Antibiotics for Spinal Cord Stimulation Trials and Implants: A Survey Analysis of Practice Patterns

Neuromodulation such as spinal cord stimulation (SCS), peripheral nerve stimulation (PNS), dorsal root ganglion stimulation (DRG), and intrathecal drug delivery (IDD) are common interventional and effective therapies for intractable neuropathic pain (1-5). Whereas the primary indications for spinal cord stimulation remain failed back surgery syndrome and complex regional pain syndrome, recent advances are widening indications of use including chronic intractable back pain without previous surgery where other treatments have failed (6-8). It is therefore likely that this treatment will be increasingly used in the future. Furthermore, several interventional and medical (opioids and non-opioids) approaches have been considered to target chronic and intractable pain (e.g. low back pain), with different efficacy and risks (9-17).

Surgical site infections (SSIs), which accounts for a significant portion of healthcare associated infections, are a common cause of morbidity, mortality, and increased healthcare costs (18-20). Infection rates associated with SCS vary in the literature from 1 - 10% and are relatively greater to those recorded for other implantable devices (21-23). The majority of SSIs are due to the patient’s skin flora, with Staphylococcus aureus and coagulase-negative staphylococci being the predominant bacteria. In addition, methicillin-resistant Staphylococcus aureus (MRSA) is becoming more prevalent, and increasingly more difficult to treat (22). The implantable pulse generator (IPG) site is the chief location for over 50% of infections related to SCS (22).

The Center for Disease Control and Prevention (CDC) recommends several measures to prevent surgical site infections (24). These measures include pre-operative measures, such as glycemic control, avoiding routine use of vancomycin, and intraoperative measures, including skin antisepsis, and limiting traffic within the operating room (24). The use of a prophylactic antibiotic therapy is categorized as a class IA, meaning it is strongly recommended for implementation and supported by well-designed studies (24). The Neuromodulation Appropriateness Consensus Committee (NACC) guidelines also recommend the use of pre-operative antibiotic prophylaxis as a strong and effective practice in preventing SSI, with up to 50% reduction in infections (22, 25). It is worth noting that antibiotic therapy should be tailored to the patient, such that it is weight based and appropriately formulated from the nasal swab. Without optimizing antibiotic therapy, the risk of wound infections is dramatically increased (22, 26).

In 2013, Provenzano et al. conducted a survey on perioperative infection control practices (27). The survey revealed that only 4 of 15 questions regarding infection control recommend practice had high compliance (27). The Neuromodulation Appropriateness Consensus Committee (NACC) Recommendations for Infection Prevention and Management were published in 2017 to improve patient care and reduce morbidity and mortality related to surgical site infections (22). Their recommendations include optimizing diabetes, smoking cessation, utilizing pre-procedural nasal swab testing, and weight-based antibiotics (22).

We designed a 31-item questionnaire regarding common and important topics for spinal cord stimulation to assess common practices in the neuromodulating community, including questions about antibiotic usage during trial and implant as well as screening for Staphylococcus aureus and MRSA. Given that SCS infection rates continue to be higher than other implantable devices, we have devoted this article to discuss and analyze the details pertaining to the use of antibiotics and detection of methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA colonization.

A questionnaire was developed to inquire about practices around SCS. Questions were designed by the authors based upon perceived importance, and purposefully limited to prevent the survey becoming excessively long or burdensome. It was submitted and approved by the Institutional Review Board and, subsequently, approved by the Boards of American Society of Regional Anesthesia (ASRA) and Spine Intervention Society (SIS). The survey could not be sent to a dedicated neuromodulation society because of logistic issues.

A modified questionnaire, consisting of 31 questions related to various aspects of SCS practice, was translated into the Survey Monkey, Inc., Copyright 1999 - 2021, available at https://wwww.surveymonkey.com. The questionnaire was then distributed by the ASRA and SIS to all active members by email with the web link for anonymous participation. Given many pain physicians are members of both societies, recipients were asked to complete the survey only once. The response rate was calculated based on number of members who opened the email and assuming only 20% of the recipients were truly eligible because these are multidisciplinary societies. We did not make adjustment for overlapping membership because this information is also not available. This review presents the findings of the questions pertaining to the perioperative use of antibiotics during trial and permanent implants, and nares swabbing for MSSA and MRSA.

The results for the questions regarding perioperative antibiotic use and nasal swabbing are presented below. The survey was delivered to 2967 members of SIS and 3169 members of ASRA with 1259 and 1477 members of each society opening the email. Of those which opened the email, a maximum of 195 responses were received. The survey responses were attained between 20th March 2020 and 26th June, 2020. Assuming 20% recipients were actively practicing SCS, the response rate for question 1 was 35.6%, question 2 was 33.1%, question 3 was 35.6% and question 4 was 35.5%.

