Intra-abdominal Infections Flashcards
(53 cards)
By definition an IAI is:
A diverse set of diseases
Peritoneal inflammation in response to microorganisms with associated purulence in the peritoneal cavity
IAI classifications
Primary organ infected
Uncomplicated vs. complicated
Uncomplicated-infection contained in single organ (e.g., stomach) without anatomical disruption
Setting of acquisition
(CA-IAI) Community-acquired intra-abdominal infection
(HA-IAI) Healthcare- or hospital acquired-intra-abdominal infection
Severity of illness and risk
What makes an IAI complicated?
Extends beyond source organ into the peritoneal space
Peritoneal inflammation with:
Localized peritonitis –> abscess
Diffuse peritonitis
Intra-abdominal abscess
Purulent collection of fluid
Contains:
- Necrotic debris
- Bacteria
- Inflammatory cells
- Fibrous capsule
Walled off by inflammatory cells and adjacent organs
Hard for antibiotics to penetrate
Ideal environment for anaerobes
Tertiary peritonitis
Persistent or recurrent at least 48 hours after appropriate management of primary or secondary peritonitis
Associated with low virulence organisms in critically ill or immunosuppressed
Secondary peritonitis
Spread from another organ resulting in focal disease in the abdomen
Polymicrobial
Primary peritonitis
Infection of peritoneal cavity without an evident source in the abdomen
Spontaneous bacterial peritonitis
Monomicrobial
Primary peritonitis
Occurs in children and adults
10-30% of alcoholic cirrhotic patients (SBP)
Peritoneal dialysis patients average 1 episode
Secondary peritonitis
Account for 80-90% of intra-abdominal infections
Appendicitis is most common
Primary peritonitis
Bacteria enter via:
Bloodstream or the lymphatic system via gut transmigration
Indwelling peritoneal dialysis catheter
Fallopian tubes in females
Secondary peritonitis
Bacteria enter via:
Perforation of GI or female genital tracts after
Disease process
Trauma
Introduction during surgery
Contamination
Anastomotic leak
Which of the following DOES NOT represent a common etiology of primary peritonitis?
A.) Cirrhosis with ascites B.) Trauma C.) Peritoneal dialysis D.) Nephrotic syndrome E.) Spontaneous bacterial peritonitis
B.) Trauma
Microbiology of primary peritonitis
Normally monomicrobial
Cirrhotic ascites
E. coli (most common)
Other: Klebsiella spp., S. pneumoniae, and enterococci
Peritoneal dialysis
Staphylococci
Streptococci
E. coli
Klebsiella spp.
Pseudomonas spp.
Microbiology of cIAI
Most common pathogens (Greater than 10%)
Facultative and aerobic gram-negative:
Gram-positive aerobic cocci:
Anaerobic:
Facultative and aerobic gram-negative:
Escherichia coli
Klebsiella species
Pseudomonas aeruginosa
Gram-positive aerobic cocci:
Streptococcus species
Enterococcus faecalis
Anaerobic: Bacteroides fragilis Other Bacteroides species Clostridium species Prevotella species Peptostreptococcus species Eubacterium species
Which of the following DOES NOT represent a common pathogen (>10%) isolated from complicated IAIs?
A.) Escherichia coli B.) Streptococcus species C.) Bacteroides fragilis D.) Staphylococcus aureus E.) Klebsiella species
D.) Staphylococcus aureus
Clinical presentation of primary and secondary peritonitis
Voluntary to involuntary abdominal guarding, abdominal tenderness and distension, faint bowel sounds.
Clinical presentation of primary peritonitis laboratory tests
Mildly elevated WBC, elevated fluid WBC (e.g., >250 leukocytes/mm3 in ascitic fluid)
Clinical presentation of secondary peritonitis laboratory tests
Leukocytosis, elevated hematocrit and BUN d/t dehydration, progresses to acidosis from vomiting
Diagnosing peritonitis
Ultrasound and CT
CT more difinitive
Fluid workup in primary peritonitis
>250 PMN/mm3 (ascitic) in SBP
>100/µL white cell count (dialysis effluent) in peritoneal dialysis catheter infection
Treatment of primary peritonitis
Cirrhotic ascites-SBP
Primary treatment:
Cefotaxime or ceftriaxone (preferred)
Duration of therapy: 5 days
Secondary prophylaxis
Ciprofloxacin, trimethoprim-sulfamethoxazole
Peritoneal dialysis
Primary treatment:
vancomycin + 3rd generation cephalosporin or aminoglycoside
Overall approach to IAI
NON-PHARM
SOURCE CONTROL
Evaluate microbial agents
Source control for IAI
“Considered fundamental to the treatment of most patients with IAI”
Undertake within 24 hours of diagnosis
Use least invasive procedure
Percutaneous drainage
Antimicrobial approach
Patient risk category
Setting of acquisition
Previous resistance documented
Local resistance patterns
In general should cover:
Typical Gram-negative enterics
Gram-positive cocci
Obligate anaerobes
Healthcare- or Hospital-Acquired-IAI definition
Infection developing greater than 48 hours after initial source control
Hospitalized for greater than 48 hours during current admission or within the previous 90 days
Residence in a skilled nursing or other long-term care facility within the previous 30 days
Home infusion therapy, home wound care, or dialysis within the preceding 30 days
Use of broad-spectrum antimicrobial therapy for 5 d or more during the preceding 90 days
