• 대한미생물학회지
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• 제6권1호
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• pp.21-27
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• 1971

Recent reports confirm that R factors is widespread in Korea among Enterobacteriaceae isolated from humans. However, no reports have been made concerning the incidence of transferable drug resistance in domestic animals in this country. A total of 211 isolates of Escherichia coli, including 94 strains from dogs, 76 strains from pigs, 30 strains from chickens, and 21 strains from cow milk, were examined for drug resistance and distribution of R factors. And, respective two strains of Salmonella E group and Salmonella cholerasuis which were isolated from dogs and pigs, respectively were also examined for the same purposes. Of 211 strains of E. coli isolated, 66.8% were found to be resistant to 8 antibacterial agents such as streptomycin(SM), tetracycline(TC), chloramphenicol(CP), ampicillin sodium(AP), nalidixic acid(NA), gentamicin(GM), and polymyxin B(PX). Among the isolates, 86.2% of the strains from dogs, 70% of the strains from chickens, 43.4% of the strains from pigs, and 28.6% of the strains from milk, respectively, were found to be resistant to the drugs. The following percentage of resistance of E. coli to each individual drugs was encountered: of 94 strains from dogs, AP, 64.9%; SM, 20.2%; NA, 12.8%, CP and PX, 8.5% each; GM, 2.1% each; GM, 2.1%. Among 76 strains from pigs, 42.2% and 2.6% each were resistant to TC, AP and PX, respectively. Among 30 strains from chickens, 43.3% were resistant to SM, TC, AP, respectively, and no strains were resistant to the other drugs. No strains of the isolated from milk were resistant to the drugs, except that 28.6% were resistant to SM and AP, respectively. Of the strains from dogs, multiply resistant strains(56.8%) were more than singly resistant one(43.2%) and sixteen different drug resistant patterns were observed. The most frequently encountered patterns were AP TC AP and SM CP AP NA. Of the isolates from other sources, the most frequently encountered resistant patterns were as follows: TC among the strains from pigs; SM TC AP from chickens; SM AP from milk. Of the resistant strains from dogs, 32% carried R factors and the most common resistance patterns of R factors were AP TC AP and SM TC CP, whereas 35.2% of the resistant strains from pigs carried R factors of which the most common encountered pattern was TC. Of the resistant strains from chickens, 46.9% carried R factors of which the most common patterns were SM TC TC AP and AP, whereas 50% of the resistant strains from milk carried R factors of which the most common pattern was SM. Of 4 strains of Salmonella isolated, no strains were resistant to the drugs, except that only one strain of Salmonella E group isolated from a dog was resistant to AP. The strain did not harbor R factor.

• 한국임상수의학회지
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• 제21권2호
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• pp.133-139
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• 2004

Bacterial pathogens were isolated from 36 dogs with respiratory signs, that were submitted to Veterinary Clinics in Jeju, including Veterinary Medical Teaching Hospital in Cheju National University. Of 36 isolates, 16 (44.4%) bacterial pathogens were Gram-positive and 20 (55.6%) were Gram-negative. Gram-positive bacteria identified with API Staph were 12 S. intermedius (33.3%), 2 S. aureus (5.6%), 1 S. haemolyticum (2.8%), and 1 S. xylosus (2.8%). Gram-negative organisms identified with API 20E or API NE included 8 Bordetella bronchiseptica (22.2%), 6 Escherichia coli (16.7%), 4 Pasteurella spp. (11.1%), 1 Enterobacter intermedius (2.8%), and 1 Oligella ureolytica (2.8%). Both Staphylococcus spp. isolates and Gram-negative pathogens were resistant to one or more antibiotics, including ampicillin (AM), amoxicillin/clavulanic acid (AMC), chloramphenicol (C), cefazolin (CZ), erythromycin (E), gentamicin (GM), kanamycin (K), lincomycin (L), oxacillin (OX), trimethoprim/sulfamethoxazole (SXT), and tetracycline (TE). All Staphylococcus spp. were susceptible to AMC, OX and VA, while many isolates were highly resistant to L (87.5%), E (68.8%), P (62.5%), and AM (56.3%). Antibiotic-resistant patterns of staphylococcal isolates were shown ranges from single to 9-resistant patterns. Resistant rates to antibiotics of Gram-negative bacteria were usually higher than those of Staphylococcus spp. in this study. Most Gram-negative bacteria were highly resistant to L (90.0%), AM (85.0%), E (85.0%), P (85.0%), OX (80.0%), and CZ (75.0%). B. bronchiseptica isolates showed 5 to 8 antibiotics-resistant patterns and Pasteurella spp., 2 to 8-resistant patterns. In particular, all 6 E. coli isolates were resistant to more than 9 different kinds of antibiotics, including one strain resistant to all antibiotics tested.

