• Biomedical Science Letters
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• v.27 no.2
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• pp.59-68
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• 2021

Multidrug-resistant strain of Acinetobacter baumannii (MDRAB) is an emerging pathogen in health care facilities, preventing MDRAB is a public health concern. We conducted this experiment on a clinical isolate of A. baumannii with two main goals: the role of the efflux pump system in the stress provision of carbapenem and the response to the transcription level of the efflux pump gene. A total of 34 strains of A. baumannii was isolated from the Yangsan Hospital of Pusan National University. First, when we compared and observed the expression of the efflux pump gene and antibacterial resistance to carbapenem, a strong correlation was observed between carbapenem resistance and overexpression of adeB (P=0.0056). Second, a correlation between the efflux pump and concentration gradient and tolerance to carbapenem stress at the AdeABC efflux pump genes transcription level was confirmed. Our results revealed that the expression of the AdeABC efflux pump is an important resistance determinant in obtaining antibiotic resistance of the carbapenem group in A. baumannii.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.594-601
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• 2022

This study evaluated the biological properties of lemongrass (Cymbopogon citratus) extracts. The EtOAc extract of lemongrass had DPPH, TEAC, and nitric oxide-scavenging activity assay results of 58.06, 44.14, and 41.08% at the concentration of 50, 10, and 50 ㎍/ml, respectively. The EtOAc extract had higher elastase and collagenase inhibitory activities than the 80% MeOH, n-hexane, BuOH, and water extracts and comparable whitening activity toward monophenolase or diphenolase. Also, the EtOAc fraction had higher lipase inhibitory and antimicrobial activities against Cutibacterium acnes among extracts which is known to an important contributor to the progression of inflammatory acne vulgaris, and an opportunistic pathogen present in human skin. Total phenolic and flavonoid concentrations in the EtOAc extract were 132.31 mg CAE/g extract and 104.50 mg NE/g extract, respectively. Biologically active compounds in lemongrass extracts were analyzed by LC-MS. This study confirms that lemongrass extracts have potential use as cosmetic skincare ingredients. Thus, lemongrass can be considered a promising natural source of readily available, low-cost extracts rich in antioxidant, skincare, and antimicrobial compounds that might be suitable for replacing synthetic compounds in the cosmeceutical industry.

• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1003-1010
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• 2022

The purpose of this study was to examine the phytochemical compounds and antibacterial activity of Coffea robusta leaf extract (RLE). The results indicated that chlorogenic acid (CGA) is a major component of RLE. The minimum inhibitory concentrations (MICs) of RLE against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella Typhimurium were 6.25, 12.5, 12.5, and 12.5 mg/ml, respectively. RLE effectively damages the bacterial cell membrane integrity, as indicated by the high amounts of proteins and nucleic acids released from the bacteria, and disrupts bacterial cell membrane potential and permeability, as revealed via fluorescence analysis. Cytotoxicity testing showed that RLE is slightly toxic toward HepG2 cells at high concentration but exhibited no toxicity toward Caco2 cells. The results from the present study suggest that RLE has excellent potential applicability as an antimicrobial in the food industry.

• Pediatric Infection and Vaccine
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• v.30 no.3
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• pp.141-151
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• 2023

Purpose: Intestinal parasitic infections (IPIs) are a major health problem worldwide, especially in developing countries. According to the literature, children are more likely to get infected due to more frequent exposure to sources of infection. Methods: In this study, we collected 500 fecal samples from children under 15 years of age who referred to labs in Ilam city. All samples were microscopically examined using formalin-ether concentration and Trichrome staining techniques. The results were analyzed using SPSS 20.0. Results: Among 500 investigated samples, 4 types of parasites were detected. Giardia lamblia, Entameba coli, and Blastocystis hominis were identified as intestinal protozoa, and pinworm as intestinal worm. In this study, 23 cases (4.6%) had parasitic infections. 13 patients (2.6%) were infected with Giardia parasite, 4 patients (0.8%) with E. coli, 3 patients (0.6%) with B. hominis and 3 patients (0.6%) had pinworms. Conclusions: The findings of this study showed that the prevalence of IPIs among children aged under 15 years in Ilam is relatively down, which can be attributed of sufficient information of parents and children about the modes of parasite transmission and the important role of carriers in the pathogen cycle.

