• Journal of Microbiology and Biotechnology
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• 제31권9호
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• pp.1288-1294
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• 2021

There are a growing number of reports of hospital-acquired infections caused by pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). Many plant products are now being used as a natural means of exploring antimicrobial agents against different types of human pathogenic bacteria. In this research, we sought to isolate and identify an active molecule from Sedum takesimense that has possible antibacterial activity against various clinical isolates of MRSA. NMR analysis revealed that the structure of the HPLC-purified compound was 1,2,4,6-tetra-O-galloyl-glucose. The minimum inhibitory concentration (MIC) of different extract fractions against numerous pathogenic bacteria was determined, and the actively purified compound has potent antibacterial activity against multidrug-resistant pathogenic bacteria, i.e., MRSA and its clinical isolates. In addition, the combination of the active compound and β-lactam antibiotics (e.g., oxacillin) demonstrated synergistic action against MRSA, with a fractional inhibitory concentration (FIC) index of 0.281. The current research revealed an alternative approach to combating pathogenesis caused by multi-drug resistant bacteria using plant materials. Furthermore, using a combination approach in which the active plant-derived compound is combined with antibiotics has proved to be a successful way of destroying pathogens synergistically.

• Korean Journal of Clinical Laboratory Science
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• 제41권4호
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• pp.153-157
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• 2009

The production of extended-spectrum ${\beta}$-lactamases ($ESBL_S$) of the TEM or SHV type by bacterial pathogens is a major threat to the use of the clinically important expanded-spectrum cephalosporins. The characterization of the SHV ESBLs producing Klebsiella pneumoniae strains present in clinical isolates is time-consuming processes. We describe here in the development of a novel system, which consists of a real time PCR. We found 11 K. pneumoniae strains to be presumptive strains ESBLs producers by clinical and laboratory standards institute (CLSI) guidelines. The double disk synergy test showed 8 ESBL positive and conventional PCR showed 10 SHV ESBL positive, which were K. pneumoniae strains isolates. By real time PCR analysis, SHV gene in 11 of 11 strains were identified. When sequencing analysis was compared with real time PCR, both analysis were presented 99% similarity. In this study, we used a rapid, sensitive, and specific real-time PCR (RT-PCR) method for detection of the assay SHV ESBL producing K. pneumoniae strains in clinical isolates.

• Tuberculosis and Respiratory Diseases
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• 제64권6호
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• pp.422-426
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• 2008

Background: Mycobacterium abscessus is the most pathogenic and drug-resistant rapid-growing mycobacterium. Clarithromycin or azithromycin are the only regular oral antimycobacterial agents that have an effect on M. abscessus. We tried to detect the clarithromycin-resistant strains from the clinical isolates of M. abscessus. Methods: We tried to isolate the clarithromycin-resistant strains from 220 clinical isolates of M. abscessus by performing using reverse hybridization assay (RHA) and the broth microdilution test (BMT). Results: Seven resistant strains (3.2%) from all the tested clinical isolates were detected by BMT. Three of these resistant strains were also detected by RHA and it was confirmed that they had point mutants. Conclusion: These results showed that clarithromycin resistance in M. abscessus clinical isolates is related to a point mutation and other unknown mechanisms.

• YAKHAK HOEJI
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• 제39권3호
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• pp.276-282
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• 1995

Compared to the first and second-generation cephalosporins, the third-generation cephalosporins are remarkably stable against hydrolysis by the $\beta$-lactamases produced by aerobic gram-negative bacilli, such as Enterobacteriaceae. Among these bacteria, the most prevalent plasmid-encoded $\beta$-lactamase is TEM-1 $\beta$-lactamase belonging to class A or group 2b. This enzyme is produced constitutively and is principally active against peniciflins and old cephalosporins rather than third-generafion cephalosporins, carbapenems and mmobactams. However, new TEM type $\beta$-lactamases including TEM-9 and TEM-12 evolved through point mutations in a gene encoding $\beta$-lactamase have been discovered from patients during chemotherapy. These $\beta$-lactamases are known to be capable of hydrolyzing most of the third-generatim cephalosporins. To study the prevalence of $\beta$-lactamases from clinical isolates collected in Korea. the minimal inhibitory concentratims(MICs) of several third-generation cephalosporins against 628 clinical isolates were determined by agar dilution methods, and $\beta$-lactamas-producing bacteria were isolated by use of cefinase disc. By polymerase chain reaction (PCR) method, clinical isolates harboring a gene for TEM type $\beta$-lactamase were identified among the $\beta$-lactamase producing strains. Twentiy three percent of the clinical isolates was resistant to the thirdgeneration cephalosporins, and more than 90% of resistant cells produced various $\beta$-lactamases. TFM type $\beta$-lactamases were dominant in gram-negative bacilli, such as Escherichia coli, Klebsiella pneumoniae, Enterobacter species. These results suggest the necessity of the development of new cephalosporins which are stable against $\beta$-lactamases like TEM.

