Abstract Introduction Acinetobacter species are aerobic, gram-negative coccobacilli that have become increasingly recognized as causes of hospital-acquired infection. A. baumannii remains the predominant pathogen, but rare species such as A. radioresistens are emerging. Because these organisms may harbor chromosomal carbapenemase genes (e.g., bla-OXA-23), rapid identification is essential for appropriate therapy and infection control. Case Presentation A 77-year-old man with newly diagnosed lung adenocarcinoma and hepatic metastases presented from a group home with dyspnea and hypotension. Comorbidities included COPD, dementia, and prior alcohol abuse. He was afebrile, tachypneic (31 breaths/min), hypoxic (SpO2 85% RA), and hypotensive (77/61 mm Hg). Chest radiograph showed right lower-lobe opacity; CT chest demonstrated complete opacification of the right lower lobe and multiple pulmonary nodules. Laboratory testing revealed leukocytosis (14.9 × 10³/µL), metabolic acidosis (pH 7.15, bicarbonate 10 mmol/L, lactate 18.5 mmol/L), and acute kidney injury (creatinine 2.5 mg/dL). He was intubated for acute hypoxemic respiratory failure and started empirically on vancomycin and cefepime. One of two blood cultures grew a gram-negative bacillus that was untypable by routine testing; sputum grew Klebsiella pneumoniae. VERIGENE Gram-Negative Blood Culture assay detected an Acinetobacter species without resistance markers, later identified by MALDI-TOF mass spectrometry as A. radioresistens—pan-susceptible to β-lactams, aminoglycosides, fluoroquinolones, and TMP-SMX. Targeted therapy with ampicillin-sulbactam (3 g IV q8h) was given for eight days, leading to transient hemodynamic and oxygenation improvement. The patient subsequently developed recurrent respiratory failure, and his family elected comfort-focused care; he died shortly after withdrawal of life support. Discussion Acinetobacter radioresistens is a low-virulence environmental organism but can cause severe infection in immunocompromised or critically ill hosts. Although rarely reported, bloodstream infection by this species is clinically significant, particularly given its ability to act as a silent reservoir for carbapenem-resistance genes. This case highlights the importance of advanced molecular diagnostics—such as VERIGENE microarray and MALDI-TOF—in distinguishing uncommon Acinetobacter species and guiding timely therapy. Recognition of A. radioresistens infections should prompt vigilance for nosocomial transmission and reinforce antimicrobial-stewardship measures to limit emergence of multidrug-resistant strains. This abstract is funded by: None
George et al. (Fri,) studied this question.