Infections of () affect 42.1 % of the Chinese population and 43.1 % of the world population. inhabits the mucous sublayer at the pylorus, leading to gastric ulcers, gastritis, and even cancer. Oral antibiotics are usually used to treat infections, whereas traditional quadruple therapy has side effects including headaches, nausea, diarrhea, intestinal dysbacteriosis, antibiotic resistance, and repeat infections. Here, a drug-loaded magnetic microbullet was designed to realize long-term retention in the stomach for one-shot treatment for infections. It comprises a hollow cylinder wherein eight microneedles homogenously distribute at the top and several round pores located at the bottom. It was three-dimensional (3D)-printed by stereolithography. A clarithromycin (CAM) ground mixture (CGM) was prepared to improve solubility. Enough CGM powders were filled into the cylinder, covered by a small round magnet, and sealed to form a CAM-loaded magnetic microbullet (CMMB). CAM continually released from CMMBs for >24 h. With outside magnetic guidance, an oral CMMB targeted the pylorus site and the microneedles immediately headed into the mucosa followed by long-term local drug release. The and safety of CMMBs was confirmed, where their swelling rates were low, and the oral CMMB was finally completely evacuated. An oral CMMB was administered to -infected mice and maintained in the stomach for 36 h with magnetic guidance, and the successful eradication of was confirmed after single-dose administration. Oral CMMBs are a convenient medication for the eradication of .