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1.
Yonsei Medical Journal ; : 241-251, 2022.
Article in English | WPRIM | ID: wpr-927157

ABSTRACT

Purpose@#Here, we aimed to elucidate the differences in microbiota composition between patients with gout and those with asymptomatic hyperuricemia (asHU) and determine the effect of uric acid-lowering therapy (ULT) on the gut microbiome. @*Materials and Methods@#Stool samples from patients with asHU (n=8) and three groups of gout patients, i.e., acute gout patients before ULT (0ULT, n=14), the same acute gout patients after 30-day ULT (30ULT, n=9), and chronic gout patients after ≥6-month ULT (cULT, n=18) were collected and analyzed using 16S rRNA gene-based pyrosequencing. The composition of microbial taxonomy and communities, species diversity, and relationships among microbial communities were elucidated by bioinformatic analysis. @*Results@#Gout patients showed less diverse gut microbiota than asHU patients. The microbiota of the asHU group exhibited a higher Firmicutes-to-Bacteroidetes (F/B) ratio and lower Prevotella-to-Bacteroides (P/B) ratio than the gout group; significantly, the F/B ratio increased in gout patients after ULT. Moreover, a balanced enterotype populated asHU patients compared to gout patients. Notably, the gut microbiota in asHU patients had a higher proportion of taxa with potentially anti-inflammatory effects compared to the gut microbiota in gout patients. @*Conclusion@#We found that microbial composition differs between asHU and gout patients. The differential gut microbiota in asHU patients may protect against gout development, whereas that in gout patients may have a role in gout provocation. ULT in gout patients altered the gut microbiota, and may help alleviate gout pathology and mitigate gout progression.

2.
Article in English | WPRIM | ID: wpr-925412

ABSTRACT

Background@#There has been a marked increase in the mortality rate associated with Clostridioides difficile infection (CDI) globally since 2003, with the emergence of binary toxinproducing ribotype 027 strains. However, the molecular epidemiology of C. difficile shows regional differences and ribotype 027 is not common in Korea. In this study, the risk factors for severe CDI were evaluated, while considering the region-specific molecular epidemiology. @*Methods@#A retrospective case-control study was performed. Cases (n = 149) included patients with severe CDI or severe complicated CDI. Controls (n = 155) consisted of patients with nonsevere CDI. @*Results@#Advanced age (odds ratio [OR] = 1.017, P = 0.0358), a history of chemotherapy (OR = 2.695, P = 0.0464), and ribotype 002 (OR = 3.406, P = 0.0231) were statistically significant factors associated with severe CDI in a multivariate analysis. @*Conclusion@#Ribotype 002 was found to be a significant risk factor for severe CDI in this study.Therefore, the surveillance of C. difficile ribotypes is recommended to monitor the spread of high-risk clones.

3.
Article in English | WPRIM | ID: wpr-874147

ABSTRACT

Procalcitonin (PCT) is a useful bacterial infection biomarker with the potential for guiding antibiotic therapy. We evaluated the concordance of three automated PCT immunoassays: Kryptor (BRAHMS GmbH, Hennigsdorf, Germany), Atellica IM 1600 (Siemens Healthcare Diagnostics, Munich, Germany), and Cobas e801 (Roche Diagnostics, Mannheim, Germany). In 119 serum samples with a PCT concentration < 5.00 μg/L, Kryptor (reference assay) was compared with the other two immunoassays by Spearman’s rank correlation, regression analysis, and concordance at two antibiotic stewardship medical decision points: 0.25 and 0.50 μg/L. The Atellica IM 1600 and Cobas e801 results showed high correlations with those of Kryptor, with correlation coefficient (ρ) values of 0.97 and 0.99, respectively. However, negative biases were observed in both immunoassays (slope/y-intercept: 0.75/–0.00 for Atellica IM 1600; 0.88/–0.01 for Cobas e801). Atellica IM 1600 and Cobas e801 demonstrated excellent concordance with Kryptor at both medical decision points, with linearly weighted κ values of 0.90 and 0.92, respectively, despite discrepancies, which were more prominent at the 0.25 μg/L medical decision point. Based on these biases and discrepancies, the alternate use of different PCT immunoassays in repeat examinations is inadvisable. Standardization is required before comparing the results of different PCT immunoassays.

