The Detection of Bacteria and Matrix Proteins on Clinically Benign and Pathologic Implants

Photodynamic Therapy Minimally Affects HEMA-DMAEMA Hydrogel Viscoelasticity

Soft matter implants are a rapidly growing field in medicine for reconstructive surgery, aesthetic treatments, and regenerative medicine. Though these procedures are efficacious, all implants carry risks associated with microbial infection which are often aggressive. Preventative and responsive measures exist but are limited in applicability to soft materials. Photodynamic therapy (PDT) presents a means to perform safe and effective antimicrobial treatments in proximity to soft implants. HEMA-DMAEMA hydrogels are prepared with the photosensitizer methylene blue included at 10 and 100 µM in solution used for swelling over 2 or 4 days. Thirty minutes or 5 h of LED illumination at9.20 m W c m 2 $9.20\frac{{mW}}{{c{m}^2}}$ is then used for PDT-induced generation of reactive oxygen species in direct contact with hydrogels to test viable limits of treatment. Frequency sweep rheological measurements reveal minimal overall changes in terms of loss modulus and loss factor but a statistically significant drop in storage modulus for some PDT doses, though within the range of controls and biological variation. These mild impacts suggest the feasibility of PDT application for infection clearing in proximity to soft implants. Future investigation with additional hydrogel varieties and current implant models will further detail the safety of PDT in implant applications.

Management of Biofilm with Breast Implant Surgery

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand how bacteria negatively impact aesthetic and reconstructive breast implants. 2. Understand how bacteria infect breast implants. 3. Understand the evidence associated with common implant infection-prevention strategies, and their limitations. 4. Understand why implementation of bacteria-mitigation strategies such as antibiotic administration or "no-touch" techniques may not indefinitely prevent breast implant infection.

SUMMARY

Bacterial infection of aesthetic and reconstructive breast implants is a common and expensive problem. Subacute infections or chronic capsular contractures leading to device explantation are the most commonly documented sequelae. Although bench and translational research underscores the complexities of implant-associated infection, high-quality studies with adequate power, control groups, and duration of follow-up are lacking. Common strategies to minimize infections use antibiotics-administered systemically, in the breast implant pocket, or by directly bathing the implant before insertion-to limit bacterial contamination. Limiting contact between the implant and skin or breast parenchyma represents an additional common strategy. The clinical prevention of breast implant infection is challenged by the clean-contaminated nature of breast parenchyma, and the variable behavior of not only specific bacterial species but also their strains. These factors impact bacterial virulence and antibiotic resistance.

Implant-based breast surgery and capsular formation: when, how and why?-a narrative review

Background and Objective

Implant-based breast surgery is a common procedure for both reconstructive and aesthetic purposes. Breast implants, like any foreign object, trigger the formation of a capsule around them. While generally harmless, the capsule can undergo fibrotic changes leading to capsular contracture, which can negatively impact surgical outcomes and patient well-being. Additionally, rare but serious complications, such as breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) and capsule-associated squamous cell carcinoma, have been reported. This paper aims to review the physiology of capsular formation, identify factors contributing to capsule-related pathologies, and discuss their clinical implications.

Methods

A review of relevant literature was conducted by searching databases for articles published between inception and September 2022. The search included but not limited to terms such as "capsular formation" and "capsular contracture". Selected articles were critically analyzed to address the objectives of this review.

Key Content and Findings

Capsular formation involves interactions between the implant surface, surrounding tissues, and the immune system. Factors influencing pathological changes in the capsule include genetic predisposition, bacterial contamination, implant characteristics, and surgical techniques. Capsular contracture, characterized by tissue hardening, pain, and implant distortion, remains the most common complication. Rare but life-threatening conditions, such as BIA-ALCL and capsule-associated squamous cell carcinoma, necessitate vigilant monitoring and early detection.

