Severe pneumonia due to Cupriavidus gilardii in a critically ill patient: a case report highlighting therapeutic dilemmas and the imperative for standardized antimicrobial guidance

<i>Cupriavidus gilardii</i> is a rare environmental Gram-negative bacillus that has increasingly been recognized as an opportunistic pathogen in recent years. Clinical management of infections caused by this microorganism remains challenging due to difficulties in identification and the lack of standardized guidelines for antimicrobial susceptibility testing (AST). This article reports the case of a 75-year-old male with severe pneumonia and multiple comorbidities. <i>Cupriavidus gilardii</i> meeting the quality standards was identified in both bronchoalveolar lavage fluid (BALF) and sputum cultures. However, conventional AST could not be performed on this rare isolation. In the absence of susceptibility data, initial empirical therapy consisted of meropenem combined with amphotericin B cholesteryl sulfate complex. Based on literature review and microbiological findings, the regimen was later adjusted to cefoperazone-sulbactam (Sulperazon) combined with minocycline. Targeted treatment led to marked improvement in inflammatory markers and chest imaging. However, therapy was discontinued prematurely at the family's request due to financial constraints, and the patient was transferred to a local hospital before full recovery could be achieved. This case demonstrates that <i>C. gilardii</i> can cause severe, life-threatening pneumonia in critically ill patients with multiple comorbidities, challenging its perception as a low-virulence opportunist. The absence of standardized antimicrobial susceptibility testing for this pathogen necessitated a literature-guided, multidisciplinary therapeutic approach, which ultimately led to clinical improvement. Our experience underscores the urgency of establishing standardized testing protocols and fostering multidisciplinary collaboration to guide the management of emerging, multidrug-resistant environmental pathogens like <i>C. gilardii</i>.