drainage (62%) and acute kidney injury (9%). Stratifying according to the location of DFO showed no statistically significant difference in outcomes.

CONCLUSION

In this cohort study, adjuvant CaSO4 beads showed high rates of ulcer persistence and DFO recurrence. Given the limited benefits seen here and the potential for high rates of wound drainage, the use of adjuvant CaSO4 beads should be used cautiously until a multicenter randomized clinical trial is conducted to definitely evaluate the safety and effectiveness of CaSO4 beads in DFO.

The stability of Staphylococcal bacteriophage in presence of local vancomycin concentrations used in clinical practice

PURPOSE

To evaluate the stability of a clinically used Staphylococcal bacteriophage with doses of vancomycin that are encountered with local administration of vancomycin for musculoskeletal infections.

METHODS

A Staphylococcal bacteriophage was evaluated for stability in different pH ranges. Then that same bacteriophage was evaluated for stability with different concentrations of vancomycin and with vancomycin biodegradable antibiotic beads.

RESULTS

The bacteriophage had stability within a pH range of 4-10. There was a statistically significant (P < 0.05) decrease in the amount of bacteriophage over 24 h for vancomycin concentrations of 10 mg/mL and 100 mg/mL compared to lower vancomycin concentrations (1 mg/mL, 0.1 mg/mL and normal saline). However, no statistically significant decrease in the amount of bacteriophage was seen with biodegradable vancomycin beads over 24 h.

CONCLUSION

These findings have important clinical ramifications in that they show local administration of bacteriophages with concomitant local vancomycin powder therapy should be avoided. Moreover, these findings should spearhead further research into bacteriophage stability in in vivo environments.

The use of Stimulan in bone and joint infections

Aims

Musculoskeletal infection is a devastating complication in both trauma and elective orthopaedic surgeries that can result in significant morbidity. Aim of this study was to assess the effectiveness and complications of local antibiotic impregnated dissolvable synthetic calcium sulphate beads (Stimulan Rapid Cure) in the hands of different surgeons from multiple centres in surgically managed bone and joint infections.

Methods

Between January 2019 and December 2022, 106 patients with bone and joint infections were treated by five surgeons in five hospitals. Surgical debridement and calcium sulphate bead insertion was performed for local elution of antibiotics in high concentration. In all, 100 patients were available for follow-up at regular intervals. Choice of antibiotic was tailor made for each patient in consultation with microbiologist based on the organism grown on culture and the sensitivity. In majority of our cases, we used a combination of vancomycin and culture sensitive heat stable antibiotic after a thorough debridement of the site. Primary wound closure was achieved in 99 patients and a split skin graft closure was done in one patient. Mean follow-up was 20 months (12 to 30).

Results

Overall, six out of 106 patients (5.6%) presented with sepsis and poorly controlled comorbid conditions, and died in the hospital within few days of index surgery. Out of the remaining 100 patients, control of infection was achieved in 95 patients (95%). Persistence of infection was noted in five (5%) patients. Out of these 95 patients that had good control of infection, four patients (4.2%) with gap nonunion needed Masquelet procedure to achieve union.

Conclusion

Our multicentre experience confirmed that surgical debridement along with calcium sulphate bead insertion was effective in treating bone and joint infections without any side effects and complications.

Hypercalcemia Secondary to Antibiotic-Eluting Calcium Sulfate Beads

The use of calcium sulfate beads (CSBs) as a carrier for local delivery of antibiotics is increasingly reported for the treatment of localized infections. They are used most commonly in bone and joint infections, post-trauma infections, diabetes-related foot wounds, and vascular grafts. Hypercalcemia is rarely reported with CSB use but is an important safety concern, and patients at higher risk should be identified prospectively and followed carefully postoperatively. This case report details an 85-year-old male who developed severe, symptomatic postoperative hypercalcemia after antibiotic bead placement in the right knee. He presented with confusion, weakness, and lethargy, and was subsequently treated with fluids, calcitonin, and alendronate. The patient quickly returned to normal mental status, and calcium levels normalized, leading to discharge. The case report and review of the literature describe an incident of severe hypercalcemia attributed to the use of antibiotic-eluting CSBs and describe the risk factors and time course that may be expected.

