Journal of The Academy of Clinical Microbiologists

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 21  |  Issue : 1  |  Page : 29--33

Ten-year retrospective study on ventriculoperitoneal shunt infections from a university teaching hospital, South India


Sushma Krishna1, Kavitha R Dinesh1, Tintu Abraham1, Dilip Panikar2, Sanjeev Singh3, Shamsul Karim1,  
1 Department of Microbiology, Amrita Institute of Medical Sciences, Kochi, Kerala, India
2 Department of Neurosurgery, Amrita Institute of Medical Sciences, Kochi, Kerala, India
3 Department of Infection Control Department and Administration, Amrita Institute of Medical Sciences, Kochi, Kerala, India

Correspondence Address:
Dr. Sushma Krishna
St. Martha's Hospital, Nrupatunga Road, Bengaluru, Karnataka
India

Abstract

BACKGROUND: Ventriculoperitoneal shunt insertions are one of the important neurosurgical procedures done to enhance the neurological functions and improve the survival of patients with hydrocephalus. However, shunt infections are associated with an increased risk of morbidity and the mortality of 30%–40%. The study objective was to evaluate the clinical features, aetiology, resistance pattern and outcome of patients with cerebrospinal fluid (CSF) shunt infections over a 10-year period (2001–2010) amongst the microbiologically-proven cases. METHODOLOGY: Retrospective chart review was carried out to evaluate the age, sex and aetiology of hydrocephalus, biochemical parameters, clinical features and outcome of the culture-positive cases. RESULTS: Out of the 184 post-procedure and initial (<24 months) CSF samples received, 28 of them were culture positive with a growth of 36 isolates. The shunt infection rate (unadjusted) was found to be 15.21%. Seventeen were male and 11 were female. Thirteen were children below the age of 1 year, 3 between 7 and 30 years and 12 were above 50 years. Congenital hydrocephalus and Post-meningitis were the commonly noted presentations (n = 9, 32.1%) patients. Fever (64.3%) and vomiting (46.4%) were the most common clinical symptoms. CSF pleocytosis (n = 13), low glucose (n = 5) and elevated proteins (n = 18) were seen, respectively, of the 18 records available. A total of 19 patients recovered from the episode and five documented deaths were noted. Three of the isolates persisted over 10 days with repeat isolations. The most common causative microorganism was Coagulase Negative Staphylococcus (CONS) n = 13 (36.5%) (in vitro resistance to methicillin was 36.3% and to gentamicin was 45.4%). CONCLUSION: CONS continues to be a challenge to neurosurgeons in the treatment of shunt infections. Adequate prophylactic antibiotics based on the local susceptibility pattern should be administered besides strengthening the infection control protocols of the hospital. Surveillance of healthcare-associated infections may well extend to shunt infections at the locations where insertions are carried out.



How to cite this article:
Krishna S, Dinesh KR, Abraham T, Panikar D, Singh S, Karim S. Ten-year retrospective study on ventriculoperitoneal shunt infections from a university teaching hospital, South India.J Acad Clin Microbiol 2019;21:29-33


How to cite this URL:
Krishna S, Dinesh KR, Abraham T, Panikar D, Singh S, Karim S. Ten-year retrospective study on ventriculoperitoneal shunt infections from a university teaching hospital, South India. J Acad Clin Microbiol [serial online] 2019 [cited 2019 Nov 18 ];21:29-33
Available from: http://www.jacmjournal.org/text.asp?2019/21/1/29/264255


Full Text



 Introduction



Ventriculoperitoneal (VP) shunts are used for drainage of the cerebrospinal fluid (CSF) to maintain a specific intracranial pressure. The mainstay of surgical treatment of hydrocephalus involves placement of VP shunts. Post-ventriculostomy data worldwide suggest shunt infection as the most common complication of CSF shunt insertion.[1] Post-operative shunt infections occur in 2%–41% of cases in most neurosurgical units throughout the world in different settings, making them a common cause of shunt failure.[2],[3] Shunt infections are associated with extended hospital stay and the cost and morbidity of additional surgeries for relocation or removal.[4] For years, coagulase-negative Staphylococcus (CONS) (52.8%–88.9%) has been implicated as the most common agent involved in VP shunt infections followed by Staphylococcus aureus (12%–40%).[5] Many risk factors have been reported to be associated with increased risk of infection such as usage of gastrostomy tube, younger age group of patients (6–12 months), prior neurosurgery and subsequent revisions.[6] We conducted a retrospective study of 184 patients who underwent shunt insertions in our institution during a 10-year period. The objective of the study was to evaluate the clinical features, the aetiology, the resistance pattern and outcome of patients with microbiologically-proven CSF shunt infections over a 10-year period.

