• Environmental Engineering Research
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• 제25권4호
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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.

• 한국동물위생학회지
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• 제36권2호
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• pp.73-78
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• 2013

This study was conducted to investigate antibiotic resistance among Salmonella Typhimurium isolates from diseased pigs in Gyeongbuk province during the period 1998~2011. One hundred forty one isolates were tested for antibiotic resistance using the standard disk diffusion method and were examined for presence of resistance gene by PCR method. S. Typhimurium showed high drug resistance rates to tetracycline (95.7%), streptomycin (93.6%), ampicillin (86.5%), cephalothin (80.1%), gentamicin (79.4%), and trimethoprim/sulfamethoxazole (72.3%). Resistance gene, blaTEM, blaPSE1, tetA, tetB, tetG, sul1, sul2, aadA, strA, grm, and temA were detected among the antibiotic resistance isolates and temB, tetC, aadB gene were not detected. One hundred twenty one (89.6%) tetA, two (1.5%) tetB and one (0.7%) tetG gene were detected in the 135 tetracycline resistant isolates. Two (1.6%) temA gene were detected in one hundred twenty two ampicillin resistance isolates and temB was not detected.

• 한국미생물·생명공학회지
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• 제51권3호
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• pp.268-279
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• 2023

The pharmaceutical industry in Bangladesh produces a diverse range of antibiotics for human and animal use, however, waste disposal management is inadequate. This results in substantial quantities of antibiotics being discharged into water bodies, which provide suitable environment for the growth of antibiotic-resistant bacteria, capable of spreading resistance genes. This study intended for exploring the bacterial antibiotic resistance profile in adjoining aquatic environmental sources of pharmaceutical manufacturing facilities in Bangladesh. Seven surface water samples were collected from the vicinity of two pharmaceutical industries located in the Savar area and 51 Escherichia coli isolates were identified using both phenotypic and genotypic methods. Antibiotic susceptibility tests revealed the highest percentage of resistance against ampicillin, azithromycin, and nalidixic acid (100%) and the lowest resistance against meropenem (1.96%) out of sixteen different antibiotics tested. 100% of the study E. coli isolates were observed with Multidrug resistance phenotypes, with the Multiple Antibiotic Resistance (MAR) value ranging from 0.6-1.0. Furthermore, 69% of the isolates were Extended Spectrum Beta-Lactamases (ESBL) positive as per the Double Disk Diffusion Synergy Test (DDST). ESBL resistance genes bla_TEM, bla_CTX-M-13, bla_CTX-M-15, and bla_SHV were detected in 70.6% (n = 36), 60.8% (n = 32), 54.9% (n = 28), and 1.96% (n = 1) of the isolates, respectively, by Polymerase Chain Reaction (PCR). Additionally, 15.68% (n = 8) of the isolates were positive for E. coli specific virulence genes in PCR. These findings suggest that pharmaceutical wastewater, if not properly treated, could be a formidable source of antibiotic resistance spread in the surrounding aquatic environment. Therefore, continued surveillance for drug resistance among bacterial populations around drug manufacturing facilities in Bangladesh is necessary, along with proper waste disposal management.

• 환경위생공학
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• 제22권4호
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• pp.55-63
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• 2007

We investigated the distribution and drug susceptibility test of V. vulnificus isolated from environmental sources in Incheon. In this survey, total 4,302 samples were obtained from different sites of the Incheon coastal area during the periods from march 2004 to November 2006. Among the 4,302 samples, 310 strains were isolated. The isolation rates of Vibrio vulnificus from fish, shellfish, estuarine water and sediment were 6.7%, 4.7%, 12.4% and 23.2%, respectively. The highest isolation rate was 14.6% in September and in spite of low temperature the isolation rate was 5.1% in November. The highest rate of antibiotic resistance was observed against streptomycin(15.3%), cefazolin(8.5%), cephalothin(8.3%), amikacin(8.3%), cefoxitin(6.7%) and nalidixic acid(6.7%). Seventeen percent of isolates were observed to be resistant to two or more of the antibiotics tested.

• 한국토양비료학회지
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• 제43권5호
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• pp.734-740
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• 2010

Overuse of veterinary antibiotics threats public health and surrounding environment due to the occurrence of antibiotic resistant bacteria. The objective of this study was to evaluate the antibiotic's concentrations of tetracycline (TC), chlortetracycline (CTC), and oxytetracycline (OTC) in a tetracycline group (TCs), sulfamethazine (SMT), sulfamethoxazole (SMX), and sulfathiazole (STZ) in a sulfonamide group, lasalocid (LSL), monensin (MNS), and salinomycin (SLM) in a ionophore (IPs), and tylosin (TYL) in a macrolide (MLs) group from soil, water, and sediment samples adjacent to a cattle manure composting facility. For all samples of soil, water, and sediment, the highest concentrations were detected in TCs among the tested antibiotics because of its higher annual consumption in veterinary farms, Korea and its higher cohesiveness with divalent or trivalent cations in soil. Moreover, the concentrations of residual antibiotics in September were generally higher than in June because of heavier rainfall in June. We suggest that continual monitoring and developing guideline of antibiotics are needed to control residual antibiotics in the environment.

