Patient and Treatment Characteristics by Infecting Organism in Cerebrospinal Fluid Shunt Infection

Cerebrospinal fluid shunt infections in children

Cerebrospinal fluid (CSF) shunts are commonly used for the long-term management of hydrocephalus in children. Shunt infection remains a common complication, occurring in about 5%-15% of CSF shunts. This narrative review summarises key evidence from recent literature on the epidemiology, pathogenesis, clinical presentation, diagnosis, management, outcomes and prevention of CSF shunt infections in children. The majority of shunt infections occur due to contamination at the time of surgery, with coagulase-negative staphylococci and Staphylococcus aureus being the most common infecting organisms. Clinical presentations of shunt infection can be varied and difficult to recognise. CSF cultures are the primary test used for diagnosis. Other CSF and blood parameters may aid in diagnosis but lack sensitivity and specificity. Core aspects of management of shunt infections include systemic antimicrobial therapy and surgical removal of the shunt. However, many specific treatment recommendations are limited by a lack of robust evidence from large studies or controlled trials. Shunt infections may result in long hospital stays, worsening hydrocephalus, neurological sequelae and other complications, as well as death. Therefore, reducing the incidence of infection and optimising management are high priorities. Antibiotic prophylaxis at the time of shunt placement, improved surgical protocols and antibiotic-impregnated shunts are key strategies to prevent shunt infections. Nevertheless, further work is needed to identify additional strategies to prevent complications and improve outcomes.

Characterization of cerebrospinal fluid (CSF) microbiota at the time of initial surgical intervention for children with hydrocephalus

OBJECTIVE

To characterize the microbiota of the cerebrospinal fluid (CSF) from children with hydrocephalus at the time of initial surgical intervention.

STUDY DESIGN

CSF was obtained at initial surgical intervention. One aliquot was stored in skim milk-tryptone-glucose-glycerol (STGG) medium and the second was unprocessed; both were then stored at -70°C. Bacterial growth for CSF samples stored in STGG were subsequently characterized using aerobic and anaerobic culture on blood agar and MALDI-TOF sequencing. All unprocessed CSF samples underwent 16S quantitative polymerase chain reaction (qPCR) sequencing, and a subset underwent standard clinical microbiological culture. CSF with culture growth (either after storage in STGG or standard clinical) were further analyzed using whole-genome amplification sequencing (WGAS).

RESULTS

11/66 (17%) samples stored in STGG and 1/36 (3%) that underwent standard clinical microbiological culture demonstrated bacterial growth. Of the organisms present, 8 were common skin flora and 4 were potential pathogens; only 1 was also qPCR positive. WGAS findings and STGG culture findings were concordant for only 1 sample, identifying Staphylococcus epidermidis. No significant difference in time to second surgical intervention was observed between the STGG culture-positive and negative groups.

CONCLUSION(S)

Using high sensitivity methods, we detected the presence of bacteria in a subset of CSF samples at the time of first surgery. Therefore, the true presence of bacteria in CSF of children with hydrocephalus cannot be ruled out, though our findings may suggest these bacteria are contaminants or false positives of the detection methods. Regardless of origin, the detection of microbiota in the CSF of these children may not have any clinical significance.

A Refined, Controlled 16S rRNA Gene Sequencing Approach Reveals Limited Detection of Cerebrospinal Fluid Microbiota in Children with Bacterial Meningitis

