Intra-Abdominal Infections Flashcards
What are the intra-abdominal infections?
intraperitoneal: completely covered with visceral peritoneum - stomach, 1st part duodenum, jejunum, ileum, transverse colon, sigmoid colon, liver, spleen
retroperitoneal: partially covered with peritoneum - kidneys, ureters suprarenal glands, rectum
What are the types of intra-abdominal infections?
diverticulitis (+/- perforation/abscess), appendicitis (+/- rupture), cholecystitis, intra-abdominal abscess, cholangitis, peritoneal dialysis related peritonitis, spontaneous bacterial peritonitis, necrotizing pancreatitis
What is primary peritonitis?
peritoneal dialysis related peritonitis
spontaneous bacterial peritonitis
What is secondary peritonitis?
diverticulitis (+/- perforation/abscess), appendicitis (+/- rupture), cholecystitis, intra-abdominal abscess, cholangitis, necrotizing pancreatitis
What is an uncomplicated infection?
▪Confined within visceral structure (e.g., gall bladder, liver, spleen, kidneys)
▪Does not extend into peritoneum
What is a complicated infection?
▪Extends beyond a single organ into the peritoneal space and associated with peritonitis
What is a community-acquired infection?
▪Occurs within 48 hours of hospital admission, no healthcare exposure
▪Caused by normal intra-abdominal flora
What is a healthcare-associated infection?
▪Occurs after 48 hours of hospital admission
▪Healthcare exposure in last 12 months (e.g., hospitalization, recent surgery)
What is spontaneous bacterial peritonitis? What patients are at high risk?
▪No obvious source of bacterial contamination
▪Patients at highest risk: Hepatic failure and ascites – alcoholic cirrhosis; Continuous ambulatory peritoneal dialysis (CAPD)
What are the causative pathogens of spontaneous bacterial peritonitis?
Most commonly monomicrobial
▪Escherichia coli!!! and other Enterobacterales (e.g., K. pneumoniae)
▪Streptococci
▪Enterococci
▪Staphylococcus aureus and coagulase negative staphylococci (more common with CAPD)
What is the clinical presentation of spontaneous bacterial peritonitis?
▪Abdominal pain
▪Nausea, vomiting, diarrhea
▪Fevers, chills
▪Reduced/absent bowel sounds
▪Altered mental status/encephalopathy
What is the diagnosis of spontaneous bacterial peritonitis?
▪Signs and symptoms of infection
▪Ascitic fluid analysis
⎻ Low ascitic fluid protein (< 2.5 g/dL)
⎻ Absolute neutrophil count > 250/mm3
look at TNC body fluid and bands/neutrophils body fluid
What are recommended treatment options for spontaneous bacterial peritonitis? - empiric selection
ceftriaxone, cefepime, piperacillin/tazobactam, meropenem
What are recommended treatment options for spontaneous bacterial peritonitis? - S. aureus/coagulase negative staphylococci (risk for MRSA)
consider the addition of one of the following: vancomycin, linezolid, daptomycin
What are recommended treatment options for spontaneous bacterial peritonitis? - anaerobic coverage
beta-lactam/beta-lactamse inhibitor (ceftriaxone, cefepime), carbapenem, add metronidazole
What is the treatment duration for spontaneous bacterial peritonitis?
SBP in patient with cirrhosis and ascites
▪5-7 days
▪Secondary prophylaxis recommended after treatment completed
⎻ Example options – TMP/SMX DS PO once daily or ciprofloxacin 500 mg PO once daily
Peritonitis in patient undergoing CAPD
▪May require removal of peritoneal dialysis catheter and transition to hemodialysis ▪Intraperitoneal administration of antibiotic(s) preferred
▪14-21 days
What are the causative pathogens of intra-abdominal infections for secondary peritonitis?
E. coli!!
bacteroides species (B. fragilis most common)
polymicrobial
staph aureus and psuedomonas aeruginosa possible, but less common
What makes intra-abdominal infections unique?
Multiple organ systems affected
▪GI tract – bowel paralysis→abdominal distention
▪Cardiovascular – fluid shifts→hypotension, tachycardia, vasoconstriction
▪Respiratory – hypoxemia
▪Renal – decreased renal perfusion→renal failure
Bacterial synergy
▪Enterobacterales (e.g., E. coli) create optimal environment for anaerobic bacteria
▪Anaerobes cause abscess formation and have several virulence factors
What are the clinical presentations of intra-abdominal infections (secondary peritonitis)?
Signs/symptoms
▪Abdominal pain and distention
▪Nausea and vomiting
▪Fever +/- chills
▪Loss of appetite
▪Inability to pass flatus and/or feces
Physical exam findings/vital signs
▪Tachypnea, tachycardia
▪Hypotension
▪Significant abdominal tenderness
▪Rigidity of abdominal wall
▪Reduced or absent bowel sounds
What is the diagnostic work-up of intra-abdominal infections (secondary peritonitis)?
signs + symptoms of IAI PLUS imaging (CT scan or X-ray)
What are the treatment considerations for intra-abdominal infections (secondary peritonitis)?
source control + antimicrobial therapy
What is source control for intra-abdominal infections (secondary peritonitis)?