Conclusions

Understanding the physiology of capsular formation and its associated pathologies is crucial for healthcare providers involved in implant-based breast surgery. Efforts should focus on minimizing the risk of capsular contracture through improved implant materials, surgical techniques, and infection prevention. The emergence of BIA-ALCL and capsule-associated squamous cell carcinoma underscores the importance of long-term surveillance and prompt diagnosis. Further research is needed to uncover underlying mechanisms and develop preventive measures and treatments for these complications. Enhancing our knowledge and clinical management of capsular formation will lead to safer and more successful outcomes in implant-based breast surgery.

A prospective randomized clinical trial to assess antibiotic pocket irrigation on tissue expander breast reconstruction

Bacterial infection is the most common complication following staged post-mastectomy breast reconstruction initiated with a tissue expander (TE). To limit bacterial infection, antibiotic irrigation of the surgical site is commonly performed despite little high-quality data to support this practice. We performed a prospective randomized control trial to compare the impact of saline irrigation alone to a triple antibiotic irrigation regimen (1 g cefazolin, 80 mg gentamicin, and 50,000 units of bacitracin in 500 mL of saline) for breast implant surgery. The microbiome in breasts with cancer (n = 16) was compared to those without (n = 16), as all patients (n = 16) had unilateral cancers but bilateral mastectomies (n = 32). Biologic and prosthetic specimens procured both at the time of mastectomy and during TE removal months later were analyzed for longitudinal comparison. Outcomes included clinical infection, bacterial abundance, and relative microbiome composition. No patient in either group suffered a reconstructive failure or developed an infection. Triple antibiotic irrigation administered at the time of immediate TE reconstruction did not reduce bacterial abundance or impact microbial diversity relative to saline irrigation at the time of planned exchange. Implanted prosthetic material adopted the microbial composition of the surrounding host tissue. In cancer-naïve breasts, relative to saline, antibiotic irrigation increased bacterial abundance on periprosthetic capsules (P = 0.03) and acellular dermal matrices (P = 0.04) and altered the microbiota on both. These data show that, relative to saline only, the use of triple antibiotic irrigation in TE breast reconstruction does impact the bacterial abundance and diversity of certain biomaterials from cancer-naïve breasts. IMPORTANCE The lifetime risk of breast cancer is ~13% in women and is treated with a mastectomy in ~50% of cases. The majority are reconstructed, usually starting with a tissue expander to help restore the volume for a subsequent permanent breast implant or the women's own tissues. The biopsychosocial benefits of breast reconstruction, though, can be tempered by a high complication rate of at least 7% but over 30% in some women. Bacterial infection is the most common complication, and can lead to treatment delays, patient physical and emotional distress and escalating health care cost. To limit this risk, plastic surgeons have tried a variety of strategies to limit bacterial infection including irrigating the pocket created after removing the breast implant with antibiotic solutions, but good-quality data are scarce. Herein, we study the value of antibiotics in pocket irrigation using a robust randomized clinical trial design and molecular microbiology approaches.

Prophylactic Antibiotics for Deep Inferior Epigastric Perforator Flap Breast Reconstruction: A Comparison between Three Different Duration Approaches

There is no consensus on the duration of prophylactic antibiotic use for autologous breast reconstruction after mastectomy. We attempted to standardize the use of prophylactic antibiotics after mastectomy using a deep inferior epigastric perforator flap for the breast reconstruction procedure.

Methods

This retrospective case series included 108 patients who underwent immediate breast reconstruction with a deep inferior epigastric perforator flap at the Ditmanson Medical Foundation Chia-Yi Christian Hospital between 2012 and 2019. Patients were divided into three groups based on the duration of prophylactic antibiotic administration (1, 3, and >7 days) for patients with drains. Data were analyzed between January and April 2021.

Results

The prevalence of surgical site infection in the breast was 0.93% (1/108), and in the abdomen it was 0%. The patient groups did not differ by age, body mass index, smoking status, or neoadjuvant chemotherapy. Only one patient experienced surgical site infection in the breast after half-deep necrosis of the inferior epigastric perforator flap. There were no significant differences in surgical site infection based on the duration of prophylactic antibiotic use. The operation time, methods of breast surgery, volume of fluid drainage in the first 3 days of the abdominal and breast drains, and day of removal of the abdominal and breast drains did not affect surgical site infection.

