• Biomedical Science Letters
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• v.10 no.4
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• pp.501-506
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• 2004

Extended spectrum β-lactamase (ESBL) generated Enterobacteriaceae including Escherichia coli is responsible for resisting antibiotics, which is clinical problem. This study was performed to investigate the isolation rates of 111 strains having positive of VITEK ESBL test 111 ESBL-strains in each month and season and statistically to determine their patterns of antibiotic test. One hundred eleven ESBL-strains were collected among 1,688 strains of E. coli isolated from various clinical specimen of one general hospital in Busan during 2002 to 2003. Month rates of ESBL-strains were 0％ to 13.3％, while the seasonal rates were highest at autumns during two years. The resistance to ampicillin, cefazolin, azteronam, ceftriaxone, and cefepime were 100％ in 2002. In ampicillin and cefazolin the resistances were 100％ during the two years. There were significant differences of cefoxitin and piperacillin/tazobactam between the two years but not significant between specimens. Four groups were divided according to the pattern of resistance and then the highest group had 93∼100％ of the resistance to 8 drugs but not resistant to imipenem.

• Fisheries and Aquatic Sciences
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• v.25 no.4
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• pp.202-213
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• 2022

Antibiotic resistant Escherichia coli cases are increasing high especially in Southeast Asia. Illegal use of the antibiotic in the aquaculture farming may become the culprit of the outbreak and spread into environmental source. A study was conducted to: 1) detect the chloramphenicol (CAL)-resistant gene in E. coli isolated from three aquaculture farms and six rivers of northwestern Borneo and 2) investigate the correlation between cat gene with five common antibiotics used. Isolation of E. coli was done on Eosin methylene blue agar and characterized using indole, methyl red, Voges-Proskauer, citrate tests. E. coli isolates were subsequently tested for their susceptibility to five antibiotics commonly used in aqua-farming. The CAL-resistant E. coli were further analyzed for the presence of resistant genes (cat I, cat II, cat III, cat IV) using multiplex polymerase chain reaction. 42 bacterial colonies were isolated from a total of 80 individual water samples, 34 of which were identified as E. coli. Result showed 85.3% of the E. coli isolates were resistant to amoxicillin, 35.3% were resistant to tetracycline, 29.4% were resistant to CAL, 17.6% were resistant to nitrofurantoin and 8.8% were resistant to nalidixic acid. All of the 10 CAL resistant E. coli isolateswere detected with cat II genes; five isolates detected with cat IV genes; three isolates detected with cat III genes; and another two detected with cat I genes. Pearson correlation coefficient shows highly significant relationship between resistance pattern of CAL with amoxicillin; and CAL with tetracycline. Our findings provide the supplementary information of the CAL resistance gene distribution, thereby improving our understanding of the potential risk of antibiotic resistance underlying within this microbial ecosystem.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.2
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• pp.85-92
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• 2018

Information on the prevalence of S. aureus and the current antimicrobial resistance profile is necessary in selecting the appropriate treatment of S. aureus infections in any part of the world. This study examined the frequency and antibiotic resistance list of S. aureus isolates obtained from clinical specimens at one hospital in Korea. A total of 1,746 gram positive cocci collected were identified as S. aureus. S. aureus isolates were obtained from different samples including sputum (N=565; 32.4%), endotracheal aspirate (358; 20.5%), wounds (329; 18.8%), blood (137; 7.8%), urine (67; 3.8%), and pus (59; 3.4%). All 1,545 S. aureus (100%) strains screened from sputum (565; 36.6%), endotracheal aspirate (388; 25.1%), wounds (329; 21.3%), blood (137; 8.9%), urine (67; 4.3%), and pus (59; 3.8%) were sensitive to glycopeptide (vancomycin, teicoplanin), oxazolidinone (linezolid) and stretogramin (quinupristin/dalfopristin). The prevalence of resistant S. aureus was significantly (P<0.01) lower in urine, blood, pus, wounds, and sputum than in endotracheal aspirates. As a result, there was a significant difference in the antibiotic resistance of S. aureus according to the clinical specimens.

