PCR Characterization of Microbiota on Contracted and Non-Contracted Breast Capsules

A Systematic Review and Meta-Analysis of 16S rRNA and Cancer Microbiome Atlas Datasets to Characterize Microbiota Signatures in Normal Breast, Mastitis, and Breast Cancer

The breast tissue microbiome has been increasingly recognized as a potential contributor to breast cancer development and progression. However, inconsistencies in microbial composition across studies have hindered the identification of definitive microbial signatures. We conducted a systematic review and meta-analysis of 11 studies using 16S rRNA sequencing to characterize the bacterial microbiome in 1260 fresh breast tissue samples, including normal, mastitis-affected, benign, cancer-adjacent, and cancerous tissues. Studies published until 31 December 2023 were included if they analyzed human breast tissue using Illumina short-read 16S rRNA sequencing with sufficient metadata, while non-human samples, non-breast tissues, non-English articles, and those lacking metadata or using alternative sequencing methods were excluded. We also incorporated microbiome data from The Cancer Genome Atlas breast cancer (TCGA-BRCA) cohort to enhance our analyses. Our meta-analysis identified Proteobacteria, Firmicutes, Actinobacteriota, and Bacteroidota as the dominant phyla in breast tissue, with Staphylococcus and Corynebacterium frequently detected across studies. While microbial diversity was similar between cancer and cancer-adjacent tissues, they both exhibited a lower diversity compared to normal and mastitis-affected tissues. Variability in bacterial genera was observed across primer sets and studies, emphasizing the need for standardized methodologies in microbiome research. An analysis of TCGA-BRCA data confirmed the dominance of Staphylococcus and Corynebacterium, which was associated with breast cancer proliferation-related gene expression programs. Notably, high Staphylococcus abundance was associated with a 4.1-fold increased mortality risk. These findings underscore the potential clinical relevance of the breast microbiome in tumor progression and emphasize the importance of methodological consistency. Future studies to establish causal relationships, elucidate underlying mechanisms, and assess microbiome-targeted interventions are warranted.

Microbiome-Stealth Regulator of Breast Homeostasis and Cancer Metastasis

Cumulative evidence attests to the essential roles of commensal microbes in the physiology of hosts. Although the microbiome has been a major research subject since the time of Luis Pasteur and William Russell over 140 years ago, recent findings that certain intracellular bacteria contribute to the pathophysiology of healthy vs. diseased tissues have brought the field of the microbiome to a new era of investigation. Particularly, in the field of breast cancer research, breast-tumor-resident bacteria are now deemed to be essential players in tumor initiation and progression. This is a resurrection of Russel's bacterial cause of cancer theory, which was in fact abandoned over 100 years ago. This review will introduce some of the recent findings that exemplify the roles of breast-tumor-resident microbes in breast carcinogenesis and metastasis and provide mechanistic explanations for these phenomena. Such information would be able to justify the utility of breast-tumor-resident microbes as biomarkers for disease progression and therapeutic targets.

Impact of post-operative infection on revision procedures in breast reconstruction: A marketscan database analysis

BACKGROUND

Esthetic complications, such as capsular contracture and soft-tissue contour defects, hinder the desired outcomes of breast reconstruction. As subclinical infection is a prevailing theory behind capsular contracture, we investigated the effects of post-operative infections on these issues and revision procedures.

METHODS

We conducted a retrospective database study (2007-2021) on breast reconstruction patients from the MarketScan® Databases. Esthetic complications were defined by their associated revision procedures and queried via CPT codes. Severe capsular contracture (Grade 3-4) was defined as requiring capsulotomy or capsulectomy with implant removal or replacement. Moderate and severe soft-tissue defects were determined by the need for fat grafting or breast revision, respectively. Generalized linear models were used, adjusting for comorbidities and surgical factors (p < 0.05).

