Genetic Correlation of Community-Associated Methicillin-Resistant Staphylococcus aureus Strains from Carriers and from Patients with Clinical Infection in One Region of Korea

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an increasingly common worldwide and colonizing S. aureus strains may serve as the causative pathogen for overt clinical infections. This study was performed to determine whether the pathogenic CA-MRSA isolate in clinical infections was genetically related to the MRSA isolates in community carriers. We prospectively collected a total of 42 CA-MRSA isolates (23 clinical infection isolates and 19 colonization isolates) in a local region of Korea. Antimicrobial susceptibility tests, staphylococcal toxin assays, SCCmec typing, multilocus sequence typing (MLST), and spa (staphylococcal protein A) typing were performed with all isolates. Thirty-four (81%) of 42 CA-MRSA isolates belonged to sequence type (ST) 72 in the MLST analysis. The distribution of STs did not differ significantly between colonization and clinical infection isolates (89.5% [17/19] vs. 73.9% [17/23], P=0.26). Among the ST72-MRSA isolates, spa type t664 (18, 52.9%) and t324 (8, 23.5%) were common in both groups. This study demonstrates that the community-associated MRSA strains from patients with clinical infections are closely related to the strains found in carriers from one local community.

Detection of Fungus and Bacteria in Otitis Media with Effusion of Children Using Polymerase Chain Reaction and Its Correlation of Clinical Factors / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Several hypotheses have been proposed in the etiopathogenesis of otitis media with effusion (OME). The bacterial or fungal infection may also play a major role in the pathogenesis of OME. To investigate the relationship between bacteria and fungi as pathogens in OME and to analyze the incidence, the authors evaluated the pathogens of OME using polymerase chain reaction (PCR) technique, which is known to be more sensitive and specific than conventional bacterial and fungal culture. SUBJECTS AND METHOD: Twenty-three children (thirty ears), who were diagnosed with OME and had underwent ventilation tube insertion, were evaluated in the department of ORL-HNS, University Hospital, from May 2006 to March 2007. The middle ear effusion, obtained during the procedure, was evaluated for the identification of bacteria and fungi by PCR. RESULTS: Among 30 ears, viable pathogenic bacteria were detected in 20 ears (66.6%) and fungi in 13 ears (43.3%). The bacterial pathogens included Haemophilus influenzae (13 ears), followed by Streptococcus pneumonize (6 ears). The fungi detected from PCR were Candida albicans (4 ears-30.8%), Aspergillus niger (2 ears-15.4%) and Paecilomyces lilacinus (2 ears-15.4%). Additional pathogens include Basidiomycete yeast, Saccharamycete sp., Eurotium rubrum, Dothioraceae sp. and Stemphylium solani. Detection of fungal DNA was more common in patients with cleft palate and in recurrent cases with statistical significance. CONCLUSION: The use of PCR of middle ear effusion is effective for the detection of pathogens in patients with OME. While bacteria were thought to be the causative pathogen, this study suggests the etiological role of fungi in the pathogenesis of OME. However, the relationship between fungi and OME requires further studies.

The Proportion of Rifabutin-susceptible Strains among Rifampicin- resistant Isolates and Its Specific rpoB Mutations / 결핵및호흡기질환

BACKGROUND: Rifabutin (ansamycin) is a spiro-piperidyl rifamycin, which is highly active against Mycobacterium tuberculosis. It has been found that some clinical isolates of tubercle bacilli that are resistant to rifampicin are susceptible to rifabutin, with some patients with multi-drug resistant pulmonary tuberculosis having shown favorable clinical and bacteriological responses to the rifabutin. This study was conducted to find the proportion of rifabutin- susceptible strains among rifampicin-resistant isolates from Korean MDR-TB patients, and investigate the presence of specific rpoB mutations, which may confer resistance to rifampicin, but not to rifabutin. METHODS: 201 rifampicin-resistant and 50 pan-susceptible M. tuberculosis isolates were randomly selected for this study. The isolates were retested at rifampicin and rifabutin concentrations of 0, 20, 40 and 80 microgram/ml, respectively. The isolates that grew at and/or over a rifabutin concentration of 20 microgram/ml were judged rifabutin-resistant. The rpoB gene was extracted from the isolates, and then amplified for direct sequencing to investigate specific rpoB mutations that conferred rifabutin- susceptibility but rifampicin-resistance. RESULTS: Out of the 201 rifampicin-resistant M. tuberculosis, 41 strains (20.4%) were susceptible to rifabutin using the absolute concentration method on Lowenstein-Jensen media. The rpoB mutation types that showed susceptibility to rifabutin were Leu511Pro, Ser512Arg, Gln513Glu, Asp516Ala, Asp516Gly, Asp516Val, Asp516Tyr, Ser522Leu, His526Asn, His526Leu, His526Cys, Arg529Pro and Leu533Pro. A reverse hybridization technique was able to detect 92.5% of the rifabutin-susceptible isolates, with a specificity of 96.1% among 195 M. tuberculosis isolates with the rpoB mutation. CONCLUSIONS: Around 20% of the rifampicin-resistant isolates in Korea showed susceptibility to rifabutin, which was associated with some specific mutations of rpoB. Rifabutin could be used for the treatment of MDR-TB patients, especially when drug susceptibility testing reveals susceptibility to rifabutin.

