• Tuberculosis and Respiratory Diseases
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• v.53 no.2
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• pp.173-182
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• 2002

Background : Nontuberculous mycobacteria (NTM) have usually been considered to be contaminants of colonizers when isolated from respiratory specimens in Korea, where there is a high prevalence of tuberculosis and a low rate of HIV infections. Therefore, there has been few studies on the clinical significance of NTM species in immunocompetent patients were investigated. Methods : Thirty-five NTM isolates, for which species identification was requested by the treating physicians during 1999 at the Asan Medical Center, were retrospectively analyzed. They were identified to the species level by mycolic acid analysis using high-performance liquid chromatography. The medical records of the patients with the NTM isolates were reviewed to identify those patients who met the American Thoracic Society (ATS)'s criteria for mycobacterial pulmonary infection. Their antimicrobial susceptibility data were compared with the clinical outcomes. Results : The NTM were identified as M. intracellulare (6 isolates), M. avium (5), M. abscessus (5), M. gordonae (5), M. terrae complex (4), M. szulgai (2), M. kansasii (2), M. fortuitum (2), M. peregrinum (1), M. mucogenicum (1), M. celatum (1), and M. chelonae (1). All 35 patients showed clinical symptoms and signs of chronic lung disease, but none had a HIV infections; 16 (45.7%) patients were found to be compatible with a NTM pulmonary infection according to the ATS criteria, 5 and 4 cases were affected with M. intracellulare and M. abscessus, respectively; 8 patients had a history of pulmonary tuberculosis. 13 patients received antimycobacterial therapy for an average of 21 months and 9 patients were treated with second-line drugs. Only 4 patients had improved radiologically. Conclusion : A NTM should be considered a potential pathogen of pulmonary infections in immunocompetent patients with chronic pulmonary diseases. Most NTM infections were left untreated for a prolonged period and showed a poor outcome as a result, M. intracellulare and M. abscessus were the two most frequent causes of NTM pulmonary infections in this study. Species identification and antimycobacterial susceptibility tests based on the species are needed for the optimum management of a NTM pulmonary infection in patients.

• 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.

• Journal of fish pathology
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• v.36 no.2
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• pp.263-275
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• 2023

Chum salmon (Oncorhynchus keta) is a species which returns to Korea for spawning and was produced as seed production at the Fisheries Resources Agency located in Uljin-gun, Gyeongsangbuk-do to preserve the species. However, farmed chum salmon showed symptoms of bacterial infection. Therefore, in this study, bacteria were isolated to identify the causative agent from chum salmon in October 2021. The isolated bacteria were identified based on the sequences of 16S rDNA, rpoD (RNA polymerase sigma factor σ⁷⁰), and vapA (A-layer) genes. Also, salinity-growth curve, biochemical characterization, antibiotic susceptibility test, and pathogenicity analysis were performed in four strains. As a result, four isolated strains were identified as Aeromonas salmonicida subsp. salmonicida. Additionally, the bacterial strains showed a decrease in growth as the salt concentration increased in the medium. All of the isolated strains exhibited γ-hemolysis, and the same biochemical properties. In the antimicrobial susceptibility test, all strains showed an inhibition zone of 40 to 44 mm for oxolinic acid, flumequine, and florfenicol. Pathogenic factors were assessed by RT-PCR at the mRNA level, and found that the four strains expresses the outer membrane ring of T3SS (ascV), inner membrane ring of T3SS (ascC), vapA, enterotoxin (act), and lipase (lip) genes which are well known to significantly contribute to the pathogenicity of A. salmonicida. The results of this study can be used as basic data to prevent A. salmonicida subsp. salmonicida occurring in sea-chum salmon in the future.

