Intra-abdominal Infections (IAI) - Lecture Notes - October 26, 2023

Intra-abdominal Infections (IAI) Dhara Surati, PharmD, BCPS University of Houston College of Pharmacy PHAR 5337: ID 1 Module October 26, 2023 [email protected] Objectives • Compare and contrast primary vs. secondary peritonitis • Select common organisms involved in an intraabdominal infection...

Intra-abdominal Infections (IAI) Dhara Surati, PharmD, BCPS University of Houston College of Pharmacy PHAR 5337: ID 1 Module October 26, 2023 [email protected] Objectives • Compare and contrast primary vs. secondary peritonitis • Select common organisms involved in an intraabdominal infection (IAI) • Select clinical presentation, diagnostic tests, and therapeutic goals associated with IAI • Choose an appropriate non-pharmacologic intervention for a complicated IAI • Recommend an appropriate empiric antimicrobial regimen for a complicated IAI • Choose an efficacy and safety monitoring plan for patients with a complicated IAI Main References • Reference 1: Textbook: Chapter 137: Gross AE, Wagner JL, Olsen KM. Intra-Abdominal Infections. In: DiPiro JT, Yee GC, Michael Posey LL, Haines ST, Nolin TD, Ellingrod VL. eds. DiPiro: Pharmacotherapy A Pathophysiologic Approach, 12e. McGraw Hill; 2021. • Reference 2: Guidelines: Solomkin JS et al. CID. 2010;50:133-64. (Archived) – www.idsociety.org (Practice guidelines) – Update in progress Format: • Slide deck • Interactive/active learning component Intra-abdominal infections Intra-abdominal infections within Peritoneal cavity Reference 1 retro-peritoneal space Peritoneal cavity Stomach, jejunem, ileum, cecum, appendix, transverse and sigmoid colon, liver, gallbladder and spleen Retroperitoneal space Ascending and descending colon, duodenum, pancreas, kidneys, and adrenals Classification of IAI • Community- vs. healthcare-associated • Uncomplicated vs. complicated • Presence and source of peritonitis Reference 1; 2 Community vs. healthcare-associated IAI • Community associated / early onset hospital – Early onset hospital: < 7 days • Late healthcare associated – ≥ 7 days Blot S, et al. Drugs 2012. 16; 72:e17-32 Uncomplicated vs. Complicated IAI Uncomplicated • Within visceral structures Reference 1 Complicated • Extend beyond one organ • Peritonitis / abscess Peritonitis Acute inflammatory response of peritoneal lining Caused by microorganisms, chemicals, irradiation or foreignbody injury Reference 1 Types of peritonitis Peritonitis Primary Reference 1 Secondary Tertiary Primary peritonitis Also known as: spontaneous bacterial peritonitis • Causes: Cirrhosis with ascites Reference 1 Peritoneal dialysis Microbiology of primary peritonitis Common skin organisms: __________, ___________ Other pathogens: E. coli Klebsiella Pseudomonas Usually single organism Reference 1 Secondary peritonitis • Caused by an intra-abdominal source • Examples: Appendicitis Pancreatitis Cholecystitis Reference 1 Microbiology of secondary peritonitis polymicrobial Reference 1 Microbiology of secondary peritonitis Gram-negative bacteria Escherichia coli Enterobacter Klebsiella Proteus Gram-positive bacteria Enterococci Streptococci Staphylococci Anaerobic bacteria Bacteroides Clostridium Fungi Reference 1: Based on table 92-3 Overview of assessment – secondary peritonitis Symptoms/signs Vitals/Physical assessment Laboratory findings Other • Abdominal pain • Nausea • Vomiting • Vitals: • Temp • BP • HR • RR Elevated: • SCr • BUN • WBC Change: • ABG Imaging results • Abdominal exam – unreliable • Monitor urine output 17 Complications of peritonitis • • • • • Hypovolemia / hypotension/hypoalbuminemia Respiratory distress syndrome Acute renal and hepatic failure Septic shock Death Reference 1 Tertiary peritonitis • Persists OR • recurs ≥ 48 hours after adequate management of primary or secondary peritonitis Reference 1 Intra-abdominal abscess How long can it take for an abscess to form? Reference 1 Location of an abscess • Location: Peritoneal space or one of the visceral organs Likely location of an abscess: Liver Associated with: Spleen Pancreas Bacteremia, IV drug abuse Pancreatitis Reference 1 Cholecystitis, appendicitis, diverticulitis, peritonitis, trauma Clinical presentation / Imaging • Clinical signs/symptoms – Low grade fever – abdominal distention – +/- pain • Imaging is necessary for diagnosis – Ultrasound – Computed tomography (CT) – Magnetic Resonance Imaging (MRI) Reference 1 Case vignette: Assess subjective and objective info • KR, a 32-year-old female, presents in acute distress with 10/10 abdominal pain. She has been experiencing pain in her abdominal area along with several episodes of vomiting since last 18 hours. Her