4.
Article in English | WPRIM | ID: wpr-762460

ABSTRACT

BACKGROUND: Carbapenem-resistant K. pneumoniae 2297, isolated from a patient treated with tigecycline for pneumonia, developed tigecycline resistance, in contrast to carbapenem-resistant isolate 1215, which was collected four months prior to the 2297 isolate. Mechanisms underlying tigecycline resistance were elucidated for the clinical isolates. METHODS: The tigecycline minimum inhibitory concentration (MIC) was determined using the broth microdilution method, with or without phenylalanine-arginine β-naphthylamide (PABN), and whole-genome sequencing was carried out by single-molecule real-time sequencing. The expression levels of the genes acrA, oqxA, ramA, rarA, and rpoB were determined by reverse-transcription quantitative PCR. RESULTS: Both isolates presented identical antibiograms, except for tigecycline, which showed an MIC of 0.5 mg/L in 1215 and 2 mg/L in 2297. The addition of PABN to tigecycline-resistant 2297 caused a four-fold decrease in the tigecycline MIC to 0.5 mg/L, although acrA expression (encoding the AcrAB efflux pump) was upregulated by 2.5 fold and ramA expression (encoding the pump activator RamA) was upregulated by 1.4 fold. We identified a 6,096-bp fragment insertion flanking direct TATAT repeats that disrupted the romA gene located upstream of ramA in the chromosome of K. pneumoniae 2297; the insertion led the ramA gene promoter replacement resulting in stronger activation of the gene. CONCLUSIONS: The K. pneumoniae isolate developed tigecycline resistance during tigecycline treatment. It was related to the overexpression of the AcrAB resistance-nodulation-cell division efflux system due to promoter replacement.


Subject(s)
Humans , Klebsiella pneumoniae , Klebsiella , Methods , Microbial Sensitivity Tests , Pneumonia , Polymerase Chain Reaction , Rome
5.
Article | WPRIM | ID: wpr-830347

ABSTRACT

Background@#Ideal dose of the antimicrobials should be decided by considering their killing dynamics since sufficient elimination of the causative microorganisms is critical for proper antimicrobial treatment. In this study, the bactericidal activities of carbapenems by resistance mechanisms were assessed for carbapenem-resistant Pseudomonas aeruginosa. @*Methods@#Minimal inhibition concentrations (MICs) of carbapenems were determined by broth dilution method and the resistance mechanisms were identified by PCR and DNA sequencing. The expression levels of efflux pumps were determined by reverse transcriptase real-time PCR. Time-kill curves were plotted by time-course numeration of the viable cells grown under imipenem and meropenem at 1× and 4×MICs, respectively. @*Results@#One P. aeruginosa strain was susceptible, whereas three were resistant to carbapenems by defective OprD, efflux pump overproduction, and/or IMP-6 production.The susceptible strain had imipenem and meropenem MICs of 2 and 1 mg/L, respectively.The MICs were elevated by eight-fold by defective OprD, 16- and 32-fold by the pump overproduction, and four- and >64-fold by the combination of two determinants and the IMP-6 carbapenemase. While both the carbapenems showed time-dependent bactericidal activity to the susceptible isolate, either of the carbapenem-resistant determinants, such as decreased membrane permeability, carbapenemase production, or the defective OprD, presented concentration-dependent bacteriostatic activity. @*Conclusion@#Different killing dynamics of the carbapenems were observed depending on the resistance determinants, and the results would guide a proper treatment strategy for the patients using these drugs.

