• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.232-239
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• 2009

This research investigated the characteristics of antibiotic resistance of bacteria in microbial communities from municipal wastewater treatment plants (MWTPs), and monitored seasonal changes of antibiotic resistant bacteria (ARB) from MWTPs and Han river. When antibiotics were amended to either R2A agar (R2A) for general heterotrophs or MacConeky sorbitol agar (MSA) for coliform bacteria, all the MWTP samples exhibited multiple antibiotic resistance on the antibiotic-amended solid media. The antibiotic resistance appearing frequencies of ampicillin and sulfathiazole, respectively, were higher than reported data for other countries. The antibiotic resistance appearances differed depending upon the concentrations of primary substrate and nutrients and the types of cultivation media. The following 16S rRNA gene phylogenetic analysis showed that the identified multiple-antibiotic resistant microbes on R2A plates were more likely to be known human-pathogenic bacteria than the background heterotrophic bacteria were, suggesting a high risk of antibiotic resistance appearance to public health. In addition, according to our investigation of seasonal changes of ARB from urban MWTP and river samples, the frequency of ARB appearances was shown to correlate positively with temperature. This indicates a possibility that global warming result in increase in microbial risk to public health.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.709-717
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• 2015

Airborne bacteria from hog farms may have detrimental impacts on human health, particularly in terms of antibiotic resistance and pathogen zoonosis. Despite human health risks, very little is known about the composition and diversity of airborne bacteria from hog farms and hog-related spray fields. We used pyrosequencing analysis of 16S rRNA genes to compare airborne bacterial communities in a North Carolina hog farm and lagoon spray field. In addition, we isolated and identified antibiotic-resistant bacteria from both air samples. Based on 16S rRNA gene pyrosequence analysis, Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were the dominant phyla in airborne bacterial communities from both hog farm and spray field sites. Within the Firmicutes genera, Clostridium spp. were more abundant in the hog farm, whereas Staphylococcus spp. were higher in the spray field. The presence of opportunitic pathogens, including several Staphylococcus species and Propionibacterium acnes, was detected in both bioaerosol communities based on phylogenetic analysis. The isolation and identification of antibiotic-resistant bacteria from air samples also showed similar results with dominance of Actinobacteria and Proteobacteria in both hog farm and spray field air. Thus, the existence of opportunistic pathogens and antibiotic resistant bacteria in airborne communities evidences potential health risks to farmers and other residents from swine bioaerosol exposure.

• Korean Journal of Food Science and Technology
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• v.52 no.3
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• pp.296-303
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• 2020

Hop-resistant lactic acid bacteria (LAB) are well-known, major beer-spoilage bacteria. The hop-gradient agar containing ethanol (c-HGA+E) method has been used to examine hop-resistance of beer-spoilage LAB. However, the selection of beer-spoilage bacteria by the c-HGA+E method is either too selective or too inclusive. Furthermore, it is accompanied by a complicated experimental procedure, high-cost and time. To overcome these disadvantages, the modified hop-gradient agar with ethanol (m-HGA+E) method was developed. The most remarkable modifications were the shape of the petri dish and the inoculation method for bacteria. The efficiency and validation of the m-HGA+E approach were proven by the formation of colonies at different hop concentrations in the bottom layer, co-culture with the bacteriocin producer and by PCR detection of hop-resistant genes. This study demonstrated that m-HGA+E is a rapid, economical, and easy method to monitor potential hop-resistant beer-spoilage LAB during the beer brewing process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.413-419
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• 2021

The purpose of this study was to investigate the ability to treat and prevent infection by multiple Gram-negative bacterial pathogens as a last choice option in the treatment of serious infections in clinical settings. The global spread of extended-spectrum 𝛽-lactamases (ESBLs) and/or carbapenemases in microorganisms are of enormous concern to health services because they are often associated with multi-drug resistance which significantly restricts the antibiotic treatment options. In this study, the antimicrobial resistance profiles of bacteria isolated from South Korean market-derived meat samples were determined by the disc diffusion method. PCR was used to detect the presence of antibiotic resistance genes and ESBL producing genes. In total, we tested 181 isolated colonies from 36 market-derived meat samples. Single PCR and DNA sequencing results revealed that genes blaVIM, blaBIC, blaKPC, and blaSIM were present in the bacteria isolated from retail meat. The bacteria in the meat were separately sequenced and based on alignment, four different bacteria were identified. These findings suggest that bacteria found in retail meats are a reservoir for the spreading of ESBL blaVIM, blaBIC, blaKPC, and blaSIM resistance genes and bacteria strains.

• Korean Journal of Veterinary Service
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• v.32 no.1
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• pp.33-41
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• 2009

In order to develop probiotic strain for pigs, Lactobacillus spp. (527 isolates), Streptococcus spp. (95 isolates) and Bifidobacterium spp. (25 isolates) were isolated from the feces of 35 pigs. These isolates were tested through in vitro experiment such as acid tolerance at pH 2.0 (Lactobacillus spp. and Streptococcus spp.) or pH 3.0 (Bifidobacterium spp.), bile tolerance in MRS broth containing 0.3% (w/v) Oxgall, heat resistance at $70^{\circ}C$ and $80^{\circ}C$ for 5 min, antibiotic resistance, antimicrobial activity against pathogenic bacteria and Caco-2 cell adherence assay. Finally ten most superior strain (5 Lactobacillus spp. strain, 3 Bifidobacterium spp. strain and 2 Streptococcus spp. strain) were selected as potential candidate for probiotic use in pig industry. It could be used as an alternative to antibiotics in feed additives.

