Pharmacokinetics of topical and intravenous cefazolin in patients with clean surgical wounds

Pharmacokinetics of Locally Applied Antibiotic Prophylaxis for Implant-Based Breast Reconstruction

Importance

Antibiotic irrigation of breast implants is widely used internationally, but no clinical study has investigated the pharmacokinetics of antibiotic prophylaxis in the breast implant pocket.

Objectives

To evaluate how long locally applied gentamicin, cefazolin, and vancomycin concentrations in the implant pocket remain above the minimum inhibitory concentration (MIC) for the most common bacterial infections and to measure systemic uptake.

Design, Setting, and Participants

This prospective cohort study was performed at the Department of Plastic Surgery and Burns Treatment, Rigshospitalet, Copenhagen, Denmark, between October 25, 2021, and September 22, 2022, among 40 patients undergoing implant-based breast reconstruction who were part of the ongoing BREAST-AB trial (Prophylactic Treatment of Breast Implants With a Solution of Gentamicin, Vancomycin and Cefazolin Antibiotics for Women Undergoing Breast Reconstructive Surgery: a Randomized Controlled Trial). Patients were randomized to receive locally applied gentamicin, cefazolin, and vancomycin or placebo. Samples were obtained from the surgical breast drain and blood up to 10 days postoperatively.

Exposures

The breast implant and the implant pocket were irrigated with 160 μg/mL of gentamicin, 2000 μg/mL of cefazolin, and 2000 μg/mL of vancomycin in a 200-mL saline solution.

Main Outcomes and Measures

The primary outcome was the duration of antibiotic concentrations above the MIC breakpoint for Staphylococcus aureus according to the Clinical and Laboratory Standards Institute: gentamicin, 4 μg/mL; cefazolin, 2 μg/mL; and vancomycin, 2 μg/mL. Secondary outcomes included the time above the MIC for Pseudomonas aeruginosa and other relevant bacteria, as well as systemic uptake.

Results

The study included 40 patients (median age, 44.6 years [IQR, 38.3-51.4 years]; median body mass index, 23.9 [IQR, 21.7-25.9]) with a median number of 3 drain samples (range, 1-10 drain samples) and 2 blood samples (range, 0-6 blood samples). Vancomycin and cefazolin remained above the MIC for S aureus significantly longer than gentamicin (gentamicin, 0.9 days [95% CI, 0.5-1.2 days] for blood samples vs 6.9 days [95% CI, 2.9 to 10.9 days] for vancomycin [P = .02] vs 3.7 days [95% CI, 2.2-5.2 days] for cefazolin [P = .002]). The gentamicin level remained above the MIC for P aeruginosa for 1.3 days (95% CI, 1.0-1.5 days). Only cefazolin was detectable in blood samples, albeit in very low concentrations (median concentration, 0.04 μg/mL [range, 0.007-0.1 μg/mL]).

Conclusions and Relevance

This study suggests that patients treated with triple-antibiotic implant irrigation during breast reconstruction receive adequate prophylaxis for S aureus and other common implant-associated, gram-positive bacteria. However, the protection against P aeruginosa may be inadequate.

Prophylactic treatment of breast implants with a solution of gentamicin, vancomycin and cefazolin antibiotics for women undergoing breast reconstructive surgery: protocol for a randomised, double-blind, placebo-controlled trial (The BREAST-AB trial)

INTRODUCTION

Periprosthetic infection is one of the most severe complications following implant-based breast reconstruction affecting 5%-10% of the women. Currently, many surgeons apply antibiotics locally on the breast implant to reduce the risk of postoperative infection, but no randomised, placebo-controlled trials have tested the treatment's efficacy.

