The patient was started to use methylprednisolone for anti-inflammatory, ceftriaxone and moxifloxacin for anti-infection, azivudine for antiviral, and thymosin to enhance immunity. However, the treatment was not effective, and the patient's asthma and sputum cough symptoms worsened, and his blood oxygen level continued to decline. Bedside fiberoptic bronchoscopy revealed tracheomalacia and collapse with white mucoid sputum. The patient was subsequently transferred to the intensive care unit (ICU) and received endotracheal intubation, mechanical ventilation, and enteral nutritional support.

While in the ICU, the patient underwent multiple bronchoalveolar lavage (BALF) and metagenomic sequencing (mNGS), and the results showed the presence of multiple infections, including Enterococcus faecalis, Candida tropicalis, Pseudomonas aeruginosa, ESBL-producing pan-drug-resistant Klebsiella pneumoniae (PDR-KP), and pan-drug-resistant Acinetobacter baumannii. The patient was treated with a variety of antibiotics and antifungal drugs, including teicoplanin, cefoperazone and sulbactam, micafungin, voriconazole, tigecycline, and polymyxin B.

During hospitalization, the patient began to suffer from recurrent diarrhea on the 50th day, and conventional antidiarrheal and probiotic treatments were ineffective. The 16S gut microbiota test showed that the diversity of the patient's gut microbiota was reduced, nutritional anabolism was abnormal, the abundance of Klebsiella pneumoniae increased, and beneficial bacteria such as Prevotella, Ruminococcus, and Lactobacilli decreased significantly. In view of the severe imbalance of the patient's gut microbiota, it was decided to undergo fecal microbiota transplantation (FMT).

FMT treatment plan: On the 68th day of hospitalization, fecal bacterial suspension from a healthy donor was injected into the patient through a nasojejunal tube, 150 mL each time, a total of 4 times, lasting 6 days.

(Left) February 1, 2023; (Right) March 23, 2023

After the first FMT, the patient's diarrhea stopped and endotracheal secretions significantly decreased, and micafungin was subsequently discontinued. All antimicrobials were discontinued on day 73, and the frequency of bronchoscopy was reduced to once every 2 days.

After 4 FMT treatments, the patient's symptoms improved significantly, and multiple stool tests and culture results were negative. Intestinal microbiota analysis 27 days after FMT showed an increase in the abundance of beneficial bacteria and a significant decrease in the relative abundance of Klebsiella pneumoniae.

Chest CT results showed that the patient had double pneumonia and the pleural effusion gradually absorbed. On day 122, the BALF culture result was negative. The patient was successfully discharged from hospital on day 133.

(Left) April 18, 2023; (Right) May 8, 2023

In this case, FMT not only improved the patient's gut microbiota imbalance, but also significantly inhibited the infection by pan-drug-resistant Klebsiella pneumoniae. After FMT, the abundance of beneficial bacteria in the patient's intestines increased, the relative abundance of Klebsiella pneumoniae dropped to undetectable levels, and BALF culture results also confirmed the clearance of PDR-KP. This suggests that FMT may have the potential to inhibit or even eradicate Klebsiella pneumoniae colonization and infection by regulating gut microbiota.