Conclusion

Based on these data, we do not recommend extending prophylactic antibiotics beyond 24 hours in deep inferior epigastric perforator reconstruction.

Staphylococcus aureus Breast Implant Infection Isolates Display Recalcitrance To Antibiotic Pocket Irrigants

Breast implant-associated infections (BIAIs) are the primary complication following placement of breast prostheses in breast cancer reconstruction. Given the prevalence of breast cancer, reconstructive failure due to infection results in significant patient distress and health care expenditures. Thus, effective BIAI prevention strategies are urgently needed. This study tests the efficacy of one infection prevention strategy: the use of a triple antibiotic pocket irrigant (TAPI) against Staphylococcus aureus, the most common cause of BIAIs. TAPI, which consists of 50,000 U bacitracin, 1 g cefazolin, and 80 mg gentamicin diluted in 500 mL of saline, is used to irrigate the breast implant pocket during surgery. We used in vitro and in vivo assays to test the efficacy of each antibiotic in TAPI, as well as TAPI at the concentration used during surgery. We found that planktonically grown S. aureus BIAI isolates displayed susceptibility to gentamicin, cefazolin, and TAPI. However, TAPI treatment enhanced biofilm formation of BIAI strains. Furthermore, we compared TAPI treatment of a S. aureus reference strain (JE2) to a BIAI isolate (117) in a mouse BIAI model. TAPI significantly reduced infection of JE2 at 1 and 7 days postinfection (dpi). In contrast, BIAI strain 117 displayed high bacterial burdens in tissues and implants, which persisted to 14 dpi despite TAPI treatment. Lastly, we demonstrated that TAPI was effective against Pseudomonas aeruginosa reference (PAO1) and BIAI strains in vitro and in vivo. Together, these data suggest that S. aureus BIAI strains employ unique mechanisms to resist antibiotic prophylaxis treatment and promote chronic infection. IMPORTANCE The incidence of breast implant associated infections (BIAIs) following reconstructive surgery postmastectomy remains high, despite the use of prophylactic antibiotic strategies. Thus, surgeons have begun using additional antibiotic-based prevention strategies, including triple antibiotic pocket irrigants (TAPIs). However, these strategies fail to reduce BIAI rates for these patients. To understand why these therapies fail, we assessed the antimicrobial resistance patterns of Staphylococcus aureus strains, the most common cause of BIAI, to the antibiotics in TAPI (bacitracin, cefazolin, and gentamicin). We found that while clinically relevant BIAI isolates were more susceptible to the individual antibiotics compared to a reference strain, TAPI was effective at killing all the strains in vitro. However, in a mouse model, the BIAI isolates displayed recalcitrance to TAPI, which contrasted with the reference strain, which was susceptible. These data suggest that strains causing BIAI may encode specific recalcitrance mechanisms not present within reference strains.

Analysis of pathogen distribution and antimicrobial resistance at infected sites in plastic surgery

OBJECTIVE

By analyzing the distribution and drug resistance of common pathogen in different sites in plastic surgery to provide reference for clinicians to choose the best antibacterial treatment plan.

METHODS

Pathogens of postoperative infection in plastic surgery from January 2011 to December 2021 were retrospectively analyzed to determine the species and quantity, and to access the trend of each pathogen's detection rate. The antibiotic sensitivity and distribution characteristics of common pathogens were studied in conjunction with the site of infection.

RESULTS

A total of 1709 bacterial strains were detected, including 1244 gram-positive bacterial strains and 465 gram-negative bacterial strains. The main pathogen of perineum was Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), while Staphylococcus aureus (S. aureus) was the most common pathogen in the other infected sites. The detection rate of methicillin-resistant S. aureus (MRSA) and methicillin-resistant coagulase-negative staphylococcus (MRCNS) was on the rise from 2011 to 2021. No S. aureus and coagulase-negative staphylococcus (CoNS) strains were resistant to vancomycin. The sensitive rate of S. aureus from all parts and CoNS from all sites except lower limbs and mandible was higher than 80% to linezolid. The resistance rate of S. aureus and CoNS in all parts to penicillin, clindamycin, and erythromycin was high. The susceptibility rate of CoNS in lower mandible was high to gentamicin.

