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Biomedical subjects

K Y Yuen

Publications and source records attributed to K Y Yuen.

At least 181 records · Page 10Linked to original sources
PubMed1997

Nocardiosis in systemic lupus erythematosus.

OBJECTIVES: This study was performed to study the clinical presentations, treatment, and outcome of six cases of nocardial infection in the systemic lupus erythematosus (SLE) population living in Hong Kong and compare these cases with those reported in the English literature. METHODS: Records of 215 SLE patients who attended our lupus and rheumatology clinics were reviewed, and cases of nocardial infection were retrieved and studied in detail. A Medline search from 1966 to 1995 was performed to identify other reported cases. The microbiology, diagnosis, and treatment strategies of nocardiosis were assessed. RESULTS: Six cases of nocardiosis were found in our lupus series, giving a prevalence of 2.8%. Another 26 cases of nocardial infection in SLE were reported in the literature. All except one were caused by Nocardia asteroides. The lung was the commonest site of involvement (81%), followed by the central nervous system (CNS) (13%). The mortality was high (35%), especially when the CNS was involved (75%). Sulphonamides were the mainstay of treatment, and adjunctive surgical procedures may be needed for suppurative complications. CONCLUSIONS: Nocardiosis has been increasingly recognized in SLE. Although still uncommon, it is an important opportunistic infection because it is curable and mortality is usually caused by delay in diagnosis and treatment. A high index of suspicion, an aggressive approach to diagnosis, and early empirical therapy are essential principles of management.

Adult↗
PubMed1997

Monitoring the therapy of pulmonary tuberculosis by nested polymerase chain reaction assay.

Monthly clinical and microbiological parameters (by sputum smear, culture and PCR assay), of 50 patients with documented pulmonary tuberculosis and on anti-tuberculosis therapy, were monitored over a period of 18 months. PCR converters (70%) who had PCR conversion before the sixth month of treatment did not have clinical or microbiological evidence of failure or relapse, while nine of 15 PCR persisters (30%) had clinical failure (7) and relapse (2). The PCR persisters were significantly associated with more underlying medical illnesses, high mean radiographic scores on the extent of disease involvement, previous drug treatment, initial sputum smear positivity and multi-drug resistance. Of the eight PCR persisters infected by susceptible Mycobacterium tuberculosis, all had marked residual radiographic changes despite completion of drug therapy. The findings may have important implications in the application of PCR on individualization of the duration of anti-tuberculosis therapy.

Adult↗
PubMed1997

Treatment of adenovirus-associated haemorrhagic cystitis with ganciclovir.

We report a 47-year-old bone marrow transplant recipient with haemorrhagic cystitis caused by adenovirus successfully treated with ganciclovir. This is the first report on the use of ganciclovir for the successful treatment of adenoviral infection. Shell vial culture may be more sensitive than conventional culture in the detection of adenovirus in such patients.

Adenoviridae↗
PubMed1997

Two cases of fatal strongyloidiasis in Hong Kong.

Two cases of fatal strongyloidiasis associated with diabetes mellitus and malnutrition are reported. The patients presented with repeated vomiting and upper gastrointestinal bleeding respectively. Unusual findings in these two patients included: unexplained peripheral leukocytosis, pulmonary infiltrates, gastric aspirate leukocytosis, progression of gastrointestinal symptoms and concurrent presence of adult worms, eggs, filariform and rhabditiform larvae of Strongyloides stercoralis in alimentary canal specimens. Both patients succumbed while receiving treatment with mebendazole. The present report illustrates that unexplained gastrointestinal symptoms with extensive scratch marks below the umbilicus can be important clues to early diagnosis of the disease. In addition, the various presentations of S. stercoralis infestation are discussed with reference to predisposing factors. Current trends in laboratory diagnosis and therapeutic considerations are also delineated.

Aged↗
PubMed1997

Stage-specific manifestation of mold infections in bone marrow transplant recipients: risk factors and clinical significance of positive concentrated smears.

Potassium hydroxide-concentrated smears, prepared from sedimented remains of clinical specimens, were used to distinguish between mold infection and exogenous contamination in fungal culture-positive specimens. This method was applied in the study of 3,857 clinical specimens from 230 bone marrow transplant recipients who were followed up prospectively for infectious complications. Concentrated smears of only 86 (from 21 infected patients) of 149 fungal culture-positive specimens were positive for hyphae; 82 of the strains were Aspergillus species. Concentrated smears of the remaining 63 fungal culture-positive specimens were negative; the strains identified by culture were considered as exogenous contaminants (87% of which were Penicillium species). A stage-specific manifestation of mold infection was observed: 67% of mold infections occurred during acute graft-vs.-host disease (GVHD) a median of 47 days after transplantation, whereas 9% of mold infections occurred as rapidly fatal invasive disease before engraftment. Overall, of the 21 patients with mold infection, 17 (81%) had invasive mold disease, and four (19%) had mold colonization of airways secondary to chronic GVHD after day 100. The significant risk factors for mold infection were total-body irradiation and grade 2-4 acute GVHD. Because of our high mortality rate (82%), the consideration of antimold prophylaxis for such patients may be warranted.