Advances in both laboratory and computational components of high-throughput 16S amplicon sequencing (16S HTS) have markedly increased its sensitivity and specificity. Additionally, these refinements have better delineated the limits of sensitivity, and contributions of contamination to these limits, for 16S HTS that are particularly relevant for samples with low bacterial loads, such as human cerebrospinal fluid (CSF). The objectives of this work were to (i) optimize the performance of 16S HTS in CSF samples with low bacterial loads by defining and addressing potential sources of error, and (ii) perform refined 16S HTS on CSF samples from children diagnosed with bacterial meningitis and compare results with those from microbiological cultures. Several bench and computational approaches were taken to address potential sources of error for low bacterial load samples. We compared DNA yields and sequencing results after applying three different DNA extraction approaches to an artificially constructed mock-bacterial community. We also compared two postsequencing computational contaminant removal strategies, decontam R and full contaminant sequence removal. All three extraction techniques followed by decontam R yielded similar results for the mock community. We then applied these methods to 22 CSF samples from children diagnosed with meningitis, which has low bacterial loads relative to other clinical infection samples. The refined 16S HTS pipelines identified the cultured bacterial genus as the dominant organism for only 3 of these samples. We found that all three DNA extraction techniques followed by decontam R generated similar DNA yields for mock communities at the low bacterial loads representative of CSF samples. However, the limits of detection imposed by reagent contaminants and methodologic bias precluded the accurate detection of bacteria in CSF from children with culture-confirmed meningitis using these approaches, despite rigorous controls and sophisticated computational approaches. Although we did not find current DNA-based diagnostics to be useful for pediatric meningitis samples, the utility of these methods for CSF shunt infection remains undefined. Future advances in sample processing methods to minimize or eliminate contamination will be required to improve the sensitivity and specificity of these methods for pediatric meningitis. IMPORTANCE Advances in both laboratory and computational components of high-throughput 16S amplicon sequencing (16S HTS) have markedly increased its sensitivity and specificity. These refinements have better delineated the limits of sensitivity, and contributions of contamination to these limits, for 16S HTS that are particularly relevant for samples with low bacterial loads such as human cerebrospinal fluid (CSF). The objectives of this work were to (i) optimize the performance of 16S HTS in CSF samples by defining and addressing potential sources of error, and (ii) perform refined 16S HTS on CSF samples from children diagnosed with bacterial meningitis and compare results with those from microbiological cultures. We found that the limits of detection imposed by reagent contaminants and methodologic bias precluded the accurate detection of bacteria in CSF from children with culture-confirmed meningitis using these approaches, despite rigorous controls and sophisticated computational approaches.

Bacteria commonly associated with central nervous system catheter infections elicit distinct CSF proteome signatures

Background

Cerebrospinal fluid (CSF) shunt infection is a common and devastating complication of the treatment of hydrocephalus. Timely and accurate diagnosis is essential as these infections can lead to long-term neurologic consequences including seizures, decreased intelligence quotient (IQ) and impaired school performance in children. Currently the diagnosis of shunt infection relies on bacterial culture; however, culture is not always accurate since these infections are frequently caused by bacteria capable of forming biofilms, such as Staphylococcus epidermidis, Cutibacterium acnes, and Pseudomonas aeruginosa resulting in few planktonic bacteria detectable in the CSF. Therefore, there is a critical need to identify a new rapid, and accurate method for diagnosis of CSF shunt infection with broad bacterial species coverage to improve the long-term outcomes of children suffering from these infections.

Methods

To investigate potential biomarkers that would discriminate S. epidermidis, C. acnes and P. aeruginosa central nervous system (CNS) catheter infection we leveraged our previously published rat model of CNS catheter infection to perform serial CSF sampling to characterize the CSF proteome during these infections compared to sterile catheter placement.

Results

P. aeruginosa infection demonstrated a far greater number of differentially expressed proteins when compared to S. epidermidis and C. acnes infection and sterile catheters, and these changes persisted throughout the 56-day time course. S. epidermidis demonstrated an intermediate number of differentially expressed proteins, primarily at early time points that dissipated over the course of infection. C. acnes induced the least amount of change in the CSF proteome when compared to the other pathogens.

Conclusions

Despite the differences in the CSF proteome with each organism compared to sterile injury, several proteins were common across all bacterial species, especially at day 5 post-infection, which are candidate diagnostic biomarkers.

Cerebrospinal Fluid Shunt Infections: A Multicenter Pediatric Study

BACKGROUND

Infections complicate 5%-10% of cerebrospinal fluid (CSF) shunts. We aimed to describe the characteristics and contemporary pathogens of shunt infections in children in Canada and the United States.

METHODS

Descriptive case series at tertiary care hospitals in Canada (N = 8) and the United States (N = 3) of children up to 18 years of age with CSF shunt infections from July 1, 2013, through June 30, 2019.

RESULTS

There were 154 children (43% female, median age 2.7 years, 50% premature) with ≥1 CSF shunt infections. Median time between shunt placement and infection was 54 days (interquartile range, 24 days-2.3 years). Common pathogens were coagulase-negative staphylococci (N = 42; 28%), methicillin-susceptible Staphylococcus aureus (N = 24; 16%), methicillin-resistant S. aureus (N = 9; 5.9%), Pseudomonas aeruginosa (N = 9; 5.9%) and other Gram-negative bacilli (N = 14; 9.0%). Significant differences between pathogens were observed, including timing of infection (P = 0.023) and CSF leukocyte count (P = 0.0019); however, differences were not sufficient to reliably predict the causative organism based on the timing of infection or discriminate P. aeruginosa from other pathogens based on clinical features. Empiric antibiotic regimens, which included vancomycin (71%), cefotaxime or ceftriaxone (29%) and antipseudomonal beta-lactams (33%), were discordant with the pathogen isolated in five cases. There was variability between sites in the distribution of pathogens and choice of empiric antibiotics. Nine children died; 4 (44%) deaths were attributed to shunt infection.

