Local concentrations of gentamicin obtained by microdialysis after a controlled application of a GentaColl sponge in a porcine model

Dynamic Assessment of Local Abdominal Tissue Concentrations of Cisplatin During a HIPEC Procedure: Insights from a Porcine Model

BACKGROUND

This study aimed to establish a feasible large porcine model for dynamic assessment of cisplatin concentrations in carcinomatosis-relevant abdominal tissues using microdialysis during and after HIPEC combined with cytoreductive surgery.

METHODS

In total, eight pigs underwent open abdominal cytoreductive surgery followed by HIPEC. Microdialysis was employed for dynamic cisplatin concentration sampling in abdominal organs and tissue. Cisplatin dialysate concentrations were analyzed using the UPLC-MS/MS method. STATA (version 18.0) was used to perform a two-compartment model with a zero-order distribution to analyze pharmacokinetic parameters.

RESULTS

Detectable cisplatin concentrations in the evaluated target tissues persisted for at least 6 h post-HIPEC. Higher concentrations were found in superficial tissues; however, the difference was not statistically significant. The cisplatin concentrations were comparable for the stomach, rectum, and liver but higher in the peritoneal lining of the abdominal wall, with the lowest median average peak concentration (Cmax) in the rectum (0.50 µg/mL) and the highest median Cmax in the peritoneum (2.80 µg/mL). No statistically significant differences in cisplatin area under the curve from time zero to the time of the last sample collection (AUC0-last) were found between any of the abdominal compartments except the peritoneal lining of the abdominal wall, which was significantly higher compared with most of the other abdominal tissues {smallest difference; peritoneum 1/liver 2; 1.96 [95% confidence interval (CI) 0.90; 4.26, P = 0.09] and largest difference; peritoneum 3/rectum profound; 4.60 [95% CI 1.94; 10.90, P = 0.001]}.

CONCLUSIONS

Our investigation revealed comparable cisplatin concentrations across abdominal organ surfaces, except higher concentrations in the peritoneal lining of the abdominal wall than in the stomach, rectum, and liver. This model holds promise for future research into HIPEC interventions and anticancer effectiveness.

Eradication of Staphylococcus aureus in Implant-Associated Osteomyelitis by an Injectable In Situ-Forming Depot Antibiotics Delivery System

BACKGROUND

Bone infections with Staphylococcus aureus are notoriously difficult to treat and have high recurrence rates. Local antibiotic delivery systems hold the potential to achieve high in situ antibiotic concentrations, which are otherwise challenging to achieve via systemic administration. Existing solutions have been shown to confer suboptimal drug release and distribution. Here we present and evaluate an injectable in situ-forming depot system termed CarboCell. The CarboCell technology provides sustained and tuneable release of local high-dose antibiotics.

METHODS

CarboCell formulations of levofloxacin or clindamycin with or without antimicrobial adjuvants cis-2-decenoic acid or cis-11-methyl-2-dodecenoic acid were tested in experimental rodent and porcine implant-associated osteomyelitis models. In the porcine models, debridement and treatment with CarboCell-formulated antibiotics was carried out without systemic antibiotic administration. The bacterial burden was determined by quantitative bacteriology.

RESULTS

CarboCell formulations eliminated S. aureus in infected implant rat models. In the translational implant-associated pig model, surgical debridement and injection of clindamycin-releasing CarboCell formulations resulted in pathogen-free bone tissues and implants in 9 of 12 and full eradication in 5 of 12 pigs.

CONCLUSIONS

Sustained release of antimicrobial agents mediated by the CarboCell technology demonstrated promising therapeutic efficacy in challenging translational models and may be beneficial in combination with the current standard of care.

Regional antibiotic delivery for sternal wound infection prophylaxis a systematic review and meta-analysis of randomized controlled trials

Despite evidence suggesting the benefit of prophylactic regional antibiotic delivery (RAD) to sternal edges during cardiac surgery, it is seldom performed in clinical practice. The value of topical vancomycin and gentamicin for sternal wound infections (SWI) prophylaxis was further questioned by recent studies including randomized controlled trials (RCTs). The aim of this systematic review and meta-analysis was to comprehensively assess the safety and effectiveness of RAD to reduce the risk of SWI.We screened multiple databases for RCTs assessing the effectiveness of RAD (vancomycin, gentamicin) in SWI prophylaxis. Random effects meta-analysis was performed. The primary endpoint was any SWI; other wound complications were also analysed. Odds Ratios served as the primary statistical analyses. Trial sequential analysis (TSA) was performed.Thirteen RCTs (N = 7,719 patients) were included. The odds of any SWI were significantly reduced by over 50% with any RAD: OR (95%CIs): 0.49 (0.35-0.68); p < 0.001 and consistently reduced in vancomycin (0.34 [0.18-0.64]; p < 0.001) and gentamicin (0.58 [0.39-0.86]; p = 0.007) groups (psubgroup = 0.15). Similarly, RAD reduced the odds of SWI in diabetic and non-diabetic patients (0.46 [0.32-0.65]; p < 0.001 and 0.60 [0.44-0.83]; p = 0.002 respectively). Cumulative Z-curve passed the TSA-adjusted boundary for SWIs suggesting adequate power has been met and no further trials are needed. RAD significantly reduced deep (0.60 [0.43-0.83]; p = 0.003) and superficial SWIs (0.54 [0.32-0.91]; p = 0.02). No differences were seen in mediastinitis and mortality, however, limited number of studies assessed these endpoints. There was no evidence of systemic toxicity, sternal dehiscence and resistant strains emergence. Both vancomycin and gentamicin reduced the odds of cultures outside their respective serum concentrations' activity: vancomycin against gram-negative strains: 0.20 (0.01-4.18) and gentamicin against gram-positive strains: 0.42 (0.28-0.62); P < 0.001. Regional antibiotic delivery is safe and effectively reduces the risk of SWI in cardiac surgery patients.

