Protective effect of rifampicin and clindamycin impregnated devices against Staphylococcus spp. infection after cerebrospinal fluid diversion procedures

Efficacy of Lysostaphin functionalized silicon catheter for the prevention of Staphylococcus aureus biofilm

Staphylococcus aureus readily forms biofilms on tissue and indwelling catheter surfaces. These biofilms are resistant to antibiotics. Consequently, effective prevention and treatment strategies against staphylococcal biofilms are actively being pursued over the past two decades. One of the proposed strategies involve the incorporation of antibiotics and antiseptics into catheters, however, a persistent concern regarding the possible emergence of antimicrobial resistance is associated with these medical devices. In this study, we developed two types of silicone catheters: one with Lysostaphin (Lst) adsorbed onto the surface, and the other with Lst functionalized on the surface. To confirm the presence of Lst protein on the catheter surface, we conducted FTIR-ATR and SEM-EDS analysis. Both catheters exhibited hemocompatibility, biocompatibility, and demonstrated antimicrobial and biofilm prevention activities against both methicillin-sensitive and resistant strains of S. aureus. Furthermore, the silicone catheters that were surface-functionalized with Lst showed substantially better and more persistent anti-biofilm effects when compared to the catheters where Lst was surface-adsorbed, both under in vitro static and flow conditions, as well as in vivo in BALB/c mice. These results indicate that surface-functionalized Lst catheters have the potential to serve as a promising new medical device for preventing S. aureus biofilm infections in humans.

Risk Factors for External Ventricular Drainage-Related Infection: A Systematic Review and Meta-analysis

Background and Objectives

External ventricular drainage (EVD) is one of the most commonly performed neurosurgical procedures, but EVD-related infection constitutes a significant health concern. Yet, little consensus identifies the risk factors for the development of EVD-related infection. Therefore, we performed a meta-analysis to systematically summarize existing evidence on the incidence and risk factors for EVD-related infection.

Methods

PubMed, Embase, and the Cochrane Library databases from database inception to February 28, 2022, were searched for all studies investigating the incidence and risk factors for EVD-related infection. Data were assessed by R-4.2.0 software. The meta-analysis was used to calculate pooled odds ratios (OR) and 95% confidence intervals (CI).

Results

A total of 48 studies were included. Among the 29 factors analyzed, statistically significant risk factors were subarachnoid hemorrhage(SAH)/intraventricular hemorrhage(IVH) (OR = 1.48, 95% CI = 1.20-1.82, p < 0.001), concomitant systemic infection (OR = 1.90, 95% CI = 1.34-2.70, p < 0.001), other neurosurgical procedures (OR = 1.76, 95% CI = 1.02-3.04, p = 0.041), change of catheter (OR = 5.05, 95% CI = 3.67-6.96, p < 0.001), bilateral EVDs (OR = 2.25, 95% CI = 1.03-4.89, p = 0.041), (cerebrospinal fluid) CSF leak (OR = 3.19, 95% CI = 2.12-4.81, p < 0.001) and duration of EVD >7 days (OR = 4.62, 95% CI = 2.26-9.43, p < 0.001). The use of silver-coated catheters (OR = 0.57, 95% CI = 0.38-0.87, p = 0.008) and antibiotic-impregnated catheters (OR = 0.60, 95% CI = 0.41-0.88, p = 0.009) might help reduce the risk of infection. No significant difference was indicated in studies evaluating factors like diabetes mellitus (OR = 1.25, 95% CI = 0.90-1.75, p = 0.178), steroids used (OR = 1.52, 95% CI = 0.96-2.4, p = 0.074), prophylactic antibiotics(OR = 0.87, 95% CI = 0.66-1.14, p = 0.308).

Discussion

The meta-analysis of various relevant factors in the onset of EVD-related infection in patients submitted to EVD enabled us to establish a more probable profile of the patients who are more likely to develop it during the treatment.

Systematic Review and Meta-Analysis of Antibiotic-Impregnated Shunt Catheters on Anti-Infective Effect of Hydrocephalus Shunt

OBJECTIVE

Shunt infection is a common complication while treating hydrocephalus. The antibiotic-impregnated shunt catheter (AISC) was designed to reduce shunt infection rate. A meta-analysis was conducted to study the effectiveness of AISCs in reduction of shunt infection in terms of age, follow-up time and high-risk patient population.