• Journal of Environmental Health Sciences
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• v.39 no.5
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• pp.447-455
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• 2013

Objectives: This study aims to understand the concentration, diversity, and antibiotic characteristics of staphylococci present in the indoor air of child-care facilities. Methods: Air sampling was performed from October 2012 to January 2013 in 120 child-care facilities in Seoul, Korea. Methicillin-resistant bacteria were selected from the total obtained airborne bacteria and subjected to 16S rRNA analysis for methicillin-resistant staphylococcal species determination. Identified staphylococcal strains were tested for resistance to a range of antibiotics. Results: Average total airborne bacterial concentration was $508.9{\pm}246.3CFU/m^3$. Indoor concentration of total airborne bacteria had a significant positive correlation with the $CO_2$ concentration in the child-care facilities. Methicillin-resistant staphylococci were present in 13.3% of the child-care facilities studied. A total of four species (S. epidermidis, S. cohnii, S. saprophyticus, S. sp.) and 55 strains were identified from the indoor air of the child-care facilities. Staphylococcus cohnii was the most common species (54.5%), followed by S. epidermidis (38.2%). All of the isolated staphylococcal strains exhibited high resistance to oxacillin, erythromycin, mupirocin, and ceftizoxime. Especially, S. saprophyticus strains showed more multidrug resistance to oxacillin, vancomycin, clindamycin, erythromycin, lincomycin, ceftizoxime, mupirocin, and tetracycline than did other species. Conclusion: The results of this study showed that a monitoring system for multidrug-resistant bacteria is needed in facilities for children, as the community-associated infections of these bacteria are increasing.

• Journal of fish pathology
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• v.37 no.1
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• pp.133-138
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• 2024

This study is a report on combinational effects between four sesquiterpene lactones (SLs) from bay laurel (Laurus nobilis) leaves, and oxytetracycline (OTC) or amoxicillin (AMX) against four fish pathogenic bacteria such as Vibrio anguillarum, V. harveyi, Edwardsiella tarda, and Streptococcus iniae. Individually, four SLs exerted little antibacterial activity against fish pathogenic bacteria. However, when combined with OTC or AMX, they showed synergistic interaction against pathogenic bacteria. Especailly, zaluzanin C (1) reduced the MIC of OTC (or AMX) eight-fold. Our results showed that combinations of SLs with antibiotics (ABTs) are more effective than ABTs alone to control pathogenic bacteria. The highest synergistic effect was observed when zaluzanin C (1) was combined with OTC or AMX against V. harvey or S. iniae, displaying significant reductions of MICs up to 8-fold (0.125 to 0.015 ㎍/mL and 0.0078 to 0.0009 ㎍/mL). In addition, zaluzanin C (1) improved the antibiotic potency of OTC against OTC resistant V. harveyi (250 ㎍/mL to 62.5 ㎍/mL). Synergism between ABTs and phytochemical such as SLs could be a therapeutically helpful concept to improve the efficacy of ABTs and prevent antibiotic resistance. These results suggest that SLs can be used as an alternative to reduce antibiotic resistance in aquaculture.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.356-358
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• 2011

• YAKHAK HOEJI
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• v.30 no.1
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• pp.51-54
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• 1986

Fecal samples from Kim-Hae farm animals were examined for the frequency of gram-negative enteric organisms resistant to tetracycline, streptomycin, or penicillin. The propertions of antibiotic resistant to total organisms in fecal specimens of poultry, swine and cow were as follows: 95%, 92%, 70% for tetracycline, 100%, 27%, 9% for streptomycin, 18%, 1%, 1% for penicillin, respectively. The bacteria had multiresistance to antibiotics. These strains had more than one plasmid. From the transformation study, it was concluded that the resistance to streptomycin was attributed to one of these plasmids.

• Korean Journal of Microbiology
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• v.29 no.1
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• pp.63-68
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• 1991

Several arsenic compound-resistant bacteria were isolated from Jung-Rang stream. The isolates, D-3, D-12, and D-14 were characterized phenotypically and genetically, and identified as Serratia liquefaciens, Klebsiella oxytoca, and Klebsiella pneumoniae, respectively. A plasmid of 67kb was found in Klebsiella oxytoca D-12 and designated as pMH12. Transfer of this plasmid from D-12 to E. coli HB101 was occurred, and the resulting transconjugant strains expressed the same level of heavy metal resistance as the donor strain. The physical presence of this plasmid in transconjugant was detected with agarose gel electrophoresis. Arsenite-sensitive derivatives of isolate D-12 were obtained with Mitomycin C treatment which cured pMH12. Antibiotics and heavy metal resistances were also examined to be used as a proper marker for the isolates in gene cloning. Isolate D-12 has resistance to several heavy metal ions such as $Cd^{2+}$ , $Zn^{2+}$ and $Hg^{ 2+}$ Also, all the other arsenite resistant isolates showed resistance to several heavy metal ions and antibiotics.