• Asian Pacific Journal of Cancer Prevention
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• v.15 no.14
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• pp.5787-5791
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• 2014

Background: With increasing survival periods and diversification of treatment methods, treatment of critically ill cancer patients has become an important factor influencing patient prognosis. Patients with cancer are at high risk of infections and subsequent complications. This study investigated the incidence and factors contributing to the development of ventilator-associated pneumonia (VAP). Materials and Methods: This retrospective study investigated the incidence of VAP and factors leading to infection in patients admitted to the intensive care unit (ICU) of a cancer center from January 1, 2012 to December 31, 2013. Results: The incidence of VAP was 2.13 cases per 1,000 days of intubation, and 13 of 288 patients (4.5%) developed VAP. Lung cancer was the most common cancer associated with VAP (N=7, 53.9%), and longer hospital stays and intubation were associated with increased VAP incidence. In the group using a "ventilator bundle," the incidence was 1.14 cases per 1,000 days compared to 2.89 cases per 1,000 days without its use; however, this difference was not statistically significant (p=0.158). Age (${\geq}65$, OR=5.56, 95% confidence interval [CI]=1.29-23.95), surgery (OR=3.78, 95%CI=1.05-13.78), and tracheotomy (OR=4.46, 95%CI=1.00-19.85) were significant VAP risk factors. The most common causative organisms were methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (N=4, 30.8% each), followed by Acinetobacter baumannii and Candida albicans (N=2, 15.4% each). Conclusions: The incidence of pneumonia among critically ill cancer patients is highest in those with lung cancer, but lower than among non-cancer patients. The length of hospital stay and time on mechanical ventilation are important risk factors for development of VAP. Although not statistically significant, "ventilator bundle" care is an effective intervention that delays or reduces incidence of VAP. Major risk factors for VAP include age (${\geq}65$ years), surgery, and tracheostomy, while fungi, gram-negative bacteria, and multidrug-resistant organisms were identified as the major causative pathogens of VAP in this study.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.626-633
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• 2023

Vibrio spp. are aquatic bacteria that are ubiquitous in warm estuarine and marine environments. Especially, V. vulnificus and V. cholerae are currently known to cause potentially fatal infections in humans. This study investigated the distribution and antibiotic resistance of V. vulnificus and V. cholerae isolated from coastal areas of Gyeongsangnam-do in 2022. A total of 252 samples of water, shellfish and coastal sediment were collected from 7 locations along the coast, and 124 samples of fishery products were collected from markets. Among the 252 samples, forty-four V. vulnificus (11.7%) and fourteen V. cholerae non-O1/non-O139 (3.7%), none of which carried the ctx gene, were isolated. Out of the 124 samples, 6 (4.8%) tested positive for V. vulnificus and V. cholerae was not detected. The isolation rates of V. vulnificus and V. cholerae showed a significant correlation with environmental factors such as seawater temperature and salinity. In an antibiotic resistance test, V. vulnificus was susceptible to amikacin, gentamicin, imipenem trimethoprim/sulfamethoxazole, and ciprofloxacin, but resistant to cefoxitin (100.0%), followed by tetracycline (9.1%). Multidrug resistance was also observed. Continuous monitoring of Vibrio pathogens with water temperature and salinity is expected to help reduce the outbreaks, and rational use of antibiotic agents is needed to prevent the accession of antibiotic-resistant microorganisms in aquatic ecosystems.

