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Kin-Sang Chan

Publications and source records attributed to Kin-Sang Chan.

7 recordsLinked to original sources
PubMed2006

Diagnostic application of genotypic identification of mycobacteria.

This study evaluated conventional methods, GLC and three molecular tests, including 16S rRNA sequencing, for the identification of mycobacteria, and the experiences of the authors with the integration of these methods into a diagnostic clinical laboratory were also recorded. Of 1067 clinical isolates of mycobacteria identified by conventional tests, 365 were tested by Accuprobe hybridization assays and PCRs specific for Mycobacterium tuberculosis (MTB) complex or Mycobacterium avium complex (MAC), 202 were tested by 16S rRNA sequencing, and 142 were tested by GLC. Three runs of all tests were performed on a weekly basis. The identifications for 209 MTB complex and 118 MAC isolates obtained by species-specific PCR were in complete agreement with AccuProbe hybridization and conventional test results. The 16S rRNA sequence-based identification, at a similarity of > or =99 %, for 132 of 142 isolates was concordant with the identifications made by the biochemical methods, and for 134 isolates was concordant with the identifications made by GLC at species, group or complex level. 16S rRNA sequencing resulted in fewer incorrectly identified or unidentified organisms than GLC or conventional tests. For the slowly growing non-tuberculous mycobacteria, the mean turnaround times for identification were 4-5 days for 16S rRNA sequencing, 14-29 days for GLC and 22-23 days for conventional methods. Considering the large proportion of some species among clinical isolates, a strategy of initial screening with species-specific PCR (or AccuProbe assays) for the MTB complex and MAC, followed by direct sequencing of the strains that yield negative results, should make 16S rRNA sequencing more affordable for routine application in diagnostic laboratories.

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PubMed2006

Scanning laser polarimetry in pulmonary tuberculosis patients on chemotherapy.

INTRODUCTION: The aim of this study was to analyse the thickness of the retinal nerve fibre layer (RNFL) of pulmonary tuberculosis patients on ethambutol and isoniazid. MATERIALS AND METHODS: This was a prospective cohort study where patients with newly diagnosed pulmonary tuberculosis requiring chemotherapy, including ethambutol and isoniazid, were imaged using scanning laser polarimetry. Their mean baseline RNFL thickness and various scanning laser polarimetry parameters of both eyes were measured 2 weeks after the commencement of chemotherapy. The measurements were repeated at 3 months and 6 months after treatment. The various parameters of the baseline and the follow-up measurements were compared using paired sample t-test with Bonferroni correction. RESULTS: Twenty-four patients (16 males and 8 females; mean age, 51.0 +/- 17.6 years) were recruited. There was no statistically significant difference between the baseline and the follow-up measurements in RNFL thickness and all other scanning laser polarimetry parameters. CONCLUSION: In this cohort of subjects, there was no subclinical change in RNFL thickness detected by scanning laser polarimetry in pulmonary tuberculosis patients on chemotherapy, including ethambutol and isoniazid, after 6 months of treatment.

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PubMed2005

Viral load distribution in SARS outbreak.

An unprecedented community outbreak of severe acute respiratory syndrome (SARS) occurred in the Amoy Gardens, a high-rise residential complex in Hong Kong. Droplet, air, contaminated fomites, and rodent pests have been proposed to be mechanisms for transmitting SARS in a short period. We studied nasopharyngeal viral load of SARS patients on admission and their geographic distribution. Higher nasopharyngeal viral load was found in patients living in adjacent units of the same block inhabited by the index patient, while a lower but detectable nasopharyngeal viral load was found in patients living further away from the index patient. This pattern of nasopharyngeal viral load suggested that airborne transmission played an important part in this outbreak in Hong Kong. Contaminated fomites and rodent pests may have also played a role.

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PubMed2004

Initial viral load and the outcomes of SARS.

BACKGROUND: Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus. It may progress to respiratory failure, and a significant proportion of patients die. Preliminary data suggest that a high viral load of the SARS coronavirus is associated with adverse outcomes in the intensive care unit, but the relation of viral load to survival is unclear. METHODS: We prospectively studied an inception cohort of 133 patients with virologically confirmed SARS who were admitted to 2 general acute care hospitals in Hong Kong from Mar. 24 to May 4, 2003. The patients were followed until death or for a minimum of 90 days. We used Cox proportional hazard modelling to analyze potential predictors of survival recorded at the time of presentation, including viral load from nasopharyngeal specimens (measured by quantitative reverse transcriptase polymerase chain reaction [PCR] of the SARS-associated coronavirus). RESULTS: Thirty-two patients (24.1%) met the criteria for acute respiratory distress syndrome, and 24 patients (18.0%) died. The following baseline factors were independently associated with worse survival: older age (61-80 years) (adjusted hazard ratio [HR] 5.24, 95% confidence interval [CI] 2.03-13.53), presence of an active comorbid condition (adjusted HR 3.36, 95% CI 1.44-7.82) and higher initial viral load of SARS coronavirus, according to quantitative PCR of nasopharyngeal specimens (adjusted HR 1.21 per log10 increase in number of RNA copies per millilitre, 95% CI 1.06-1.39). INTERPRETATION: We found preliminary evidence that higher initial viral load is independently associated with worse prognosis in SARS. Mortality data for patients with SARS should be interpreted in light of age, comorbidity and viral load. These considerations will be important in future studies of SARS.

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PubMedDate not supplied

High-resolution computed tomography is useful for early diagnosis of severe acute respiratory syndrome-associated coronavirus pneumonia in patients with normal chest radiographs.

OBJECTIVE: We investigated the usefulness of high-resolution computed tomography (HRCT) in early detection of severe acute respiratory syndrome (SARS)-associated coronavirus pneumonia and analyzed HRCT findings associated with potentially more severe disease. METHODS: All patients with suspected SARS and normal chest radiographs on admission within the study period were subjected to HRCT examination. The clinical, radiologic, and laboratory data of patients who were confirmed to have SARS-associated coronavirus infection by a positive nasopharyngeal aspirate, stool or urine reverse transcription-polymerase chain reaction (RT-PCR) and/or serological testing were prospectively followed up and analyzed. Characteristics of patients admitted to the intensive care unit (ICU) and those that were not were compared. RESULTS: Among 47 suspected SARS patients with normal chest radiographs, 27 had SARS-associated coronavirus infection confirmed by RT-PCR and/or positive serological testing. Twenty-five of the 27 (93%) patients had HRCT changes compatible with atypical pneumonia, and all 25 patients developed SARS with progressive clinical deterioration. Ten (40%) had unifocal diseases, and 15 had multifocal diseases (60%). Ten (40%) patients had the diseases confined to 1 single lung in the first HRCT, and both lungs were involved at initial presentation in 15 (60%) patients. Concerning the overall extent of the disease at initial presentation, 3 (12%) patients had disease process in all lobes, and the disease was confined to 1 single lobe in 10 (40%) patients. The disease process was mainly peripheral in location (96%), and the lower lobes were more commonly involved (68% in the left lower lobe and 64% in the right lower lobe). Small parapneumonic effusions occurred in 1 (4%) patient. None of the patients with unifocal lesions or single-lung involvement were admitted to the ICU (P < 0.05) (in both comparisons). Subsequent follow-up of the 2 (7%) patients with normal HRCT on admission showed that they were having nonpneumonic SARS-associated coronavirus infection only and were eventually denotified from having SARS. CONCLUSIONS: HRCT is useful for early diagnosis of SARS-associated coronavirus pneumonia in patients with normal chest radiographs. HRCT findings in these patients predict potentially severe disease.

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