CONCLUSIONS

Staphylococci remain the most common cause of CSF shunt infections, although antibiotic resistant Gram-negative bacilli occur and cannot be reliably predicted based on clinical characteristics.

Cerebrospinal Fluid Shunt Infections in Children: Do Hematologic and Cerebrospinal Fluid White Cells Examinations Correlate With the Type of Infection?

BACKGROUND

Cerebrospinal fluid (CSF) shunt infections in children represent an increasing problem in clinical practice. However, comprehensive clinical, laboratory and microbiologic data are scarce in pediatric age.

METHODS

We conducted a 10-year retrospective study to (1) analyze clinical, laboratory and microbiologic parameters associated with infections in children; (2) analyze results according to the type of catheter (medicated or not), type of infection (first or relapses), type of hydrocephalus (acquired and congenital), presence or not of bacteriemia; (3) describe antibiotic susceptibilities and their evolution during the study period.

RESULTS

Eighty-seven children with shunt infection and 61 children with mechanical shunt malfunction were enrolled. Fever, vomit, leukocytosis and elevated C-reactive protein were more frequent in the infected group (P < 0.001), while neurologic symptoms developed more frequently in the noninfected group (10.3% vs. 27.87%; P = 0.006). Local signs of inflammation and abdomen distension were similarly reported in the 2 groups. Children with medicated shunts had lower cell count in the CSF (12/mm3) compared with those with nonmedicated shunts (380/mm3; P < 0.0001). Gram-negative bacteria were more common in the not-medicated catheters (90.91% vs. 50% of cultures; P = 0.04). Gram-negative bacteria were identified in 50.67% of CSF cultures, Gram-positive bacteria in 53.33% and fungi were observed in 5.33%. Sixteen children (18.4%) had also a positive blood culture. Enterococci isolation was associated with relapsed infections (37.50% vs. 15.25%; P = 0.05).

CONCLUSIONS

Our study shows that the diagnosis and management of children with shunt infections are challenging. Prospective studies with a comprehensive approach focusing on patient, medical, microbiologic and surgical risk factors for first infection are urgently needed.

Antimicrobial use in central nervous system infections

PURPOSE OF REVIEW

Central nervous system (CNS) infections are associated with high rates of morbidity and mortality. The purpose of this review is to summarize current antimicrobial therapies, as well as, updates in the management of community-acquired meningitis and healthcare-associated meningitis and ventriculitis.

RECENT FINDINGS

Due to the increasing rates of multidrug resistant and extensively-drug resistant organisms, available antimicrobials are limited. Novel treatment options include newer systemic antimicrobials and antimicrobials that have previously limited data in the management of CNS infections. Although limited by retrospective data, intrathecal (IT) and intraventricular (IVT) routes of administration offer the opportunity for antimicrobials that conventionally have minimal cerebrospinal fluid (CSF) penetration to achieve high CSF concentrations while minimizing systemic exposure.

SUMMARY

Updates in the use of systemic, IT, and IVT antimicrobials offer promise as therapeutic options for CNS infections. Additional pharmacokinetic and prospective data are needed to confirm these findings.

Risk factors for pediatric surgical site infection following neurosurgical procedures for hydrocephalus: a retrospective single-center cohort study

Background

Infection is a major complication following cerebral spinal fluid (CSF) diversion procedures for hydrocephalus. However, pediatric risk factors for surgical site infection (SSI) are currently not well defined. Because a SSI prevention bundle is increasingly introduced, the purpose of this study was to evaluate risk factors associated with SSIs following CSF diversion surgeries following a SSI bundle at a single quaternary care pediatric hospital.

Methods

We performed a retrospective cohort study of patients undergoing CSF diversion procedures from 2017 to 2019. SSIs were identified prospectively through continuous surveillance. We performed unadjusted logistic regression analyses and univariate analyses to determine an association between SSIs and patient demographics, comorbidities and perioperative factors to identify independent risk factors for SSI.

Results

We identified a total of 558 CSF diversion procedures with an overall SSI rate of 3.4%. The SSI rates for shunt, external ventricular drain (EVD) placement, and endoscopic third ventriculostomy (ETV) were 4.3, 6.9 and 0%, respectively. Among 323 shunt operations, receipt of clindamycin as perioperative prophylaxis and presence of cardiac disease were significantly associated with SSI (O.R. 4.99, 95% C.I. 1.27–19.70, p = 0.02 for the former, and O.R. 7.19, 95% C.I. 1.35–38.35, p = 0.02 for the latter). No risk factors for SSI were identified among 72 EVD procedures.

