• Korean Journal of Veterinary Research
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• v.15 no.1
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• pp.83-91
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• 1975

A total of 119 raw milk samples from ten dairy farms were examined for total bacterial count, and 739 quarter milk samples of 118 dairy cows of 14 herds were examined for mastitis. The results obtained were as follows: 1. The mean of total bacterial counts of the 119 raw milk samples was 132,000 per ml. The total bacterial counts of 81 samples (68.1%) were under the standard of 100,000 per ml and those of the 38 samples (31. 9%) were over the standard. The number of bacteria showed a tendency to increase in summer. 2. One hundred and ninety five quarters (26.4%) of 98 cows (52.7%) were proved to be infected with mastitis. Clinical mastitis was found at 7 qtarters (3.5%) of 5 cows (5.0%). 3. Staphylococcus (44.9%) and Streptococcus (26.7%) were two main causative organisms of mastitis. Coliform bacteria (4.6%), Pseuedomonas spp. (4.6%), yeasts (1. 3%) and corynebacterium sp. (0.7%) were also isolated from the infected quarters. 4. The isolates were more sensitive to chloramphenicol ((96.1%), leukomycin (78.8%), streptomycin (75.5%) and tetracycline (72.4%). On the other hand, they were less sensitive to colistin (11.0%), oreandomycin (18.1%), sulfisoxazole (24.6%), penicilline (27.6%), kanamycin (43.3%) and erythromycin (49.7%). Especially the strains of Pseudomonas spp. isolated from the infected quarters were resistant to almost all the drugs examined.

• Korean Journal of Veterinary Research
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• v.27 no.1
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• pp.61-68
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• 1987

This study was conducted to determine the microorganisms inhabitating in cow genitalia and their antimicrobial drug susceptibility. During the period between July, 1985 and February, 1986, a total of 111 cow genitalia, 58 from Korean native and 53 from dairy cow, were sampled at three abattoirs. Gross pathological examination and bacterial isolation and identification were performed from the genital samples. In addition antimicrobial drug susceptibility test for the microorganisms isolated, some synergistic activity among drugs were examined on the major organism isolated from the cases of endometritis and pyometra. The results are summerized as follows: 1. Among the bacteria isolated from the genitalia, Staphylococcus spp., C. pyogenes, E. coli, Proteus spp., Streptococcus spp., Bacillus spp. were most frequently isolated whereas the genera of Pasteurella, Pseudomonas, Klebsiella and Yersina were detected far less frequently. 2. In Korean native cow the genera of Straphylococcus and Steptococcus were more isolated than dairy cow while in dairy cow the genera of Corynebacterium, Proteus, Escherichia were more of ten isolated than Korean native cow. 3. From cow genital organs showing lesions of endometritis and prometra, C. pyogenes was most frequently isolated, the isolation rate being 60 percent, and follow by Staphylococcus spp., Proteus spp., E. coli and Pasteurella spp. in the order. 4. Antimicrobial drug susceptibility test conducted on the major organisms isolated showed that all the isolates were susceptible to gentamicin, cephalosporin and sulfisoxazole, but resistant to tetracycline and penicillin. 5. Twenty-nine isolates of C. pyogenes were submitted to the synergistic activity test of cephalosporin, kanamycin and streptomycin with penicillin. Synergists were demonstrated in 90 percent, 31 percent and 27 percent of isolates examined by the combined use of penicillin and cephalosporin, penicillin and kanamycin, penicillin and streptomycin, respectively. About 10 percent of the isolates were found to be indifferent by the synergism test.