6.
Article | WPRIM | ID: wpr-830346

ABSTRACT

Background@#The prevalence of carbapenemase-producing Enterobacteriaceae (CPE), especially the KPC-2-producing Klebisella pneumoniae, is rapidly increasing and becoming a menace to global public health. This study aims to present the molecular epidemiology of the KPC-2-producing K. pneumoniae isolates emerged in a tertiary hospital in South Korea and describe its clinical significance. @*Methods@#This study included carbapenem-resistant K. pneumoniae isolates collected from a tertiary hospital from April to December in 2018. Antimicrobial susceptibility of K. pneumoniae isolates was tested using disk diffusion method. PCR and DNA sequence analyses were performed to identify the resistance genotype. In addition, the molecular epidemiology was investigated using pulsed-field gel electrophoresis (PFGE) and multilocus sequencing typing (MLST). @*Results@#Total 100 KPC-2-producing K. pneumoniae isolates were collected, which were mainly classified into two pulsotypes according to the XbaI restriction digestion pattern by PFGE analysis (pulsotype A, n = 31; pulsotype B, n = 63). The isolates exhibiting pulsotype A belonged to ST395 and the remaining isolates exhibiting pulsotype B were attributed to ST307 by MLST analysis. @*Conclusion@#This study investigated clinical information and molecular bacterial profiles for KPC-2-producing K. pneumoniae isolates. These findings indicate that the proper infection control activities are needed to prevent the spread of multidrug-resistant organisms such as CPE, which could cause high mortality in clinical field.

7.
Article in Korean | WPRIM | ID: wpr-816606

ABSTRACT

BACKGROUND: Acinetobacter baumannii infection is a significant health problem worldwide due to increased drug resistance. The limited antimicrobial alternatives for the treatment of severe infections by multidrug-resistant A. baumannii (MDRAB) make the search for other therapeutic options more urgent. Linalool, the major oil compound in Coriandrum sativum, was recently found to have high antibacterial activity against A. baumannii. The purpose of this study was to investigate the synergistic effect of linalool and colistin combinations against MDRAB and extensively drug-resistant A. baumannii (XDRAB).METHODS: A total of 51 strains of A. baumannii clinical isolates, consisting of 10 MDRAB and 41 XDRAB were tested. We determined the minimum inhibitory concentration (MIC) of linalool for the test strains using the broth microdilution method and searched for interactions using the time-kill assay.RESULTS: The time-kill assay showed that the linalool and colistin combination displayed a high rate of synergy (92.1%) (by synergy criteria 2), low rate of indifference (7.8%), and a high rate of bactericidal activity (74.5%) in the 51 clinical isolates of A. baumannii. The synergy rates for the linalool and colistin combination against MDRAB and XDRAB were 96% and 92.1%, respectively. No antagonism was observed for the linalool and colistin combination.CONCLUSION: The combination of linalool and colistin showed a high synergy rate, which may be beneficial for controlling MDRAB infections. Therefore, this combination is a good candidate for in vivo studies to assess its efficacy in the treatment of MDRAB infections.


Subject(s)
Acinetobacter baumannii , Acinetobacter , Colistin , Coriandrum , Drug Resistance , Methods , Microbial Sensitivity Tests
8.
Article in English | WPRIM | ID: wpr-785392

ABSTRACT

There is an urgent need for accurate and rapid diagnostic assays capable of identifying carbapenemase-producing Enterobacteriaceae (CPE). We assessed the performance of the RESIST-4 O.K.N.V. (OKNV) assay (Coris BioConcept, Gembloux, Belgium) for the identification of oxacillinase (OXA)-48-like-, Klebsiella pneumoniae carbapenemase (KPC)-, New Delhi metallo-β-lactamase (NDM)-, and Verona integron-encoded metallo-β-lactamase (VIM)-producing Enterobacteriaceae grown on sheep blood agar (SBA) and the CHROMagar KPC medium. Sixty-five carbapenem-resistant Enterobacteriaceae (CRE) isolates with characterized carbapenemase content were used to evaluate the OKNV assay. The assay correctly identified all 30 isolates that produced one of the four targeted carbapenemase families. Additionally, it correctly identified 15 isolates that co-produced KPC and NDM, VIM and NDM or OXA-48-like and NDM, but failed to identify an NDM-1 and OXA-232 co-producing Klebsiella pneumoniae isolate. All 16 non-carbapenemase-producing CRE and four CPE isolates exhibited negative results, and no cross-reaction was observed. Overall, the sensitivity and specificity of the assay were 97.8% and 100%, respectively. The OKNV assay is an accurate and rapid assay for identifying OXA-48-like, KPC, NDM, and VIM carbapenemases produced by Enterobacteriaceae isolates cultured on both SBA and the CHROMagar KPC media in the clinical microbiology laboratory.