New bone formation using antibiotic-loaded calcium sulfate beads in bone transports for the treatment of long-bone osteomyelitis

PURPOSE

Bone transport is one of the most frequently used techniques for critical-sized bone defects due to trauma or infection. To fill the defect area and avoid the collapse of soft tissues during transport, some authors have described the use of polymethylmethacrylate or absorbable antibiotic carriers in the form of cylindrical blocks.

METHODS

In this article, we present our experience in the treatment of post-traumatic osteomyelitis of the lower and upper limbs, using a bone transport technique with antibiotic-loaded calcium sulfate in the form of beads. Results With the progressive absorption of calcium sulfate, we observed the formation of a bone-like tissue envelope at the periphery of the defect area. Histological analysis and direct visualization during open revision surgery of the docking site in all patients confirmed the presence of newly formed bone tissue with a high presence of osteoblasts and few osteoclasts; no areas of necrosis or signs of infection were observed. This bone envelope maintained the mechanical protective function of the transport path and docking site, and also provided a biological stimulus to avoid the development of necrotic areas and optimize the consolidation phase. Conclusion Bone transport with calcium sulfate beads improves biological and mechanical support and reduces the number of surgeries required.

Assessing tobramycin levels and renal function following the implantation of CaSO4 beads impregnated with tobramycin: A prospective cohort study

This study aimed to evaluate the risk of serum tobramycin concentrations exceeding therapeutic levels after administration of calcium sulfate (CaSO4) beads containing either 240 mg or 400 mg tobramycin and 1000 mg vancomycin. This single-center, prospective. This single-center, prospective study included included Piedmont Columbus, Regional orthopedic surgery patients. Following the implantation of tobramycin into CaSO4 beads, serially measured serum tobramycin concentrations were evaluated after 6, 12, 24, and 48 hours. In addition to that, serum tobramycin concentration was evaluated after 5 days. None of the patients who received 240 mg tobramycin-impregnated beads had a tobramycin level >2 μg/mL. Six hours after implantation, the tobramycin level in 2 out of 2 (100%) patients who received 400 mg of tobramycin-impregnated beads was >2 μg/mL. One day following the surgery, the median serum creatinine was 0.85 mg/dL, with an interquartile range of 0.73 to 1.04 mg/dL. No cases of acute kidney injury were observed. This cohort demonstrated that non-nephrotoxic serum tobramycin levels could be achieved in CaSO4 beads mixed with 240 mg or 400 mg of tobramycin.

Can Amoxicillin and Clavulanic Acid Impregnated Plaster of Paris Beads Serve as an Effective Alternative to Systemic Antibiotics for Third Molar Surgeries? A Split Mouth Randomized Clinical Trial

Purpose

The present work was a pilot study undertaken to evaluate the effectiveness of amoxicillin and clavulanic acid impregnated plaster of paris beads for prevention of infection of third molar extraction sockets.

Materials and Methods

This was a prospective, randomized, split mouth clinical trial done on 16 patients (32 sites) who required surgical extraction of mandibular third molars. Control arm patients were given Tab. amoxicillin 500 mg with clavulanic acid 125 mg (Tab. Klavimed 625 mg, Indomed, India), thrice daily for 3 days after extraction, whereas test arm patients received Antibiotic Impregnated Microbeads (AIM), containing Amoxicillin 500 mg and Clavulanic Acid 100 mg placed in situ in the extraction socket. The primary outcome parameter was infection and the secondary outcome parameters were pain, trismus, swelling and wound healing.

