Infection following operations on the central nervous system: deconstructing the myth of the sterile field

Main Operating Room Versus Field Sterility in Hand Surgery: A Review of the Evidence

Introduction: Many of the guidelines that are generally accepted as main operating room best practices are not evidence based. They are based on the concept that if some sterility is good, more must be better. They are not derived from evidence-based sterility. Evidence-based sterility is the study of which of our various sterility practices increase or decrease our infection rates, as opposed to guidelines based on how many bacteria are in the operating room. Methods: This article adds the most important evidence we could find that is not included in the first paper on evidence-based sterility in hand surgery published in 2019. In this review, we also balance the evidence with common sense opinion. Results: The 21st century has seen a rapid rise in the number and reports of hand surgery procedures performed with field sterility outside the main operating room. There is now an abundance of good evidence to support that the rate of infection is not higher when many hand operations are performed with field sterility in minor procedure rooms. Conclusion: Moving hand surgery out of the main operating room to minor procedure rooms should be supported by healthcare providers. The higher cost, increased solid waste, and inconvenience of main operating room surgery are not justifiable for many procedures because it does not reduce the risk of postoperative infection.

Risk Factors for Central Nervous System Infections After Craniotomy

The central nervous system (CNS) is less prone to infection owing to protection from the brain-blood barrier. However, craniotomy destroys this protection and increases the risk of infection in the brain of patients who have undergone craniotomy. CNS infection after craniotomy significantly increases the patient's mortality rate and disability. Controlling the occurrence of intracranial infection is very important for post-craniotomy patients. CNS infection after craniotomy is caused by several factors such as preoperative, intraoperative, and post-operative factors. Craniotomy may lead to postsurgical intracranial infection, which is mainly associated with surgery duration, infratentorial (posterior fossa) surgery, cerebrospinal fluid leakage, drainage tube placement, unregulated use of antibiotics, glucocorticoid use, age, diabetes, and other systemic infections. Understanding the risk factors of CNS infection after craniotomy can benefit reducing the incidence of intracranial infectious diseases. This will also provide the necessary guidance and evidence in clinical practice for planning to control intracranial infection in patients with craniotomy.

Incidence and Risk Factors of Surgical Site Infection After Cranial Surgery for Patients with Brain Tumors: A Systematic Review and Meta-analysis

BACKGROUND

Surgical site infections after craniotomy (SSI-CRANs) are a serious adverse event given the proximity of the wound to the central nervous system. SSI-CRANs are associated with substantial patient morbidity and mortality. Despite the importance and recognition of this event in other surgical fields, there is a paucity of evidence in the neurosurgical literature devoted to SSI-CRAN specifically in patients after brain tumor surgery.

METHODS

Systematic searches of Medline, Embase, and Cochrane Central were undertaken. The primary outcome was the incidence of SSI-CRAN at 30 and 90 days. Secondary outcomes were risk factors for SSI-CRAN.

RESULTS

Thirty-seven studies reporting 91,907 patients with brain tumors who underwent cranial surgery were included in the meta-analysis. Pooled incidence of SSI-CRAN at 30 and 90 days was 4.03% (95% CI: 2.94%-5.28%, I2 = 97.3) and 6.17% (95% CI: 3.16%-10.07%, I2 = 97.3), respectively. Specifically, incidence of SSI-CRAN following surgery for posterior fossa tumors was the highest at 9.67% (95% CI: 5.98%-14.09%, I2 = 75.5). Overall pooled incidence of readmission within 30 days and reoperation due to SSI-CRAN were 13.9% (95% CI: 12.5%-15.5%, I2 = 0.0) and 16.3% (95% CI: 5.4%-31.3%, I2 = 72.9), respectively. Risk factors for SSI-CRAN included reintervention (risk ratio [RR] 1.58, 95% CI: 1.22-2.04, I2 = 0.0), previous radiotherapy (RR 1.69, 95% CI: 1.20-2.38, I2 = 0.0), longer duration of operation (mean difference 64.18, 95% CI: 3.96-124.40 minutes, I2 = 90.3) and cerebrospinal fluid (CSF) leaks (RR 14.26, 95% CI: 2.14-94.90, I2 = 73.2).

