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L K Siu

Publications and source records attributed to L K Siu.

At least 19 recordsLinked to original sources
PubMed2006

Capsular serotype K1 or K2, rather than magA and rmpA, is a major virulence determinant for Klebsiella pneumoniae liver abscess in Singapore and Taiwan.

Capsular serotypes, magA, and rmpA have been documented in high prevalence for Klebsiella pneumoniae liver abscess. To investigate the regional difference and the correlation of capsular serotype, magA, and rmpA with virulence, 73 isolates were collected in Singapore and Taiwan. Capsular serotypes were determined by countercurrent immunoelectrophoresis, the presence of magA and rmpA was determined by PCR, and virulence was determined by phagocytosis and mouse inoculation. Isolates from Singapore were similar to those from Taiwan in genomic heterogeneity, prevalence of serotype, and the presence of magA and rmpA. The most common serotype was K1 (34/73; 46.6%), followed by K2 (15/73; 20.5%). magA was restricted to serotype K1. All K1 or K2 isolates and 66.7% (16/24) of isolates that were neither serotype K1 nor serotype K2 (non-K1/K2) carried rmpA. Serotype K1 or K2 isolates demonstrated significantly more phagocytic resistance and virulence than did rmpA-positive and -negative groups of non-K1/K2 isolates. In the non-K1/K2 group, the virulence profiles of rmpA-positive strains from Taiwan and Singapore were different by phagocytosis assay and in the mouse model, indicating that factors other than rmpA contributed to virulence. The characteristics of K. pneumoniae liver abscess in Singapore and Taiwan are similar. Capsular serotype K1 or K2 plays a more important role than magA and rmpA in determining virulence in K. pneumoniae liver abscess.

Animals↗
PubMed2006

Nosocomial liver abscess caused by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae.

A nosocomial pyogenic liver abscess caused by an extended-spectrum beta-lactamase-producing Klebsiella pneumoniae isolate presented in a man with adenocarcinoma of the stomach. The K. pneumoniae strain isolated from blood and liver aspirate cultures after antibiotic therapy for recurrent bacteremia was resistant to all extended-spectrum beta-lactams except imipenem and differed from K. pneumoniae strains causing community-acquired liver abscesses.

Adenocarcinoma↗
PubMed2006

Impaired phagocytosis of capsular serotypes K1 or K2 Klebsiella pneumoniae in type 2 diabetes mellitus patients with poor glycemic control.

CONTEXT: Diabetes mellitus (DM) and capsular serotypes K1 and K2 Klebsiella pneumoniae have been identified as risk factors for liver abscess and complicated endophthalmitis. OBJECTIVE: The objective of this study was to determine whether poor glycemic control contributes to the development of capsular serotype K1 or K2 K. pneumoniae liver abscess. DESIGN AND SETTING: Neutrophil phagocytosis in patients with type 2 DM and nondiabetic controls was compared with isolates from liver abscess. Phagocytic rates of 18 K1/K2 and nine non-K1/K2 K. pneumoniae strains were evaluated by flow cytometry and electron microscopy. PATIENTS OR STUDY PARTICIPANTS: Forty patients with type 2 diabetes, 14 with good glycemic control, 26 with poor glycemic control, and 13 age-matched healthy normal subjects, were studied. MAIN OUTCOME MEASURES: Phagocytic rate of K. pneumoniae was measured. RESULTS: Phagocytosis of serotype K1/K2 isolates by neutrophils from diabetics was significantly less than normal controls (P < 0.01). Further analysis revealed that, in type 2 DM patients with poor glycemic control, phagocytosis of K1/K2 was remarkably impaired at 10 min (25.2 +/- 1.7 vs. 42.4 +/- 1.8%) and persisted until 60 min (51 +/- 1.2 vs. 59.4 +/- 1.4%; P < 0.01), but in type 2 DM patients with good glycemic control were similar at 10 min (38.2 +/- 1.7% vs. 42.4 +/- 1.8%) and at 60 min (57 +/- 0.3% vs. 59.4 +/- 1.4%; P = 0.2). No significant difference in the phagocytosis of non-K1/K2 K. pneumoniae among all subjects was observed. CONCLUSIONS: Poor glycemic control plays a role in impairing neutrophil phagocytosis of K1/K2 K. pneumoniae, but does not significantly affect the phagocytosis of non-K1/K2 K. pneumoniae. This study identifies poor glycemic control as a risk factor for susceptibility to serotype K1/K2 K. pneumoniae liver abscess and complicated endophthalmitis.

