Peritonitis

Peritonitis aka intra-abdominal infection

• Microbial contamination of the peritoneal cavity

• inflammation of the serosal membrane that lines the abdominal cavity and the organs contained therein

• may be infectious or sterile

Primary microbial peritonitis

• microbes invade the normally sterile confines of the peritoneal cavity via hematogenous dissemination from a distant source of infection or direct inoculation

• invariably monomicrobial and rarely require surgical intervention

Primary microbial peritonitis• Physical examination

– diffuse tenderness and guarding without localized findings• CBC

– presence of more than 100 WBCs/mL• Imaging study

– absence of pneumoperitoneum• Gram’s stain (fluid obtained via paracentesis)

– microbes with a single morphology• Diagnosis:

– established based on identification of risk factors (ascites, individuals who are being treated for renal failure via peritoneal dialysis)

Primary microbial peritonitis

• Treatment – administration of an antibiotic to which the

organism is sensitive often 14 to 21 days of therapy are required.

– Removal of indwelling devices (e.g., a peritoneal dialysis catheter or a peritoneovenous shunt) may be required for effective therapy of recurrent infections.

Secondary microbial peritonitis

• occurs subsequent to contamination of the peritoneal cavity due to perforation or severe inflammation and infection of an intra-abdominal organ

• e.g. appendicitis, perforation of any portion of the gastrointestinal tract, or diverticulitis

Secondary microbial peritonitis

• in most patients the precise diagnosis cannot be established until exploratory laparotomy is performed

• most morbid form of this disease process is colonic perforation, due to the large number of microbes presen

Effective Therapy

• source control to resect or repair the diseased organ

• débridement of necrotic, infected tissue and debris

• administration of antimicrobial agents directed against aerobes and anaerobes

• Effective source control and antibiotic therapy is associated with low failure rates and a mortality rate of approximately 5% to 6%

• inability to control the source of infection is associated with mortality greater than 40%

Tertiary (persistent) peritonitis• develops more frequently in

immunocompromised patients and in persons with significant preexisting comorbid conditions

• Microbes such as Enterococcus faecalis and faecium, Staphylococcus epidermidis, Candida albicans, and Pseudomonas aeruginosa commonly are identified, typically in combination, and their presence may be due to their lack of responsiveness to the initial antibiotic regimen, coupled with diminished activity of host defenses

• even with effective antimicrobial agent therapy, this disease process is associated with mortality rates in excess of 50%.

Tertiary (persistent) peritonitis

• Diagnosis– Intraabdominal abscesses can be effectively diagnosed via

abdominal computed tomographic (CT) imaging techniques and drained percutaneously.

• Surgical intervention– reserved for those individuals who harbor multiple abscesses,

those with abscesses in proximity to vital structures such that percutaneous drainage would be hazardous, and those in whom an ongoing source of contamination (e.g., enteric leak) is identified.

• Antimicrobial agent therapy – necessity not established

• Catheter drainage– precise guidelines that dictate duration are not established

• A short course (3 to 7 days) of antibiotics that possess aerobic and anaerobic activity seems reasonable

• Most practitioners leave the drainage catheter in situ until– it is clear that cavity collapse has occurred– output is less than 10 to 20 mL/d– no evidence of an ongoing source of

contamination is present– patient’s clinical condition has improved

Common Causes of Secondary Peritonitis

Microbial Flora of Secondary Peritonitis

Microbiology of Primary, Secondary, and Tertiary Peritonitis