• Journal of Microbiology
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• 제44권3호
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• pp.336-343
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• 2006

We compared the antimicrobial resistance and clonal relationships among the community-acquired (CA) and hospital-acquired (HA) methicillin-resistant Staphylococcus aureus (MRSA) strains that were isolated from blood cultures in a university hospital over a 4-year period. A total of 131 MRSA isolates, including 28 CA-MRSA and 103 HA-MRSA strains, were identified; antimicrobial susceptibility testing indicated that the CA-MRSA isolates were more susceptible to erythromycin (21 % vs 6% ; P=0.02), clindamycin (46% vs 12%; P<0.01), ciprofloxacin (43% vs 11%; P<0.01), and gentamicin (43% vs 6%; P<0.01) than were the HA-MRSA isolates. Pulsed-field gel electrophoresis (PFGE) typing and antimicrobial resistance profiles separated the 20 CA-MRSA isolates into 14 and 10 different patterns, respectively, and the 53 HA-MRSA isolates were separated into 24 and 7 different patterns, respectively. Twenty-one (40%) of the 53 HA-MRSA isolates belonged to two predominant PFGE types, and most of them showed multi-drug resistant patterns. Four (20%) of the 20 CA-MRSA and 10 (19%) of the 53 HA-MRSA isolates fell into two common PFGE patterns, and each of them showed the same multi-drug resistant pattern. This study suggests that, although the CA-MRSA blood isolates showed diverse PFGE and antimicrobial resistance patterns, some of these isolates may have originated from the HA-MRSA strains.

• 대한수의학회지
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• 제28권1호
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• pp.83-87
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• 1988

The in vitro drug susceptibility of 83 strains of Bordetella bronchiseptica recovered from Korean pigs with atrophic rhinitis was investigated by the use of disk diffusion method. The majority of the organisms were highly resistant in order of prevalence to penicillin(98.7%), ampicillin(91.5%), streptomycin(90.3%), triple sulfa(83.1%), and trimethoprim/sulfamethoxazole(70.7%) while none of them were resistant to gentamicin, only 3.6% to colistin, chloramphenicol and kanamycin and 6.0% to tetracycline. The percentage of the organism resistant to bicozamycin, cephalothin and neomycin were 34.9%, 34.1% and 18.4%, respectively. A high prevalence of multiple drug resistance was observed and the 3 most common resistant patterns among 35 patterns noted were Am Pc Sm Sss Sxt(26.5%), Am Cf Pc Sm Sss Sxt(12.%) and Am Bm Pc Sm Sss Sxt(9.6%) patterns.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.199-206
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• 2008

Four hundred and thirteen oxytetracycline-resistant bacteria were recovered from six freshwater giant prawn farms with a history of oxytetracycline use. Most oxytetracycline-resistant isolates were Gram-negative bacteria. Six groups of oxytetracycline-resistant bacteria were classified using cluster analysis based on a comparison of levels of oxytetracycline resistance. Complex fingerprint patterns were obtained for 71 isolates studied. In general, the band patterns of isolates from different ponds were very similar, and the data indicated that the isolates were closely related. The exploration for cross-resistance found that most of the 71 oxytetracycline-resistant isolates were also resistant to tetracycline and chlortetracycline, but had a relatively low resistance to doxycycline. Many isolates showed higher chlortetracycline resistance than oxytetracycline resistance. Additionally, the oxytetracycline-resistant isolates were examined for the presence of tetracycline resistance (tet) genes. Fifty percent of the isolates carried one of the 14 known tet genes examined. The most common determinants were TetA and TetD. However, TetB, TetC, TetE, TetK, TetL, and TetM were also found with various frequencies.