METHODS AND ANALYSIS

The BREAST-AB trial (BREAST-AntiBiotics) is an investigator-initiated, multicentre, randomised, placebo-controlled, double-blind trial of local treatment with gentamicin, vancomycin and cefazolin on breast implants in women undergoing implant-based breast reconstruction. The trial drug consists of 80 mg gentamicin, 1 g vancomycin and 1 g cefazolin dissolved in 500 mL of isotonic saline. The placebo solution consists of 500 mL isotonic saline. The trial drug is used to wash the dissected tissue pocket and the breast implant prior to insertion. The primary outcome is all-cause explantation of the breast implant within 180 days after the breast reconstruction surgery. This excludes cases where the implant is replaced with a new permanent implant, for example, for cosmetic reasons. Key long-term outcomes include capsular contracture and quality of life. The trial started on 26 January 2021 and is currently recruiting.

ETHICS AND DISSEMINATION

The trial was approved by the Regional Ethics Committee of the Capital Region (H-20056592) on 1 January 2021 and the Danish Medicines Agency (2020070016) on 2 August 2020. The main paper will include the primary and secondary outcomes and will be submitted to an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04731025.

Hematology and Culture Assessment of Cranially Implanted Rhesus Macaques (Macaca mulatta)

The use of percutaneous cranial implants in rhesus macaques (Macaca mulatta) has long been a valuable tool for neuroscience research. However, when treating and assessing these animals, veterinarians are required to make assumptions about diagnostic results due to a lack of research into how these implants affect physiology. Microbial cultures of cranial implant sites show an abundance of colonizing bacteria, but whether these microbes affect animal health and wellbeing is poorly understood. In addition, microbial antibiotic resistance can present significant health concerns for both the animals and the researchers. To help elucidate the relationship between percutaneous cranial implants and blood parameters, complete blood cell counts and serum chemistry results were assessed on 57 nonhuman primates at our institution from September 2001 to March 2017. Generalized estimating equations were used to compare the results before and after an animal's first implant surgery. This modelling showed that cranial implants were a significant predictor of alterations in the number of neutrophils, lymphocytes, and red blood cells, and in the concentration of hemoglobin, alkaline phosphatase, creatinine, calcium, phos- phorus, total protein, albumin, and globulin. Anaerobic and aerobic bacterial cultures were performed to identify bacteria associated with cranial implants. Staphylococcus spp., Streptococcus spp., and Corynebacterium spp. comprised the majority of the aerobic bacterial isolates, while Fusobacterium spp., Peptostreptococcus spp. and Bacterioides fragilis comprised the majority of anaerobic bacterial isolates. Using a Pearson r correlation for statistical analysis, we assessed whether any of these bacterial isolates developed antibiotic resistances over time. Cefazolin, the most frequently used antibiotic in monkeys in this study, was the only antimicrobial out of 41 agents tested to which bacteria developed resistance over time. These results indicate that percutaneous implants are associated with a generalized inflammatory state, multiple bacterial species are present at the implant site, and these bacteria may contribute to the inflammatory response.

Use of Intrawound Antibiotics in Orthopaedic Surgery

Intrawound antibiotics have been used in orthopaedic surgery procedures to prevent the development of surgical site infections. Local delivery of antibiotic powder has demonstrated a notable reduction in surgical site infection in rabbit and rodent in vivo models, as well as in other surgical fields, including vascular, colorectal, cardiothoracic, and dermatologic surgery. Intrawound antibiotic powder has been used in many orthopaedic applications, including spine surgery, total joint arthroplasty, trauma, foot and ankle reconstruction, and elbow surgery. Although the theory behind the use of intrawound antibiotic powder is promising, it has potential adverse effects, including antibiotic resistance, circulatory collapse, and decreased bone healing. In addition, most studies in the orthopaedic literature on the use of intrawound antibiotic powder are retrospective in nature.

Examining the Role of Antimicrobial Irrigation and Capsular Contracture: A Systematic Review and Meta-analysis

PURPOSE

The purpose of this study was to conduct a meta-analysis to determine if irrigation of breast implant pockets with antibiotics reduces the rate of capsular contracture (CC). Capsular contracture is the most common complication after primary augmentation mammoplasty, yet its etiology remains cryptogenic.

