• Pediatric Infection and Vaccine
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• v.9 no.2
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• pp.163-174
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• 2002

Background : To delineate the changes in the causative agents of neonatal sepsis and their antimicrobial susceptibilities in the neonatal intensive care unit and nursery of Hanyang University Hospital during the past 10 years. Methods : Hospital records of 15,144 patients hospitalized at the NICU and nursery of Hanyang University Hospital from 1989 to 1998 were reviewed and neonates diagnosed of neonatal sepsis were sorted and included in the study. The study period was divided into Period A(the first 5 years) and Period B(the second 5 years) to analyse causative agents and their antimicrobial susceptibilities. Results : Neonatal sepsis was diagnosed in 170 patients(1.1%{Period A 1.2%, Period B 1.0%}) among the total of 15,144 inpatients. Two hundred isolates(Period A 109 isolates, Period B 91 isolates) were identified in 186 blood cultures(Period A 99 cultures, Period B 87 cultures) from 170 patients(Period A 91 patients, Period B 79 patients). The average age at the onset of the disease, when the initial blood culture was drawn, was 12.3 days old(Period A 8.8 days, Period B 16.3 days), and the proportion of the early onset disease was 34.7% in Period A and 23.0% in Period B, indicating that neonatal sepsis developed earlier during Period A. Among the isolated organisms including Gram positive bacteria[132(66.0%)], Gram negative bacteria [60(30.0%)], and fungi[8(4.0%)], coagulase negative Staphylococcus(CNS) was the most common organism(69/34.5%), followed by Staphylococcus aureus(36/18.0%), Klebsiella pneumoniae(17/8.5%), Enterococcus(12/6.0%), Enterobacter cloacae(8/4.0%), Escherichia coli(6/3.0%), and Pseudomonas aeruginosae(5/2.5%). The isolated fungi were Candida parapsilosis, Candida albicans, and Trichosporon pullulans. CNS, S. aureus and Acinetobacter baumannii were isolated more frequently in Period A compared to Period B. Antimicrobial susceptibilities of CNS and S. aureus to methicillin and the first generation cephalo sporins were decreased in Period B compare to Period A, those to aminoglycosides were increased in Period B, and vancomycin resistant strains were not identified. K. pneumoniae, Enterococcus, E. coli, and P. aeruginosa were isolated less frequently in Period B, compared to Period A. For K. pneumoniae, antimicrobial susceptibilities to the first generation cephalosporins were low in both Periods A and B, those to tobramycin and gentamicin were increased in Period B, and those to amikacin, ceftriaxone, and trimethoprim-sulfamethoxazole were high in both Periods A and B. Antimicrobial susceptibilities of Enterococcous to ampicillin, penicillin, and the first generation cephalosporins were decreased in Period B, but vancomycin resistant strains were not identified. Conclusion : The occurrence rate of neonatal sepsis during the past 10 years in the NICU and nursery of the Hanyang University hospital was 1.1%, and the most common causitive agents were CNS and S. aureus, to which the antimicrobial susceptibilities to the first line drugs decreased in the later half of the study period with no vancomycin resistant isolates identified. Group B Streptococcus known to be the most common agent causing neonatal sepsis was not identified, and K. pneumoniae was isolated more commonly during the later half of the study period without decreased antimicrobial susceptibilities.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.309-321
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• 1987