• Restorative Dentistry and Endodontics
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• v.28 no.6
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• pp.435-448
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• 2003

This study was performed to observe the antibacterial effect of polyphosphate (polyP) with various chain lengths (P3~P75) on virulent. invasive strains of P. gingivalis A7A1-28 and W50, and multidrug resistant E. faecalis ATCC29212. P. gingivalis strains were grown in brain-heart infusion broth (BHI) containing hemin and vitamin K with or without polyP. PolyP was added at the very beginning of the culture or during the exponential growth phase of the culture. Inhibition of the growth of P. gingivalis was determined by measuring the absorbancy at 540nm of the grown cells. Viable cell counts of the culture and release of intracellular nucleotide from P. gingivalis were measured. E. faecalis was grown in plain BHI with antibiotics alone or in combination with polyP(calgon: 0.1~1.0%) and the bacterial absorbancy was measured. The overall results suggest that polyP has a strong antibacterial effect on the growth of the virulent strains of P. gingivalis and the antibacterial activity of polyP seems largely bactericidal. accompanying bacteriolysis in which chelation phenomenon is not involved. Although polyP does not exert antibacterial activity against E. faecalis, it appears to increase antibacterial effect of erythromycin and tetracycline on the bacterium. Therefore, polyP alone or in combination with antibiotics may be developed as a candidate for the agent controlling oral infections including endodontic infection.

• Korean Journal of Microbiology
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• v.50 no.2
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• pp.101-107
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• 2014

Community-acquired antimicrobial resistant bacteria are an emerging problem world-wide. In Korea, resistant bacteria are more prevalent than in other industrialized countries. The aim of this study was to investigate the isolation frequency of methicillin-resistant staphylococci (MRS), Pseudomonas, and Enterobacteriaceae from surrounding environment (home, colleges, public transportation system and possessions) in Seoul, and to examine the level of drug resistance to 13 antimicrobial agents, which are in wide spread clinical use in Korea, as well as new agent, tigecycline in Enterobacteriaceae isolates. Of total 239 samples, 18 (7.5%) MRS, 10 (4.2%) Pseudomonas, and 30 (12.6%) Entarobacteriaceae were isolated. A total of 5 (2.1%) methicillin-resistant S. aureus (MRSA) were detected in home (2 samples), colleges (1 sample), and et cetera (2 sample). A total of 5 (2.1%) Escherichia coli were detected in in home (1 samples), public transportations (3 sample), and et cetera (1 sample). Resistance to cephalosporins, fluoroquinolones, carbapenems, ${\beta}$-lactams, tetracyclines, and aminoglycosides was found in 71.9%, 71.9%, 68.8%, 68.8%, 50.0%, and 25.0% of 32 Enterobacteriaceae isolates, respectively. Also, resistance rate to trimethoprim/sulfamethoxazole of the isolates was a 43.8%. Moreover, 59.4% of the isolates were resistant to new agent, tigecycline and resistance to all agents tested was observed in 3 isolates. Five E. coli isolates were resistant to most of the agents tested, but some of them were susceptible to ciprofloxacin and gentamicin. This study can serve as a data point for future comparisons of possible changes in antibiotic resistance levels in surrounding environment. And multilateral strategies for preventing the incidence and spread of antibiotic resistance are needed.

• Korean Journal of Veterinary Service
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• v.35 no.4
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• pp.295-305
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• 2012

The aim of this study was to isolate microorganisms from half milk samples of dairy goats by California mastitis test (CMT) during the lactation period and to further investigate the susceptibility of isolated organisms to antimicrobial drugs. From a total of 235 half milk samples with CMT scores of 2 or above from 366 dairy goats distributed throughout Jeonnam province, microorganisms were isolated from 198 (83.5%) samples either singly (99.0%) or in combination (1.0%). The most prevalent microorganism was the coagulase-negative Staphylococcus spp., (44.4%, n=88) followed by Staphylococcus aureus (24.2%, n=48), Escherichia coli (11.1%, n=22) and Streptococcus spp. (7.6%, n=15). Isolated bacteria also included Bacillus spp. (2.5%, n=5), Pseudomonas spp. (2.5%, n=5), Micrococcus spp. (1.5%, n=3), Corynebacterium spp. (1.5%, n=3), Enterococcus facium (1.0%, n=2), Morganella morganii (0.5%, n=1) and Streptococcus agalactiae (0.5%, n=1). During the summer season, a high prevalence of all microorganisms were observed in which Staphylococcus spp. (30.8%), Escherichia coli (8.6%), and Streptococcus spp. (5.6%) were among the most prevalent bacteria isolated. Staphylococcus spp. was also shown to be high in the winter (21.7%). In most samples, the presence of bacterial pathogens in goat milk led to the increase in the total somatic cell count (SCC). Most of the half milk samples of dairy goats with bacterial contamination showed SCC of ${\geq}1{\times}10^6cells/ml$ (90.4%). Minor pathogens (11.4%) were more detected from milk samples with SCC of < $1{\times}10^6cells/ml$ than major pathogens (4.1%), while the major pathogens tended to be higher from samples with SCC of ${\geq}3{\times}10^6cells/ml$. Susceptibility of these bacteria to 12 antimicrobial agents was tested by the Kirby-Bauer disc diffusion method. Results indicated that more than 90% of bacteria isolated from CMT 2+ dairy goat half milk samples were susceptible to trimethoprim/sulfamethoxazole, amoxicillin/clavulanic, enrofloxacin and cephalothin while they were resistant to tetracycline (44.7%).

