Choice of Antibiotics in the prophylaxis and Treatment of
Common Neurosurgical Problems Chayooth Thanapornsangsuth
Fifth year medical student
Invasive potential of bacteria or other pathogens that are inoculated into wound during surgery that exceeds the capability of local and systemic host defense
>105 Increase potential of SSI Presence of foreign material (ex. VP shunt)
decrease size of minimal inoculation Gram positive bacteria biofilms shield
pathogen, inhibit action of antibiotics Primary reservoir=flora colonizing the skin
and paranasal sinuses
Pathogenesis of surgical site infection
Patients characteristics associated with surgical site of infection
1. Concomitant remote site infection eg. pneumonia, UTIs
2. DM 3. Cigarette smoking 4. Prolonged use of systemic corticosteroids 5. Obesity 6. Extreme age 7. Poor nutritional status 8. Others eg. U/D malignancies, use of
immunosuppressive agents in organ transplant patients
Risk Factors
Predict degree of microbial contamination at a surgical site and likelihood of developing a surgical site of infection(SSI)
Classification of wounds and predictors of surgical site infection
Wound Classification
Definition Examples
Clean An uninfected woundRespiratory, GI, GU tract not encounteredWound closed primarilyMay be drained with closed drainage system
Lumbar diskectomyTemporal lobectomy
Clean contaminated Respiratory, GI, GU tract entered under controlled conditionsNo usual contamination
Transsphenoidal pituitaryRetromastoid craniectomy for microvascular decompressionAcute open depressed skull fracture
Contaminated-open Acute accidental woundsMajor violation of sterile techniqueGross contamination from GI tractNonpurulent inflammation may present
Dirty/infected-old Traumatic wounds with retained devitalized tissuePurulent tissue encounteredPerforation of major viscera
Classification of surgical wounds
1. Intraabdominal procedure 2. Operation greater than 2 hours 3. Wound classified as contaminated or dirty 4. Operation performed on patients having
greater than three discharge diagnoses
Independent risk factors associated with development of surgical site infection(SSI) <SENIC project>
Definition 1. Prophylaxis- ATB administration for
procedures with minimal contamination of surgical site anticipated
2. Therapy- ATB administration for procedures with significant contamination
Antimicrobial prophylaxis
Techniques for surgical prophylaxis CDC Recommendations for Prevention of SSI
Category Definition
IA Strongly recommended for all hospitals and strongly supported by well-designed experimental or epidemiological studies
IB Strongly recommended for all hospitals and viewed as effective by experts in field and a consensus of Hospital Infection Control Practices Advisory Committee (HICPAC) based on strong rationale and suggestive evidence, even though definitive scientific studies may not have been done
II Suggested for implementation in many hospitalsRecommendations may be supported by suggestive clinical recommendations or epidemiological studies, a strong theoretical rationale, or definitive studies applicable to some but not all hospitals.
No recommendation; unresolved issue
Practices for which insufficient evidence or no consensus regarding efficacy exists
The prophylactic antimicrobial agent should be efficacious against the most common pathogens causing SSI for a specific operation(IA); for neurosurgery, this mandate excellent gram positive coverage against most common skin contaminants such as staphylococcal species and attention to the organism predominant in the surgeon institution
CDC Guidelines for the use of Prophylactic ATB
The ATB should ideally be administered intravenous within 30 minutes but not longer than 2 hours before the initial incision(IA)
Administer of the prophylactic antimicrobial agent as close as possible to the time of induction of anesthesia(II)
Prophylaxis should not be extended to the time of postoperative period(IB)
CDC Guidelines for the use of Prophylactic ATB
Additional intraoperative doses should be considered (a) during procedures whose duration exceeds the estimated half-life of the drug, (b) during operations associated with major blood loss, (c) during operations on morbidly obese patients (IB)
Vancomycin should not be administered routinely for category IB
CDC Guidelines for the use of Prophylactic ATB
1. Prophylactic ATB is not risk free -Vancomycin hypotensive episodes or
flushing -Aminoglycosides Ototoxicity -Penicillin 8% of patient suffer adverse
reactions 2. Costs
Considerations
1. Clean neurosurgical procedures 2. Foreign body implantation 3. Timing and duration of prophylaxis 4. Prophylactic ATB in patient with basilar
skull fractures 5. Prophylactic ATB for external ventricular
drains
Clinical Data regarding antimicrobial prophylaxis
Clean procedures Efficacy established Clean contaminated General surgical
procedures have clearly been shown to benefit from preoperative ATB
Dirty and contaminated cases Therapeutic rather than prophylactic
Clean neurosurgical procedures
For CSF shunt, the higher the baseline infection rate of CSF procedure, the more protective prophylactic ATB appeared to be. If the baseline infection rate <5% use other method of infection control such as rigorous aseptic technique
Foreign body implantation
Other foreign bodies eg. Intrathecal catheter, synthetic cranioplasties, deep brain and spinal cord electrodes, no controlled trial regarding the efficacy of prophylactic antibiotics.
