Infections

Question 1

T/F

Antibiotics can be given 60 minutes prior to incision

Answer 1

False

Antibiotics should be given whenever they will be at the tissues during time of contamination

Question 2

Generally when using prophylactic antibiotics during an operation should you provide broad spectrum antibiotics?

Answer 2

There’s no benefit to broadening spectrum widely. Covering against the typical agents one would expect to cause an infection is often adequate.

Question 3

Is there added benefit to prophylactic antibiotics after post-op day 1?

Answer 3

No added benefit. The exception is when surgical drains are present.

Question 4

Do you need to use prophylactic antibiotics in a CEA?

Answer 4

Not necessarily. In low-risk procedures the cost to prevent may be more than the cost to treat.

Question 5

What is the ppx antibiotic of choice when skin flora are the most likely pathogen (e.g. coagulase neg or pos Staph)?

Answer 5

Cephalosporins (i.e. Cefazolin (Ancef)

Question 6

Can cephalosporins be provided as prophylactic antibiotics to patients with mild penicillin allergies (e.g. “rashes”)? What about patients with more severe immediate reactions?

Answer 6

Yes to patients with mild symptoms but not to those with more severe symptoms

Question 7

When cephalosporins are contraindicated as the prophylactic antibiotic of choice what is the next preferred agent?

Answer 7

Vancomycin

Question 8

Are penicillins a good choice for prophylactic antibiotics?

Answer 8

Not typically but within the group nafcillin is probably the best

Question 9

For CSF shunting procedures what is the antibiotic regimen f=of choice?

Answer 9

Cefazolin (or Nafcillin) and intrathecal gentamicin

Question 10

During procedures involving incision into oral or pharyngeal mucosa which prophylactic antibiotics are preferred?

Answer 10

Need coverage for anaerobic organisms so clindamicin and also gentamicin

Question 11

Most surgical site infections are due to what bacteria?

Answer 11

Staph aureus or Staph epidermidis

Question 12

In what population does Waterhouse-Friderichsen syndrome occur? What are symptoms?

Answer 12

Occurs in 10-20% of children

Question 13

What are four organisms which may be the causes of post-neurosurgical procedure meningitis?

Answer 13

S. aureus, Pseudomonas sp., Pneumococci, Enterobacteriaceae

Question 14

When post-neurosurgery meningitis is identified what are the empiric antibiotics of choice? What if Pseudomonas is discovered?

Answer 14

Vancomycin and ceftazidime

If Pseudomonas then add gentamicin

Question 15

What may etiologies of recurrent meningitis?

Answer 15

Dermal sinus, CSF fistula, Neuroenteric cysts

Question 16

Patients with post-cranial trauma meningitis are usually contaminated with organisms from where?

Answer 16

Nasal cavity

Question 17

What antibiotic for: S. pneumo or N. meningitidis meningitis?

Answer 17

PCN

2nd choice: chloramphenicol

Question 18

What antibiotic for: H. infleunza meningitis?

Answer 18

Non-penicillinase producing: ampicillin

Penicillinase producing: chloramphenicol

Question 19

What antibiotic for: group B Strep or Listeria monocytogenes meningitis?

Answer 19

Ampicillin

Question 20

What antibiotic for: S. aureus meningitis?

Answer 20

Vancomycin, PO rifampin, PO trimethoprim

If not MRSA then nafcillin in adult

Question 21

What antibiotic for: aerobic gram negative rod meningitis?

Answer 21

Ceftriaxone, or cefotaxime, or moxalactam

Question 22

What antibiotic for: P. aeruginosa meningitis

Answer 22

Ceftazidime and add aminoglycoside if severe infection present

Question 23

What antibiotic for: Candida?

Answer 23

Amphotericin
*Prior to amphotericin need to give NS to maintain renal blood flow, Demerol to protect against rigors, acetaminophen, and 5-fluorocytosine

Question 24

Children with shunt infection have greater risk of ______. Children with ventriculitis after shunting have a lower _____.

Answer 24

Greater risk of seizures (and risk of death)

Those with ventriculitis have lower IQ

Question 25

Early shunt infection is most often caused by what 3 pathogens?

Answer 25

S. aureus
S. epidermidis
Gram negative bacilli
* In neonates Strep. hemoliticus and E. coli predominate

Question 26

Almost all late shunt infections (>6 months after the procedure) are caused by what pathogen?

Answer 26

S. epidermidis

Question 27

Most fungal shunt infections are caused by what agent? What is the recommended therapy (both medical and surgical)?

Answer 27

Candida spp.

Antifungal therapy, remove contaminated shunt, place new EVD (especially if shunt-dependent), place new shunt 5-7 days later

Question 28

A shunt patient presents with UA demonstrating proteinuria and hematuria. What may be occurring?

Answer 28

Shunt nephritis caused by immune complex deposition in renal glomeruli

Question 29

Do antibiotics alone suffice for a shunt infection?

Answer 29

Not really, the shunt needs to be diverted or removed. Antibiotics alone are usually reserved for terminally ill patients, those with high anesthesia risk, or slit ventricles that are hard to catheterize

Question 30

What are empiric antibiotics in a shunt infection?

Answer 30

Vancomycin (may add PO rifampin to broaden)

If cultures come back non-MRSA and patient doesn’t have a PCN allergy then switch to nafcillin

Question 31

What antibiotic for: S. aureus and S. epidermidis shunt infections?

Answer 31

Intrathecal gentamicin and (IV nafcillin or cephalosporin)

Question 32

What antibiotic for: Enterococcus shunt infection?

Answer 32

Intrathecal gentamicin and IV/IT ampicillin

Question 33

What antibiotic for: aerobic gram negative rod shunt infection?

Answer 33

Antistreptococcal and anti-Pseudomonal aminoglycoside

Question 34

What is treatment for osteomyelitis of skull?

Answer 34

Antibiotics alone are not sufficient, need to perform surgical debridement of skull and close scalp without cranioplasty. Follow this with 6-12 weeks of antibiotics. A closure of the defect can be considered afterward.

Question 35

Relative to other mass lesions, at what speed do symptoms develop in patients with cerebral abscesses?

Answer 35

Rapidly

Question 36

What are the most common pathogens in cerebral abscesses?

Answer 36

Streptococcus but 60% are polymicrobial

Question 37

How do cerebral abscesses appear on imaging?

Answer 37

Enhancing ring on CT and T2MRI with contrast. On non-contrast T2MRI will see a low intensity ring with high signal edema surrounding the lesion. Unlike tumors abscesses have restricted diffusion on DWI (therefore high signal DWI and low signal ADC)

Question 38

What is treatment for cerebral abscess?

Answer 38

IV antibiotics. Some patients undergo needle drainage and fewer have exicison