Nontuberculous Mycobacterial Infections After Silicone Breast Implant Reconstruction Emphasize a Diversity of Infecting Mycobacteria

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Inflammatory Lesions of the Breast

CONTEXT.—

Inflammatory lesions of the breast are rare but not infrequently pose problems both clinically and morphologically, particularly on needle core biopsies. These lesions range from acute inflammatory conditions to chronic lymphoplasmacytic and lymphohistiocytic to granulomatous inflammatory diseases.

OBJECTIVE.—

To provide a comprehensive overview of inflammatory lesions of the breast, with etiopathogenesis and clinical, radiologic, and pathologic features as well as differential diagnostic considerations, clinical management, and prognosis.

DATA SOURCES.—

The existing literature in the English language, including original research articles and review articles describing inflammatory lesions of the breast.

CONCLUSIONS.—

Inflammatory lesions of the breast are characterized by a wide variety of clinical, radiologic, and morphologic features. The histopathologic differential diagnosis often includes a neoplastic process requiring ancillary studies and correlation with clinical and radiologic findings. Although most specimens display nonspecific findings precluding a definitive pathologic diagnosis, pathologists have a unique opportunity to play a crucial role in identifying key histologic features suggestive of certain entities, such as cystic neutrophilic granulomatous mastitis, immunoglobulin (Ig) G4 mastitis, or squamous metaplasia of lactiferous ducts, in the right clinical and radiologic context, and thereby guiding optimal and timely clinical management. The information presented herein will be helpful to practicing anatomic pathologists and pathology trainees in becoming more familiar with specific morphologic features and overcoming differential diagnostic challenges related to pathology reporting of inflammatory lesions of the breast.

Characterization of Biofilm Formation by Mycobacterium chimaera on Medical Device Materials

Non-tuberculous mycobacteria (NTM) are widespread in the environment and are a public health concern due to their resistance to antimicrobial agents. The colonization of surgical heater-cooler devices (HCDs) by the slow-growing NTM species Mycobacterium chimaera has recently been linked to multiple invasive infections in patients worldwide. The resistance of M. chimaera to antimicrobials may be aided by a protective biofilm matrix of extracellular polymeric substances (EPS). This study explored the hypothesis that M. chimaera can form biofilms on medically relevant materials. Several M. chimaera strains, including two HCD isolates, were used to inoculate a panel of medical device materials. M. chimaera colonization of the surfaces was monitored for 6 weeks. M. chimaera formed a robust biofilm at the air-liquid interface of borosilicate glass tubes, which increased in mass over time. M. chimaera was observed by 3D Laser Scanning Microscopy to have motility during colonization, and form biofilms on stainless steel, titanium, silicone and polystyrene surfaces during the first week of inoculation. Scanning electron microscopy (SEM) of M. chimaera biofilms after 4 weeks of inoculation showed that M. chimaera cells were enclosed entirely in extracellular material, while cryo-preserved SEM samples further revealed that an ultrastructural component of the EPS matrix was a tangled mesh of 3D fiber-like projections connecting cells. Considering that slow-growing M. chimaera typically has culture times on the order of weeks, the microscopically observed ability to rapidly colonize stainless steel and titanium surfaces in as little as 24 h after inoculation is uncharacteristic. The insights that this study provides into M. chimaera colonization and biofilm formation of medical device materials are a significant advance in our fundamental understanding of M. chimaera surface interactions and have important implications for research into novel antimicrobial materials, designs and other approaches to help reduce the risk of infection.

Mycobacterium peregrinum Pacemaker Pocket Infection: A Case Report and Review of the Literature

Mycobacterium peregrinum is a rapidly growing mycobacterium (RGM), subspecies of Mycobacterium fortuitum complex, which can cause infections in the skin, surgical sites, and central lines. It has also been associated with implantable devices such as cardiac devices. Our objective is to present an atypical clinical case of M. peregrinum infection associated with a cardiac device, review the published literature, and highlight the importance of this type of RGM infection to enhance their therapeutic success. Only two other cases have been reported of M. peregrinum infection associated with cardiac devices. Diagnosis and treatment of Mycobacterium peregrinum infection can be challenging, and the literature is scarce. Better understanding and further research should be conducted regarding this infection.