Subject(s)
Agar , Enterobacteriaceae , Humans , Klebsiella pneumoniae , Sensitivity and Specificity , Sheep
9.
Article in English | WPRIM | ID: wpr-762441

ABSTRACT

BACKGROUND: Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea. METHODS: We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern. RESULTS: The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively. CONCLUSIONS: There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.


Subject(s)
Cefotaxime , Humans , Immunization Programs , Korea , Levofloxacin , Multiplex Polymerase Chain Reaction , Penicillins , Pneumococcal Vaccines , Pneumonia , Serogroup , Streptococcus pneumoniae , Streptococcus , Vaccines
10.
Article in Korean | WPRIM | ID: wpr-762288

ABSTRACT

BACKGROUND: Antimicrobial resistant continues to pose a threat to public health. Therefore, rapid and accurate antimicrobial susceptibility testing is very important. The objectives of this study were to evaluate the performance of the MicroScan system (Beckman Coulter, USA) with newly developed Korean Antimicrobial Susceptibility Testing Panels (KSCM panels) for antimicrobial susceptibility testing (AST) against clinical isolates in South Korea. METHODS: Three KSCM panels were designed in this study. For the performance evaluation, a total of 1,325 clinical isolates including 1,027 of Gram-negative bacilli and 298 Gram-positive cocci collected from eight general hospitals in South Korea were used. The results by KSCM panels were compared with those by conventional methods. RESULTS: By KSCM-1 panel for Gram-positive cocci, the rates of categorical agreement (CA) were >90% in all the antimicrobials tested in this study. The rates of major error (ME) were also 90%, ME rates <3%, and VME rates <1.5%. CONCLUSION: The newly developed three KSCM panels for MicroScan system (Beckman Coulter) showed excellent performance in AST against a large number of clinical isolates, and they are applicable to clinical microbiology laboratories.


Subject(s)
Ampicillin , Enterobacteriaceae , Gram-Positive Cocci , Hospitals, General , Hospitals, Teaching , Korea , Public Health , Tetracycline
11.
Article in Korean | WPRIM | ID: wpr-762287

ABSTRACT

BACKGROUND: Pulmonary infection with nontuberculous mycobacteria (NTM) is increasing in South Korea. Since treatment strategy differs by NTM species, accurate identification is necessary. In this study, using Mycobacterium pulmonary isolates recently recovered from a general hospital in Seoul, the prevalence of NTM isolates was investigated. METHODS: A total of 483 Mycobacterium pulmonary strains isolated between May and November 2018 from an 814-bed general hospital in South Korea were analyzed. Bacterial species were identified based on nucleotide sequences of the 16S–23S rDNA internal transcribed spacer and the rpoB gene. RESULTS: From a total of 1,209 pulmonary specimens from patients suspected to be infected with mycobacteria, 324 deduplicate strains were isolated, comprising 90 Mycobacterium tuberculosis and 229 NTM strains. Among the NTM isolates, 61.5% (n=144) were Mycobacterium avium complex (MAC), including 92 M. avium and 52 Mycobacterium intracellulare, while 8.1% (n=19) represented Mycobacterium abscessus, including 10 M. abscessus subsp. abscessus and 9 M. abscessus subsp. massiliense. In addition, 12 (5.1%) Mycobacterium lentiflavum, 12 (5.1%) Mycobacterium gordonae, 6 (2.6%) Mycobacterium kansasii, and 5 (2.1%) Mycobacterium fortuitum were identified. In addition, Mycobacterium mucogenicum (n=2), Mycobacterium septicum (n=1), Mycobacterium colombiens (n=1), Mycobacterium asiaticum (n=1), and Mycobacterium celatum (n=1) were identified. CONCLUSION: Among the recently recovered Mycobacterium pulmonary strains, more than half were identified as NTM, and MAC was the most prevalent NTM, followed by M. abcessuss.


