Ren Xiaomei, Clark R Mason, Bansah Dziedzom A, Varner Elizabeth N, Tiffany Connor R, Jaswal Kanchan, Geary John H, Todd Olivia A, Winkelman Jonathan D, Friedman Elliot S, Jarrett Riley N, Zemel Babette S, Wu Gary D, Zackular Joseph P, DePas William H, Behnsen Judith, Palmer Lauren D
Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, IL 60612, USA.
Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15227, USA.
Cell Host Microbe. 2025 Aug 13;33(8):1396-1411.e9. doi: 10.1016/j.chom.2025.07.003. Epub 2025 Aug 4.
Asymptomatic colonization is often critical for persistence of antimicrobial-resistant pathogens, such as Acinetobacter baumannii, and can increase the risk of clinical infections. However, the ecological factors shaping A. baumannii gut colonization remain unclear. We show that A. baumannii and other pathogenic Acinetobacter evolved to utilize the amino acid ornithine, a non-preferred carbon source, to compete with resident microbiota and persist in the gut in mice. A. baumannii encodes ornithine succinyltransferase (AstO) necessary for catabolizing ornithine, especially in conditions of increased microbial diversity. Supplemental dietary ornithine promotes long-term fecal shedding of A. baumannii. By contrast, supplementation of preferred carbon sources-monosodium glutamate or histidine-abolishes the requirement for ornithine catabolism. Additionally, A. baumannii gut carriage is higher in formula-fed human infants, who generally consume higher levels of protein, revealing dietary impacts on Acinetobacter colonization. Together, these results reveal that ornithine catabolism facilitates A. baumannii colonization, providing a reservoir for pathogen spread.
无症状定植对于鲍曼不动杆菌等耐抗菌性病原体的持续存在往往至关重要，并且会增加临床感染的风险。然而，塑造鲍曼不动杆菌肠道定植的生态因素仍不清楚。我们发现，鲍曼不动杆菌和其他致病性不动杆菌已进化到利用氨基酸鸟氨酸（一种非首选碳源）来与常驻微生物群竞争并在小鼠肠道中持续存在。鲍曼不动杆菌编码分解代谢鸟氨酸所必需的鸟氨酸琥珀酰转移酶（AstO），尤其是在微生物多样性增加的情况下。补充膳食鸟氨酸可促进鲍曼不动杆菌的长期粪便排出。相比之下，补充首选碳源——谷氨酸钠或组氨酸——则消除了对鸟氨酸分解代谢的需求。此外，配方奶喂养的人类婴儿肠道中鲍曼不动杆菌的携带率更高，这些婴儿通常摄入较高水平的蛋白质，这揭示了饮食对不动杆菌定植的影响。总之，这些结果表明鸟氨酸分解代谢促进了鲍曼不动杆菌的定植，为病原体传播提供了一个储存库。