Adolescent↗
PubMed1997

Penicillium marneffei infection in a non-HIV infected child.

We report a case of Penicillium marneffei infection in a previously healthy 3.5 years-old Chinese boy and review the literature. The details of the case are described with emphasis on his immune function and treatment outcome. This boy had transient immunodeficiency involving phagocytic and NK cells due to P. marneffei infection which resolved after treatment with gamma interferon and amphotericin B. A prolonged course of fluconazole of 1 year was successful in preventing relapse. Gamma interferon, amphotericin B and a prolonged course of fluconazole may be useful in the treatment of life-threatening infection by P. marneffei.

Antifungal Agents↗
PubMed1997

Distinct genotypic distributions of cytomegalovirus (CMV) envelope glycoprotein in bone marrow and renal transplant recipients with CMV disease.

A prospective study of the spectrum of glycoprotein B (gB) and glycoprotein H (gH) genotypes of cytomegalovirus (CMV) was conducted with five categories of patients: viremic bone marrow-transplant (BMT) recipients who developed CMV disease after BMT (n = 22), viremic BMT recipients without CMV disease (n = 11), viremic renal-transplant recipients who developed CMV disease after transplantation (n = 14), viremic renal-transplant recipients without CMV disease (n = 13), and premature babies with asymptomatic congenital CMV infections (n = 13). Genotypic stability was observed because the gB and gH genotypes of multiple isolates obtained from a single patient were identical. The distribution of gH genotypes in patients of all groups studied were similar. However, there was a unique distribution of the gB genotype in the first category of patients, i.e., BMT recipients with CMV disease, which was distinct from those of all other categories (P < 0.05). CMV isolates from 54% of BMT recipients with CMV disease exhibited gB type 2, while isolates from 46, 50, 69, and 77% of the BMT recipients without CMV disease, renal-transplant recipients with and those without CMV disease, and premature babies with congenital CMV infection, respectively, were of gB type 1. An analysis of the clinical characteristics of BMT recipients with CMV disease indicated that all underwent either an allogeneic or matched, unrelated donor transplant, and half had severe acute graft-versus-host disease (grades 2 to 4). The statistically significant genotypic difference between CMV isolates from BMT recipients with and without CMV disease was not observed between isolates from renal-transplant recipients with and without CMV disease. We speculate that differences in pathogenesis in different patient groups might account for these observations. These findings would also facilitate decision making about the choice of recombinant CMV glycoprotein vaccine required to immunize transplant donors and the subsequent adoptive transfer of immunity to BMT recipients. When the source of CMV DNA required for genotyping was investigated among renal-transplant recipients, direct use of peripheral blood leukocytes was 95% effective compared to the effectiveness of cells obtained from conventional culture of peripheral blood specimens.

Adult↗
PubMed1997

Comparison of two automated DNA amplification systems with a manual one-tube nested PCR assay for diagnosis of pulmonary tuberculosis.

Eighty-four specimens of respiratory secretions culture positive for mycobacteria (70 positive for Mycobacterium tuberculosis and 14 positive for nontuberculous mycobacteria) and 120 culture-negative specimens were evaluated by three DNA amplification techniques: a manual in-house single-tube nested PCR (nPCR) and two commercial automated assays (the Cobas Amplicor System [aPCR-h] from Roche Diagnostic Systems and the Abbott LCx Probe System [aLCx-p] from Abbott Laboratories). The overall diagnostic sensitivities of the nPCR, aPCR-h, and aLCx-p were 77.1, 84.3, and 77.1%, respectively, and the sensitivities were 57.9, 57.9, and 36.8%, respectively, for smear-negative specimens. Specimens culture positive for nontuberculous mycobacteria were negative by all three assays. Eight culture-negative specimens which were positive by one or more assays had previously been documented by culture to be positive for M. tuberculosis and were taken from patients who were treated with antituberculosis agents. Retesting of specimens negative by one assay by the other two assays revealed that each test had its unique group of negative specimens. When considering the DNA extraction and amplification steps of these assays separately, it was found that extracts from aPCR-h and aLCx-p were compatible with nPCR amplication, while the two automated assays could only amplify extracts processed with their own reagents. Limiting dilution analysis revealed that the order of analytical sensitivity was nPCR, followed by aLCx-p and then aPCR-h. Comparison of the work flow of each assay revealed that although the aPCR-h demands the least specimen handling, the turnaround time of aLCx-p is the most favorable.