CONCLUSIONS

Staphylococcus aureus was the primary pathogen of gram-positive bacteria in all site of plastic surgery except perineum, followed by CoNS. The distribution and drug resistance of pathogen in different infection sites were different. We should formulate more accurate and reasonable antibacterial programs according to drug resistance results of various parts to reduce the emergence of resistant strains and effectively prevent and control infection.

Pharmacological Approaches for the Prevention of Breast Implant Capsular Contracture

Capsular contracture is a common complication associated with breast implants following reconstructive or aesthetic surgery in which a tight or constricting scar tissue capsule forms around the implant, often distorting the breast shape and resulting in chronic pain. Capsulectomy (involving full removal of the capsule surrounding the implant) and capsulotomy (where the capsule is released and/or partly removed to create more space for the implant) are the most common surgical procedures used to treat capsular contracture. Various structural modifications of the implant device (including use of textured implants, submuscular placement of the implant, and the use of polyurethane-coated implants) and surgical strategies (including pre-operative skin washing and irrigation of the implant pocket with antibiotics) have been and/or are currently used to help reduce the incidence of capsular contracture. In this article, we review the pharmacological approaches-both commonly practiced in the clinic and experimental-reported in the scientific and clinical literature aimed at either preventing or treating capsular contracture, including (i) pre- and post-operative intravenous administration of drug substances, (ii) systemic (usually oral) administration of drugs before and after surgery, (iii) modification of the implant surface with grafted drug substances, (iv) irrigation of the implant or peri-implant tissue with drugs prior to implantation, and (v) incorporation of drugs into the implant shell or filler prior to surgery followed by drug release in situ after implantation.

Characterization of host-pathogen-device interactions in Pseudomonas aeruginosa infection of breast implants

BACKGROUND

Pseudomonas aeruginosa (PA) accounts for 7%-22% of breast implant-associated infections (BIAIs), which can result in reconstructive failures and explantation. Investigating host-pathogen-device interactions in mice and patient samples will improve our understanding of colonization mechanisms, for targeted treatments and clinical guidelines.

METHODS

Mice with and without implants (Mentor®) were infected with PAO1 lab strain or BIP2 or BIP16 clinical strains and sacrificed at 1 day or 7 days post-infection (dpi) to evaluate for colonization of implants and underlying tissues via colony-forming unit (CFU) enumeration. Immunostaining was performed on mouse implants, human tissue expanders (TE) colonized by BIP2, and acellular dermal matrix (ADM) colonized by BIP16.

RESULTS

Colonization of tissues and smooth implants by P. aeruginosa was strain-dependent: at 1dpi, all strains acutely infected tissues with and without implants with colonization levels reflecting growth rates of individual strains. At 7dpi, PAO1 caused colonization of ~105 CFUs/100mg of tissue but required implant presence, while in mice infected with BIP2/BIP16, CFUs were below the limit of detection with or without implants. Immunofluorescence staining of mouse implants, however, demonstrated continued presence of BIP2 and BIP16. Staining showed co-localization of all strains with fibrinogen, collagen I and collagen III on mouse and human samples.

CONCLUSIONS

The trajectory of P. aeruginosa in BIAIs was strain-dependent and strains could exhibit acute symptomatic or chronic asymptomatic colonization. With strains causing clinical symptoms, the presence of an implant significantly worsened infection. For asymptomatic colonizers, further studies investigating their long-term impacts, especially during periods of immunosuppression in hosts, are needed.

In Vitro Evaluation of Common Antimicrobial Solutions Used for Breast Implant Soaking and Breast Pocket Irrigation-Part 2: Efficacy Against Biofilm-Associated Bacteria

Background

Biofilm-associated bacteria have been observed in both breast implant revision and tissue expander-implant exchange surgeries. The utilization of antimicrobial solutions in breast surgery, especially those containing triple antibiotics (TAB) and/or 10% povidone-iodine (PI), may help reduce existing biofilm-associated bacteria, which is particularly important in a mature breast pocket that may contain residual bacteria from a previously colonized implant surface or, theoretically, bacteria that may arrive postoperatively through hematogenous spread.