Adult↗
PubMed2005

Experience of using convalescent plasma for severe acute respiratory syndrome among healthcare workers in a Taiwan hospital.

OBJECTIVES: To describe the immunological responses and clinical outcome of coronavirus (SARS) infected healthcare workers (HCW) who had been administered with convalescent plasma as a treatment. METHODS: Convalescent plasma (500 mL) was obtained from each of three SARS patients and transfused into the three infected HCW. Donors were blood type O and seronegative for hepatitis B and C, HIV, syphilis and human T-cell lymphotropic virus types I and II (HTLV-I and -II). Serum antibody (IgG) titre was >640. Apharesis was performed with a CS 3000 plus cell separator followed by the forming of the convalescent phase plasma. As part of the routine check with donated plasma, the convalescent plasma was confirmed free of residual SARS-CoV by RT-PCR. Serial serum samples obtained from the recipients of the convalescent plasma were collected to undertake real-time quantitative RT-PCR for SARS-CoV for direct measurement of viral concentration. Specific immunoglobulin IgM and IgG concentrations were titrated using an antigen microarray developed in-house. RESULTS: Viral load dropped from 495 x 10(3), 76 x 10(3) or 650 x 10(3) copies/mL to zero or 1 copy/mL one day after transfusion. Anti-SARS-CoV IgM and IgG also increased in a time-dependent manner following transfusion. All three patients survived. One HCW became pregnant subsequently, delivering 13 months after discharge. Positive anti-SARS-CoV IgG was detected in the newborn. Passive transfer of anti-SARS-CoV antibody from the mother was considered as a possibility. CONCLUSIONS: All infected HCW whose condition had progressed severely and who had failed to respond to the available treatment, survived after transfusion with convalescent plasma.

Adult↗
PubMed2005

Variety of TEM-, SHV-, and CTX-M-type beta-lactamases present in recent clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae from Taiwan.

A total of 171 hospitals' isolates of E. coli, K. pneumoniae, and E. cloacae with a minimum inhibitory concentration (MIC) of > or =2 microg/ml for ceftazidime or cefotaxime were evaluated for the production of beta-lactamases. PCR amplification with specific primers for the bla (SHV), bla (TEM), and bla (CTX) genes revealed that a total of 53, 81, and 43 of these genes were amplified, respectively. Sequencing results confirmed that TEM-1, CTX-M-3 and -14, SHV-1, -5, -11, -12, and -33, OXY-1a, and LEN-1 were presented among these isolates. No specific large cluster of isolates carried the same beta-lactamases, indicating the wide diversity of the collected strains. Plasmid spread between E. coli and K. pneumoniae was identified in few isolates. Combinations of TEM, SHV, and CTX beta-lactamase genes, including extended-spectrum beta-lactamase genes, were observed in all three species.

Enterobacteriaceae↗
PubMed2005

Novel SHV-derived extended-spectrum beta-lactamase, SHV-57, that confers resistance to ceftazidime but not cefazolin.

A new SHV-derived extended-spectrum beta-lactamase, SHV-57, that confers high-level resistance to ceftazidime but not cefotaxime or cefazolin was identified from a national surveillance study conducted in Taiwan in 1998. An Escherichia coli isolate resistant to ampicillin, cephalothin, and ceftazidime but sensitive to cefoxitin, ceftriaxone, cefotaxime, imipenem, and a narrow-spectrum cephem (cefazolin) was isolated from the urine of a patient treated with beta-lactam antibiotics. Resistance to beta-lactams was conjugatively transferred with a plasmid of about 50 kbp. The pI of this enzyme was 8.3. The sequence of the gene was determined, and the open reading frame of the gene was found to consist of 861 bases (GenBank accession number AY223863). Kinetic parameters showed that SHV-57 had a poor affinity to cefazolin. The K(m) value toward cefazolin (5.57 x 10(3) muM) was extremely high in comparison to those toward ceftazidime (30.9 muM) and penicillin G (67 muM), indicating its low affinity to cefazolin. Although the K(m) value of the beta-lactamase inhibitor was too high for the study of catalytic activity (k(cat)), indicating the low k(cat) of SHV-57, the SHV-57 carrier was highly susceptible to a beta-lactam-beta-lactamase inhibitor combination. Comparison of the three-dimensional molecular model of SHV-57 with that of the SHV-1 beta-lactamase suggests that the substitution of arginine for leucine-169 in the Omega loop is important for the substrate specificity.