A very rare case of mycobacterium gordonae infection of the breast

Mastitis is a common disease in women with both infectious and noninfectious causes. Most cases occur during lactation and are caused by Staphylococcus aureus and Streptococcus species; parasites and Mycobacteria have rarely been reported to cause breast infections (Mandell, Douglas, and Bennett's principles and practice of infectious diseases (9th edn);2019, Am J Respir Crit Care Med. 2007;175:367). Nontuberculous mycobacteria (NTM) which are also referred to as atypical mycobacteria, mycobacteria other than tuberculosis (MOTT), or environmental mycobacteria are a large group of Mycobacteria which are becoming increasingly common cause of infection all over the world (Arch Dermatol. 2006;142:1287). NTM can cause infection diseases especially in immunocompromised patients, such as HIV-positive hosts, most commonly in the lungs, skin and soft tissue, lymph nodes or rarely spread with multiorgan dissemination (Arch Plast Surg. 2014;41:759). Mycobacterium gordonae (M. gordonae) is a slow-growing atypical mycobacterium that is considered the least pathogenic NTM. The organism is ubiquitous, and mostly isolated from soil and water. Despite its nonvirulent nature, clinically significant infections have been reported also in some immunocompetent patients (J Formosan Med Assoc. 2020, Clin Infect Dis. 1992;1229). We report the first documented case of breast infection in a young immunocompetent woman sustained by Mycobacterium Gordonae.

Aspergillus fumigatus Spores Are Not Able to Penetrate Silicone Breast Implant Shells

INTRODUCTION

Bacterial contamination is hypothesized to be one reason for the development of capsular contracture after alloplastic breast reconstruction using silicone breast implants. The role of fungal colonization or infection in this context as well as the question if microorganisms can penetrate the shell of silicone breast implants remains an unresolved question to date. Therefore, the aim of this study was to assess whether fungal spores are able to penetrate the shell of silicone implants.

MATERIALS AND METHODS

In an experimental in vitro setup with different arrangements of growth compartments, silicone chambers were placed in culture dishes filled with Aspergillus minimal medium or liquid culture medium. Inoculation was performed with conidia of Aspergillus fumigatus and incubated for seven days. On a daily basis, plates were inspected for conidial germination and hyphal growth.

RESULTS

In none of the different experimental settings nutrients or hyphae of Aspergillus fumigatus were able to penetrate the silicone material.

CONCLUSIONS

Fungal spores and hyphae do not permeate through an intact silicone shell used in breast implants; thus, the silicone material serves as an impenetrable barrier.

Significance of Infections in Implant Loss After Breast Reconstruction in the Course of Breast Cancer Treatment

The aim of the study was to analyze the reasons for removing implants after breast reconstruction in the course of treatment of breast cancer. The study involved 428 patients, who underwent a total of 648 breast reconstruction procedures using artificial implants. 47 out of 648 cases (7.3%) were identified in which the implant had to be removed. Of the 47 cases, 57.4% had undergone deferred reconstruction, and 42.6% immediate reconstruction; 27.7% had undergone pre-operative chemotherapy and radiotherapy, 27.7% pre-operative chemotherapy, and 2.1% pre-operative radiotherapy; 6.4% were diabetic, 4.3% active smokers, and more than 50.0% had BMI greater than 25 kg/m². In 83.0% of the analyzed cases, the reason for removal of the implant was infection, in 8.5% it was local recurrence of breast cancer, in 4.3% it was damage (leakage) of the implant, and in 2.1% it was post-operative pain. About 87.0% of infections appeared within one year of implantation; however, less than a half developed within 90 days of the reconstructive surgery, and up to 30 days only about 13.0% had appeared. Among the etiological agents of infections were: coagulase-negative Staphylococcus (31.3%), Staphylococcus aureus (18.7%), Enterococcus faecalis (9.4%), Enterobacter cloacae (18.8%), Pseudomonas aeruginosa (12.5%), Acinetobacter lwoffii (3.1%), and other Gram-negative fermenting rods accounted for 6.2%. Infections were the most common reason for removing the implant after breast reconstruction. and occurred most often as late infections (>30 days after surgery). The time of observation for infectious complications should be at least 1 year.