Objectives

A series of in vitro assessments was performed to evaluate the antimicrobial utility of TAB and PI, either alone or in combination, against preformed biofilm-associated bacteria.

Methods

Preformed biofilm-associated gram-positive and gram-negative bacterial strains were exposed to TAB and PI ± TAB for up to 30 minutes in a bacterial time-kill assay. Efficacy of various dilutions of PI and the effects of serum protein on PI efficacy were also investigated.

Results

TAB was ineffective at the timeframes tested when utilized alone; when utilized in conjunction with PI, significant log reduction of all biofilm-associated bacterial species tested was achieved when treated for at least 5 minutes. PI alone at a concentration of 25% or higher was also effective, although its efficacy was negatively affected by increasing serum protein concentration only for Staphylococcus epidermidis.

Conclusions

Our data indicate that PI-containing solutions significantly reduce biofilm-associated bacteria, suggesting potential utility for breast pocket irrigation during revision or exchange surgeries. Care should be taken to minimize excessive dilution of PI to maintain efficacy.

Surgical Treatment of Capsular Contracture (CC): Literature Review and Outcomes Utilizing Implants in Revisionary Surgery

BACKGROUND

The objective of this clinical review is to provide an overview of the use of breast implants after capsular contracture (CC) surgical treatment, with a focus on type of implants used. Furthermore, our experience in this field is also reviewed.

METHODS

MEDLINE, EMBASE, Web of Science, Scopus, the Cochrane Central, and Google Scholar databases were reviewed to identify literature related to surgical treatment of capsular contracture and implant replacement. Each article was reviewed by two independent reviewers to ensure all relevant publications were identified. The literature search identified 54 applicable articles. Of these, 26 were found to have a therapeutic level of evidence. The reference lists in each relevant paper were screened manually to include relevant papers not found through the initial search.

RESULTS

Only four articles report the replacement of implants after surgical treatment of capsular contracture. Six articles reported an implant exchange with only smooth silicone gel filled implants. Two reviews advice to use smooth implants in implant replacement.

CONCLUSION

With our expertise in the field and the results of this up-to-date literature review, it can be concluded that implant exchange is recommended in case of breast revision for capsular contracture, and the use of subpectoral smooth silicone gel breast implants is a good option after surgical treatment in patients with primary or recurrence Baker III-IV.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Current Concepts in Capsular Contracture: Pathophysiology, Prevention, and Management

Over 400,000 women in the United States alone will have breast implant surgery each year. Although capsular contracture represents the most common complication of breast implant surgery, surgeons continue to debate the precise etiology. General agreement exists concerning the inflammatory origin of capsular fibrosis, but the inciting events triggering the inflammatory cascade appear to be multifactorial, making it difficult to predict why one patient may develop capsular contracture while another will not. Accordingly, researchers have explored many different surgical, biomaterial, and medical therapies to address these multiple factors in an attempt to prevent and treat capsular contracture. In the current paper, we aim to inform the reader on the most up-to-date understanding of the pathophysiology, prevention, and treatment of capsular contracture.

Characterizing the Microbiome of the Contracted Breast Capsule Using Next Generation Sequencing

BACKGROUND

Recent work suggests that bacterial biofilms play a role in capsular contracture (CC). However, traditional culture techniques provide only a limited understanding of the bacterial communities present within the contracted breast. Next generation sequencing (NGS) represents an evolution of polymerase chain reaction technology that can sequence all DNA present in a given sample.

OBJECTIVES

The aim of this study was to utilize NGS to characterize the bacterial microbiome of the capsule in patients with CC following cosmetic breast augmentation.

METHODS

We evaluated 32 consecutive patients with Baker grade III or IV CC following augmentation mammoplasty. Specimens were obtained from all contracted breasts (n = 53) during capsulectomy. Tissue specimens from contracted capsules as well as intraoperative swabs of the breast capsule and implant surfaces were obtained. Samples were sent to MicroGenDX Laboratories (Lubbock, TX) for NGS.

