Among 213 Pseudomonas aeruginosa isolates collected from 10 South Korean hospitals, 57 isolates (26.8%) were carbapenem-resistant. All but three of the isolates had a relevant decrease of oprD ...expression. However, decreased oprD expression was also detected in five of ten carbapenem-susceptible isolates. Outer membrane protein analysis confirmed porin loss in carbapenem-resistant P. aeruginosa isolates. Based on the mutations of oprD gene sequences, carbapenem-resistant P. aeruginosa isolates could be classified into five oprD mutational groups. However, there was no difference of OprD expression or carbapenem minimum inhibitory concentrations among the five mutational groups. Among the 57 carbapenem-resistant P. aeruginosa isolates, 41 (71.9%) overexpressed efflux systems or ampC. MexAB–OprM and AmpC overexpression (56.1% and 47.4%, respectively) was prevalent and was significantly associated with carbapenem resistance. However, no synergistic effect of efflux systems and AmpC on carbapenem resistance was evident. In conclusion, combination of several mutation-driven mechanisms leading to OprD inactivation and overexpression of efflux systems was the main carbapenem resistance mechanism, but acquisition of a transferable resistance determinant such as metallo-β-lactamase could be problematic in clinical settings in South Korea.
A fully water-based patterning method for polymer semiconductors was developed and utilized to realize high-precision lateral patterning of various polymers. Water-borne polymer colloids, wherein ...hydrophobic polymers are dispersed in water with the assistance of surfactant molecules, possess a hydrophilic surface when printed onto a substrate. When this surface is exposed to a washing molecule, the surface of the polymer film recovers its original hydrophobic nature. Such surfactant-induced solubility control (SISC) enables environmentally benign, water-processed, and high-precision patterning of various polymer semiconductors with totally different solubilities, so that fully water-processed polymer organic image sensors (OISs) can be realized. B-/G-/R-selective photodiodes with a pixel size of 100 μm × 100 μm were fabricated and patterned by this water-based SISC method, leading to not only high average specific detectivity values (over 1012 Jones) but also narrow pixel-to-pixel deviation. Thanks to the superiority of the SISC method, we demonstrate the image capturing ability of OISs without B-/G-/R-color filters, from a fully water-based fabrication process.
This study aimed to identify the species of
complex (ECC) isolates and compare the genotype, antibiotic resistance, and virulence among them. A total of 183 ECC isolates were collected from patients ...in eight hospitals in South Korea. Based on partial sequences of
and phylogenetic analysis, all ECC isolates were identified as nine species and six subspecies.
was the predominant species (47.0%), followed by
,
,
, and
. Multilocus sequence typing analysis revealed that dissemination was not limited to a few clones, but
subsp.
,
subsp.
, and
formed large clonal complexes. Antibiotic resistance rates were different between the ECC species. In particular,
,
,
, and
isolates were highly resistant to colistin, whereas most
and
isolates were susceptible to colistin. Virulence was evaluated through serum bactericidal assay and the
larvae infection model. Consistency in the results between the serum resistance and the
larvae infection assay was observed. Serum bactericidal assay showed that
,
, and
were significantly more virulent than
and
. In this study, we identified the predominant ECC species in South Korea and observed the differences in antibiotic resistance and virulence between the species. Our findings suggest that correct species identification, as well as continuous monitoring is crucial in clinical settings.
Abstract
The contaminated healthcare environment plays an important role in the spread of multidrug-resistant organisms (MDROs) and
Clostridioides difficile.
This study aimed to evaluate the ...antimicrobial effects of ozone generated by a dielectric barrier discharge (DBD) plasma reactor on various materials that were contaminated by vancomycin-resistant
Enterococcus faecium
(VRE), carbapenem-resistant
Klebsiella pneumoniae
(CRE), carbapenem-
resistant Pseudomonas aeruginosa
(CRPA), carbapenem-resistant
Acinetobacter baumannii
(CRAB) and
C. difficile
spores. Various materials contaminated by VRE, CRE, CRPA, CRAB and
C. difficile
spores were treated with different ozone concentrations and exposure times. Atomic force microscopy (AFM) demonstrated bacterial surface modifications following ozone treatment. When an ozone dosage of 500 ppm for 15 min was applied to VRE and CRAB, about 2 or more log
10
reduction was observed in stainless steel, fabric and wood, and a 1–2 log
10
reduction in glass and plastic. Spores of
C. difficile
were more resistant to ozone than were all other tested organisms. On AFM, the bacterial cells, following ozone treatment, were swollen and distorted. The ozone generated by the DBD plasma reactor provided a simple and valuable decontamination tool for the MDROs and
C. difficile
spores, which are known as common pathogens in healthcare-associated infections.
