Shunt Infections in Hydrocephalus Patients

Shunt infections in case of patients of hydrocephalus treated with CSF shunts. Topic includes diagnosis and management based on latest guidelines in 2024.

1. Shunt infections Dr Malik Jauhar

2. Epidemiology Acceptable shunt infection rate: < 5 – 7% (many published series rate ~20% due to di ff erent patient population). Risk of early infection after shunt surgery: reported 3 – 20% per procedure ( ≈ 7%). 50% of staph infections occur within 2 weeks; 70% within 2 mos. Source is often the patient ’ s own skin. ≈ 3% of operations CSF is already infected (CSF during insertion is recommended).

3. Morbidity of shunt infections in children Children with shunt infections have an increased mortality rate and risk of seizure Those with myelomeningocele who develop ventriculitis after shunting have a lower IQ compared to those without infection. Mortality ranges from 10 – 15%.

4. Risk factors for shunt infection Many factors have been blamed. Some documented include: ●   young age: myelomeningocele, waiting till 2 weeks old may significantly lower the infection rate ●   length of procedure ●   open neural tube defect

5. Pathogens Early infection Most commonly: ●  Staph. epidermidis (CONS): 60–75% (most common) ●  S. aureus ●  Gram-negative bacilli: 6–20% (may come from intestinal perforation) In neonates E. coli and Strep. hemolyticus dominate.

6. Pathogens Late infection (> 6 months after procedure) Risk: 2.7–31% per patient (6%). Almost all are S. epidermidis. “Late” shunt infections may be due to: ●  an indolent infection due to Staph. epidermidis ●  seeding of a vascular shunt during episode of septicemia (probably very rare) ●  colonization from an episode of meningitis

7. Pathogens Fungal infections Candida spp. responsible for majority of fungal ventricular shunt infections. Usually occurs in children < 1 year of age . Incidence: 1 – 7%. The 4th leading pathogen causing meningitis in neurosurgical patients in 1 study Higher incidence in abdominal infections and in patients with previous bacterial meningitis. CSF typically shows: elevated WBCs and protein, normal glucose.

8. Pathogens Fungal infections Management recommendations: Remove contaminated shunt (important than in bacterial infections) fresh external ventricular drain (if patient is shunt-dependent) antifungal therapy fresh shunt after ≥ 5 – 7 days of therapy and clinical response antifungal agents for 6 – 8 weeks

9. Presentation Signs and symptoms Non-specific syndrome: fever, N/V, H/A, lethargy, anorexia, irritability. Shunt malfunction; 29% of patients with shunt malfunction had positive cultures. Erythema and tenderness along shunt tubing Distal infection of VP shunts may mimic acute abdomen. Neonates may manifest as apneic episodes, anemia, hepatosplenomegaly, and stiff neck.

10. Presentation Signs and symptoms S. epidermidis infections tend to be indolent (smoldering). GNB infections usually cause more severe illness abdominal findings are more common fever, usually intermittent and low grade. Shunt nephritis: chronic low level infection of ventriculovascular shunt causing immune complex deposition in renal glomeruli, characterized by proteinuria and hematuria.

11. Presentation Blood tests WBC: < 10K in one fourth of shunt infections. It is > 20K in one–third. ESR: rarely normal in shunt infections. Blood cultures: positive in less than one–third of cases.

12. Presentation CSF: WBC is usually not >100 cells/mm3. Gram stains may be positive ≈ 50% (yield with S. epidermidis is much lower). Protein is elevated, glucose low or normal. Rapid antigen tests for community acquired meningitis not helpful for the organisms of shunt infections. CSF cultures negative in 40% of cases (higher yield if CSF WBC count is >20K).