METHODS

This study reviewed literature from three databases including PubMed, EMBASE, and Cochrane Library (from 2000 to March 2019). Clinical studies from controlled trials for shunt operation were included in this analysis. A subgroup analysis was performed based on the patient's age, follow-up time and high-risk population. The fixed effect in RevMan 5.3 software (Cochrane Collaboration) was used for this meta-analysis.

RESULTS

This study included 19 controlled clinical trials including 10105 operations. The analysis demonstrated that AISC could reduce the infection rate in shunt surgery compared to standard shunt catheter (non-AISC) from 8.13% to 4.09% (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.40-0.58; p=0.01; I2=46%). Subgroup analysis of different age groups showed that AISC had significant antimicrobial effects in all three groups (adult, infant, and adolescent). Follow-up time analysis showed that AISC was effective in preventing early shunt infections (within 6 months after implant). AISC is more effective in high-risk population (OR, 0.24; 95% CI, 0.14-0.40; p=0.60; I2=0%) than in general patient population.

CONCLUSION

The results of meta-analysis indicated that AISC is an effective method for reducing shunt infection. We recommend that AISC should be considered for use in infants and high-risk groups. For adult patients, the choice for AISC could be determined based on the treatment cost.

Systemic Antimicrobial Prophylaxis and Antimicrobial-Coated External Ventricular Drain Catheters for Preventing Ventriculostomy-Related Infections: A Meta-Analysis of 5242 Cases

BACKGROUND

External ventricular drain (EVD) placement is essential for the management of many neurocritical care patients. However, ventriculostomy-related infection (VRI) is a serious complication, and there remains no well-established protocol guiding use of perioperative or extended antibiotic prophylaxis to minimize risk of VRI.

OBJECTIVE

To analyze published evidence on the efficacy of extended prophylactic antimicrobial therapy and antibiotic-coated external ventricular drains (ac-EVDs) in reducing VRI incidence.

METHODS

We searched PubMed for studies related to VRIs and antimicrobial prophylaxis. Eligible articles reported VRI incidence in control and treatment cohorts evaluating prophylaxis with either extended systemic antibiotics (> 24 hr) or ac-EVD. Risk ratios and VRI incidence were aggregated by prophylactic strategy, and pooled estimates were determined via random or mixed effects models. Study heterogeneity was quantified using I2 and Cochran's Q statistics. Rigorous assessment of study bias was performed, and PRISMA guidelines were followed throughout.

RESULTS

Across 604 articles, 19 studies (3%) met eligibility criteria, reporting 5242 ventriculostomy outcomes. Extended IV and ac-EVD prophylaxis were associated with risk ratios of 0.36 [0.14, 0.93] and 0.39 [0.21, 0.73], respectively. Mixed effects analysis yielded expected VRI incidence of 13% to 38% with no prophylaxis, 7% to 18% with perioperative IV prophylaxis, 3% to 9% with either extended IV or ac-EVD prophylaxis as monotherapies, and as low as 0.8% to 2% with extended IV and ac-EVD dual prophylaxis.

CONCLUSION

Management with both extended systemic antibiotics and ac-EVDs could lower VRI risk in ventriculostomy patients, but the impact on associated morbidity and mortality, healthcare costs, and length of stay remain unclear.

Infection Prevention in the Neurointensive Care Unit: A Systematic Review

Hospital-acquired infections are common in neurointensive care units. We sought to review interventions which may reduce infection rates in neurocritically ill populations. We conducted a systematic review of studies targeting adult patients in neuro-intensive care units (neuro-ICUs) with an intervention designed to prevent ICU-acquired infections. Our outcome of interest was change in the prevalence or rates of infection between active and control arms of these studies. We excluded studies based on the following criteria: no English full-text version available; pediatric population; non-neurosciences ICU population; pre- or intraoperative methods to prevent infection; lack of discrete data for infection rates/prevalence; studies that were purely observational in nature and did not test an intervention; and studies performed in resource limited settings. We initially retrieved 3716 results by searching the following databases: PubMed/MEDLINE, EMBASE via Ovid, and Cochrane CENTRAL via Ovid. No date or language limits were used in the search. Computerized deduplication was conducted using EndNote followed by a confirmatory manual review resulting in 3414 citations. An additional 19 manuscripts were identified through review of references. The screening process followed a standard protocol, using two screeners at the title/abstract level to determine relevance and at the full-text level to determine eligibility for inclusion. The 3427 titles/abstracts were independently screened by two board-certified neurointensivists to determine relevance for full-text review, and 3248 were rejected. The remaining 179 abstracts were reviewed in full text using predetermined inclusion/exclusion criteria. Ultimately, 75 articles met our inclusion criteria and were utilized in the final analysis. The reviewed literature highlights the need for collaborative, multi-disciplinary, and multi-pronged approaches to reduce infections. Rates of VRI, SSI, VAP, CAUTI, and CLABSI can approach zero with persistence and a team-based approach.

