• The Korean Journal of Food And Nutrition
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• v.12 no.6
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• pp.564-568
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• 1999

Habituation to alkali condition and susceptibility to antimicrobial agents were investigated to determine methods t inactivation Escherichia coli O157:H7 associated with food poisoning. The investigation showed that Escherichia coli O157:H7growth at pH 9.0 The susceptibilities of Escherichia coli O157:H7 to 13 drugs examined were found highest in regad to saicin and ceftriaxone and lowest in regard to erythromycin and josamycin. No significant changes in minimal inhibitory concen-tration(MIC) values of bactericidal effect was found when saicin and ceftriaxone were irradiated with doses of 5-100KGy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.85-93
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• 2017

The urinary tract infection (UTI) is one of the most important infections in hospital. The overuse and misuse of antimicrobial agents and the resulting emergence of resistant microorganisms have made choices regarding antimicrobial therapy more difficult. This study examined the changes in the antibiotic susceptibility to the causative organisms of urinary tract infections to provide useful information on the choice of adequate drugs in the treatment of urinary tract infections. The medical records of 2,707 patients with more than $10^5/ml$ microorganism in urine culture between January 2010 and December 2015 were reviewed retrospectively. The most common pathogenic organism was E. coli (28.1%). In the case of E.coli, there were no differences in frequency from 2010 to 2015 in men, but since 2014, the frequency decreased gradually since 2014 in women. For E. coli, the resistance rates to antibiotics were 72.2% in ampicillin, 44.9% in trimethoprim/sulfamethoxazole (TMP/SMX), and 41.3% in ciprofloxacin, but the 2nd, 3rd, and 4th cephalosporin (5%) had low antibiotic resistance rates. The pathogens of urinary tract infection are becoming diverse and their frequencies are also changing over time. These results suggest that the recommended drugs for UTI should be selected more carefully for in-patients and out-patients.

• 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.28 no.1
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• pp.71-79
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• 2005

In this study, a total of 2,119 samples was taken from bovine feces and carcass from March 2002 to December 2003. And those were examined for the presence of enterohemorrhagic E coli O157:H7. The properties of the isolates were characterized for biochemical features, serotypes, virulence genes and antimicrobial susceptibility. Forty five strains($3.7\%$) of E coli O157:H7 were isolated from 1,208 fecal samples and were not detected in carcass using immunomagnetic separation technique and selective media. In multiplex PCR using stx1, stx2, eaeA and hlyA primers, the amplified bands at 180 bp, 255bp, 384bp and 534bp were observed, respectively. In antimicrobial susceptibility test, all isolates were susceptible to amoxicillin/clavulanic acid and cefazolin. The isolates were most resistant to sulfisoxazole($24.4\%$), followed by streptomycin($22.2\%$), tetracycline($20.0\%$). Eight strains($17.8\%$) of 45 isolates showed the multi-resistant patterns with over 3 drugs.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.668-679
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• 2023

Edwardsiella tarda is one of the most significant fish pathogens, causes edwardsiellosis in a variety of freshwater fish species, and its antibiotic resistance against multiple drugs has made it a health risk worldwide. In this study, we aimed to investigate the antibiotic resistance (ABR) genes of E. tarda and establish its antibiotic susceptibility. Thus, 540 fish (299 Oreochromis niloticus, 138 O. mossambicus, and 103 O. aureus) were collected randomly from twelve fish farms in three districts of Punjab in Pakistan. E. tarda was recovered from 147 fish showing symptoms of exophthalmia, hemorrhages, skin depigmentation, ascites, and bacteria-filled nodules in enlarged liver and kidney. Antimicrobial susceptibility testing proved chloramphenicol, ciprofloxacin, and streptomycin effective, but amoxicillin, erythromycin, and flumequine ineffective in controlling edwardsiellosis. Maximum occurrence of qnrA, blaTEM, and sul3 genes of E. tarda was detected in 45% in the liver, 58%, and 42% respectively in the intestine; 46.5%, 67.2%, and 55.9% respectively in O. niloticus; 24%, 36%, and 23% respectively in summer with respect to fish organs, species, and season, respectively. Motility, H₂S, indole, methyl red, and glucose tests gave positive results. Overall, E. tarda infected 27.2% of fish, which ultimately caused 7.69% mortality. The Chi-squared test of independence showed a significant difference in the occurrence of ABR genes of E. tarda with respect to sampling sites. In conclusion, the misuse of antibacterial agents has led to the emergence of ABR genes in E. tarda, which in association with high temperatures cause multiple abnormalities in infected fish and ultimately resulting in massive mortality.

