Biomedical subjects

Tsi-Shu Huang

Publications and source records attributed to Tsi-Shu Huang.

8 recordsLinked to original sources

PubMed2005

Trends in fluoroquinolone resistance of Mycobacterium tuberculosis complex in a Taiwanese medical centre: 1995-2003.

OBJECTIVES: Fluoroquinolones are being used more frequently for the treatment of multidrug-resistant (MDR) strains of Mycobacterium tuberculosis complex (MTB). This study was designed to determine the frequency of the emergence of fluoroquinolone-resistant strains in Taiwan and to assess whether this might be due to use of fluoroquinolones for treatment of patients with MDR or because of increased use of fluoroquinolones in the community for treatment of other infections. We also sought to determine whether there might be clonal spread of fluoroquinolone resistance. METHODS: A total of 3497 clinical isolates of M. tuberculosis complex were obtained during 1995-2003, of which 141 were selected. They consisted of 62 isolates fully susceptible to four first-line drugs, 33 isolates resistant to rifampicin and isoniazid (MDR), and 46 isolates with a variety of any drug resistant patterns other than MDR (combination group). The MICs were determined for ciprofloxacin, ofloxacin and levofloxacin. RESULTS: An increase in the MIC90 and rates of resistance to ciprofloxacin, ofloxacin and levofloxacin were noted only in the MDR group. The rates were higher among strains isolated between 1998-2003 compared with those obtained between 1995-1997 (rate of resistance, 20% versus 7.7%; MIC > or = 4 mg/L versus 1-2 mg/L). Among the 10 fluoroquinolone-resistant isolates, five (50%) possessed mutations other than S95T in the gyrA gene. No gyrB mutation was found in any of the clinical isolates. CONCLUSIONS: These findings suggest that fluoroquinolone resistance is the result of treatment of patients with MDR strains rather than from use in the general community in Taiwan. The emergence of fluoroquinolone resistance among MDR strains reinforces the need for routine fluoroquinolone susceptibility testing whenever these drugs might be used.

Amino Acid Substitution↗

PubMed2005

Discordant molecular characterization results in a Mycobacterium avium complex strain isolated from an AIDS patient.

This report describes an unusual strain of Mycobacterium avium complex isolated from the sputum of an immunocompromised AIDS patient, which did not react with the MAC probe of the BDProbe Tec system, but was identified as Mycobacterium intracellulare by 16S rRNA gene sequencing. Its PCR restriction-enzyme analysis pattern was compatible with an allelic variant of M. avium. It was scotochromogenic, slow-growing and phenotypically identified as Mycobacterium scrofulaceum. Its clinical significance is not certain.

Acquired Immunodeficiency Syndrome↗

PubMed2005

Preservation of clinical isolates of Mycobacterium tuberculosis complex directly from MGIT culture tubes.

Preservation of M. tuberculosis complex strains isolated from clinical specimens is important for epidemiological investigations related to tuberculosis. In this study the efficacy of preservation was evaluated by calculating the recovery rate of preserved strains, with various patterns of resistance, after periods of storage and subculture. The recovery rates from strains preserved in enriched solid medium were >90% for storage periods <or=6 yr. However, this procedure for storing mycobacteria is time-consuming, labor-intensive, and impractical for routine use in a clinical laboratory setting. This study shows that recovery rates for strains preserved directly from MGIT fluids are satisfactory for storage periods <or=2 yr. No significant difference in viability was observed within 3 categories of drug resistance: (i) all-susceptible, (ii) multi-drug resistant (MDR), and (iii) a combination of other patterns of resistance. Preserving clinical M. tuberculosis strains directly from MGIT culture fluid fits easily into laboratory routine and is feasible for use in a clinical laboratory setting.

Culture Media↗

PubMed2005

Streptococcus suis meningitis with ventriculoperitoneal shunt infection and spondylodiscitis.

Streptococcus suis is a zoonotic pathogen which causes meningitis, bacteremia, and endocarditis in pigs. Human infection is rare and often presents as meningitis with the sequela of permanent deafness and endocarditis. Previous cases were reported from pig-rearing countries such as Holland and Hong Kong. We report a 55-year-old bedridden man with S. suis meningitis complicated with ventriculoperitoneal shunt infection and lumbar spine spondylodiscitis. He presented with fever, delirium, neck stiffness, lower leg weakness and sudden onset hearing loss for several days. He was successfully treated with intravenous antibiotics, ventriculoperitoneal shunt replacement, lumbar spinal laminotomy and discectomy. Cerebrospinal fluid culture initially misidentified the organism as Streptococcus acidominimus, and S. suis was later identified by 16S rRNA sequencing. Misidentification of the microbiological findings may lead to a failure to correctly diagnose this disease. S. suis meningitis should be included in the differential diagnosis of patients with meningitis and sudden hearing loss.