Impact of antibiotic- and silver-impregnated external ventricular drains on the risk of infections: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

External ventricular drainage (EVD) is one of the most common and effective procedures in neurosurgery practice. However, catheter-related infection (CRI), which is associated with significant mortality and morbidity, plagues this procedure. We evaluated the efficacy of antibiotic-impregnated EVD (AI-EVD) and silver-impregnated EVD (SI-EVD) catheters compared with plain EVD catheters for the prevention of CRI.

METHODS

The authors performed an independent search of Medline, Embase, and the Cochrane Library to identify eligible studies published between January 2002 and August 2014. We searched all relevant literature using an exhaustive search strategy. Randomized controlled trials or observational studies that compared AI-EVD catheters with plain EVD catheters for the prevention of CRI were included. The quality of each included study was assessed using a risk of bias assessment tool and the Newcastle-Ottawa Scale. RevMan5.3 software (The Cochrane Collaboration, Oxford, UK) was used to perform this meta-analysis, and publication bias was investigated using funnel plot constructions and Egger test.

RESULTS

A total of 4 randomized and 10 observational studies involving 4,399 patients were included in this meta-analysis. Pooled results comparing AI-EVD catheters with plain EVD catheters in the management of patients with acute high intracranial pressure demonstrated the superiority of antimicrobial EVDs for the prevention of CRI with a risk induction of 62% (95% confidence interval [CI], 0.25-0.58; P < .00001). Subgroup analyses of pooled data from separate analyses of AI-EVDs and SI-EVDs showed the efficacy of both measures for CRI prevention, with a risk ratio (RR) of 0.31 (95% CI, 0.18-0.55; P < .0001) and an RR of 0.59 (95% CI, 0.40-0.88; P = .010), respectively. The protective effects of these AI-EVD catheters remained significant in the subgroup of randomized controlled trials with an RR of 0.48 (95% CI, 0.25-0.90; P = .02). A similar result was also seen after a pooled analysis of observational studies with an RR of 0.35 (95% CI, 0.21-0.60; P = .0001). The heterogeneity among studies was moderate (I(2) = 49%) and was primarily attributed to the inclusion of 1 large, positive cohort study. Publication bias was unlikely in the current meta-analysis.

CONCLUSIONS

Our restults indicate that both AI-EVDs and SI-EVDs are more effective than plain EVDs for the prevention of CRI. There is no conclusive evidence on the preference of AI-EVDs vs SI-EVDs because of insufficient data. Further well-designed, multicenter randomized controlled trials are required to confirm the findings of this meta-analysis.

Antibiotic-impregnated catheters reduce ventriculoperitoneal shunt infection rate in high-risk newborns and infants

PURPOSE

The incidence of ventriculoperitoneal (VP) shunt infection accounts for about 5-15%, but it can rise up to 70% in specific high-risk subgroups. Antibiotic-impregnated catheters (AICs) have been designed to reduce shunt infections, but reports on their efficacy are discordant, especially in young children. The aim of this study is to assess, for the first time, the efficacy of AICs in newborns and infants at very high risk for shunt infection.

METHODS

We reviewed the medical records of newborns and infants treated with a VP shunt for newly diagnosed hydrocephalus. Patients were divided in two groups: Group A was composed by children who received AICs, whereas Group B included children implanted with standard silicone catheters (non-AICs). We compared the shunt infection rate in both groups, and analyzed differences in specific high-risk subgroups (preterm newborns, children with posthemorrhagic or postinfective hydrocephalus, and children with a previous external ventricular drainage).

RESULTS

Forty eight children younger than 1 year old were included in our study. Twenty two patients were implanted with an AIC, whereas 26 patients received a standard silicone catheter. The follow-up was at least 1 year (mean 8 ± 3 years). The overall infection rate decreased from 34% in non-AIC group to 9 % in the AIC group. Moreover, AICs showed to have a protective effect against shunt infections in all the specific high-risk subgroups analyzed.