Results

None of the patients in either group had post operative infection. There was no significant difference in pain intensity between the two groups (1st day p = 0.41; 3rd day p = 0.38, 7th day p = 0.37). Both the groups were also similar with respect to swelling (p = 0.596, 0.146, 0.871, 0.820 on 1st, 3rd, 7th, 15th post-op day ,respectively).

Conclusion

Amoxycillin with clavulanic acid impregnated PoP beads appears to be as effective as oral 3 day amoxicillin with clavulanic acid regime for prevention of 3 M socket infection.

Simulated large joint fluid model for evaluating intra-articular antibiotic delivery systems: initial evaluation using antibiotic-loaded calcium sulfate beads

Introduction: Local antimicrobial delivery via calcium sulfate (CaSO4) beads is used as an adjunctive treatment for periprosthetic joint infection. There is limited clinical information describing the performance of antimicrobial-loaded CaSO4 (ALCS) in large-scale applications. We developed a simulated large joint model to study properties of eluting ALCS. Methods: The in vitro testing platform was an adapted standardized model for tribological testing of prosthetic total hips and total knees (ASTM F732). The model was 70 mL total fluid volume, 25 % bovine serum, and 75 % phosphate-buffered saline, using ISO standard 14242-1 for human synovial fluid simulation. Four brands of CaSO4 were evaluated. Each 10 mL of CaSO4 was loaded with 1.2 grams (g) of tobramycin and 1 g of vancomycin powders. A 35 mL bead volume, equaling 175 beads, of each product was placed in incubated flasks. The test period was 6 weeks with scheduled interval fluid exchanges. Fluid samples were tested for antibiotic and calcium concentrations and pH. Results: Antibiotic elution showed an initial burst on Day 1, followed by a logarithmic reduction over 1 week. Tobramycin fully eluted within 2.5 weeks. Vancomycin showed sustained release over 6 weeks. Calcium ion concentrations were high, with gradual decrease after 3 weeks. All four CaSO4 products were inherently acidic. Fluid became more acidic with the addition of antibiotics primarily driven by vancomycin. Discussion: Clinicians should be cognizant of tobramycin elution burst with ALCS in large loads. The main driver of acidic pH levels was vancomycin. We propose that joint complications may result from lowered fluid acidity, and we suggest clinical study of synovial pH.

Role of Implantable Drug Delivery Devices with Dual Platform Capabilities in the Prevention and Treatment of Bacterial Osteomyelitis

As medicine advances and physicians are able to provide patients with innovative solutions, including placement of temporary or permanent medical devices that drastically improve quality of life of the patient, there is the persistent, recurring problem of chronic bacterial infection, including osteomyelitis. Osteomyelitis can manifest as a result of traumatic or contaminated wounds or implant-associated infections. This bacterial infection can persist as a result of inadequate treatment regimens or the presence of biofilm on implanted medical devices. One strategy to mitigate these concerns is the use of implantable medical devices that simultaneously act as local drug delivery devices (DDDs). This classification of device has the potential to prevent or aid in clearing chronic bacterial infection by delivering effective doses of antibiotics to the area of interest and can be engineered to simultaneously aid in tissue regeneration. This review will provide a background on bacterial infection and current therapies as well as current and prospective implantable DDDs, with a particular emphasis on local DDDs to combat bacterial osteomyelitis.

Fabrication of antibiotic-loaded dissolvable calcium sulfate beads: an in vitro mixing lab utilizing various antibiotic mixing formulas

Chronic periprosthetic joint infection (PJI) is a devastating complication that requires an aggressive eradication protocol. Local antimicrobial delivery via dissolvable calcium sulfate (CaSO4) using small-sized beads (3–8 mm) has been utilized as an adjunctive treatment combined with implant exchange, radical debridement, and antimicrobial loaded acrylic spacers. The non-exothermic setting of CaSO4 theoretically allows for any antimicrobial agent to be used, so long as mixing methods provide a consistent fabrication within a reasonable set time. This study performed the first in vitro mixing study, in which various antimicrobial agents, used singularly and in combination, were mixed with a synthetic CaSO4 product to observe and document their interactions. The study was performed in a simulated operating room environment. We report a standard mix formula with set times, testing 22 different antimicrobial agents, combinations, and doses. For some antimicrobials and combinations, set times using the standard formula were either too fast or exceedingly slow. For these 14 antimicrobial agents and combinations, we were able to arrive at individualized mixing methods. We present all mixing formulas and set times. In all, we were able to establish mixing methods that incorporate all antimicrobial agents and combinations that we have seen utilized via surgeon-directed use.