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.361-368
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• 2011

The growth rate of piglets will be decreased and the mortality of piglets will be increased in the postpartum sow with mastitis. The aim of this study was to isolate microorganisms from milk samples found in postpartum sows with suckling piglets and to further investigate antimicrobial susceptibility against isolated bacteria. Milk samples were collected from 567 udders of 42 lactating sows and the isolated bacteria was then identified. Isolated bacteria were tested with 12 antimicrobial agents. Bacteria were isolated from 260 milk samples (64.5%). Staphylococcus spp. were the most common microorganisms (74.5%) isolated from sow milk, followed by Streptococcus hyicus (53.9%), Staphylococcus epidermis (11.8%), Staphylococcus aureus (9.8%), and Staphylococcus haemolyticus (53.9%). In the Staphylococcus spp., Streptococcus pneumoniae (5.1%) was isolated as was Streptococcus sanguinis (3.8%) and Streptococcus ovis (2.9%). Results indicated that bacteria isolated from healthy sow milk were mostly susceptible to cephalothin (88.0%), amikacin (85.3%) and cefoxitin (82.4%), but were resistant to streptomycin (10.0%), kanamycin (33.1%) and tetracycline (19.6%).

• Journal of fish pathology
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• v.30 no.2
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• pp.89-96
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• 2017

The majority of freshwater ornamental fish are imported and distributed domestically, causing high risk of exposure to exotic pathogens and drug resistant bacteria in Korea. Aeromonas hydrophila is known as a common species of fresh water bacteria and opportunistic fish pathogen, as well as a species causing zoonotic infection. In this study, we isolated motile aeromonads from various imported freshwater ornamental fish and studied the characters of the isolates. Imported freshwater ornamental fish were purchased on day 1 after the fish were deposited in the aquarium. Bacteria were isolated from the liver, kidney and spleen of fish using 0.5% NaCl containing tryptic soy agar medium. Bacteria were grouped on the basis of their morphological characteristics. The colonies with clear zone on starch-ampicillin agar (SA agar) were tentatively identified as Aeromonas spp. Two hundred and twenty-six strains, about 70% of total isolates were assumed to be Aeromonas spp. Nine isolates were further identified based on the result of the API 20E test and PCR using primers specific for A. hydrophila 16S rRNA gene. The isolates were identified as A. hydrophila and the API 20E test showed differences in trisodium citrate, D-sucrose, D-melibiose, amygdalin and L-arabinose availability between the nine isolates and standard A. hydrophila. The susceptibilities of the isolated bacteria to 10 antibacterial agents were confirmed by the disk diffusion method. Isolated strains were found to be resistant to amoxicillin and ampicillin and sensitive to florfenicol. However, 7 isolates showed multiple drug resistances to erythromycin, oxytetracycline, nalidixic acid etc. Pathogenicity of the isolates was determined by the artificial challenge test on goldfish (Carassius auratus). Three isolates caused 60 ~ 80% mortality in goldfish within 5 days after the initiation of challenge. These results indicate that multiple drug resistant, highly pathogenic and exotic A. hydrophila can spread to domestic aquarium and the preventive treatment of fish before sale is necessary.