Cefazolin↗
PubMed2005

Risk factors and molecular analysis of community methicillin-resistant Staphylococcus aureus carriage.

A total of 1,838 subjects from the community and 393 subjects from health care-related facilities in Taiwan were evaluated for the prevalence of nasal Staphylococcus aureus colonization and to identify risk factors associated with S. aureus and methicillin-resistant S. aureus (MRSA) colonization. Among the community subjects, 3.5% had nasal MRSA colonization. Subjects from health care-related facilities had a lower S. aureus colonization rate (19.1%) than community subjects (25.2%) but had a significantly higher rate of colonization with MRSA (7.63%). Age (P < 0.001) was a significant risk factor for S. aureus colonization, with subjects under age 20 years or between 71 and 80 years showing higher rates of colonization. Recent gastrointestinal disease (P = 0.011) and hospital admission (P = 0.026) were risk factors for nasal MRSA colonization. Comparison of hospital MRSA isolates with the colonization strains by staphylococcal cassette chromosome mec (SCCmec) gene typing and pulsed-field gel electrophoresis (PFGE) typing revealed that most MRSA strains carried in the community were SCCmec type IV and that most clinical hospital isolates were type III, while health care facility-related carriage isolates were mainly SCCmec type III and type IV. Two new variant SCCmec types were identified. Six clusters of PFGE patterns were distinguished: two mainly comprised health care facility-related MRSA strains, three mainly comprised community MRSA strains, and one comprised mixed community and health care facility-related MRSA strains. In conclusion, a high prevalence of MRSA colonization was observed among people with no relationship to the hospital setting. The high level of multiple-drug resistance among community MRSA strains in association with the previously reported excessive use of antibiotics in Taiwan highlights the importance of the problem of antibiotic selective pressure. Our results indicate that both the clonal spread of MRSA and the transmission of hospital isolates contribute to the high MRSA burden in the community.

Adolescent↗
PubMed2005

First report of Salmonella enterica serotype panama meningitis associated with consumption of contaminated breast milk by a neonate.

Salmonella enterica serotype Panama is capable of causing severe infection in children and is often transmitted via contaminated food. Here, we present the first documented case of serotype Panama infection that was acquired through the consumption of contaminated breast milk. The mother excreted the organism asymptomatically for at least 2 weeks.

Breast Feeding↗
PubMed2004

Molecular and epidemiologic analysis of a county-wide outbreak caused by Salmonella enterica subsp. enterica serovar Enteritidis traced to a bakery.

BACKGROUND: An increase in the number of attendees due to acute gastroenteritis and fever was noted at one hospital emergency room in Taiwan over a seven-day period from July to August, 2001. Molecular and epidemiological surveys were performed to trace the possible source of infection. METHODS: An epidemiological investigation was undertaken to determine the cause of the outbreak. Stool and blood samples were collected according to standard protocols per Center for Disease Control, Taiwan. Typing of the Salmonella isolates from stool, blood, and food samples was performed with serotyping, antibiotypes, and pulsed field gel electrophoresis (PFGE) following XbaI restriction enzyme digestion. RESULTS: Comparison of the number of patients with and without acute gastroenteritis (506 and 4467, respectively) during the six weeks before the outbreak week revealed a significant increase in the number of patients during the outbreak week (162 and 942, respectively) (relative risk (RR): 1.44, 95% confidence interval (CI): 1.22-1.70, P value < 0.001). During the week of the outbreak, 34 of 162 patients with gastroenteritis were positive for Salmonella, and 28 of these 34 cases reported eating the same kind of bread. In total, 28 of 34 patients who ate this bread were positive for salmonella compared to only 6 of 128 people who did not eat this bread (RR: 17.6, 95%CI 7.9-39.0, P < 0.001). These breads were produced by the same bakery and were distributed to six different traditional Chinese markets., Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) was isolated from the stool samples of 28 of 32 individuals and from a recalled bread sample. All S. Enteritidis isolates were of the same antibiogram. PFGE typing revealed that all except two of the clinical isolates and the bread isolates were of the same DNA macrorestriction pattern. CONCLUSIONS: The egg-covered bread contaminated with S. Enteritidis was confirmed as the vehicle of infection. Alertness in the emergency room, surveillance by the microbiology laboratory, prompt and thorough investigation to trace the source of outbreaks, and institution of appropriate control measures provide effective control of community outbreaks.

