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|NI FEATURE: THE EDITORIAL DEBATE-- PROS AND CONS
|Year : 2016 | Volume
| Issue : 4 | Page : 610-611
The guilty microbes in shunt infection: Is there an emerging trend?
Department of Neurosurgery, Park Clinic, Kolkata, West Bengal, India
|Date of Web Publication||5-Jul-2016|
Department of Neurosurgery, Park Clinic, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chatterjee S. The guilty microbes in shunt infection: Is there an emerging trend?. Neurol India 2016;64:610-1
In spite of the surging interest in endoscopic third ventriculostomy (ETV), ventriculoperitoneal shunts continue to remain the most frequently performed technique of cerebrospinal fluid (CSF) diversion practised today. Infection of these shunts remains the most dreaded complication, and in their article Vikas Kumar et al., have rightly reiterated that complications of shunts remain feared and dreaded the most. In the background, there is increased evidence that thanks to rampant over-the-counter sale of antibiotics, bacterial resistance to conventional antibiotics remains a major threat in India today. It would, thus, be logical for each of us who perform shunts regularly, to analyse our own data regarding the microbiology of shunt infections in our individual or group hospital environment. To this aim, the authors deserve to be commended without any doubt.
It is appropriate to point out the change in the last decade in India. In 2006, in their paper, Sarguna  reported that coagulase negative Staphylococcus was the most common isolate from shunt tubes of patients with shunt infections (a finding echoed in the present study) whereas in the present study from Delhi, the authors seem to have grown microbes from the CSF in 23% of patients with shunt infections and grown a much lower percentage from the shunt tubes themselves. This would suggest that the majority of infections are without colonization from the shunt tubes but are directly from the bloodstream, a very worrying thought, and one which is not enough elaborated upon by the authors. However, the fact that revisions for infections were highest in patients with tuberculous meningitis suggests that poor nutrition and low immunity levels may be the main cause rather than local skin contamination. Is it that general condition of the patient is a more important determinant of shunt infection rather than local factors? In their paper, Rajkumar et al., also found that the majority of shunt infections occurred in children with post-meningitic and post-tuberculous hydrocephalus, again suggesting that nutritional and immunological factors may be more important than local skin flora (and as a corollary, the surgical technique) in the genesis of shunt infections in this country. Regarding antibiotic sensitivity, it may be pointed out that, whereas the earlier study  had shown that the majority of the isolates were sensitive to the third generation cephalosporin and quinolones, this present report shows the average sensitivity to these two groups of antibiotics to be only 30% and 20%, respectively. Is this change significant? The answer is unfortunately “No”, since even with the advantage of such large numbers, the authors have chosen not to do a statistical analysis to show the changes in the emerging trends. A temporal stratification of the cases would have been an invaluable statistical tool. Moreover, in spite of staphylococci being a major microorganism cultured, one wonders why vancomycin seems to have not been used by them at all. One other issue deserves to be mentioned in the context of shunt infections, and that is the re-infection rate. What was the reinfection rate of the authors? That is, what percent of patients who had shunts changed under what they felt was appropriate antibiotic cover, came back again with repeat infections. This is indeed the best guide as to whether the choice of antibiotics were appropriate or not, and mention of this would have highlighted that they got their choice of antibiotics right.
Does age affect the incidence of shunt infections? The answer has been answered many times before, and infants and younger children have a much higher incidence of shunt infections than adults do. Moreover, where pre-existing CSF infections (pyogenic or tuberculous) seem to be a major determinant of future shunt infections, would it not be reasonable to check the CSF PRIOR to the insertion of the shunts. It is our routine practice to do ventricular taps and check the CSF before insertion of shunts in infants, and this allows us to pre-treat CSF infections before placing the shunts. May be, if this were done, there would have emerged a different pattern of antibiotic résistance amongst small children and their older counterparts and adults. It must be conceded though that issues like relationship with age, or with duration from shunt insertion-to-infection were not analysed as a part of the aims of the present paper, whose sole purpose seems to be to highlight changes in antibiotic sensitivities.
Finally one has to disagree with the empirical statement made by the authors that one should use meropenem and teicoplanin with ceftriaxone in patients having shunt revisions for suspected infections. In the absence of statistically relevant data, this is a rather rash statement to make in a country with rapidly emerging antibiotic résistance. It is, however, a timely reminder that we may well be heading in that dangerous direction.
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Kumar S Ganesh, Adithan C, Harish BN, Sujatha S, Roy G, Malini A, et al
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Kumar R, Singh V, Kumar MVK. Shunt revision in hydrocephalus. Indian J Paediatr 2005;72:843-7.
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