Shunt infection

see also Shunt tunnel infection.

see also Ventriculoperitoneal shunt infection.

see Shunt Infection Epidemiology.

Cerebrospinal fluid shunts are often complicated by bacterial infections.

Rarely are fungal organisms implicated.

Staphylococcus epidermidis

see Cryptococcus neoformans

Shunt infection risk factors.

Cerebrospinal fluid shunt infection can be recalcitrant. Recurrence is common despite appropriate therapy for the pathogens identified by culture. Improved diagnostic and therapeutic approaches are required.

Clinicians who treat patients with unusual CSF shunts or more difficult first infections should have a high index of suspicion for reinfection after treatment is completed ¹⁾.

In eight children ≤18 years old undergoing treatment for culture-identified cerebrospinal fluid shunt infection. After routine aerobic culture of each cerebrospinal fluid sample, deoxyribonucleic acid (DNA) extraction was followed by amplification of the bacterial 16S rRNA gene and the fungal ITS DNA region tag-encoded FLX-Titanium amplicon pyrosequencing and microbial phylogenetic analysis.

The microbiota analyses for the initial cerebrospinal fluid samples from all eight infections identified a variety of bacteria and fungi, many of which did not grow in conventional culture. Detection by conventional culture did not predict the relative abundance of an organism by pyrosequencing, but in all cases, at least one bacterial taxon was detected by both conventional culture and pyrosequencing. Individual bacterial species fluctuated in relative abundance but remained above the limits of detection during infection treatment.

Numerous bacterial and fungal organisms were detected in these cerebrospinal fluid shunt infections, even during and after treatment, indicating diverse and recalcitrant shunt microbiota. In evaluating cerebrospinal fluid shunt infection, fungal and anaerobic bacterial cultures should be considered in addition to aerobic bacterial cultures, and culture-independent approaches offer a promising alternative diagnostic approach. More effective treatment of cerebrospinal fluid shunt infections is needed to reduce unacceptably high rates of reinfection, and one effective strategy may be reduction of the diverse microbiota present in infection ²⁾.

A systematic review using PubMed and SCOPUS identified studies evaluating the effect of a particular intervention on shunt infection risk. Systemic prophylactic antibiotic or antibiotic-impregnated shunt efficacy studies were excluded. A total of 7429 articles were screened and 23 articles were included.

Eight studies evaluated the effect of comprehensive surgical protocols. Shunt infection was reduced in all studies (absolute risk reduction 2.2-12.3 %). Level of evidence was low (level 4 in seven studies) due to the use of historical controls. Compliance ranged from 24.6 to 74.5 %. Surgical scrub with antiseptic foam and omission of a 5 % chlorhexidine gluconate preoperative hair wash were both associated with increased shunt infection. Twelve studies evaluated the effect of a single intervention. Only antibiotic-impregnated suture, a no-shave policy, and double gloving with glove change prior to shunt handling, were associated with a significant reduction in shunt infection. In a hospital with high methicillin-resistant staphylococcus aureus (MRSA) prevalence, a randomized controlled trial found that perioperative vancomycin rather than cefazolin significantly reduced shunt infection rates.

Despite wide variation in compliance rates, the implementation of comprehensive surgical protocols reduced shunt infection in all published studies. Antibiotic-impregnated suture, a no-shave policy, double gloving with glove change prior to device manipulation, and 5 % chlorhexidine hair wash were associated with significant reductions in shunt infection ³⁾.

In a report by Kestle et al., 2011, compliance with an 11-step protocol was shown to reduce CSF shunt infection at Hydrocephalus Clinical Research Network (HCRN) centers (from 8.7% to 5.7%). Antibiotic impregnated catheters (AICs) were not part of the protocol but were used off protocol by some surgeons. The authors therefore began using a new protocol that included AICs in an effort to reduce the infection rate further.

The new protocol was implemented at HCRN centers on January 1, 2012, for all shunt procedures (excluding external ventricular drains [EVDs], ventricular reservoirs, and subgaleal shunts). Procedures performed up to September 30, 2013, were included (21 months). Compliance with the protocol and outcome events up to March 30, 2014, were recorded. The definition of infection was unchanged from the authors' previous report.

