• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.50-55
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• 2001

Different polluted water samples were collected from a wastewater treatment plant, agricultural drainage canals, the River Nile, and irrigation canals. The samples were examined for the enumeration of Pseudomonas aeruginosa in the Sohag area, Egypt over a period of one year. A total of 240 isolates were collected and tested for their resistance to 12 common antibiotics and 6 heavy metals. The isolates were found to be less resistant to norfloxacin(1.7%), ofloxacin(4.6%), amikacin(9.6%), tobramycin (10.4), carbenicillin (15.4), and gentamycin (41.3%), yet more sensitive to rifampicin (75%), kanamycin (89.6%), ampicillin (90.8%), chloramphenicol (91.7%), streptomycin (92.9%), and tetracyclin(96.3%). In contrast, 7.1%, 12.9%, 25.4%, and 53.7% of the isolates were resistant to lead, cadmium, mercury, and zinc, respectively. None of the isolates had developed a resistance to silver or molybdenum. The high frequency of metal-antibiotic double resistance existed between lead and amikacin (56.5%), cadmium and ofloxacin (72.7%), zinc and norfloxacin (100%), and mercury and carbenicillin (94.6%). The high occurrence of antibiotic-resistant bacteria in natural water could be related to the widespread use of antibiotics, with possible public health hazard.

• 한국축산식품학회지
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• 제38권2호
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• pp.391-402
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• 2018

The aim of the present work was to provide information about Enterococcus strains isolated from pre-packaged chicken samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. We report the first study on the occurrence of antibiotic resistant enterococci in pre-packaged chicken samples in Ankara. A total of 97 suspicious enterococcal isolates were identified from 122 chicken samples. All isolates were identified to species level by phenotypic and molecular methods. In the 16S rDNA sequence analysis, Enterococcus faecium (61.85%) and Enterococcus faecalis (38.15%) were found to be the most frequently detected Enterococcus spp. Of the 97 isolates tested for hemolytic activity, 12.37% enterococcal strains were ${\beta}$-hemolytic. ${\beta}$-Hemolysin was most prevalent among E. faecium (58.33%) compared to E. faecalis (41.66%). Disk diffusion method was used for determining of antibiotic resistance. The analysis of the antimicrobial resistance of the 97 Enterococcus isolates revealed that the resistance to kanamycin (98.96%), rifampicin (80.41%) and ampicillin (60.82%) was most frequent. Furthermore, resistance to erythromycin (38.14%) and ciprofloxacin (34.02%) was also observed. The frequencies of resistance to tetracycline (9.27%), penicillin G (8.24%), and chloramphenicol (3.09%), gentamicin (2.06%) and streptomycin (1.03%) were low. None of the isolates was resistant to vancomycin. Multi-drug resistance was found in 97.93% of Enterococcus strains. E. faecium strains showed a more resistant phenotype than E. faecalis strains according to the antibiotic resistance levels. The results of this study indicated that chicken meat is a potential reservoir for the transmission of antibiotic resistance from animals to humans.

• Journal of Animal Science and Technology
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• 제65권1호
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• pp.175-182
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• 2023

Antibiotics have been used in livestock production for not only treatment but also for increasing the effectiveness of animal feed, aiding animal growth, and preventing infectious diseases at the time when immunity is lowered due to stress. South Korea and the EU are among the countries that have prohibited the use of antibiotics for growth promotion in order to prevent indiscriminate use of antibiotics, as previous studies have shown that it may lead to increase in cases of antibiotic-resistant bacteria. Therefore, this study evaluated the number of antibiotic resistance genes in piglets staging from pre-weaning to weaning. Fecal samples were collected from 8 piglets just prior to weaning (21 d of age) and again one week after weaning (28 d of age). Total DNA was extracted from the 200 mg of feces collected from the 8 piglets. Whole metagenome shotgun sequencing was carried out using the Illumina Hi-Seq 2000 platform and raw sequence data were imported to Metagenomics Rapid Annotation using Subsystem Technology (MG-RAST) pipeline for microbial functional analysis. The results of this study did not show an increase in antibiotic-resistant bacteria although confirmed an increase in antibiotic-resistant genes as the consequence of changes in diet and environment during the experiment.

