• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.79-84
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• 2013

In an effort to discover an alternative antibiotic for treating infections with methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas sp. UJ-6, a marine bacterium that exhibited antibacterial activity against MRSA, was isolated. The culture broth and its ethyl acetate extract exhibited bactericidal activity against MRSA. The extract also exhibited antibacterial activity against gram-negative bacteria, which were not susceptible to vancomycin. The treatment of MRSA with the extract resulted in abnormal cell lysis. The extract retained >95% of its anti-MRSA activity after heat treatment for 15 min at $121^{\circ}C$. Thus, although most antibiotics are unstable under conditions of thermal stress, Pseudomonas sp. UJ-6 produces a heat-stable anti-MRSA substance. The results of this study strongly suggest that Pseudomonas sp. UJ-6 can be used to develop a novel, heat-stable, broad-spectrum antibiotic for the treatment of MRSA infections.

• Korean Journal of Veterinary Research
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• v.30 no.4
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• pp.427-434
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• 1990

The purpose of this study was to examine O serotypes, colicin and hemolysin production. antibiotic susceptibility and haemagglutinating ability to animal erythrocytes among Escherichia coli strains isolated from pigeons in Taegu province. Of the 166 strains isolated, 28 strains (16.9%) were classified into 6 O serotypes and their types were O20(42.9%), O15(17.9%), O139(14.3%), O101(10.7%), O149(7.1%) and O8(7.1%). Of the 166 strains isolated, none was hemolytic and 3(1.8%) were colicinogenic. Antibiotic susceptibility test of Escherichia coli isolates was performed by the agar dilution method, using ampicillin, chloramphnicol, gentamicin, rifampicin, streptomycin (Sm), nalidixic acid, sulfadimethoxine and tetracycline (Tc). Forty four strains (26.5%) were resistant to one or more drugs and the most common resistance patterns were SmTc (27.3%). Of the 44 drug resistant strains, 6 strains haemagglutinated erythrocytes of chicken, guinea pig and 2 of the 6 strains agglutinated goose erythrocytes.

• Korean Journal of Veterinary Research
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• v.23 no.2
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• pp.173-178
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• 1983

This paper deals with the isolation of citrate-utilizing variants of Escherichia coli ($Cit^+$ E. coli) from the animals, their biochemical reactivity and antibiotic susceptibility, and whether the citrate utilizing ability is transmissible. One hundred arid twenty-three isolates of $Cit^+$ E. coli were obtained from cattle and pigs. but from other animals, no isolates were obtaied. Antibiotic susceptibility testing of $Cit^+$ E. coli was performed by the agar dilution method, using the following 9 antibiotics, chloramphenicol(CP), tetracycline(TC), streptomycine(SM), kanamycin(KM), colistin(CL), gentamicin(GM), cephaloridine(CR), aminobenzycillin and nalidixic acid(NA). All the variants tested were susceptible to KM, CL, GM, CR and NA. Of all the variants, 80(65%) were resistant to the drugs tested and resistance to TC and SM was most frequent. The transmission of the ability to utilize citrate on Simmons citrate agar at $37^{\circ}C$ was demonstrated in 78(67.8%) out of the 115 $Cit^+$ E. coli. There were no significant difference in the transfer rates of citrate utilizing ability between resistant and susceptible variants to above 9 drugs. Of 123 isolates, 8 were lost their citrate utilizing ability, spontaneously.

• Journal of Microbiology
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• v.45 no.1
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• pp.6-10
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• 2007

Culture broth of a streptomycete isolate, Streptomyces sp. CS684 showed antibacterial activity on methicilin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE). Among purified substances from the organism, CSU-1, which is active against MRSA and VRE, is a $C_{37}H_{62}O_{12}Na\;(M^+,721.3875)$, and identified as laidlomycin. The anti-MRSA and anti-VRE activity of CSU-1 was stronger than oxacillin and vancomycin. Phylogenetic analysis showed that strain CS684 is very similar to Streptomyces ardus NRRL $2817^T$, whereas the ability of Streptomyces sp. CS684 to produce laidlomycin was shown to be unique.