• Journal of Microbiology and Biotechnology
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• v.34 no.8
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• pp.1718-1726
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• 2024

Development of novel antibacterial agents is imperative due to the increasing threat of antibiotic-resistant pathogens. This study aimed to develop the enhanced antibacterial activity and in-vivo efficacy of a novel truncated endolysin, CHAP^SAP26-161, derived from the endolysin Lys^SAP26, against multidrug-resistant bacteria. CHAP^SAP26-161 exhibited higher protein purification efficiency in E. coli and antibacterial activity than Lys^SAP26. Moreover, CHAP^SAP26-161 showed the higher lytic activity against A. baumannii with minimal bactericidal concentrations (MBCs) of 5-10 ㎍/ml, followed by Staphylococcus aureus with MBCs of 10-25 ㎍/ml. Interestingly, CHAP^SAP26-161 could lyse anaerobic bacteria, such as Clostridioides difficile, with MBCs of 25-50 ㎍/ml. At pH 4-8 and temperatures of 4℃-45℃, CHAP^SAP26-161 maintained antibacterial activity without remarkable difference. The lytic activity of CHAP^SAP26-161 was increased with Zn²⁺. In vivo tests demonstrated the therapeutic effects of CHAP^SAP26-161 in murine systemic A. baumannii infection model. In conclusion, CHAP^SAP26-161, a truncated endolysin that retains only the CHAP domain from Lys^SAP26, demonstrated enhanced protein purification efficiency and antibacterial activity compared to Lys^SAP26. It further displayed broad-spectrum antibacterial effects against S. aureus, A. baumannii, and C. difficile. Our in vitro and in-vivo results of CHAP^SAP26-161 highlights its promise as an innovative therapeutic option against those bacteria with multiple antibiotic resistance.

• Korean Journal of Plant Resources
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• v.28 no.1
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• pp.9-15
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• 2015

Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important hospital and community pathogens. At the same time, because of the difficulty in developing chemical synthetic drugs and because of their side-effects, scientists are making more efforts to search for new drugs from plant resources to combat clinical multidrug-resistant microbial infections. Cinnamomum camphora (C. camphora) is a plant of family Lauraceae, and grown Jeju island in South Korea that are used as a drug to treat neurasthenia, epilepsy, cystitis, pyelonephritis, digitalis, cancer, and diabetes mellitus in folk remedies. In this study, antibacterial activites of 80% ethanol extract of C. camphora leaves (CCE) were investigated in combination with antibiotics against clinical isolates of MRSA. The results showed that CCE was determined with MIC and MBC values ranging from 156 to 313 and 313 to $625{\mu}g/ml$, oxacillin from 128 to 256 and 128 to $512{\mu}g/ml$, ampicillin from 4 to 64 and 8 to $128{\mu}g/ml$. The combination of CCE with oxacillin or/and ampicillin were synergistic effect against MRSA 1, 6, 7, 8, 10, 11, 12, 13, and 15/ MRSA 1, 2, 6, and 7.

• Microbiology and Biotechnology Letters
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• v.46 no.2
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• pp.162-170
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• 2018

Non-typhoidal Salmonella is one of the main pathogens causing food-borne illness in humans, with up to 20% of cases resulting from consumption of pork products. Over the gastroenteritis signs, multidrug resistant Salmonella has arisen. In this study, pan-susceptible phenotypic strains of Salmonella enterica serotype Weltevreden recovered from pig production chain in Chiang Mai, Thailand during 2012-2014 were chosen for analysis. The aim of this study was to use whole genome sequencing (WGS) data with an emphasis on antimicrobial resistance gene investigation to assess their pathogenic potential and genetic diversity determination based on whole genome Multilocus Sequence Typing (wgMLST) to expand epidemiological knowledge and to provide additional guidance for disease control. Analyis using ResFinder 3.0 for WGS database tracing found that one of pan-susceptible phenotypic strain carried five classes of resistance genes: aminoglycoside, beta-lactam, phenicol, sulfonamide, and tetracycline associated genes. Twenty four and 36 loci differences were detected by core genome Multilocus Sequence Typing (cgMLST) and pan genome Multilocus Sequence Typing (pgMLST), respectively, in two matching strains (44/13 vs A543057 and A543056 vs 204/13) initially assigned by conventional MLST and Pulsed-field Gel Electrophoresis (PFGE). One hundread percent discriminant ability can be achieved using the wgMLST technique. WGS is currently the ultimate molecular technique for various in-depth studies. As the findings stated above, a new of "gold standard typing method era" for routine works in genome study is being set.

• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.24-32
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• 2003

Purpose : Nosocomial infection with Staphylococcus aureus, especially methicillin resistant S. aureus, has become a serious concern in the neonatal intensive care unit. The aim of this study is to investigate the virulence factors, and the relationship between the antibiotic resistance and the associated genes of Staphylococcus aureus isolated from nasal cavity of neonates. Methods : Fifty one isolates of S. aureus were obtained from nasal swab taken in 28 neonates in the NICU and nursery of Pusan National University Hospital between February and May, 2001. They were tested in regard to antibiotic susceptibility, coagulase test and typing, plasmid DNA profile, as well as reactivity to enterotoxin A-E(sea, seb, sec, sed, see) genes and toxic shock syndrome toxin-1(tst) gene by polymerase chain reaction(PCR). Associated genes such as mecA, mecR1, mecI, and femA were also determined by PCR. The origin of MRSA strains was assessed using DNA fingerprinting by arbitrarily-primed polymerase chain reaction(AP-PCR). Results : Twenty three(45.1%) and six(11.8%) isolates were resistant to oxacillin and vancomycin respectively. Multidrug resistance to three or more of the antibiotics tested was observed in 51.0% of the isolates. Forty two isolates were coagulase positive and twenty two isolates had mecA gene. Sixteen isolates had both mecA and femA genes and had type I-III plasmids. 64.7% of isolates carried sec gene, and 80.4% carried tst gene. DNA fingerprinting by AP-PCR for 12 MRSA strains showed 10 distinct patterns, suggesting different origins. Conclusion : We confirmed that the prevalence of nasal carriage of S. aureus and the incidence of antimicrobial-resistant S. aureus, especially vancomycin resistance, is very high in neonates who were admitted in NICU and nursery. It is possible that these pathogens are responsible for serious nosocomial infections in neonates. The need for improved surveillance and continuous control of pathogens is emphasized.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.3
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• pp.256-262
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• 2017

Essential oil from herb is known to exert pharmacological effects on the human body. In this study we investigated the antibacterial activity of 4 essential oils (teetree, rosemary, melisa, and lavender), as well as the blended mixture oil of teetree, rosemary, and melisa (TRM) on three bacteria, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Antibacterial analysis was performed using the standard disk diffusion method, and minimum inhibition concentration was determined by the broth microdilution method with different concentrations of essential oils (0.5, 1, 2 and 3 mg/mL). After incubation at $37^{\circ}C$ for 24 h, the antibacterial activity was assessed by measuring the zone of growth inhibition surrounding the disks. Herb oil with the inhibition zones showed varied values ranging from6 to 25 mm. However, the components of herb oil of TRM are as highly active as the teetree oil against pathogens, generating large inhibition zones for both gram negative and positive bacteria (13~22 mm and 8 mm inhibition zones). In the analysis for MIC, TRM showed growth-inhibitory effects at 0.0625% for S. aureus and E. coli, and 1.25% for P. aeruginosa. This result demonstrated that the anti-microbial activity of TRM was greater than a single herb oil, including oxacillin, rosemary, and teetrea. As a single herb oil, both rosemary and teetrea also had an anti-microbial effect by itself, and we can expect that the blended oil mixture may exert a synergistic effect against multidrug resistant bacteria, suggesting its future application in natural preservative agents for health food and cosmetics.

