The Distribution of Carbapenem-Resistant Acinetobacter Species and High Prevalence of CC92 OXA-23-Producing in Community Hospitals in South Korea.

Background: Clinical isolates of species in South Korea are continuously exhibiting high rates of antimicrobial resistance to carbapenems, indicating that there are public health concerns among both healthcare-associated infections and community-associated infections. The aim of this study was to describe the prevalence and characteristics of carbapenem-resistant isolates originating from community hospitals.

Materials And Methods: A total of 817 non-duplicated species were isolated from December 2022 to July 2023 at long-term care facilities and general hospitals in 16 regions geographically distributed throughout South Korea.

Antibacterial effect of singlet oxygen depending on bacteria surface charge.

Here, we investigated the bactericidal effects of two types of photoinduced reactive oxygen species (ROS), superoxide anion and singlet oxygen, on bacteria with distinct surface charges. We fabricated photofunctional polymer films (PFPFs) capable of generating both types of ROS, and they were subjected to photodynamic inactivation tests for 12 various strains of Acinetobacter baumannii. The results showed that the type I ROS (superoxide anion) was significantly dependent on the surface charge of the bacteria owing to charge-charge repulsion, while the type II ROS (singlet oxygen) was independent of the surface charge of the bacteria.

Evaluation of Modified Sequential Multiplex PCR for Streptococcus pneumoniae Serotyping.

The aims of this study were to develop modified sequential multiplex PCR (SM-PCR) primer sets and to evaluate their ability and efficiency for serotype determination. We selected target serotypes for SM-PCR testing according to serotype prevalence as reported in Asian publications. The modified SM-PCR consisted of 6 groups of PCR reactions, and each reaction was performed using 5 primer pairs.

Emergence of IMP-4-Producing Enterobacter aerogenes Clinical Isolate.

Background: IMP-4 class B metallo-β-lactamase-producing Enterobacteriaceae are resistant to carbapenems. The aim of this study was to characterize of IMP-4 metallo-β-lactamase (MBL)-producing Enterobacter aerogenes clinical isolate.

Methods: IMP-4 MBL-producing E.

Molecular Characteristics of First IMP-4-Producing Sequence Type 74 and 194 in Korea.

The worldwide dissemination of carbapenemase-producing (CPE) has become a major therapeutic concern in clinical settings. is a major pathogen that causes serious hospital-acquired infections. We investigated the clinical characteristics and molecular mechanisms of the first IMP-4-producing clinical isolates in Korea.

Biology of : Pathogenesis, Antibiotic Resistance Mechanisms, and Prospective Treatment Options.

is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant , few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of is important.

Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Isolates Causing Invasive and Noninvasive Pneumococcal Diseases in Korea from 2008 to 2014.

Introduction. Streptococcus pneumoniae is an important pathogen with high morbidity and mortality rates. The aim of this study was to evaluate the distribution of common serotypes and antimicrobial susceptibility of S.

Identification of Acinetobacter Species Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

Background: Acinetobacter baumannii has a greater clinical impact and exhibits higher antimicrobial resistance rates than the non-baumannii Acinetobacter species. Therefore, the correct identification of Acinetobacter species is clinically important. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has recently become the method of choice for identifying bacterial species.

Detection of Carbapenemases in Clinical Enterobacteriaceae Isolates Using the VITEK AST-N202 Card.

Background: The rapid and accurate detection of carbapenemase-producing Enterobacteriaceae (CPE) in clinical microbiology laboratories is essential for the treatment and control of infections caused by these microorganisms. This study was performed to evaluate the ability of the VITEK AST-N202 card to detect CPE isolates.

Materials And Methods: A total of 43 (Klebsiella pneumoniae, n = 37; Escherichia coli, n = 3; and Enterobacter cloacae, n = 3) CPE isolates and 79 carbapenemase-non-producing Enterobacteriaceae (CNE) isolates were included in this study.

Epidemiology and Characteristics of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa.

