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

Results

The average age of patients was 48.4 years (range from 27 to 64 years, median 49.0). The mean body mass index (BMI) was 26.1 kg/m² (range from 17.7 to 35.2, median 26.1). In 6.4% of patients, diabetes was confirmed, and 4.3% of them were active smokers. Among the patients, eight (17.0%) were MSSA carriers; none of them was a carrier of MRSA. The average time before removal of the implant was 601 days (range 14–9102, median 113 days). The average follow-up time was 601 days. More than half of the patients have an increased BMI, about 1/3 of them received pre-operative radiotherapy; there were active smokers and people with diabetes. The coexistence of recognized risk factors increased the danger of infection. The detailed clinical characteristics of patients are presented in Table II.

Discussion

In this study, we show that infections were the most common reason of the removal of the implants after generative treatment in breast cancer and were responsible for the loss of the implant in 83.0% of the cases analyzed. The prevalence of breast implant infection in this study was 6.0% of implantation. Of the infections diagnosed, 87.0% appeared within one year of implantation; however, less than half of the infections developed within 90 days of the reconstructive surgery, while up to 30 days – about 13.0% of infections were diagnosed. Non-infectious complications caused the loss of the implant in about 15.0% of the cases analyzed.

In the available literature, infection after the breast reconstruction surgery appeared with varying frequency and their etiological agents were different. This is related to the adopted definition of infection, the period of time for surveillance, the perioperative prophylaxis applied, and the composition of microbiota inhabiting the operated area (Weichman et al. 2013). The time of observation significantly influences the obtained results. In the studies of (Olsen et al. 2017) on a large group of respondents, approximately 17 000 patients undergoing mastectomy, the incidence of SSI up to 90 days after surgery was 3.2–8.9% and was dependent on the type of reconstruction. In the opinion of the authors cited, it is necessary to carry out the infection surveillance up to 90 days after surgery, since the shorter period of observation, limited to 30 days, leads to an underestimation of the rate of infection. Similarly, (Lankiewicz et al. 2012) found, however, on a smaller group of patients comprised of 54 women undergoing mastectomy with immediate reconstruction with an implant, that only about 1/2 of the diagnosed SSI developed within 30 days after surgery. (Viola et al. 2016), in single-center retrospective studies involving over 3000 patients, found that only 30.0% of all SSIs were diagnosed within the first 30 days after a simultaneous reconstruction using a tissue expander. In our work, we found lower rates than the quoted authors (Lankiewicz et al., 2012; Viola et al. 2016) regarding infection within 30 days after reconstructive surgery. When we limited observation to one month after the procedure we were able to detect only 1/8 of the implant infections confirmed.

The reasons for the variability in the period when the infections appeared were probably related to the eligibility criteria for the reconstructive surgery (the patient’s profile), the type of surgery performed, the experience of the center performing the implant treatments, as well as the prophylactic treatment used. In our work, we confirmed that the observation of infections limited to 30 days after surgery was insufficient, as was the 90-days observation. It seems that the optimal time could be a one-year observation. In our study, this allowed the detection of approximately 90% of infections. The necessity to monitor for complications after breast reconstruction during one year after surgery, instead of 30 days, has also been indicated by other researchers (Blough et al. 2018), who used individualized tools to assess the risk of post-surgery complications within one year of breast reconstruction.

The fact that the number of infections within 30 days in the cases we analyzed was lower than the numbers appearing in the studies already published may be related to the strict epidemiological supervision carried out in our hospital and the prophylaxis to prevent perioperative infections.