CONCLUSIONS

SSI-CRAN affects up to 1 in 14 patients with brain tumors. High-risk groups include those with reintervention, previous radiotherapy, longer duration of operation, and CSF leaks. Further prospective studies should focus on bundles of care that will reduce SSI-CRAN.

Predictors of Surgical Site Infection After Nonemergent Craniotomy: A Nationwide Readmission Database Analysis

OBJECTIVE

Surgical site infections (SSIs) carry significant patient morbidity and mortality and are a major source of readmissions after craniotomy. Because of their deleterious effects on health care outcomes and costs, identifying modifiable risk factors holds tremendous value. However, because SSIs after craniotomy are rare and most existing data comprise single-institution studies with small sample sizes, many are likely underpowered to discern for such factors. The objective of this study was to use a large hetereogenous patient sample to determine SSI incidence after nonemergent craniotomy and identify factors associated with readmission and subsequent need for wound washout.

METHODS

We used the 2010-2014 Nationwide Readmissions Database cohorts to discern for factors predictive of SSI and washout.

RESULTS

We identified 93,920 nonemergent craniotomies. There were 2079 cases of SSI (2.2%) and 835 reoperations for washout (0.89%) within 30 days of index admission and there were 2761 cases of SSI (3.6%) and 1220 reoperations for washout (1.58%) within 90 days. Several factors were predictive of SSI in multivariate analysis, including tumor operations, external ventricular drain (EVD), age, length of stay, diabetes, discharge to an intermediate-care facility, insurance type, and hospital bed size. Many of these factors were similarly implicated in reoperation for washout.

CONCLUSIONS

SSI incidence in neurosurgery is low and most readmissions occur within 30 days. Several factors predicted SSI after craniotomy, including operations for tumor, younger age, hospitalization length, diabetes, discharge to institutional care, larger hospital bed size, Medicaid insurance, and presence of an EVD. Diabetes and EVD placement may represent modifiable factors that could be explored in subsequent prospective studies for their associations with cranial SSIs.

Complications and 30-Day readmission rates after craniotomy/craniectomy: A single Institutional study of 243 consecutive patients

Early hospital readmission has become a proxy for quality of care and contributes significantly to high health care costs in the United States, with more than $20 billion health care dollars are spent on 30-day readmission annually. Cranial neurosurgical procedures (i.e., craniotomy, craniectomy) are associated with high readmission rates; however, studies examining readmission after cranial procedures are limited and relatively unknown. The aim of this study is to identify the drivers of 30-day unplanned readmission in consecutive patients undergoing craniotomies and craniectomies. The medical records of 243 consecutive patients undergoing either craniotomy or craniectomy at a major academic institution in 2011 were reviewed. Patient demographics, comorbidities, intra- and post-operative complication rates were collected for each patient. We identified all unplanned readmissions within 30 days of discharge. A total of 10 (4.1%) unplanned 30-day readmissions were identified. The mean ± SD age was 58.58 ± 15.12 years. The most common indication for surgery was malignancy (63.4%) followed by Chiari malformation (10.3%), epilepsy (5.3%), and skull lesion/deformity (2.9%). The majority of patients presented to the emergency department from home (80%), while 10% were readmitted from a skilled nursing facility and 10% were readmitted from an acute rehabilitation institution. The most common presented symptoms for readmitted patients were fever/presumed infection (40%) and altered mental status (40%), followed by new sensory/motor deficits (30%). This study suggests that infection, altered mental status, and new sensory/motor deficits were the primary complications leading to unplanned 30-day readmission after cranial neurosurgery.

Efficacy of vancomycin-releasing biodegradable poly(lactide-co-glycolide) antibiotics beads for treatment of experimental bone infection due to Staphylococcus aureus

BACKGROUND

Clinical experience and animal studies have suggested that positron emission tomography (PET) using fluorine-18-labeled fluorodeoxyglucose ((18)F-FDG) may be promising for imaging of bone infections. In this study, we aimed to establish the accuracy of (18)F-FDG PET scanning for monitoring the response to poly(lactide-co-glycolide) (PLGA) vancomycin beads for treatment of bone infection.