Subject(s)
Base Sequence , DNA, Ribosomal , Hospitals, General , Humans , Korea , Mycobacterium , Mycobacterium avium Complex , Mycobacterium fortuitum , Mycobacterium kansasii , Mycobacterium tuberculosis , Nontuberculous Mycobacteria , Prevalence , Seoul , Tertiary Care Centers , Tertiary Healthcare
12.
Article in Korean | WPRIM | ID: wpr-762285

ABSTRACT

BACKGROUND: Fecal occult blood tests have been widely used to screen for colorectal cancer. SENTiFIT 270 (Sentinel diagnostics, Italy) is a fecal occult blood test with an immunochemical method that utilizes FOB Gold reagents. We evaluated the performance of SENTiFIT 270 using the FOB Gold reagent. In addition, FOB Gold was evaluated with the HITACHI 7180 (Hitachi Ltd., Japan). METHODS: The precision and linearity of the SENTiFIT 270 was evaluated in accordance with applicable Clinical and Laboratory Standard Institute guidelines. The comparison study between SENTiFIT 270-FOB Gold and the OC-Sensor (Eiken chemical Co., Japan) was performed using stool specimens. RESULTS: In the precision evaluation, the total precision of SENTiFIT 270-FOB Gold was 4.94% and 2.54% at high and low concentrations, respectively. The HITACHI 7180-FOB Gold had excellent precision of 4.60% and 2.09% at high and low concentrations, respectively. Linearity was also excellent for the SENTiFIT 270-FOB Gold and HITACHI 7180-FOB Gold at 0.9987 and 0.9986, respectively. The SENTITIF 270-FOB Gold showed excellent agreement with a kappa value of 0.830 and a concordance rate of 93.6%. The HITACHI 7180-FOB Gold showed high agreement with a kappa value of 0.832 and a concordance rate of 93.9%. CONCLUSION: The SENTiFIT 270-FOB Gold showed excellent performance in accuracy, linearity, and comparative inspection ability.


Subject(s)
Colonic Neoplasms , Colorectal Neoplasms , Indicators and Reagents , Methods , Occult Blood
13.
Article in English | WPRIM | ID: wpr-739143

ABSTRACT

BACKGROUND: The emergence of carbapenem resistance among gram-negative bacilli (GNB), mediated by carbapenemase production, has necessitated the development of a simple and accurate device for detecting minimum inhibitory concentrations (MICs) and resistance mechanisms, especially carbapenemase production. We evaluated the performance of the BD Phoenix NMIC-500 panel (BD Diagnostic Systems, Sparks, MD, USA) for antimicrobial susceptibility testing (AST) and carbapenemase-producing organism (CPO) detection. METHODS: We used 450 non-duplicate clinical GNB isolates from six general hospitals in Korea (409 Enterobacteriaceae and 41 glucose non-fermenting bacilli [GNFB] isolates). AST for meropenem, imipenem, ertapenem, ceftazidime, and ceftazidime/avibactam, and CPO detection were performed using the Phoenix NMIC-500 panel. Broth microdilution was used as the reference method for AST. The rates of categorical agreement (CA), essential agreement (EA), minor error (mE), major error (ME), and very major error (VME) were calculated in each antimicrobial. In addition, PCR and sequencing were performed to evaluate the accuracy of CPO detection by the BD Phoenix NMIC-500 panel, and the rate of correct identification was calculated. RESULTS: The CA rates were >90% for all antimicrobials tested with the Enterobacteriaceae isolates, except for imipenem (87.2%). The GNFB CA rates ranged from 92.7% to 100% for all antimicrobials. The ME rates were 1.7% for Enterobacteriaceae and 0% for GNFB. The panel identified 97.2% (243/250) of the carbapenemase-producing isolates. CONCLUSIONS: The BD Phoenix NMIC-500 panel shows promise for AST and CPO detection.


Subject(s)
Ceftazidime , Drug Resistance, Bacterial , Enterobacteriaceae , Glucose , Hospitals, General , Imipenem , Korea , Methods , Microbial Sensitivity Tests , Polymerase Chain Reaction
14.
Article in English | WPRIM | ID: wpr-739013

