To investigate the clinical efficacy and safety of the novel β-lactam/β-lactamase inhibitor combination, sulbactam-durlobactam, in the salvage treatment of severe pneumonia caused by Hypervirulent Klebsiella pneumoniae (hvKP) complicated by a secondary infection of Carbapenem-Resistant Acinetobacter baumannii (CRAB). This study also reviews relevant literature to enhance the clinical understanding, diagnosis, and management of such complex, life-threatening co-infections.

A comprehensive retrospective analysis was conducted on the clinical data of a critically ill 37-year-old male patient admitted to our hospital in 2025. The patient suffered from severe hvKP pneumonia complicated by a secondary CRAB infection. We systematically collected and evaluated the patient′s epidemiological history, dynamic clinical manifestations, and comprehensive laboratory tests (including detailed inflammatory markers, blood gas analysis, and metagenomic next-generation sequencing [mNGS]). High-resolution chest computed tomography (CT) imaging and the complete clinical treatment course-encompassing multidisciplinary antimicrobial regimen adjustments, surgical debridement, and mechanical ventilation-were thoroughly reviewed. Furthermore, a rigorous literature review was performed to summarize the pathogenic mechanisms, infection control measures, and salvage treatment strategies for this dual critical infection.

The patient initially presented with a perianal soft tissue infection that rapidly progressed to septic shock, acute respiratory failure, and diabetic ketoacidosis. Initial vital signs showed a temperature of 39.2 ℃. Laboratory findings revealed a white blood cell count of 6.8×10⁹/L (86.4% neutrophils), C-reactive protein of 284.49 mg/L, procalcitonin of 26.3 ng/mL and IL-6>5 000 pg/ml. On day 2, mNGS of blood and deep sputum identified hvKP (454 and 154, 161 sequences, respectively). By day 7, chest CT demonstrated new bilateral pneumothoraces and multiple cavitary consolidations, while bronchoalveolar lavage fluid confirmed a secondary CRAB infection (colony count 4+ ). Despite an initial 12-day aggressive empirical regimen of meropenem combined with omadacycline and polymyxin B, the patient maintained a high fever and copious pink frothy sputum; cultures persistently grew CRAB (3+ ) and hvKP (2+ ). The treatment regimen was subsequently adjusted to meropenem (1 g q 6 h) combined with sulbactam-durlobactam (2 g q 6 h). Following this targeted intervention, the patient′s temperature normalized rapidly, sputum volume decreased, and oxygenation improved significantly. After sequential therapy with polymyxin B and sulbactam, mechanical ventilation was successfully discontinued on day 41, and sputum cultures converted to negative for CRAB. By day 55, chest CT showed substantial absorption of the bilateral pneumothoraces and pulmonary exudates, allowing for discharge. No significant hepatic, renal, or neurological toxicities were observed during the extended treatment period.

hvKP infections are characterized by acute onset and aggressive systemic dissemination. Patients with prolonged exposure to broad-spectrum antibiotics and invasive procedures are highly susceptible to secondary CRAB infections, which significantly increase mortality. Early diagnostic integration of mNGS and aggressive surgical source control for primary foci are indispensable. Sulbactam-durlobactam demonstrated qualified microbiological clearance and clinical efficacy with a favorable safety profile in this refractory CRAB infection, succeeding where traditional multidrug regimens failed. It represents a vital salvage therapeutic strategy for critical drug-resistant infections.