• Journal of Microbiology
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• 제45권4호
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• pp.286-290
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• 2007

The purpose of this study was to investigate the prevalence and genetic mechanisms of erythromycin resistance in staphylococci. A total of 102 erythromycin resistant non-duplicate clinical isolates of staphylococci [78. coagulase negative stapylococci (CNS), 24 Staphylococcus aureus] were collected between October 2003 and August 2004 in Istanbul Faculty of Medicine in Turkey. The majority of the isolates were from blood and urine specimens. Antimicrobial susceptibilities were determined by the agar dilution procedure and the resistance phenotypes by the double disk induction test. A multiplex PCR was performed, using primers specific for erm(A), erm(B), erm(C), and msrA genes.. Among the 78 CNS isolates, 57.8% expressed the $MLS_{B}-constitutive$, 20.6% the $MLS_{B}-inducible$, and 21.6% the $MS_B$ phenotypes. By PCR, 78.2% of these isolates harbored the erm(C) gene, 8.9% erm(A), 6.4% erm(B), and 11.5% msrA genes. In S. aureus, the constitutive $MLS_B$ (58.3 %) was more common than the inducible phenotype (20.8%). erm(A) was detected in 50% and erm(C) in 62.5% of the isolates, while 37.5% contained both erm(A) and erm(C). erm(C)-associated macrolide resistance was the most prevalent in CNS, while ermC) and erm(A, C) was the most prevalent in S. aureus.

• Biomedical Science Letters
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• 제19권3호
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• pp.275-279
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• 2013

Etiological agents of extended spectrum ${\beta}$-lactamase (ESBL) producing uropathogenic Escherichia coli (UPEC) have become a major problem in urinary tract infections. The purpose of this study was to compare the molecular characteristics of ESBL producing UPEC strains isolated from 1989 and 2010. A total of 301 strains of UPEC clinical isolates was collected from Korean healthcare facility in 1989 (126 strains) and in 2010 (175 strains). UPEC clinical isolates were analyzed by multiplex polymerase chain reaction method (ESBL related bla genes and phylogenetic groups) and amplified fragment length polymorphism (AFLP). Among 301 isolates, ESBL producing UPEC were 8 strains (6.3%) in 1989 isolates and 35 strains (20%) in 2010 isolates. The rate of bla genes in ESBL producing UPEC from 1989 isolates and 2010 isolates were $bla_{TEM}$ (75% and 85.7%), $bla_{CTX-M}$ (0% and 91.4%), $bla_{OXA}$ (25% and 20%), $bla_{PER}$ (0% and 2.9%). The distribution of phylogenetic groups in 1989 isolates and 2010 isolates were A (37.5% and 11.4%), B2 (12.5% and 51.4%), and D (50% and 37.1%). The most prevalent ESBL related bla gene and phylogenetic group were $bla_{CTX-M}$ (91.4%) and B2 (51.4%) in 2010 isolates, while $bla_{CTX-M}$ was not detected in 1989 isolates. Among 43 ESBL producing UPEC were grouped into 12 clusters up to 76% of genetic similarities by AFLP analysis. During past twenty one years, the rate of the ESBL producing UPEC strains in 2010 isolates was increased than that of in 1989 isolates. Also, the most prevalent ESBL related bla gene has been changed from $bla_{TEM}$ to $bla_{CTX-M}$.

• Journal of Microbiology
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• 제40권2호
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• pp.166-169
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• 2002

Twenty strains of Cryptococcus neoformams isolated from environmental and clinical sources in Korea were examined for their serotypes. Two environmental isolates from pigeon excreta belonged to C. neoformans var. neoformans serotypes A. Of the 18 isolates from clinical specimens, 17 belonged to C. neoformans vats, neoiomans (serotype A : 16, serotype D : 1) and one belonged to C. neoformans vats, gattii serotype B, which was culturally unusual, producing mucous colonies. This is the first report of the identification of C. neoformans roar, gattii serotype B from a patient in Korea.

