Tyen-Po Chen

Risk Factors and Molecular Analysis of Community Methicillin-Resistant Staphylococcus aureus Carriage

ABSTRACT 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.

Diversity of carbapenem resistance mechanisms in Acinetobacter baumannii from a Taiwan hospital: spread of plasmid-borne OXA-72 carbapenemase.

OBJECTIVES We investigated the molecular epidemiology of carbapenem-resistant Acinetobacter baumannii from a Taiwanese hospital and determined the mechanisms responsible for resistance. METHODS Ninety-two consecutive meropenem-resistant A. baumannii isolates collected between January 2005 and June 2007 were screened for genes encoding OXA carbapenemases, metallo-beta-lactamases and for the carO gene encoding an outer membrane protein. PFGE was used to define clonal relatedness. PCR mapping was used to examine the linkage of insertion sequences and bla(OXA) genes. Southern hybridization of plasmid extracts and I-CeuI-restricted chromosomal DNA was used to locate bla(OXA-24-like) genes. Sequences of selected bla(OXA-24-like) and carO genes were determined and loss of CarO expression was confirmed by SDS-PAGE. RESULTS Most (70/92, 76%) isolates belonged to one of three PFGE pulsotypes, indicating clonal spread. Fifty-nine isolates, including the majority of those of pulsotypes I and III, produced OXA-72 carbapenemase. The bla(OXA-72) gene was located on a 54 kb plasmid in selected isolates. Thirty-three (36%) isolates, including all 16 of pulsotype II, had ISAba1 preceding the bla(OXA-51-like) gene, promoting its expression. In addition to OXA-72 carbapenemase, two pulsotype I and three pulsotype III isolates did not produce CarO protein as the carO gene was disrupted by insertion of an ISAba1 element. Two isolates of a minor pulsotype had a bla(OXA-58-like) gene and a single PFGE-unique isolate had a bla(OXA-23-like) gene. CONCLUSIONS Although diverse mechanisms were identified, production of OXA-72 carbapenemase was the most common mechanism of carbapenem resistance in A. baumannii from this Taiwanese hospital. The plasmidic location of the gene had facilitated its spread to multiple strains.

Mutation analysis of PTEN/MMAC1 in acute myeloid leukemia

Recently, a putative tumor suppressor gene, PTEN/MMAC1, has been identified at chromosome 10q23.3, which encodes a 403 amino acid dual‐specificity phosphatase containing a region of homology to tensin and auxillin. Somatic mutations of the PTEN/MMAC1 gene have been identified in a number of cancer cell lines and primary cancers. Mutations in PTEN/MMAC1 are most frequently found in advanced cancers. To evaluate the role of the PTEN/MMAC1 gene in leukemia, bone marrow and/or peripheral blood from 62 acute myeloid leukemia (AML) patients, 5 hemopoietic cell lines (HL60, U937, Raji, KG‐1, K562), and 30 normal controls were analyzed. The results showed aberrant PTEN/MMAC1 transcripts in 15 of the 62 (24%) AML patients, 4 of the 5 cell lines (80%), and 4 of the 30 (13%) normal controls. As in our previous study of TSG101, the abnormal transcripts may result from aberrant RNA splicing as evidenced by the presence of both these aberrant transcripts and normal full length transcripts in all specimens examined. Loss of heterozygosity (LOH) analysis and PCR‐SSCP of the entire coding region showed that none of the AML cases had LOH or mutation. Only one frameshift mutation at codon 130 (insertion of CCCG) with premature termination of coding sequence was observed in the U937 cell line. Our results indicate that the PTEN/MMAC1 gene may play a role in a small percentage of AML, but its significance needs to be further evaluated. Am. J. Hematol. 63:170–175, 2000.

Quality of life and its correlates in HIV/AIDS male outpatients receiving highly active antiretroviral therapy in Taiwan

Abstract  Long‐term care of human HIV and AIDS cases has raised quality of life (QoL) issues. The aim of this study was to identify QoL in HIV/AIDS male outpatients receiving highly active antiretroviral therapy (HAART) and its correlates in Taiwan. In total, 41 HIV/AIDS male outpatients receiving HAART yet presenting few symptoms of infection, were recruited for the study. Their QoL levels were measured with the Taiwan version of the Short Form of the World Health Organization Quality of Life questionnaire (WHOQOL‐BREF). The relationships between QoL and demographic characteristics, social support, negative stressors, depression, characteristics of HIV infection, attitude toward HIV infection, and adverse effects of HAART, were examined. The results of the analysis reveal that multiple factors affect QoL for HIV/AIDS male outpatients receiving HAART, including severity of depression, deterioration of work function, inconvenience resulting from medication schedules and medical appointments, lack of social support, negative stressors, and adverse effects of HAART. The results provide screening factors so that clinicians can intervene to improve the QoL for their HIV patients.

Methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii on computer interface surfaces of hospital wards and association with clinical isolates.

BackgroundComputer keyboards and mice are potential reservoirs of nosocomial pathogens, but routine disinfection for non-water-proof computer devices is a problem. With better hand hygiene compliance of health-care workers (HCWs), the impact of these potential sources of contamination on clinical infection needs to be clarified.MethodsThis study was conducted in a 1600-bed medical center of southern Taiwan with 47 wards and 282 computers. With education and monitoring program of hand hygiene for HCWs, the average compliance rate was 74% before our surveillance. We investigated the association of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Acinetobacter baumannii, three leading hospital-acquired pathogens, from ward computer keyboards, mice and from clinical isolates in non-outbreak period by pulsed field gel electrophoresis and antibiogram.ResultsOur results revealed a 17.4% (49/282) contamination rate of these computer devices by S. aureus, Acinetobacter spp. or Pseudomonas spp. The contamination rates of MRSA and A. baumannii in the ward computers were 1.1% and 4.3%, respectively. No P. aeruginosa was isolated. All isolates from computers and clinical specimens at the same ward showed different pulsotypes. However, A. baumannii isolates on two ward computers had the same pulsotype.ConclusionWith good hand hygiene compliance, we found relatively low contamination rates of MRSA, P. aeruginosa and A. baumannii on ward computer interface, and without further contribution to nosocomial infection. Our results suggested no necessity of routine culture surveillance in non-outbreak situation.

Dihydropyrimidine dehydrogenase pharmacogenetics in the Taiwanese population.

Background/purpose5-Fluorouracil (5-FU) remains the most frequently used chemotherapy agent in various human cancers. Over 80% of the 5-FU administered is metabolized by dihydropyrimidine dehydrogenase (DPD) in the liver. However, mutations in the DPD gene have been found to be associated with low DPD activity causing severe complications. The aim of this study was to determine the frequency of 11 known mutations in Taiwanese subjects and the relationship between mutation and DPD level.MethodsSamples from a total of 300 subjects were investigated in this study. The PCR-RFLP method was used to identify 11 mutations of the DPYD gene, including 62G>A, 74A>G, 85T>C (DPYD*9A), 812delT, 1003G>T, 1156G>T, 1627A>G (DPYD*5), 1714C>G, 1897delC (DPYD*3), 2194G>A (DPYD*6), and IVS14+1G>A (DPYD*2A). DPD protein levels were determined using a DPD ELISA kit.ResultsFour mutations, including 74A>G, 85T>C (DPYD*9A), 1627A>G (DPYD*5), and 2194G>A (DPYD*6), were found in our 300 samples. The following mutations were not detected: 62G>A, 812delT, 1003G>T, 1156G>T, 1714C>G, 1897delC (DPYD*3), and IVS14+1G>A (DPYD*2A). The phenotype analysis by DPD protein level indicated that the 1627A>G (DPYD*5) mutation was not associated with the DPD protein level and might be a polymorphism in the DPD gene. The DPD level was also not correlated with gender.ConclusionNo significant correlations between these 11 mutations and DPD protein level were found indicating that examination of these mutations is insufficient to provide a high-value prediction of the 5-FU pharmacogenetic syndrome in Taiwanese. Genotype and phenotype analysis indicated the 1627A>G (DPYD*5) mutation to be a polymorphism.

Dengue virus-associated hemophagocytic syndrome and dyserythropoiesis: a case report.

A 33‐year‐old man had dengue hemorrhagic fever with initial presentation of fever, leukocytosis, and thrombocytopenia. The cause of the subsequent rapid decline in red cell counts without evidence of intravascular hemolysis or massive bleeding was confirmed as hemophagocytosis and dyserythropoiesis by bone marrow study. The patient recovered with supportive care and the bone marrow pattern was normal on repeated bone marrow study. To our knowledge, this is the first reported case of dengue virus‐associated hemophagocytosis and dyserythropoiesis in Taiwan. Clinicians should consider that the occurrence of hemophagocytosis and dyserythropoiesis could be due to dengue virus infection. That this dengue virus infection was confirmed by a positive serology result at the convalescent stage but not at the acute symptomatic stage underlines the need for a second dengue serology study, as dengue infection can be missed due to an initial negative serology result.