• Korean Journal of Veterinary Research
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• v.48 no.3
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• pp.295-303
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• 2008

One hundred and sixty nine Escherichia (E.) coli strains isolated from fecal samples of aquatic birds in Geumho river basin and Dalseong park were tested by agar dilution method to determine their susceptibility patterns to 14 antimicrobial agents. The distribution of tetracycline resistance determinants (tetA, tetB, tetC, tetD and tetE) were also examined by PCR in 76 tetracycline-resistant ($TC^r$) E. coli isolates. The high resistance was observed in tetracycline, cephalothin and ampicillin (45.0~36.7%). Resistance of E. coli isolates derived from Dalseong park to tetracycline, cephalothin, ampicillin and streptomycin (65.7~44.8%) were significantly higher than those isolated from Geumho river basin (31.4~14.7%). About seventy percent (70.4%) of the strains isolated were resistant to one or more drugs tested. Thirty (39.5%) of 76 $TC^r$ E. coli isolates which were resistant to one or more drugs transferred all or a part of their resistance patterns to the recipient strain of E.coli J53 by conjugation. All of $TC^r$ E. coli isolates contained at least one or more of 5 tet genes examined. The most common genes found in these isolates were tetA (60.6%) and followed by tetB (7.9%) and tetC (1.3%). However, tetD and tetE were not found in any of the isolates tested. Twenty one (27.6%) of $TC^r$ E. coli isolates had two determinants, tetA/tetB (20 strains), tetA/tetC (1 strain). And two strains (2.6%) contained three determinants (tetA/tetB/tetC).

• The Journal of the Korean Society for Microbiology
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• v.21 no.1
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• pp.17-31
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• 1986

Forty clinical isolates of Serratia marcescens were tested for their susceptibility to 19 antimicrobial drugs and studied on the molecular characteristics of R plasmids. Cefotaxime (Ct) was the most effective drug and only 2 (5%) strains were resistant to this drug. Thirteen to 18% of strains were resistant to cefoperazone (Cz), amikacin (Ak). and trimethoprim (Tp), and 28 to 40% were resistant to piperacillin (Pi), nalidixic acid (Na), gentamicin (Gm), and cefoxitin (Cx). A majority of strains were resistant to carbenicillin (Cb), tobramycin (Tp), kanamycin (Km), and cefamandole (Cd), and all to cephalothin. One half of the isolates were resistant to 10 or more drugs. $MIC_{90}$ of Pi to Gm-resistant strains (Gm') were 8 times higher than that to Gm-susceptible strains (Gm'), but $MIC_{90}$ of Ak, Cx, Ct, and Cz were almost the same between both Gm' and Gm' strains. Nine (23.7%) strains among 38 of multiply drug-resistant S. marcescens transferred conjugally their partial patterns of resistance to E. coli or Klebsiella strains, and two S. marcescens strains producing bacteriocin transferred their resistance to Klebsiella only, but not to E. coli. The plasmid profiles of S. marcescens were studied by the methods of SDS lysis and agarose gel electrophoresis. Twenty-four (60%) strains carried one to four plasmids of 1.4. to 144 Mdal, and conjugative R plasmids of 49 to 127 Mdal were noted in transconjugants. MIC levels of drugs in transconjugants were variable by the R plasmids and recipient strains.