• Biomedical Science Letters
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• 제10권2호
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• pp.163-169
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• 2004

Worldwide, tuberculosis remains one of the leading infectious diseases, accounting for nearly 3 million deaths and more than 8 million new cases annually. DNA typing of Mycobacterium tuberculosis is important for the control of tuberculosis, since it can be used to track transmission route of tuberculosis, source of internal laboratory contaminations, and to answer questions on the nature of tuberculosis infections such as reactivation or exogenous reinfection of disease. At present, IS6110-based RFLP is the choice of method for typing large numbers of clinical isolates of M. tuberculosis, since it has the highest resolution power. However, RFLP requires long time, high cost and qualified experts, so only reference level laboratories can use the RFLP technique. In order to have an optional molecular typing method suitable for the clinical settings, this study evaluated the use of one of PCR-based typing methods, IS6110-based outward PCR for typing clinical isolates of M. tuberculosis. In brief, the results from this study showed that IS6110-based RFLP is useful to discriminate diverse clinical isolates of M. tuberculosis as well as to identify clinical isolates that belong to the same family or cluster groups that have been previously classified by RFLP analysis. In addition, the banding profiles resulted from IS6110-based outward PCR seemed to represent genomic characteristics of M. tuberculosis, since strains belong to the K-family generated unique band that is not present in any other strains but present only in the genome of K-family strains. The IS6110-based outward PCR was also shown to be useful with DNAs isolated directly from liquid cultures indicating this method can be suitable for typing M. tuberculosis in clinical settings.

• Korean Journal of Clinical Laboratory Science
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• 제42권2호
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• pp.71-80
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• 2010

Pseudomonas aeruginosa are important nosocomial pathogens. Their resistance to carbapenem is increasing and causing concerns in Korea. An increasing prevalence of carbapenem resistance mediated by acquired carbapenemase is being reported. Over a 10 month-period from July 2007 to April 2008, 32 strains of imipenem-nonsusceptible P. auruginosa were isolated from Kangwon National University Hospital. To determine the prevalence and genotypes of the carbapenemase-producing clinical isolates, the antibiotic susceptibility was determined by Microscan Walkaway 96 SI System and the carbapenem activity was detected by the modified Hodge test and the imipenem-EDTA-SMA double-disk synergy test. The metallo-${\beta}$-lactamase gene and OXA-type ${\beta}$-lactamase gene reported in Korea were detected by PCR. As for the result of PCR, 30 isolates of P. aeruginosa were found to have $bla_{IMP-1}$-like and 1 isolate was found to have $bla_{IMP-1}$-like and $bla_{IMP-2}$. No clinical isolates were found to have $bla_{SIM-1}$, $bla_{OXA-23}$-like and $bla_{OXA-24}$-like. Random amplified polymorphic DNA (RAPD)-PCR and dendrogram for genetical similarity to band patterns of each clinical isolates were examined. P. aeruginosa were grouped into 7 clusters of up to 50% of similarity index. In the P. aeruginosa group, PS3 was resistant to the most antibiotics, PS1 was susceptible to the most antibiotics. PS7 was resistant to aztreonam unlike other groups. This is the first report of prevalence of carbapenemase in Chuncheon.

• Biomedical Science Letters
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• 제27권4호
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• pp.264-269
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• 2021

The purpose of this study was to evaluate the disinfecting efficacy of peracetic acid (PAA), sodium hypochlorite (NaOCl) and phenol, which are representative disinfectants in medical environments using four types of multi-drug resistance (MDR) clinical isolates with healthcare-associated infections (HAI). 26 antibiotic susceptibility tests were conducted for the four types of MDR clinical isolates in the same way as for clinical specimens. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the disinfectants were determined by using in vitro liquid medium dilution method and inoculation of the plate medium. Both the MIC and MBC of phenol against MRSA and VRE were 3.1%, while those against KPC and MRPA were 6.2%. The MIC and MBC of peracetic acid (PAA) against MRSA, VRE, KPC, and MRPA were 0.18%. The MIC and MBC of sodium hypochlorite (NaOCl) against MRSA were 0.39% and 0.78%, respectively. Both values of MIC and MBC were 0.78% for VRE. In addition, KPC and MRPA showed 0.39% for MIC and 0.78% for MBC. For all MDR strains used in this study, sodium hypochlorite and peracetic acid showed significant sterilizing efficiency, while no clear correlation was identified between antibiotic resistance clinical isolated and ability of disinfection.