For the investigation of microbiological and immunological specificity of Bacteroides gingivalis, Bacteroides gingivalis were isolated, enumerated and characterized from 13 Korean rapidly progressive periodontitis and 7 healthy control by anaerobic culture technique. The total proportion of black-pigmented Bacteroides from Korean R.P.P. patients and healthy control were 8.78% and 0.92%, respectively, among total isolated black-pigmented Bacteroides. In antibiotic susceptibility test, Bacteroides gingivalis isolated from R.P.P. patients were sensitive to Ampicillin and Tetracycline, and resistant to Gentamicin and Erythromycin in disc diffusion method. In antibiotic broth dilution method, the minimum inhibitory concentration(MIC) to Bacteroides gingivalis was 2 unit/ml of Penicillin and $0.25{\sim}1{\mu}g/ml$ of Tetracycline, respectively. The concentration of serum IgG in rapidly progressive periodontitis patients were sigificantly higher than that of healthy control, and concentration of diluted gingival crevicular IgG has not any significant differences between two groups. Serum and gingival crevicular IgG antibody to Bacteroides gingivalis were significantly higher titer in rapidly progressive periodontitis patients to compare with healthy control. The lipopolysaccharide profiles of 2 Korean B. gingivalis in silver stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis were similar to type strains of B. gingivalis and typical LPS band were appeared around the 24-Kd molecular weight. Immunodiffusion test and immunoelectrophoresis of the L.P.S. extracted from 2 Korean B. gingivalis and 2 kinds of type strains of B. gingivalis showed that B. gingivalis Korean-1 was reacted identically to B. gingivalis ATCC 33277. In trypsin and ${\alpha}$-glucosidase activity test of 2 Korean B. gingivalis, both of them revealed positive trypsin and negative ${\alpha}$-glucosidase activity, respectively. These investigation suggested that B. gingivalis is important pathogenic plaque bacteria for the pathogenesis of periodontitis and further study is needed to purify and characterize of the species-specific antigens of this organisms to develop monoclonal antibody and potential diagnostic reagents.

• Korean Journal of Veterinary Service
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• v.28 no.2
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• pp.121-146
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• 2005

Newcastle disease (ND), infectious bronchitis (IB), low pathogenic avian Influenza (LPAI) and fowl typhoid (FT) have been known as egg drop laying diseases because of the serious layer damage from mass zone layer. In this study, such egg drop laying diseases were investigated. To access this study, we peformed to evaluate antibody titers in serum and isolated bacteria and virus from organs and feces on May, July and September in 2003. The distribution of ND from January to May, IB and LPAI from October to February of the next year, and FT from March to September were inspected by the question survey in 21 farms. ND revealed to be positive rates of 490 to 474 $(96.7\%)$ in May, 510 to 506 $(99.2\%)$ in July and 510 to 510 $(100\%)$ in September with hemagglutination inhibition (HI) test. The mean antibody titers were 10.2, 9.9 and 10.2, respectively. With regard to IB, 484 out of 490 samples $(98.7\%)$ in May, 508 of 510 $(99.6\%)$ in July and 509 of 510 $(99.8\%)$ in September showed positive results and the mean antibody titers were gradually increased with 8.2, 9.0 and 9.4, respectively. According to HI test of LPAI, the positive results were shown in 442 of 480 $(92.1\%)$, 394 of 494 $(79.8\%)$ and 402 of 483 $(83.2\%)$ in May, July and September, respectively The mean antibody titers were decreased with 4.6, 4.3 and 4.0. The distribution of LPAI also elicited the positive rates of 480 to 475 $(99.0\%)$ in May, 494 to 485$(98.2\%)$ in July, 483 to 472 $(97.7\%)$ in September as determined by ELISA and the mean S/P ratio were 2.319, 2.557 and 2.380, respectively. Compared ELISA results with HI test of LPAI the positive results were 480 to 422 $(92.1\%),\;475(99.0\%),\;494\;to\;394 (79.8\%),\;485 (98.2\%)\;and\;483\;to\;402(83.2\%),\;472(97.7\%)$. Therefore, the positive rate determined by ELISA was higher than that of HI test with 6.9, 18.4 and $14.5\%$, respectively. When performed RT-PCR for ND using organ and feces samples, the pathotypes were detected $5(15.6\%)\;in\;May,\; 2(5.3\%) in\;July,\;2(7.1\%)$ in September but there is no samples showing positive band for LPAI. In attempt to isolate Salmonella gallinarum, bacteria were obtained from 4 cases (12.5%) in May, 9 (23.6%) in July, 5 (17.8%) in September. Thus the highest rate for isolation revealed to be shown in July When evaluated the antimicrobial susceptibility to 18 isolated strains of 5. gallinarum, bacteria were sensitive to trimethoprim/sulfamethox$(61.1\%),\;kanamycin\;(55.5\%),\;ampicillin\;(55.5\%)$ and amoxacillin/clavulanic acid $(55.5\%)$, cephalothin $(50.0\%)$, but resistant to penicillin $(88.9\%)$, streptomycin $(88.9\%)$, erythromycin $(83_4\%)$ and tetracycline $(61.1\%)$. According to HI test of ND and LPAI using captured 164 wild Korean tree sparrows (Passer nontanus), the positive rates were $47.6\%\;and\;57.3\%$, and the mean HI titers were 5.32 and 4.02, respectively. 71 $(43.2\%)\;and\;58(35.3\%)$ in captured sparrows also showed more than 4 titers for HI test to ND and LPAI, respectively However, the attempt for isolation of viruses failed in all samples.