The Risk of Iatrogenic Hypercalcemia in Patients Undergoing Calcium Sulphate Beads Implantation in Prosthetic Joint Surgery: A Systematic Review

Calcium sulphate beads are increasingly being used in the management of prosthetic joint infections (PJI). Traditionally their use was limited to a void or dead space-filling combined with other additives such as Hydroxyapatite. Over the last decade, they have been developed to act more frequently as an antibiotics delivery system. Stimulan, a bio-absorbable form of Calcium sulfate, theoretically has an increased risk of hypercalcemia. Over the last few years, there have been published case reports which report it as an isolated cause of iatrogenic hypercalcemia. The sparsity of literature on this topic makes it difficult for surgeons to decide on the use of Calcium sulphate beads in patients with hypercalcemia predisposition in conditions like autoimmune disorders, sarcoidosis, malignancy, granulomatous diseases, heterotopic ossification, and hyperparathyroidism. The study was performed to assess the risk of hypercalcemia in patients after Calcium sulphate beads implantation in PJI. Two reviewers searched relevant literature in 3 online databases using cochrane methodology for systematic reviews. Studies reporting complications with the use of calcium sulphate beads in prosthetic joints were included. Studies reporting on less than five patients and studies reporting use in any other surgeries were excluded. The search of databases resulted in a total of 96 articles. After screening, a total of four articles were deemed suitable to be included in the analysis. A total of 1049 patients underwent calcium sulfate beads implantation, out of which 44 (4.2%) reported hypercalcemia with 41 (3.91%) transient in nature and 3 (0.28%) required management, including one with ICU admission. The result of this systematic review shows that calcium sulphate beads are safe and effective against PJI. There is a significant risk of transient hypercalcemia in susceptible patients and a low risk of symptomatic hypercalcemia.

Cytotoxicity and cell response of preosteoblast in calcium sulfate-augmented PMMA bone cement

Poly(methyl methacrylate) (PMMA) has been widely used in orthopedic applications, but bone ingrowth and toxic monomer release are drawback of this material. Particle reinforcement with osteoconductive substitute, such as calcium sulfate (CaSO₄), is one of the solutions used to modify PMMA bone cement. The current study investigated the mechanical, chemical and biological properties of CaSO₄-augmented bone cement. Mechanical strength was measured by a material testing machine. The concentration of methyl methacrylate (MMA) monomer from the various formulations of PMMA mixed with CaSO₄was measured by ultra-performance liquid chromatography (UPLC). CCK-8 assay and ALP assay were performed to evaluate cytotoxicity of released MMA monomer and cell differentiation. The attachment of cells to CaSO₄-augmented bone cement discs was observed by confocal and scanning electron microscopy, and surface topography was also evaluated by atomic force microscopy. The results revealed that increased CaSO₄weight ratios led to compromised mechanical strength and increased MMA monomer release. Cell density and cell differentiation on CaSO₄-augmented bone cement discs were decreased at CaSO₄weight ratios above 10%. In addition, the presence of micropores on the surface and surface roughness were both increased for PMMA composite discs containing higher levels of CaSO₄. These results demonstrated that fewer MC3T3-E1 cells on the surface of CaSO₄-PMMA composites was correlated to increased MMA monomer release, micropore number and surface roughness. In summary, the augmentation of a higher proportion of CaSO₄(>10 wt. %) to PMMA did not promote the biological properties of traditional PMMA bone cement.