• 한국동물위생학회지
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• 제23권1호
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• pp.77-91
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• 2000

This study was conducted to investigate the antibiotic resistance and plasmid profiles of 58 salmonella spp isolated from mesenteric lymphnodes of slaughter pigs in Kyoungbuk province during the period from September 1997 to June 1998. The results obtained are as follow that all isolates were susceptible to amikacin, gentamicin, ciprofloxacin and enrofloxacin, and the majority of isolates were highly susceptible to norfloxacin, colistin, nalidixic acid and apramycin while they were moderately susceptible to kanamycin, cephalothin, chloramphenicol, ampicillin, trimethoprim and penicillin. The majority of isolates were over 90% resistant rates to lincomycin, sulfadimethoxine, vancomycin, methicillin and erythromycin. The plasmid profiles of 58 salmonella spp are developed 1 to 4 fractions, 0.9 to 29.5 Kb molecular range sizes and U strains (45.5%) were showed plasmid profiles by agarose gel electrophoresis. 5 derby harbored 29.5 Kb and 7 Kb, and S schwarzengrund had 14 Kb and 0.9 Kb harboring sizes. Four of 10 S agona and 2 of 4 S typhimurium were harbored 3.1 Kb and n.5 Kb, respectively. Thirty-five untypable strains are developed variable size fractions its showed small size plasmid profile less than 6 Kb and 22 (62.8%) of them had no detectable plasmids.

• Journal of Periodontal and Implant Science
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• 제26권1호
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• pp.202-215
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• 1996

The purpose of this study was to an in estigate the antibiotic susceptibiliity of Actinoobacillus actinomycetemcomitans isolated from the subgingival plaque to adult periodontitis. Seven bacterial strains were tested for their susceptibility to 10 antimicrobial agents under disk diffusion method and broth dilution methold, Seven patients with deep pocket(6mm) were selected for this study. They had not taken antibiotics for 6 months and no history of dental treatment for 6 months and no history of dental treatment for 6 months before this study. The results were as follows : 1. For the antibiotic disk diffusion method, seven A. actinimycetemcomitans were tested with 10 antimicrobial agents which comprised penicillin, gentamycin, clindamycin, lincomycin, ampicillin, erythromycin, tetracycline, amikacin, chloramphenicol, and vancomycin. The sensitive antibiotics were tetracycline, vancomycin, and chloramphenicol and the resistant antibiotics were clindamycin, and lincomycin. The other antimicrobial agents were less active. 2. From the study of determination on the minimal inhibitory concentration(MIC) by broth dilution method, the MIC of tetracycline to seven strains of the A. actinomycetemcomitans was $0.5-1.0{\mu}g/ml$, that of clindamycin was $32{\mu}g/ml$. These data suggest that tetracycline may be valuable drugs in the elimination of A. actinimycetemcomitans from the patients with adult periodontitis

• 한국동물위생학회지
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• 제36권4호
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• pp.283-289
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• 2013

The antibiotic chemotherapy produces sometimes side effects and fails to eliminate bacterial infection. The occurrence of strains resistant to antibiotics would be expected to increase, and it is nowadays important to search for non-antibiotic substances. We are aimed to evaluate the effects of Torilis fructus extracts against enteropathogenic Escherichia coli (E. coli) in Piglets. The piglets were divided with three groups; Negative control group, E. coli-infected positive control group, and the Torilis fructus extracts treated group with E. coli infection. During the study period, we compared clinical signs, weight increase rate, fecal scores, gross findings between the treated group and non treated group. After necropsy, necropsy findings and histopathological findings were conducted with the comparison between the groups. As the results of this study, the Torilis fructus extracts additive showed the effects on the suppression of E. coli-induced lesions. On the basis of this study results, our data suggest that the Torilis fructus extracts additive have the antimicrobial effects. The Torilis fructus extracts additive could be used as the alternative material for antimicrobial feed additives.

• Journal of Periodontal and Implant Science
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• 제30권4호
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• pp.725-736
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• 2000

It is becoming increasingly apparent that periodontitis consists of mixture of diseases, most of which respond favorably to traditional mechanical therapy. Among these variants of the disease, some appear to be associated with unusual microbial infections and defective host defenses. Many of these fail to respond to conventional treatment. The recognition that some forms of periodontitis are refractory to standard periodontal therapy has given rise to a new classification of peridontitis. A series of 1692 subgingival microbial samples sent to a diagnostic microbiology laboratory included 738 samples that could be identified as compatible with a clinical diagnosis of refractory or recurrent periodontitis. In descending order of prevalence the associated microbiota included Bacteroides forsythus(85%) ,Fusobacterium species(78%), Spirochetes(67%), Campylobacter rectus(64%), Porphyromonas gingivalis(59%), Peptostreptococcus micros(58%), motile rods(46%), Prevotella intermedia(33%), Eikenella corrodens(13%), Capnocytophaga species(12%) ,and Actinobacillus actinomycetemcomitans(6%). Antibiotic resistance to tetracycline, penicillin G, or metronidazole was particularly noticeable for Fusobacterium species, Capnocytophaga species, and Actinobacillus actinomycetemcomitans. It was largely absent for Campylobacter rectus. No antibiotic data were obtained for Porphyromonas gingivalis or Bacteroides forsythus, as these species were detected by immunofluorescence. The results indicate that a substantial number of microorganisms associated with refractory periodontitis are variably resistant to commonly-used antibiotics. Diagnostic microbiology must be considered an essential adjunct to the therapist faced with periodontal lesions refractory to conventional treatment.

• Biomolecules & Therapeutics
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• 제31권2호
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• pp.141-147
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• 2023

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.