Septic arthritis and osteomyelitis of the pubic symphysis – a retrospective study of 26 patients

Abstract. Introduction: Septic arthritis and osteomyelitis of the pubic symphysis (SAS) are rare conditions with nonspecific symptoms leading to diagnostic delay and treatment. Aim: We draw awareness to this condition elucidating the diagnostic procedures, surgical intervention and antibiotic management. Methods: This entail a retrospective follow-up study of 26 consecutive patients, median age of 71 years (range: 48–89) surgically treated for septic arthritis of the pubic symphysis between 2009 and 2020. Patient files, diagnostic imaging and bacterial cultures were evaluated. Results: Before diagnosed with SAS, 21 of the patients had previous pelvic surgery (16 due to malign conditions, 5 due to benign conditions), while 5 of the patients were not previously operated. Median follow-up period after SAS surgery was 18.5 months (range: 8 to 144.5 months). Dominating symptoms were severe suprapubic/pubic pain (n = 26), gait difficulties (n = 10) and intermittent fever (n = 9). Diagnostic delay was between 1 and 12 months. The diagnostic imaging included magnetic resonance imaging (MRI) (n = 24), computer tomography (CT) (n = 17) and/or PET-CT (n = 10), predominantly displaying bone destruction/erosion of the symphysis (n = 13), abscess (n = 12) and/or fistula (n = 5) in the adjacent muscles. All patients underwent surgical debridement with resection of the symphysis and received a minimum of 6 weeks antibiotic treatment. Fourteen patients presented with monocultures and 4 patients with polycultures. Five patients underwent at least one revision surgery. Twenty-three patients experienced postoperative pain relief at 6 weeks follow-up, and 19 patients were ambulant without walking aids. Conclusion: SAS are rare conditions and should be suspected in patients with infection, pubic pain and impaired gait, especially after pelvic surgery. Bone infection, abscess and fistula near the symphysis can be visualized with proper imaging, most frequently with MRI. For most patients in this cohort surgical debridement combined with a minimum of 6 weeks antibiotic treatment resulted in pain relief, improved walking ability and a low recurrence rate.

Moxifloxacin Concentrations in the Knee Joint, Tibial Bone, and Soft Tissue When Combined with Rifampicin: A Randomized Porcine Microdialysis Study

BACKGROUND

Peri and postoperative antibiotics are key adjuvant treatment tools in the management of periprosthetic joint infection (PJI). The aim of this study was to evaluate the effect of rifampicin on the area under the moxifloxacin concentration-time curve from 0 to 24 hours (AUC0-24) in the synovial fluid of the knee joint, tibial bone, and adjacent subcutaneous tissue under steady-state conditions using microdialysis in a porcine model.

METHODS

Twenty female pigs were randomized to receive oral treatment with moxifloxacin monotherapy (Group A, n = 10) of 400 mg once daily for 3 days or a combination therapy (Group B, n = 10) of 400 mg of moxifloxacin once daily for 3 days and 450 mg of rifampicin twice daily for 7 days. Microdialysis was used for sampling the synovial fluid of the knee joint, tibial cancellous and cortical bone, and adjacent subcutaneous tissues. Plasma samples were taken as a reference. Measurements were obtained for 24 hours.

RESULTS

Coadministration of moxifloxacin and rifampicin resulted in reductions of the moxifloxacin AUC0-24 in all targeted tissue compartments by 67% to 85% (p < 0.05). The corresponding change in plasma was 20% (p = 0.49). For both groups, the tissue penetration (the ratio of tissue free fraction AUC0-24 to plasma free fraction AUC0-24 [fAUCtissue/fAUCplasma]) was incomplete in all investigated compartments. The highest moxifloxacin tissue penetration was in the knee joint synovial fluid: 0.59 (Group A) and 0.24 (Group B). The lowest tissue penetration was in the cortical bone: 0.17 (Group A) and 0.03 (Group B).

CONCLUSIONS

We found a significant reduction of the moxifloxacin concentration, expressed as the AUC0-24, in tissues relevant to acute PJI treatment when coadministered with rifampicin.

CLINICAL RELEVANCE

The concentrations within the targeted tissue compartments were reduced significantly more than the concentrations in plasma, which may be particularly important as plasma concentrations are used in clinical practice to assess moxifloxacin treatment sufficiency.