ABSTRACT

BACKGROUND: Escherichia coli and Klebsiella pneumoniae clinical isolates producing CTX-M extendedspectrum β-lactamases (ESBLs) were assessed for antimicrobial resistance phenotypes varied by group of enzymes. METHODS: A total of 1,338 blood isolates, including 959 E. coli and 379 K. pneumoniae, were studied. All the strains were collected between January and July 2017 from eight general hospitals in South Korea. The species were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined by disk diffusion methods and ESBL phenotypes by double-disk synergy tests using disks containing cefotaxime, ceftazidime, cefepime, aztreonam, and clavulanic acid (CA). The genes for β-lactamases were identified by PCR and sequencing. RESULTS: Of total microbes, 31.6% (303/959) E. coli and 24.0% (91/379) K. pneumoniae were resistant to cefotaxime and 28.1% (269/959) E. coli and 20.1% (76/379) K. pneumoniae were CTX-M-type ESBL producers. Among the detected CTX-M ESBLs, 58.0% (156/269) in E. coli and 86.8% (66/76) in K. pneumoniae belonged to group 1, 46.8% (126/269) in E. coli and 14.5% (11/76) in K. pneumoniae were group 9. Ten E. coli and one K. pneumoniae isolates co-produced both groups of CTX-M ESBL. The group 1 CTX-M producers had a higher level of resistance to cefotaxime, ceftazidime, cefepime, and aztreonam and exhibited stronger synergistic activities when combined with CA compared to group 9. CONCLUSION: ESBL phenotypes differ by CTX-M ESBL group and phenotype testing with drugs including 4th generation cephalosporins and monobactams is critical for screening CTX-M-producers with better sensitivity.


Subject(s)
Aztreonam , Cefotaxime , Ceftazidime , Cephalosporins , Clavulanic Acid , Diffusion , Escherichia coli , Hospitals, General , Klebsiella pneumoniae , Korea , Mass Screening , Mass Spectrometry , Monobactams , Phenotype , Pneumonia , Polymerase Chain Reaction
15.
Laboratory Medicine Online ; : 201-209, 2019.
Article in Korean | WPRIM | ID: wpr-760517

ABSTRACT

BACKGROUND: The aim of the present study was to determine the frequency of six efflux pump genes in Acinetobacter clinical isolates collected from South Korean hospitals. METHODS: In this study, we used a total of 339 Acinetobacter strains, comprising 279 Acinetobacter calcoaceticus–Acinetobacter baumannii (ACB) complex and 60 non-ACB complex strains. We performed specific PCR assays to detect adeG, adeB, adeE, adeY, abeM, and adeJ, transporter genes of the multidrug efflux pumps AdeFGH, AdeABC, AdeDE, AdeXYZ, AbeM, and AdeIJK, respectively. RESULTS: Frequencies of six efflux pump genes varied according to the species of Acinetobacter. Frequencies of adeE, abeM, and adeJ between A. baumannii group and A. nosocomialis group were found to be significantly different. Significant differences were found in the frequencies of adeB, adeE, adeY, and adeJ among the susceptible A. baumannii (SAB), multidrug-resistant A. baumannii (MDRAB), and extensively drug-resistant A. baumannii (XDRAB) groups within the 154 strains of A. baumannii. The frequencies of efflux pump genes in imipenem-susceptible and imipenem-nonsusceptible groups were significantly different for adeB, adeY, and adeJ. The frequencies of efflux pump genes in ciprofloxacin-susceptible and ciprofloxacin-nonsusceptible groups were significantly different for adeB and adeY. No significant difference was found in the frequency of efflux pump genes among groups sampled from different regions of Korea, across 86 strains of A. baumannii collected in 2012. CONCLUSIONS: The frequencies of six efflux pump genes obtained in this study demonstrate the fundamental epidemiological feature of efflux pump genes in Korean Acinetobacter clinical isolates.


Subject(s)
Acinetobacter , Gene Frequency , Genes, MDR , Korea , Polymerase Chain Reaction
16.
Article in English | WPRIM | ID: wpr-914594