Metallo-β-lactamase-producing Pseudomonas aeruginosa (MPPA) is an important nosocomial pathogen that shows resistance to all β-lactam antibiotics except monobactams. There are various types of metallo-β-lactamases (MBLs) in carbapenem-resistant P. aeruginosa including Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), Sao Paulo metallo-β-lactamase (SPM), Germany imipenemase (GIM), New Delhi metallo-β-lactamase (NDM), Florence imipenemase (FIM).

In Vivo Selection of Pan-Drug Resistant Acinetobacter baumannii during Antibiotic Treatment.

Purpose: Colistin resistance in Acinetobacter baumannii (A. baumannii) is mediated by a complete loss of lipopolysaccharide production via mutations in lpxA, lpxC, and lpxD gene or lipid A modifications via mutations in the pmrA and pmrB genes. However, the exact mechanism of therapy-induced colistin resistance in A.

Characteristics of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa in Korea.

Background: The aim of this study was to investigate the molecular epidemiological characteristics of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa clinical isolates in Korea.

Materials And Methods: Three hundred and twenty nine P. aeruginosa clinical isolates were collected from 23 general hospitals in Korea from March to June 2014.

Evaluation of peptide nucleic acid-mediated multiplex real-time PCR kits for rapid detection of carbapenemase genes in gram-negative clinical isolates.

The emergence of clinical isolates of carbapenemase-producing microbes confers multidrug-resistance to these bacteria and renders them difficult to treat. This study was performed to evaluate peptide nucleic acid (PNA) probe-based multiplex real-time PCR kits used to detect carbapenemase genes. In total, 324 carbapenemase genes, collected from 318 gram-negative clinical isolates in 36 different hospital laboratories, were assayed to evaluate multiplex real-time PCR kits (PANAGENE; Daejeon, Korea).

Combined use of the modified Hodge test and carbapenemase inhibition test for detection of carbapenemase-producing Enterobacteriaceae and metallo-β-lactamase-producing Pseudomonas spp.

Background: We evaluated the combined use of the modified Hodge test (MHT) and carbapenemase inhibition test (CIT) using phenylboronic acid (PBA) and EDTA to detect carbapenemase-producing Enterobacteriaceae (CPE) and metallo-β-lactamase (MBL)-producing Pseudomonas spp.

Methods: A total of 49 isolates of CPE (15 Klebsiella pneumoniae carbapenemase [KPC], 5 Guiana extended-spectrum β-lactamase [GES]-5, 9 New Delhi metallo-β-lactamase [NDM]-1, 5 Verona integron-encoded metallo-β-lactamase [VIM]-2, 3 imipenem-hydrolyzing β-lactamase [IMP], and 12 oxacillinase [OXA]-48-like), 25 isolates of MBL-producing Pseudomonas spp. (14 VIM-2 and 11 IMP), and 35 carbapenemase-negative controls were included.

Clonal and horizontal spread of the blaOXA-232 gene among Enterobacteriaceae in a Korean hospital.

All 16 Klebsiella pneumoniae isolates and both Escherichia coli isolates harbored the bla(OXA-232) and bla(CTX-M-15) genes. Furthermore, all 16 K. pneumoniae isolates belonged to a unique pulsed-field gel electrophoresis clone and were assigned to an identical sequence type (ST14).

Comparison of pulsed-field gel electrophoresis & repetitive sequence-based PCR methods for molecular epidemiological studies of Escherichia coli clinical isolates.

Background & Objectives: PFGE, rep-PCR, and MLST are widely used to identify related bacterial isolates and determine epidemiologic associations during outbreaks. This study was performed to compare the ability of repetitive sequence-based PCR (rep-PCR) and pulsed-field gel electrophoresis (PFGE) to determine the genetic relationships among Escherichia coli isolates assigned to various sequence types (STs) by two multilocus sequence typing (MLST) schemes.

Methods: A total of 41 extended-spectrum β-lactamase- (ESBL-) and/or AmpC β-lactamase-producing E.

The drug susceptibility profile and inducible resistance to macrolides of Mycobacterium abscessus and Mycobacterium massiliense in Korea.