Double-dose cefuroxime concentrations in bone, synovial fluid of the knee joint and subcutaneous adipose tissue-A randomised porcine microdialysis study

This study evaluated target tissue concentrations of double dose cefuroxime administered intravenously as either one 15 min infusion of 3000 mg (Group 1) or two single 15 min infusions of 1500 mg administered 4 h apart (Group 2). Sixteen pigs were randomised into two groups of eight. Cortical and cancellous bone, synovial fluid of the knee joint and subcutaneous adipose tissue concentrations were measured based on sampling via microdialysis. Plasma samples were collected as a reference. Comparison of the groups was based on time with concentrations above relevant minimal inhibitory concentrations (fT>MIC) of 4 μg/mL. The mean time fT>MIC (4 μg/mL) across compartments was longer for Group 2 (280-394 min) than for Group 1 (207-253 min) (p<0.01). Cortical bone showed a tendency towards longer fT>MIC (4 μg/mL) in Group 2 (280 min) than in Group 1 (207 min) (p = 0.053). Within 50 min after administration, the mean concentration of 4 μg/mL was reached in all compartments for both groups. The mean concentrations decreased below 4 μg/mL after approximately 4 h (Group 1) and 3 h (Group 2) from initiation of administration (time zero). During an 8 h interval, double-dose cefuroxime administered as 2 × 1500 mg with a 4 h interval provides longer time above MIC breakpoint for Staphylococcus aureus (4 μg/mL) than a single bolus of 3000 mg cefuroxime. To maintain sufficient tissue concentrations during longer surgeries, re-administration of cefuroxime (1500 mg) should be considered 3 h after the first administration.

Vancomycin bone and tissue concentrations following tibial intraosseous administration - evaluated in a porcine model

Introduction. Systemic perioperative vancomycin may not provide sufficient prophylactic target-site concentrations in the prevention of prosthetic joint infections. Intraosseous vancomycin potentially provides high target-site concentrations. The objective of the present study was to evaluate the local bone and tissue concentrations following tibial intraosseous vancomycin administration in a porcine model. Methods. Eight pigs received 500 mg diluted vancomycin (50 mg/mL) through an intraosseous cannula into the proximal tibial cancellous bone. No tourniquet was applied. Microdialysis was applied for sampling of vancomycin concentrations in adjacent tibial cancellous bone, in cortical bone, in the intramedullary canal of the diaphysis, in the synovial fluid of the knee joint, and in the subcutaneous tissue. Plasma samples were obtained as a systemic reference. Samples were collected for 12 h. Results. High vancomycin concentrations were found in the tibial cancellous bone with a mean peak drug concentration of 1236 (range 28-5295)  µ g / mL , which remained high throughout the sampling period. The mean (standard deviation) peak drug concentration in plasma was 19 (2)  µ g / mL , which was obtained immediately after administration. Peak drug concentration, time to peak drug concentration, and area under the concentration-time curve were within the same range in the intramedullary canal, the synovial fluid of the knee, and the subcutaneous tissue. Conclusion. Tibial intraosseous administration of vancomycin provided high concentrations in tibial cancellous bone throughout a 12 h period but with an unpredictable and wide range of peak concentration. The systemic absorption was high and immediate, thus mirroring an intravenous administration. Low mean concentrations were found in all the remaining compartments.

Pathological and microbiological impact of a gentamicin-loaded biocomposite following limited or extensive debridement in a porcine model of osteomyelitis

Aims

CERAMENT|G is an absorbable gentamicin-loaded biocomposite used as an on-site vehicle of antimicrobials for the treatment of chronic osteomyelitis. The purpose of the present study was to investigate the sole effect of CERAMENT|G, i.e. without additional systemic antimicrobial therapy, in relation to a limited or extensive debridement of osteomyelitis lesions in a porcine model.

Methods

Osteomyelitis was induced in nine pigs by inoculation of 10⁴ colony-forming units (CFUs) of Staphylococcus aureus into a drill hole in the right tibia. After one week, the pigs were allocated into three groups. Group A (n = 3) received no treatment during the study period (19 days). Groups B (n = 3) and C (n = 3) received limited or extensive debridement seven days postinoculation, respectively, followed by injection of CERAMENT|G into the bone voids. The pigs were euthanized ten (Group C) and 12 (Group B) days after the intervention.

Results

All animals presented confirmatory signs of bone infection post-mortem. The estimated amount of inflammation was substantially greater in Groups A and B compared to Group C. In both Groups B and C, peptide nucleic acid fluorescence in situ hybridization (PNA FISH) of CERAMENT|G and surrounding bone tissue revealed bacteria embedded in an opaque matrix, i.e. within biofilm. In addition, in Group C, the maximal measured post-mortem gentamicin concentrations in CERAMENT|G and surrounding bone tissue samples were 16.6 μg/ml and 6.2 μg/ml, respectively.

Conclusion

The present study demonstrates that CERAMENT|G cannot be used as a standalone alternative to extensive debridement or be used without the addition of systemic antimicrobials.

Cite this article: Bone Joint Res 2020;9(7):394–401.