Gentamicin as Monotherapy for Peritoneal Peritonitis
Gentamicin should NOT be used as monotherapy for peritoneal peritonitis because it lacks anaerobic coverage and must be combined with metronidazole or another agent providing anaerobic activity. 1
Why Monotherapy is Inadequate
Aminoglycosides, including gentamicin, have no activity against anaerobic bacteria, which are common pathogens in peritoneal infections, making combination therapy mandatory 1
The World Society of Emergency Surgery explicitly states that aminoglycosides are not recommended for routine empiric treatment of community-acquired intra-abdominal infections in adults, and should be reserved only for specific scenarios such as documented beta-lactam allergies or suspected multidrug-resistant gram-negative bacteria 1
The FDA label for gentamicin indicates that when anaerobic organisms are suspected as etiologic agents, other suitable antimicrobial therapy must be used in conjunction with gentamicin 2
Appropriate Use of Gentamicin in Peritonitis
For Peritoneal Dialysis-Associated Peritonitis:
Gentamicin is appropriately used in combination with vancomycin as empirical therapy for PD peritonitis, with this regimen showing high efficacy and no increase in antimicrobial resistance over 5-year surveillance 3
Standard intraperitoneal dosing is 40 mg/2L in the overnight bag as a single daily dose for PD peritonitis, with treatment success rates of 74-80% when combined with appropriate gram-positive coverage 4
Cephazolin plus gentamicin represents an effective non-vancomycin alternative for empirical PD peritonitis treatment, showing similar efficacy to vancomycin-based protocols 5
For Secondary Peritonitis (Non-PD):
Gentamicin must always be combined with anaerobic coverage (metronidazole) or used as part of a broader regimen that includes agents active against anaerobes 1
Third-generation cephalosporins or carbapenems are preferred over aminoglycoside-based regimens for routine community-acquired intra-abdominal infections due to better safety profiles and broader coverage 1
Critical Safety Considerations
Aminoglycosides should be avoided in patients with residual renal function due to nephrotoxicity risk, which is particularly important in PD patients where preserving residual renal function significantly impacts outcomes 6
Therapeutic drug monitoring is mandatory, with target trough concentrations <1-2 mcg/mL to prevent nephrotoxicity and ototoxicity 1, 2
Treatment duration should be limited to 48-96 hours without culture confirmation of gram-negative infection requiring aminoglycoside coverage, with de-escalation based on culture results 1
Common Pitfalls to Avoid
Never assume gentamicin monotherapy provides adequate coverage for mixed aerobic-anaerobic infections typical of peritonitis 1
Do not use aminoglycosides for pancreatic infections, as they fail to achieve adequate tissue penetration at standard IV doses 1
Avoid prolonged courses without monitoring, as gentamicin accumulates in patients with impaired renal function and can cause irreversible ototoxicity 2