According to the hospital antibiotic policy, the patients studied in the current work received prophylactically a first generation cephalosporin in therapy extended for five days, or until the drain was removed due to the increased SSI risk associated with drainage (Araco et al. 2007). However, currently, many authors advise against such a procedure, pointing to the side effects that accompany it, namely the increase in resistance among microorganisms responsible for SSI (McCullough et al. 2016). In accordance with the idea of perioperative prophylaxis, a single dose of the first-generation cephalosporin is sufficient to ensure the proper concentration of the antibiotic at the incision site and to prevent infections mainly caused by methicillin-sensitive staphylococci (Pittet et al. 2005). Under the recommendations of scientific societies, it is also not suggested to continue treatment with antibiotics after discharge from the hospital, and the guidelines of the American Society of Plastic Surgeons recommend discontinuation of antibiotics at 24 hours after surgery. Nevertheless, a review of publications (Phillips et al. 2016; Viola et al. 2016) shows that the use of prolonged antibiotic therapy by surgeons, both during hospitalization and after discharge from the hospital, is quite common.

In addition to the prophylactic use of antibiotics, a screening test for S. aureus was introduced as a standard in our hospital. When colonization with MRSA strain is confirmed, mupirocin is applied nasally without performing tests confirming the effectiveness of eradication. However, in the cases analyzed in the current work, no MRSA carriers were found. Whereas, concerning the colonization with MSSA strains, we assumed that the perioperative prophylaxis with the first-generation cephalosporin is sufficient protection, with its MSSA spectrum of action. It should be emphasized that screening for S. aureus in the group of patients undergoing reconstruction is not recommended. According to the recommendations for microbiological screening tests in hospitalized patients (Fleischer et al. 2017), investigation for the carriage of S. aureus is recommended only before cardiac surgery, implantation of joint prostheses and spine procedures, as well as in centers with incidence of SSI caused by S. aureus higher than the average reported in literature, mainly in neurosurgery and vascular surgery. Patients qualified for breast reconstruction do not meet the criteria given in these recommendations. Nevertheless, within the framework of the perioperative infections prevention carried out in our center, such examination was undertaken. In the current work, we diagnosed MSSA carriers in 17.0% of the cases. In one case, the host had to remove the implant 14 days after surgery due to infection caused by S. aureus. In other cases, the infection caused by MSSA occurred in the late period, on average more than one year after surgery, similarly as in a patient with an MRSA-induced infection.

In the available literature on implant infections, among the etiological agents of infections after breast reconstruction, the microbiota of the skin and at the mouth of the milk ducts were isolated (coagulase-negative Staphylococcus, mainly S. epidermidis and coagulase-positive S. aureus) (Chidester et al. 2016; McCullough et al. 2016; Viola et al. 2016). These species adhere to the smooth surfaces of biomaterials, and may also colonize the skin. They demonstrate the ability to form a biofilm, which protects them against the host’s immune system and antibiotics (Vacheethasanee et al. 1998; Costerton et al. 1999; Chessa et al. 2016; Conte et al. 2018).

In our work, staphylococci constituted 50% of the isolated microorganisms. They were in a lower percentage than in the studies by (Seng et al. 2015) but similar to the results obtained in (Song et al. 2017) (respectively: 71.0%, and 50.0%). In three cases (9.4%), we isolated E. faecalis that can adhere, modify the immune response, and form biofilms (Prażmo et al. 2016); however, these species are rarely the etiological agent of implant infections. In the available literature, one can find only a few reports about the participation of these microorganisms in wound infections after immediate breast reconstruction (Abedi et al. 2016).

The incidence of infections caused by Gram-negative rods is varied. In the work of Feldman et al. (Feldman et al. 2010) concerning early infections of breast implants, Gram-negative rods accounted for 6.0% of the microorganisms isolated. (Seng et al. 2015) also confirmed the participation of these bacteria in implant infections: Gram-negative rods were identified in 27.0% of cases, and P. aeruginosa was the second most commonly isolated microorganism. In turn, in the work of (Chidester et al. 2016) P. aeruginosa was the most common causative agent of infections and accounted for 26.8% of them. Research carried out by (Song et al. 2017) indicates the involvement of A. baumanii in infections alongside with P. aeruginosa.