Adolescent↗
PubMed2004

Epidemiological typing of community-acquired methicillin-resistant Staphylococcus aureus isolates from children in Taiwan.

BACKGROUND: A 1400-bed tertiary medical center in northern Taiwan was used to conduct an epidemiological study of children hospitalized with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection during a 5-year period. METHODS: Nineteen previously healthy children with predominantly skin and soft-tissue CA-MRSA infections were enrolled into the study. Seventeen CA-MRSA isolates were examined for antimicrobial susceptibility and molecular typing. RESULTS: A comparison of our results with the reported resistance rates among CA-MRSA isolates from other countries showed uniformly high macrolide resistance (100%). Of the 17 MRSA isolates in our study, all had the macrolide-lincosamide-streptogramin-constitutive phenotype and the ermB gene. Moreover, on the basis of molecular typing results, 11 (65%) of 17 CA-MRSA isolates were genetically related (as determined by pulsed-field gel electrophoresis), and multilocus sequence typing revealed a sequence type of 59 in all isolates. Staphylococcal toxin genes lukS-PV and lukF-PV were detected in all isolates. However, staphylococcal cassette chromosome mec type IV was only detected in 3 (17.6%) of 17 isolates; the remaining 14 isolates were untypeable. CONCLUSIONS: Analysis of our data suggests the predominance of a single endemic CA-MRSA strain with high macrolide resistance in our community. Clinical improvement with incision and drainage was noted for most patients, despite treatment with an ineffective antibiotic, so the need for a change in treatment guidelines should be addressed.

Bacterial Proteins↗
PubMed2004

Mutations of the rpoB gene in rifampicin-resistant Streptococcus pneumoniae in Taiwan.

OBJECTIVE: To determine the mechanism of rifampicin resistance in Streptococcus pneumoniae in Taiwan. METHODS: Rifampicin resistance was investigated with respect to the rpoB gene in 23 invasive S. pneumoniae isolates collected from 1996 to 2001. PCR and molecular typing were used for genetic and epidemiological analyses. Transformation was used to determine the functional gene for resistance. RESULTS: Twenty-two of 23 isolates carried at least one mutation at either cluster I or III of rpoB; the most frequent mutation found in 21 isolates (91%) was histidine (H499) to asparagine or tyrosine at position 499, followed by isoleucine to valine (I624V) at position 624 in 16 isolates (70%), tyrosine to phenylalanine (Y589F) at position 589 in 14 isolates (60.9%) and isoleucine to valine (I608V) at position 608 in 13 isolates (56.5%). Less-frequent mutations were also identified: D489V, R597F, N623E, N623S, N669D, Q671K, Y674F and A683V. High-level rifampicin resistance was observed in isolates with a mutation at position 499 or 489. Mutations other than at position 499 or 489 played little role in or had no relation to rifampicin resistance. No dominant epidemic strain was observed with ribotyping, multilocus sequence typing, or serotyping. CONCLUSIONS: Rifampicin resistance among multidrug-resistant S. pneumoniae in Taiwan was mostly caused by rpoB mutations.

Amino Acid Substitution↗
PubMed2004

High prevalence of phagocytic-resistant capsular serotypes of Klebsiella pneumoniae in liver abscess.