CONCLUSIONS

This study demonstrates for the first time that AICs are effective in reducing VP shunt infection in high-risk pediatric patients younger than 1 year old.

Antimicrobial-impregnated and -coated shunt catheters for prevention of infections in patients with hydrocephalus: a systematic review and meta-analysis

OBJECT The aim of this study was to evaluate the effectiveness of antimicrobial-impregnated and -coated shunt catheters (antimicrobial catheters) in reducing the risk of infection in patients undergoing CSF shunting or ventricular drainage. METHODS The PubMed and Scopus databases were searched. Catheter implantation was classified as either shunting (mainly ventriculoperitoneal shunting) or ventricular drainage (mainly external [EVD]). Studies evaluating antibioticimpregnated catheters (AICs), silver-coated catheters (SCCs), and hydrogel-coated catheters (HCCs) were included. A random effects model meta-analysis was performed. RESULTS Thirty-six studies (7 randomized and 29 nonrandomized, 16,796 procedures) were included. The majority of data derive from studies on the effectiveness of AICs, followed by studies on the effectiveness of SCCs. Statistical heterogeneity was observed in several analyses. Antimicrobial shunt catheters (AICs, SCCs) were associated with lower risk for CSF catheter-associated infections than conventional catheters (CCs) (RR 0.44, 95% CI 0.35-0.56). Fewer infections developed in the patients treated with antimicrobial catheters regardless of randomization, number of participating centers, funding, shunting or ventricular drainage, definition of infections, de novo implantation, and rate of infections in the study. There was no difference regarding gram-positive bacteria, all staphylococci, coagulase-negative streptococci, and Staphylococcus aureus, when analyzed separately. On the contrary, the risk for methicillin-resistant S. aureus (MRSA, RR 2.64, 95% CI 1.26-5.51), nonstaphylococcal (RR 1.75, 95% CI 1.22-2.52), and gram-negative bacterial (RR 2.13, 95% CI 1.33-3.43) infections increased with antimicrobial shunt catheters. CONCLUSIONS Based on data mainly from nonrandomized studies, AICs and SCCs reduce the risk for infection in patients undergoing CSF shunting. Future studies should evaluate the higher risk for MRSA and gram-negative infections. Additional trials are needed to investigate the comparative effectiveness of the different types of antimicrobial catheters.

Cost-consequence analysis of antibiotic-impregnated shunts and external ventricular drains in hydrocephalus

OBJECT

Despite multiple preventive strategies for reducing infection, up to 15% of patients with shunt catheters and 27% of patients with external ventricular drains (EVDs) may develop an infection. There are few data on the cost-effectiveness of measures to prevent hydrocephalus catheter infection from the hospital perspective. The objective of this study was to perform a cost-consequence analysis to assess the potential clinical and economic value of antibiotic-impregnated catheter (AIC) shunts and EVDs compared with non-AIC shunts and EVDs in the treatment of hydrocephalus from a hospital perspective.

METHODS

The authors used decision analytical techniques to assess the clinical and economic consequences of using antibiotic-impregnated shunts and EVDs from a hospital perspective. Model inputs were derived from the published, peer-reviewed literature. Clinical studies comparing infection rates and the clinical and economic impact of infections associated with the use of AICs and standard catheters (non-AICs) were evaluated. Outcomes assessed included infections, deaths due to infection, surgeries due to infection, and cost associated with shunt- and EVD-related infection. A subanalysis using only AIC shunt and EVD Level I evidence (randomized controlled trial results) was conducted as an alternate to the cumulative analysis of all of the AIC versus non-AIC studies (13 of the 14 shunt studies and 4 of the 6 EVD studies identified were observational). Sensitivity analyses were conducted to determine how changes in the values of uncertain parameters affected the results of the model.

RESULTS

In 100 patients requiring shunts, AICs may be associated with 0.5 fewer deaths, 71 fewer hospital days, 11 fewer surgeries, and $128,228 of net savings in hospital costs due to decreased infection. Results of the subanalysis showed that AICs may be associated with 1.9 fewer deaths, 1611 fewer hospital days, 25 fewer surgeries, and $346,616 of net savings in hospital costs due to decreased infection. The rate of decrease in infection with AIC shunts was shown to have the greatest impact on the cost savings realized with use of AIC shunts.