• Journal of Food Hygiene and Safety
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• v.36 no.6
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• pp.520-527
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• 2021

In this study, toxin gene and antibiotic resistance of food poisoning strains isolated from indoor air in the cafeteria were analyzed to prevent food poisoning. Staphylococcus aureus (16 strains) and Bacillus cereus (37 strains) isolated from indoor air in child care center were tested. The toxin genes of S. aureus and B. cereus were detected by PCR assay. The antimicrobial susceptibility test followed the disc diffusion method described by the Clinical and Laboratory Standard Institute. The seg and sei toxin genes were detected in 11 of 16 S. aureus strains (68.6%). The nheA and nheB toxin genes were detected in 37 B. cereus strains. In this study, a total of 12 toxin gene patterns of B. cereus were found, among which the nheA-nheB-nheC toxin gene was found to be the most frequent pattern. The result of the antimicrobial susceptibility test of S. aureus revealed 93.8% and 87.5% resistance to ampicillin and penicillin antibiotics, but methicillin resistance S. aureus and vancomycin resistance S. aureus were not detected. All 37 B. cereus tested in this study were resistant to ampicillin and penicillin antibiotics. Based on the result of this study, it was judged that regular ventilation and air quality management were necessary to prevent food poisoning caused by S. aureus and B. cereus contaminated in the indoor air of child care centers.

• Korean Journal of Veterinary Research
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• v.17 no.1
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• pp.1-4
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• 1977

Two hundred and twenty-seven strains of Escherichia coli isolated from 25 hens (12 hens received tetracycline neomycin and sulfadimethoxine, and 13 hens not received antibiotics) were studied for the drug resistance and distribution of R factors. About 74 per cent of E. coli strains isolated from hens of a herd received antibiotics were resistance to tetracycline (TC) streptomycin (SM), chloramphenicol (CM), kanamycin (KM), ampicillin (AP) and sulfisomidine (Su), alone or in combination thereof, but only a hen among a herd not received antibiotics excreted E. coli resistant to TC and SM. Among resistant strains, about 7% were found to be resistant to TC and SM, whereas 93% were resistant to three or more antibiotics. The most common pattern was the quadruple resistant to SM, TC, KM and Su (28.7%), and followed by triple ones to SM, TC and Su (25.3%), and SM, TC and KM (24.7%). About 84% of resistant strains carried R factors which were transferable to the recipient by conjugation.

• Journal of Life Science
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• v.11 no.3
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• pp.266-272
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• 2001

A total of 79 Salmonella spp. were isolated from Pusan area in 2000. The serotypes of 79 Salmonella isolates were classified as 42 strains of S. typhi(53.1%), 24 strains of S. enteritidis(30.4%), 9 strains of S. montevideo(11.4%), 2 strains of S. typhimurium(2.5%), 1 strain of S. infantis(1.3%) and 1 strain of S. indiana(1.3%) strains(16.5%) of Salmonella sp. were isolated at May July, respectively. The isolates of S. typhi were sensitive to most sntibiotics except streptomycin. All isolates of S. typhi were especially sensitive to tobramycin, gentamicin, colistin, kanamycin, samikacin, sulfamethozazole/ trimethoprim, cefriaxone, ceftazdime, cifrofloxacin, cefoxitin and cefotaxime. Isolates of S. enteritidis wer presented higher resistance than isolates of S. typhi. Twenty-four strains of S. enteritidis were sensitive to kanamycin, amikacin cifrofloxacin, cefoxitin and cefotaxime, however 13 strains(54.2%) of S. enteritidis were resistant to carbenicillin, ampicillin and ticarcillin. Nine strains of S. montevideo were sensitive to most antibiotics except carbenicillin and streptomycin. Each 1 stain of S. indiana and S. infantis was sensitive to most antibiotics used in this study except streptomycin. Three kinds of resistant pattern (CB, SM, TE, AM, TC). In the case of S. enteritidis isolates, 9 kinds resistant pattern were detected. Most frequent resistant pattern of S. enteritidis isolates was CB, AM, TC type(16.7%)

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.659-664
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• 2010