METHODS

PubMed was searched for publications from January 1 of 2000 through October of 2015. Studies with the following criteria were included: primary breast augmentation with implants, use of antimicrobial irrigation (AMI), and documentation of CC. The primary outcome studied was incidence of CC. The quality of included studies was assessed independently. Studies were meta-analyzed to obtain a pooled odds ratio (OR) describing the effect of AMI on CC.

RESULTS

The meta-analysis included 8 studies and 10,923 patients. A total of 5348 patients received AMI, and 5575 patients did not. Our analysis revealed that the combined AMI, the antibiotic irrigation subgroup, and the iodine subgroup were associated with an increased propensity for CC [OR, 2.60; 95% confidence interval (CI), 2.3-2.94, I = 97%, P < 0.00001; OR, 1.42; 95% CI, 1.14-1.78, I = 89%, P < 0.00001; OR, 0.54; 95% CI, 0.24-1.22, P = 0.05; I = 73], respectively.

CONCLUSIONS

Antimicrobial irrigation of implant pockets fails to reduce the propensity for CC. The authors recommend that further prospective multicenter trials be conducted to further elucidate the role of antibiotic irrigation in CC.

Surgical Site Irrigation in Plastic Surgery

BACKGROUND

The incidence of infection following breast implant reconstruction remains high at the level of 24%. Surgical site irrigation is commonly used for its prevention. However, the lack of evidence-based guidelines for antibiotic prophylaxis in breast implant surgery necessitates research for optimal irrigation technique.

OBJECTIVES

composition and exposure time of irrigation solution for surgical site infection (SSI) prophylaxis using an in vitro model of a surgical site.

METHODS

The study design was an in vitro model to assess antibiotic irrigation of a surgical site. Strains of Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Group A Streptococcus, and Pseudomonas aeruginosa were seeded on blood agar growth medium and irrigated with various antibiotic and antiseptic solutions under different exposure times. The presence and quantity of the colonies grown were estimated after 24-hour incubation. Repetition of the studies for 5 times with each investigated irrigation solution and microorganism was performed. Optimal irrigation agents were chosen based on the ability to achieve sterility with minimal tissue toxicity.

RESULTS

The optimal wound irrigation agents for SSI prophylaxis in our study were found to be 0.05% chlorhexidine or triple antibiotic antibiotic solutions. Adding of vancomycin to the irrigation solutions did not show an increase in their effectiveness. Prolonged irrigation exposure time was necessary to achieve sterility of the in vitro model of a surgical site.

CONCLUSIONS

We recommend 0.05% chlorhexidine or triple antibiotic solution for topical SSI prophylaxis in breast implant surgery. Sufficient time of irrigation can be achieved by maintaining some of the solution in the pocket and delaying drainage for at least 30 minutes.

LEVEL OF EVIDENCE 5

Intracavity lavage and wound irrigation for prevention of surgical site infection

BACKGROUND

Surgical site infections (SSIs) are wound infections that occur after an operative procedure. A preventable complication, they are costly and associated with poorer patient outcomes, increased mortality, morbidity and reoperation rates. Surgical wound irrigation is an intraoperative technique, which may reduce the rate of SSIs through removal of dead or damaged tissue, metabolic waste, and wound exudate. Irrigation can be undertaken prior to wound closure or postoperatively. Intracavity lavage is a similar technique used in operations that expose a bodily cavity; such as procedures on the abdominal cavity and during joint replacement surgery.

OBJECTIVES

To assess the effects of wound irrigation and intracavity lavage on the prevention of surgical site infection (SSI).

SEARCH METHODS

In February 2017 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid Embase and EBSCO CINAHL Plus. We also searched three clinical trials registries and references of included studies and relevant systematic reviews. There were no restrictions on language, date of publication or study setting.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of participants undergoing surgical procedures in which the use of a particular type of intraoperative washout (irrigation or lavage) was the only systematic difference between groups, and in which wounds underwent primary closure. The primary outcomes were SSI and wound dehiscence. Secondary outcomes were mortality, use of systemic antibiotics, antibiotic resistance, adverse events, re-intervention, length of hospital stay, and readmissions.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion at each stage. Two review authors also undertook data extraction, assessment of risk of bias and GRADE assessment. We calculated risk ratios or differences in means with 95% confidence intervals where possible.

