• Pediatric Infection and Vaccine
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• v.18 no.1
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• pp.31-39
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• 2011

Purpose : This study was performed for the purpose of finding causative organisms and clinical features of septic arthritis or acute osteomyelitis in children. Methods : The study involved a retrospective review of the medical records of 63 microbiologically confirmed cases of acute pyogenic arthritis and osteomyelitis. All of the cases were brought about by community-associated infections and managed at the Seoul National University Children's Hospital or Seoul National University Bundang Hospital from June 2003 to July 2009. Results : The median age of all cases was 60 months and there were 35 males and 28 females. Major involved joints included the hip joint (15 cases), knee joint (7 cases), shoulder joint (4 cases), and elbow joint (4 cases). Also, major involved bones included the femur (20 cases), tibia (13 cases), humerus (7 cases), and radius (7 cases). Staphylococcus aureus was the most commonly identified causative organism, accounting for 49 cases (77.8%). Of the 49 isolates of S. aureus, methicillin-resistant S. aureus (MRSA) accounted for 8 cases (16.3%). Group B streptococcus spp. (GBS) and Salmonella spp. accounted for 3 cases, respectively. Nafcillin or cefazolin was often prescribed as an initial empirical antibiotic. There were 9 cases that were managed by a regimen that included vancomycin as the first choice. Fifty four cases (85.7%) recovered without any complications. Methicillin-sensitive S. aureus (MSSA), responsible for 41 cases, caused chronic complications in 3 cases. Of 8 cases caused by MRSA, 1 case showed chronic complication. There were no fatal cases. Conclusion : S. aureus remains the most common organism causing acute pyogenic arthritis and osteomyelitis of childhood acquired in the community. The high prevalence of methicillin resistance among S. aureus should be considered carefully in the selection of initial empirical antibiotics.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.1-15
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• 2005

Pathogens, insects and weeds have significantly reduced agricultural productivity. Thus, to increase the productivity, synthetic agricultural chemicals have been overused. However, these synthetic compounds that are different from natural products cannot be broken down easily in natural systems, causing the destruction of soil quality and agricultural environments and the gradually difficulty in continuous agriculture. Now agriculture is faced with the various problems of minimizing the damage in agricultural environments, securing the safety of human health, while simultaneously increasing agricultural productivity. Meanwhile, plants produce secondary metabolites to protect themselves from external invaders and to secure their region for survival. Plants infected with pathogens produce antibiotics phytoalexin; monocotyledonous plants produce flavonoids and diterpenoids phytoalexins, and dicotylodoneous plant, despite of infected pathogens, produce family-specific phytoalexin such as flavonoids in Leguminosae, indole derivatives in Cruciferae, sesquitepenoids in Solanaceae, coumarins in Umbelliferae, making the plant resistant to specific pathogen. Growth inhibitor or antifeedant substances to insects are terpenoids pyrethrin, azadirachtin, limonin, cedrelanoid, toosendanin and fraxinellone/dictamnine, and terpenoid-alkaloid mixed compounds sesquiterpene pyridine and norditerpenoids, and azepine-, amide-, loline-, stemofoline-, pyrrolizidine-alkaloids and so on. Also plants produces the substances to inhibit other plant growths to secure the regions for plant itself, which is including terpenoids essential oil and sesquiterpene lactone, and additionally, benzoxazinoids, glucosinolate, quassinoid, cyanogenic glycoside, saponin, sorgolennone, juglone and lots of other different of secondary metabolites. Hence, phytoalexin, an antibiotic compound produced by plants infected with pathogens, can be employed for pathogen control. Terpenoids and alkaloids inhibiting insect growth can be utilized for insect control. Allelochemicals, a compound released from a certain plant to hinder the growth of other plants for their survival, can be also used directly as a herbicides for weed control as well. Therefore, the use of the natural secondary metabolites for pest control might be one of the alternatives for environmentally friendly agriculture. However, the natural substances are destroyed easily causing low the pest-control efficacy, and also there is the limitation to producing the substances using plant cell. In the future, effects should be made to try to find the secondary metabolites with good pest-control effect and no harmful to human health. Also the biosynthetic pathways of secondary metabolites have to be elucidated continuously, and the metabolic engineering should be applied to improve transgenics having the resistance to specific pest.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.428-436
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• 2016