• Journal of Sericultural and Entomological Science
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• v.14 no.2
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• pp.81-92
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• 1972

Studies on Pathogenicity of Nosema bombycis Naegeli are summarized as follows: 1. The mortality of the parents, Jam 103 and Jam 104, is remarkbly higher than that of the hybrid, Jam 103$\times$Jam 104, whereas there is no difference in the mortality between the parents. 3. In the mortality of the pathogen-concentration, it is increased in order of the following concentrations inoculated, 10$^{8}$ , 10$^{7}$ , 10$^{8}$ and 10$^{5}$ /ml. 3. In the mortality of each instar, it is high in order of 5th, 4th, 3rd, and 2nd instar. 4. In the interaction between the mortalities of the varieties and the concentrations, 1) The mortality shows no differences between the parents and the hybrid in the high concentration of 10$^{8}$ /ml. 2) The mortality of the hybrid is lower than that of the parents in the low concentration of 10$^{5}$ /ml, whereas no difference is found between the parents. 3) The interaction appears at the same level in the middle concentration of 10$^{6}$ /ml to the parents and of 10$^{7}$ /ml to the hybrid. 5. It was pointed out that active immunity depends upon the volume of antigen injection, immunizing period, and injection intervals. In this experiment, it is noticed that the optimum volume of injection is above 20ml and D is the best one of the four treatment (A.B.C.D.). 6. The immune sera indicate such a 12,800 high titer in the indirect method can be obtained from the D immunizing method. Silkworm tissues and N. bombycis spores show self-fluorescence, but it is able to distinguish it from the F.I.T.C. by using the U.V. filter. 7. The midgut epithelium is examined to be the first site of the tissues which are penetrated into and multiplied by the inoculation of the pathogen per os.

• Journal of Korean Medicine Rehabilitation
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• v.25 no.2
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• pp.1-13
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• 2015

Objectives Methicillin-Resistant Staphylococcus aureus (MRSA) is a human pathogen and a major cause of hospital-acquired infections. New antibacterial agents that have not been compromised by bacterial resistance are needed to treat MRSA-related infections. In this study, we investigated the antimicrobial activity ofethanol extract of Haedokgeumhwa-san (HGH) which prescription is composed of korean medicine against MRSA. Methods The antibacterial activity of HGH extract was evaluated against MRSA strains by using the Disc diffusion method, broth microdilution method (minimal inhibitory concentration; MIC), checkerboard dilution test, and time-kill test; its mechanism of action was investigated by bacteriolysis, detergent or ATPase inhibitors. The checkerboard dilution test was used to examined synergistic effect of ampicillin, oxacillin, ciprofloxacin, vancomycin, gentamicin and norfloxacin in combination with HGH ethanol extract. A time-kill assay was performed a survival curve which was obtained by plotting viable colony counts depending on time on bacterial growth. Results The minimum inhibitory concentration (MIC) of ethanol extract (HGH) ranged from 1,000 to $2,000{\mu}g/mL$ against all the tested bacterial strains, respectively. We are able to confirm that HGH extract has potentially strong antibacterial activity. In the checkerboard dilution test, fractional inhibitory concentration index of HGH in combination with antibiotics indicated synergy or partial synergism against S. aureus. A time-kill study showed that the growth of the tested bacteria was considerably inhibited after 8 hr of treatment with the combination of HGH with selected antibiotics. For measurement of cell membrane permeability, HGH $250{\sim}1,000{\mu}g/mL$ along with concentration of Triton X-100 (TX) and Tris-(hydroxymethyl) aminomethane (Tris) were used. In the other hand, N,N-dicyclohexylcarbodimide (DCCD) and Sodium azide ($NaN_3$) was used as an inhibitor of ATPase. TX, Tris, DCCD and $NaN_3$ cooperation against S. aureus showed synergistic action. Accordingly, antimicrobial activity of HGH was affected by cell membrane and inhibitor of ATPase. Conclusions These results suggest that Haedokgeumhwa-san extract has antibacterial activity, and that HGH extract offers a potential as a natural antibiotic against MRSA.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.227-233
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• 2013