We conducted drug susceptibility testing (DST) against various antimicrobial agents, including new candidate drugs, and investigated the relationship between inducible resistance (IR) to macrolides and erm(41) gene in Mycobacterium abscessus complex. Sixty-two isolates of M. abscessus complex from 2 tertiary care hospitals in South Korea were tested against 10 antimicrobial agents.

Risk factors for mortality in patients with bloodstream infections caused by carbapenem-resistant Pseudomonas aeruginosa: clinical impact of bacterial virulence and strains on outcome.

The incidence of carbapenem-resistant Pseudomonas aeruginosa (CRPA) bacteremia has increased in recent years, and infections caused by CRPA result in higher mortality than those caused by susceptible strains. This study was performed to evaluate the risk factors for mortality and to study the impact of virulence factors and bacterial strains on clinical outcomes in patients with CRPA bacteremia. Data on 63 episodes of CRPA bacteremia that have occurred between January 1, 2007, and December 31, 2009, in a teaching hospital (2000 beds) in Seoul, Korea, were analyzed.

Misidentification of Candida guilliermondii as C. famata among strains isolated from blood cultures by the VITEK 2 system.

Introduction. The aim of this study was to differentiate between Candida famata and Candida guilliermondii correctly by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and gene sequencing. Methods.

In vivo emergence of colistin resistance in Acinetobacter baumannii clinical isolates of sequence type 357 during colistin treatment.

This study was performed to investigate the mechanisms of in vivo acquisition of colistin resistance in A. baumannii during colistin treatment. Three colistin-susceptible/resistant pairs of A.

Molecular epidemiology of Pseudomonas aeruginosa clinical isolates from Korea producing β-lactamases with extended-spectrum activity.

This study was performed to investigate the prevalence and molecular epidemiology of Pseudomonas aeruginosa isolates from Korea that produce enzymes with extended-spectrum (ES) activity to β-lactams. A total of 205 non-duplicate P. aeruginosa clinical isolates were collected from 18 university hospitals in Korea.

Broth microdilution methods using B-lactamase inhibitors for the identification of Klebsiella pneumoniae carbapenemases and metallo-β-lactamases in Gram-negative bacilli.

This study was designed to evaluate the performance of the broth microdilution (BMD) test in detecting the production of Klebsiella pneumoniae carbapenemases (KPCs) and metallo-β-lactamases (MBLs) in clinical isolates of gram-negative bacilli by using various β-lactamase inhibitors. A carbapenemase detection test, comprised of Mueller-Hinton broth containing serial twofold dilutions of imipenem or meropenem with and without aminophenylboronic acid (APB), phenylboronic acid (PB), cloxacillin (CLX), dipicolinic acid (DPA), or EDTA, was evaluated against 31 Klebsiella pneumoniae strains with KPC, 21 MBL-producers (3 Enterobacteriaceae and 18 non-fermenters), and 26 carbapenemase-non-producing Enterobacteriaceae strains. A threefold or greater decrease in the MIC of imipenem or meropenem with β-lactamase inhibitors, when compared with the imipenem or meropenem alone, was considered a positive result.

Risk factors and molecular epidemiology of community-onset extended-spectrum β-lactamase-producing Escherichia coli bacteremia.

Purpose: Inadequate empirical therapy for severe infections caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBLEC) is associated with poor outcomes. This study was designed to investigate risk factors for community-onset ESBLEC bacteremia at admission to a tertiary care hospital.

Materials And Methods: A case-control study was performed that included all episodes of ESBLEC bacteremia in the outpatient department or within 48 hours of admission from January 2005 to March 2009.

Standardization of multilocus sequence typing scheme for Mycobacterium abscessus and Mycobacterium massiliense.

This study aims to develop a multilocus sequence typing (MLST) scheme for Mycobacterium abscessus complex for the typing of stains within each species. A total of 89 clinical isolates of M. abscessus complex from 71 patients of 2 tertiary care hospitals in South Korea were included.