Epidemiologic Trends of Rotavirus Infection in the Republic of Korea, July 1999 through June 2002 / 대한진단검사의학회지

BACKGROUND: Rotavirus is the most common cause of childhood diarrhea worldwide. Although rotavirus is also the leading cause of infant and childhood diarrhea in Korea, much remains unknown about the trends of rotavirus infection by month and geographic region in Korea. To monitor epidemiologic trends of rotavirus infection, a laboratory-based rotavirus surveillance network was established in 2002. This is the first nationwide, multicenter evaluation of rotavirus epidemiology in Korea. METHODS: The rotavirus test results were collected retrospectively from eight network laboratories, from July 1999 to June 2002. Four laboratories used latex agglutination, three used immunochromatography, and one used enzyme-linked fluorescent assay for the detection of rotavirus antigen. RESULTS: Of 10, 441 stool specimens, 2, 496 (23.9%) were positive for rotavirus. During the 3-year period, the rotavirus season began in December-January, and ended in April-May. The rotaviruspositive percentage of summer, autumn, winter, and spring was 11.5%, 10.0%, 32.8%, and 30.0%, respectively. A few hospitals revealed summer epidemics. The rotavirus positive rate in each hospital varied from 15.3% to 44.2%. A common feature of the three hospitals showing the lowest rotavirus-positive percentage (i.e. 800 beds). The secondary care hospitals showed a higher positive proportion (27.5%) compared with tertiary care hospitals (21.1%). CONCLUSIONS: Overall, the rotavirus-positive percentage among all diarrheal specimens was similar to that of other developed countries. The results of this study showed that the autumn epidemic of the rotavirus has declined or disappeared and the peak season for rotavirus has shifted to late winter/early spring in Korea.

Antimicrobial Susceptibilites of Glycopeptides, Arbekacin and Quinupristin/Dalfopristin against Staphylococcal aureus isolates / 감염

No abstract available.

Detection of rpoB Gene Mutation in Rifampin-Resistant M. Tuberculosis by Oligonucleotide Chip / 결핵

BACKGROUND: Oligonucleotide chip technology has proven to be a very useful tool in the rapid diagnosis of infectious disease. Rifampin resistance is considered as a useful marker of multidrug-resistance in tuberculosis. Mutations in the rpoB gene coding β subunit of RNA polymerase represent the main mechanism of rifampin resistance. The purpose of this study was to develop a diagnosis kit using oligonucleotide chip for the rapid and accurate detection of rifampin-resistance in Mycobacterium tuberculosis. METHOD: Tle sequence specific probes for mutations in the rpoB gene were designed and spotted onto the glass slide, oligonucleotide chip. 38 clinical isolates of Mycobacterium were tested. A part of rpoB was amplified, labelled, and hybridized on the oligonucleotide chip with probes. Results were analyzed with a laser scanner. Direct sequencing was done to verify the results. RESULT: The low-density oligonucleotide chip designed to determine the specific mutations in the rpoB gene of M. tuberculosis accurately detected rifampin resistance associated with mutations in 28 clinical isolates. Mutations at codons 531, 526, and 513 were confirmed by direct sequencing analysis. CONCLUSION: Mutant detection using oligonucleotide chip technology is a reliable and useful diagnostic tool for the detection of multidrug-resistance in M. tuberculosis.