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Biomedical subjects

K Y Yuen

Publications and source records attributed to K Y Yuen.

At least 145 records · Page 8Linked to original sources
PubMed1999

Liver transplantation in infants.

PURPOSE: In view of the earlier reports that children below 1 year of age constitute a high-risk group for liver transplantation, the authors reviewed their experience in performing orthotopic liver transplantation in this age group. METHODS: The records of 9 children aged less than 1 year who underwent 6 living-related liver transplants and 3 reduced-size liver transplants between December 1993 and June 1997 were reviewed. RESULTS: Five reexplorations were required for 3 children who had 1 or more of the following early complications: bleeding from hepatic vein to inferior vena cava anastomosis (n = 1), right hepatic vein stump bleeding (n = 1), intraabdominal hematoma (n = 2), jejuno-jejunostomy leakage (n = 1), and colonic perforation (n = 1). Late complications include stricture at the biliary-enteric anastomosis requiring percutaneous balloon dilatation (n = 3) and hepatitis of undetermined etiology requiring retransplantation (n = 1). There was no hepatic artery thrombosis despite the small arteries available for anastomosis. Follow-up ranged from 19 to 61 months (mean, 40 months). Patient survival rate was 100%, and graft survival with good liver function was 89%. All living donors, 2 fathers and 4 mothers, are well. CONCLUSIONS: Liver transplantation in infants less than 1 year of age is technically demanding but feasible and still can be performed with a good outcome. Age alone (under 1 year) should not be considered as a contraindication for liver transplantation.

Age Factors↗
PubMed1999

Susceptibility testing of Clostridium difficile against metronidazole and vancomycin by disk diffusion and Etest.

A prospective study on the susceptibility of Clostridium difficile to metronidazole and vancomycin using the Etest and disk diffusion test was performed over a 6-month period. One hundred strains were tested; one strain was highly resistant to metronidazole (MIC = 64 micrograms/mL). The zone size of inhibition by the disk diffusion test correlated with the MIC as determined by the Etest (regression coefficient = -0.043 for metronidazole and -0.044 for vancomycin, p < 0.001 for both antibiotics). However, the correlation coefficient was low for both metronidazole (r = 0.574) and vancomycin (r = 0.473); hence the zone of inhibition by disk diffusion test could not predict the MIC satisfactorily. Metronidazole is still the first-line antibiotic for the treatment of C. difficile-associated diarrhea because the incidence of metronidazole resistant strains remains very low. However, the efficacy of metronidazole in the treatment of infections attributable to isolates with high-level metronidazole resistance may be compromised because the fecal concentration of metronidazole is relatively low when compared with the MIC values of the less susceptible strains. Oral vancomycin is the drug of choice under such circumstances, as its fecal concentration is much higher than that of metronidazole.

Anti-Bacterial Agents↗
PubMed1999

Acinetobacter bacteremia in Hong Kong: prospective study and review.

The epidemiological characteristics of 18 patients with acinetobacter bacteremia were analyzed. Patients (mean age, 55.5 years) developed bacteremia after an average of 14.1 days of hospitalization. Fifteen of 16 patients survived bacteremia caused by Acinetobacter baumannii. Cultures of blood from the remaining two patients yielded Acinetobacter lwoffii. Most patients (78%) resided in the general ward, while four patients (22%) were under intensive care. Genotyping by arbitrarily primed polymerase chain reaction analysis and the temporal sequence of isolation were more useful than phenotyping by antimicrobial susceptibility in the determination of the source of bacteremia, and the intravascular catheter was the leading infection source (39% of cases). The possibility of an association of glucose with the pathogenesis of acinetobacter infection was raised.

Acinetobacter↗
PubMed1999

Bacteremia caused by staphylococci with inducible vancomycin heteroresistance.

The clinical significance of bacteremia due to vancomycin-heteroresistant staphylococci and a rapid laboratory screening method were examined; 203 strains of staphylococci isolated from patients with clinically significant bacteremia were screened by the disk-agar method with use of vancomycin-salt agar to demonstrate satellitism around an aztreonam disk as well as by conventional population screening. Eighteen isolates (three Staphylococcus aureus and 15 coagulase-negative staphylococci) were shown to be heteroresistant to vancomycin. A case-control clinical study showed that the interval between admission and bacteremia, admission to the intensive care unit, prior use of vancomycin and/or beta-lactams, and isolation of methicillin-resistant staphylococci were significantly more common among patients with bacteremia due to staphylococci with heteroresistance to vancomycin; these patients had an overall mortality of 44.4%. The use of vancomycin and admission to the intensive care unit were independently significant risk factors on multivariate analysis. Vancomycin heteroresistance is inducible by salt and beta-lactams. Indiscriminate sequential use of beta-lactams and glycopeptides may facilitate the emergence of glycopeptide resistance.