The emergence of antibiotic-resistant bacteria has been increased and become a public health concern worldwide. Many bacterial infections can be sequentially treated with different types of antibiotics. Thus, this study was designed to evaluate the changes in survival, antibiotic susceptibility, mutant frequency, ${\beta}$-lactamase activity, biofilm formation, and gene expression in Klebsiella pneumoniae after exposure to sequential antibiotic treatments of ciprofloxacin and meropenem. Treatments include control (CON; no addition), 1/2 MIC ciprofloxacin addition (1/2CIP), 2 MIC ciprofloxacin addition (2CIP), initial 1/2 MIC ciprofloxacin addition followed by 1/2 MIC meropenem (8 h-incubation) and 2 MIC ciprofloxacin (16 h-incubation) (1/2CIP-1/2MER-2CIP), initial 1/2 MIC ciprofloxacin addition followed by 1/2 MIC meropenem (8 h-incubation) and 2 MIC meropenem (16 h-incubation) (1/2CIP-1/2MER-2MER), and initial 1/2 MIC ciprofloxacin addition followed by 2 MIC ciprofloxacin(8 h-incubation) and 2 MIC meropenem(16 h-incubation) (1/2CIP-2CIP-2MER). No growth of K. pneumoniae was observed for the 2CIP throughout the incubation period. The numbers of planktonic cells varied with the treatments (7~10 log CFU/ml), while those of biofilm cells were not significantly different among treatments after 24-h incubation, showing approximately 7 log CFU/ml. Among the sequential treatments, the least mutant frequency was observed at the 1/2CIP-1/2MER-2CIP (14%). Compared to the CON, 1/2CIP-2CIP-2MER decreased the sensitivity of K. pneumoniae to piperacillin, cefotaxime, and nalidixic acid. The highest ${\beta}$-lactamase activity was 22 nmol/min/ml for 1/2CIP-1/2MER-2CIP, while the least ${\beta}$-lactamase activity was 6 nmol/min/ml for 1/2CIP-2CIP-2MER. The relative expression levels of multidrug efflux pump-related genes (acrA, acrB, and ramA) were increased more than 2-fold in K. pneumoniae exposed to 1/2CIP-1/2MER-2MER and 1/2CIP-2CIP-2MER. The results suggest that the sequential antibiotic treatments could change the antibiotic resistance profiles in K. pneumoniae.

• Tuberculosis and Respiratory Diseases
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• v.49 no.1
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• pp.72-81
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• 2000

Backgrounds : Authors evaluated the quantitative culture of bronchoalveolar lavage fluid(BALF) in patients who were being treated with antimicrobial agents and the characteristics of isolated microorganism. Method : A prospective study was done with 25 patients under mechanical ventilation and antimicrobial treatment in ICU and NCU of Yongdong Severance Hospital from Apr. to Sep. 1999. Patients were classified into two groups: control group (n=5) and patients with VAP (n=20). The threshold of quantitative culture of BAL fluid in the diagnosis of VAP was $10^4$ cfu/ml. Results : 1) In gram staining of BALF, one patient in the control group and four in the VAP group showed positive results. Quantitative culture of BALF showed no organisms in the patients in the control group and in 9 VAP patients. Therefore the overall sensitivity was 43.8%. 2) Frequency of isolated organisms cultured above diagnostic threshold was in the following order: E. cloaclae, S. aureus, K. pneumoniae, and A. baumani. S. aureus and Staphylococcus coagulase(-) were a11 resistant to oxacillin. Seven out of 10 isolated G (-) organisms were suspected to be organisms producing extended spectrum $\beta$-lactamase (ESBL). 3) The concurrence between gram staining of sputum aspiration and that of BALF was only in 1 case. And the concurrence of culture results was observed in 3 cases. Conclusion : The sensitivity of gram staining and quantitative culture of BALF from patients under antibiotic therapy and the concordance rate between conventional tracheal aspiration and BAL were low, facts which were important in interpretation the data. Since the frequency of drug resistance organisms was not different from that of foreign data, antibiotics must be prudently selected and used.

• Pediatric Infection and Vaccine
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• v.10 no.2
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• pp.208-214
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• 2003

Purpose : We performed a retrospective study on bacterial meningitis in children, pertaining to the causative organisms, bacterial resistance to antibiotics and the effect of recent introduction of Haemophilus influenzae type b(Hib) vaccine. Methods : We analysed the forty-three cases of bacterial meningitis which had been treated at the Inha University Hospital from June 1996 to June 2003. Results : Nineteen cases(44.2%) of them were infants younger than 2 months of age, and 29 cases(67.5%) younger than 1 year of age. The common causative organisms under 2 months of age were group B streptococcus(GBS)(47.4%), E. coli(21.1%), and Klebsiella pneumoniae(21.1%). In the age group beyond 2 months of age, S. pneumoniae were seen in 50 %, H. influenzae in 16.7% and N. meningitidis in 16.7%. All of the five cases of Hib meningitis had not been vaccinated for Hib. There has been no Hib meningitis cases since 2001. Overall fatality rate was 4.5%, and complication occurred in 39%. Complications was significantly less frequent in patients resumed to be treated within 48 hours after onset compared to after 48 hours after onset. Penicillin resistance of S. pneumoniae and GBS isolated among bacterial meningitis cases was high. Conclusion : Timing of treatment after the onset of the disease appeared the most important factor for prognosis of bacterial meningitis. The cases of H. influenzae meningitis have decreased probably due to Hib vaccination.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.134-141
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• 2005

