• Journal of Microbiology and Biotechnology
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• v.34 no.8
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• pp.1617-1626
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• 2024

Various antibiotic-resistant bacteria (ARB) are known to induce repeated pulmonary infections and increase morbidity and mortality. A thorough knowledge of antibiotic resistance is imperative for clinical practice to treat resistant pulmonary infections. In this study, we used a reads-based method and an assembly-based method according to the metagenomic next-generation sequencing (mNGS) data to reveal the spectra of ARB and corresponding antibiotic resistance genes (ARGs) in samples from patients with pulmonary infections. A total of 151 clinical samples from 144 patients with pulmonary infections were collected for retrospective analysis. The ARB and ARGs detection performance was compared by the reads-based method and assembly-based method with the culture method and antibiotic susceptibility testing (AST), respectively. In addition, ARGs and the attribution relationship of common ARB were analyzed by the two methods. The comparison results showed that the assembly-based method could assist in determining pathogens detected by the reads-based method as true ARB and improve the predictive capabilities (46% > 13%). ARG-ARB network analysis revealed that assembly-based method could promote determining clear ARG-bacteria attribution and 101 ARGs were detected both in two methods. 25 ARB were obtained by both methods, of which the most predominant ARB and its ARGs in the samples of pulmonary infections were Acinetobacter baumannii (ade), Pseudomonas aeruginosa (mex), Klebsiella pneumoniae (emr), and Stenotrophomonas maltophilia (sme). Collectively, our findings demonstrated that the assembly-based method could be a supplement to the reads-based method and uncovered pulmonary infection-associated ARB and ARGs as potential antibiotic treatment targets.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1284-1289
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• 2007

The Biological Activated Carbon (BAC) process in the water treatments represents a kind of biofiltration process which capabilities of bacteria to remove organic matters are maximized. It enables to eliminate organic matters and effectively reduce microbial regrowth potentials. As attached bacteria employ natural organic matter as a substrate, they are significantly dependent on indigenous microorganisms. In this study, characteristics of bacterial community by culturable and unculturable Methods have been conducted in a pilot plant using SAC in water treatment process at the downstream of the Nakdong River. Based on the results, HPC and bacterial- production for coal-based activated carbon material were $1.20{\sim}56.2{\times}l0^7$ cfu/g and $1.2{\sim}3.7\;mgC/m^{3}h$, respectively, in the SAC process. The highest level of attached bacteria biomass and organic carbon removal efficiency was found in the coal-based activated carbon. The genera Pseudomonas, Flavobacterium, Alcaligenes, Acilzetobacter, and Spingomonas were identified for each activated carbon material. Pseudomonas vesicularis was the dominant species in the coconut- and coal-based materials, where as Pseudomonas cepacia was the dominant species in the wood-based material. The Scanning Electron Microscope (SEM) observation of the activated carbon surface also found the widespread distribution of rod form and coccus. The community of attached bacteria was investigated by performing Fluorescent in situ hybridization (FISH) analysis. a group was dominant in coal, wood and coccunt-based materials, ${\alpha},\;{\beta}\;and\;{\gamma}$ group ranged from 27.0 ${\sim}$ 43.0%, 7.1 ${\sim}$ 22.0%, 11.3 ${\sim}$ 28.6%, respectively. These results suggest that a group bacterial community appears to be regulated removal efficiency of organic material in water treatment process.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.74-80
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• 1996

This experiment was conducted to obtain the basis of degradation of remaining agricultural chemicals accumulated in upland soils of Honam district in Korea. The population. relative growth rate(RGR). chlorothalonil(TPN)-degradation ability and bacterialogical characteristics of TPN resistant strains were investigated in TPN levels of 0, 25, 50, 100 and $500{\mu}l/ml$ compared with Mancozeb. A number of TPN-resistant bacteria were differ in the area of examined and were decreased with higher levels of TPN. The resistance of bacteria was stronger in TPN than Mancozeb but the resistance of fungi was vise versa. RGR of bacteria in the culture was the highest at the level of $50{\mu}l/ml$ and the lowest in $500{\mu}l/ml$ of TPN. TPN-degradation ability of bacteda isolated in various TPN levels was varied : only 8 percentage of bacteria showed 75 percentage or more degradation ability. The higher the concentration in TPN resistance, the larger the number of strains carried great ability to decompose pesticide residues. The strains having higher decomposition ability was rod-shapes cells and senstive to heat. Analyses of the indol production, methyl red, and V-P test have given similar results, with negative reaction in all these strain, while the other biochemical characteristics were differ in the strains. Based on these, these strains might be classified into Pseudomonas sp., Corynebacterium sp., Acinetobacter sp. and Moraxcella sp.