Antigens, Bacterial↗
PubMed1997

Detection of CMV DNA in bone marrow transplant recipients: plasma versus leucocyte polymerase chain reaction.

AIMS: To compare the nested polymerase chain reaction (PCR) assay for the detection of cytomegalovirus (CMV) DNA in peripheral blood leucocytes and plasma obtained from heparinised blood; to determine the efficiency of various DNA extraction methods to minimise inhibition of plasma PCR and their effect on the sensitivity of plasma PCR; to determine the inhibitory effect of heparin, dextran, and EDTA on the CMV PCR assay. METHODS: 217 heparinised blood specimens from 58 bone marrow transplant patients were processed and the sensitivities and specificities of the PCR assays using peripheral blood leucocytes and plasma (with simple, Instagene, and Geneclean extraction methods) were compared to those of conventional CMV culture. In a separate experiment, dilutions of heparin, dextran, and EDTA were included in PCR assays. RESULTS: The detection of CMV DNA using peripheral blood leucocytes for PCR assay was significantly more sensitive (100%) than when using plasma (60%). Instagene and Geneclean extraction removed inherent inhibition but did not improve the sensitivity of the plasma PCR reaction. Heparin had an inhibitory effect on PCR. CONCLUSIONS: PCR assay using peripheral blood leucocytes is better than plasma for guiding the prescription of ganciclovir to bone marrow transplant patients. Heparin is inhibitory to the plasma PCR reaction.

Bone Marrow Transplantation↗
PubMed1997

Infectious complications of liver transplantation.

Sixteen (50%) of the 32 patients who received liver transplantations from October 1991 to March 1993 at Queen Mary Hospital, Hong Kong, developed viral, bacterial, or fungal infections. The viral infections were largely a result of immunosuppression while accidental bowel perforation, bile leak at the anastomosis, and delayed onset of stricture of the bile duct anastomosis were responsible for the intra-abdominal bacterial or fungal infections. Although the incidence of infectious complications was high, all patients were managed effectively and only one patient with lymphoproliferative disorder died. Infectious complications can lead to a prolonged hospital stay and a substantially increased hospital cost. The adoption of new immunosuppressive regimes that can better prevent acute graft rejection and adherence to meticulous surgical technique will help to reduce the infectious complications of liver transplantation in the future.

Journal Article↗
PubMed1997

Nucleic acid technology and infectious diseases.

The past decade has witnessed an explosion in the knowledge of microbial genetics, pathogenesis, and antimicrobial resistance as a result of advances in molecular technology. This has brought important breakthroughs in the management of patients with infectious diseases, as organisms that had previously been difficult to demonstrate in vitro can now be detected by molecular techniques such as the polymerase chain reaction. Not only is rapid diagnosis now possible, but old diseases of uncertain aetiology have been found to have an infective origin, for instance, Whipple's disease. Molecular technology has also contributed greatly to epidemiological studies of outbreaks, understanding antimicrobial resistance, developing new antimicrobial agents, the in vitro synthesis of immunomodulators, production of vaccines, and gene therapy. The limitations of these latest technologies, however, need to be remembered so that they yield meaningful information for patient care.

Journal Article↗
PubMed1997

Diagnosing cytomegalovirus disease in CMV seropositive renal allograft recipients: a comparison between the detection of CMV DNAemia by polymerase chain reaction and antigenemia by CMV pp65 assay.

The optimal diagnostic test for CMV disease in renal allograft recipients in a locality with a high CMV seropositive rate has not been fully determined. We compared the usefulness of the CMV pp65 antigenemia (CMV-Ag) assay with the detection of DNAemia by a nested polymerase chain reaction (PCR) method in diagnosing CMV disease in 56 renal allograft recipients, of whom 50 (89.2%) were CMV seropositive prior to transplant (tx). Positive CMV-Ag assays were found in 126/281 samples (44.8%) of 27 patients (48.2%) of whom five had seven episodes of CMV disease. The remaining 22 patients were asymptomatic. The symptomatic patients had significantly higher median peak CMV-Ag levels than the asymptomatic patients [800 (160-1380) vs. 5 (1-604) per 2 x 10(5) peripheral blood leukocyte (PBL), p < 0.0001]. One hundred and eight samples were tested by both CMV-Ag and PCR methods. Out of the 108 samples, 89 showed concordant results (37 positive and 52 negative for both tests). Seventeen samples of 11 patients were CMV-Ag negative/PCR positive. Out of these 11 patients, two had CMV disease and the discrepancy in the results was due to blood samples taken after the start of ganciclovir therapy. Falsely negative PCR tests were found in two samples of two patients with positive CMV-Ag assays. With a outoff antigenemia level of 100 per 2 x 10(5) PBL, the sensitivity, specificity, positive and negative predictive values for diagnosing CMV disease were 100, 96, 71.4 and 100%, respectively. On the other hand, CMV DNAemia was detected in many asymptomatic patients, and the PCR test results correlated poorly with the clinical manifestations of the disease. In symptomatic patients undergoing ganciclovir therapy, the quantification of antigenemia level allowed the assessment of treatment efficacy. In addition, positive CMV-Ag assays at the end of therapy were associated with the subsequent relapse of CMV disease in two patients. The high specificity, together with the short processing time of 4 h, make the CMV-Ag assay the test-of-choice for diagnosing CMV disease in a renal transplant population with a predominance of CMV seropositive patients.