Nonalcoholic steatohepatitis (NASH) is considered as a progressive form of nonalcoholic fatty liver disease (NAFLD). To distinguish NASH from nonalcoholic fatty liver (NAFL), we evaluated the ...diagnostic value of circulating miRNAs. Small RNA sequencing was performed on 12 NAFL patients and 12 NASH patients, and the miRNA expression was compared. After selecting miRNAs for the diagnosis of NASH, we analyzed the diagnostic accuracy of each miRNA and the combination of miRNAs. External validation was performed using quantitative reverse transcription PCR. Among the 2,588 miRNAs, 26 miRNAs significantly increased in the NASH group than in the NAFL group. Among the 26 elevated miRNAs in the NASH group, 8 miRNAs were selected, and in silico analysis was performed. Only four miRNAs (miR-21-5p, miR-151a-3p, miR-192-5p, and miR-4449) showed significant area under the receiver operating characteristic curve (AUC) values for NASH diagnosis. The combination of the four miRNAs showed satisfactory diagnostic accuracy for NASH (AUC 0.875; 95% CI 0.676-0.973). External validation revealed similar diagnostic accuracy for NASH (AUC 0.874; 95% CI 0.724-0.960). NASH represents significantly distinct miRNA expression profile compared with NAFL. The combination of serum circulating miRNAs can be used as a novel biomarker for the NASH diagnosis in NAFLD.
Gaining an insight into the mechanism underlying antimicrobial-resistance development in
is crucial for identifying effective antimicrobials. We isolated
sequence type 72 from a patient in whom the
...infection was highly resistant to various antibiotics and lysostaphin, but no known resistance mechanisms could explain the mechanism of lysostaphin resistance. Genome-sequencing followed by subtractive and functional genomics revealed that serine hydroxymethyltransferase (
or
gene) plays a key role in lysostaphin resistance. Serine hydroxymethyltransferase (SHMT) is indispensable for the one-carbon metabolism of serine/glycine interconversion and is linked to folate metabolism. Functional studies revealed the involvement of SHMT in lysostaphin resistance, as Δ
was susceptible to the lysostaphin, while complementation of the knockout expressing
restored resistance against lysostaphin. In addition, the Δ
showed reduced virulence under
(mammalian cell lines infection) and
(wax-worm infection) models. The SHMT inhibitor, serine hydroxymethyltransferase inhibitor 1 (SHIN1), protected the 50% of the wax-worm infected with wild type
. These results suggest SHMT is relevant to the extreme susceptibility to lysostaphin and the host immune system. Thus, the current study established that SHMT plays a key role in lysostaphin resistance development and in determining the virulence potential of multiple drug-resistant
.
•NDM-1-producing Acinetobacter seifertii was identified in Korea.•Whole plasmid sequences were similar to several plasmids from A. nosocomialis and A. cumulans.•No fitness cost was found in the ...plasmid-transconjugated A. seifertii strain.
The aim of this study was to characterize an NDM-1-producing Acinetobacter seifertii isolates from a patient in South Korea.
Antibiotic susceptibility testing and genotyping using multigene sequencing were performed and whole plasmid sequences were determined.
The genotype of A. seifertii was ST1899 and was resistant to ceftazidime, trimethoprim–sulfamethoxazole, and piperacillin–tazobactam, in addition to carbapenem. blaNDM-1 was surrounded by the ISAba125 insertion sequence within the structure of Tn125 in the 47 kb-sized plasmid. The plasmid exhibited a structure similar to that of other plasmids of diverse Acinetobacter sp. found worldwide. Transconjugation and the growth curve indicated that the plasmid was adapted to A. seifertii rather than other closely related Acinetobacter sp.
Acquisition of carbapenem resistance by horizontal transfer of the blaNDM-1-carrying plasmid from another Acinetobacter species was found with no growth defect.
The present study was undertaken to find novel genes associated with colistin resistance in Klebsiella pneumoniae. Five colistin-resistant mutants were derived from four colistin-susceptible parental ...K. pneumoniae strains belonging to different clones. Whole-genome sequencing was performed for the nine K. pneumoniae strains to screen altered candidate genes. Expression levels of genes with amino acid alterations in derivative strains were determined using quantitative real-time Polymerase chain reaction (PCR). Colistin susceptibility was examined in a parental strain complemented with altered candidate genes. Overall, 13 genetic alterations were identified in five pairs of isogenic K. pneumoniae strains. Genetic alterations related to KP1_3468, including the insertion of an IS5-like element in an intergenic or coding region and amino acid substitutions, were identified in three separate derivative strains. Amino acid substitutions and deletion of PhoQ were determined in one derivative strain. With inactivation of CrrA and substituted CrrB, amino acid substitutions and deletion were identified in a repressor of galETK operon (KP1_0061) and hypothetical protein (KP1_3620), respectively. Decreased colistin susceptibility was observed in a parental strain complemented with KP1-0061, but not a KP1-3620 gene. This study demonstrated diverse genetic paths to colistin resistance in K. pneumoniae. Our results suggest that a repressor of galETK operon may play an important role in colistin resistance in K. pneumoniae.
Molecular and virulence characteristics of CTX-M-producing and non-extended-spectrum-β-lactamase (non-ESBL)-producing Klebsiella pneumoniae isolates were compared. Lack of shared characteristics ...between the two groups suggested that most CTX-M-producing K. pneumoniae isolates in South Korea did not occur by transfer of blaCTX-M into susceptible strains. Conjugation assays confirmed that the plasmid with the blaCTX-M-15 gene confers virulence as well as antimicrobial resistance, suggesting that a CTX-M-15-producing clone such as ST11 may have a selective advantage even without antibiotic pressure.
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