• Clinical and Experimental Pediatrics
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• v.50 no.1
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• pp.56-64
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• 2007

Purpose : This study was performed to identify the etiologic agents and antimicrobial susceptibility patterns of organisms responsible for bloodstream infections in pediatric cancer patients for guidance in empiric antimicrobial therapy. Methods : One hundred and ninety-seven episodes of bloodstream infections that developed in 128 pediatric cancer patients were analyzed, which were identified at the Seoul National University Children's Hospital during a 4 year-period from 2002 to 2005. Results : A total of 214 pathogens was isolated, of which 64.0 percent were gram-negative, 31.3 percent were gram-positive bacteria, and 4.7 percent were fungi. The most common pathogens were Klebsiella spp. (21 percent) and Escherichia coli (16.8 percent), and coagulase-negative staphylococci (CNS, 7.9 percent) and viridans streptococci (7.5 percent) emerged as important pathogens. Neutropenic patients were more often associated with gram-negative bacteria than non-neutropenic patients (67.5 percent vs. 51.1%, P=0.018) and patients with central venous catheters were more often associated with CNS and viridans streptococci than those without. Resistance rates of gram-positive bacteria to penicillin, oxacillin and vancomycin were 83.3 percent, 48.5 percent and 0.5 percent, respectively, and those of gram-negative bacteria to cefotaxime, piperacillin/tazobactam, imipenem, gentamicin and amikacin were 24.1 percent, 17.2 percent, 6.6 percent, 21.6 percent, and 14.2 percent, respectively. Gram-negative bacteremias were more often associated with intensive care than gram-positive bacteremias (26.5 percent vs. 10.3 percent, P=0.016), and patients with catheters were more often associated with intensive care (34.4 percent vs. 10.8 percent, P<0.001) and higher fatality rate (16.7 percent vs. 4.8 percent, P=0.012) than those without. Conclusion : This study revealed that gram-negative bacteria are still a dominant organism in bloodstream infections, especially in neutropenic patients, and confirmed that gram-positive bacteria are emerging as important etiological agents in bloodstream infections of pediatric hemato-oncologic patients.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.173-180
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• 2017

This study evaluated the characteristics of rice cookies with varying amounts (0, 250, 500, and 750 mg) of dandelion complex powder. Dandelion powder is considered a functional food with skin-moisturizing and atopic skin improvement effects by KFDA. Quality characteristics of AF343 and rice cookies were measured by determining antimicrobial activities, physical characteristics, sensory evaluation values, and antioxidant activities. An antibiotic susceptibility test of the powder showed positive activities in Escherichia coli (O157:H7), Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes. Rice cookie containing 250-500 mg powder showed significantly increased antioxidant activities compared to controls (p<0.05). However, sensory intensities between the two sample groups were not significantly different. Thus, rice cookies containing 250-500 mg dandelion complex powder were successfully developed to improve antioxidant and antimicrobial qualities. These products may attract the attention of health-conscious consumers in the highly competitive cookie industry.

• Pediatric Infection and Vaccine
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• v.19 no.3
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• pp.131-140
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• 2012

Purpose : This study was performed to identify the etiologic agents and antimicrobial susceptibility patterns of organisms responsible for bloodstream infections in pediatric cancer patients for guidance in empiric antimicrobial therapy. Methods : A 5-year retrospective study of pediatric hemato-oncologic patients with bacteremia in Seoul National University Children's Hospital, from 2006 to 2010 was conducted. Results : A total of 246 pathogens were isolated, of which 63.4% (n=156) were gram-negative, bacteria 34.6% (n=85) were gram-positive bacteria, and 2.0% (n=5) were fungi. The most common pathogens were Klebsiella spp. (n=61, 24.8%) followed by Escherichia coli (n=31, 12.6%), coagulase-negative staphylococci (n=23, 9.3%), and Staphylococcus aureus (n=22, 8.9 %). Resistance rates of gram-positive bacteria to penicillin, oxacillin, and vancomycin were 85.7%, 65.9%, and 9.5%, respectively. Resistance rates of gram-negative bacteria to cefotaxime, piperacillin/tazobactam, imipenem, gentamicin, and amikacin were 37.2%, 17.1%, 6.2%, 32.2%, and 13.7%, respectively. Overall fatality rate was 12.7%. Gram-negative bacteremia was more often associated with shock (48.4% vs. 11.9%, P<0.01) and had higher fatality rate than gram-positive bacteremia (12.1% vs. 3.0%, P=0.03). Neutropenic patients were more often associated with shock than non-neutropenic patients (39.6 % vs. 22.0%, P=0.04). Conclusion : This study revealed that gram-negative bacteria were still dominant organisms of bloodstream infections in children with hemato-oncologic diseases, and patients with gram-negative bacteremia showed fatal course more frequently than those with gram-positive bacteremia.

