Intraabdominal Infections Flashcards
Secondary peritonitis
Occurs secondary to abdominal process
(Perforations, appendicitis, pancreatitis, diverticulitis, neoplasms, etc)
Microbiology of ileum
ileum = final section of small intestine
E.coli, Enterococcus, anaerobes
Microbiology of large intestine
Obligate anaerobes (bacteroides, clostridium)
E. coli
Streptococcus
Enterococcus
Klebsiella
Proteus
Enterobacter
Ascitic fluid in peritonitis
Protein: >3 g/dL
Exudate
Many WBC, primarily granulocytes
Treat peritonitis for <24 hours in these cases
- Bowel injury from trauma, repaired in 12 hours
- Intra-operative contamination
- Perforation of stomach, duodenum, proximal jejunum (If on antacids or malignancy, need longer)
- Acute appendicitis without evidence of perforation, abscess, peritonitis
Antibiotic options for mild-moderate peritonitis, community-acquired
Cefoxitin (2nd gen ceph with anaerobic coverage)
Cefazolin, cefuroxime, ceftriaxone + metronidazole
Ertapenem
Moxifloxacin
Cipro or levo + metronidazole
Tigecycline
*Most do not have Pseudomonas coverage, so cover for typical gram negative, gram positive, and anaerobes
High risk/severe peritonitis qualifications
APACHE II score > 15
Old
Poor nutrition/low albumin
Inability to achieve source control
Malignancy
Immunosuppression
Antibiotics for high risk/severe peritonitis
Zosyn
Ceftazidime or cefepime + metronidazole
Imipenem/cilastatin or meropenem
Cipro or levo + metronidazole
**Coverage for Pseudomonas + anaerobes
CIlastatin purpose for imipenem
Inhibits dehydropeptidase, which normally breaks down imipenem
Cilastatin will prolong activity of imipenem
Therapy duration for high risk/severe peritonitis
4 days post source control
Nonsevere C.diff labs
WBC <15
SCr <= 1.5
Severe Cdiff labs
WBC >= 15
SCr > 1.5
Fulminant Cdiff
Hypotension, shock, ileus, or megacolon
BI/NAP1 Cdiff strain
Produces more toxins
More likely for metronidazole failure, morbidity, mortality
Initial Cdiff episode treatment
Nonsevere/severe:
1. Fidaxomicin 200mg PO BID x10 days
2. Vancomycin 125mg PO QID x10 days
- If nonsevere and vanc/fidaxomicin unavailable, may use metronidazle PO 500mg TID x10 days.
Fulminant Cdiff initial treatment
Vancomycin 500mg PO QID x10 days
If ileus (unable to move food&waste through body):
1. Add metronidazole 500mg IV q8h
2. Add vancomycin 500mg in 100mL NS per rectum in enema QID
3. If ileus resolves, discontinue both.
First Cdiff recurrence after metronidazole tx
Vanco 125 PO QID x10 days
Or
Fidaxomicin 200mg PO BID X10 days
First Cdiff recurrence after vancomycin & fidaxomicin tx
Fidaxomicin 200mg PO BID x10 days (prefer) (even in first fidaxomicin failure)
Fidaxomicin extended (200mg PO BID x5 days, then 200mg daily for 20 days)
Vanco taper + pulse dose:
125mg PO QID x10-14 days,
then 125mg PO BID x7 days,
then 125mg PO daily x7 days
then 125mg PO q2-3 days for 2-8 weeks
Second & subsequent C. diff recurrence
-Fidaxomicin 200mg PO BID X10 days
-Fidaxomicin prolonged course
-Vanco prolonged taper & pulse dose
-Vanco 125mg PO QID x10 days, followed by rifaximin 400mg TID x20 days
-Fecal microbiotia (Rebyota) 150mL rectally x1 24-72 hrs after vanco/fidaxomicin
-Fecal microbiota (Vowst) 4 caps q24H x3 days; 2-4 days after vanco/fidaxomicin
Cdiff prophylaxis
Approriate if fidaxomicin not an option, >65 or immunocompromised w/ Cdiff in past 3 months, systemic ABX)
Vancomycin 125m PO daily (if on systemic ABX, discontinue 5 days after therapy complete)
Bezlotoxumab
MAB that binds Cdiff toxin B. Lower incidence of recurrent Diff
Use as ppx if high risk of recurrence:
-1 or more prior episode in previous 6 months
->65
-Immunocompromised
-Severe CDI
10mg/kg as single 60 min infusion, given during antibiotic therapy
Caution in CHF
Surgical prophylaxis timing
-60 minutes before incision
-60-120 minutes before incision if vancomycin or FQ
-Redose if surgery > 4 hours or considerable blood loss
Surgical prophylaxis antibiotics and dosing
Cefazolin 2gm (3gm if >120kg)
Ceftriaxone or cefoxitin 2gm
Clindamycin 900mg
Vancomycin 15mg/kg
Surgical prophylaxis antibiotic duration
Most do not need antibiotics after surgery wound closure
Cardiac procedure: 24-48 hours postop
Perforated appendicitis surgical prophylaxis
Cefoxitin 2gm or cefazolin + metronidazole or ertapenem 1gm before surgery and 4 days after
Colorectal surgical prophylaxis
IV + PO = lower rate of wound infection, leaks, mortality
Anaerobic and aerobic coverage
IV:
-Cefazolin or ceftriaxone + metronidazole
-Cefoxitin 2gm or Unasyn 3gm or ertapenem 1gm
-Gent/tobramycin 5mg/kg + clinda 900 or metronidazole
PO:
-Neomycin 1gm + erythromycin 1gm PO 2, 3, 10pm
-Neomycin 1gm + metronidazole 500mg 2, 3, 10pm
When antibiotics are recommended as prophylaxis postoperatively
Cardiothoracic vascular surgery
(3 doses postop)
Otherwise the preoperative dose should be sufficient
Broad spectrum ABX Associated with Cdiff
Carbapenems
Clindamycin
Cephalosporins, especially 3-4th gen
FQs
Cdiff clinical tests
Toxin A&B immunoassays: low sensitivity, moderate specificity
Glutamate dehydrogenase: high sensitivity, low specificity
NAAT: expensive but high sensitivity