Adolescent↗
PubMed1999

Antibiotics modulate vaccine-induced humoral immune response.

The effects of antibiotics on the antigen-specific humoral immune response are not known. Macrolides, tetracyclines, and beta-lactams are commonly prescribed antibiotics. The first two are known to have immunomodulatory activities. The effects of clarithromycin, doxycycline, and ampicillin on the primary and secondary antibody responses to tetanus toxoid, a pneumococcal polysaccharide vaccine, a hepatitis B virus surface antigen (HBsAg) vaccine, and live attenuated Salmonella typhi (Ty21a) were investigated using a mouse model. For the mice receiving the tetanus toxoid, the immunoglobulin M (IgM) level of the clarithromycin group at day 7 was significantly lower than the corresponding antibody level of the normal saline (NS) group. For the mice receiving the pneumococcal polysaccharide vaccine, the total antibody and IgM levels of the clarithromycin group and the IgM level of the doxycycline group at day 7 were significantly lower than the corresponding antibody levels of the ampicillin and NS groups. For the mice receiving the HBsAg vaccine, the IgM level of the doxycycline group at day 7 was significantly lower than the corresponding antibody levels of the clarithromycin and NS groups, while the IgM level of the clarithromycin group at day 28 was significantly lower than the corresponding antibody levels of the doxycycline, ampicillin, and NS groups. For the mice receiving all three vaccines, there were no statistically significant differences between any of the antibody levels of the ampicillin group and the corresponding antibody levels of the NS group. For the mice receiving Ty21a, the total antibody levels of the ampicillin group at days 7 and 21 were significantly higher than the corresponding antibody levels of the NS group. Moreover, the IgM levels of the clarithromycin, doxycycline, and ampicillin groups at days 7 and 21 were significantly higher than the corresponding antibody levels of the NS group. Furthermore, the total antibody level of the ampicillin group at day 21 was significantly higher than the corresponding antibody level of the doxycycline group. For all four vaccines, there were no statistically significant differences among the serum levels of interleukin-10 and gamma interferon for the mice treated with the various antibiotics. We conclude that clarithromycin and doxycycline, but not ampicillin, suppress the antibody responses of mice to T-cell-dependent and T-cell-independent antigens, whereas all three antibiotics enhance the antibody response to live attenuated mucosal bacterial vaccines.

Ampicillin↗
PubMed1999

Detection of cell wall mannoprotein Mp1p in culture supernatants of Penicillium marneffei and in sera of penicilliosis patients.

Mannoproteins are important and abundant structural components of fungal cell walls. The MP1 gene encodes a cell wall mannoprotein of the pathogenic fungus Penicillium marneffei. In the present study, we show that Mp1p is secreted into the cell culture supernatant at a level that can be detected by Western blotting. A sensitive enzyme-linked immunosorbent assay (ELISA) developed with antibodies against Mp1p was capable of detecting this protein from the cell culture supernatant of P. marneffei at 10(4) cells/ml. The anti-Mp1p antibody is specific since it fails to react with any protein-form lysates of Candida albicans, Histoplasma capsulatum, or Cryptococcus neoformans by Western blotting. In addition, this Mp1p antigen-based ELISA is also specific for P. marneffei since the cell culture supernatants of the other three fungi gave negative results. Finally, a clinical evaluation of sera from penicilliosis patients indicates that 17 of 26 (65%) patients are Mp1p antigen test positive. Furthermore, a Mp1p antibody test was performed with these serum specimens. The combined antibody and antigen tests for P. marneffei carry a sensitive of 88% (23 of 26), with a positive predictive value of 100% and a negative predictive value of 96%. The specificities of the tests are high since none of the 85 control sera was positive by either test.

Antibodies, Fungal↗
PubMed1999

Reduction of platelet transfusion- associated sepsis by short-term bacterial culture.

BACKGROUND AND OBJECTIVES: There is as yet no suitable routine laboratory test for a blood transfusion service to detect bacterial contamination in platelets. This study evaluates the effectiveness and the applicability of short-term bacterial culture for such a purpose. MATERIALS AND METHODS: Samples from 5-unit platelet pools were inoculated into an aerobic culture bottle, then monitored for 48 h at 35 degrees C in an automated monitoring and detection system. RESULTS: 26,210 whole-blood-derived platelet components were tested, of which 14 (0.053%) platelet units were found to be contaminated. In addition, nine of the associated red cell units and 4 fresh-frozen plasma units grew the same organisms on culture. CONCLUSION: Short-duration bacterial culture by an automated system is effective and suitable for routine screening in a regional transfusion center.

Colony-Forming Units Assay↗
PubMed1999

A pilot study of low-dose erythromycin in bronchiectasis.