• Journal of environmental and Sanitary engineering
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• v.3 no.2 s.5
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• pp.23-41
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• 1988

Two hundred and eighty-six strains of Salmonella species were isolated from the twelve provincial institutes of health and 19 general hospitals of urban and rural areas in Korea from January to December in 1986. The antimicrobial susceptibility test of these cultures was done by the method of agar diluton. The resistance frequency of Salmonella cultures was $29.7\%$. Among these resistant cultures, the most provalent resistance pattern of Salmonella was ampicillin, carbenicillin, chloramphenicol, tetracycline, streptomycin, and its resistance frequency was $15\%$. In plasmid profile of resistance strains, average number of plasmid harboring in Salmonella was 1-4 and molecular weight of plasmid ranged 1.6 to 70 megadalton (Md.). Plasmid pattern of strains isolated from Seoul and Kang-won showed the same or similar profiles. Plasmid pattern was identical in the same resistance pattern.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.217-224
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• 2004

This study was carried out to investigate the antibiotic resistance pattern of Listeria spp. and Staphylococcus aureus. A total of 17 (14.8%) L. monocytogenes, 13 (11.3%) L. innocua, 7 (7%) L. welshimeri, and 83 (72.2%) S. aureus were isolated from commercial poultry carcasses in Seoul and Kyonggi province during the period between 2001 and 2003. Antibiotic susceptibility test of all Listeria strains isolated was performed by the disk agar diffusion method. Antibiotics used in the study were as follows; Amikacin (An), Ampicillin (Am), Cephalothin (Cf), Chloramphenicol (C), Ciprofloxacin (Cip), Erythromycin (E), Gentamicin (Gm), Imipenem (Ipm), Kanamycin (K), Minocycline (Mi), Neomycin (N), Norfloxacin (Nor), Ofloxacin (Ofx), Penicillin (P), Streptomycin (S), Tetracycline (Te), Tobramycin (Nn), Trimethoprim (Tmp), Trimethoprim/Sulfamethoxazloe (Sxt), and Vancomycin (Va). The antibiotic resistance pattern of S. aureus isolates was performed by the disk agar diffusion method. For the latter program, antibiotics used to the study were as follows; Cf, C, Cip, Clindamycin (Cc), E, Gm, Ipm, Nafcillin (Nf), Oxacillin (Ox), P, Te, Sxt, and Va. Of the 17 L. monocytogenes isolates, 94.1% were resistant to Te, 88.2% to Mi, 11.8% to Nor, 11.8% to S, 5.9% to Cip, and 5.9% to C. Of 13 L. innocua, 53.8% were resistant to Te, 23.1% to Mi, 23.1% to S, 7.7% to Cip, and 7.7% to Nor. Of 7 L. welshimeri, 57.1% were resistant to Te, and 14.3% to Am. Of 83 S. aureus, 100% were resistant to Te, 86.7% to Gm, 34.9% to P, 15.7% to Cip, 12% to Cc, 9.6% to E. The multiple antibiotic resistance patterns of L. monocytogenes isolates were observed in Te Mi Cip (5.9%), Te Mi Nor (5.9%), Te Mi (76.5%), and Te Nor (5.9%). Multiple antibiotic resistance was also found in L. innocua isolates. Resistant to Te Mi S Cip Nor was 7.7%, Te Mi S (7.7%), Te Mi (7.7%), and was 7.7% to Te S. Antibiotic resistance patterns for S. aureus isolats were demonstrated to Te Gm P Cip Cc E (6.0%), Te Gm Cip Cc E (3.6%), Te Gm P Cc (1.2%), Te Gm P (15.6%), Te Gm Cip (2.4%), Te P Cip (2.4%), Te Gm Cc (1.2%), Te Gm (56.6%), Te P (9.6%), and to Te Cip (1.2%). The results of this study suggest a high incidence of Lsteria spp. and S. aureus on poultry carcasses. The contaminated poultry carcasses may be a potential vehicle for foodborne infections due to multiple antimicrobial resistant organisms.