To characterize genotypic and phenotypic traits of Staphylococcus aureus isolates (n = 86) from lettuces and raw milk, major virulence-associated genes and antibiotic susceptibility were detected using PCR-based methods and disk diffusion method, respectively. All isolates possessed coagulase gene and showed five polymorphism types [500 bp (2.4%), 580 bp (17.4%), 660 bp (61.6%), 740 bp (17.4%), and 820 bp (1.2%)] due to variable numbers of tandem repeats present within the gene. Two or three different loci of hemolysin gene family were dominant in isolates, 47 of which (55%) possessed combination of hla/hld/hlg-2 genes as the most prevalent types. Among enterotoxin-encoding genes, sea was detected from 32 isolates (37%), sed from 1 isolate (1%), and sea and sed genes were co-detected from 4 isolates (5%), whereas seb, sec, and tsst-1 genes were not detected. All isolates were susceptible to ciprofloxacin, trimethoprim/sulfamethoxazole, oxacillin, and vancomycin, 85 isolates (99%) to penicillin G, 54 isolates (63%) to chloramphenicol, 51 isolates (59%) to erythromycin, and 7 isolates (8%) to clindamycin. Among resistant isolates, seven displayed multiantibiotic-resistance against two different antibiotics.

• Tuberculosis and Respiratory Diseases
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• v.57 no.1
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• pp.19-24
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• 2004

Background : It is difficult to differentiate between tuberculous pneumonia and Community Acquired Pneumonia, so the diagnosis and treatment of tuberculous pneumonia can be delayed frequently. In this study, we attempted to retrospectively evaluate the clinical and radiologic characteristics of tuberculous pneumonia. Methods : We conducted a retrospective analysis of clinical characteristics of 58 patients diagnosed with tuberculous pneumonia from Nov. 1997 to May 2001 at Korea university kuro hospital. Result : The male to female ratio was 1:1 and the mean age at diagnosis was $54.5{\pm}18.6$ years. Fifty five patients were confirmed microbiologically and three patients pathologically. There were 20 patients(34.5%) who had diabetes mellitus(8cases), chronic obstructive pulmonary disease(3cases), malignancy(3cases), bronchiectasis(2cases), chronic renal failure(1cases) or long term history of corticosteroid treatment(3cases). Many patients had multilobar infiltration in chest X-ray, dominantly in the lower lobe. thirty two patients(55.2%) had infiltration in more than 2 lobes and 5 patients in more than 4 lobes. The significant correlation between the diabetes mellitus and the infiltrated Rt lower lobe(RLL) was found on the borders of confidence limit.(P=0.07<0.1). There was significant correlation between woman and infiltrated lobe(RML, RLL, LLL) excluding the both upper lobe(P=0.029). Conclusion : We must consider tuberculous pneumonia when lobar pneumonia with consolidation resistant to antibiotics, especially in the patients who have diabetes mellitus, chronic obstructive pulmonary disease, malignancy, bronchiectsis, chronic renal failure or long term history of corticosteroid treatment.

• Tuberculosis and Respiratory Diseases
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• v.61 no.1
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• pp.13-19
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• 2006

Background: Acinetobacter baumannii has emerged as an important nosocomial pathogen worldwide. The incidence of these infections has recently begun to increase. The mortality rate associated with these infections is high (bacteremia; 52%, pneumonia: 23%~73%) and multidrug resistance has been reported. For the effective control of multidrug-resistant Acinetobacter baumannii(MDR-AB), the impact of these organisms in clinical practice should be determined. This study compared the clinical characteristics, mortality and morbidity of Acinetobacter nosocomial pneumonia between MDR strain and non-MDR strain. Methods: From Jan. 1, 2002 to Nov. 1. 2004, 47 adult patients with Acinetobacter nosocomial pneumonia in Chuncheon Sacred Heart Hospital were recruited and analyzed retrospectively. MDR-AB was defined as showing in vitro resistance to all commercially available antibiotics against A. baumannii. Results: There were 47 patients with Acinetobacter nosocomial pneumonia. MDR-AB and non MDR-AB was the cause of the pneumonia in 17 and 30 patients, respectively. Mean age of the former was $69{\pm}11$ years old and the latter was $70{\pm}13$ years old. The mean APCHE II score, ICU days and mortality were not different between the two groups ($16.1{\pm}5.4$ vs. $14.9{\pm}4.8$, P=0.43, $25.1{\pm}13.6$ vs. $39.1{\pm}31.0$, P=0.2, 58.8% vs. 40%, P=0.21). Conclusion: There are no significant differences in mortality and morbidity between MDR and non-MDR Acinetobacter baumannii. The mortality of the two groups is surprisingly high, therefore proper infection control practices are essential.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.285-295
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• 2014

