Background: Acinetobacter baumannii (A. baumannii) is one of the most common pathogens that cause hospital-acquired infections. In recent years, drug-resistant A. baumannii has become prevalent worldwide, and pandrug-resistant A. baumannii is increasingly being observed. However, treating pandrug-resistant A. baumannii is very difficult.Case Description: We report a case of an 8-year-old girl with severe pandrug-resistant A. baumannii pneumonia complicated with a diaphragmatic hernia. The patient arrived at Tongji hospital with a fever and cough, and she was admitted to the pediatric intensive care unit with pneumonia. The day after admission, her condition worsened. She had breathing difficulties and loss of consciousness, and a ventilator was used immediately. On the fourth day after being on the ventilator, the sputum culture was positive for A. baumannii. Initially, multiple antibiotic sensitivity tests showed resistance to all antibiotics. This suggested that using antibiotics would be ineffective. After the use of all antibiotics was discontinued for 8 days, susceptibility testing of tigecycline indicated intermediate susceptibility. Following the initiation of tigecycline treatments for 5 weeks, the bacterial infection was progressively controlled, the diaphragmatic hernia disappeared, and the patient gradually recovered.Conclusions: Antibiotic sensitivity to pandrug-resistant A. baumannii can be restored by discontinuation of antibiotics. Antibiotics should be administrated even if the antibiotic sensitivity test shows an intermediary result. For pandrug-resistant A. baumannii, a prolonged monotherapy with a large dose of intermediary tigecycline can achieve good efficacy. In addition, the complication of a diaphragmatic hernia can return to normal after treatment with effective antibiotics, and patients may not necessarily need surgery.