MAIN RESULTS

We included 59 RCTs with 14,738 participants. Studies assessed comparisons between irrigation and no irrigation, between antibacterial and non-antibacterial irrigation, between different antibiotics, different antiseptics or different non-antibacterial agents, or between different methods of irrigation delivery. No studies compared antiseptic with antibiotic irrigation. Surgical site infectionIrrigation compared with no irrigation (20 studies; 7192 participants): there is no clear difference in risk of SSI between irrigation and no irrigation (RR 0.87, 95% CI 0.68 to 1.11; I2 = 28%; 14 studies, 6106 participants). This would represent an absolute difference of 13 fewer SSIs per 1000 people treated with irrigation compared with no irrigation; the 95% CI spanned from 31 fewer to 10 more SSIs. This was low-certainty evidence downgraded for risk of bias and imprecision.Antibacterial irrigation compared with non-antibacterial irrigation (36 studies, 6163 participants): there may be a lower incidence of SSI in participants treated with antibacterial irrigation compared with non-antibacterial irrigation (RR 0.57, 95% CI 0.44 to 0.75; I2 = 53%; 30 studies, 5141 participants). This would represent an absolute difference of 60 fewer SSIs per 1000 people treated with antibacterial irrigation than with non-antibacterial (95% CI 35 fewer to 78 fewer). This was low-certainty evidence downgraded for risk of bias and suspected publication bias.Comparison of irrigation of two agents of the same class (10 studies; 2118 participants): there may be a higher incidence of SSI in participants treated with povidone iodine compared with superoxidised water (Dermacyn) (RR 2.80, 95% CI 1.05 to 7.47; low-certainty evidence from one study, 190 participants). This would represent an absolute difference of 95 more SSIs per 1000 people treated with povidone iodine than with superoxidised water (95% CI 3 more to 341 more). All other comparisons found low- or very low-certainty evidence of no clear difference between groups.Comparison of two irrigation techniques: two studies compared standard (non-pulsed) methods with pulsatile methods. There may, on average, be fewer SSIs in participants treated with pulsatile methods compared with standard methods (RR 0.34, 95% CI 0.19 to 0.62; I2 = 0%; two studies, 484 participants). This would represent an absolute difference of 109 fewer SSIs occurring per 1000 with pulsatile irrigation compared with standard (95% CI 62 fewer to 134 fewer). This was low-certainty evidence downgraded twice for risks of bias across multiple domains. Wound dehiscenceFew studies reported wound dehiscence. No comparison had evidence for a difference between intervention groups. This included comparisons between irrigation and no irrigation (one study, low-certainty evidence); antibacterial and non-antibacterial irrigation (three studies, very low-certainty evidence) and pulsatile and standard irrigation (one study, low-certainty evidence). Secondary outcomesFew studies reported outcomes such as use of systemic antibiotics and antibiotic resistance and they were poorly and incompletely reported. There was limited reporting of mortality; this may have been partially due to failure to specify zero events in participants at low risk of death. Adverse event reporting was variable and often limited to individual event types. The evidence for the impact of interventions on length of hospital stay was low or moderate certainty; where differences were seen they were too small to be clinically important.

AUTHORS' CONCLUSIONS

The evidence base for intracavity lavage and wound irrigation is generally of low certainty. Therefore where we identified a possible difference in the incidence of SSI (in comparisons of antibacterial and non-antibacterial interventions, and pulsatile versus standard methods) these should be considered in the context of uncertainty, particularly given the possibility of publication bias for the comparison of antibacterial and non-antibacterial interventions. Clinicians should also consider whether the evidence is relevant to the surgical populations under consideration, the varying reporting of other prophylactic antibiotics, and concerns about antibiotic resistance.We did not identify any trials that compared an antibiotic with an antiseptic. This gap in the direct evidence base may merit further investigation, potentially using network meta-analysis; to inform the direction of new primary research. Any new trial should be adequately powered to detect a difference in SSIs in eligible participants, should use robust research methodology to reduce the risks of bias and internationally recognised criteria for diagnosis of SSI, and should have adequate duration and follow-up.