RESULTS

Specimens collected from 18 of 32 patients (56%) revealed the presence of microbial DNA. The total number of positive samples was 22 of 53 (42%). Sequencing identified a total of 120 unique bacterial species and 6 unique fungal species. Specimens with microbial DNA yielded a mean [standard deviation] of 8.27 [4.8] microbial species per patient. The most frequently isolated species were Escherichia coli (25% of all isolates), Diaphorobacter nitroreducens (12%), Cutibacterium acnes (12%), Staphylococcus epidermidis (11%), fungal species (7%), and Staphylococcus aureus (6%).

CONCLUSIONS

NGS enables characterization of the bacterial ecosystem surrounding breast implants in unprecedented detail. This is a critical step towards understanding the role this microbiome plays in the development of CC.

LEVEL OF EVIDENCE: 4

Review of silicone surface modification techniques and coatings for antibacterial/antimicrobial applications to improve breast implant surfaces

Silicone implants are widely used in the medical field for plastic or reconstructive surgeries for the purpose of soft tissue issues. However, as with any implanted object, healthcare-associated infections are not completely avoidable. The material suffers from a lack of biocompatibility and is often subject to bacterial/microbial infections characterized by biofilm growth. Numerous strategies have been developed to either prevent, reduce, or fight bacterial adhesion by providing an antibacterial property. The present review summarizes the diverse approaches to deal with bacterial infections on silicone surfaces along with the different methods to activate/oxidize the surface before any surface modifications. It includes antibacterial coatings with antibiotics or nanoparticles, covalent attachment of active bacterial molecules like peptides or polymers. Regarding silicone surfaces, the activation step is essential to render the surface reactive for any further modifications using energy sources (plasma, UV, ozone) or chemicals (acid solutions, sol-gel strategies, chemical vapor deposition). Meanwhile, corresponding work on breast silicone prosthesis is discussed. The latter is currently in the line of sight for causing severe capsular contractures. Specifically, to that end, besides chemical modifications, the antibacterial effect can also be achieved by physical surface modifications by adjusting the surface roughness and topography for instance.

The Microbiota of the Human Mammary Ecosystem

Human milk contains a dynamic and complex site-specific microbiome, which is not assembled in an aleatory way, formed by organized microbial consortia and networks. Presence of some genera, such as Staphylococcus, Streptococcus, Corynebacterium, Cutibacterium (formerly known as Propionibacterium), Lactobacillus, Lactococcus and Bifidobacterium, has been detected by both culture-dependent and culture-independent approaches. DNA from some gut-associated strict anaerobes has also been repeatedly found and some studies have revealed the presence of cells and/or nucleic acids from viruses, archaea, fungi and protozoa in human milk. Colostrum and milk microbes are transmitted to the infant and, therefore, they are among the first colonizers of the human gut. Still, the significance of human milk microbes in infant gut colonization remains an open question. Clinical studies trying to elucidate the question are confounded by the profound impact of non-microbial human milk components to intestinal microecology. Modifications in the microbiota of human milk may have biological consequences for infant colonization, metabolism, immune and neuroendocrine development, and for mammary health. However, the factors driving differences in the composition of the human milk microbiome remain poorly known. In addition to colostrum and milk, breast tissue in lactating and non-lactating women may also contain a microbiota, with implications in the pathogenesis of breast cancer and in some of the adverse outcomes associated with breast implants. This and other open issues, such as the origin of the human milk microbiome, and the current limitations and future prospects are addressed in this review.

Doxycycline-Coated Silicone Breast Implants Reduce Acute Surgical-Site Infection and Inflammation

BACKGROUND

Surgical-site infection after implant-based breast reconstruction remains a leading cause of morbidity. Doxycycline is an antibiotic used to treat soft-tissue infections. The authors hypothesize that doxycycline-coated breast implants will significantly reduce biofilm formation, surgical-site infection, and inflammation after bacterial infection.