• Journal of Life Science
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• v.25 no.7
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• pp.833-838
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• 2015

Multidrug-resistant super bacterial, fungal, viral, and parasitic infections are major health threaten pathogens. However, to overcome the present healthcare situation, among the leading alternatives to current drugs are antimicrobial peptides (AMPs), which are abundantly produced via various species in nature. AMPs, small host defense proteins, are in charge of the innate immunity for the protection of multicellular organisms such as fish, amphibian, reptile, plants and animals from infection. The number of AMPs identified per year has increased steadily since the 1980s. Over 2,000 natural AMPs from bacteria, protozoa, fungi, plants, and animals have been listed into the antimicrobial peptide database (APD). The majority of these AMPs (>86%) possess 11–50 amino acids with a net charge from 0 to +7 and hydrophobic percentages between 31–70%. This report classified AMP into several categories including biological source, biological functions, peptide properties, covalent bonding pattern, and 3D structure. AMP functions not only antimicrobial activity but facilitates cell biological activity such as chemotatic activity. In addition, fibroblastic reticular cell (FRC) originated from mouse lymph node stroma induced the expression of AMP in inflammatory condition. AMP induced from FRC contained whey acidic protein (WAP) domain. It suggests that the classification of AMP will be done by protein domain.

• Tuberculosis and Respiratory Diseases
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• v.84 no.4
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• pp.317-325
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• 2021

Background: Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are significant public health issues in the world, but the epidemiological data pertaining to HAP/VAP is limited in Korea. The objective of this study was to investigate the characteristics, management, and clinical outcomes of HAP/VAP in Korea. Methods: This study is a multicenter retrospective cohort study. In total, 206,372 adult patients, who were hospitalized at one of the 13 participating tertiary hospitals in Korea, were screened for eligibility during the six-month study period. Among them, we included patients who were diagnosed with HAP/VAP based on the Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) definition for HAP/VAP. Results: Using the IDSA/ATS diagnostic criteria, 526 patients were identified as HAP/VAP patients. Among them, 27.9% were diagnosed at the intensive care unit (ICU). The cohort of patients had a median age of 71.0 (range from 62.0 to 79.0) years. Most of the patients had a high risk of aspiration (63.3%). The pathogen involved was identified in 211 patients (40.1%). Furthermore, multidrug resistant (MDR) pathogens were isolated in 138 patients; the most common MDR pathogen was Acinetobacter baumannii. During hospitalization, 107 patients with HAP (28.2%) had to be admitted to the ICU for additional care. The hospital mortality rate was 28.1% in the cohort of this study. Among the 378 patients who survived, 54.2% were discharged and sent back home, while 45.8% were transferred to other hospitals or facilities. Conclusion: This study found that the prevalence of HAP/VAP in adult hospitalized patients in Korea was 2.54/1,000 patients. In tertiary hospitals in Korea, patients with HAP/VAP were elderly and had a risk of aspiration, so they were often referred to step-down centers.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.2
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• pp.155-163
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• 2019

During the time period from 2010 to 2017, out of 162,551 blood specimens, 11,233 (6.9%) specimens were positive for culture and 11,865 strains were cultured. Among the isolates, 47.8% were Gram positive cocci, 38.8% were Gram negative rods, 4.2% were Gram positive bacilli, 6.8% were fungi and 2.3% were anaerobes. When the culture results were compared according to gender, 55.0% (2,732/4,969) of the isolates were found in males and 45.0% (2,237/4,969) were isolated in females. In addition, when categorized according to age group, people in their 70s were the most separated by 28.7% (1,426/4,969) and this showed a great difference from 1.2% (62/4,969) of people in their teens. MRSA decreased significantly from 66.7% in 2016 to 46.8% in 2017. The vancomycin resistance rate of E. faecium was 35.0% (48/137). The ESBL positive rate of E. coli in intestinal bacteria was increased from 17.2% in 2010 to 28.8% in 2017, but the positive rate decreased for K. pneumoniae. 11.8% (14/119) of multidrug-resistant P. aeruginosa (MDRPA) of P. aeruginosa and 64.3% (161/252) of MDRAB of A. baumannii showed high resistance. Because the microbial susceptibility and antimicrobial susceptibility patterns of the blood specimens isolated from all the blood specimens differ according to the time period, region and patients, periodic analyses of different pathogens and understanding the changes in the degree of susceptibility to antimicrobial susceptibility have been conducted in hospitals.