There was significant heterogeneity among physicians on the use of antibiotics for the SCS procedure. As seen in Table 1, the majority of physicians use antibiotics for the trial (82.6%), with 47% using a single dose of antibiotics during the procedure and 35% using antibiotics for the duration of the trial. Approximately 17% of physicians do not administer any antibiotics during the procedure or the duration of the trial. For the use of antibiotics for the permanent implant, over 95% of pain physicians utilize antibiotics (refer to Table 2). This was further assessed by length of usage, with 44% utilizing a single dose during the procedure, 11% utilizing antibiotics for up to 24 hours, 24% utilizing antibiotics between 3 - 5 days, and 14% utilizing antibiotics for more than 5 days. A small portion of physicians, 4%, do not administer antibiotics for the permanent implant.

The use of nasal swabs prior to undertaking any SCS procedure was low. Table 3 outlines the use of nasal swabs prior SCS trial or implantation. Approximately 69% and 82% of physicians do not incorporate MRSA and MSSA nasal swabs prior the procedure.

The practice parameters for perioperative infection control vary among clinicians. The results of almost 200 practicing neuromodulation physicians presented here provide information on basic infection control practices for both SCS trials and implants. Compared to the survey by Provenzano et al, there has not been a substantial increase in the use of antibiotics among clinicians (> 80% vs > 82%) for SCS trials (27). Nonetheless, there continues to be a significant portion of physicians who do not adhere to the NACC guidelines. Our data suggest 47% and 56% of physicians utilize antibiotics for trials and implants, respectively, as a single dose or up to 24 hours, which is in compliance with NACC guidelines. Approximately 39% of providers extend antibiotic use up to more than 5 days for implants. As compared to Provenzano et al, the number of clinicians that continue antibiotics in the postoperative period has decreased to 35% from 50.5% for SCS trials and to 39% from 57% for implants (27). This decrease may reflect the NACC guidelines’ recommendation to consider discontinuing antibiotics within 24 hours for implantation (22). Indeed, infections associated with SCS are the most common complication after implantation (23). This can lead to not only explantation and infection in the epidural space, but also increased morbidity, and increased healthcare costs (23, 28). However, studies indicate prolonged antibiotic use in the post-operative period does not improve outcomes and may contribute to multidrug-resistant bacteria, including MRSA, which can lead to increased morbidity and mortality (22, 29, 30). On the other hand, 17% (34/181) of clinicians do not use antibiotics prior to performing an SCS trial and 4% (8/195) prior to an SCS implant despite evidence that the preoperative use of antibiotics, independent of surgery type, results in a 50% decrease in the incidence of wound infections (23, 25).

NACC guidelines help establish standard practices in order to improve patient safety. For the purposes of antibiotic use, they recommend pre-procedure antibiotic use and discontinuation of antibiotics within 24 hours (22). NACC guidelines endorse tailoring antibiotics to community, hospital, and resistance patterns of organisms (22). They further recommend that for most SCS procedures, a single dose of a cephalosporin, such as cefazolin, is appropriate (22). Cefazolin is favorable in terms of having a high safety profile, low cost, and activity against common organisms, such as MSSA, that cause SSIs (28, 31). In patients with a beta-lactam allergy, clindamycin or vancomycin can be considered (22). However, vancomycin should be reserved for patients with MRSA colonization, as seen on nasal swab (22, 28, 32, 33). This is important to help limit multidrug resistant infections, including vancomycin-resistant strains (34). In addition, vancomycin is less effective than cefazolin in preventing MSSA related SSIs (28, 35). The antibiotic should be administered intravenously approximately 30 - 60 minutes prior to incision, with the exception of vancomycin which should be administered 120 minutes prior to incision (22, 28).

Our results also indicate that a large percentage of clinicians (82% and 69%) are not testing for MSSA or MRSA prior to a SCS trial or implant, despite level IA evidence from the NACC guidelines to decolonize MRSA prior to the procedure (22). This underutilized diagnostic test can help identify patients who are carriers of MSSA and MRSA and is recommended by the NACC guidelines (22). Because being either a MSSA or MRSA carrier is the most important risk factor of SSIs, these patients are at a significantly higher risk of developing an infection (22, 36-39). Both MSSA and MRSA are commonly located in the anterior nares, perianal, and groin regions (22). Pre-procedure nasal swab testing for both MSSA and MRSA, allows for the detection of these bacteria to not only signify when to decolonize the patient, but to administer appropriate antibiotics, such as vancomycin. Decolonization entails application of mupirocin nasal ointment and chlorhexidine wash prior the procedure (22). About to 1/3 of the population are carriers of S. aureus, illustrating that nasal swabs are cost effective manner to identify a large portion of patients who are at higher risk of infection (22, 40). Despite this, nasal screening may not detect up to 20% of patients with colonization (41). On the other hand, it is not clear if universal decolonization may be beneficial (41). Decolonization with mupirocin may also lead to mupirocin resistance S. aureus, which can potentially cause failure of decolonization (41). More information is needed to determine optimization of decolonization.

There continue to be obstacles in which ongoing education and NACC guidelines are not implemented by physicians. The duration of antibiotic use in SCS and nasal swab testing vary widely among practicing physicians. Provenzano et al published in 2013, and nearly 7 years later, our results remain comparable (27). The barriers to adoption of best antibiotic prophylaxis measures may include lack of accessibility of information and consensus guidelines, ongoing education regarding guidelines, and physicians' adherence to their routine practices.