• Tuberculosis and Respiratory Diseases
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• v.55 no.1
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• pp.59-68
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• 2003

Background : In intubated patients, cultures of endotracheal aspirates (EA) are apt to contamination throughout the endotracheal tube. Therefore, the identification of etiologic agents via conventional EA cultures is not always reliable. In order to differentiate a pulmonary infection from a non-infectious disease, and to identify the true etiologic agent of acute pulmonary infection, blinded protected specimen brushing (PSB) was used, and its efficacy evaluated. Methods : In 51 intubated patients, with suspected pneumonia, blind PSB were performed, and the results compared with blood and EA cultures. A protected specimen brush was introduced through the endotracheal tube, and settled at the affected large bronchus. A specimen brush was introduced to the expected region using the blind method. The tip of the brush was introduced with an aseptic technique after vigorously mixed for 1 minute in $1cm^3$ of Ringer's lactate solution. The specimens were submitted for quantitative culture within 15 minutes, with a culture being regarded as positive if the colony forming units were above $10^3/ml$. Results : Of the 51 patients, 15 (29.4%) had community-acquired pneumonia (CAP), 27 (52.9%) hospital-acquired pneumonia (HAP) and 9 (17.6%) non-infectious diseases. The sensitivity and specificity of the quantitative PSB culture for the diagnosis of pneumonia were 52.4 and 88.9%, respectively. The sensitivity and specificity of EA were 78.6 and 77.8%, respectively. The blind PSB was superior to the EA for the identification of true etiologic agents. Of 53 episodes of 27 HAP patients, MRSA (Methicillin-resistant staphylococcus aureus) (41.5%) was the most common causative agent followed by Pseudomonas aeruginosa (15.1%), Klebsiella sp. (7.5%) and Acinetobacter sp. (7.5%). Conclusions : As a simple, non-invasive diagnostic modality, the blind PSB is a useful method for the differentiation of a pulmonary infection from non-infectious diseases and to identify the etiologic agents in intubated patients. A blind PSB can be performed without bronchoscopy, so is safer, more convenient and cost-effectiveness for patients where bronchoscopy can not be performed.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.882-888
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• 2006

Purpose : Bacteremia is one of the major concerns in the treatment of pediatric cancer patients. This study was to determine the etiologic agents and the pattern of antibiotic susceptibilities in a single tertiary medical center. Methods : We retrospectively reviewed the medical records of the cases of bacteremia in pediatric cancer patients from 1998 to 2005 in Keimyung University Dongsan Medical Center. Results : There were 62 cases of bacteremia from 44 patients. Gram-positive organisms(48.3%) were more common than gram-negative organisms(38.7%) or fungi(13%). Among gram-positive organisms, Staphylococcus epidermidis was the most common etiologic agent(63.3%), followed by Staphylococcus aureus(16.7%), ${\alpha}$-hemolytic Streptococcus(16.7%), and Streptococcus mitis(3.3%). Among gram-negative organisms, Alcaligenes xylosoxidans was the most common agent(41.7%) and the other organisms were Klebsiella pneumoniae(20.8%), Stenotrophomonas maltophilia(12.5%), Acinetobacter baumanii(8.2%), etc. In febrile neutropenic patients, however, K. pneumoniae was the most common cause of gram-negative bacteremia. All of the isolated K. pneumoniae in our center produced extended-spectrum beta-lactamase and were related with high mortality. S. aureus, S. epidermidis, and Streptococcus species were all susceptible to vancomycin and teicoplanin. Most staphylococci were resistant to penicillin and oxacillin. Most of the gram-negative organisms were susceptible to imipenem. Conclusion : Gram-positive organisms were more commonly isolated than gram-negative organisms in pediatric cancer patients like other studies. We could obtained valuable information on the choice of proper antibiotics in our institution. Further studies will be needed to explain the prevalence of A. xylosoxidans in our center.

• Pediatric Infection and Vaccine
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• v.17 no.1
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• pp.36-48
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• 2010

Purpose : In children on anticancer chemotherapy, bloodstream infections (BSIs) are a major cause of morbidity and mortality. We investigated febrile episodes and bloodstream infections in pediatric cancer patients to guide proper selection of empiric antibiotics for febrile pediatric hemato-oncologic patients. Methods : All febrile episodes treated in the division of hematology-oncology, the department of pediatrics, Hanyang University Hospital, between July 2005 and June 2008 were reviewed. Episodes with and without bloodstream infections were compared. Results : Forty cases (18.9%, 25 patients) of BSI occurred in 212 febrile episodes (63 patients). Thirty-seven cases (23.6%, 22 patients) of BSI occurred in 157 febrile episodes with neutropenia (54 patients). Microorganisms identified in BSI corresponded to 23 gram-positive bacteria (51.2%), 20 gram-negative bacteria (44.5%), and 2 fungi (4.4%). Rates of BSI between those who had received umbilical cord blood transplantation and those who had received transplantation from other source were significantly different (55.0% vs. 7.7%, P =0.001). No differences in mortality rate were observed among organisms in BSI patients. For febrile episodes the rate of BSI was higher among those with Chemoport than those with Hickman catheter (P =0.029) and gram-positive pathogens were more likely to be associated with Chemoport (P =0.001). Conclusion : The study showed the rate of BSI, distribution of pathogens with regard to neutropenia, transplantation, central venous catheters, and antimicrobial susceptibility of pathogens in order to help guide in the choice of optimal empiric antibiotics in pediatric febrile neutropenic hemato-oncologic patients.