METHODS

Pieces of silicone breast implants were coated in doxycycline. In vitro studies to characterize the coating include Fourier transmission infrared spectroscopy, elution data, and toxicity assays (n = 4). To evaluate antimicrobial properties, coated implants were studied after methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa inoculation in vitro and in a mouse model at 3 and 7 days (n = 8). Studies included bacterial quantification, cytokine profiles, and histology.

RESULTS

Coated silicone breast implants demonstrated a color change, increased mass, and Fourier transmission infrared spectroscopy consistent with a doxycycline coating. Coated implants were nontoxic to fibroblasts and inhibited biofilm formation and bacterial adherence after MRSA and P. aeruginosa incubation in vitro, and measurable doxycycline concentrations at 24 hours were seen. In a mouse model, a significant reduction of MRSA and P. aeruginosa bacterial colonization after 3 and 7 days in the doxycycline-coated implant mice was demonstrated when compared to the control mice, control mice treated with intraperitoneal doxycycline, and control mice treated with a gentamicin/cefazolin/bacitracin wash. Decreased inflammatory cytokines and inflammatory cell infiltration were demonstrated in the doxycycline-coated mice.

CONCLUSIONS

A method to coat silicone implants with doxycycline was developed. The authors' doxycycline-coated silicone implants significantly reduced biofilm formation, surgical-site infections, and inflammation. Further studies are needed to evaluate the long-term implications.

The Efficacy of Breast Implant Irrigant Solutions: A Comparative Analysis Using an In Vitro Model

BACKGROUND

Infections are challenging complications of implant-based breast reconstruction and augmentation. They pose a clinical challenge, with significant economic implications. One proposed solution is implant irrigation at the time of placement. There is no consensus on the optimal irrigant solution.

METHODS

The authors tested the relative efficacy of 10% povidone-iodine, Clorpactin, Prontosan, triple-antibiotic solution, or normal saline (negative control) against two strains each of methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. Sterile, smooth silicone implant disks were immersed in irrigant solution, then incubated in suspensions of methicillin-resistant S. aureus or S. epidermidis overnight. The disks were rinsed and sonicated to displace adherent bacteria from the implant surface, and the displaced bacteria were quantified. Normalized values were calculated to characterize the relative efficacy of each irrigant.

RESULTS

Povidone-iodine resulted in reductions of the bacterial load by a factor of 10 to 10 for all strains. Prontosan-treated smooth breast implant disks had a 10-fold reduction in bacterial counts for all but one methicillin-resistant S. aureus strain. In comparison to Prontosan, triple-antibiotic solution demonstrated a trend of greater reduction in methicillin-resistant S. aureus bacterial load and weaker activity against S. epidermidis strains. Clorpactin reduced the recovered colony-forming units for only a single strain of S. epidermidis. Povidone-iodine demonstrated the greatest efficacy against all four strains. However, Clorpactin, triple-antibiotic solution, and Prontosan demonstrated similar efficacies.

CONCLUSIONS

Povidone-iodine was the most efficacious of the irrigants at reducing methicillin-resistant S. aureus and S. epidermidis contamination. Given the recent lifting of the U.S. Food and Drug Administration moratorium, larger clinical studies of povidone-iodine as a breast implant irrigant solution are warranted.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Establishment and Characterization of Bacterial Infection of Breast Implants in a Murine Model

BACKGROUND

Staphylococcus epidermidis and Pseudomonas aeruginosa are the most common causes of Gram-positive and Gram-negative breast implant-associated infection. Little is known about how these bacteria infect breast implants as a function of implant surface characteristics and timing of infection.

OBJECTIVES

The aim of this work was to establish a mouse model for studying the impact of various conditions on breast implant infection.

METHODS

Ninety-one mice were implanted with 273 breast implant shells and infected with S. epidermidis or P. aeruginosa. Smooth, microtextured, and macrotextured breast implant shells were implanted in each mouse. Bacterial inoculation occurred during implantation or 1 day later. Implants were retrieved 1 or 7 days later. Explanted breast implant shells were sonicated, cultured, and colony-forming units determined or analyzed with scanning electron microscopy.