Local Intra-wound Administration of Powdered Antibiotics in Orthopaedic Surgery

Surgical site infection (SSI) is one of the most common complications after orthopaedic surgery, leading to significant morbidity and its associated costs. Surgical guidelines strongly recommend the use of systemic antibiotic prophylaxis to reduce the risk for developing SSI. Locally administered powdered antibiotics have the potential to provide remarkably high intra-wound concentrations without risk for systemic toxicity. However, a paucity of high quality evidence in the orthopaedic literature has prevented widespread adoption of this technique. The majority of clinical studies on local intra-wound antibiotics have evaluated the use of topical powdered vancomycin in spinal surgery, though only a single prospective study currently exists. This review will discuss all the available evidence describing the effectiveness, pharmacokinetics, and potential adverse effects with the use of topical powdered antibiotics in orthopedic surgery.

Antibiotic prophylaxis in reduction mammaplasty: study protocol for a randomized controlled trial

Background

The role of antibiotics in surgical procedures where the risk of surgical site infection (SSI) is low remains uncertain. There is, to date, no evidence to justify the routine use of antibiotics in postoperative reduction mammaplasty. The aim of this study is to evaluate the effect of postoperative antibiotic treatment on the occurrence of SSI after breast reduction surgery.

Methods

This is a double-blind randomized clinical trial with 124 breast hypertrophy patients allocated to two treatment groups: antibiotic (n = 62) and placebo (n = 62). All patients will undergo reduction mammoplasty, performed by the same surgical team. The surgeons will raise the nipple-areola complex by the superomedial pedicle technique. The patients will receive antibiotics intravenously during anesthetic induction and every 6 hours thereafter during their 24-hour hospital stay. During discharge from the hospital, each patient will receive a numbered package containing either cephalexin or placebo capsules and will be directed to take one capsule every 6 hours for 7 days. Neither the surgery team nor the patients will know the contents of the capsules. Patients will be monitored for the occurrence of SSI once weekly during the first 30 days following hospital discharge by a single surgeon who is blinded to their treatment group. SSI will be evaluated based on the definition adopted by the Centers for Disease Control and Prevention.

Discussion

Due to the variety of risk factors for SSI and limited case studies, conclusions regarding the effect of antibiotics on the occurrence of SSIs following reduction mammaplasty are potentially biased. In recent studies, perioperative antibiotic prophylaxis was effective in preventing infection and is therefore recommended in clinical practice. However, antibiotic use in the postoperative period still remains controversial.

Trial registration

Clinicaltrials.gov Identifier: NCT02569866. Registered on 4 October 2015.

Feasibility of Subcutaneous Gentamicin and Pressurized Irrigation as Adjuvant Strategies to Reduce Surgical Site Infection in Colorectal Surgery: Results of a Pilot Study

Surgical site infections (SSIs) remain a common and costly morbidity after colorectal surgery. This rate remains high even in the setting of strict adherence to Surgical Care Improvement Project Protocols. The aim of our pilot study was to determine the feasibility and safety of subcutaneous gentamicin injection or pressurized irrigation as adjuncts to reduce SSI. A total of 132 patients who underwent colorectal surgery at the VA North Texas Health Care System were prospectively assigned to a pressurized irrigation group (n = 44), a preincision gentamicin injection group (n = 48), or control (n = 40). The primary objective was to assess safety and feasibility of these strategies. Patient demographics were matched among groups. Univariate and multivariate analyses were performed to identify possible predictions of SSI in this cohort. The rate of SSI in the control group was 25 per cent, 13.5 per cent in the pressurized irrigation group, and 12.5 per cent in the gentamicin group ( P = 0.26). Combined, the intervention groups had a 13 per cent SSI versus 25 per cent control ( P = 0.09). Operative time was not increased by the interventions and no intraoperative complications specifically related to the interventions were noted. Postoperative complications were not different between groups. Both albumin and body mass index were associated with SSI. Body mass index was and independent predictor of SSI ( P = 0.006). In conclusion, this pilot study demonstrates the feasibility of the interventions described. There was no detrimental effect of either intervention. There was trend toward a reduction in SSI in the intervention group, which warrants further investigation.