In 100 patients requiring EVDs, AICs may be associated with 2.7 fewer deaths and 82 fewer hospital days due to infection. The relative risk of more severe neurological impairment was estimated to be 5.33 times greater with EVD infection. Decreases in infection with AIC EVDs resulted in an estimated $264,069 of net savings per 100 patients treated with AICs. Results of the subanalysis showed that AIC EVDs may be associated with 1.0 fewer deaths, 31 infection-related hospital days averted, and $74,631 saved per 100 patients treated with AIC EVDs. As was seen with AIC shunts, the rate of decrease in infection with AIC EVDs was shown to have the greatest impact on the cost savings realized with use of AIC EVDs.

CONCLUSIONS

The current value analysis demonstrates that evidence supports the use of AICs as effective and potentially cost-saving treatment.

Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 7: Antibiotic-impregnated shunt systems versus conventional shunts in children: a systematic review and meta-analysis

OBJECT

The objective of this systematic review and meta-analysis was to answer the following question: Are antibiotic-impregnated shunts (AISs) superior to standard shunts (SSs) at reducing the risk of shunt infection in pediatric patients with hydrocephalus?

METHODS

Both the US National Library of Medicine PubMed/MEDLINE database and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words relevant to AIS use in children. Abstracts were reviewed, after which studies meeting the inclusion criteria were selected. An evidentiary table was assembled summarizing the studies and the quality of their evidence (Classes I-III). A meta-analysis was conducted using a random-effects model to calculate a cumulative estimate of treatment effect using risk ratio (RR). Heterogeneity was assessed using the chi-square and I(2) statistics. Based on the quality of the literature and the result of the meta-analysis, a recommendation was rendered (Level I, II, or III).

RESULTS

Six studies, all Class III, met our inclusion criteria. All but one study focused on a retrospective cohort and all but one were conducted at a single institution. Four of the studies failed to demonstrate a lowered infection rate with the use of an AIS. However, when the data from individual studies were pooled together, the infection rate in the AIS group was 5.5% compared with 8.6% in the SS group. Using a random-effects model, the cumulative RR was 0.51 (95% CI 0.29-0.89, p < 0.001), indicating that a shunt infection was 1.96 times more likely in patients who received an SS.

CONCLUSIONS

We recommend AIS tubing because of the associated lower risk of shunt infection compared to the use of conventional silicone hardware (quality of evidence: Class III; strength of recommendation: Level III).

RECOMMENDATION

Antibiotic-impregnated shunt (AIS) tubing may be associated with a lower risk of shunt infection compared with conventional silicone hardware and thus is an option for children who require placement of a shunt.

STRENGTH OF RECOMMENDATION

Level III, unclear degree of clinical certainty.

Ventricular shunt infections: immunopathogenesis and clinical management

Ventricular shunts are the most common neurosurgical procedure performed in the United States. This hydrocephalus treatment is often complicated by infection of the device with biofilm-forming bacteria. In this review, we discuss the pathogenesis of shunt infection, as well as the implications of the biofilm formation on treatment and prevention of these infections. Many questions remain, including the contribution of glia and the impact of inflammation on developmental outcomes following infection. Immune responses within the CNS must be carefully regulated to contain infection while minimizing bystander damage; further study is needed to design optimal treatment strategies for these patients.

Effect of introduction of antibiotic-impregnated shunt catheters on cerebrospinal fluid shunt infection in children: a large single-center retrospective study

OBJECT

Infection after both primary and revision shunt surgeries remains a major problem in pediatric neurosurgical practice. Antibiotic-impregnated shunt (AIS) tubing has been proposed to reduce infection rates. The authors report their experience with AIS catheters in their large pediatric neurosurgery department.

METHODS

The authors conducted a retrospective case review of consecutive shunt operations performed before (1993-2003) and after (2005-2009) introduction of AIS tubing, with analysis of shunt infection rates and causative organisms identified.