• Korean Journal of Clinical Laboratory Science
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• v.36 no.2
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• pp.89-97
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• 2004

Many strains of Staphylococcus aureus were isolated from pus samples from primary, secondary, and tertiary medical institutions and were subjected to an antibiotic sensitivity test. Ciprofloxacin, clindamycin, erythromycin, gentamicin, oxacillin penicillin, tetracycline, trimethoprim/sulfamethoxazole, vancomycin and teicoplanin were used for the antibiotic sensitivity test. The strains showed hightest resistance to penicillin(91%), but all of strains tested were susceptible to vancomycin and teicoplanin. The isolated multi-drug(penicillin-tetracycline-ciprofloxacin-clindamycin-erythromycin- oxacillin-gentamicin) resistant S. aureus were analyzed genotypically using an AP-PCR(Arbitrarily Primed polymerase chain reaction) with an arbitrary 3 primers. Based on the result for genotype analysis, the genotypes identified by S1 primer did not coincide with those of S2 or E2 primers. Genotypes identified by S2 primer did not coincide with those of S1 or E2 primers. Also genotypes identified by the E2 primer did not coincide with those of S1 or S2 primers. Therefore, an analysis of AP-PCR test with multiple primers will provide more sensitive identification. A strain from a secondary medical institution and a strain from a tertiary medical institution which showed the same genotype for S1, S2, and E2 primers are required for further epidemiological study.

• Fisheries and Aquatic Sciences
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• v.12 no.1
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• pp.24-28
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• 2009

A tetracycline resistant Vibrio parahaemolyticus, capable of growing on TCBS medium containing tetracycline, was isolated from cultivated fishes. A gene responsible for the tetracycline resistance was cloned from chromosomal DNA of the V. parahaemolyticus strain using Escherichia coli KAM3, which lacks major multi-drug efflux pumps (${\Delta}acrB$) as host cells. The nucleotide sequence and homology analysis revealed an open reading frame (ORF) for tetracycline resistance protein (TetB). In order to characterize the antibiotic resistance of TetB originated from the V. parahaemolyticus strain, the gene was sub cloned into plasmid pSTV28. The resulting plasmid was designated as pSTVTetB and transformated into E. coli KAM3. E. coli KAM3 cells harboring the recombinant plasmid pSTVTetB are able to grow on plates containing tetracycline and oxytetracycline but not doxycycline, indicating that the tetB gene confers the tetracycline- and oxytetracycline-resistance to the host cell.

• Korean Journal of Poultry Science
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• v.38 no.2
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• pp.155-164
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• 2011

The use of antimicrobials will be soon removed due to an increase of occurrence of antibiotic-resistant bacteria or ionophore-resistant Eimeria species in poultry farms and consumers' preference on drug-free chicken meats or eggs. Although dietary antimicrobials contributed to the growth and health of the chickens, we do not fully understand their interrelationship among antimicrobials, gut microbiota, and host immunity in poultry. In this review, we explored the current understanding on the effects of antimicrobials on gut microbiota and immune systems of chickens. Based on the published literatures, it is clear that antibiotics and antibiotic ionophores, when used singly or in combination could influence gut microbiota. However, antimicrobial effect on gut microbiota varied depending on the samples (e.g., gut locations, digesta vs. mucosa) used and among the experiments. It was noted that the digesta vs. the mucosa is the preferred sample with the results of no change, increase, or decrease in gut microbiota community. In future, the mucosa-associated bacteria should be targeted as they are known to closely interact with the host immune system and pathogen control. Although limited, dietary antimicrobials are known to modulate humoral and cell-mediated immunities. Ironically, the evidence is increasing that dietary antimicrobials may play an important role in triggering enteric disease such as gangrenous dermatitis, a devastating disease in poultry industry. Future work should be done to unravel our understanding on the complex interaction of host-pathogen-microbiota-antimicrobials in poultry.