In our work more frequently than in the previous studies (Feldman et al. 2010; Seng et al. 2015; Chidester et al. 2016; Song et al. 2017), Gram-negative bacilli were isolated. They constituted a total of 40.6% of the bacterial isolates. The most commonly isolated rods were E. cloacae (18.8%), and P. aeruginosa (12.5%). These microorganisms secrete extracellular polymers forming a complex matrix of biofilm. The biofilm matrix plays an important role in survival in tissues and evading the response of the body’s immune system, which promotes the development of the infection despite the use of antibiotics (Donlan and Costerton 2002). The occurrence of Gram-negative bacilli, naturally resistant to the first-generation cephalosporin, may be associated with the perioperative prophylaxis. Our work did not show the dependence of the etiology of microorganisms (cocci vs. rods) on the type of reconstruction or oncological treatment.

Polybacterial infections are not associated with implants. However, in this work, in four cases (14.3%) we showed the presence of the polybacterial infections. Similar results were obtained by (Seng et al. 2015), as well as (Viola et al. 2016), the percentage of polybacterial infections reached 19.0 and 17.0%, respectively, among all diagnosed infections. In the cases analyzed by us, two polybacterial infections related to patients treated with radiotherapy. Radiotherapy is an important risk factor for the occurrence of infection through damage to the skin and other tissues, which may affect the microbiota. In over 1/3 of cases, the adjuvant treatment was radiotherapy (in 14 cases before reconstruction surgery, in 2 cases after surgery). However, in only one case for the reconstruction of the breast beside the implantation, autologous tissues were used (lobe from the latissimus dorsi muscle). According to the current standard of diagnostic and therapeutic procedures, this is the recommended method of treatment (Bocian et al. 2016). This indicates the need to use more complex restorative treatments in the future (especially the use of flap techniques in patients requiring radiation therapy).

The existence of a significant risk of complications (especially infectious) related to radiotherapy was shown by (Jagsi et al. 2016) and among the most common adverse effects, they mention an increased risk of wound infection between 7 and 24 months after surgery, and consequently the requirement to remove the implant. Similar observations were also presented by other authors (Momoh et al. 2014; Blough et al. 2018). In our work, the median time to remove the implant after using radiotherapy was 3–4 months after surgery.

In addition to radiotherapy, factors that increase the risk of infection complications according to Warren (Peled et al. 2010) also include adjuvant chemotherapy. However, in newer works, this relationship is not shown. The lack of influence of the time of the chemotherapy administration on the risk of SSI (pre-operative vs. post-operative vs. pre- and post- vs. non-chemotherapy) was demonstrated by (Chattha et al. 2018).

In approximately 1/6 of the cases discussed by us, there was no confirmation of microbiological infection, despite the presence of clinical symptoms of wound infection. The probable cause of the negative culture results was an occurrence of rare microorganisms, which do not grow on classical microbiological media and also difficulty in culturing microorganisms present in biofilms or the presence of microorganisms with special nutritional requirements (Pajkos et al 2003). This is confirmed by the results of the research made using molecular biology methods. The use of molecular techniques as well as gene sequencing omits the culture and leads to an increase in the recognition of infections (Romero et al. 2017). Management of infections in oncological patients should now include extended microbiological diagnostics to detect hard growing or non-cultivated microorganisms (Pittet et al. 2005; Al-Halabi et al. 2018).

Infections remain the most common reason for removing implants and are a serious complication of reconstruction during the treatment of breast cancer. The existence of risk factors for infection, the diversity of bacterial species that cause the implant infection, their potential for biofilm formation and natural resistance to selected groups of antibiotics, as well as the long time of infection development pose a great challenge for the effective treatment of implant infections, which in turn leads to the removal of the implant. The introduction of standardized data collection protocols in the prospective studies, especially in specialized breast cancer centers, may be helpful in the identification of the factors that increase the risk of surgical site infection after reconstruction, determination the etiology of infections, establishment of the optimal perioperative prophylaxis, in empirical therapy, as well as in post-hospital outpatient care. This should result in lower SSI rates.

Ethical approval

The study proposal was approved by the Bioethics Committee of the Collegium Medicum of Nicolaus Copernicus University in Bydgoszcz, No KB 286/2019.

ORCID

Maria Szymankiewicz 0000-0003-3669-6903