METHODS

PLGA was mixed with vancomycin and hot-compress molded to form antibiotic beads. In vitro, elution assays and bacterial inhibition tests were employed to characterize the released antibiotics. In vivo, cylindrical cavities were made in six adult male New Zealand white rabbits, and Staphylococcus aureus or saline was injected into the cavity to create a bone infection. After 2 weeks, the infection was confirmed by bacterial cultures, and the defect was filled with PLGA vancomycin beads. The treatment response was monitored by (18)F-FDG PET.

RESULTS

The biodegradable beads released high concentrations of vancomycin (well above the breakpoint sensitivity concentration) for treatment of bone infection. In bacterial inhibition tests, the diameter of the sample inhibition zone ranged from 6.5 to 10 mm, which was equivalent to 12.5-100 % relative activity. (18)F-FDG PET results showed that uncomplicated bone healing was associated with a temporary increase in (18)F-FDG uptake at 2 weeks, with return to near baseline at 6 weeks. In the infected animals, localized infection resulted in intense continuous uptake of (18)F-FDG, which was higher than that in uncomplicated healing bones. Bone infection was confirmed with positive bacterial cultures. In vancomycin-treated animals, data showed rapidly decreasing amounts of (18)F-FDG uptake after treatment.

CONCLUSIONS

In vitro and in vivo analyses showed that the use of biodegradable PLGA vancomycin beads successfully eradicated S. aureus infection in damaged bone.

Post-operative shampoo effects in neurosurgical patients: a pilot experimental study

BACKGROUND

Neurosurgical site infections are an important issue. Among the acknowledged preventive tactics, the non-shaving technique is well established in the neurosurgical setting. However, given that patient's hair around the surgical site may retain biologic material that emerges during the surgical procedure or that may simply become dirty, which may increase the risk of surgical site infections, if and when shampooing should be offered remains under debate.

METHODS

A pilot experimental study was undertaken from 2011 to 2012. A series of neurosurgical patients not affected by conditions that would increase the risk of post-operative infection were assigned randomly to the exposed group (receiving shampoo 72 h after surgical procedure) or control group (receiving standard dressing surveillance without shampooing). Comfort, surgical site contamination (measured as the number of colony-forming units [CFU]), and SSIs at 30 d after surgery were the main study outcomes.

RESULTS

A total of 53 patients were included: 25 (47.2%) received a shampoo after 72 h whereas 28 (52.8%) received standard care. Patients who received a shampoo reported a similar level of comfort (average=8.04; standard deviation [SD] 1.05) compared with those receiving standard care (average 7.3; SD 3.2) although this was not statistically significant (p=0.345). No statistically significant difference emerged in the occurrence of surgical site contamination between the groups, and no SSIs were detected within 30 d.

CONCLUSIONS

In our pilot study, the results of which are not generalizable because of the limited sample of patients involved, a gentle shampoo offered 72 h after the surgical procedure did not increase the SSIs occurrence or the contamination of the surgical site, although it may increase the perception of comfort by patients. Further studies are strongly recommended involving a larger sample size and designed to include more diversified neurosurgical patients undergoing surgical procedures in different centers.

Biodegradable vancomycin-eluting poly[(d,l)-lactide-co-glycolide] nanofibres for the treatment of postoperative central nervous system infection

The incidence of postoperative central nervous system infection (PCNSI) is higher than 5%–7%. Successful management of PCNSI requires a combined therapy of surgical debridement and long-term antibiotic treatment. In this study, Duraform soaked in a prepared bacterial solution was placed on the brain surface of rats to induce PCNSI. Virgin poly[(d,l)-lactide-co-glycolide] (PLGA) nanofibrous membranes (vehicle-control group) and vancomycin-eluting PLGA membranes (vancomycin-nanofibres group) were implanted. The wound conditions were observed and serial brain MRI and pathology examinations were performed regularly. PCNSI was consistently induced in a single, simple step. In the vehicle-control group, most rats died within 1 week, and the survival rate was low (odds ratio = 0.0357, 95% confidence interval = 0.0057–0.2254). The wounds and affected cerebral tissues necrosed with purulence and increased in mass from the resulting PCNSI volumes. Initially, the mean PCNSI volumes showed no significant difference between the two groups. The PCNSI volume in the rats in the vancomycin-nanofibres group significantly decreased (P < 0.01), and the wound appearance was excellent. Pathologic examinations revealed that the necrosis and leukocyte infiltration area decreased considerably. The experimental results suggest that vancomycin-eluting PLGA nanofibres are favourable candidates for treating PCNSI after surgical debridement.