• Journal of Microbiology and Biotechnology
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• 제29권9호
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• pp.1460-1469
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• 2019

The extensive distribution of multidrug-resistant (MDR) methicillin-resistant Staphylococcus aureus (MRSA) poses a threat to healthcare worldwide. This study aimed to investigate the MDR and molecular patterns of MRSA isolates in children admitted to the two biggest tertiary care pediatric hospitals in northern and southern Vietnam. A total of 168 MRSA strains were collected to determine antibiotic susceptibility by minimum inhibitory concentration tests. Antibiotic-resistant genes, pulsed-field gel electrophoresis, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing were used for the molecular characterization of MRSA. Among the total strains, the MDR rate (51.8%) was significantly higher in the northern hospital than in the southern hospital (73% vs. 39%, p < 0.0001). The MDR-MRSA with the highest rates were "ciprofloxacin-erythromycin-gentamicintetracyclines" (35.6%), followed by "erythromycin-tetracycline-chloramphenicol" (24.1%), and "ciprofloxacin-erythromycin-gentamicin" (19.5%), showing an accumulative total of 79.3%. The most susceptible antibiotics were rifampicin (100%) and vancomycin (100%), followed by doxycycline (94.0%), meropenem (78.0%), and cefotaxime (75.0%). The SCCmecII strains showed greater resistance to gentamicin, ciprofloxacin, tetracycline, meropenem and cephalosporins compared with the other strains. The SCCmecII strains exhibited the highest rate in the tested genes (aacA/aphD: 55.2%, ermA/B/C: 89.7%, and tetK/M: 82.8%). ST5-SCCmecII was the predominant clone in the northern hospital, whereas SCCmecIVa was more pronounced in the southern hospital. In conclusion, our results raised concerns about the predominant MDR-MRSA strains in the pediatric hospitals in Vietnam. The north-south difference in the antibiotic resistance patterns and genetic structure of MRSA suggests different MRSA origins and various uses of antimicrobial agents between the two regions.

• 약학회지
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• 제48권1호
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• pp.27-29
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• 2004

The essential oil fractions from six plant parts including leaf of Zanthoxylum piperitum and flower of Lindera obtusiloba have revealed to possess resistance inhibitory activity on antibiotic resistant Staphylococcus aureus SA2 when combined with ohloramphenicol (Cm). The combination of Cm and essential oil mixtures showed potent resistance inhibition in the level of 10∼20 $\mu\textrm{g}$/ml.

• 약학회지
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• 제24권1호
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• pp.1-10
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• 1980

Viomycin inhibited polypeptide biosynthesis, initiation complex formation and translocation of peptidyl-tRNA on ribosomes derived from a sensitive strain of Mycobacterium smegmatis (R-15), but not significantly on ribosomes from viomycin-resistant mutants(R-31 and R-43). The inhibition of translocation was stronger than that of initiation complex formation in the sensitive strain. The binding of [$^{14}C$] tuberactinomycin O, a viomycin analog, to ribosomal particles was studied by Millipore filter method. The sensitive ribosome exhibited higher affinity for the antibiotic than the resistant ribosomes. The resistance was localized on the large ribosomal subunit in a mutant(R-31), and on the small subunit in another mutant(R-43). The binding of the drug to the sensitive ribosomal subunit was markedly reduced by combination with the resistant pair subunit, and the entire ribosome became resistant to the antibiotic.

• 한국어병학회지
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• 제25권2호
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• pp.77-84
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• 2012

Various antibiotics, that could induce the appearance of resistant microorganisms, have been used for treatment or prevention of bacterial diseases in marine and ornamental fish. We determined and characterized the level of antibiotic-resistant bacteria and proportion of multi-drug resistant bacteria in intestinal microflora of both marine fish cultured in Korea and imported ornamental freshwater fish. For this the bacterial species and resistance to antibiotics were investigated in intestine of rock bream Oplegnathus fasciatus cultured in Korea and pearl gourami Trichogaster leeri imported from Singapore to characterise. Although the bacterial species were different, proportions of resistant bacteria to single antibiotics or multi-drug were higher in intestinal microflora of pearl gourami Trichogaster leeri imported from Singapore than in rock bream Oplegnathus fasciatus cultured in Korea. These results indicate that various antibiotics have been being used before trading without measures in the market of asian ornamental fishes, providing high risks for the emergence of multi-drug resistant bacteria.

