• Clinical and Experimental Pediatrics
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• v.55 no.2
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• pp.42-47
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• 2012

$Mycoplasma$ $pneumoniae$ (MP), the smallest self-replicating biological system, is a common cause of upper and lower respiratory tract infections, leading to a wide range of pulmonary and extra-pulmonary manifestations. MP pneumonia has been reported in 10 to 40% of cases of community-acquired pneumonia and shows an even higher proportion during epidemics. MP infection is endemic in larger communities of the world with cyclic epidemics every 3 to 7 years. In Korea, 3 to 4-year cycles have been observed from the mid-1980s to present. Although a variety of serologic assays and polymerase chain reaction (PCR) techniques are available for the diagnosis of MP infections, early diagnosis of MP pneumonia is limited by the lack of immunoglobulin (Ig) M antibodies and variable PCR results in the early stages of the infection. Thus, short-term paired IgM serologic tests may be mandatory for an early and definitive diagnosis. MP infection is usually a mild and self-limiting disease without specific treatment, and if needed, macrolides are generally used as a first-choice drug for children. Recently, macrolide-resistant MP strains have been reported worldwide. However, there are few reports of apparent treatment failure, such as progression of pneumonia to acute respiratory distress syndrome despite macrolide treatment. The immunopathogenesis of MP pneumonia is believed to be a hyperimmune reaction of the host to the insults from MP infection, including cytokine overproduction and immune cell activation (T cells). In this context, immunomodulatory treatment (corticosteroids or/and intravenous Ig), in addition to antibiotic treatment, might be considered for patients with severe infection.

• Journal of Life Science
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• v.14 no.2
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• pp.225-228
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• 2004

Natamycin, produced by Streptomyces natalensis ATCC27448, is a polyene macrolide antibiotic, is widely used in the food industry in order to prevent mould contamination. This study carried out to develop an efficient purification process of natamycin from fermentation broth. The stability of natamycin in fermentation broth during storage period was investigated at 4$^{\circ}C$ and room temperature. After the storage of fermentation broth for 14 days at 4$^{\circ}C$, residual activity of natamycin was about 80% but decreased by 27% at room temperature. As solvent to extract natamycin from fermentation broth, methanol was the most efficient. A developed purification procedure includes methanol extraction and Diaion HP-20 column chromatography. Approximately 2.9 g of natamycin was obtained with a final yield of 69.1% and purity of 96.6% from 1.8 l of fermentation broth by this developed purification procedure.

• Pediatric Infection and Vaccine
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• v.9 no.2
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• pp.175-181
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• 2002

Purpose : Scrub typhus(tsutsugamushi disease) is a febrile disease characterized by fever, rash, eschar, lymphadenopathy. Therapy with tetracycline(doxycycline) or chloramphenicol is currently recommended for the treatment for scrub typhus. But there are limitations in usage a tetracycline(doxycycline) for scrub typhus in the children. Recently, there was a report that azithromycin, a macrolide antibiotic was used for scrub typhus in pregnant woman successfully. So we evaluated the effectiveness of the Clarithromycin, other a macrolide antibiotic, for scrub typhus. Methods : Seven patients with scrub typhus at department of internal medicine and three patients with scrub typhus at department of pediatrics Masan Fatima Hospital were involved for this study. A serologic diagnosis for scrub typhus were performed by use of passive hemagglutination test. Clarithromycin(Abbott Laboratories, North Chicago, IL, USA) was administrated orally in a daily dose of 500 mg for adult patients and 15 mg/kg/bid/day for pediatric patients. Results : There were 7 cases of adult patients, varying from 28 to 76 years of age and 3 cases of pediatirc patients, varying from 4 to 7 years of age with scrub typhus. All of cases had fever, myalgia, headache, rash, eschar. Seven cases had positive passive hemagglutination test and eight cases had abnormal liver function. Mean duration for the removal of fever after medication was 1.3 day(1~2 days) and all cases were recovered without complications. Conclusion : Our results suggest that Clarithromycin therapy may be effective for scrub typhus.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.200-208
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• 2011

