A Rare Case Report of Skin Infection Caused by Nocardia brasiliensis in an HIV Patient.

Abstract

Background: In October 2023, our hospital confirmed a case of a patient with HIV with concurrent infection with Nocardia brasiliensis. A patient with HIV developed a lump on the surface of the dorsum of his left hand without any obvious cause. He used a nail clipper to trim it. Due to improper disinfection and treatment methods, the condition worsened, and he subsequently sought medical attention at our hospital. A series of clinical laboratory tests were conducted based on the patient's medical history, symptoms, and signs. Based on the test results, a reasonable clinical treatment plan was adopted, ultimately achieving satisfactory treatment outcomes for the patient.

Methods: Clinical implementation of pus bacterial culture and identification (matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry, MALDI-TOF MS), serum anti HIV detection, and Treponema pallidum antibody detection. Additional related auxiliary examinations: blood routine, liver function, kidney function, CRP, electrolytes.

Results: Blood routine and CRP (venous blood): White blood cell count 16.00 x 109/L, total number of lymphocytes 3.73 x 109/L, total monocyte count 1.66 x 109/L, total number of neutrophils 10.37 x 109/L, total number of basophils 0.10 x 109/L, average platelet volume 8.8 fL, whole blood high-sensitivity C-reactive protein 46.44 mg/L, urine routine: protein+-. Liver function test: Albumin 37.7 g/L, aspartate aminotransferase 55.5 U/L, alanine aminotransferase 63.7 U/L, blood lipid test: triglycerides 2.22 mmol/L, high-density lipoprotein cholesterol 0.77 mmol/L, coagulation function test: fibrinogen test 5.69 g/L, lymphocyte subgroup analysis: T4/T8 cell ratio 0.78, total mature T cell count 2.501 x 109/L, T8 cell count 1.351 x 109/L, B cell count 0.574 x 109/L. Serum pathogen test: anti HIV positive, Treponema pallidum antibody 214.70 IU/mL, unheated serum reactive hormone test positive (1:8). Gram staining of pus: a large number of Gram positive bacteria were found, arrange in a branching form, weak acid-fast staining: positive, pus culture and bacteria identified (MALDI-TOF MS): Nocardia brasiliensis. Clinical treatment includes trimethoprim/sulfamethoxazole 800 mg/160 mg po q12 hours, local wet compress with Baiduobang ointment, and abscess incised and drained. Seven days later, the patient had a circular ulcer on the left back without any new pustules. Slightly elevated skin temperature, no tenderness, and no purulent or bloody secretions. His condition had improved and he was discharged. Follow up infectious disease specialist hospitals treat HIV, syphilis, and other related diseases.

Conclusions: Patients with HIV are prone to various types of infections, even rare bacteria, as their immune function decreases. At present, there are few reports about a patient with HIV with concurrent infection with Nocardia brasiliensis. This case can provide reference for clinical diagnosis and treatment of related diseases in the future. In addition, with the popularity of new identification methods such as mass spectrometry, laboratories should pay attention to traditional staining methods and use microscopes to detect pathogens.