GOOD MORNING! Thursday, February 2, 2011

CSF Shunts Used in the setting of hydrocephalus to divert CSF to another part of the body for absorption Proximal portion is placed in one of the cerebral ventricles Distal portion can be internalized or externalized VP- ventriculoperitoneal VA- ventriculoatrial

Shunt Infection Rate of infection is 5 to 15% Highest rates of infection Initial month after placement Patients requiring several revisions Patients undergoing revision after treatment of infected shunt

Microbiology and Pathogenesis Most commonly via colonization with skin flora Occurs at time of surgery or post-op via breakdown of the wound or overlying skin Most predominant pathogen Staphylococci 50% are coag-negative Staph 30% are Staph aureus Direct contamination of distal end of shunt Bowel perforation or peritonitis Variety of organisms: streptococci, gram-negative bacteria (including Pseudomonas), anaerobes, mycobacteria, and fungi Hematongenous seeding

Clinical Manifestations Can present with few or no symptoms Sometimes symptoms only develop when shunt obstruction and malfuntion occurs Clinical signs of increased intracranial pressure Headache Nausea/vomiting Lethargy Mental status changes Meningeal signs may not be observed Fever +/-

Clinical Manifestations Symptoms may localize to distal or internal end of shunt VP Peritonitis (fever, abdominal pain, anorexia) VA Fever, bacteremia Subsequent endocarditis

Diagnosis CSF Direct aspiration of the shunt is preferred WBC count and diff, glucose, protein, Gram stain, culture Results can be challenging Less inflammation than bacterial meningitis Cell count abnormalities may be subtle White cell diff can be useful >10% neutrophils has 90% sensitivity for predicitng infection Culture results are critical for organism indentification and directing antibiotic therapy

Diagnosis (contd) Blood cultures Should be obtained Higher yield in VA shunts Imaging To look for evidence of ventriculitis or CSF obstruction Abdominal imaging may be useful to identify loculations at the distal end of VP shunts CT or ultrasound

Treatment 1) Removal of the device If not feasible, intraventricular antibiotics 2) External drainage 3) Parenteral antibiotics 4) Shunt replacement once CSF is sterile

Antibiotic Therapy Guided by CSF gram stain and culture Empiric therapy Vancomycin + gram-negative coverage For kids, cefotaxime Intraventricular antibiotics No controlled trials Potentially toxic Most experience with Vanc and Gent

Candida Shunt infection usually occurs within several months of the surgical procedure Results from implantation rather than hematogenous seeding Most patients had received antibiotics, had previous bacterial meningitis, or had abdominal complications (intestinal perforation) Symptoms and signs similar to bacterial shunt infection Fever and shunt malfunction Incidence is up to 17% in one study Clinical manifestations are subtle and slowly progressive

Candida Yeasts that reproduce by budding Non-albicans Candida species now account for more than half of invasive infections Candida parapsilosis can cause serious infections, especially in immunocompromised and debilitated hosts

Treatment of Candida CNS Infection First line therapy Amphotericin B Lipid formulation achieves higher concentrations in the brain +/- Flucytosine *Side effects Fluconazole Excellent CNS penetration, however treatment outcomes vary Use as step down treatment Voriconazole Excellent CSF concentrations Limited clinical experience

Treatment of Candida CNS Infection (contd) Posaconazole Does NOT achieve adequate CSF levels Echinocandins (caspofungin, micafungin, anidulafungin) Do NOT achieve adequate CSF concentrations

Antibiotic Duration No controlled trials to determine optimal duration Suggested approach (UpToDate): 1) If device removed, CSF chemistries are normal, and culture is positive for coag-negative staph shunt may be replaced on 3 rd day after removal if culture is negative 2) Coag-negative staph and abnormal CSF chemistries antibiotics for total time device remains in place and for 1 additional week following removal. CSF should be sterile prior to replacement

Antibiotic Duration (contd) 3) Shunt infections with more virulent pathogens (S. aureus, gram-negative, etc) warrant at least 10 days (14 to 21 for gram-negative). CSF should be sterile for 10 days prior to shunt replacement 4) If device is not removed, antibiotics for 7 to 10 days after sterilization of CSF

Prevention Careful adherence to sterile technique Antibiotic prophylaxis Warranted in the intial 24 hours after device placement Vancomycin is drug of choice due to predominant role of coag-negative staph Antibiotic-impregnated catheters Prophylactic catheter exchange Not effective for preventing infection

Male GU, Dr. Nass Noon Conference