RESULTS

The historical control group consisted of 1592 consecutive shunt operations (657 primary insertions), and the AIS study group consisted of 500 consecutive shunt operations (184 primary insertions). Patients ranged in age from 0-17 years. In the historical group, 135 infections were identified (8.4%). In the AIS study group, 25 infections were identified (5%), representing a significant reduction (p < 0.005). The latency to diagnosis of infection was 23 days in the historical group and 139 days in the AIS study group. The infection rates in infants 0-6 months of age were 12.2% (historical group) and 6.7% (AIS group, p < 0.005), and in infants 7-12 months of age the rates were 7.9% (historical group) and 2.7% (AIS group, p < 0.005). In the historical control group, the frequency rank order of causative organisms was coagulase-negative staphylococcus (51.9%), Staphylococcus aureus (31.6%), streptococcus or enterococcus spp. (8.8%), gram-negative organisms (4.4%), and Propionibacterium acnes (2.2%). Organisms responsible for infections in AIS were S. aureus (40%), followed by streptococcus or enterococcus spp. (20%), P. acnes and coagulase-negative staphylococcus (both 16%), and gram-negative organisms (4%). No unusually antibiotic-resistant bacteria were identified in either group. The authors further subdivided the AIS group into those undergoing primary AIS insertion (Subgroup 1), those undergoing revision of non-AIS systems using AIS components (Subgroup 2), and those undergoing revision of AIS systems using AIS components (Subgroup 3). Infection rates were 1.6% in Subgroup 1, 2.5% in Subgroup 2, and 11.7% in Subgroup 3. Staphylococcus aureus was the most common organism identified in infections of the Subgroups 2 and 3.

CONCLUSIONS

Use of AIS tubing significantly improves shunt infection rates in both general pediatric and infant populations with no evidence of increased antibiotic resistance, which is in agreement with previous studies. However, the increased infection rate in revision surgery in children with AIS catheters in situ raises questions about their long-term application.

[Antibiotic-impregnated catheters. A useful tool against infection]

Progress in the treatment of hydrocephalus and particularly of cerebrospinal fluid (CSF) diversion surgery has been continuous and significant from cranial bandaging, which was one of the initial hydrocephalus treatments in the 16th century, to last-generation CSF shunts. However, infection currently remains the most frequent and serious complication despite the efforts made to prevent it. One of these current prevention measures is the use of antibiotic-impregnated catheters. A retrospective cohort study including shunts and external ventricular drains was designed to assess their efficacy in our scenario. The results show that rifampicin- and clindamycin-impregnated catheters are a helpful tool against CSF shunt-derived infection.

Antibiotic-impregnated shunt systems versus standard shunt systems: a meta- and cost-savings analysis

OBJECT

Infection is a serious and costly complication of CSF shunt implantation. Antibiotic-impregnated shunts (AISs) were introduced almost 10 years ago, but reports on their ability to decrease the infection rate have been mixed. The authors conducted a meta-analysis assessing the extent to which AISs reduce the rate of shunt infection compared with standard shunts (SSs). They also examined cost savings to determine the degree to which AISs could decrease infection-related hospital expenses.

METHODS

After conducting a comprehensive search of multiple electronic databases to identify studies that evaluated shunt type and used shunt-related infection as the primary outcome, 2 reviewers independently evaluated study quality based on preestablished criteria and extracted data. A random effects meta-analysis of eligible studies was then performed. For studies that demonstrated a positive effect with the AIS, a cost-savings analysis was conducted by calculating the number of implanted shunts needed to prevent a shunt infection, assuming an additional cost of $400 per AIS system and $50,000 to treat a shunt infection.

RESULTS

Thirteen prospective or retrospective controlled cohort studies provided Level III evidence, and 1 prospective randomized study provided Level II evidence. "Shunt infection" was generally uniformly defined among the studies, but the availability and detail of baseline demographic data for the control (SS) and treatment (AIS) groups within each study were variable. There were 390 infections (7.0%) in 5582 procedures in the control group and 120 infections (3.5%) in 3467 operations in the treatment group, yielding a pooled absolute risk reduction (ARR) and relative risk reduction (RRR) of 3.5% and 50%, respectively. The meta-analysis revealed the AIS to be statistically protective in all studies (risk ratio = 0.46, 95% CI 0.33-0.63) and in single-institution studies (risk ratio = 0.38, 95% CI 0.25-0.58). There was some evidence of heterogeneity when studies were analyzed together (p = 0.093), but this heterogeneity was reduced when the studies were analyzed separately as single institution versus multiinstitutional (p > 0.10 for both groups). Seven studies showed the AIS to be statistically protective against infection with an ARR and RRR ranging from 1.7% to 14.2% and 34% to 84%, respectively. The number of shunt operations requiring an AIS to prevent 1 shunt infection ranged from 7 to 59. Assuming 200 shunt cases per year, the annual savings for converting from SSs to AISs ranged from $90,000 to over $1.3 million.