Conclusion

We identified receipt of clindamycin as perioperative prophylaxis and the presence of cardiac disease as risk factors for SSI in shunt procedures. Cefazolin is recommended as a standard antibiotic for perioperative prophylaxis. Knowing that unsubstantiated beta-lactam allergy label is a significant medical problem, efforts should be made to clarify beta-lactam allergy status to maximize the number of patients who can receive cefazolin for prophylaxis before shunt placement. Further research is needed to elucidate the mechanism by which cardiac disease may increase SSI risk after shunt procedures.

Cutibacterium acnes Central Nervous System Catheter Infection Induces Long-Term Changes in the Cerebrospinal Fluid Proteome

Cutibacterium acnes is the third most common cause of cerebrospinal fluid (CSF) shunt infection and is likely underdiagnosed due to the difficulty in culturing this pathogen. Shunt infections lead to grave neurologic morbidity for patients especially when there is a delay in diagnosis. Currently, the gold standard for identifying CSF shunt infections is microbiologic culture. However, C. acnes infection often results in falsely negative cultures; therefore, new diagnostic methods are needed. To investigate potential CSF biomarkers of C. acnes CSF shunt infection we adapted a rat model of CSF catheter infection to C. acnes. We found elevated levels of interleukin-1β (IL-1β), IL-6, chemokine ligand 2, and IL-10 in the CSF and brain tissues of animals implanted with C. acnes-infected catheters compared to sterile controls at day 1 postinfection. This coincided with modest increases in neutrophils in the CSF and, to a greater extent, in the brain tissues of animals with C. acnes infection, which closely mirrors the clinical findings in patients with C. acnes shunt infection. Mass spectrometry revealed that the CSF proteome is altered during C. acnes shunt infection and changes over the course of disease, typified at day 1 postinfection by an acute-phase and pathogen neutralization response evolving to a response consistent with wound resolution at day 28 compared to a sterile catheter placement. Collectively, these results demonstrate that it is possible to distinguish C. acnes infection from sterile postoperative inflammation and that CSF proteins could be useful in a diagnostic strategy for this pathogen that is difficult to diagnose.

Cutibacterium acnes: the Urgent Need To Identify Diagnosis Markers

Cutibacterium acnes role is well described during acne but remains a mystery regarding its implication in bone and prosthesis or cerebrospinal fluid shunt infections. The main issue is that these low-grade symptom infections are difficult to diagnose and lead to irreversible and grave sequelae for patients. Consequently, there is an urgent need to find new biomarkers to accelerate the diagnosis of disease, an issue addressed by Beaver et al. thanks to a promising proteomic approach.

Treatment strategies for cerebrospinal shunt infections: a systematic review of observational studies

OBJECTIVE

A systematic review was conducted of studies comparing time to cerebrospinal fluid (CSF) sterilisation or rate of recurrence with different treatment strategies for CSF shunt infections.

METHODS

A librarian-directed search was conducted of Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid Medline Daily and Ovid Medline, Ovid Embase, Wiley Cochrane Library, CINAHL Plus with Full Text via EBSCOhost, Scopus Advanced Search, and Web of Science Core Collection from 1990 to May 2019. Studies of any design that compared outcomes in groups of any age with different management strategies were included. Studies that compared complete versus incomplete shunt removal were excluded. Quality assessment was performed with the Newcastle-Ottawa Scale.

RESULTS

The search identified 2208 records, of which 8 met the inclusion criteria. All were cohort studies of moderate quality. Four studies compared the duration of antibiotics; none demonstrates that a longer course prevented recurrences. Two studies analysed addition of rifampin, with one showing a decrease in recurrences while the other had a small sample size. No studies analysed the addition of intraventricular antibiotics, but one showed equally good results with once versus twice daily administration. One study reported no difference in recurrences with placement of antibiotic-impregnated catheters. Recurrence rates did not differ with shunt replacement minimum of 7 days vs less than 7 days after CSF became sterile. There were no recurrences in either group when shunt replacement was performed after sterile CSF cultures were obtained at 24 vs 48 hours after antibiotics were discontinued. A new shunt entry site did not decrease recurrences.

DISCUSSION

The main limitations are the lack of high-quality studies, the small sample sizes and the heterogeneity which precluded meta-analysis. Addition of rifampin for staphylococcal infections may decrease relapse but requires further study.