Microbiology Induction for Neurosurgery trainees

1. Microbiology Induction for Neurosurgery trainees Kavita Sethi Consultant Microbiologist LTHT

2. LTHT Microbiology

3. Contact Details • Duty Microbiologist for  0113-392-3962 or -8580 interpretative & clinical advice Ext 25034 if need to contact myself (Contact via switchboard for urgent queries) For laboratory assistance within normal working hours (e.g. urgent samples)0113-392-3499 Results will NOT normally be given out by telephone if the result is already available on the results server

4. LEEDS HEALTH PATHWAYS • Neurosurgery, Neurology, Rehabilitation MedicineSpecialty Specific Treatment • Brain abscess and subdural empyema • Deep spinal infection in adults   • Herpes Simplex Encephalitis in adults GeneralTreatment • Clostridium Difficile Infection • Community Acquired Pneumonia • Hospital Acquired Pneumonia (Non-ventilated Patients) • Severe Sepsis Screening Tool and Resuscitation Care Bundle (Adults) • Urinary Tract Infections (UTIs) including acute pyelonephritis in Adults (≥ 16 years of age

5. Restricted Antimicrobial Policy •To slow the development of resistance to a drug by limiting its use • There are more suitable alternatives that are less expensive or less toxic • DOCUMENTED approval from one of the Medical Microbiologists or infectious diseases physicians prior to prescribing (antimicrobial code)

6. How do you evaluate infection

7. NORMOTHERMIA • An increase in body and brain temperature is associated with an increase in CBF, cerebral metabolic requirement for oxygen and oxygen utilisation, resulting in an increase in ICP and further cerebral ischaemia. • Pharmacological antipyretics and surface cooling.

8. Evaluation of fever in Neurosurgical patients • Nervous system is a sterile milieu. • Fever occurs in 25% of neurocritical care patients with 50% being noninfectious • Hypothalamic temp. • Majority of infections within the Neurocritical care units are nosocomial (device related infections)

9. Total white cell count and C-reactive protein surgery

10. Risk Factors • Admission for more than 48 hours • Mechanical ventilation • Trauma • Vascular catheterisation • Urinary catheterisation • Stress ulcer prophylaxis EPIC 1995

11. Respiratory infection Early Late Bacteremia GI infection UTIs Neurosurgical device related infections Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae Pseudomonas, Coliforms, Acinetobacter, MRSA Clostridium difficile Asymptomatic bacteruria in catheterised patients Coagulase negative Staphylococcus, P.acnes, Staphylococcus aureus Nosocomial infections on NITU

12. Postoperative bacterial meningitis • Low overall incidence • Variables • Clean or clean-contaminated • Antibiotic prophylaxis • Aetiology • Aerobic GNB (60-70%) • E.coli, K.pneumoniae, P.aeruginosa, Acinetobacter spp. • S.aureus • S.pneumoniae (dural defects/ CSF otorrhoea or rhinorrhoea) REMEMBER ASEPTIC MENINGITIS

13. Pathogenesis • What is on the skin goes in the wound • Most cases are a result of surgical wound infection • Independent risk factors : • GCS < 10 • Emergency surgery • CSF leakage • External CSF drainage

14. Diagnosis of bacterial meningitis post-neurosurgery Useful criteria Less helpful criteria high fever CSF glucose new neurological deficit CSF protein active CSF leak type of operation CSF leukocytosis presence of foreign material blood leukocytosis steroid use altered mental status neck stiffness headache / nausea Ross et al. Journal of Neurosurgery 1988; 69: 669-74

15. Diagnosis of Nosocomial meningitis • Challenging • Clinical • Indistinguishable from community-acquired meningitis • May be difficult to distinguish from neurological signs/ symptoms of underlying disease or associated with post-op period • LP must be performed to confirm diagnosis (CT first to establish safety) • CSF parameters may be altered due to surgery itself especially in the presence of SAH • CSF leucocytosis not infrequent • Antibiotics which achieve adequate CSF levels (guided by gram stain and culture) • Surgical management of wound infection/ persistent CSF leak

16. Excellent Ceftazidime Meropenem Metronidazole Rifampicin Chloramphenicol Useless Macrolides Aminoglycosides Clindamycin CSF Penetration of antibiotics

17. Additional points • Duration of therapy • S.aureus – 2 weeks • AGNB – up to 3 weeks • Vancomycin penetrates poorly into CSF and patient may fail to respond to systemic therapy • Implant an Ommaya reservoir and instill vancomycin directly into ventricles every 3rd day

18. Postoperative aseptic meningitis • Thought to be the result of irritation caused either by blood/ degradation products introduced into SAS during surgery • Indistinguishable from postoperative bacterial meningitis (clinical & CSF cell count and chemistry) • ? CSF lactate to distinguish • Approach • Empirical antibiotic therapy • If CSF sterile – discontinue antibiotics • Responds favourably to high dose corticosteroids