• Natural Product Sciences
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• 제13권4호
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• pp.342-346
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• 2007

The antimicrobial activity of the essential oil from Pelargonium graveolens and its effects when it was combined with current antibiotics against antibiotic-resistant strains of Streptococcus pneumoniae were evaluated. The minimal inhibitory concentrations (MICs) of the essential oil fraction and the main components of this plant were determined for two antibiotic-susceptible and two antibiotic-resistant strains of S. pneumoniae using broth microdilution tests. The combined effects of the oil with erythromycin, norfloxacin, or oxacillin were evaluated using a checkerboard microtitre assay. The combination of the oil fraction of P. graveolens, or its main component, together with the antibiotics tested significantly lowered the MICs of the antibiotics against all of the tested strains with fraction inhibiting concentration indices (FICs) ranging from 0.16 to 1.50. In particular, the activity of norfloxacin against all of the tested strains of S. pneumoniae was enhanced significantly by combination with citronellol. In conclusion, the combination of P. graveolens oil with antibiotics could be used to reduce the effective dose of antibiotic and to modulate the resistance of S. pneumoniae strains.

• Journal of Microbiology and Biotechnology
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• 제33권3호
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• pp.277-287
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• 2023

Since the first discovery of antibiotics, introduction of new antibiotics has been coupled with the occurrence of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Rapid dissemination of ARB and ARGs in the aquatic environments has become a global concern. ARB and ARGs have been already disseminated in the aquatic environments via various routes. Main hosts of most of ARGs were found to belong to Gammaproteobacteria class, including clinically important potential pathogens. Transmission of ARGs also occurs by horizontal gene transfer (HGT) mechanisms between bacterial strains in the aquatic environments, resulting in ubiquity of ARGs. Thus, a few of ARGs and MGEs (e.g., strA, sul1, int1) have been suggested as indicators for global comparability of contamination level in the aquatic environments. With ARB and ARGs contamination, the occurrence of critical pathogens has been globally issued due to their widespread in the aquatic environments. Thus, active surveillance systems have been launched worldwide. In this review, we described advancement of methodologies for ARGs detection, and occurrence of ARB and ARGs and their dissemination in the aquatic environments. Even though numerous studies have been conducted for ARB and ARGs, there is still no clear strategy to tackle antibiotic resistance (AR) in the aquatic environments. At least, for consistent surveillance, a strict framework should be established for further research in the aquatic environments.

• 대한수의학회지
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• 제45권2호
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• pp.163-168
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• 2005

This study was carried out to investigate the antibiotic resistance pattern of Enterococcus spp. and Staphylococcus aureus (S. aureus) isolated from chicken feces. All isolates showed high resistance to erythromycin (E) and tetracycline (TE). Of the 63 Enterococcus faecalis (E. faecalis) isolates, 73.0% were resistant to E and 98.4% to TE. Of the 44 Enterococcus faecium (E. faecium) isolates, 50.0% were resistant to E and 95.5% to TE. Of the 52 S. aureus isolates, 57.6% were resistant to E and 96.2% to TE. The prevalence of two and three drugs resistance pattern were 28.6% and 17.5% of E. faecalis, 40.9% and 25.0% of E. faecium and 38.5% and 23.1% of S. aureus, respectively. The multiple resistance pattern to six drugs was observed in 1 E. faecalis isolates, and five drugs resistance pattern were seen in 1 E. faecalis, 1 E. faecium and 1 S. aureus isolates. The prevalence of resistant organisms in Korea probably reflects lack of proper antibiotic policy resulting in prolonged and indiscriminate use of antimicrobial agents.