ObjectiveTo explore the clinical value of metagenomic next-generation sequencing (mNGS) in diagnosis and treatment of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). MethodsBetween April 2020 and March 2023, 10 patients with PJI after TKA were admitted. There were 3 males and 7 females with an average age of 69.9 years (range, 44-83 years). Infection occurred after 8-35 months of TKA (mean, 19.5 months). The duration of infection ranged from 16 to 128 days (mean, 37 days). The preoperative erythrocyte sedimentation rate (ESR) was 15-85 mm/1 h (mean, 50.2 mm/1 h). The C reactive protein (CRP) was 4.4-410.0 mg/L (mean, 192.8 mg/L). The white blood cell counting was (3.4-23.8)×109/L (mean, 12.3×109/L). The absolute value of neutrophils was (1.1-22.5)×109/L (mean, 9.2×109/L). After admission, the joint fluid was extracted for bacterial culture method and mNGS test, and sensitive antibiotics were chosen according to the results of the test, and the infection was controlled in combination with surgery. Results Seven cases (70%) were detected as positive by bacterial culture method, and 7 types of pathogenic bacteria were detected; the most common pathogenic bacterium was Streptococcus lactis arrestans. Ten cases (100%) were detected as positive by mNGS test, and 11 types of pathogenic bacteria were detected; the most common pathogenic bacterium was Propionibacterium acnes. The difference in the positive rate between the two methods was significant (P=0.211). Three of the 7 patients who were positive for both the bacterial culture method and the mNGS test had the same results for the type of pathogenic bacteria, with a compliance rate of 42.86% (3/7). The testing time (from sample delivery to results) was (4.95±2.14) days for bacterial culture method and (1.60±0.52) days for mNGS test, and the difference was significant (t=4.810, P<0.001). The corresponding sensitive antibiotic treatment was chosen according to the results of bacterial culture method and mNGS test. At 3 days after the one-stage operation, the CRP was 6.8-48.2 mg/L (mean, 23.6 mg/L); the ESR was 17-53 mm/1 h (mean, 35.5 mm/1 h); the white blood cell counting was (4.5-8.1)×109/L (mean, 6.1×109/L); the absolute value of neutrophils was (2.3-5.7)×109/L (mean, 4.1×109/L). All patients were followed up 12-39 months (mean, 23.5 months). One case had recurrence of infection at 6 months after operation, and the remaining 9 cases showed no signs of infection, with an infection control rate of 90%. Conclusion Compared with bacterial culture method, mNGS test can more rapidly and accurately detect pathogenic bacteria for PJI after TKA, which is important for guiding antibiotics combined with surgical treatment of PJI.
Objective To evaluate the clinical value of loop-mediated isothermal amplification chip (LAMP) in pathogen detection for acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods We retrospectively analyzed qualified lower respiratory tract specimens from AECOPD patients treated at West China Hospital of Sichuan University between February 2021 and December 2022. Both LAMP and conventional culture methods were performed simultaneously to compare their positive detection rates, pathogen profiles, and diagnostic consistency (Kappa test). Subgroup analysis was further performed based on the site of infection [community acquired pneumonia (CAP) vs. hospital acquired pneumonia (HAP)]. Results A total of 159 patients were included. Among the 159 specimens, the overall positive rate of LAMP was significantly higher than that of the culture method [36.5% (58/159) vs. 30.2% (48/159)]. Significant differences in positive rates were observed for Acinetobacter baumannii (13.8% vs. 11.3%) and Pseudomonas aeruginosa (9.4% vs. 7.5%). The LAMP chip method detected mixed infections in 13 cases and additionally identified 6 cases of Mycobacterium tuberculosis complex. Consistency analysis between the two methods for respiratory pathogen detection showed statistically significant agreement for Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia, and Haemophilus influenzae (P<0.05). In the CAP subgroup, only the LAMP method exclusively detected Mycobacterium tuberculosis complex (5.6%), Streptococcus pneumoniae (2.8%), Staphylococcus aureus (0.9%), and Escherichia coli (1.9%). In the HAP subgroup, only the LAMP method exclusively detected MRSA (3.8%). Significant differences in positive rates between the two methods for multiple pathogens were observed in both CAP and HAP groups (P<0.05). Conclusions For pathogen detection in AECOPD patients, the LAMP method offers rapid (only 2 hours), simple and efficient testing, particularly valuable for mixed infection screening. It shows advantages in detecting fastidious pathogens in community-acquired pneumonia, and providing guiding significance for early precise anti-infective therapy.