• Pediatric Infection and Vaccine
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• v.12 no.1
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• pp.67-74
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• 2005

Purpose : The incidence of mortality associated with respiratory difficulties is decreasing nowadays contributed to the development of neonatology. However, complications associated with mechanical ventilator are increasing. This study is to determine clinical manifestations, diagnositc availability of the endotracheal tip culture in patients with Ventilator-Associated Pneumonia(VAP) in neonatal intensive care unit(NICU). Methods : A retrospective analysis of 50 neonates who were admitted to the NICU of Kangnam Sacred Heart Hospital and had given mechanical ventilator from 1 January 2000 to 30 June 2003. VAP group defined as neonates who had pneumonia with mechanical ventilation longer than 48 hours. They were classified into VAP group(n=13) and control group (n=37) and the prevalence, microorganisms cultured from the endotracheal tube tip and risk factors were investigated. Results : The prevalence of VAP was 26.0%(n=13) and the most dominant microorganism cultured in our NICU was methicillin-resistant coagulase negative staphylococcus(MR-CNS) in 4 cases. Other microorganisms were Pseudomonas, Enterobacter, methicillin-resistant Staphylococcus aureus(MRSA) and Klebsiella. Gestational age, birth weight, Apgar score, respiratory distress syndrome, retinopathy of prematurity, bronchopulmonary dysplasia, sepsis, renal failure, pulmonary hemorrhage, pneumothorax were not different significantly between two groups except intraventricular hemorrhage(P<0.001) and patent ductus arteriosus(P<0.05). Duration of hospital stay and mortality rate were also not different significantly. Conclusion : VAP occurred at a significant rate among mechanically ventilated NICU patients. Despite of limitation of encotracheal tip culture, the most common microorganism was MR-CNS. We should be aware of occurrence of VAP in NICU neonate who were with mechanical ventilator and should treat with great care.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.639-643
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• 2002

Water quality, bacterial phase and fish growth rate were analyzed in the process of artificial seed production of flounder (Paralichtys oliraceus) larvae to investigate the water quality in rearing tank using Ultra Filtration System (UES). Sand Filtration System (SFS) and Ultra Filtration System (Ins) were set up in the experimental group. For the analysis of water quality, pH, salinity, DO, SS, COD, $NH_{4}^{+},\;NO_{2}^{-},\;NO^-,\;DIN$ (dissolved inorganic nitrogen) and DU (dissolved inorganic phosphate) were measured. There was no data difference between SFS group and UES group in most analysis items, but the UEs group showed low salinity and low 55 values, such that salinity was $33.5\%_{\circ}$ in SES group and $30.2\%_{\circ}$ in WS group and 55 was 15.5 mL/L in SES group and 7.0 mL/L for UPS group. For changes in bacterial phase and TBC (Total Bacterial Counts), in SES group, 6$\times$10^{5}CFU/mL in seawater decreased to the ratio of about 116, and TBC, Genus Vibrio and bacteria in the Genus Acinetobacter and Genus Micrococcus sharply increased after nine days, while stable bacterial phase was maintained low in UES group during the experiment except for Genus Ajteromonas. In the growth of the larvae, fish length was 17.0 mm (SGR 14.0) in the SES group and 18.8 mm (SGR 14.3) in the UFS group. It is concluded that when water is supplied for artificial seed production with WS, stabilization of water quality condition and inhibition of bacterial multiplication are possible. When production environment becomes stable, stable growth of fish becomes possible by reduction of environmental stress.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.135-142
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• 2011

Purpose : Hospital associated infection (HAI) caused by multidrug-resistant (MDR) microorganisms has been recognized as an important issue in the world, especially in critically ill patients such as the patients admitted in the intensive care unit. There are fewer papers about MDR-HAI in pediatric patients compared to adult patients. In this study, we investigated the incidence and associated factors of MDR-HAI in children admitted to the intensive care unit (ICU) of a university hospital. Methods : We retrospectively evaluated 135 children who were admitted in ICU for at least 3 days between January 2009 and December 2010. HAI cases were divided into MDR-HAI group and non-MDR-HAI group. Clinical characteristics and various associated factors were compared between those groups. Results : In 39 patients, 45 cases of ICU-related HAI were developed. ICU-related HAI incidence was 47.7 per 1000 patientdays. Thirty-six cases (80.0%) were MDR-HAI. Acinetobacter baumannii was isolated more commonly in MDR-HAI group. And the followings were found more frequently in MDR-HAI group than non-MDR-HAI group: medical condition as an indication for ICU admission, mechanical ventilation, urinary catheterization and previous use of broad-spectrum antibiotics. Among the risk factors, previous use of broad-spectrum antibiotics was the independent risk factor for MDR-HAI. Conclusion : ICU-related HAI incidence was higher than previously reported. Previous use of broad-spectrum antibiotics was the independent risk factor for MDR-HAI. To investigate the characteristics of MDR-HAI in children admitted in ICU, further studies with a larger sample size over a longer period of time are warranted.