• Journal of Food Hygiene and Safety
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• v.25 no.2
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• pp.122-128
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• 2010

From April to December in 2009, microbial investigation is accomplished for 100 frozen foods asked to microbial control team that corresponds with total aerobic viable bacteria, coliform group, Escherichia coli, Enterococcus spp. and antibiotic resistance patterns of Enterococcus spp. isolates are investigated. Average of total erobic viable bacteria numbers is $4.3{\times}10^4CFU/g$. Average of coliform group numbers is $4.3{\times}10^3CFU/g$. Average f Enterococcus spp. numbers is $1.8{\times}10^3CFU/g$. Escherichia coli from 100 frozen foods is not detected and detection ate is 0.0%. 22 Enterococcus spp. are isolated from 100 frozen foods. 12 of 22 Enterococcus spp. strains are identified as E. faecium. 7 of 22 Enterococcus spp. strains are identified as E. faecalis. 2 of 22 Enterococcus spp. trains are identified as E. gallinarum. 1 of 22 Enterococcus spp. strains is identified as E. hirae. Enterococcus spp. solates show a high resistance to erythromycin, rifampin, tetracycline, ciprofloxacin, chlorampenicol, penicillin and susceptibility to vancomycin, ampicillin, gentamicin, strepomycin, linezolid. 15 of 22 Enterococcus spp. strains are multi-resistant and the most frequent multi-resistant pattern is erythromycin-rifampin for 6 Enterococcus spp. strains.

• The Plant Pathology Journal
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• v.15 no.3
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• pp.137-143
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• 1999

A novel chromosomal gene tagging technique using a specific fragment of the fatty acid desaturase-like open reading frame (des-like ORF) from the tox-argK gene cluster of Pseudomonas syringae pv. phaseolicola was developed to identify Xanthomonas spp.released into the environment as biocontrol agents. X. campestris pv. convolvuli FB-635, a pathogen of Convolvulus arvensis L., (bindweed), was chosen as the organism in which to develop and test the system. A 0.52 kb DES fragment amplified from P. syringae pv. phaseolicola C-199 was inserted into pGX15, a cosmid clone containing a 10.3 kb Eco RI-HindIII fragment derived from the xanthomonadin biosynthetic gene cluster contained in plasmid pIG102, to create a pigG::DES insertion. The 10.8 kb EcoRI-BamHI fragment carrying the pigG:: DES insertion was cloned into pLAFR3 to generate pLXP22. pLXP22 was then conjugated into X. campestris pv. convolvuli FB-635 and the pigG::DES insertion integrated into the bacterial chromosome by marker exchange. Rifampicin resistant, tetracycline sensitive, starch hydrolyzing, white colonies were used to differentiate the marked strain from yellow pigmented wild-type ones. PCR primers specific for the unique DES fragment were used for direct detection of the marked strain. Result showed the marked strain could be detected at very low levels even in the presence of high levels of other closely related or competitive bacteria. This PCR-based DES-tagging system provides a rapid and specific tool for directly monitoring the dispersal and persistence of Xanthomonas spp.released into the environment.

• Environmental Engineering Research
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• v.25 no.4
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• pp.614-621
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• 2020

Antibiotic pollution is one of the factors contributing to the spread of antibiotic-resistant bacteria in the environment. Advanced oxidation and irradiation processes have been introduced to eliminate antibiotics from water and wastewater. However, few studies have reported the toxic effects of residual antibiotics and their byproducts induced by a treatment system. In this study, we compared the efficacies of chemical (high-performance liquid chromatography (HPLC)) and biological (antimicrobial susceptibility test) assays for measuring the concentrations of residual antibiotics after gamma irradiation for degrading amoxicillin, cephradine, lincomycin, and tetracycline. The concentrations of residual antibiotics estimated using the two assay methods were almost identical, except cephradine. In the case of cephradine, inhibited bacterial growth was observed that was equivalent to twice the concentration measured by HPLC in the samples subjected to gamma irradiation. The observed inhibition of bacterial growth suggested the generation of potentially toxic intermediates following antibiotic degradation. These results indicate that biological and chemical assays should be used in concert for monitoring antibiotic contamination and the toxic derivatives of antibiotic degradation. The results demonstrate that these four antibiotics can be decomposed by 2.0 kGy gamma-irradiation without toxic effects of their byproducts.