Foreign body implantation
Timing- with in 2 hours of incision time Duration- procedures whose length exceeds
the half life of the prophylactic ATB repeat dose
Timing and duration of prophylaxis
No convincing data that supports the prophylactic use of ATB
1. Routine use of ATB will lead to resistance of more virulent organism than would otherwise be encountered
2. CSF analysis may fail to identify organism 3. Problem relating toxicity
Prophylactic ATB in patient with basilar skull fractures
External ventricular drains are used to monitor intracranial pressure and therapeutic drainage of CSF
Lumbar subarachnoid drains management of CSF leaks + administration of intrathecal medications
Prophylactic ATB for external ventricular drains
No clear evidence that this is beneficial Other than prophylactic ATP, other steps
that are important are strict aseptic technique during placement, tunneling of catheter away from insertion site, minimal entry into the system, changing catheter at specified interval.
Prophylactic ATB for external ventricular drains
1. Posttraumatic and postoperative bacterial meningitis
2. Post operative bone flap infection, cranial epidural abscess, and subdural emphysemas
3. Bacterial Brain abscess
Antibiotic Therapy of Neurosurgical Infections
Majority is caused by secondary complication of basilar skull fracture and CSF fistulae
Fracture of skull base + tearing of dura direct communication with paranasal sinuses, mastoid air cels bacteria ingress to subarachnoid space
Strep. pnemoniae + other Strep.spp about three-quarters of cases
Secondary bacterial meningitis Same ATB treatment with that occurs spontaneously
Posttraumatic and postoperative bacterial meningitis
Post operative bone flap infection- uncommon
-diagnosis- fever, pain, tenderness, erythema, swelling, fluctuance, drainage of purulent material from the incision
-risk factors- procedure of long duration, reoperation, trauma, exposure involving the air sinuses, poor irradiation of the scalp, use of foreign body drain, immunosuppression, excessive traffic in and out of the surgical suite.
Post operative bone flap infection, cranial epidural abscess, and subdural emphysemas
Treatment - if not ill-appearing or toxic wait until
cultures are obtained - appears ill or manifest systemic signs of
toxicity ATB start without delay Staphylococcus aureus accounts for most
cases
Post operative bone flap infection, cranial epidural abscess, and subdural emphysemas
Stapphylococci account for most postoperative infection
Many other organisms can be encounted with CEA
Initial empiric therapy should be broad spectrum
Parenteral ATB should be given 4-6 weeks
Cranial epidural abscess
ATB similar to as above In infants complication of bacterial
meningitis most commonly due to Haemophilus influenzae. In such case ampicillin or cefuroxime can be used with third generation cephalosporins as alternative agents
Subdural Empyema
1. Empiric therapy should be based on a thorough understanding of the microbiological flora that is anticipated based on individual clinical situation
2. Treatment should be adequate 3. Therapy should be adjusted as necessary
based on cultures
Bacterial Brain abscess
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