19. Empiric therapy

20. Antibiotic Prophylaxis for Basilar Skull Fracture? Meta Analysis • 12 studies, 1241 patients • 58% received antibiotics • Antibiotics did not prevent meningitis RR 1.15 (0.68 - 1.94) p=0.68 • CSF leakage subset RR 1.34 (0.75 - 2.41) p=0.36

21. Brain abscess • Hematogenous spread from extracranial site • Can arise from direct spread from mastoid and sinus infections • Corticomedullary junction • Frontal and parietal lobes most common • Posterior fossa <5% • Overall mortality rate has ranged from 0% to 24%. • Prognosis • the rapidity of progression before hospitalization • mental status onadmission

22. Bacteriology • 􀁺 Streptococci (70%) • 􀁺mixed infections (30% to 60%) • 􀁺 Streptococcus milleri group • 􀁺 oral cavity, appendix, and female genital tract • 􀁺 otopharyngeal infections , • 􀁺 IE • 􀁺Staphylococcus aureus10% to 15% • 􀁺 cranial trauma • 􀁺 IE • Neurosurgical procedure

23. Contd. • Bacteroides and Prevotella in 20% to 40% • 􀁺 mixed infection • Enteric gram-negative bacilli (Proteus species, Escherichia coli, Klebsiella and Pseudomonas) in 23% to 33% • 􀁺 otitic infection • 􀁺 Septicemia • 􀁺 neurosurgical procedures • 􀁺 immunocompromised • Rare pathogens : Nocardia, Mycobacterium tuberculosis, Listeria monocytogenes

24. Brain abscess • Blood cultures should be obtained when diagnosis is suspected • Lumbar puncture (LP) should be deferred in any case for which brain abscess is suspected because of the potential for CNS herniation and low likelihood of positive cultures. • Pus collected in a sterile universal container (NOT SWAB) should be sent to Microbiology for urgent microscopy, culture and sensitivity.

25. Cerebritis and abscess • Early cerebritis – (3-5 days) • Late Cerebritis -(4 to 14 days) Early Capsule Stage (Begins at 2 weeks following initial infection) Late capsule stage

26. Initial approach to the patient witha suspected brain abscess • Contrast CT or MRI should be performed • If single or multiple ring-enhancing lesions are found, the patient should taken urgently to surgery. • 􀁺 All lesions > 2.5 cm in diameter should be excised or stereotactically aspirated. • 􀁺 For abscesses in the early cerebritis stage or when the abscesses are < 2.5 cm in diameter, the largest lesionshould be aspirated for diagnosis and organism identification

27. Antimicrobial therapy • empirical antimicrobial therapy should be initiated on the basis of the patient’s predisposing conditions and the presumed pathogenesis of abscess formation Otitis media/mastoiditis/sinusitis Cefotaxime/ Metronidazole Post neurosurgical /traumaadd anti-staphylococcal cover • Use Ceftazidime as the 3rd generation cephalosporin if Pseudomonas aeruginosa is suspected

28. Brain Abscess - Surgical treatment • significant mass effect exerted by lesion • proximity to ventricle • poor neurological condition • Inability to obtain weekly CT scans • In patient undergoing medical treatment • Intervention, if neurological deterioration occurs, anatomic progression of abscess towards ventricles, or after 2 weeks of therapy if abscess is enlarged. Also consider if there is no decrease in abscess size by 4 weeks of treatment.

29. Shunt infections CSF shunts become infected by various routes: • Organisms directly colonize the shunt, usually at the time of surgery • Organisms reach the CSF and the shunt via haematogenous spread • Organisms travel along the shunt by retrograde spread (uncommon) • Coagulase-negative Staphylococci are isolated most commonly. Production of extracellular slime has been reported as being important in the pathogenesis of shunt infections

30. Clinical features • Variable • Fever • Signs of raised ICP • Evidence of shunt malfunction • Distal shunt infections can present with peritonitis

31. Shunt infections • CSF from shunt ( before antimicrobial therapy) • SHUNT REMOVAL • Proximal catheter, valve or shunt reservoir, distal catheter in three separate containers • Intrathecal +/- systemic antibiotic • Shunt replacement once the CSF sterile

33. EVD-related ventriculitis • Incidence between 10-17% • Risk • Lowest risk 1st 4 days that EVD is in-situ • Rises over next 10 days • Falls thereafter • Incidence not decreased by exchanging EVD at regular intervals • Aetiology • CNS (predominant)

34. Diagnostic approach Patient with EVD with symptoms and signs of ventriculitis CSF sample + Gram stain or + culture • Gram stain • and culture 2nd sample + Gram stain or + culture (same As 1st) Treat No treatment

35. Additional points • Collect CSF from EVD itself or the Ommaya reservoir, not the drainage bag • Treat CNS infections with intraventricular Vancomycin for 5-7 days • Product license does not cover this route • Not validated by clinical trials • Guarantees max concentrations of vancomycin at the site of infection • Avoids systemic toxicity • Cheaper than systemic therapy • No need to monitor levels

36. Hand Hygiene