RESULTS

We analyzed the data on 62,510 eligible patients. Post-operative infections increased the odds of capsulotomy (OR 1.59, p < 0.001) and capsulectomy (OR 2.30, p < 0.001). They also raised the odds of breast revision for severe soft-tissue defects (OR 1.21, p < 0.001). There was no significant association between infections and fat grafting for moderate defects. Patients who had post-operative infections were also more likely to experience another infection after fat grafting (OR 3.39, p = 0.0018). In two-stage reconstruction, infection after tissue expander placement was associated with greater odds of infection after implant placement.

CONCLUSION

Post-operative infections increase the likelihood of developing severe soft-tissue defects and capsular contracture requiring surgical revision. Our data reinforce the role of infections in the pathophysiology of capsular contracture. Additionally, infections elevate the risk of subsequent infections after fat grafting for moderate defects, further increasing patient morbidity.

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.

From Salvage to Prevention: A Single-Surgeon Experience with Acellular Dermal Matrix and Infection in Prepectoral Breast Reconstruction

BACKGROUND

Increasing amounts of acellular dermal matrix are being used with the adoption of prepectoral breast reconstruction. Postoperative infection remains a challenge in breast reconstruction, and the contribution of acellular dermal matrix type, processing, and sterility assurance level to risk of complications in prepectoral reconstruction is not well studied.

METHODS

The authors performed a retrospective review of patients who underwent immediate prepectoral breast reconstruction from February of 2017 to July of 2020. Because of an increase in the rate of infection, the drain protocol was changed and acellular dermal matrix type was switched from AlloDerm (sterility assurance level, 10-3) to DermACELL (sterility assurance level, 10-6) in January of 2019. Demographic and surgical variables were collected, in addition to details regarding development and management of infection.

RESULTS

Despite higher rates of direct-to-implant reconstruction and bilateral procedures and increased implant volumes, the rate of infection was significantly lower in patients who received DermACELL instead of AlloDerm [two of 38 (5.3 percent) versus 11 of 41 (26.8 percent); p = 0.014]. Drain duration was slightly longer in the DermACELL group, consistent with the change in drain protocol. Baseline demographic and clinical characteristics remained similar between the two groups.

CONCLUSIONS

With increased reliance on large amounts of acellular dermal matrix for prepectoral breast reconstruction, it directly follows that the properties of acellular dermal matrix with respect to incorporation, sterility, and implant support are that much more important to consider. There have been few studies comparing different types of acellular dermal matrix in prepectoral breast reconstruction, and further research is required to determine the contribution of acellular dermal matrix type and processing techniques to development of postoperative infection.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

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.

Proper Skin Management in Breast Augmentation with a Periareolar Incision Prevents Implant Contamination and Biofilm-Related Capsular Contracture

BACKGROUND

Capsular contracture (CC) is a significant complication and major reason for revision in breast augmentation. Many studies indicate that most bacteria found in contracted capsules originate from the skin, especially that of the nipple-areolar complex (NAC). To prevent implant contamination, protocols without a periareolar incision have been proposed and have become a limitation for breast augmentation. We sought to propose a strategy of proper skin management for periareolar incisions to prevent implant contamination and biofilm-related CC.

METHODS

The analyses in this study are based on data collected from February 2017 to July 2020. A total of 129 patients were included, and they were randomized into two groups. The control group was subjected to no skin treatment before the surgery, and the treatment group underwent preoperative cleaning and disinfection of the NAC. We collected bacteriologic swabs used to rub the skin of the NAC and chest after draping and suturing from the control and treatment groups. We assessed the potential risk of detecting bacteria or fungi in the swabs, and we analyzed the data. The relationship between the positive culture rate and complication rate indicated the effectiveness of our strategy.

RESULTS

Initially, 774 swabs were obtained. In the control group, 6 swabs tested positive for pathogens, including 2 NAC swabs positive for Staphylococcus epidermidis (S. epidermidis) after draping and 3 and 1 NAC swabs positive for S. epidermidis and Staphylococcus aureus (S. aureus) after suturing, respectively. All the other samples in the control and treatment groups were negative for bacteria or fungi. All patients had at least 16 months of follow-up. No CC (Baker grades II-IV) was recorded during the follow-up, and the treatment group experienced a better outcome associated with a lower rate of minor complications.

