A Rare Case of Coinfection of Rhodococcus equi and Nocardia abscessus in an Immunocompetent Human Host.

Background: Rhodococcus and Nocardia spp. are aerobic, gram-positive bacteria distributed extensively in the sediment of various environments globally. They usually manifest as opportunistic infections in immunocompromised hosts. Here, we report a coinfection case of Rhodococcus and Nocardia spp. in a patient with normal immune system.

Case presentation: We present a case of a 52-year-old healthy man who sustained right hand injury at work. The patient exhibited post-traumatic infection. The skin of the right palm was swollen with acute pain, and active flexion and extension of his fingers were limited. Ultrasound scanning of the dorsolateral aspect of the right hand showed an uneven echogenic area of about 3.5 cm × 1.3 cm × 0.9 cm in the deep surface of the extensor muscles between the 4th and 5th metacarpals. The patient underwent right hand debridement and negative pressure suction under brachial plexus anesthesia. After bacterial cultures of the pus and necrotic tissues, Rhodococcus equi and Nocardia abscessus were determined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) (Zybio, China). Treatment with a combination of levofloxacin and sulfamethoxazole led to a favorable clinical outcome.

Conclusion: This report highlights the necessity and urgency of precise species identification, providing a critical guide for physicians in the choice of targeted treatment.