PMH significant for hypothyroidism and peptic ulcer disease. Her pregnancy test upon ED admission is negative. Her vital include BP 90/58 mmHg; HR 118; RR 22; Temp 102 degrees F; Weight: 110 lbs; Height: 5’ 8”. Her labs upon arrival to ED include SCr: 1.5 mg/dL (baseline SCr: 0.9 mg/dL) and WBC: 20 X 103 cells/mm3. Imaging studies reveal perforation of a peptic ulcer. She denies alcohol, illicit drug use, tobacco, and recent travel outside the US. Assess: Treatment: Complicated intra-abdominal Infection (peritonitis and abscess) • Treatment slides do not focus on primary peritonitis • Treatment slides do not focus on biliary infections Goals • • • • • Correction of underlying process Drainage of abscess Resolution of infection Prevent complications of major organ systems Minimize adverse drug effects Reference 1 Surgical interventions in secondary peritonitis/abscess • Purpose – Remove inflamed or gangrenous source – Prevent further bacterial contamination • Treatment of secondary peritonitis may include: – Patching of an ulcer – Resection of perforated colon or gangrenous small bowel • If abscess is present: – Drainage of an abscess is the KEY STEP Reference 1 Fluid resuscitation • Rapid restoration of intravascular volume • For patients with septic shock: – Aggressive fluid repletion • Without evidence of volume depletion: – IV fluid therapy Reference 1 Role of antimicrobial therapy in secondary peritonitis/abscess • Antimicrobials – as adjunct therapy • Goals: – To control bacteremia – To reduce complications – To prevent local spread • Initiate empiric therapy once suspected – Once cultures are obtained Reference 1 Empiric antimicrobial regimen Consideration: organisms Gram positive Gram negative polymicrobial anaerobes Enterococci? Nosocomial Gram negative? MRSA? Reference 2: Based on Table 2; Blot S, et al. Drugs 2012. 16; 72:e17-32 Candida? Empiric antimicrobial regimen Consideration: Severity of infection • Mild-moderate vs. • Severe Reference 2 Empiric antimicrobial regimen Consideration: Community vs. healthcare-associated • Community associated / early onset hospital – Early onset hospital: < 7 days • Late healthcare associated – ≥ 7 days Blot S, et al. Drugs 2012. 16; 72:e17-32 Initial empiric therapy: Community-associated/early onset hospital complicated IAI (in adults) Mild-to-moderate Severe Single agent Ertapenem Moxifloxacin Tigecycline Imipenem-cilastatin Meropenem Piperacillin-tazobactam Combination therapy Cefazolin Ceftriaxone Cefotaxime Ciprofloxacin* Levofloxacin* Cefepime Ceftazidime Ciprofloxacin* Levofloxacin* PLUS MTZ^ *In areas with high resistance rates, use with caution Reference 2: Based on Table 2; Blot S, et al. Drugs 2012. 16; 72:e17-32 PLUS MTZ^ MTZ^ = metronidazole Initial empiric therapy for complicated IAI: Late healthcare-associated or recent antimicrobials • Nosocomial gram negatives – P. aeruginosa – ESBL-producing Enterobacteriaceae • MRSA • Enterococci • Candida species Reference 2; Blot S, et al. Drugs 2012. 16; 72:e17-32 Based on risk factors, extensive past medical history, and recent prior hospitalizations, JP, a 60-year old male, will now be initiated on meropenem, micafungin, and linezolid due to concerns for late-healthcare associated, complicated intra-abdominal infection. For the last two weeks, JP has received cefepime and vancomycin. The switch in therapy is due to his deteriorating condition. He also has acute renal failure, currently not on hemodialysis. Allergies: NKDA Assess the antimicrobials listed: Will be initiated: For the last two weeks: Meropenem – Cefepime - Linezolid – Vancomycin - Micafungin – Antibiogram slide 1 – reference Antibiogram slide 2 - reference Antibiogram slide 3 - reference Duration of treatment • Duration – 4 – 7 days in most cases • Exception: adequate source control not achieved • Longer duration may be warranted with: References 1 and 2 Efficacy monitoring • Resolution of signs and symptoms – Improvement: 2 to 3 days – Afebrile – Stability of vital signs • Review culture and sensitivity (for definitive therapy) – Narrow therapy if possible • Difficult to do; don’t always catch all of the organisms • Observe for evidence of super-infection Reference 1 Efficacy monitoring • For pharmacokinetic changes in severely ill – Fluid overload – Organ dysfunction Safety monitoring • Safety monitoring: Dependent on antimicrobial(s) selected; please refer to appropriate reference(s) for adverse effects profile / safety monitoring parameters of individual antimicrobials Intra-abdominal Infections (IAI) Dhara Surati, PharmD, BCPS University of Houston College of Pharmacy PHAR 5337: ID 1 Module October 26, 2023 [email protected]