CONCLUSIONS

Proper preoperative skin management helps keep the field pristine and potentially prevents implant contamination and even biofilm-related CC. With this strategy, breast augmentation using a periareolar incision or any other approach, even other surgery, could be a safe procedure.

LEVEL OF EVIDENCE IV

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 .

Is the skin microbiota a modifiable risk factor for breast disease?: A systematic review

PURPOSE

High prevalence, unreliable risk discrimination and poor clinical outcomes are observed in malignant and benign breast diseases (BD). The involvement of microbial communities in the development of BD has become topical, and distal influences of microbial dysregulation in the breast have been well established. Despite advances, the role of the breast skin microbiota in BD remains unclear. Interactions between the skin microbiota and the underlying mucosal immune system are complex. In homeostasis, the skin offers a physical barrier protecting underlying breast tissue from skin commensals and noxious environmental triggers. Our review aims to illuminate the role of the skin microbiota in the development of BD.

METHODS

Adhering to the PRISMA protocol, a systematic review was conducted utilising the Medline and Embase search engines.

RESULTS

Through a comprehensive search of the last ten years, twenty-two studies satisfied the inclusion criteria. Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were identified as the most prevalent phyla of both breast tissue and skin in healthy controls and BD. High abundance of skin commensals, specifically some species of Staphylococcus, have been linked in breast cancer and metastases. Similarly, dysregulated microbial abundance is also seen in inflammatory and implant-associated BD. These findings raise the hypothesis that the skin microbiota plays a role in tissue homeostasis and may contribute to a range of breast pathologies. Several mechanisms of microbial transfer to underlying tissue have been proposed, including retrograde transfer through ductal systems, breakdown of the skin barrier, and migration through nipple-aspirate fluid.

CONCLUSION

Our review provides preliminary insights into the skin microbiota as a modifiable risk factor for BD. This raises opportunities for future studies in antimicrobials/probiotics as an adjunct to, or replacement of surgery; a diagnostic and/or prognostic tool for BD; and the possibility of conditioning the microbiota to manage BD.

Capsular Contracture in Breast Implant Surgery: Where Are We Now and Where Are We Going?

Capsular contracture is the leading complication after surgery with breast implants. A lot of progress has been made investigating this complication over the years, and knowledge has been gained on this complication. Currently, the exact cause for capsular contracture is still unclear. It has been hypothesized that immunobiological factors (i.e., immunological and bacterial factors) and several risk factors play a central role in its development. In this paper, we give an overview of the known immunological factors that have been investigated in contracted and non-contracted capsules, as well as the role of bacterial formation around breast implants. We also report on risk factors that might increase the risk of capsular development. Lastly, it provides the latest research on this matter and discusses future perspectives as follow-up research is needed to unravel the pathogenic process leading to capsular contracture. This knowledge is of interest to establish medical therapies in order to prevent such side effects. Overall, capsular contracture seems to be a multifactorial condition consisting of several risk factors. LEVEL OF EVIDENCE V: 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 .

Microbial community compositions in breast implant biofilms associated with contracted capsules

Subclinical bacterial infections (biofilms) are strongly implicated in breast augmentation failure due to capsular contracture, and while these infections are generally ascribed to common skin commensals, this remains largely unsubstantiated through robust cultivation independent analyses. To determine capsule biofilm microbial community compositions, we employed amplicon sequencing of the 16S rRNA gene using DNA extracted from breast implant capsule samples. These cultivation independent analyses revealed that capsule associated biofilms are more diverse than canonical single-species infections, but have relatively low diversity (~ <100 species) compared to many host-associated microbial communities. In addition to taxa commonly associated with capsular contracture, the biofilms analyzed comprised a number of taxa that escaped detection in cultivation-dependent work. We have also isolated several key taxa identified through the culture-independent analyses. Together our analyses reveal that capsule biofilms are more diverse than cultivation studies suggest and can be heterogeneous within an individual capsule, between breasts of the same patient, across similar implant types, and over a range in severity of contracture. The complex nature of these communities requires further study across a broader suite of patients in addition to higher resolution analyses including metagenomics to better assess the fundamental role of microorganisms in 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

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.