Effectiveness and Safety of Biodegradable Calcium Sulfate Antibiotic Beads as Adjuvant Therapy in Vascular Graft Infections

This is a retrospective cohort study evaluating the safety and effectiveness of biodegradable calcium sulfate antibiotic beads in vascular graft infections compared with standard of care. No differences in acute kidney injury or hypercalcemia were observed between the cohorts. Recurrence of infection did not occur in the 13-patient bead cohort compared with 14 patients who had recurrence in the 45-patient nonbead cohort with a number needed to treat of 4.0.

The evolution from the two stage to the one stage procedure for biofilm based periprosthetic joint infections (PJI)

A definitive consensus on the optimal limb salvage protocol for infected total joints does not currently exist. Popular, is the two-stage revision which calls for the use of an antibiotic loaded spacer followed by a delayed exchange. Our question is whether single-stage revisions for biofilm based infected arthroplasties results in comparable or possibly better patient outcomes as compared to those reported for two-stage revisions. We retrospectively reviewed 500 cases of one-stage revisions for periprosthetic joint infections (PJI) using dual setup with radical debridement, definitive reconstruction with antibiotic loaded cement and implantation of antibiotic calcium sulfate pellets between the years 2005-2017. The revisions included 351 total knees, 122 hips, 2 hip-femur-knees, 13 shoulders, 10 elbows, and 2 shoulder-humerus-elbows. The patient population had a mean follow-up of 60 months (range: 24 months-14 years) and mean patient age of 61 years old, consisting of 250 males and 250 females. Patient comorbidities were reviewed, classified using McPherson's staging for PJIs, and compared to the Cierny & Mader classification system. Successful treatment was defined as a joint without recurrence of infection, for a minimum of 2 years, and limb preservation. Based on our findings, one-stage revision of PJIs demonstrates at least as good an infection eradication rate as two-stage revision: 88% vs 85% respectively.

Prevention and Killing Efficacy of Carbapenem Resistant Enterobacteriaceae (CRE) and Vancomycin Resistant Enterococci (VRE) Biofilms by Antibiotic-Loaded Calcium Sulfate Beads

Carbapenem-resistant Enterobacteriaceae (CRE) and vancomycin-resistant Enterococci (VRE) have emerged as multidrug-resistant (MDR) pathogens associated with periprosthetic joint infections (PJI). In this study, we evaluated the efficacy of antibiotic-loaded calcium sulfate beads (ALCSB) in inhibiting bacterial growth, encouraging biofilm formation and killing preformed biofilms of CRE and VRE. Three strains of Klebsiella pneumoniae (KP) and a strain of Enterococcus faecalis (EF) were used. ALCSB of 4.8-mm diameter were loaded with vancomycin (V) and gentamicin (G), V and rifampicin (R), V and tobramycin (T) or R and meropenem (M), and placed onto tryptic soy agar (TSA), spread with one of the test strains and incubated for 24 h at 37 °C. Beads were transferred daily onto fresh TSA spread plates and the zone of inhibition (ZOI) was recorded until no inhibition was observed. ALCSB containing R + M or R + V produced the most extensive ZOI up to 5 weeks. Biofilm prevention efficacy was investigated by challenging ALCSB daily with 5 × 10⁵ CFU/mL bacterial cells and analyzing for biofilm formation at challenges 1, 2 and 3. In the biofilm killing experiments, ALCSB were added to pre-grown 3-day biofilms of KP and EF strains, which were then analyzed at days 1 and 3 post-exposure. The CFU counts and confocal images of the attached cells showed that ALCSB treatment reduced colonization and biofilm formation significantly (5–7 logs) with combinations of R + M or R + V, compared to unloaded beads. This study provides evidence that the local release of antibiotics from ALCSB may be useful in treating the biofilms of multidrug-resistant strains of CRE and VRE.