A total of 1935 procedures were performed on 1670 patients at 8 HCRN centers. The overall infection rate was 6.0% (95% CI 5.1%-7.2%). Procedure-specific infection rates varied (insertion 5.0%, revision 5.4%, insertion after EVD 8.3%, and insertion after treatment of infection 12.6%). Full compliance with the protocol occurred in 77% of procedures. The infection rate was 5.0% after compliant procedures and 8.7% after noncompliant procedures (p = 0.005). The infection rate when using this new protocol (6.0%, 95% CI 5.1%-7.2%) was similar to the infection rate observed using the authors' old protocol (5.7%, 95% CI 4.6%-7.0%).

CSF shunt procedures performed in compliance with a new infection prevention protocol at HCRN centers had a lower infection rate than noncompliant procedures. Implementation of the new protocol (including AICs) was associated with a 6.0% infection rate, similar to the infection rate of 5.7% from the authors' previously reported protocol. Based on the current data, the role of AICs compared with other infection prevention measures is unclear ⁴⁾.

The combination of intraventricular gentamicin and vancomycin with systemic antibiotic therapy significantly decreased the incidence of perioperative shunt infection. It is presumed that intraventricular antibiotic therapy extends prophylactic antibiotic coverage into the CSF and prevents bacterial seeding ⁵⁾.

Shunt infection treatment.

see Shunt infection outcome.

A retrospective study compared the occurrence of cerebrospinal fluid infection related to use of either standard silastic catheters or hydrogel coated catheters (Bioglide, Medtronic). The enrolment was available to neurosurgery patients undergoing shunt surgery from October 2012 to 2015 in two centers.

The follow-up period was more than months.A total of 78 patients were included in the study. In 33 patients 35-cm hydrogel-coated ventriculoperitoneal shunts (VPS) were used, and in remaining 45 patients 35-cm standard silastic VPS catheters were used.

Infection occurred in 14 (17.9%) patients, including definite VPS-related CSF infection in 6 patients (7.7%) and probable infection in remaining 8 patients (10.3%). There was a significant difference found in patients with total infection between the two groups [RR (95% CI); 0.200 (0.050-0.803), P = 0.014]. Analysis of Kaplan-Meier curve estimates indicated significant statistical difference between the two catheter types in duration (log rank = 4.204, P < 0.05). Significant statistical differences were also found in the subgroups including previous CSF infection within 1 month (log rank = 4.391, P = 0.04), conversion of external ventricular drains to shunt (Log Rank = 4.520, P = 0.03), and hospital stay >1 month (log rank = 5.252, P = 0.02). There was no difference found between the two groups of the patients with other infections within 1 month. The follow-up period was of 36 months.The hydrogel coated catheter is a safe and related to lower infection rates for high-risk patients who underwent shunt surgery ⁶⁾.

A total of 431 patients who underwent their first cerebrospinal fluid shunt insertion at Children's Memorial Hospital over a 10-year period were retrospectively studied with regard to the relationship between the etiology of the hydrocephalus, age at the time of shunt placement, and infection rate. Forty percent of the patients had constrictive hydrocephalus and meningomyelocele, 33% congenital communicating or obstructive hydrocephalus, and 18% tumors. Intraventricular hemorrhage and meningitis accounted for the remaining 8%. Eighty-three percent of the patients were less than 1 year old at the time of surgery; 18% were 1 week old or younger. A total of 1,485 procedures were performed with an average of 3 procedures per patient. Ninety-six patients had infections, resulting in a 22% infection rate per patient and a 6% infection rate per procedure. No significant correlation was evident between etiology of the hydrocephalus and infection rate (P greater than 0.05), even though meningomyelocele patients seemed to be more prone to infection than congenital hydrocephalus patients (P = 0.06). Age at the time of shunt placement was related to infection rate, with younger patients having more infections than older ones (P less than 0.01). More in-depth analysis of the relationship between age and infection rate was possible in the meningomyelocele and congenital hydrocephalus groups, owing to the significant number of these patients that fell into each one of the subdivisions chosen with respect to age at the time of shunt placement. Meningomyelocele patients shunted in the first week of life have a higher infection rate than those shunted at 2 weeks of age or older (P less than 0.01) ⁷⁾.