RESULTS

P. aeruginosa could be detected on all device surfaces at 1- and 7- days post infection (dpi), when mice were implanted and infected concurrently or when they were infected 1- day after implantation. However, P. aeruginosa infection was more robust on implant shells retrieved at 7 dpi and particularly on the macrotextured devices that were infected 1 day post implantation. S. epidermidis was mostly cleared from implants when mice were infected and implanted concurrently. Other the other hand, S. epidermidis could be detected on all device surfaces at 1 dpi and 2 days post implantation. However, S. epidermdis infection was suppressed by 7 dpi and 8 days post implantation.

CONCLUSIONS

S. epidermidis required higher inoculating doses to cause infection and was cleared within 7 days. P. aeruginosa infected at lower inoculating doses, with robust biofilms noted 7 days later.

Deposition of Host Matrix Proteins on Breast Implant Surfaces Facilitates Staphylococcus Epidermidis Biofilm Formation: In Vitro Analysis

BACKGROUND

Staphylococcus epidermidis is a primary cause of breast implant-associated infection. S epidermidis possesses several virulence factors that enable it to bind both abiotic surfaces and host factors to form a biofilm. In addition S epidermidis colocalizes with matrix proteins coating explanted human breast implants.

OBJECTIVES

The authors sought to identify matrix proteins that S epidermidis may exploit to infect various breast implant surfaces in vitro.

METHODS

A combination of in vitro assays was used to characterize S epidermidis strains isolated from human breast implants to gain a better understanding of how these bacteria colonize breast implant surfaces. These included determining the (1) minimum inhibitory and bactericidal concentrations for irrigation solutions commonly used to prevent breast implant contamination; (2) expression and carriage of polysaccharide intercellular adhesin and serine-aspartate repeat proteins, which bind fibrinogen (SdrG) and collagen (SdrF), respectively; and (3) biofilm formation on varying implant surface characteristics, in different growth media, and supplemented with fibrinogen and Types I and III collagen. Scanning electron microscopy and immunofluorescence staining analyses were performed to corroborate findings from these assays.

RESULTS

Textured breast implant surfaces support greater bacterial biofilm formation at baseline, and the addition of collagen significantly increases biomass on all surfaces tested. We found that S epidermidis isolated from breast implants all encoded SdrF. Consistent with this finding, these strains had a clear affinity for Type I collagen, forming dense, highly structured biofilms in its presence.

CONCLUSIONS

The authors found that S epidermidis may utilize SdrF to interact with Type I collagen to form biofilm on breast implant surfaces.

LEVEL OF EVIDENCE: 5

Extended Prophylactic Antibiotics for Mastectomy with Immediate Breast Reconstruction: A Meta-analysis

Supplemental Digital Content is available in the text.

Background:

The risk of surgical site infection (SSI) for breast surgery in patients without additional risk factors is low, below 5%. Evidence shows the risk of SSI is significantly elevated in patients undergoing immediate breast reconstruction (IBR). However, there is no consensus regarding the use of extended antibiotic prophylaxis. We aim to determine the effect of extended antibiotic prophylaxis on the incidence of SSI after IBR.

Methods:

PubMed and Scopus were searched by 2 independent reviewers. Data abstracted included types of study, basic characteristics, detailed antibiotic prophylaxis information, SSI event, and other secondary outcomes. We calculated the risk ratio (RR) and 95% confidence interval (CI) for each study and used a random-effects model to estimate the results. Study quality, bias, and heterogeneity were also analyzed.

Results:

A total of 11 studies (15,966 mastectomy procedures) were included. We found an overall 5.99% SSI rate in our population. Three studies comparing topical antibiotics with no topical antibiotics demonstrated statistical significance (RR = 0.26, 95% CI: 0.12–0.60, P = 0.001), whereas 8 studies comparing extended systemic antibiotics with standard of care found no statistical significance (RR = 0.80, 95% CI: 0.60–1.08, P = 0.13).

Conclusions:

In the setting of IBR following mastectomy, there is insufficient evidence for the use of extended prophylactic antibiotics to reduce SSI rates. Well-designed randomized controlled trials in patients undergoing IBR should be conducted to determine the appropriate regimen and/or duration of prophylactic antibiotics on SSI outcomes.