Most problematic antibiotic resistance mechanism for MLS (macrolide-lincosamide-streptogramn B) antibiotics encountered in clinical practice is mono- or dimethylation of specific adenine residue at 2058 (E. coli coordinate) of 23S rRNA which is performed by Erm (erythromycin ribosome resistance) protein through which bacterial ribosomes reduce the affinity to the antibiotics and become resistant to them. ErmSF is one of the four gene products produced by Streptomyces fradiae to be resistant to its own antibiotic, tylosin. Unlike other Erm proteins, ErmSF harbors idiosyncratic long N-terminal end region (NTER) 25% of which is comprised of arginine well known to interact with RNA. Furthermore, NTER was found to be important because when it was truncated, most of the enzyme activity was lost. Based on these facts, capability of NTER peptide to inhibit the enzymatic activity of ErmSF was sought. For this, expression system for two different proteins to be expressed in one cell was developed. In this system, two plasmids, pET23b and pACYC184 have unique replication origins to be compatible with each other in a cell. And expression system harboring promoter, ribosome binding site and transcription termination signal is identical but disparate amount of protein could be expressed according to the copy number of each vector, 15 for pACYC and 40 for pET23b. Expression of NTER peptide in pET23b together with ErmSF in pACYC 184 in E. coli successfully gave more amounts of NTER than ErmSF but no inhibitory effects were observed suggesting that there should be dynamicity in interaction between ErmSF and rRNA rather than simple and fixed binding to each other in methylation of 23S rRNA by ErmSF.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.258-265
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• 2009

A study on livestock environment improving agents was conducted; top two brands (A and B) in the market, bottom two brands (E and F) based on market shares and two newly developed agents (C and D) were measured for viable count and tested for resistance towards antibiotics prohibited against livestock feeds. Test results revealed that the measured viable count of agents A and B matched those on the labels were identical; however agent E lacked information on viable counts nor the intended usage, while the measured viable count of agent F was less than the label-stated count. No correlation was found between the antibiotic-resistance test and market share, and most of the agents excluding B were found to display resistance case of Lincosimides such as Lincomycine and Clindmycin, resistant bacteria were found, with the except of agent B. Amoxicillin, Ampicillin and Penillin (type-Penecillins) and Erythromycin (type-Macrolide) were shown to contain resistant bacteria, with the except of agents Band E; the same for Norploxacin (type-Quinoline) and Neomycin antibiotics. Aminoglycosides such as Gentamycin and Streptomycin contained resistant bacteria, excluding agent B. Oxytetracyclin (type-Tetracycline), which is banned for use as resistant bacteria showed the highest sensitivity among the 12 antibiotics, revealed positive results in the test for resistant bacteria; again excluding of agents Band E. These results reveal that many agents contained resistant bacteria despite the fact that they were prohibited; this calls for a more accurate display of the facts and specifications, systematic distributions and strict verification processes of environment improving agents.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.105-111
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• 2013

The Erm family of adenine-$N^6$ methyltransferases (MTases) is responsible for the development of resistance to macrolide-lincosamide-streptogramin B antibiotics through the methylation of 23S ribosomal RNA. Recently, it has been proposed that well conserved amino acids in ErnC' located in concave cleft between N-terminal 'catalytic' domain and C-terminal 'RNA-binding' domain interacts with substrate RNA. We carried out the site-directed mutagenesis and studied the function of the ErmSF R237 mutant in vitro and in vivo. R237 amino acid residue is located in the concave cleft between two domains. Furthermore this residue is very highly conserved in almost all the Erm family. Purified mutant protein exhibited only 51% enzyme activity compared to wild-type. Escherichia coli with R237A mutant protein compared to the wild-type protein expressing E. coli did not show any difference in its MIC (minimal inhibitory concentration) suggesting that even with lowered enzyme activity, mutant protein was able to efficiently methylate 23S rRNA to confer the resistance on E. coli expressing this protein. But this observation strongly suggests that R237 of ErmSF probably interacts with substrate RNA affecting enzyme activity significantly.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.180-186
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• 2007

The biocontrol agent, Serratia plymuthica A21-4, has been developed for controlling pepper Phytophthora blight. Serratia plymuthica A21-4 strongly inhibits the mycelial growth, zoospore formation, and cyst germination of Phytophthora capsici in vitro. The application of a cell suspension of strain A21-4 to pepper plants in pot experiments and in greenhouse successfully controlled the disease. The bacteria produced a potent antifungal substance which was a key factor in the suppression of Phytophthora capsici. The most active chemical com-pound was isolated and purified by antifungal activity-guided fractionation. The chemical structure was identified as a chlorinated macrolide $(C_{23}H_{31}O_8Cl)$ by spectroscopic (UV, IR, MS, and NMR) data, and was named macrocyclic lactone A21-4. The active compound significantly inhibited the formation of zoosporangia and zoospore and germination of cyst of P. capsici at concentrations lower than $0.0625{\mu}g/ml$. The effective concentrations of the macrocyclic lactone A21-4 for $ED_{50}$ of mycelial growth inhibition were $0.25{\mu}g/ml,\;0.25{\mu}g/ml,\;0.30{\mu}g/ml \;and\;0.75{\mu}g/ml$ against P. capsici, Pythium ultimum, Sclerotinia sclerotiorum and Botrytis cinerea, respectively.