Current Microbiology of Surgical Site Infections in Patients with Cancer: A Retrospective Review

Background

Patients with solid tumors frequently undergo surgical procedures and develop procedure-related infections. We sought to describe the current microbiologic spectrum of infections at various sites following common surgical procedures.

Methods

This was a retrospective review of microbiologic data between January 2011 and February 2012. The sites studied were those associated with breast cancer surgery, thoracotomy, craniotomy, percutaneous endoscopic gastrostomy (PEG) tube insertion, and abdominal/pelvic surgery. Only patients with solid tumors were included.

Results

A total of 368 surgical site infections (SSIs) were identified (68 breast cancer related; 91 thoracotomy related; 45 craniotomy related; 75 PEG-tube insertion related; and 89 abdominal/pelvic surgery related). Of these, 58% were monomicrobial and 42% were polymicrobial. Overall, 85% of the 215 monomicrobial infections were caused by Gram-positive organisms and 13% by Gram-negative bacilli (GNB). Staphylococcus aureus was the predominant pathogen in monomicrobial infections (150 of 215, 70%). Sixty (40%) of these staphylococcal isolates were methicillin resistant (MRSA), and 65% had a vancomycin minimal inhibitory concentration (MIC) ≥1.0 µg/ml. Pseudomonas aeruginosa was the predominant GNB pathogen (19 of 27, 70%). Staphylococci were also the predominant pathogens in polymicrobial infections, while P. aeruginosa and Escherichia coli were the predominant GNB. Overall, 35% of isolates from polymicrobial infections were GNB. Cephalosporins (e.g., cefazolin) or amoxicillin/clavulanate was used most often for surgical prophylaxis, and 47% of organisms from monomicrobial infections (MRSA, P. aeruginosa) were resistant to them. A similar resistance pattern was observed in polymicrobial infections.

Conclusion

Staphylococcus species were isolated most often from the sites studied. Polymicrobial infections (42%) and GNB monomicrobial infections (13%) were relatively frequent causes of SSIs. Many of these infections were caused by organisms that are resistant to agents commonly used for surgical prophylaxis. Additionally, 65% of staphylococcal isolates had a vancomycin MIC ≥1.0 µg/ml, suggesting the need for alternative therapeutic agents.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0048-4) contains supplementary material, which is available to authorized users.

Restoration of vision in blind individuals using bionic devices: a review with a focus on cortical visual prostheses

The field of neurobionics offers hope to patients with sensory and motor impairment. Blindness is a common cause of major sensory loss, with an estimated 39 million people worldwide suffering from total blindness in 2010. Potential treatment options include bionic devices employing electrical stimulation of the visual pathways. Retinal stimulation can restore limited visual perception to patients with retinitis pigmentosa, however loss of retinal ganglion cells precludes this approach. The optic nerve, lateral geniculate nucleus and visual cortex provide alternative stimulation targets, with several research groups actively pursuing a cortically-based device capable of driving several hundred stimulating electrodes. While great progress has been made since the earliest works of Brindley and Dobelle in the 1960s and 1970s, significant clinical, surgical, psychophysical, neurophysiological, and engineering challenges remain to be overcome before a commercially-available cortical implant will be realized. Selection of candidate implant recipients will require assessment of their general, psychological and mental health, and likely responses to visual cortex stimulation. Implant functionality, longevity and safety may be enhanced by careful electrode insertion, optimization of electrical stimulation parameters and modification of immune responses to minimize or prevent the host response to the implanted electrodes. Psychophysical assessment will include mapping the positions of potentially several hundred phosphenes, which may require repetition if electrode performance deteriorates over time. Therefore, techniques for rapid psychophysical assessment are required, as are methods for objectively assessing the quality of life improvements obtained from the implant. These measures must take into account individual differences in image processing, phosphene distribution and rehabilitation programs that may be required to optimize implant functionality. In this review, we detail these and other challenges facing developers of cortical visual prostheses in addition to briefly outlining the epidemiology of blindness, and the history of cortical electrical stimulation in the context of visual prosthetics.

