| Misun Park | 4 Articles |
Objectives
<i>Mycobacterium intracellulare</i> is the major causative agent of nontuberculous mycobacteria-related pulmonary infections. The strain typing of <i>M. intracellulare</i> is important for the treatment and control of its infections. We compared the discrimination capacity and effective value of four different molecular typing methods. Methods Antibiotic susceptibility testing, <i>hsp65</i> and <i>rpoB</i> sequencing, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), mycobacteria interspersed repetitive-unit-variable-number tandem-repeat analysis (MIRU-VNTR), and VNTR assay targeting 44 <i>M. intracellulare</i> isolates obtained from patients with pulmonary infections were performed. Results All the antibiotic susceptibility patterns had no association with the molecular and sequence types tested in this study; however, the molecular and sequence types were related with each other. PFGE gave best results for discriminatory capacity, followed by VNTR, MLST, and MIRU-VNTR. Conclusion The high discriminatory power of PFGE, VNTR, and MLST is enough for differentiating between reinfection and relapse, as well as for other molecular epidemiological usages. The MLST could be regarded as a representative classification method, because it showed the clearest relation with the sequence types. Citations
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Objectives
Our previous longitudinal multicenter-based carriage study showed that the average carriage rate of <i>Streptococcus pneumoniae</i> was 16.8% in 582 healthy children attending kindergarten or elementary school in Seoul, Korea. We assessed serotype-specific prevalence and antimicrobial resistance among colonizing pneumococcal isolates from young children in the era of low use of the seven-valent pneumococcal conjugate vaccine (PCV7). Methods Serotypes were determined by an agglutination test with specific antisera or by a multiplex polymerase chain reaction (PCR) assay. An antimicrobial susceptibility test was performed with broth microdilution in Korean 96-well panels from Dade-MicroScan (Sacramento, CA, USA). Results Pneumococcal colonization patterns were dynamic and longterm persistent carriage was rare, which indicated a sequential turnover of pneumococcal strains. Of the 369 pneumococci (except for 23 killed isolates), 129 (34.9%) isolates were PCV7 vaccine serotypes (VTs); 213 (57.8%) isolates were nonvaccine serotypes (NVTs); and the remaining 27 (7.2%) isolates were nontypable (NT). The highest rates of multidrug resistance (MDR) were observed in VTs (86.0%; 111/129 isolates) and NVTs (70.0%; 149/213 isolates). Conclusion This study overall showed the frequent carriage of VTs and NVTs with MDR in healthy children attending kindergarten or elementary school. Efforts should be directed toward reducing the extensive prescription of antibiotics and using new broader vaccines to reduce the expansion of MDR strains of NVTs in our community. Citations
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Objectives
A multiplex real-time polymerase chain reaction (RT-PCR) method was developed for the identification of three <i>Vibrio</i> species: <i>Vibrio cholerae</i>, <i>Vibrio parahaemolyticus</i>, and <i>Vibrio vulnificus</i>. Methods Specific primers and probes targeting the <i>hlyA</i>, <i>tlh</i>, and <i>vvhA</i> genes were selected and used for multiplex real-time PCR to confirm the identification of <i>V. cholerae</i>, <i>V. parahaemolyticus</i>, and <i>V. vulnificus</i>, respectively. This method was applied to screen <i>Vibrio</i> species from environmental samples and combining it with a culture-based method, its effectiveness was evaluated in comparison with culture-based methods alone. Results Specific PCR fragments were obtained from isolates belonging to the target species, indicating a high specificity of this multiplex real-time PCR. No cross-reactivity with the assay was observed between the tested bacteria. The sensitivity of the multiplex real-time PCR was found to have a lower limit of 10<sup>4</sup> colony-forming units/reaction for all three <i>Vibrio</i> species. The combination strategy raised the isolation ratio of all three <i>Vibrio</i> species 1.26- to 2.75-fold. Conclusion This assay provides a rapid, sensitive, and specific technique to detect these three <i>Vibrio</i> species in the environment. Citations
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Two real-time polymerase chain reaction assays were developed to detect mutations in codons 83 and 87 in <i>gyrA</i> and in codons 80 and 91 in <i>parC</i>, the main sites that causes quinolone resistance in pathogenic <i>Escherichia coli </i>and <i>Shigella</i> spp. isolates. These assays can be employed as a useful method for controlling infections caused by quinolone-resistant <i>E coli </i>and <i>Shigella</i> isolates.
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