ObjectiveTo investigate the diagnostic value of lateral chromatography for cryptococcal capsular polysaccharide antigen in cryptococcal infection.MethodsThe data of patients who detected cryptococcal capsular polysaccharide antigen in West China Hospital of Sichuan University in 2018 were collected. The sensitivity, specificity, positive predictive value and negative predictive value of cryptococcal capsular polysaccharide antigen detected by lateral chromatography were analyzed. The samples with positive lateral chromatography and definite clinical diagnosis were compared with the results of ink staining and fungal culture.ResultsA total of 721 cases were detected. The sensitivity, specificity, positive predictive value and negative predictive value of lateral chromatography detection were 100.00%, 99.39%, 93.93%, 100.00%, respectively. The positive rates of ink staining, fungal culture and cryptococcal capsular polysaccharide antigen for cryptococcal infection were 63.46%, 48.00% and 100.00%, respectively. Sixty-two patients were clinically diagnosed, including 45 cases of cryptococcal meningitis (72.58%), 16 cases of cryptococcal pneumonia (25.81%), and 1 case of bone cryptococcal infection (1.61%).ConclusionsLateral chromatography detection for cryptococcal capsular polysaccharide antigen shows well performing sensitivity and specificity in the diagnosis of cryptococcal infection. Considering its rapid and simple pre-operation, cryptococcal capsular polysaccharide antigen detection with lateral chromatography has good application value for early diagosis of cryptococcal infection.
Objective To analyze the drug resistance of Mycobacterium tuberculosis complex (MTBC) in West China Hospital of Sichuan University in recent years to provide reference for drug resistance monitoring and prevention strategies of tuberculosis in general hospitals. Methods The clinical strains of MTBC that performed drug susceptibility tests in West China Hospital of Sichuan University between January 2019 and December 2022 were collected. The drug susceptibility information of 13 anti-tuberculosis drugs, namely rifampicin, isoniazid, ethambutol, streptomycin, rifabutin, amikacin, kanamycin, ofloxacin, levofloxacin, moxifloxacin, para-aminosalicylic acid, ethionamide, and capreomycin, was collected and retrospectively analyzed. Results A total of 502 clinical strains of MTBC were included, and 366 of them were isolated from newly-treated patients while 136 form re-treated patients. The resistance rates of MTBC strains to the first-line anti-tuberculosis drugs in descending order were 28.69% (isoniazid), 19.72% (ethambutol), and 14.94% (rifampicin). Among the second-line drugs, the resistance rates to ofloxacin, levofloxacin, and moxifloxacin were 13.55%, 12.15%, and 11.95%, respectively. The resistance rates to amikacin, kanamycin, para-aminosalicylic acid, and ethionamide were all less than 10%. The resistance rates to streptomycin, capreomycin, and rifabutin were 17.53%, 13.55%, and 12.15%, respectively. The resistance rates to the remaining 12 anti-tuberculosis drugs except capreomycin of MTBC strains isolated from re-treated patients were higher than those of MTBC strains isolated from newly-treated patients, and the differences were statistically significant (P<0.05). The isolation rates of monodrug-resistant, polydrug-resistant, multidrug-resistant (MDR) and pre-extensively drug-resistant (pre-XDR) strains were 9.36%, 7.37%, 7.17%, and 7.77%, respectively. The isolation rates of strains with the four drug-resistant phenotypes generally showed a downward trend during the four years, and the changing trends were statistically significant (P<0.05). The isolation rates of MDR and pre-XDR strains from re-treated patients were higher than those from newly-treated patients, and the differences were statistically significant (P<0.001). Conclusion Tuberculosis drug resistance in West China Hospital of Sichuan University, which is a comprehensive tuberculosis-designated hospital, remained severe during the four years from 2019 to 2022, and the prevention of tuberculosis and the monitoring of drug resistance should be further strengthened.
ObjectiveTo evaluate the accuracy and practicability of matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) in clinical isolates of mycobacteria.MethodsWe collected all tested strains, which were positive for Mycobacterium tuberculosis culture and positive for acid-fast staining, from West China Hospital of Sichuan University from 2014 to 2017, eliminating duplicate strains sent by the same patient at the same time. The traditional method was used with the P-nitrobenzoic acid (PNB)/ 2-Thiophenecarboxylic acid hydrazide (TCH) indicator to initially identify acid-resistant positive strains. Mycobacteria was identified by MALDI-TOF MS; the specificity and sensitivity of the MALDI-TOF MS was analyzed by duplex primer-polymerase chain reaction (Duplex-PCR) method and DNA sequencing method as the "gold standard" for the identification.ResultsA total of 237 anti-acid positive strains were collected; Mycobacterium tuberculosis complex (MTC) and non-tuberculous mycobacteria (NTM) were identified by mycobacterium double primer PCR, and NTM was identified by 16S rRNA gene sequencing. There were 218 cases of MTC and 19 cases of NTM. The results of preliminary identification using the traditional identification method of PNB/TCH indicator showed that there were 209 cases of MTC (with the sensitivity of 95.9%, specificity of 100.0%, positive predictive value of 100.0%, and negative predictive value of 67.9%) and 28 cases of NTM (with the sensitivity of 100.0%, specificity of 95.9%, positive predictive value of 67.9%, and negative predictive value of 100.0%). The results of MALDI-TOF MS method indicated that there were 199 cases of MTC (with the sensitivity of 91.3%, specificity of 100.0%, positive predictive value of 100.0%, and negative predictive value of 50.0%), 32 cases of NTM (with the sensitivity of 68.4%. specificity of 94.0%, positive predictive value of 40.6%, and negative predictive value of 97.1%), and 6 cases of others. There were 168 strains (84.4%) with the identification score>1.9 obtained by MALDI-TOF MS method.ConclusionsMALDI-TOF MS is a better method for identifying mycobacteria, which has the same identification results as the traditional methods, and has low cost and is suitable for routine use in clinical microbiology laboratories.