Anti-Bacterial Agents↗

PubMed2004

Use of MGIT 960 for rapid quantitative measurement of the susceptibility of Mycobacterium tuberculosis complex to ciprofloxacin and ethionamide.

OBJECTIVES: Tentative standards for testing MICs for Mycobacterium tuberculosis include agar dilution and the BACTEC method. However, the conventional agar dilution method requires 3-5 weeks to complete; whereas BACTEC, although a rapid test, involves the use of radioisotopes. In contrast, the MGIT 960 system uses a fluorescence quenching based oxygen sensor that can be read automatically. This system is not only robust, safe and simple, but has been validated for susceptibility tests of first-line antituberculous agents. METHODS: We evaluated 46 clinical strains of M. tuberculosis isolated from patients admitted to Kaohsiung Veterans General Hospital. Testing of MICs of ciprofloxacin and ethionamide was carried out by MGIT 960 and compared with the agar dilution method. RESULTS: Good agreement was found between MGIT 960 and agar dilution. The greatest concordance between the agar dilution and MGIT assay at +/-1 and +/-2 dilution was 80.4% and 97.8% for ciprofloxacin, and 82.6% and 93.5% for ethionamide, respectively. CONCLUSION: MGIT 960 was found to be comparable to the current NCCLS standard method, agar dilution, and has the advantage of being rapid (obtaining results within 5-17 days, average 8.9 days) and easy to achieve standardization.

Antitubercular Agents↗

PubMed2003

Rapid detection of pulmonary tuberculosis using the BDProbeTEC ET Mycobacterium tuberculosis Complex Direct Detection Assay (DTB).

The ability to rapidly detect tubercle bacilli in respiratory secretions was determined for the BDProbeTEC ET Mycobacterium tuberculosis Complex Direct Detection Assay in comparison with the acid-fast smear (AFS). A total of 267 respiratory specimens obtained from 89 patients were evaluated. The DTB assay was positive in 70 of 78 culture positive specimens (89.7%) and 12 of 177 culture negative specimens (6.8%). The AFS was positive in 33 of 78 culture positive specimens (42.3%) and 3 of 186 culture negative specimens (1.6%). The sensitivity, specificity, positive predictive value, and negative predictive value of DTB assay were 89.7%, 93.7%, 85.4%, and 95.7%, respectively. The sensitivity of a single DBT (74.4%) was 2.1-times greater than three AFS (35.9%). The greater cost of the DTB assay compared to the AFS was compensated by its valuable information for the diagnosis and control of tuberculosis. These results demonstrated the clinical usefulness of the DTB assay for the rapid diagnosis of tuberculosis in respiratory specimens.

Bacteriological Techniques↗

PubMed2003

Correlation between pyrazinamide activity and pncA mutations in Mycobacterium tuberculosis isolates in Taiwan.

A total of 76 clinical Mycobacterium tuberculosis isolates from Taiwan were tested for pyrazinamidase activity, pyrazinamide susceptibility, and pncA mutations. Frequency of resistance to PZA rose with increases in resistance to first-line drugs. Of 17 pyrazinamide-resistant strains, 7 (3 of which had not been previously described) possessed mutations in the pncA gene.

Amidohydrolases↗

PubMed2002

Antimicrobial susceptibility testing of Mycobacterium tuberculosis to first-line drugs: comparisons of the MGIT 960 and BACTEC 460 systems.

The reliability of the Mycobacteria Growth Indicator Tube (MGIT) 960 system for rapid antimicrobial susceptibility testing (AST) of Mycobacterium tuberculosis was evaluated. Forty-seven isolates, including 10 fully susceptible and 37 resistant strains, were tested for susceptibility to the critical concentrations of streptomycin (STR), isoniazid (INH), rifampin (RMP), and ethambutol (EMB), as recommended by the manufacturer. Strains resistant to the critical concentrations were tested with higher concentrations. The results were compared to those obtained by a radiometric method (BACTEC 460TB) and by a conventional agar dilution method, which served as the reference method. Based on these data, we suggest that the following antibiotic concentrations give satisfactory results with the MGIT 960 system: STR, 4.0 microg/ml; INH, 0.1 microg/ml; RMP, 1.0 microg/ml; and EMB, 5.0 microg/ml. The time required to obtain susceptibility results averaged 6.9 days by the MGIT 960 system and 5.4 days by the BACTEC 460TB system; these intervals were not significantly different. This study shows that the MGIT 960 system is a reliable, rapid, automated method for testing the susceptibility of M. tuberculosis isolates to first-line drugs.

Antitubercular Agents↗