To better understand the role of capsular polysaccharide (CPS) K1 or K2 in Klebsiella pneumoniae liver abscess as well as the development of metastasis to eye, neutrophil phagocytosis of 70 CPS isolates including K1 (n = 23)/K2 (n = 10), non-K1/K2 (n = 37) was evaluated by flow cytometry, fluorescence imaging, and electron microscopy. K1/K2 isolates were significantly more resistant to phagocytosis (P < 0.0001) than non-K1/K2 isolates and displayed increased resistance to intracellular killing. Although mucoid phenotype (M-type) K1/K2 isolates were significantly more resistant to phagocytosis (P = 0.0029) than M-type non-K1/K2, no significant difference in the phagocytosis rate was observed between K1/K2 isolates with M-type and non-M-type (P = 0.0924). Mucoidy is an associated factor that was predominant in K1/K2 isolates, but which itself is not an independent influence on phagocytic resistance. The K1/K2 CPS proved significantly more resistant to phagocytosis than non-K1/K2 CPS in liver abscess isolates (P < 0.0001) and non-abscess isolates (P = 0.0001), suggesting that K1/K2 isolates were generally more virulent in both liver abscess and in non-liver abscess conditions. These findings indicate that resistance of CPS K1 or K2 K. pneumoniae to phagocytosis and intracellular killing presumably contributes to their high prevalence in liver abscess and uniquely in endophthalmitis.

Antigens, Bacterial↗
PubMed2004

Rapid creation of a temporary isolation ward for patients with severe acute respiratory syndrome in Taiwan.

OBJECTIVES: To rapidly establish a temporary isolation ward to handle an unexpected sudden outbreak of severe acute respiratory syndrome (SARS) and to evaluate the implementation of exposure control measures by healthcare workers (HCWs) for SARS patients. DESIGN: Rapid creation of 60 relatively negative pressure isolation rooms for 196 suspected SARS patients transferred from 19 hospitals and daily temperature recordings of 180 volunteer HCWs from 6 medical centers. SETTING: A military hospital. RESULTS: Of the 196 patients, 34 (17.3%) met the World Health Organization criteria for probable SARS with positive results of serologic testing for SARS-associated coronavirus (SARS-CoV), reverse transcriptase polymerase chain reaction (RT-PCR) from nasopharyngeal or throat swabs for SARS-CoV, or both. Seventy-four patients had suspected SARS based on unprotected exposure to SARS patients; three of them had positive results on RT-PCR but negative serologic results. The remaining 88 patients did not meet the criteria for a probable or suspected SARS diagnosis. Of the 34 patients with probable SARS, 13 were transferred to medical centers to receive mechanical ventilation due to rapid deterioration of chest x-ray results, and three patients died of SARS despite intensive therapy in medical centers. During the study period, one nurse developed probable SARS due to violation of infection control measures, but there was no evidence of cross-transmission to other HCWs. CONCLUSIONS: Despite the use of full personal protection equipment, the facility failed to totally prevent exposures of HCWs to SARS but minimized the risk of nosocomial transmission. Better training and improvements in infection control infrastructure may limit the impact of SARS.

Disease Outbreaks↗
PubMed2004

Vancomycin-resistant enterococcus (VRE) carriage and infection in intensive care units.

From July, 1997, through December, 2001, patients who were admitted to intensive care units (ICUs) were enrolled in the study of vancomycin resistance enterococcus (VRE) colonization. Among 4,538 patients admitted to the ICUs, 363 (8.0%) patients were found to have positive culture of VRE at the day of admission to the ICUs and 453 (10.0%) of patients were negative to the first day of admission but became colonized with VRE during the stay in ICU. Among 816 patients, 9 (1.1%) with VRE isolated from sterile sites were selected for further analysis. Pulsed-field gel electrophoresis (PFGE) revealed a total of four PFGE banding patterns in the colonized and infected Enterococcus faecium isolates. Six of nine 9 were found to have an identical PFGE type Ia, suggesting the circulation of an endemic strain. All of these type Ia isolates also contained two potential virulence genes, the esp and hly genes and were first identified in Asia. After the further typing of 540 isolates that were randomly selected from each month, the endemic strain was not identified before the first patient was colonized and infected with this strain in November, 1998, but was isolated from other ICU patients during each month thereafter throughout the remainder of the study period. Although colonization of VRE is the first step toward infection, a low infection rate was observed, except in patients with prolonged hospitalization and severe illness. Use of the isolation room and reminders regarding hand hygiene failed to prevent the circulation of endemic strain. Thus, the SHEA guideline (Muto et al., Infect. Control Hosp. Epidemiol. 2003;24:362-386) for preventing nosocomial transmission of VRE should be enforced.