• 한국동물위생학회지
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• 제40권2호
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• pp.83-87
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• 2017

59 strains of Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) were isolated from pigs in Gyeongbuk province, collected from 2011 to 2016. The isolates were investigated for the presence of antimicrobial resistance and multi drug resistance patterns. All 59 S. Typhimurium isolates were resistant to at least one of 10 antibiotics used in this study, 100% of S. Typhimurium isolates from pigs were resistant to two or more antimicrobials. As many as 5 isolates of isolates from pigs were resistant to 8 of 10 antimicrobials tested in this study. The ACSTNaGmKNaCf, ACSTGmAuKT/S, ACSTGmKCfT/S resistance phenotype was observed in 3.4%, 3.4%, 1.7% of the 59 isolates, respectively.

• Archives of Pharmacal Research
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• 제26권8호
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• pp.638-643
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• 2003

Raw milk samples, and cow and chicken intestines were tested to isolate vancomycin-resistant, gram-positive bacteria. From these samples, we isolated seven vancomycin-resistant Streptococcus equinus, two vancomycin-resistant viridans Streptococcus and two vancomycin-resistant Enterococcus faecium. The MICs of several antibiotics, including vancomycin, against these strains were tested. Seven isolates of S. equinus showed high level resistance to vancomycin and teicoplanin (＞100 $\mu$ g/mL). The cell wall thickness of these strains was compared with that of the sensitive strain by TEM and no differences were obserbed between these strains. We compared the strains of vancomycin-resistant Streptococcus equinus using PCR with Microbial Uniprimer Kit. We concluded that it is necessary to combine other methods in order to cluster and identify all isolates of S. equinus.

• 한국동물위생학회지
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• 제26권2호
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• pp.95-103
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• 2003

Isolates of 70 Proteus mirabilis were tested against 10 different antibiotics by a disc diffusion method as recommended by National Committee for Clinical Laboratory Standards (NCCLS). The isolates were resistant in order of tetracycline(100.0%), enrofloxacin(95.7%), ampicillin(74.3%), choramphenicol(62.9%), cephalothin(58.6%), streptomycin(50%), kanamycin(47.2%), neomycin(35.8%), gentamicin(15.7%), and amikacin(2.9%). In the antibiotic resistant patterns, 37 kinds of multiple resistance patterns of P mirabilis isolates were detected. The highest resistant pattern was ampicillin-cephalothin-chloramphenicol-enrofloxacin-tetracycline(11.6%).

• Tuberculosis and Respiratory Diseases
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• 제81권3호
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• pp.222-227
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• 2018

Background: Rifampicin (RFP) is one of the principal first-line drugs used in combination chemotherapies against Mycobacterium tuberculosis, and its use has greatly shortened the duration of chemotherapy for the successful treatment of drug-susceptible tuberculosis. Compensatory mutations have been identified in rpoC that restore the fitness of RFP-resistant M. tuberculosis strains with mutations in rpoB. To investigate rpoC mutation patterns, we analyzed 93 clinical M. tuberculosis isolates from patients in South Korea. Methods: Drug-resistant mycobacterial isolates were cultured to determine their susceptibility to anti-tubercular agents. Mutations in rpoC were identified by sequencing and compared with the relevant wild-type DNA sequence. Results: In total, 93 M. tuberculosis clinical isolates were successfully cultured and tested for drug susceptibilities. They included 75 drug-resistant tuberculosis species, of which 66 were RFP-resistant strains. rpoC mutations were found in 24 of the 66 RFP-resistant isolates (36.4%). Fifteen different types of mutations, including single mutations (22/24, 91.7%) and multiple mutations (2/24, 8.3%), were identified, and 12 of these mutations are reported for the first time in this study. The most frequent mutation involved a substitution at codon 452 (nt 1356) resulting in amino acid change F452L. Conclusion: Fifteen different types of mutations were identified and were predominantly single-nucleotide substitutions (91.7%). Mutations were found only in dual isoniazid- and RFP-resistant isolates of M. tuberculosis. No mutations were identified in any of the drug-susceptible strains.

• 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.