Research Note: Study on the antibacterial activity of Chinese herbal medicine against Aspergillus flavus and Aspergillus fumigatus of duck origin in laying hens.

Aspergillus flavus and Aspergillus fumigatus were derived and identified from the ducks infected with fungi. In order to investigate the effectiveness of Chinese herbal medicines against Aspergillus flavus and Aspergillus fumigatus, in vitro antibacterial test and animal infection control test were conducted to study the antibacterial activity of the Chinese medicine mixture which was compatible with Acorus gramineus, Phellodendron chinensis, and Cassia obtusifolia. According to the results, the liver of chickens infected with Aspergillus flavus and Aspergillus fumigatus displayed granulomatous lesions, indicating that the isolation of pathogen from the lungs of sick ducks is also pathogenic to chickens. As suggested by the results of in vitro drug sensitivity test, the mixture 1 MIC80 was the minimum, the MIC80 of Aspergillus flavus was 16 µg/µL, and the MIC80 of Aspergillus fumigatus was 4 µg/µL. In a petri dish of the same concentration, the colony diameter of Aspergillus flavus and Aspergillus fumigatus in Mixture 1 was the minimum. Besides, Aspergillus flavus colonies grew when the concentration was 64 µg/µL, and Aspergillus fumigatus colonies grew when the concentration was 4 µg/µL, which suggests the more significant inhibitory effect of Mixture 1 on Aspergillus flavus and Aspergillus fumigatus. According to the results of animal experiments, there was a significantly lower activity level of Glutamic oxaloacetic transaminase (GOT) and Glutamate pyruvic transaminase (GPT) in the protection group and the treatment group than in the bacterial infection group. As indicated by the blood smear results, there were more neutrophils in the infected group than in the prevention group and the treatment group. Thus, it can be seen from that the Mixture 1 produced preventive and therapeutic effects on the chickens infected with Aspergillus flavus and Aspergillus fumigatus.

Antifungal Effects of New Synthetic Materials, KAF-200522 and KAF-200522-HCl, on in vitro and in vivo Models / 한국실험동물학회지

KAF-200522 and its chloride form, KAF-200522-HCl, were invented in Chemon inc. as new triazole antifungal agents with excellent activities in vivo and in vitro against wide range of fungi. As a result of in vitro susceptibility measurements, 80% minimum inhibitory concentrations (MIC80) of both test articles against Candida albican sp. and Aspergillus fumigatus sp. were below 0.0156 microg/mL, which were over 4,100 times lower than those of fluconazole against fluconazole resistant C. albican sp. and A. fumigatus sp., and were over 16 times lower than those of amphotericin B against above same fungi. Additionally, against representative dermatophytes, Trichophyton sp., the MIC80s of both test articles were below 0.0156 microg/mL which were over 64 times lower than those of fluconazole and amphotericin B. As in vivo antifungal activities in A. fumigatus sp. infected mouse models, KAF-200522 treatment group at 600 mg/kg showed 80% survival rate which was 2 times higher than that of amphotericin B and showed 13.7 days in the mean survival time (MST) which was about 2.1 times higher than that of amphotericin B. But in KAF-200522-HCl treatment groups, all animals were found dead in contrast to 40% survival rate in amphotericin B treatment group, however dose dependent increases in MST was revealed. In conclusion, antifungal activities of KAF-200522 and its mimics, KAF-200522-HCl in vitro and in vivo were confirmed in this study, therefore the potentiality of the present compounds to be developed into new antifungal drug was expected.

Why do antimicrobial agents become ineffectual?

Antibiotic resistance has evolved over the past 50 years from a merely microbiological curiosity to a serious medical problem in hospitals all over the world. Resistance has been reported in almost all species of gram-positive and -negative bacteria to various classes of antibiotics including recently developed ones. Bacteria acquire resistance by reducing permeability and intracellular accumulation, by alteration of targets of antibiotic action, and by enzymatic modification of antibiotics. Inappropriate use of an antibiotic selects resistant strains much more frequently. Once resistant bacteria has emerged, the resistance can be transferred to other bacteria by various mechanisms, resulting in multiresistant strains. MRSA is one of the typical multiresistant nosocomial pathogens. A study of the PFGE pattern of endonuclease-digested chromosomal DNA showed that MRSA of a few clones were disseminated among newborns in the NICU of a Japanese hospital. In this regard, it is important to choose appropriate antibiotics and then after some time, to change to other classes to reduce the selection of resistant strains. Since the development of epoch-making new antibiotics is not expected in the near future, it has become very important to use existing antibiotics prudently based on mechanisms of antibiotic action and bacterial resistance. Control of nosocomial infection is also very important to reduce further spread of resistant bacteria.