• Journal of agricultural medicine and community health
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• v.30 no.2
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• pp.137-149
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• 2005

Objectives and Methods: This study was performed to investigate the etiologic bacterial, viral and protozoal organisms for the diarrhea from hospitals in Chungnam area from January to December in 2004. Total of 787 fecal samples were collected and examined. Results and Conclusions: In test for enteropathogenic bacteria, total of 79 cases out of 787 samples from hospitals showed positive isolation. Among 79 positive samples, 27 cases were confirmed as Salmonella spp.. 20 cases as pathogenic E. coli, 18 cases as Clostridium perfringens, 6 cases as Staphylococcus aureus, 4 cases as Shigella spp. and 4 cases as Vibrio parahaemolyticus. In test for enteropathogenic virus, 190 cases out of 787 samples from hospitals showed positive reaction. Among 190 samples, 115 cases were confirmed as rotavirus, 55 cases as norovirus, 5 case as astrovirus, 4 case as rotavirus & norovirus, 3 cases as adenovirus, 2 case as rotavirus & astrovirus. In test for enteropathogenic protozoa, 6 cases out of 787 samples from hospitals showed positive result. Among 6 samples, 5 cases were confirmed as Entamoeba histolytica and 1 cases as Giardia lamblia. When we classified the positive results by the age of the patients, the highest isolation rate was noted in a group of age under 10 and over 60 for bacterial, viral and protozoal pathogens. Especially, patient below age of 5 showed high positive rate. When we classified the positive results by the time, pageathogenic bacteria were isolated throughout the year, and the highest frequency was noted in August. On the other hand, pathogenic viruses were detected more frequently during the colder season from December to April. Antimicrobial susceptibility test for the isolated bacteria resulted as follows; Salmonella strains showed high drug resistance rates against ampicillin, chloramphenicol, tetracycline, nalidixic acid, ticarcillin. Shigella strains showed high drug resistance rates against ampicillin, trimethoprim/sulfamethoxazole, chloramphenicol, tetracycline, ampicillin/sulbactam, ticarcillin. Pathogenic E. coli strains showed high drug resistance rates against ampicillin, cephalothin, gentamicin, tetracycline, nalidixic acid, ampicillin/sulbactam, ticarcillin.

• Pediatric Infection and Vaccine
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• v.13 no.1
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• pp.71-77
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• 2006

Purpose : Shigellosis is still an important cause of acute food-borne diarrheal diseases throughout the world. We investigated the transmission routes and clinical course through the outbreak of shigellosis in Mapo-Gu, Seoul. Methods : From October 7th to November 19th in 2005, Mapo-Gu public health center had referred 32 patients with confirmed or suspected shigellosis to the National Medical Center. We had investigated source of infection, epidemiology, laboratory findings, and clinical course of the cases occurred during this outbreak. Results : Among 32 patients, 24 patients had been confirmed with shigellosis, 8 patients had been diagnosed with suspected shigellosis. They ranged in age from 5 months to 12 years old and their mean age was 6.5 years. The clinical manifestations were as follows; diarrhea, fever, abdominal pain and asymptomatic condition. Symptoms had sustained for 3.7 days on the average. S. sonnei were cultured by rectal swab and founded to be resistant to ampicillin and TMP/SMX except to 3rd generation cephalosporin. After treatment with antibiotics such as cefixime and ceftriaxone or imipenem and conservative treatment with electrolyte and fluid replacement for 5~7 days, Stool cultures of the rectal swab grew no Shigella in these cases except 3 cases. Conclusion : An outbreak of shigellosis had occurred in a preschool and elementary school children. From the same results of antimicrobial susceptibility and pulsed-field gel electrophoresis patterns in this study, we suggest that the outbreak of shigellosis in this report had been originated from a single strain. According to all negative results about suspected food and water cultures, we couldn't find out source of infection. Through materials offerred by Mapo-Gu Public Health Center, we presumed the trasmission routes probably were person-to-person.