Patients with bronchiectasis suffer from sputum production, recurrent exacerbations, and progressive airway destruction. Erythromycin is effective in diffuse panbronchiolitis, another suppurative airway disorder, although its efficacy is unknown in idiopathic bronchiectasis. A double-blind placebo-controlled study was therefore conducted to evaluate the effects of 8-week administration of low dose erythromycin (500 mg b.i.d.) in steady-state idiopathic bronchiectasis. Patients in the erythromycin group (n=11, 8 female, mean age 50+/-15 yrs), but not the placebo group (n=10, 8 female, mean age 59+/-16 yrs) had significantly improved forced expiratory volume in one second, forced vital capacity and 24-h sputum volume after 8 weeks (p<0.05). There was no parallel improvement in sputum pathogens, leukocytes, interleukin (IL)-1alpha and IL-8, tumour necrosis factor-alpha, or leukotriene B4. The results of this pilot study show that low-dose erythromycin improves lung function and sputum volume in bronchiectasis. Further studies are indicated to evaluate the efficacy of long-term erythromycin therapy in bronchiectasis.

Anti-Bacterial Agents↗
PubMed1998

Clinical features and rapid viral diagnosis of human disease associated with avian influenza A H5N1 virus.

BACKGROUND: Human infection with an avian influenza A virus (subtype H5N1) was reported recently in Hong Kong. We describe the clinical presentation of the first 12 patients and options for rapid viral diagnosis. METHODS: Case notes of 12 patients with virus-culture-confirmed influenza A H5N1 infection were analysed. The clinical presentation and risk factors associated with severe disease were defined and the results of methods for rapid virus diagnosis were compared. FINDINGS: Patients ranged from 1 to 60 years of age. Clinical presentation was that of an influenza-like illness with evidence of pneumonia in seven patients. All seven patients older than 13 years had severe disease (four deaths), whereas children 5 years or younger had mild symptoms with the exception of one who died with Reye's syndrome associated with intake of aspirin. Gastrointestinal manifestations, raised liver enzymes, renal failure unrelated to rhabdomyolysis, and pancytopenia were unusually prominent. Factors associated with severe disease included older age, delay in hospitalisation, lower-respiratory-tract involvement, and a low total peripheral white blood cell count or lymphopenia at admission. An H5-specific reverse-transcription PCR assay (RT-PCR) was useful for rapid detection of virus directly in respiratory specimens. A commercially available enzyme immunoassay was more sensitive than direct immunofluorescence for rapid viral diagnosis. Direct immunofluorescence with an H5-specific monoclonal antibody pool was useful for rapid exclusion of H5-subtype infection. INTERPRETATION: Avian Influenza A H5N1 virus causes human influenza-like illness with a high rate of complications in adults admitted to hospital. Rapid H5-subtype-specific laboratory diagnosis can be made by RT-PCR applied directly to clinical specimens.

Adult↗
PubMed1998

Fungal endocarditis in bone marrow transplantation: case report and review of literature.

We report a case of fungal endocarditis due to Aspergillus terreus in a leukaemia patient who received a bone marrow allograft from a matched unrelated donor. He presented with persistent fever. microangiopathic haemolytic anaemia but there was no cardiac signs and symptoms. He died despite intravenous amphotericin B. Review of the English literature showed five other patients with fungal endocarditis in the setting of bone marrow transplantation and revealed the same features of difficult diagnosis and poor outcome.

Adult↗
PubMed1998

Clinical significance of alimentary tract microbes in bone marrow transplant recipients.

A prospective study on the microbes isolated from the alimentary tract in 120 bone marrow transplant (BMT) recipients (1991-1993) was undertaken to define the spectrum of organisms isolated under antimicrobial prophylaxis, their temporal sequence of emergence, and the associated morbidity and mortality. Clostridium difficile (n = 20), isolated in the pre-engraftment and early post-engraftment periods (day 2-45 post-BMT), was the most common microbe recovered from stool of patients with diarrhea. In contrast to previous reports, no significant difference in mortality was observed between patients with and without C. difficile isolated in stool. Two patients had neutropenic ileocecitis with concomitant bacteremia due to Escherichia coli and Klebsiella pneumoniae. One patient was found to have astrovirus gastroenteritis (day 7), and Giardia lamblia was recovered from the stool of another (day -7). Heavy growth of Staphylococcus aureus from direct smear-positive specimens was found from the upper airway of two patients with severe mucositis and complete dysphagia (day 12 and 23). Salmonella spp. of groups B and E were found in the stool of five asymptomatic patients at the time of conditioning. No specific organisms was recovered from the endoscopic brushing of two patients with lower end esophagitis, three patients with upper gastrointestinal bleeding, and three patients with perirectal cellulitis. During the post-engraftment period, five patients had documented cytomegalovirus gastroenterocolitis (days 34-97), one had Mycobacterium chelonae colitis (day 70), and another had nodular gastritis due to Acremonium falciforme (day 270). Overall, only 28% of patients with alimentary tract symptoms/syndrome had specific pathogens isolated from clinical specimens. Differentiation of the causation of alimentary tract symptoms was often difficult because noninfectious complications such as conditioning toxicity, graft-versus-host disease, and its treatment often caused alimentary tract symptoms in addition to predisposed BMT patient to infection. The reluctance of obtaining tissue biopsy for ascertaining the importance of those potential alimentary tract pathogens often dictate the use of empirical treatment.