Adolescent↗
PubMed1997

Management of fulminant hepatic failure at Queen Mary Hospital.

OBJECTIVE: To evaluate the strategy of the management of patients with fulminant hepatic failure at Queen Mary Hospital. METHODS: In the period 1994 through 1996, 30 patients with fulminant hepatic failure were managed by active supportive treatment in the Intensive Care Unit in preparation for liver transplantation. Liver transplantation was performed in 14 patients (aged 17-47), 3 of whom received liver grafts from brain-stem dead donors and 11 received live-related grafts from family members. The median duration from admission to liver transplantation was 3 days (range: 1-6 days). RESULTS: Thirteen patients (93%) survived the liver transplantation and are well after a median period of follow-up of 7 months. The only mortality was in a patient with pre-exiting renal transplantation and hepatitis B infection, who died from intra-abdominal candidiasis. CONCLUSION: The strategy of active supportive treatment and early liver transplantation using live-related liver graft is probably the key to the success of the management of fulminant hepatic failure in our series.

Adolescent↗
PubMed1996

The epidemiology of acinetobacter infections in Hong Kong.

A retrospective survey was conducted of the characteristics of acinetobacter infections in Hong Kong--seasonal and geographic distributions, frequency of isolation from various body sites, antimicrobial susceptibility and molecular epidemiology. Most (80%) isolates of Acinetobacter spp. belonged to DNA groups 2 (A. baumannii) or 13, as defined by growth at 44 degrees C. An increased isolation rate in summer was related to higher ambient temperatures. The notion that acinetobacters are opportunist nosocomial pathogens was supported by the body site- and ward-specific distributions, which were similar to those of Pseudomonas aeruginosa and in marked contrast to those of coagulase-negative staphylococci and Escherichia coli. Typing of Acinetobacter isolates by arbitrary-primed polymerase chain reaction revealed extensive genotypic polymorphism, suggesting that numerous unrelated strains were circulating between patients. In view of the association with a high incidence of polymicrobial bacteraemia and multiresistance to antibiotics, a careful selection of appropriate antibiotics in combination is necessary for empirical therapy of infections caused by Acinetobacter spp.

Acinetobacter↗
PubMed1996

Single-tube nested PCR in the diagnosis of tuberculosis.

AIMS: To evaluate the usefulness of a single-tube nested polymerase chain reaction (PCR) assay in the diagnosis of tuberculosis in 1497 pulmonary and 536 extrapulmonary specimens. METHODS: A single-tube nested PCR, utilising two sets of primers with different melting temperatures (88 degrees C for external primers; 70 degrees C for internal primers) to augment sensitivity and specificity without increasing the risk of amplicon contamination, was evaluated. Specimens were initially tested for the repetitive IS6110 sequences and if negative, retested for the universal 38 kilodalton sequence and for inhibitors. dUTP/Uracil-N-glycosylase and Instagene treatment were used to minimise contamination and the effect of inhibitors, respectively. RESULTS: Using culture as the gold standard, the overall sensitivity of the assay was 89% for pulmonary and 42% for extrapulmonary specimens. Sensitivity varied greatly with respect to sample type (92% for follow up specimens from a chest hospital and 70% for non-follow up specimens from a general hospital). The smear positivity rates were 15% for extrapulmonary specimens, and 69% and 45%, respectively, for follow up and non-follow up specimens from pulmonary sites. Specificity was 99.7%. Inhibitors were present more frequently in extrapulmonary than in pulmonary specimens (13.4% v 2.7%). CONCLUSION: Despite the high sensitivity of the PCR assay for the diagnosis of tuberculosis in pulmonary specimens, it was less effective in the extrapulmonary samples. This is probably because of the lower bacterial load in extrapulmonary specimens, the presence of more inhibitors adversely affecting the PCR assay and the higher volume of specimens used for culture.

Base Sequence↗