Young Sook Kim

Frequency of Extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase Genes in Escherichia coli and Klebsiella pneumoniae over a Three-year Period in a University Hospital in Korea

BACKGROUND The aim of this study was to determine the yearly prevalence and genotype distribution of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae collected over a 3-yr period in Gwangju, Korea. METHODS Clinical isolates of E. coli and K. pneumoniae collected at Chosun University Hospital from September 15, 2005 to September 14, 2008 were evaluated. Antimicrobial susceptibility testing was performed using the Vitek II system (bioMérieux, USA) and agar dilution methods. Screening for ESBL and AmpC β-lactamase genes was performed using PCR amplification of plasmid DNA followed by direct sequencing of the PCR products. RESULTS The percentage of ESBL-producing isolates was 12.6% (196/1,550) for E. coli and 26.2% (294/1,121) for K. pneumoniae. The ESBL gene sequencing results showed that the most prevalent ESBL types were CTX-M (93.5%) and SHV (12.9%) in E. coli, and SHV (73.2%) and CTX-M (46.3%) in K. pneumoniae. The most common ESBL in E. coli was CTX-M-15-like, followed by CTX-M-14-like, SHV-2a-like, and SHV-12-like. The most prevalent ESBL type in K. pneumoniae was SHV-12, followed by CTX-M-14-like and CTX-M-15-like. Fifty-one percent (21/41) of ESBL-producing K. pneumoniae with ESBL types verified by sequencing also had DHA-1-like AmpC β-lactamases. However, none of the ESBL-producing E. coli was positive in the AmpC β-lactamase PCR analysis. CONCLUSIONS In this study, the most common types of class A ESBLs identified were CTX-M-15-like in E. coli and SHV-12-like in K. pneumoniae.

Comparison of the Vitek 2, API 20A, and 16s rRNA Gene Sequencing for the Identification of Anaerobic Bacteria

Comparison of the Vitek 2, API 20A, and 16s rRNA Gene Sequencing for the Identification of Anaerobic Bacteria Gyun Cheol Park, Sook Jin Jang, Min Jung Lee, Joong-Ki Kook, Min Jung Kim, Young Sook Kim, Nam Woong Yang, Hye Soo Lee, Seong Ho Kang, Geon Park, Dae Soo Moon Department of Laboratory Medicine, Research Center for Resistant Cells, Chosun University College of Medicine, Department of Oral Biochemistry, College of Dentistry, Chosun University, Departments of Radiology, Chosun University College of Medicine, Department of Microbiology, College of Medicine, Chosun University, Gwangju, Department of Laboratory Medicine, Chonbuk National University Medical School, Chonbuk National University Hospital Branch of National Culture Collection of Pathogens, Jeonju, Korea

Basic Concepts of Bacterial Taxonomy

The three components of taxonomy are classification, nomenclature and identification. Traditionally, bacterial classification and identification were performed based on the morphology and the biochemical data of the bacteria. In newer theories, or so-called natural concepts, the relationships between bacteria are based on the overall similarities of both the phenotypic and genotypic characteristics. The polyphasic taxonomy, or current taxonomy, describes the integration of all of the available genotypic, phenotypic, and phylogenetic information into a consensus type of general-purpose classification. When routine identification methods that are based on the biochemical tests fail, alternative procedures such as complete 16s rRNA gene sequence analysis are required. Although the results of 16s rRNA gene sequence analysis have not been fully discriminatory to differentiate closely related species, they may guide the additional analyses that are required for species identification. (Korean J Clin Microbiol 2012;15:79-87)

A Strain of Nocardia cyriacigeorgica Isolated from a Patient with Pulmonary Infection

Nocardia cyriacigeorgica is an aerobic gram-positive rod that has mostly been reported as an opportunistic pathogen. Since molecular methodologies were introduced to identify species, infections caused by N. cyriacigeorgica have been reported. The patient was a 51-year-old woman with aplastic anemia, systemic lupus erythematosus, and disseminated tuberculosis, who was admitted to Chosun University Hospital with a history of fever and productive cough. During her hospitalization, sputum cultures were taken and a bacterium suspicious of acitinomycetes grew five times. It was a gram-positive rod that was also partially acid-fast on modified Kinyoun stain and resistant to lysozyme. After 24 h of incubation, cultures of the sputum onto sheep’s blood agar plates (BAP) demonstrated rough, chalky, and white colonies with a characteristic earthy odor. Based on the above results, the presumptive identification of Nocardia species was made. To identify species of this isolate, 16S rRNA gene sequence analysis was taken and showed 99.9% homology to N. cyriacigeorgica DSM44484. The results of biochemical tests were compatible with other reports of N. cyriacigeorgica. As a result, this isolate was identified as N. cyriacigeorgica. Herein, we present a first report of N. cyriacigeorgica isolated from a patient with pulmonary infection in Korea. (Korean J Clin Microbiol 2008;11:136-140)