13. Presentation Evaluation of shunt for infection 1. history and physical determining presence of above signs and symptoms a) history suggestive of infection at another site ●  exposure to others with viral syndromes, including sick siblings ●  GI source (acute gastroenteritis). Often associated with diarrhea. ●  otitis media (check tympanic membranes) ●  tonsillitis/pharyngitis ●  appendicitis (peritoneal inflammation may impede VP shunt outflow) ●  URI ●  UTI ●  pneumonia b) Physical exam to R/O meningismus (stiff neck, photophobia)

14. Presentation 2. Bloodwork WBC count with DLC b) acute phase reactants: ESR & CRP c) blood cultures 3. Shunt Tap: Done in cases of suspected shunt infection. Clip hair (do not shave) and prepare carefully to avoid introducing infection. Gram stained CSF smear GNB have higher protein and lower glucose, and neutrophils predominate

15. Presentation 4. I maging a) CT: usually not helpful for diagnosing infection. Ependymal enhancement when it occurs is diagnostic of ventriculitis. CT may demonstrate shunt malfunction b) Abdominal U/S or CT: abdominal pseudocyst is suggestive of infection 5. LP: usually NOT recommended. H azardous in obstructive HCP with non functioning shunt. D oes not yield pathogen even in communicating HCP, especially if infection is limited to ventriculitis.

16. Treatment Antibiotics alone (without removal of shunt hardware) Eradication of infections without removal of hardware has been reported, lower success rate Requires protracted treatment (up to 45 days) Problems associated: infected CSF into peritoneum (reduced CSF absorption, abdominal tenderness to full-blown peritonitis or vascular system (shunt nephritis, sepsis). Often requires at least partial shunt revision at some point. Therefore recommended only in patients terminally ill, anesthetic risk, or slit ventricles that might be difficult to catheterize.

17. Treatment Removal of shunt hardware In most instances, during the initial treatment with antibiotics: the shunt is either externalized (i.e., tubing is diverted at some point distal to the ventricular catheter and connected to a closed drainage system) or sometimes the entire shunt may be removed. In the latter case, some means of CSF drainage is provided in shunt-dependent cases either by insertion of EVD, or intermittent ventricular taps or LPs (with communicating HCP). EVD allows easy monitoring of CSF flow, control of ICP, and repeated sampling for signs of resolution of infection (normalization of WBC count and surveillance cultures).

18. Treatment Removal of shunt hardware In addition, EVD allows for possible administration of intrathecal antibiotics. In symptomatic patients or those with a positive CSF culture, any hardware removed should be cultured as only ≈ 8% are sterile in shunt infections. Skin organisms are fastidious and may take several days to grow. Abdominal pseudocyst, fluid should be drained through the peritoneal catheter before removing it.

19. Treatment Antibiotics Empiric antibiotics 1. Vancomycin (adult) 15 mg/kg IV q 8–12 hours to achieve trough 15–20 mg/dl for MRSA coverage + Cefepime 2 g IV q 8h or Meropenem 2 g q 8h to cover gram-negative pathogens. Streamline therapy based on culture and sensitivity results 2. Intraventricular injection of preservative-free antibiotics may be used in addition to IV therapy. Clamp EVD for one hour after injection

20. Treatment Treatment for specific organisms Positive cultures from shunt hardware removed at the time of shunt revision in the absence of clinical symptoms or a positive CSF culture may be due to contamination and do not always require treatment. 1. S. aureus and S. epidermidis a) if methicillin sensitive: nafcillin or oxacillin ± IT vancomycin b) ifmethicillinresistant:continueIVvancomycin+POrifampin±ITvancomycin 2. Enterococcus: IV ampicillin ± IT gentamycin 3. Other streptococci: either antistreptococcal or above enterococcal regimen

21. Treatment 4. Aerobic GNR: base on susceptibilities. Both IV beta-lactam & IT aminoglycoside indicated 5. Serratia marcescens: rare cause of VP shunt infection, high morbidity warrants aggressive antibiotic therapy (IV ceftriaxone + IT aminoglycoside) and surgical therapy 6. Corynebacterium spp. & Proprionibacterium spp. ( diphtheroids ) a) if PCN sensitive: use enterococcal regimen above b) If PCN resistant: IV + IT Vancomycin

22. Treatment 7. Candida spp.: Systemic antifungal therapy and removal of shunt is warranted. Liposomal Amphotericin B 3–4 mg/kg IV daily + flucytosine 25 mg/kg PO QID Avoid echinocandins (antifungal drugs that inhibit synthesis of glucan in the fungal cell wall) as they have poor CNS penetration

23. Subsequent management Once the CSF is sterile × 3 days Convert the EVD to a shunt If EVD was not used, still recommended the shunt be replaced with new hardware. Continue antibiotics an additional 10–14 days.