• Journal of Life Science
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• v.22 no.8
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• pp.1114-1119
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• 2012

Bacteria are frequently contaminated during the collection and processing procedures of boar semen. Of the contaminants, Stenotrophomonas (S.) maltophilia is a Gram-negative bacterium that is widely distributed in a variety of habitats. Although PCR assays have been developed for the detection of S. maltophilia, they cross-react with some species of Xanthomonas. In this study, we designed a primer set for the detection of S. maltophilia in order to target the chiA (GenBank accession no. NC_010943) gene. The specific PCR products were amplified from S. maltophilia only, not from other tested strains that are frequently found in semen. The detection limit of the PCR was $1.5{\times}10^3$ CFU/ml with pure-cultured S. maltophilia and $1.5{\times}10^4$ CFU/ml with S. maltophilia spiked in semen. Twenty-six (5.9%) S. maltophilia were isolated from 440 semen samples. The PCR results exhibited 98.9% agreement with a comparison of S. maltophilia isolation. Also, the sensitivity and specificity of the PCR were 100% and 98.7%, respectively. In the antimicrobial susceptibility test, S. maltophilia isolates were highly susceptible to enrofloxacin and florfenicol, while the majority of them were resistant to amoxicillin/clavulanic acid, apramycin, ceftiofur, penicillin, and spectinomycin. These results indicated that the PCR using the chiA gene was proven to be reliable and effective for the detection of S. maltophilia with high levels of sensitivity and specificity.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.71-76
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• 1998

To know the antibiotic specificity of a Dinoflagellate, Cochlodinium polykrikoides, we investigated the survival time of C. polykrikoides against several concentrations of antibiotics and judged the selective specificity of antibiotics based on the $LT_50$ ($50\%$ of lethal time). The result showed that C. polykrikoides was sensitive to tetracycline and chloramphenicol, and resistant to polymixin-B, ampicillin, penicillin-G, dihydrostreptomycin, and neomycin. In the case of sensitive antibiotics to C. polykrikoides, tetracycline and chloramphenicol, the safety concentrations of both antibiotics were determined and the antibiotic specificity based or the plotted survival curve was analyzed. Before antibiotic treatment, we tested the antibiotic susceptibility of the contaminated bacterial population in tile culture of C. polykrikoides, and decided the proper kinds of antibiotics and concentrations before percoll-centrifugation. By percoll-centrifugation, we reduced bacteria, removed fungi, collected the algal pellet, and made axonic culture by antibiotic cascade procedure based on the result of antibiotic susceptibility test. We observed that axonic C. polykrikoides culture entered the logarthmic phase of growth when cell density was over 740 cells/ml and propagated to 5,800 cells/ml maximally. Divisions per day, k value of C. polykrikoides represented a good index for growth at the low density of cells. There was a highest k value shift before reaching to the logarithmic phase. We suggested that the preceeding highest k value shift stage is a good indicator for accurate broadcasting for red. tide blooming in the field, and the stage is also a good time for controlling red tide blooming in the filed, either.