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<p>Carbapenem-resistant <i>Pseudomonas aeruginosa</i> (CRPA) poses growing therapeutic challenges, particularly in critically ill, immunocompromised patients. More concerning is the rapid shift in resistance mechanisms—such as from non–MBL to metallo-β-lactamase (MBL) producers—within days, which can render initial targeted therapy ineffective.&#xa0;Male in his seventies with esophageal cancer underwent chemoradiotherapy followed by dual immune checkpoint inhibitor therapy, resulting in profound immune dysfunction. After a complex esophagectomy complicated by anastomotic leakage, he developed severe pneumonia while receiving mechanical ventilation, extracorporeal membrane oxygenation (ECMO), and continuous renal replacement (CRRT). Aspergillus fumigatus was first isolated from bronchoalveolar lavage on postoperative day (POD) 4. On POD 12, CRPA with OprD loss and AmpC overexpression was subsequently isolated, as confirmed by antimicrobial susceptibility testing (AST); no other bacterial species were detected. Treatment with ceftazidime/avibactam combined with intravenous amikacin and polymyxin B, together with adjuncts inhaled tobramycin, produced only transient improvement. By POD 15, repeated culture revealed a distinct CRPA isolate producing a VIM-type MBL. Therapy was promptly switched to aztreonam (2&#xa0;g, q8h) plus ceftazidime/avibactam (2.5&#xa0;g, q8h), alongside polymyxin B (1&#xa0;million U, q12h), high-dose amikacin(15&#xa0;mg/kg), fosfomycin (4&#xa0;g, q8h), and inhaled tobramycin (300&#xa0;mg, bid), leading to clinical recovery and microbiologic clearance.&#xa0;This case underscores the need for enhanced mechanism-based surveillance of antimicrobial resistance and adaptive antimicrobial management in high-risk patients. The rapid within-host replacement and emergence of an non-MBL to MBL CRPA highlights the necessity for frequent cultures and rapid carbapenemase testing to guide timely, targeted therapy.</p>

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Case report: rapid in vivo resistance mechanism shifts in multiple carbapenem-resistant Pseudomonas aeruginosa strains after esophagectomy in an immunocompromised patient: a case report

  • 期刊论文

  • 发表日期：

    2025年12月23日

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  • Huan Tang,
  • Xinyi Liu,
  • Hai Zhang,
  • Lin Chen

摘要

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) poses growing therapeutic challenges, particularly in critically ill, immunocompromised patients. More concerning is the rapid shift in resistance mechanisms—such as from non–MBL to metallo-β-lactamase (MBL) producers—within days, which can render initial targeted therapy ineffective. Male in his seventies with esophageal cancer underwent chemoradiotherapy followed by dual immune checkpoint inhibitor therapy, resulting in profound immune dysfunction. After a complex esophagectomy complicated by anastomotic leakage, he developed severe pneumonia while receiving mechanical ventilation, extracorporeal membrane oxygenation (ECMO), and continuous renal replacement (CRRT). Aspergillus fumigatus was first isolated from bronchoalveolar lavage on postoperative day (POD) 4. On POD 12, CRPA with OprD loss and AmpC overexpression was subsequently isolated, as confirmed by antimicrobial susceptibility testing (AST); no other bacterial species were detected. Treatment with ceftazidime/avibactam combined with intravenous amikacin and polymyxin B, together with adjuncts inhaled tobramycin, produced only transient improvement. By POD 15, repeated culture revealed a distinct CRPA isolate producing a VIM-type MBL. Therapy was promptly switched to aztreonam (2 g, q8h) plus ceftazidime/avibactam (2.5 g, q8h), alongside polymyxin B (1 million U, q12h), high-dose amikacin(15 mg/kg), fosfomycin (4 g, q8h), and inhaled tobramycin (300 mg, bid), leading to clinical recovery and microbiologic clearance. This case underscores the need for enhanced mechanism-based surveillance of antimicrobial resistance and adaptive antimicrobial management in high-risk patients. The rapid within-host replacement and emergence of an non-MBL to MBL CRPA highlights the necessity for frequent cultures and rapid carbapenemase testing to guide timely, targeted therapy.