Infections in patients undergoing craniotomy: risk factors associated with post-craniotomy meningitis

OBJECT The authors performed a prospective study to define the prevalence and microbiological characteristics of infections in patients undergoing craniotomy and to clarify the risk factors for post-craniotomy meningitis. METHODS Patients older than 18 years who underwent nonstereotactic craniotomies between January 2006 and December 2008 were included. Demographic, clinical, laboratory, and microbiological data were systemically recorded. Patient characteristics, craniotomy type, and pre- and postoperative variables were evaluated as risk factors for meningitis RESULTS Three hundred thirty-four procedures were analyzed (65.6% involving male patients). Traumatic brain injury was the most common reason for craniotomy. Almost 40% of the patients developed at least 1 infection. Ventilator-associated pneumonia (VAP) was the most common infection recorded (22.5%) and Acinetobacter spp. were isolated in 44% of the cases. Meningitis was encountered in 16 procedures (4.8%), and CSF cultures were positive for microbial growth in 100% of these cases. Gram-negative pathogens (Acinetobacter spp., Klebsiella spp., Pseudomonas aeruginosa, Enterobacter cloaceae, Proteus mirabilis) represented 88% of the pathogens. Acinetobacter and Klebsiella spp. demonstrated a high percentage of resistance in several antibiotic classes. In multivariate analysis, the risk for meningitis was independently associated with perioperative steroid use (OR 11.55, p = 0.005), CSF leak (OR 48.03, p < 0.001), and ventricular drainage (OR 70.52, p < 0.001). CONCLUSIONS Device-related postoperative communication between the CSF and the environment, CSF leak, and perioperative steroid use were defined as risk factors for meningitis in this study. Ventilator-associated pneumonia was the most common infection overall. The offending pathogens presented a high level of resistance to several antibiotics.

The incidence of complications in elective cranial neurosurgery associated with dural closure material

OBJECT

Dural closure with synthetic grafts has been suggested to contribute to the incidence of infection and CSF leak. The objective of this study was to assess the contribution of choice of dural closure material, as well as other factors, to the incidence of infection and CSF leak.

METHODS

A retrospective, consecutive cohort study of adult patients undergoing elective craniotomy was established between April 2010 and March 2011 at a single center. Exclusion criteria consisted of trauma, bur hole placement alone, and temporary CSF fluid diversion.

RESULTS

Three hundred ninety-nine patients were included (mean follow-up 396.6 days). Nonautologous (synthetic) dural substitute was more likely to be used (n = 106) in cases of reoperation (p = 0.001). Seventeen patients developed a surgical site infection and 12 patients developed a CSF leak. Multivariate logistic regression modeling identified estimated blood loss (OR 1.002, 95% CI 1.001-1.003; p < 0.001) and cigarette smoking (OR 2.198, 95% CI 1.109-4.238; p = 0.019) as significant predictors of infection. Synthetic dural graft was not a predictor of infection in multivariate analysis. Infratentorial surgery (OR 4.348, 95% CI 1.234-16.722; p = 0.024) and more than 8 days of postoperative corticosteroid treatment (OR 3.886, 95% CI 1.052-16.607; p = 0.048) were significant predictors for the development of CSF leak. Synthetic dural graft was associated with a lower likelihood of CSF leak (OR 0.072, 95% CI 0.003-0.552; p = 0.036).

CONCLUSIONS

The use of synthetic dural closure material is not associated with surgical site infection and is associated with a reduced incidence of CSF leak. Modifiable risk factors exist for craniotomy complications that warrant vigilance and further study.