24. Managing ventriculoperitoneal shunts in patients with peritonitis Peritonitis may occur as a result of: perforation of a viscus (sometimes penetration by peritoneal catheter tip, more common with obsolete Raimondi wire-reinforced tubing) Spontaneous bacterial peritonitis: absence of an identifiable intra-abdominal source. Most commonly diagnosed in patients with cirrhotic ascites Seeding through a VP shunt in a patient with a shunt infection: predominantly gram-positive, cutaneous organisms

25. Managing ventriculoperitoneal shunts in patients with peritonitis Concerns following an episode of peritonitis in a patient with VP shunt: 1. Ascending infection: Uncommon, especially in acute setting while on antibiotics with shunts containing a one-way valve (as most do). CSF grows predominantly mixed, gram-negative intestinal flora 2. Contamination of distal shunt: prevents permanent eradication of infection (appendicitis in the absence of peritonitis does not produce shunt infection) 3. Shunt malfunction due to distal shunt obstruction: often result of walling off of the catheter tip, usually by omentum in reaction to the infection

26. Managing ventriculoperitoneal shunts in patients with peritonitis Management recommendations following an episode of peritonitis: 1. Immediate appropriate treatment of peritonitis, (e.g. ruptured appendix: appendectomy and appropriate antibiotics) Initial attempt to address shunt not being mandatory 2. Cases have been managed successfully by cleaning off the peritoneal catheter with bacitracin solution then wrapping the catheter in a bacitracin-soaked lap sponge until the time comes to close abdomen

27. Managing ventriculoperitoneal shunts in patients with peritonitis 3. If peritonitis was diffuse or if shunt catheter is believed to have been contaminated option is to externalize the distal catheter, preferably once patient has stabilized from peritonitis (afebrile, stable vital signs, normal WBC) a) Externalization to avoid pulling the contaminated catheter up towards sterile portions of the shunt. Reopening the skin incision used for inserting the peritoneal catheter Making a second incision over the shunt tubing, well above this entry point. The catheter is then divided at the upper incision. The catheter is grasped at lower incision and pulled, extracting both ends (peritoneal end and end just cut). The remaining catheter coming from above is connected to an external drainage system

28. Managing ventriculoperitoneal shunts in patients with peritonitis b)  CSF cultures are monitored daily c)  if 3 consecutive cultures are negative, a new distal catheter may be implanted d)  if cultures continuously grow organisms, then shunt may be contaminated and should be replaced new shunt system e)  when it is time to replace the shunt, some authors recommend using an alternative site other than the peritoneum, but this is not mandatory

29. Prevention

30. Prevention

31. Prevention

32. External ventricular drain (EVD)-related infection Epidemiology ▶ Incidence: EVD infection is approximately 9.5%. ▶ Risk factors. Factors associated with EVD infections: ●  duration of EVD ●  site leakage ●  blood in CSF (IVH and SAH) ●  irrigation and flushing

33. Microbiology ●  unlike organisms that cause community-acquired meningitis, those causing neurosurgical procedure meningitis are slow to grow on cultures ●  the usual organisms that cause EVD-related infections: ○  organisms colonizing the skin: especially the scalp ( CoNS , Staph aureus, and Propionibacterium acnes) ○ healthcare environment: S. aureus, methicillin sensitive/resistant, gram-negative bacteria: E. coli, Klebsiella, pseudomonas, and Acinitobacter species, can be multi-drug resistant. ●  can form a polysaccharide layer (biofilm) on the surface of catheters, which increases the resistance to antimicrobials.

34. Clinical presentation Clinical signs and symptoms (nonspecific; as a result of the underlying pathology (e.g., intracranial hemorrhage or hydrocephalus) ●  change in mental status ●  fever: alternative sources: ICH, central fever, thrombotic episodes, drug fevers non-CNS infection: blood-borne infections, hospital- acquired pneumonias, and UTI ●   meningismus : stiff neck, Brudzinski or Kernig sign.