This study was conducted to survey the epidemiological characteristics and the isolated strains for pathogenic E. coli which was the major causative organisms for food poisoning occurred at school food services in the Gyeonggi-do area during the past three years. We investigated 19 accidents of food-borne disease outbreaks by pathogenic E. coli at school food services from 2010 to 2012. Food-borne disease outbreaks by pathogenic E. coli were usually occurred at direct management type (18 accidents, 95%) and high schools. For the seasonal factors, 13 accidents (65%) were occurred in June to September, especially the end of August and September after the summer holidays. The first patients were occurred on Wednesday (7 accidents, 37%) and Thursday (7 accidents, 37%), and they were mainly reported on Thursday (7 accidents, 37%) and Friday (5 accidents, 26%). The exposure of risk was estimated in Monday (4 accidents, 21%), Tuesday (7 accidents, 37%) and Wednesday (4 accidents, 21%), and kimchi (5 accidents, 50%) was estimated as the food of the high risk responsible for the outbreaks. 98 isolates of pathogenic E. coli consisted of PEC (50%), ETEC (34%), EAEC (15%), and EHEC (1%). The antibiotic resistance of pathogenic E. coli showed in the descending order of ampicilline (40%), nalidixic acid (37%), trimethoprim/sulfamethoxazole (24%), and tetracycline (19%). The antibiotics of second and third generation cephalosporins, cabarpenem, aminoglycosides, and second generation quinolones had antimicrobial susceptibilities and cefalotin, ampicillin/sulbactam and chloramphenicol showed medium resistance at 29%, 25%, and 6% respectively, and 70% of isolates were resistant to more than one antibiotic. By the PFGE analysis, they were classified into nine major groups and 31 profiles with 57% pattern similarity. It was very difficult to find the correlation of antimicrobial susceptibilities and genotype in the small scale-food poisoning, but the similarity of antimicrobial resistance and PFGE patterns in the large scale-food poisoning enabled the outbreaks to estimate the same pathotype of E. coli derived from identical origins.

• Journal of Life Science
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• v.17 no.3 s.83
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• pp.386-395
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• 2007

A total of 27 strains of Vibrio parahaemolyticus (18 strains isolated from Korea and 9 strains from Japan) were serotyped and examined for biochemical characteristics, antimicrobial susceptibility patterns, cytotoxicity assay, thermostable direct hemolysin (TDH) production and molecular epidemiology. Using polymerase chain reaction (PCR) method and DNA probe hybridization method, the strains were tested for toxR, tdh, trh and ORF 8 genes. The V. parahaemolyticus isolated from patients were belonged to 8 different serotypes : O3:K6, O1:K38, O3:K57, O4:K9, O4:Kl2, O4:K68, O5:Kl5 and O6:K46. Urease-positive strain possessed the trh gene, and conversely, urease-negative strains lacked the gene, indicating that urease production by V. parahemolyticus strains strongly correlates with the possession of the trh gene. Most strains showed multiple resistant to more than three antibiotics and the antibiogram could be classified into 6 group (I to VI). All of the O3:K6 strains isolated in South Korea and Japan producted TDH at high levels. The TDH titers ranged between 256 and 2.048, and the average titer was 1009. To distinguish the new and increasingly common V. parahaemolyticus strains from clinical isolates, ORF 8 is a useful genetic marker. After Southern hybridization, the HindIII restriction fragment patterns of the tdh gene were grouped one type, respectively. One type showed two bands one of which was 4.3kb and the other was 11.5kb in size. Variation between the O3:K6 serotype are minor when compared to the differences seen with the non O3:K6 strains. The migration patterns of Not I -digested of the total DNA of the O3:K6 strains were similar, and only slight variations were observed between the serotypes. By contrast, the O3:K6 strains and non O3:K6 had markedly different profiles. In conclusion, Random amplified polymorphic DNA (RAPD) profile using appropriate primers was an effective epidemiological marker.