Intraabdominal infections antimicrobials

Cultures of secondary intraabdominal infection sites generally are not useful for directing antimicrobial therapy. Treatment generally is initiated on a presumptive or empirical basis. 

Antimicrobial regimens for secondary intraabdominal infections should include coverage for enteric gram-negative bacilli and anaerobes. Antimicrobial agents that may be used... 

The duration of antimicrobial treatment should be for a total of 5 to 7 days for most intraabdominal infections. 

The treatment of intraabdominal infection most often requires the coordinated use of three major modalities (1) prompt drainage, (2) support of vital functions, and (3) appropriate antimicrobial therapy to treat infection not eradicated by surgery. Antimicrobials are an important adjunct to drainage procedures in the treatment of secondary intraabdominal infections however, the use of antimicrobial agents without surgical intervention usually is inadequate. For most cases of primary peritonitis, drainage procedures may not be required, and antimicrobial agents become the mainstay of therapy. 

Many studies have been conducted evaluating or comparing the effectiveness of antimicrobials for treatment of intraabdominal infections. Substantial differences in patient outcomes from treatment with a variety of agents generally have not been demonstrated. 

Important findings from the last 20 years of clinical trials regarding selection of antimicrobials for intraabdominal infections are... 

Five to seven days of antimicrobial treatment are sufficient for most intraabdominal infections of mild to moderate severity. 

TABLE 74-3. Guidelines for Initial Antimicrobial Agents for Intraabdominal Infections... 

If symptoms do not improve, the patient should be evaluated for persistent infection. There are many reasons for poor patient outcome with intraabdominal infection improper antimicrobial selection is only one. The patient maybe immunocompromised, which decreases the likelihood of successful outcome with any regimen. It is impossible for antimicrobials to compensate for a nonfunctioning immune system. There may be surgical reasons for poor patient outcome. Failure to identify all intraabdominal foci of infection or leaks from a GI anastomosis may cause continued intraabdominal infection. Even when intraabdominal infection is controlled, accompanying organ system failure, most often renal or respiratory, may lead to patient demise. 

Treatment regimens for intraabdominal infection can be judged as successful if the patient recovers from the infection without recurrent peritonitis or intraabdominal abscess and without the need for additional antimicrobials. A regimen can be considered unsuccessful if a significant adverse drug reaction occurs, reoperation or percutaneous drainage is necessary, or patient improvement is delayed beyond 1 or 2 weeks. 

Mazuski JE, Sawyer RG, Nathens AB, et al. The Surgical Infection Society guidelines on antimicrobial therapy for intraabdominal infections An executive summary. Surg Infect 2002 3 161-174. 

The three major modalities for the treatment of intraabdominal infection are prompt surgical drainage, support of vital functions, and appropriate antimicrobial therapy to treat infection not removed by surgery. 

Antimicrobials are an important adjunct to drainage procedures in the treatment of intraabdominal infections however, the use of antimicrobial agents without surgical intervention is usually inadequate. For some specific situations (e.g., most cases of primary peritonitis), drainage procedures... 

An empiric antimicrobial regimen should be started as soon as the presence of intraabdominal infection is suspected on the basis of likely pathogens. 

Table 42-4 presents recommended and alternative regimens for selected situations. These are general guidelines, not rules, because there are many factors that cannot be incorporated into such a table. Guidelines for initial antimicrobial treatment of specific intraabdominal infections are presented in Table 42-5. 

For established intraabdominal infections, most patients are adequately treated with 5 to 7 days of antimicrobial therapy. 

Antimicrobial regimens for secondary intraabdominal infections should include coverage for enteric gram-negative bacilli and anaerobes. Antimicrobials that may be used for the treatment of secondary intraabdominal infections include (a) a /3-lactam// -lactamase inhibitor combination, (b) a carbapenem, (c) quinolone plus metronidazole, or an aminoglycoside plus clindamycin (or metronidazole). 

Patients treated for intraabdominal infections should be assessed for the occurrence of drug-related adverse effects, particularly hypersensitivity reactions (/ -lactam antimicrobials), diarrhea (most agents), fungal infections (most agents), and nephrotoxicity (aminoglycosides). 

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