Automated, continuous, and dynamic speciation of urinary arsenic in the bladder of living organisms using microdialysis sampling coupled on-line with high performance liquid chromatography and hydride generation atomic absorption spectrometry

An on-line and fully automated method was developed for the continuous and dynamic in vivo monitoring of four arsenic species [arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)] in urine of living organisms. In this method a microdialysis sampling technique was employed to couple on-line with high performance liquid chromatography (HPLC) and hydride generation atomic absorption spectrometry (HGAAS). Dialysates perfused through implanted microdialysis probes were collected with a sample loop of an on-line injector for direct and automated injection into HPLC system hyphenated with HGAAS. The saline (0.9% NaCl) solution was perfused at the rate of 1 microl min(-1) through the microdialysis probe and the dialysate was loaded into 50 microl of sample loop. The separation conditions were optimally selected to be in phosphate buffer solution at a pH 5.2 with a flow rate of 1.2 ml min(-1). The effluent from the HPLC was first mixed on-line at the exit of the column with HCl (1 M) solution and then mixed with a NaBH4 (0.2% m/v) solution. Based on the optimal conditions obtained, linear ranges of 2.5-50 ng ml(-1) for AsIII and 6.75-100 ng ml(-1) for the other three arsenic species were obtained. Detection limits of 1.00, 2.18, 1.03 and 2.17 ng ml(-1) were obtained for AsIII, DMA, MMA and AsV, respectively. Typical precision values of 3.4% (AsIII), 5.4% (DMA), 3.6% (MMA) and 7.5% (AsV) were obtained, respectively, at a 25 ng ml(-1) level. Recoveries close to 100%, relative to an aqueous standard, were observed for each species. The average in vivo recoveries of AsIII, DMA, MMA and AsV in rat bladder urine were 56+/-5%, 60+/-9%, 49+/-3% and 55+/-7%, respectively. The use of an on-line microdialysis-HPLC-HGAAS system permitted the determination of four urinary arsenic species in the bladder of an anesthetized rat with a temporal resolution of 50 min sampling.

Salmonella choleraesuis bacteremia in southern Taiwan.

Within a 6-year period from January 1991 to December 1996, 19 patients with Salmonella choleraesuis bacteremia were enrolled for clinical and microbiological analysis. Young children, the elderly and patients with hematological malignancy (36.8%), liver cirrhosis (26.3%), systemic lupus erythematosus (10.5%), chronic renal impairment (10.5%), and peptic ulcer (10.5%) were at high risk of this infection. The ratio of male to female was 3:1. Three cases (15.8%) were nosocomially acquired. Fever (89.5%), chills (57.9%) and anorexia (52.6%) were the most common clinical manifestations. Seven patients (36.8%) presented no gastrointestinal manifestations. Normal white blood cell count was noted in seven patients (36.8%), and neutropenia caused by underlying diseases or severe infection was found in six cases (31.6%). Various types of metastatic focal infections were found, such as septic arthritis, cutaneous infection, spontaneous bacterial peritonitis, and pneumonia. The severe immunocompromised status of patients and the high virulence of this pathogen may contribute to the high case fatality rate (21%). Higher resistance rate to commonly used antimicrobial agents was noted in ampicillin (94.7%), chloramphenicol (89.5%), and TMP/SMZ (63.8%). All strains of S. choleraesuis were susceptible to third-generation cephalosporins and fluoroquinolones. Generally, S. choleraesuis bacteremia should be taken into account in the differential diagnosis of sepsis in immunocompromised patients, even without gastrointestinal manifestations. The third-generation cephalosporins and fluoroquinolones may be the first choice for treatment of this invasive infections.

Hematological Aspects of Dengue Fever

Fifty patients with dengue fever from Sept. 1987 to Jan. 1988 were studied for hematological features. The lowest blood counts values throughout the course of illness were Hb: 13.2 +/- 1.9 gm/dl, WBC: (2.77 +/- 1.63) x 10(3)/mm3, Platelet: (8.7 +/- 5.5) x 10(4)/mm3. Leukopenia (WBC less than 4000/mm3) was present in 38 (76%) of the cases and thrombocytopenia (platelet less than 10 x 10(4)/mm3) in 27 (54%) of the cases. Leukocytes reached nadir (1000-2000/mm3) at the 5th-6th day after fever onset, thrombocytes reached nadir (2.0-5.0 x 10(4)/mm3) at the 5th-7th day after fever onset. Bone marrow studies showed mild hypocellularity in the acute stage (less than 1 week) and normal cellularity in the convalescent stage (greater than 1 week). Megakaryocytes increased with various stages of maturation of megakaryocytes appearing in a majority of patients. Nuclear vacuolization of megakaryocytes could also be found. Bone marrow CFU-GM when performed within one week of illness showed no growth or low colony count, and was nearly normal after one week of fever onset. This study may suggest that leukopenia in dengue fever may be caused by virus-induced destruction or inhibition of myeloid progenitor cells. Thrombocytopenia may result from by destruction of peripheral platelet or bone marrow megakaryocytes by viruses which consequently reduce the platelet production.