What is the best treatment approach for a patient with an electrical injury and a wound culture positive for Enterobacter (E.) cloacae and Pantoea agglomerans?

Treatment of Electrical Injury with Enterobacter cloacae and Pantoea agglomerans

For an electrical injury infected with Enterobacter cloacae and Pantoea agglomerans, perform urgent surgical debridement with deep tissue cultures, followed by empiric IV carbapenem therapy (meropenem or imipenem), avoiding third-generation cephalosporins which are ineffective against E. cloacae. 1, 2

Immediate Surgical Management

Urgent surgical consultation for sharp debridement is mandatory for electrical injuries with confirmed infection, as these wounds require removal of necrotic tissue and mechanical reduction of pathogen burden. 1

• Perform deep irrigation of the wound to remove foreign bodies and pathogens, but avoid high-pressure irrigation as this spreads bacteria into deeper tissue layers. 1
• Obtain deep intraoperative tissue cultures (not swabs) during debridement before initiating antibiotics, as this provides the most accurate microbiological identification. 1
• Electrical burns create sterile wounds initially but become rapidly colonized, typically by Gram-negative bacteria within one week of injury. 1
• Expect polymicrobial infection in burn wounds, requiring broad-spectrum coverage. 1

Empiric Antibiotic Selection

Start meropenem or imipenem immediately after obtaining cultures, as these are the recommended agents for E. cloacae infections. 2

Critical Antibiotic Considerations for E. cloacae:

• Avoid first-, second-, and third-generation cephalosporins entirely - they are ineffective against Enterobacter infections due to chromosomally-induced AmpC β-lactamase. 2, 3
• Fourth-generation cephalosporins (cefepime) can only be used if ESBL is definitively absent by molecular testing. 2, 4
• Ceftazidime has FDA approval for skin and soft tissue infections caused by Enterobacter species but should be reserved for carbapenem-resistant cases. 5

Specific Dosing Recommendations:

• Meropenem or imipenem at standard dosing for complicated skin/soft tissue infections 2
• If carbapenem resistance is confirmed: meropenem-vaborbactam 4 g IV q8h or imipenem-cilastatin-relebactam 1.25 g IV q6h 2
• Alternative for carbapenem-resistant cases: ceftazidime-avibactam 2.5 g IV q8h 2

Management of Pantoea agglomerans Component

Pantoea agglomerans is a plant-associated bacterium that typically enters through penetrating plant material injuries, causing opportunistic infections particularly in immunocompromised patients. 6, 7

• P. agglomerans responds well to appropriate antibiotics even in immunocompromised hosts, with favorable outcomes reported. 7
• This organism commonly causes septic arthritis, synovitis, and soft tissue infections following plant material contamination. 6, 8
• Search carefully for retained plant fragments or foreign bodies during debridement, as persistent infection often indicates retained vegetal material. 8
• The carbapenem regimen selected for E. cloacae will provide adequate coverage for P. agglomerans. 7

Duration and Monitoring

• Antibiotic therapy duration should be 43-57 days based on battlefield trauma data showing E. cloacae infections require longer treatment courses than other bacterial infections. 3
• Expect multiple operating room visits (median of 5) for serial debridements. 3
• Monitor for development of resistance, though serial isolation studies show resistance does not typically develop during treatment despite AmpC-inducing antibiotic exposure. 3
• Adjust antibiotic dosing for altered pharmacokinetics in burn patients to maximize efficacy. 1

Key Pitfalls to Avoid

Do not use third-generation cephalosporins (ceftriaxone, ceftazidime as monotherapy) as empiric therapy - this is the most common error and leads to treatment failure due to E. cloacae's chromosomal AmpC β-lactamase. 2, 3

• Do not rely on wound swabs - they are imprecise and miss tissue-invasive bacteria; obtain deep tissue biopsies during debridement. 1
• Do not delay surgical debridement - early excision substantially decreases invasive burn wound infection incidence. 1
• Do not assume superficial wound healing indicates infection resolution - assess for deep tissue involvement and retained foreign material. 8
• Do not use prophylactic antibiotics alone without source control through debridement. 1