Adolescent↗
PubMed1998

Unique risk factors for bacteraemia in allogeneic bone marrow transplant recipients before and after engraftment.

A study of the risk factors associated with bacteraemia in 191 allogeneic bone marrow transplant (BMT) recipients (1991-1996) was performed. In contrast to risk factors commonly cited for cancer chemotherapy, mucositis, degree of conditioning toxicity of the gut and lungs, duration of neutropenia, and severity of neutropenia and monocytopenia were not associated with bacteraemia in the pre-engraftment period, during which the only significant risk factor was late stage underlying disease (P < 0.05). After engraftment, Hickman catheter infection, and severe acute and chronic graft-versus-host disease (GVHD) were found to be independently associated with bacteraemia by multivariate analysis (P < 0.001, <0.05 and <0.05, respectively). This might be explained by intense antimicrobial prophylaxis, early empirical treatment, and non-routine use of haemopoietic growth factors. No significant difference in mortality was detected between bacteraemic and non-bacteraemic patients in both periods. Allogeneic BMT recipients are therefore a group of patients distinct from other cancer patients receiving chemotherapy at risk of developing bacteraemia. The study findings prompt consideration of a management protocol incorporating early and routine use of haemopoietic growth factors before engraftment in high-risk patients with late stage underlying malignancies, routine antimicrobial prophylaxis for acute GVHD with intense immunosuppression, and intravenous immunoglobulin therapy for chronic GVHD. Further cost-benefit analyses are warranted.

Adolescent↗
PubMed1998

Simultaneous Aspergillus fischeri and Herpes simplex pneumonia in a patient with multiple myeloma.

A patient with light chain myeloma complicated by simultaneous Herpes simplex and Aspergillus fischeri pneumonia is presented. Microscopic examination of her bronchoalveolar specimen showed bronchial cells with cytopathic effects and numerous cleistotheca, the sexual reproductive structures of Aspergillus. Culture was positive for Herpes simplex virus and Aspergillus fischeri. The initial partial response to amphotericin B followed by complete clinical response with addition of intravenous acyclovir emphasized the importance of recognition of simultaneous infection by these 2 pathogens. This is the first report of identifying cleistotheca in the bronchoalveolar lavage specimen.

Aspergillosis↗
PubMed1998

Necrotizing fasciitis due to Vibrio alginolyticus following an injury inflicted by a stingray.

We describe the case of a patient with necrotizing fasciitis due to Vibrio alginolyticus in a patient with cirrhosis following an injury inflicted by a stingray. The patient was successfully treated with aggressive surgical debridement and a combination of ciprofloxacin and amoxicillin-clavulanate. Cases of invasive V. alginolyticus reported in the literature were reviewed.

Adult↗
PubMed1998

Inpatient emergencies encountered by an infectious disease consultative service.

The spectrum of infectious disease (ID) emergencies in hospitalized patients was assessed in a prospective study of 3,626 inpatient ID consultations in a 1,350-bed teaching hospital. ID emergencies, defined by a need or anticipated need for advanced life support or by irreversible organ damage leading to permanent functional loss, were encountered in 175 patients. Infections of the central nervous system (26.3%), cardiovascular system (14.9%), alimentary system (13.1%), and lower respiratory tract (7.4%) and adverse reactions to antimicrobial agents (7.4%) were most common. In 18.9% of the cases, the referring clinicians were unaware of the emergency at the time of referral. Drug reactions (46.1%), severe alimentary and peritoneal infections (32.0%), upper respiratory tract infections (28.6%), and skin and soft-tissue infections (27.3%) were most frequently missed. The emergency ID conditions were not recognized because they had an atypical presentation (51.5%), were not commonly seen in the referring specialty (24.2%), were due to rare organisms (15.2%), or had unusual anatomical sites of involvement (9.1%). A close liaison between clinicians and the ID team is crucial for recognition of ID emergencies at their early stages so that appropriate investigations and management can be instituted expediently, before the occurrence of irreversible damage.

Adult↗