Pseudomonas Infections in the Common Marmoset (Callithrix jacchus): Gross and Histopathological Findings

Common marmosets (Callithrix jacchus) are a New World nonhuman primate (NHP) whose popularity as a research model continues to expand. Marmosets were identified as the predominant NHP species that is susceptible to spontaneous Pseudomonas infections based on a 27-year survey in a primate colony, encompassing several NHP species. 26 common marmosets were retrospectively identified and evaluated for spontaneous Pseudomonas spp. infections. Clinical symptoms included lethargy, weight loss, gastrointestinal issues (diarrhea, bloating, vomiting, poor appetite), increased respiratory effort, and difficulty urinating. Affected organs (larynx, lungs, liver, gallbladder, intestines, colon, uterus, and urinary bladder) appeared discolored, distended, or enlarged. Microscopic findings included inflammatory infiltrates, edema, necrosis, hemorrhage, and pseudomembranous lesions. Only animals with clinical symptoms or gross evidence of bacterial infection were cultured; therefore, the actual incidence of Pseudomonas spp. infections is unknown. We present the common and uncommon lesions associated with Pseudomonas infections in the common marmoset.