• Korean Journal of Veterinary Research
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• v.32 no.1
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• pp.63-76
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• 1992

A study on the isolation of Yersinia from the feces of healthy pigs and the biotype and serotype and susceptibility to 16 antimicrobials was carried. Out of 853 pigs, Yersiniae were isolated from 349 pigs(40.9%). Of 349 isolates, 289 isolates(82.8%) were Yersinia enterocolitica and 54(15.5%) were Y kristensenii, 3(0.9%) were Y pesudotuberculosis and the rest 3(0.9%) were Y prederiksenii. Out of 289 isolates of Y enterocolitica, the predominants biotype was 3B comprising of 165 isolates(57.1%) and followed by biotype 2, comprising of 49 isolates(17.0%), bioptype 3A, comprising of 41 isolates(14.2%) and biotype 4 comprising of 23 isolates(8.0%). And the predominant serotype was 0 : 3 comprising of 231 isolates(79.9%) and followed by serotype 0 : 9 comprising of 42 isolates(14.5%) and 0 : 21 comprising of 10 isolates(3.5%). Y. enterocolitica were resistant to cephalothin(99%), novobiocin(99%), erythromycine(83%), ampicillin(83%) and carbenicillin(81%) and susceptible to amikacin(100%), colistin(100%), gentamicin(100%), kanamycin(100%), polymyxin B(100%), tobramycin(100%), chloramphenicol(99%), nalidixic acid(99%), neomycin(99%), streptomycin(99%) and tetracycline(99%). Most strains of biotype 2/serotype 0 : 9 were susceptible to carbenicillin(100%) and ampicillin(61%) but the other biotype/serotypes were resistant to these antibiotic.

• Korean Journal of Microbiology
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• v.23 no.4
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• pp.282-290
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• 1985

Small size antibiotic resistance plasmids having molecular weights less than 10 Mdal were isolated and characterized from ten clinically isolated multiple resistant Staphylococcus aureus. Agarose gel electrophoresis profiles and antibiotic resistance patterns divided these strains into four groups. Strain 2-23-6, the representative strain of a group of five strains conferred two plasmids of molecular weights $1.6{\times}10^6\;dal\;and\;2.0{\times}10^6$ dal. The small plasmid (pSBK 112) specified macrolides, lincosamides and streptogramin type B (MLS) resistance gene which are expressed constitutively. Lage plasmid (pSBK 125) specified chloramphenicol resistance gene which is inducible. Strain 10-5 conferred a $3.0{\times}10^6$ dal plasmid (pSBK 141) which carry an inducible ampicillin resistance gene and strain P-H-2 conferred and $1.6{\times}10^6$ dal plasmid (pSBK 190) which carry a constitutive MLS resistance gene. Strain D-H-1 conferred four plasmids of molecular weights $0.8{\times}10^6$ dal (pSBK 201), $1.6{\times}10^6$ dal (pSBK 202), $2.5{\times}10^6$ dal (pSBK 203), and $1.2{\times}10^7$ dal (pDBK 204), respectively. Among those four plasmids, only pSBK 203 specified chloramphenicol resistance gene. Curing of constitutive MLS resistance using acriding orange or ethidium bromide in 2-23-6 and P-H-2 strains produced 'inducible' MLS resistance strains which are less resistant to MLS than the wild type strains, suggesting that there are two resistance genes in both strains; one is constitutive and the other is inducible.

• Clinical and Experimental Pediatrics
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• v.64 no.8
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• pp.415-421
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• 2021

Background: Antibiotic resistance is associated with longer hospitalizations, higher treatment costs, and increased morbidity and mortality rates. Purpose: This study aimed to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Iranian children. Methods: International databases, including Web of Science, PubMed, Embase, and Scopus, and Iranian databases, including Scientific Information Database (www.sid.ir), Magiran, and Iranian Database for Medical Literature (idml.research.ac.ir), were systematically searched for articles published between January 2000 and August 2019. Sources of heterogeneity were determined using subgroup analysis and meta-regression. Results: Overall, 343 studies were identified; of them, 20 were included in the meta-analysis to estimate the pooled prevalence. The pooled prevalence of MRSA was 42% (95% confidence interval [CI], 29-55) among culture-positive cases of S. aureus, 51% (95% CI, 39-62) in hospitalized children, and 14% (95% CI, 0.05-27) in healthy children. Conclusion: The overall pooled prevalence of MRSA in children was 42%. Appropriate infection control measures and effective antibiotic therapy are needed.