In this study, we evaluated the ability of various disinfectants to suppress the growth of microorganisms in fresh-cut products and organic vegetable. The growth of more than 50% of B. cereus isolates were suppressed by 50% ethanol, 0.1% hydrogen peroxide, 0.4% sodium hypochlorite or 1% calcium oxide. E. coli generally showed high susceptibility to concentration of 10% ethanol, 0.4% sodium hypochlorite and 1% calcium oxide. Eighty percent or more of S. aureus isolates exhibited resistance to ethanol, hydrogen peroxide and sodium hypochlorite, but the isolates were susceptible to concentrations of 1% calcium oxide. All isolates evaluated in this study were sensitive to benzalkonium chloride (BAC) and growth in the presence of $2.0{\mu}g/mL$ of BAC was completely inhibited. These pathogens showed widely different susceptibilities to different organic acids. Greater than 0.5% acetic acid and 2% and higher concentrations of malic acid and tartaric acid inhibited the growth of 60% of the isolates of B. cereus. Two percent acetic acid and tartaric acid inhibited 50% of the S. aureus isolates. Seventy percent of the E. coli isolates were resistant to malic acid and susceptible to 1% acetic acid and 10% tartaric acid. The antibacterial effects of the various sanitizers evaluated in this study were not only dependent on the type of disinfectant but also on the pathogen. Thus, it is important to select a sanitizer that is safe and effective at removing specific types of microorganisms.

• Journal of Korean Foot and Ankle Society
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• v.13 no.2
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• pp.150-155
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• 2009

Purpose: To help the empirical antibiotics selection in diabetic foot infection patients, we investigated prevalence of microorganisms and their antibiotics sensitivity results. Materials and Methods: Patients who came to our clinics to treat diabetic foot infections with deep ulceration and were followed up more than 6 months until complete recovery were adopted. From March 2006 to June 2009, there were 140 patients who corresponded with such a inclusion criteria. Wound cultures were done by deep tissue or bone debris at first visit to our clinics. Microorganisms which was documented by wound culture and most susceptible antibiotics by minimum inhibitory concentrations were surveyed retrospectively. Results: Microorganisms were confirmed in 113 cases (80.7%). In the other 27 cases (19.3%), there were no cultured microorganisms. In bacterial growth group, there were 72 cases (63.7%) of gram-positive bacteria and 41 cases (36.3%) of gram-negative bacteria. All of them were aerobic microorganisms and there were no anaerobic microorganisms. Methicillin-sensitive staphylococcus aureus was the most common pathogen and accounted for 35 cases (31.0%). As other common pathogens, there were Enterobacter cloacae (11 cases, 9.7%), pseudomonas aeruginosa (10 cases, 8.8%), Methicillin-resistant staphylococcus aureus (10 cases, 8.8%) and enterococcus faecalis (6 cases, 5.3%), and so on. Common susceptible antibiotics in gram positive microorganism were vancomycin (60 cases, 83.3%), teicoplanin (60 cases, 83.3%), nitrofurantoin (60 cases, 83.3%) and ciprofloxacin (53 cases, 73.6%). In gram negative ones, common susceptible antibiotics were imipenem (35 cases, 85.3%), piperacillin/tazobactam (33 cases, 80.5%) and gentamicin (31 cases, 75.6%). Conclusion: Methicillin-sensitive Staphylococcus aureus in gram positive and enterobacter cloacae in gram negative was the most common pathogen in each group. Ciprofloxacin and gentamicin might be adaptable as a first-line empirical antibiotics in infected diabetic foot patients.

• Journal of Mushroom
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• v.13 no.2
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• pp.97-102
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• 2015

This study was conducted to investigate optimum conditions for mass production of antagonistic microbes Pseudomonas azotoformans HC5. P. azotoformans HC5 is a potent biological control agent to control brown blotch disease caused by Pseudomonas tolaasii. This markedly showed the antagonistic activity against P. tolaasii, the most destructive pathogen of cultivated mushrooms. To define the optimum conditions for the mass production of the P. azotoformans HC5, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 6.0 and $15^{\circ}C$, respectively. The optimal concentration of medium elements for the growth of pathogen inhibitor bacterium was determined as follows: 0.6% adonitol, 1.5% yeast extract, 0.8% $NH_4H_2PO_4$, 5mM $MgSO_4$, and 0.2% asparagine.

• Journal of Mushroom
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• v.14 no.4
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• pp.191-196
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• 2016

This study was conducted to investigate optimum conditions for mass production of ntagonistic microbes Alcaligenes sp. HC12. Alcaligenes sp. HC12 had a potent biological control agent to control browning disease caused by Pseudomonas agarici. Alcaligenes sp. HC12 markedly showed the antagonistic activity against Pseudomonas agarici, the most destructive pathogen of cultivated mushrooms. To define the optimum conditions for the mass production of the Alcaligenes sp. HC12, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 9.0 and $30^{\circ}$, respectively. The optimal concentration of medium elements for the growth of pathogen inhibitor bacterium(Alcaligenes sp. HC12) was determined as follows: 0.5% dextrine, 1.5% yest extract, 1.0% $NaNO_3$, 0.5% $KH_2PO_4$, and 1.5% asparagine.