Clinical Scorecard: Effective Administration of Outpatient Parenteral Antimicrobial Therapy (OPAT) with Aztreonam–Avibactam in a Pediatric Patient with Infectious Pseudoarthrosis Due to NDM-Producing Klebsiella pneumoniae and Pseudomonas aeruginosa

At a Glance

Key Highlights

• A 9-year-old girl received off-label aztreonam-avibactam for infectious pseudoarthrosis.

• Bone cultures grew P aeruginosa and ESBL- and NDM-producing K pneumoniae; the K pneumoniae isolate was susceptible only to gentamicin and aztreonam-avibactam.

• Management combined orthopedic surgery, pediatric infectious disease care, pharmacy support, and targeted antimicrobial therapy.

• Caregivers were trained in home administration, intravenous-line care, device replacement, and recognition of warning signs.

• A transient alanine aminotransferase elevation prompted treatment interruption; therapy was restarted after liver enzymes normalized.

• Two months after completing treatment, the patient had no signs or symptoms of persistent or recurrent infection.

Guideline-Based Recommendations

Diagnosis

• Computed tomography demonstrated distal right tibial nonunion.

• Infectious pseudoarthrosis was confirmed through intraoperative bone cultures, organism identification, resistance-mechanism testing, and antimicrobial susceptibility testing.

• This single case did not establish diagnostic guidelines for pediatric infectious pseudoarthrosis.

Management

• Aztreonam-avibactam was used off-label because therapeutic alternatives for the NDM-producing isolate were limited.

• The initial inpatient regimen provided 155 mg/kg/day of the aztreonam component, administered every 6 hours as 3-hour intravenous infusions.

• Repeat surgical intervention was undertaken to address tibial malunion and persistent bone infection.

• This case does not support routine aztreonam-avibactam use for all pediatric multidrug-resistant infections.

Monitoring & Follow-up

• Monitor clinical status, intravenous-line care, infusion-device use, and laboratory findings during OPAT.

• Liver enzymes require careful monitoring because a transient alanine aminotransferase elevation occurred during treatment.

• The patient was assessed 2 months after therapy, but longer-term outcomes were not available.

Risks

• Aztreonam-avibactam is not approved for pediatric use, and its pediatric safety profile remains undefined.

• Suspected hepatotoxicity required temporary treatment interruption.

• The absence of therapeutic drug monitoring and the short follow-up limited assessment of drug exposure and long-term outcomes.

Patient & Prescribing Data

The patient was a 9-year-old girl weighing 19.3 kg with war-related polytrauma and infectious pseudoarthrosis of the right distal tibia.

Inpatient aztreonam-avibactam was dosed at 155 mg/kg/day based on the aztreonam component. For home treatment, two elastomeric pumps were supplied daily; each contained 1,500 mg of aztreonam and 500 mg of avibactam in 60 mL of normal saline and infused over 12 hours at 5 mL/h. The total treatment course was 6 weeks.

Clinical Best Practices

• Use multidisciplinary management for complex osteoarticular infections with limited antimicrobial options.

• Base targeted therapy on bone cultures, resistance-mechanism confirmation, and susceptibility testing.

• Provide caregivers with detailed education on administration, line care, warning signs, and device replacement.

• Confirm drug stability and use pharmacy-prepared individualized doses for home infusion.

• Monitor for hepatotoxicity and reassess the risks and benefits before restarting therapy after an abnormality.

• Interpret this experience cautiously because it involved one patient and short-term follow-up.

Related Resources & Content

1. Successful Use of Outpatient Parenteral Antimicrobial Therapy (OPAT) Aztreonam-Avibactam in a Pediatric Case of an Infectious Pseudoarthrosis Caused by NDM-Producing Klebsiella pneumoniae and Pseudomonas aeruginosa — Bosch-Peligero M, Codina-Jimenez C, Chaguaceda Galisteo C, et al. International Journal of Infectious Diseases. 2026;170:108840. doi:10.1016/j.ijid.2026.108840.

2. Infectious Diseases Society of America 2024 Guidance on the Treatment of Antimicrobial-Resistant Gram-Negative Infections — Tamma PD, Heil EL, Justo JA, Mathers AJ, Satlin MJ, Bonomo RA. Clinical Infectious Diseases. 2024:ciae403. doi:10.1093/cid/ciae403.

3. Delivery, Setting and Outcomes of Paediatric Outpatient Parenteral Antimicrobial Therapy: A Scoping Review — BMJ Open. 2018;8:e021603. doi:10.1136/bmjopen-2018-021603.

4. Pediatric aztreonam-avibactam trial — ClinicalTrials.gov identifier: NCT05639647.

5. Pediatric aztreonam-avibactam trial — ClinicalTrials.gov identifier: NCT06462235.