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|NI FEATURE: THE EDITORIAL DEBATE-- PROS AND CONS
|Year : 2016 | Volume
| Issue : 4 | Page : 608-609
The war against shunt infections – fighting with our backs to the wall!
R Girish Menon
Department of Neurosurgery, Kasturba Medical College, Manipal, Karnataka, India
|Date of Web Publication||5-Jul-2016|
R Girish Menon
Department of Neurosurgery, Kasturba Medical College, Manipal, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Menon R G. The war against shunt infections – fighting with our backs to the wall!. Neurol India 2016;64:608-9
Ventriculo-peritoneal shunt surgery has exclusive indications even in this endoscopic era. Yet, their effectiveness is often overshadowed by complications such as infection and malfunction. Shunt infections remain a dreaded complication with an incidence ranging from 2.2% to 41%. Any effort to analyze and provide a solution to this vexed problem is welcome and this attempt by Kumar et al., needs to be complimented.
Kumar et al., analysed a total of 156 samples of cerebrospinal fluid (CSF) and shunt tubes out of which, 79 (50.6%) samples had growth of an organism either in the CSF [36 (23.1%)], in the shunt tubing [16 (10.2%)], or in both [27 (17.3%)]. The most common organisms grown in the cultures were Staphylococcus aureus and coagulase-negative Staphylococcus in the Gram-positive group and Escherichia More Details coli in the Gram-negative group. This microbial pattern is similar to what has been reported globally. What is alarming is their subsequent observation that the sensitivity pattern of both Gram-negative and Gram-positive bacteria has shown a significant decreasing sensitivity for various commonly used antibiotics. They have observed an increasing resistance to all cephalosporin and quinolones. They found that the Gram-positive bacteria isolated were more sensitive to linezolid and imipenem, meropenem, and tigecyciline with a sensitivity of more than 60%. Although not adequately reported, these statistics are similar across India. Their concluding remarks that meropenem and teicoplanin with ceftriaxone should be used for prophylaxis should ring warning bells in the entire neurosurgical fraternity. The grounds on which they suggest this recommendation for prophylaxis is not forthcoming in the article and we assume that it was based on the sensitivity pattern observed. Surprisingly, vancomycin, an often used antibiotic against Staphylococcus does not figure in their list. Now that we have exhausted our last arsenal, one is thus left to wonder and ponder at our impending helplessness, when these microbes develop resistance to meropenem and teicoplanin. That day is not far, for sure.
Shunt infection is related to both patient factors and surgeon practices. Prematurity, age less than 6 months, length of the preoperative hospitalization, current ongoing infections, history of previous shunt infection, the history of multiple shunt revisions, post-infectious hydrocephalus (especially tuberculous), post-hemorrhagic hydrocephalus, and hydrocephalus due to spina bifida are a few of the patient related factors predisposing to infection.,, Many of these patient factors are beyond our control and these limitations need to be accepted. But, what we do have control over, and where we fail to exercise adequate caution, include some surgical practices—the most important among them being failure to adopt a guideline-based technique for shunt surgery, and the avoidance of an indiscriminate use of antibiotics.
Shunt infection rates per patient range from 10% to 22% and around 6.0% per procedure, with 90% of infections occurring within 30 days of surgery. Biofilms play an important role in the development of shunt infections. Biofilms are protected communities of bacteria or fungi capable of attaching to surfaces by forming a heterogeneous structure composed of cellular elements and a complex self-produced matrix. Biofilms are able to evade the host immune defense and are more resistant to antimicrobial treatment. Staphylococcal strains are better able to form biofilms and are more resistant to phagocytosis by neutrophils and antibacterial treatment, which explains their dominance in shunt infections.
The 2013 clinical practice guidelines for antimicrobial prophylaxis in surgery do not recommend their routine use. However, other evidence supports the use of systemic prophylactic antibiotics in preventing shunt infection but also warn that the benefits last only for the first 24 hours, postoperatively. Recent guidelines by the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Surgical Infection Society, and the Society for Healthcare Epidemiology of America  recommend the use of a single dose of cefazolin for patients undergoing CSF shunt procedures. Clindamycin or vancomycin may be used as alternatives in patients with documented b-lactam allergy, and vancomycin, for patients colonized with meticillin-resistant S. aureus. Use of antibiotics, both for prophylaxis and treatment, needs to be customized based on the institute's antibiotic profile and an universal guideline is not applicable. However, a conscientious approach to avoid the indiscriminate use of antibiotics is the need of the hour.
The WHO-sponsored study on surgical errors found that application of a standardized preoperative checklist effectively reduced mortality rates in a broad range of surgical procedures across multiple international centers and shunt surgery is no different. Protocol based surgeries have proven to reduce shunt infections in four randomized studies.,, These protocols generally include a uniform surgical technique, minimizing of implant and skin edge manipulation, reduction in human movement in the operating room, performing the procedure as the first one in the morning, avoidance of CSF leakage, use of double gloving, ensuring that the surgery is a short procedure (<30 min), and administering antibiotic prophylaxis. Additional steps include placing a sign on the operating room door restricting traffic, positioning the patient's head away from the main door, hair clipping, removal of dirt and adhesive materials, applying chlorhexidine to the surgical field, waiting three minutes following the skin antisepsis, scrubbing hands with povidone iodine or chlorhexidine, using non-latex double gloves and drapes, administering intravenous antibiotics, and injection of antibiotics into the shunt reservoir. Kestle et al., observed that the application of a standardized protocol for 1571 CSF shunt surgery procedures reduced the infection rate from 8.8% to 5.7% (P = 0.0028). They also observed that the practice of injecting1 ml (10 mg/ml) of vancomycin mixed with 2 ml (2 mg/ml) of gentamicin into the shunt reservoir with a 25-gauge needle (or smaller) after the shunt procedure and prior to closure of wound may be beneficial. This technique, which attempts to overcome the pharmocokinetic limitations of perioperative antibiotics, is seldom practiced in India and is probably worth emulating.
Two surgical practices, which are yet to pass the test of evidence based scrutiny, are the use of antimicrobial sutures and the use of antibiotic-impregnated shunts.,, Bayston et al., found that antibiotic (clindamycin and rifampicin) impregnated catheters do not prevent microbial adherence but do kill 100% of attached cells in 48–52 hours, even in the presence of a biofilm. Studies favoring these techniques have been small, non-randomized and retrospective, and larger prospective trials are required before they become standard-of-care practices.
Efforts are on to circumvent the multiple barriers of antibiotic evasion employed by the biofilm. Silver-impregnated catheters, which may prevent the initial adherence of bacteria to the catheter, anti-biofilm catheter lock therapies and hydrogels capable of eradicating the biomass and reducing microbe viability of the biofilm are some therapies under experimental trial. Immunotherapy or vaccines against S. epidermidis biofilms is yet another revolutionary idea under active consideration.
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