Intra-operative wound irrigation to reduce surgical site infections after abdominal surgery: a systematic review and meta-analysis

PURPOSE

Surgical site infection (SSI) remains to be one of the most frequent infectious complications following abdominal surgery. Prophylactic intra-operative wound irrigation (IOWI) before skin closure has been proposed to reduce bacterial wound contamination and the risk of SSI. However, current recommendations on its use are conflicting especially concerning antibiotic and antiseptic solutions because of their potential tissue toxicity and enhancement of bacterial drug resistances.

METHODS

To analyze the existing evidence for the effect of IOWI with topical antibiotics, povidone-iodine (PVP-I) solutions or saline on the incidence of SSI following open abdominal surgery, a systematic review and meta-analysis of randomized controlled trials (RCTs) was carried out according to the recommendations of the Cochrane Collaboration.

RESULTS

Forty-one RCTs reporting primary data of over 9000 patients were analyzed. Meta-analysis on the effect of IOWI with any solution compared to no irrigation revealed a significant benefit in the reduction of SSI rates (OR = 0.54, 95 % confidence Interval (CI) [0.42; 0.69], p < 0.0001). Subgroup analyses showed that this effect was strongest in colorectal surgery and that IOWI with antibiotic solutions had a stronger effect than irrigation with PVP-I or saline. However, all of the included trials were at considerable risk of bias according to the quality assessment.

CONCLUSION

These results suggest that IOWI before skin closure represents a pragmatic and economical approach to reduce postoperative SSI after abdominal surgery and that antibiotic solutions seem to be more effective than PVP-I solutions or simple saline, and it might be worth to re-evaluate their use for specific indications.

Colistin-loaded silk membranes against wound infection with Pseudomonas aeruginosa

BACKGROUND

Wound infections caused by multidrug-resistant bacteria are a major issue in wound care. An occlusive dressing delivering an antimicrobial agent to the wound may be advantageous. The objective of this study was to evaluate an occlusive silk membrane loaded with colistin to establish an effective antimicrobial wound dressing against Gram-negative bacteria in vitro and in vivo.

METHODS

ST-silk protein membranes (thickness, 100 μm; pore size, <100 nm) were loaded with log-scale colistin dilutions (0.027 to 270 mg/ml) and tested in a modified microbroth dilution assay against Pseudomonas aeruginosa (American Type Culture Collection 27853). A rat burn infection model was used to demonstrate the antimicrobial activity of ST-silk membranes loaded with 270 mg/ml colistin. Finally, a porcine wound infection model was used to study dose response (2.7, 27, and 270 mg/ml colistin loading concentration) in a time-dependent manner (0, 2, 4, and 6 days).

RESULTS

The in vitro study demonstrated a concentration-dependent antimicrobial effect against P. aeruginosa, with complete elimination at the highest loading concentrations (2.7, 27, and 270 mg/ml). All colistin membranes demonstrated lower colony-forming unit counts compared with the corresponding phosphate-buffered saline or carrier controls. The rat burn infection model demonstrated a colony-forming unit reduction of greater than 3 log-scales for the colistin-loaded ST-silk membranes after 3 days. On average, the wounds' colony-forming unit quantity remained at greater than 1000 during the entire follow-up of 6 days, apart from three wounds where complete bacterial clearance was observed.

CONCLUSION

This study demonstrates that occlusive ST-silk membranes loaded with an antimicrobial agent may be an effective dressing for infected wounds.