Examples of Source Control Procedures
* Repair perforations
* Resection of infected organs/tissue
* Removal of foreign material
* Drain purulent collections –> Important to obtain cultures
What is the empiric antibiotic selection for intra-abdominal infections (secondary peritonitis)?
- Select agent or combination of agents with high likelihood to cover common organisms – Must look at the local antibiogram!
- Consider if Enterococci coverage is necessary
- Consider if antifungal coverage is necessary
- Select agent or combination of agents with high likelihood to cover common organisms – Must look at the local antibiogram!
agents generally not recommended if resistance rates exceed 10-20%
- Consider if Enterococci coverage is necessary
▪Not necessary for mild-moderate severity community-acquired IAI
▪Recommended for (1) high severity IAI, (2) history of recent cephalosporin use, (3) immunocompromised, (4) biliary source of infection, (5) history of valvular heart disease, and/or (6) prosthetic intravascular material
- Consider if antifungal coverage is necessary
▪Empiric coverage for Candida species unnecessary – only add if isolated in culture ▪May consider if patient not improving on appropriate antibiotic therapy
▪May consider with esophageal perforation
What are the empiric antibiotic regimens for intra-abdominal infections (secondary peritonitis)? - community-acquired mild-moderate severity
Ceftriaxone 1-2 g IV Q24H + Metronidazole 500 mg IV/PO Q8-12H
Cefazolin 2 g IV Q8H + Metronidazole 500 mg IV/PO Q8-12H
Ciprofloxacin 400 mg IV Q8-12H + Metronidazole 500 mg IV/PO Q8-12H
Levofloxacin 750 mg IV Q24H + Metronidazole 500 mg IV/PO Q8-12H
Cefoxitin 2 g IV Q6H
Ertapenem 1 g IV Q24H
Tigecycline 50 mg IV Q12h
What are the empiric antibiotic regimens for intra-abdominal infections (secondary peritonitis)? - community-acquired high severity and healthcare-associated
Piperacillin/tazobactam 3.375-4.5 g IV Q6H
Meropenem 1 g IV Q8H
Cefepime 1-2 g IV Q8H + Metronidazole 500 mg IV/PO Q8-12H
Ciprofloxacin 400 mg IV Q8-12H + Metronidazole 500 mg IV/PO Q8-12H
Levofloxacin 750 mg IV Q24H + Metronidazole 500 mg IV/PO Q8-12H
What are the empiric antibiotic regimens for intra-abdominal infections (secondary peritonitis)? - candida albicans on culture
Fluconazole 200-400 mg IV/PO Q24H
What are the empiric antibiotic regimens for intra-abdominal infections (secondary peritonitis)? - candida species other than candida albicans on culture
Micafungin 100 mg IV Q24H
What is not recommended empirically for intra-abdominal infections?
Ampicillin/sulbactam not recommended empirically due to E. coli resistance
What are pathogen-directed regimens for intra-abdominal infections (secondary peritonitis)?
▪Acceptable to de-escalate the empiric antibiotic regimen once culture results are available
Note about anaerobic bacteria
▪More difficult to isolate in culture
▪Common to maintain anaerobic coverage even if culture does not isolate anaerobic bacteria
What are the oral antibiotic regimens for intra-abdominal infections (secondary peritonitis)?
▪Generally, acceptable to transition to oral antibiotic regimen once clinical stability is achieved
Common oral antibiotic regimens
▪Amoxicillin/clavulanate 875/125 mg PO Q8-12H
▪Cefpodoxime 400 mg PO Q12H + Metronidazole 500 mg PO Q8-12H
▪Cephalexin 1000 mg PO Q6H + Metronidazole 500 mg PO Q8-12H
▪Cefadroxil 1000 mg PO Q12H + Metronidazole 500 mg PO Q8-12H
▪Ciprofloxacin 500-750 mg PO Q12H + Metronidazole 500 mg PO Q8-12H
▪Levofloxacin 750 mg PO Q24H + Metronidazole 500 mg PO Q8-12H
▪TMP/SMX DS 1-2 tabs PO Q12H + Metronidazole 500 mg PO Q8-12H
What is the treatment duration for intra-abdominal infections (secondary peritonitis)?
General treatment duration: 4-7 days after source control
Diverticulitis: Uncomplicated – antibiotic not needed; Moderate/severe – 5-10 days
Appendicitis without perforation, abscess, or peritonitis: 24 hours
Cholecystitis without perforation: 24 hours
Bowel injuries repaired within 12 hours: 24 hours
Difficult to determine when source controlled is achieved in complicated infections