The present study was to investigate the effect of the transition from conventional to organic dairy farming on the antimicrobial resistant pattern of pathogens in milk. A farm with tie-stall management, with an average herd size of 20 milking cows, was selected based on the owner' willingness to accept, for at least 6 months, the highly restricted protocol developed in this study. Comparisons of bacterial isolates and antimicrobial susceptibilities before changing to an organic farm system (BEFORE) and for 6 months after (AFTER) operating the experimental organic farm system were performed by Fisher's Exact Chi-square tests. Significant levels were defined at p<0.05. During the AFTER period, average frequency of antibiotic treatment was decreased from more than 3 cases/month to less than 1 case/month during which the antibiotic use was authorized only by the veterinarian. In total, 92 and 70 quarter milk samples from 24 and 18 cows during BEFORE and AFTER, respectively, were included in the study. Overall, isolates ranged from a non-resistant level for cephazolin to a very high resistant level to streptomycin (64.71% to 95.45%). Percentages of antimicrobial resistant isolates during BEFORE were significantly higher than during AFTER for ampicillin (43.48% and 5.88%, respectively) and streptomycin (95.45% and 64.71%, respectively). In conclusion, percentages of antimicrobial resistant isolates were decreased after 6 months of operating as an organic farm system.

• Korean Journal of Veterinary Research
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• v.50 no.4
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• pp.285-295
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• 2010

Protein expression patterns in Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) strains with diverse phenotypes, such as phage type, antibiotic resistance pattern and plasmid profiles were examined. For detailed analysis of proteins expressed by different S. Typhimurium strains, protein fractions were divided into detergent-rich phase (DP) and aqueous phase (AP) using triton X-114 detergent. The two phases were subjected to two-dimensional gel electrophoresis (2-DE), followed by protein identification using peptide mass fingerprinting (PMF). In the results, PMF showed that DP fractions consisted mainly of outer membrane proteins, whereas the AP fractions included cytosolic proteins. Comparison of 2-DE profiles of DP did not show any distinct protein spots which could be correlated with phage type, antibiotic resistance pattern or plasmid profile. However, comparisons of 2-DE profiles of the AP revealed differences in the protein spots, which could be correlated with the plasmid profile and phage types. Among these protein spots, flagellin was specific for strains containing a 90 kb plasmid. Compared to DT193 phage type, three protein spots in the range of pI 5.0-5.5 and MW 8-15 kDa of AP 2-DE profiles were absent in the DT104 phage types. Additionally, a protein spot with PI in the range of 4.5-5.0 and molecular weight (MW) between 51-69 kDa was specific for phage type DT104, while a protein spot with pI in the range of 4.0-4.8 and MW between 18-20 kDa was specific for DT193 phage type. These protein spots may be useful for discriminating phage types of S. Typhimurium.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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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.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.63-67
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• 2012

Antibiotic resistance in animal isolates of enterococci is a public health concern, because of the risk of transmission of antibiotic-resistant strains or resistance genes to humans through the food chain. This study investigated phenotypic and genotypic resistances profile of tetracycline in 245 $Enterococcus$ isolates from bovine milk. A total of 245 enterococci were isolated from 950 milk samples. The predominant strain was $E.$ $faecalis$ (n = 199, 81.2%) and $E.$ $faecium$ (n = 25, 10.2%). $E.$ $avium$ (n = 7, 2.9%), $E.$ $durans$ (n = 6, 2.5%), $E.$ $gallinarum$ (n = 4, 1.6%), and $E.$ $raffinosus$ (n = 4, 1.6%) were also isolated. Of the 245 enterococcal isolates 76.3% (n = 187) displayed tetracycline resistance (${\geq}16{\mu}g/ml$). Of the 187 tetracycline-resistant isolates, 83.4% (n = 156), 16.1% (n = 30), and 26.7% (n = 50) possessed the genes $tet$(M), $tet$(L), $tet$(S) respectively. While 3.2% (n = 6) of the tetracycline-resistant isolates possessed all three genes $tet$(M) + $tet$(L) + $tet$(S), 8.6% (n = 16), 16.0% (n = 30), and 2.7% (n = 5) of them possessed two genes $tet$(M) + $tet$(L), $tet$(M) + $tet$(S), and $tet$(L) + $tet$(S) respectively. The tetracycline resistance pattern investigated in this study was attributable mainly to the presence of $tet$(M).