 Methodology



Hospital setting

The study was conducted at a superspeciality university teaching hospital, a 1500-bedded tertiary healthcare centre. It is the major provider of medical care for ~500,000 area inhabitants from various parts of the state. Hospital lodges 21-bedded surgical neurointensive care unit and two neurosurgery wards where the shunted patients are monitored. On an average, 15–25 shunt insertions are carried out annually. The inserted shunts are not coated with antimicrobial agents. As per the pre-operative protocol followed, single-dose cefazolin is given perioperatively to the patients as antibiotic prophylaxis at the time of anaesthesia induction.

Study population

One hundred and eighty-four post-shunt procedure CSFs were subjected to microbiological culture from January 2001 to January 2011. Laboratory diagnosis of shunt infection was documented with CSF cell counts, biochemical tests, bacteriological culture and antibiotic susceptibility testing. CSF was inoculated on sheep blood agar, MacConkey agar and chocolate agar for recovery of most of the expected routine pathogens (excluding anaerobes). Isolates were identified by their standard biochemical reactions and susceptibility pattern recorded.[7],[8] A chart review of microbiologically-positive cases documenting the demographical and clinical details was carried out during the first quarter of 2011. Ethical committee approval was sought. Shunt infection was defined if both of the following criteria summarised was present (5): (1) the presence of an organism isolated from CSF culture or shunt tip culture with clinical presentation of acute bacterial meningitis or with signs and symptoms of shunt malfunction or obstruction and (2) At least one of the parameters of bacterial inflammation in CSF-leucocyte count of 0.25 × 109/l (>50% polymorphonuclear leucocytes), CSF lactate >3.5 mmol/L, CSF glucose-to-serum glucose ratio <0.4 and CSF glucose (<2.5 mmol/L). The later criteria were taken into consideration wherever the CSF findings were available.

 Results



Out of the 184 CSF samples received, 28 of the samples were culture positive with 36 isolates (shunt infection rate at 15.21%). The group comprised 17 males and 11 females. Both the adult and paediatric (<14 years) group had 14 patients each. Children <1 year were 13 in number, 3 of them in 7–30 years and 12 above the age of 50 years. Most infections (20 [62%]) manifested within one–two months after shunt surgery. Congenital hydrocephalus and Post-meningitis were the commonly noted underlying conditions of Shunt infections respectively (n = 9, 32.1%) [Table 1]. Over 50% of the patients recovered (n = 19), five deaths were recorded (n = 3 in adult, n = 2 paediatric), while the remaining were lost for follow-up. Four of these patients died of multi-organ failure and sepsis, while one adult had an unrelated cause. Of the 18 records available for CSF analysis, all 18 patients showed elevated proteins, 2 showed high glucose CSF and 13 patients showed pleocytosis [Table 2]. The most common causative organism was CONS, n = 13 (36.1%) followed by Gram-negative organisms grouped together (n=14) [Figure 1]. The patient-organism distribution with age split is given [Table 3]. Multidrug-resistant Acinetobacter spp. (n = 2), methicillin-resistant Staphylococcus aureus (MRSA) (n = 2) and extended-spectrum β-lactamases producing Enterobacteriaceae (n = 3) were recorded. CONS was persistently isolated ten times, Acinetobacter Spp five times in adult patients and Pseudomonas aeruginosa four times in paediatric patient (multiple isolations). Ceftriaxone was administered in methicillin-sensitive strains and Vancomycin in resistant strains and for MRSA patients. Piperacillin-tazobactum with amikacin was administered in most as the Gram-negative bacilli cover. The duration of therapy ranged from seven to 21 days. No bacteraemia or concomitant culture-proven infection was noted in the records accessed. The resistance pattern of the organisms isolated is listed [Table 4] and [Table 5].{Table 1}{Table 2}{Figure 1}{Table 3}{Table 4}{Table 5}