ABSTRACT

BACKGROUND@#Smectite can serve as a drug delivery system and gentamicin-intercalated smectite hybrids are expected to supersede the standard therapy for Helicobacter pylori eradication. The aim of this study was to confirm whether the minimum inhibitory concentration (MIC) of aminoglycosides applied as smectite hybrids remained low against recently isolated H. pylori strains.@*MATERIALS AND METHODS@#A total of 140 strains were collected for a minimum period of 3 years. Antimicrobial susceptibility tests were performed, and the MICs of eight antibiotics (amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin, gentamicin, netilmicin, and tobramycin) were determined by using the Epsilometer test and following the European Committee on Antimicrobial Susceptibility Testing recommendations.@*RESULTS@#The resistance rate of clarithromycin was high, up to 30.7%, although it is a major antimicrobial agent used in standard therapy. The MIC50 and MIC90 of gentamicin (0.25 mg/L and 0.75 mg/L) and netilmicin (0.19 mg/L and 0.75 mg/L) were lower than other alternative therapies for H. pylori eradication. In clarithromycin-resistant strains, the MIC50 was 0.25 mg/L and the MIC90 was 1 mg/L for gentamicin; for netilmicin, the values were 0.25 mg/L and 0.75 mg/L, respectively.@*CONCLUSION@#Through the use of gentamicin and netilmicin, which have low MICs for H. pylori, aminoglycoside-intercalated smectite hybrids are expected to emerge as a new standard therapy for H. pylori eradication.

17.
Article in Korean | WPRIM | ID: wpr-816600

ABSTRACT

BACKGROUND: Antimicrobial resistance (AMR) is an issue not only with regard to public health, but also in terms of economic impact. AMR surveillance has mainly been carried out in general hospitals, and not in nursing hospitals. This study was conducted to investigate the AMR rate for bacterial strains isolated from nursing hospital samples.METHODS: Antimicrobial susceptibility testing (AST) results from a total of 23,518 bacterial isolates recovered from clinical specimens taken in 61 nursing hosals were analyzed. AST was conducted using Vitek 2 with AST cards specific for the bacterial strains.RESULTS: A total of 19,357 Gram-negative and 4,161 Gram-positive bacterial strains were isolated. Pseudomonas aeruginosa (n=6,384) and Escherichia coli (n=5,468) were the most prevalent bacterial species and, among Gram-positive bacteria, Staphylococcus aureus (n=1,565) was common. The AMR rate was high for the following strains: cefotaxime-resistant Klebsiella pneumoniae, 77.4%; cefotaxime-resistant E. coli, 70.6%; imipenem-resistant Acinetobacter baumannii, 90.3%; imipenem-resistant P. aeruginosa, 49.3%; oxacillin-resistant S. aureus, 81.1%, penicillin-resistant Enterococcus faecalis, 44.8%, and vancomycin-resistant Enterococcus faecium, 53.5%. AMR rate change varied by bacterial species and antimicrobial drug.CONCLUSION: AMR rates of major pathogens from nursing hospitals were higher than those from general hospitals with the exception of imipenem-resistant A. baumannii. Continuous monitoring and infection control strategies are needed.


Subject(s)
Acinetobacter baumannii , Enterococcus faecalis , Enterococcus faecium , Escherichia coli , Gram-Positive Bacteria , Hospitals, General , Infection Control , Klebsiella pneumoniae , Nursing , Pseudomonas aeruginosa , Public Health , Staphylococcus aureus
18.
Article in English | WPRIM | ID: wpr-713438

ABSTRACT

BACKGROUND: Listeriosis caused by Listeria monocytogenes has a high case-fatality rate (CFR) of approximately 20% to 30%. An increasing incidence of listeriosis has been reported in many countries recently. We investigated the annual incidence, clinical characteristics, and outcomes of listeriosis at three different hospitals in Korea and evaluated the effects of appropriate empiric antimicrobial treatments on patient outcomes. METHODS: We retrospectively collected the data of all culture-positive cases of human listeriosis from three hospitals of different sizes in Korea during 2006–2016 and calculated the annual number of cases and incidence per 100,000 admissions. RESULTS: A total of 58 patients with L. monocytogenes were included in this study. The incidence of listeriosis was significantly higher in 2013–2016 than in 2006–2012 (RR 3.1; 95% CI 1.79–5.36; P < 0.001), mainly because of an increase in patients over 60 years of age (RR 3.69; 95% CI 1.70–8.02; P < 0.001). Multivariate analysis showed that healthcare-associated infection (adjusted OR, 12.15; 95% CI, 2.56–86.01; P=0.004) and empirical treatment with first-line antimicrobial agents (adjusted OR, 0.08; 95% CI, 0.00–0.63; P=0.044) were associated with CFR. CONCLUSIONS: Healthcare-associated infections caused by L. monocytogenes are associated with high CFR. Adequate initial empirical treatments could reduce CFR, suggesting that careful consideration of an empirical antimicrobial regimen is warranted for elderly or immunocompromised patients admitted to the hospital.