35. Diagnosis ▶ Blood parameters: can suggest the diagnosis but should not be relied upon exclusively. ●  a prospective study showed likely EVD infections in the presence of these parameters: Peripheral WBC count > 15k in EVD infections (vs. < 11k in non-infected) ●  serum inflammatory markers: there is very limited literature on the diagnostic utility of ESR and CRP. Procalcitonin alone was found not to be helpful.

36. Diagnosis ▶ CSF parameters: Limited studies on diagnostic accuracy in post-craniotomy meningitis and ventriculitis. Sometimes the surgery itself may produce chemical meningitis The following could help in confirming underlying EVD infection. ●   Low CSF glucose: ratio of [CSF glucose]/[blood glucose] < 0.2 ●  CSF pleocytosis > 1000 or rising cell index ●  CSF protein not a reliable predictor Routine CSF sampling: CSF sampling should be performed only when symptoms appear. No evidence of benefit to obtaining CSF cultures or cell count at the time of EVD insertion

37. Principles of management ●  it is difficult to achieve high CSF antimicrobial levels due to blood-CSF barrier ●  some hospital-acquired organisms have higher MICs (minimal inhibitory concentration) for antimicrobials than community-acquired organisms ●  organisms often form biofilms on the catheters which resist antimicrobial penetration. For this reason, catheter should be removed

38. Principles of management ●  Empiric Antibiotics: initiate if ventriculitis is suspected once sampling has been obtained ○   if no penicillin allergy: –  Vancomycin as infusion or divided doses (2–3) of 60 mg per kg of body weight per day after a loading dose of 15 mg per kg of body weight, aiming for trough (15–25 mcg/ ml) PLUS –  Ceftazidime 2g IV q 8 hrs or Cefepime 2g IV q 8 hrs ○   for penicillin allergy: –  Vancomycin as infusion or divided doses (2–3) of 60 mg per kg of body weight per day after a loading dose of 15 mg per kg of body weight PLUS –  Meropenem 2g IV q 8 hrs or Aztreonam 2g IV q 6 hrs

39. Principles of management ●  switch to more selective agents as appropriate, based on culture and susceptibility when they become available ●  duration of treatment should be individualized to the patient Rule of thumb: treat for 2 weeks if infection is S. aureus and S. epidermidis and 3 weeks if it is gram-negative

40. Principles of management

41. Principles of management ●  Failing to respond to systemic treatment or resistant organism might require intrathecal/intraventricular administration. Choose the antimicrobial based on susceptibility. Dosages for intraventricular antibiotics: ○  Vancomycin: 5mg-slit ventricles, 10mg-normal sized ventricles, 15–20mg-enlarged ventricles ○  Aminoglycoside: Dosing can be tailored to ventricular size. Frequency adjusted based on drain output: OD for >100 ml/day, Alt. day for 50–100 ml/day, every 3rd day if drainage < 50 ml/day – gentamicin:4–8mg – tobramycin:5–20mg – amikacin:5–30mg ○   Colistimethate sodium: 10mg CMS (125,000 IU) or 3.75mg CBA (Colistin Base units) ○  Daptomycin: 2–5 mg

42. Principles of management ●  after IT administration of an antimicrobial, clamp the drain for 15–60 minutes to allow antimicrobial concentration to equilibrate in CSF before opening drain ●  Expert opinion: wait at least 7–10 days after the CSF cultures become sterile to implant a shunt if needed

43. Prevention ●   T unneling > 5 cm away from the burr hole ●   A ntibiotic coated catheters (e.g., Rifampin + minocycline) significantly reduce the risk of EVD infection ●   R outine catheter exchange at day 5 did not show reduction in the rate of infection Therefore a single catheter may be employed as long as clinically required. ●   P rolonged antibiotic prophylaxis while the EVD is in place does not decrease the risk of infection and may select for resistant organisms. However one dose pre-procedure antimicrobial may be administered

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