• Korean Journal of Veterinary Service
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• v.22 no.1
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• pp.93-101
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• 1999

This test process on screening method for the detection of residual antibiotics in milk is simple, economic, sensitive to residual antibiotics and was given approval international organs. Thus, this study was carried out the comparison of Disk assay method and TTC-II method for sensitivity and minimum detectable range of antibiotics in raw milk. The results of this study was summarized as follows ; 1. The number of samples requested for treatment of mastitis was 198 samples. Comparison or analytical results among the methods of TTC-II, disk assay and Delve sp was that TTC-II 37 samples(18.6% ), Disk assay 125samples(63.1%), Delve SP 130 samples(65.7% ) reacted positively. Conformity rate of Delve SP and Disk assay was 70%. 2. Detectable limits of disk assay method in some antibiotics were more sensitive than those of official method(0.05-0.0025ppm in the $\beta$-lactams, 1ppm in two aminoglycoside, 0.2 ppm in one tetracycline, similar in one macrolide) 3. For sensitivity of residual sulfonamides TTC-II was much more sensitive than disk assay. Detectable limits of sulfamethazine and sulfadimethoxine were 30 to 50ppm levels. 4. The best medium preservation period is 1-2 days. 5. Concentration of brome cresol purple related to resistance for B stearothermophilus culture was 24ppm/ml. These results show that disk assay method for screening detection of antibiotics residuces in milk is worthy of use.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.449-457
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• 2021

The aim of the present study was to survey the frequency of inducible and constitutive phenotypes and inducible cross-resistant genes by regulating the methylation of 23S rRNA (ermA, ermB, and ermC) and macrolide efflux-related msrA gene in Staphylococcus aureus and S. epidermidis strains. A total of 172 bacterial isolates (identified based on standard tests), were examined in this study. Antibiotic susceptibility was determined by the disk diffusion method, and all isolates were evaluated with respect to inducible and constitutive phenotypes. The presence of ermA, ermB, ermC, and msrA genes was investigated by a PCR assay. The constitutive resistance phenotypes showed a higher distribution among the isolates. R phenotype was detected more among S. epidermidis isolates (46.25%). ermB, ermC, and msrA genes were detected more in methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) isolates that had R and HD phenotypes (>77% strains). The ermA gene had the lowest frequency among MRSA, MRSE, MSSA, and MSSE strains (<14% isolates). Distribution of inducible resistance genes in MRSA and MRSE strains, and possibly other species, leads to increased constitutive resistance to erythromycin, clindamycin, and other similar antibiotics. Therefore, it can be challenging to treat infections caused by these resistant strains.

• Journal of Yeungnam Medical Science
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• v.29 no.2
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• pp.89-95
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• 2012

Background: As Mycoplasma pneumoniae pneumonia has increased in Korea, its relevance to infants, toddlers, and adolescents has magnified as well as. However, it is difficult to perform the serological test and PCR test routinely for diagnosis in actual clinical practice. Thus, the authors conducted this study to help clinicians do presumptive diagnosis of Mycoplasma pneumoniae pneumonia using clinical, radiological, and hematological findings. Methods: The study population consisted of 224 children between 1 month and 14 years old, hospitalized for radiographically confirmed pneumonia. Patients were divided into two groups of 100 children with Mycoplasma pneumoniae pneumonia, as diagnosed using the ELISA method. Groups with negative result in Mycoplasma IgM antibody test were classified into the viral group (98 patients with respiratory virus) and the bacterial group (46 patients with the bacteria detected in the blood sputum culture or antibiotic treatment except macrolide improved the patient's condition). These groups were compared and analyzed using clinical, hematological, and radiographic differences and scoring system. Results: Clinical, hematological, and radiographic characteristics of Mycoplasma pneumoniae pneumonia have shown the intermediate level results between bacterial pneumonia and viral pneumonia. In terms of scoring system, the mean score of Mycoplasma pneumoniae pneumonia was 4.23, which was the intermediate level between bacterial pneumonia (mean score=6.67) and viral pneumonia (mean score=1.48). Conclusion: Results suggest that the combination of the scoring system information can increase the accuracy in the diagnosis even if they may have difficulties on diagnosis, because clinical manifestations, hematological, and radiographic findings are nonspecific.