Subject(s)
Aged , Anti-Infective Agents , Humans , Immunocompromised Host , Incidence , Korea , Listeria monocytogenes , Listeriosis , Multivariate Analysis , Retrospective Studies
19.
Article in English | WPRIM | ID: wpr-715662

ABSTRACT

BACKGROUND: We investigated the molecular epidemiological characteristics and antimicrobial susceptibility pattern of penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates to monitor the change in distribution of bla(TEM) in Korea. METHODS: We collected 804 PPNG isolates from diverse hospitals and clinics mainly located in Seoul, Korea, over a period of 11 years (2005–2015). Isolate susceptibility to seven antimicrobials was determined using the agar dilution test. The molecular epidemiological characteristics of the isolates were determined by Sanger sequencing of bla(TEM), N. gonorrhoeae multiantigen sequence typing (NG-MAST) and plasmid typing. RESULTS: Among 72 fully sequenced PPNG isolates, sixteen (22.2%) possessed TEM-135. All TEM-135 isolates had a common silent mutation (c.18C>T), which was previously unreported. We observed a pattern of continuous increase in the number of TEM-135 isolates since 2012. The median and 90% minimum inhibitory concentration of azithromycin were substantially lower in the TEM-135 group than in the non-PPNG and TEM-1 groups. All TEM-135 isolates showed different NG-MAST types and predominantly harbored Toronto/Rio (75%) plasmids. A comprehensive comparative analysis of PPNG with TEM-135 according to NG-MAST, plasmid type, and year of isolation revealed a wide distribution. CONCLUSIONS: The proportion of TEM-135 PPNG has continuously increased since 2012, in association with clonal spread. The difference at position 18 of the TEM-135 sequence can be interpreted as the existence of multiple clonal complexes. The possibility that TEM-135 was acquired via foreign plasmids requires careful follow-up and continuous monitoring of TEM-135 to ascertain whether it constitutes a step towards evolutionary change.


Subject(s)
Agar , Azithromycin , Drug Resistance, Microbial , Follow-Up Studies , Incidence , Korea , Microbial Sensitivity Tests , Neisseria gonorrhoeae , Neisseria , Plasmids , Seoul , Silent Mutation
20.
Article in English | WPRIM | ID: wpr-718328

ABSTRACT

BACKGROUND: The increasing morbidity and mortality rates associated with Acinetobacter baumannii are due to the emergence of drug resistance and the limited treatment options. We compared characteristics of colistin-resistant Acinetobacter baumannii (CR-AB) clinical isolates recovered from patients with and without prior colistin treatment. We assessed whether prior colistin treatment affects the resistance mechanism of CR-AB isolates, mortality rates, and clinical characteristics. Additionally, a proper method for identifying CR-AB was determined. METHODS: We collected 36 non-duplicate CR-AB clinical isolates resistant to colistin. Antimicrobial susceptibility testing, Sanger sequencing analysis, molecular typing, lipid A structure analysis, and in vitro synergy testing were performed. Eleven colistin-susceptible AB isolates were used as controls. RESULTS: Despite no differences in clinical characteristics between patients with and without prior colistin treatment, resistance-causing genetic mutations were more frequent in isolates from colistin-treated patients. Distinct mutations were overlooked via the Sanger sequencing method, perhaps because of a masking effect by the colistin-susceptible AB subpopulation of CR-AB isolates lacking genetic mutations. However, modified lipid A analysis revealed colistin resistance peaks, despite the population heterogeneity, and peak levels were significantly different between the groups. CONCLUSIONS: Although prior colistin use did not induce clinical or susceptibility differences, we demonstrated that identification of CR-AB by sequencing is insufficient. We propose that population heterogeneity has a masking effect, especially in colistin non-treated patients; therefore, accurate testing methods reflecting physiological alterations of the bacteria, such as phosphoethanolamine-modified lipid A identification by matrix-assisted laser desorption ionization-time of flight, should be employed.


Subject(s)
Acinetobacter baumannii , Acinetobacter , Bacteria , Colistin , Drug Resistance , Humans , In Vitro Techniques , Lipid A , Masks , Methods , Molecular Typing , Mortality , Population Characteristics
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