CONCLUSIONS

While the authors recognized the inherent limitations in the quality and quantity of data available in the literature, this meta-analysis revealed a significant protective benefit with AIS systems, which translated into substantial hospital savings despite the added cost of an AIS. Using previously developed guidelines on treatment, the authors strongly encourage the use of AISs in all patients with hydrocephalus who require a shunt, particularly those at greatest risk for infection.

Progression of cerebrospinal fluid cell count and differential over a treatment course of shunt infection

OBJECT

The physiological reaction of CSF white blood cells (WBCs) over the course of treating a shunt infection is undefined. The authors speculated that the CSF WBC count varies with different infecting organisms in peak level and differential percentage of polymorphonuclear (PMN) leukocytes, lymphocytes, monocytes, and eosinophils. The authors hope to identify clinically useful trends in the progression of CSF WBCs by analyzing a large group of patients with successfully treated shunt infections.

METHODS

The authors reviewed 105 successfully treated cases of shunt infections at Riley Hospital for Children. The study dates ranged from 2000 to 2004; this represented a period prior to the routine use of antibiotic-impregnated shunt catheters. They analyzed the following organisms: coagulase-negative staphylococci, Staphylococcus aureus, Propionibacterium acnes, Streptococcal species, and gram-negative organisms. The initial CSF sample at diagnosis was analyzed, as were levels over 14 days of treatment. Model fitting was performed to generate curves for the expected progression of the WBC counts and the differential PMN leukocytes, lymphocyte, monocyte, and eosinophil percentages.

RESULTS

Gram-negative organisms resulted in a higher initial (p = 0.03) and peak WBC count with a greater differential of PMN leukocytes compared with other organisms. Propionibacterium acnes infections were associated with a significantly lower WBC count and PMN leukocytes percentage (p = 0.02) and higher eosinophil percentage (p = 0.002) than other organisms. The pattern progression of the CSF WBC count and differential percentages was consistent for all infections. There was an initial predominance of PMN leukocytes, followed by a delayed peak of lymphocytes, monocytes, and eosinophils over a 14-day course. All values trended toward zero over the treatment course.

CONCLUSIONS

The initial and peak levels of CSF WBCs vary with the infecting organisms. The CSF cell counts showed a predictable pattern during the treatment of shunt infection. These trends may be useful to the physician in clinical decision making, although there is a wide range of variability.

Antibiotic-impregnated catheters for the prevention of CSF shunt infections: a systematic review and meta-analysis

CSF infections are a serious complication of CSF shunts and external ventricular drains (EVDs). Antibiotic-impregnated catheters (AIC) have been tried in order to minimise the risk of such infections.

OBJECTIVES

To conduct a systematic review and a meta-analysis comparing AICs versus non-AICs used as ventriculo-peritoneal (VP) shunts or external ventricular drains (EVDs) in the neonatal population. The secondary aim was to include data from a paediatric and adult population if insufficient information was available from neonatal studies.

DATA SOURCES

PubMed (March 2011), EMBASE (March 2011), CENTRAL (1980-March 2011), and CINAHL (March 2011) were searched. Study selection. Both randomised controlled trials (RCTs) and observational studies were included.

RESULTS

Only three observational studies reported on the use of AI-VP shunt catheters in the neonatal population. Meta-analysis found a statistically significant difference favouring AI shunts (RR: 0.37; CI: 0.16, 0.86; p = 0.02). Twelve studies (one RCT, 11 observational; n = 3284) compared AI versus non-AI VP shunts in a paediatric and adult population. The RCT showed a trend towards benefit using the AICs (RR: 0.38; 95% CI: 0.11, 1.30; p = 0.12). A meta-analysis of the 11 observational studies showed a significant benefit in the AI group (RR: 0.37; CI: 0.23, 0.60; p = 0.0001; n = 3149). Similar benefits were noted for AI-EVDs in RCTs (RR: 0.19; 95% CI: 0.05, 0.64; p = 0.01; n = 472, two studies) and observational studies (RR: 0.31; 95 CI: 0.13, 0.74; p = 0.009; n = 2415, five studies).

CONCLUSIONS

A meta-analysis of mainly observational studies suggests that AICs may be an effective way of reducing the incidence of shunt and EVD infections. Well-designed multi-centre RCTs are urgently needed.