 Discussion



Shunt infection rates range from 2% to 41% worldwide and our study estimated the infection rates at our institution as 15.2%. Paediatric age group is the most susceptible population and our results agree with the same. The study showed hydrocephalus and fever as the most common presentation; however, shunt-associated infections among adults may present with non-specific clinical signs. While the study showed that the contributing CSF analysis among majority of patients showed pleocytosis, elevated proteins and low-to-normal glucose levels; Sarguna and Lakshmi and Conen et al. reported that in all of their respective studied cases, the CSF revealed no pleocytosis and no fall in the glucose levels.[9],[10] Therefore, biochemical parameters and clinical presentation may not always be consistent and a high index of suspicion may be required for diagnosing shunt-associated infections. Radiology (computed tomography and magnetic resonance imaging) of the brain may pick up early blockade in pre-existing hydrocephalus, meningomyelocele, etc. Culture remains the accepted routine for diagnosing shunt infections. It may be suggested to send the cultures on timely basis post-catheter in situ.

As in this study, CONS has been the most frequently isolated organism in most of the studies. The eradication of organisms which are colonised in shunts has always been a great challenge to the treating surgeon. Studies support that in majority of cases, the causative organism was present at the operative site prior to and during surgery. Colonised shunts may stop functioning well mechanically due to blockade. Being skin commensals, a direct wound contamination during surgery facilitates entry. The hospital infection control team needs to pay special attention to this area and step-up on the protocols with strict asepsis pre-operatively and intra-operatively to prevent colonisation. The Hydrocephalus Clinical Research Network has demonstrated that by following strict infection control protocols of what we would want to call as a shunt infection prevention bundle or a checklist for prevention (such as minimising implant and skin edge manipulation, reducing human traffic in the operating room, choosing the procedure as the first in the morning, avoiding CSF leakage, double gloving, minimising the duration of surgery (<30 min), administering antibiotic prophylaxis, hair clipping, applying chlorhexidine to the operating site, waiting three min following skin antisepsis (0.5% chlorhexidine was used as skin disinfectant in our hospital), scrubbing hands with povidone-iodine or chlorhexidine and injecting antibiotic into the shunt reservoir, etc.), the infection rate came down by 3.1% (P = 0.0028).[11] This package protocol may worth be a trial at many centres (including ours) instead of just focusing on individual interventions randomly, mostly pre-operative antibiotics. Recently, from the home country, a modified Choux (1992) protocol was tested and results were found promising in their study.[12] CONS is notorious for producing biofilms, thus making it difficult for the penetration of antibiotics.[13] Understanding the pathogenesis of biofilms as undertaken recently at the National Institute of Mental Health and Neurosciences may be vital in arriving at strategies to be employed for prevention.[12] Antibiotic-impregnated catheters with Rifampicin, Clindamycin and silver tried elsewhere need to be evaluated for success rates on a larger scale, keeping the cost and efficacy in mind.[14] On the other hand, Gram-negative bacterial colonisation of the skin is not common but could be introduced by an asymptomatic bowel perforation resulting in distal contamination of the VP shunt catheter and retrograde progression of infection. Shunt removal/relocation/exteriorisation may at times become a definitive measure in the management of shunt infection in persistent frustrating isolations.

In our study group, first-generation cephalosporins were administered as prophylaxis. However, the results of the study showed that a large percentage of CONS (36%) were methicillin-resistant, thus limiting the use of penicillin group and cephalosporins, the most commonly used Gram-positive cover across several centers. CONS also showed a higher percentage of resistance to aminoglycosides in this study of 31%–45.4%. 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 ( first line for methicillin-sensitive strains) for patients undergoing CSF shunt procedures.[15] Alarming as it is, based on our local sensitivity pattern; new prophylaxis of vancomycin with cephalosporin combination needs to be considered with adequate dosing for achieving better cure and focusing on striking a balance between judicious antibiotic use and misuse. Shunt infections may be roped in for monitoring and surveillance under device-associated hospital-acquired infections in hospitals.

 Conclusion



CONS continues to be a challenge to neurosurgeons in the treatment of shunt infections. A high index of suspicion may be required for diagnosing shunt-associated infections as the biochemical parameters and clinical presentation may not always be consistent. Adequate prophylactic antibiotics based on the local susceptibility pattern should be administered; local yearly analysis of isolates and monitoring the trend of antimicrobial susceptibility will help in picking up the increasing resistance rates at the hospital. Infection control protocols of the hospital need further strengthening with trying out various measures to prevent the colonisation of shunt catheters with CONS. Surveillance of healthcare-associated infections may well extend to shunt infections at the locations where insertions are carried out.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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