• Korean Journal of Microbiology
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• v.22 no.1
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• pp.41-48
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• 1984

Twenty two cultures of pathogenic bacteria were isolated from cultured eels(Anguilla japonica) from Asan Hatchery. The bateria were characterized by their biochemical properties, serological relationships, infectivity to gold fish and susceptibility to various antimicrobial compounds. Fourteen of 22(64%) cultures were identified as Edwardsiella tarda, five (23%) as Aeromonas hydrophila and three (14%) as Vibro anguillarum. Edwardisiella tardo isolates proved to be the main cause of the disease in cultured eels. They were serologically homogeneous and their virulency to gold fish was higher than any of the other groups of bacteria tested. The virulence of 3 isolates were low in gold fish exposed to the bacteria by the waterborn route. Ten strains were tested for their susceptibility to 12 antimicrobial compounds and were resistant to from one to six drugs: in particular, tetracycline derivatives and sulfisoxazole.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.251-258
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• 1987

A total of 58 strains of Enterobacter species isolated from clinical specimens at Kyungpook National University Hospital in Taegu and Yonsei University Hospital in Seoul were tested for the molecular characterization to investigate the nosocomial infection through the study of R plasmids which might spread among Gram negative organisms regardless of their originated strains. All strains resistant to ampicillin, cefoxitin and cephalothin but susceptible to moxalactam were subjected to the further test for the determination of in detail MIC value against 23 drugs of common use including beta-lactam antibiotics and R plasmid profile analysis. The reistance frequency of strains against carbenicillin (53.4%) was similar to those against chloramphenicol, tobramycin, and sulfisomidine. Though the MIC values of resistance criteria against ceftazidime, aztreonam, imipenem, and norfloxacine in NCCLS manual were not available but MIC ranges of strains tested were very low. There were differences in patterns and frequencies of resistance between the strains isolated in Seoul and Taegu isolates. Seoul isolates showed a tendency of higher multiplicity of resistance than those of Taegu isolates. The resistances against cefoxitin, cephalothin, cefoperazone, cefotaxime, nalidixic acid, and rifampin were not conferred to the conjugally transferable R plasmid. The approximate molecular size of conjugally transferable R plasmids ranged 30 to 151 megadalton, and one or 2 to 3 R plasmids were identified in each transconjugants.

• Korean Journal of Veterinary Research
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• v.29 no.4
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• pp.493-501
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• 1989

A total of 108 strains of C jejuni isolated from pigs and chickens were examined for the susceptibility to 10 antimicrobial agents and normal sera of cattle, sheep, guinea pigs and chickens. Minimal inhibitory concentration(MIC) ranges of antimicrobial agents to C jejuni isolates were $${\leq_-}1.56$$ to $${\geq_-}100{\mu}g/ml$$ for erythromycin, rifampin, streptomycin and tetracycline, 50 to $${\geq_-}100{\mu}g$$ for cephalothin, $${\leq_-}1.56$$ to $50{\mu}g$ for ampicillin, $${\leq_-}1.56$$ to $25{\mu}g$ for kanamycin and nalidixic acid, $${\leq_-}1.56$$ to $12.5{\mu}g$ for chloramphenicol and gentamicin. Resistance rates of C jejuni were showed to in order of rifampin(84.7%), tetracycline(56.2 %), erythromycin(17.1%) and ampicillin(3.8%), all of the strains were sensitive to chloramphenicol, gentamicin and kanamycin, and the incidence rates of resistant C jejuni were highly frequent in pig isolates than chicken isolates. The drug resistance patterns of 87 chicken isolates C jejuni to 9 antimicrobial drugs were showed 12 patterns, and Sm Ra Tc(24.1%), Sm Ra(21.8%) and Ra Tc(14.9%) were relatively common, and also 21 pig isolates were showed 6 patterns and Em Sm Ra Tc(57.1%) were most frequent. The majority of the isolates showed multiple drug resistance. Bactericidal activity of 10% normal sera from healthy animals were examined for 60min at $37^{\circ}C$. C jejuni were decreased from 0.4 to 1.0 ${\log}_{10}$(p<0.01), and serum susceptibility were high in order of guinea pig, sheep, chicken and cattle sera. Serum sensitivity of C jejuni Ch-39 strain in increased serum concentation up to 10, 20, 40 and 80% were highly significant. In the normal animal serum, the number of Ch-39 strain were decreased from $1.8{\times}10^4/ml$ to $2.7{\times}10^3/ml$ after 60 min incubation(p<0.01), but the numbers were decreased to $6.6{\times}10^3/ml$ in the heat inactivated normal serum for 30 min at $56^{\circ}C$. Bactericidal activity was restored in the heat inactivated normal serum after the serum of complement source was added.