Bacterial Proteins↗
PubMed2004

Variable resistance patterns of integron-associated multidrug-resistant Acinetobacter baumannii isolates in a surgical intensive care unit.

Between 1998 and 2000, we characterized 91 nosocomial isolates of Acinetobacter baumannii by antibiotyping and genotyping. A total of 25 ribotypes were obtained among these 91 isolates. When the isolates from surgical intensive care units (ICUs) and other wards were compared, multiresistant A. baumannii isolates with the same ribotype 25 (R-25) were significantly more prevalent in nosocomial infections among the surgical patients. Further subtyping of the strains by pulsed-field gel electrophoresis confirmed that strains of the same ribotype in surgical ICUs and a few isolates from other wards were identical or clonally related. Different antibiotic resistance profiles were observed among these R-25 isolates. All R-25 isolates contained intI1 integrase, and two clusters of integron cassettes were found. These clusters of cassettes were encoded by an open reading frame (ORF) of -5'CS-aac(3)Ia-aadA1a-unknown or f-3'CS or 5'CS-aacA4-aadA1-catB8-3'CS, indicating the involvement of different resistant genes. Two isolates contained bla (IMP-1), which was acquired from a conjugatively transferable plasmid and did not involve integron-associated resistance. In conclusion, an epidemic of nosocomial infections associated with A. baumannii strains that have different resistance profiles was identified. Resistance profiles can change by a combination of plasmid- and integron-associated acquisition, especially in a unit with high antibiotic selective pressures. Infectious control personnel should be alert to the change in resistance profiles during routine monitoring.

Acinetobacter Infections↗
PubMed2003

In vitro susceptibility of six fluoroquinolones against invasive Streptococcus pneumoniae isolated from 1996 to 2001 in Taiwan.

A total of 331 invasive nonduplicated Streptococcus pneumoniae isolates from three sampling periods during 1996 to 2001 were tested for susceptibility to recently developed fluoroquinolones. Five major serotypes, 23F, 6B, 14, 19F, and 3, were frequently encountered in this collection. Penicillin nonsusceptible isolates constituted 52.9% from 1996 to 1997, 61.6% from 1998 to 1999, and 60.0% from 2000 to 2001. Fifty-seven percent of the isolates were susceptible to cefotaxime, 56.5% to ceftriaxone, 54.1% to cefepime, and 52.6% to cefuroxime. Macrolide-susceptible isolates constituted less than 14% of the total sample, and no vancomycin-resistant isolates were detected. For fluoroquinolones, MIC90 was lowest for gemifloxacin (MIC90 = < or = 0.12 microg/ml), followed by moxifloxacin (MIC90 = 0.25 microg/ml), gatifloxacin (MIC90 = 0.5 microg/ml), sparfloxacin (MIC90 = 0.5 microg/ml), levofloxacin (MIC90 = 1 microg/ml), and ciprofloxacin (MIC90 = 2 microg/ml). All isolates were susceptible to sparfloxacin, levofloxacin, gatifloxacin, and gemifloxacin apart from one isolate (0.3%), which was simultaneously resistant to sparfloxacin, levofloxacin, and gatifloxacin. Mutations at the positions S81F of GyrA and D435N and I460V of ParC were detected for this multiple drug resistant isolate. The in vitro results suggest that recently developed fluoroquinolones are very effective against invasive S. pneumoniae isolates in Taiwan. Nevertheless, emerging fluoroquinolone resistance should be acknowledged and clinicians alerted. Surveillance should be carried out to monitor any changes in antibiotic resistance of S. pneumoniae.

Adult↗