Analyzing Korean Public Health Centers' Infectious Disease Disaster Response Experiences with a Focus on Business Continuity.

Objective: This study aims to provide basic data for establishing strategies to maintain the core functions of health centers, and enable an effective response to emergency tasks in the event of future infectious disease disasters. Methods: The participants were 41 workers from two public health centers in Seoul. They all had prior experience in responding to the early and middle stages of the COVID-19 pandemic. Data were collected through Focus Group Discussions, and then analyzed using the deductive method of content analysis. Results: The participants' experiences during the infectious disease disaster crisis were examined through ten categories: governance and coordination, information management, human resources, essential medical supplies and equipment, infrastructure, administration, finance and logistics, community engagement and risk communication, delivery of essential services, security, and additional considerations for vulnerable populations. The analysis of the results made it apparent that new systems and policies were imperative for responding appropriately to the concerns and experiences of the public healthcare center staff, and for improving the response to future epidemics. Conclusion: We found that to prepare for infectious disaster situations in the future, it is necessary for health centers to establish a mid- to long-term business continuity plan to ensure the continuation and stability of their operations. Additionally, it was found that health professionals in public health centers also believe in the necessity of education and training programs on disaster preparedness, based on Business Continuity Planning proposed by the World Health Organization. They deem these essential to sustain routine tasks for the management of the health of local community residents during outbreaks of novel infectious diseases in the future.

Prevalence and Molecular Characterization of Vancomycin Variable Enterococcus faecium Isolated From Clinical Specimens.

Vancomycin variable Enterococcus (VVE) bacteria are phenotypically susceptible to vancomycin, but they harbor the vanA gene. We aimed to ascertain the prevalence of VVE among clinically isolated vancomycin-susceptible Enterococcus faecium (VSE) isolates, as well as elucidate the molecular characteristics of the vanA gene cluster within these isolates. Notably, we investigated the prevalence and structure of the vanA gene cluster of VVE. Between June 2021 and May 2022, we collected consecutive, non-duplicated vancomycin-susceptible Enterococcus faecium (VSE) samples. Real-time PCR was performed to detect the presence of vanA, vanB, and vanC. Overlapping PCR with sequencing and whole-genome sequencing were performed for structural analysis. Sequence types (STs) were determined by multilocus sequence typing. Exposure testing was performed to assess the ability of the isolates to acquire vancomycin resistance. Among 282 VSE isolates tested, 20 isolates (7.1%) were VVE. Among them, 17 isolates had partial deletions in the IS1216 or IS1542 sequences in vanS (N=10), vanR (N=5), or vanH (N=2). All VVE isolates belonged to the CC17 complex and comprised five STs, namely ST17 (40.0%), ST1421 (25.0%), ST80 (25.0%), ST787 (5.0%), and ST981 (5.0%). Most isolates were related to three hospital-associated clones (ST17, ST1421, and ST80). After vancomycin exposure, 18 of the 20 VVEs acquired vancomycin resistance. Considering the high reversion rate, detecting VVE by screening VSE for vanA is critical for appropriate treatment and infection control.

[Topic Modeling and Keyword Network Analysis of News Articles Related to Nurses before and after "the Thanks to You Challenge" during the COVID-19 Pandemic].

PURPOSE: This study was conducted to assess public awareness and policy challenges faced by practicing nurses. METHODS: After collecting nurse-related news articles published before and after 'the Thanks to You Challenge' campaign (between December 31, 2019, and July 15, 2020), keywords were extracted via preprocessing. A three-step method keyword analysis, latent Dirichlet allocation topic modeling, and keyword network analysis was used to examine the text and the structure of the selected news articles. RESULTS: Top 30 keywords with similar occurrences were collected before and after the campaign. The five dominant topics before the campaign were: pandemic, infection of medical staff, local transmission, medical resources, and return of overseas Koreans. After the campaign, the topics 'infection of medical staff' and 'return of overseas Koreans' disappeared, but 'the Thanks to You Challenge' emerged as a dominant topic. A keyword network analysis revealed that the word of nurse was linked with keywords like thanks and campaign, through the word of sacrifice. These words formed interrelated domains of 'the Thanks to You Challenge' topic. CONCLUSION: The findings of this study can provide useful information for understanding various issues and social perspectives on COVID-19 nursing. The major themes of news reports lagged behind the real problems faced by nurses in COVID-19 crisis. While the press tends to focus on heroism and whole society, issues and policies mutually beneficial to public and nursing need to be further explored and enhanced by nurses.

Predominance and clonal spread of CTX-M-15 in cefotaxime-resistant Klebsiella pneumoniae in Korea and their association with plasmid-mediated quinolone resistance determinants.

INTRODUCTION: ß-lactams and fluoroquinolones are extensively used worldwide in the treatment of infections caused by Enterobacterales. In this study, we investigated the prevalence of extended-spectrum ß-lactamases (ESBL), their correlation with plasmid-mediated quinolone resistance determinants (PMQR) and clonal distribution among the cefotaxime-resistant K. pneumoniae isolates. METHODS: In Korea, a total of 429 K. pneumoniae collected in 2015 were studied. Antimicrobial susceptibility test for cefotaxime, ciprofloxacin and levofloxacin was performed by broth microdilution method. By PCR and/or sequencing, mutations in gyrA and parC genes, PMQR genes and ESBL were identified. Multilocus-sequence-type (MLST) was determined for isolates harboring CTX-M-15. RESULTS: Among the 149 K. pneumoniae showing cefotaxime MICs of >1 µg/ml, 142 (95.3%) isolates were ESBL-producers and CTX-M-15 was predominant (99 isolates). Among the 142 ESBL-producers, mutations in gyrA and parC were found in 112 (78.9%) and 93 isolates (65.5%), respectively. PMQR genes were detected in 141 isolates and the non-susceptibility rate to ciprofloxacin and levofloxacin was 95.1% (135/142) and 82.4% (117/142), respectively. The most frequently found PMQR combination was qnrB-aac(6')-Ib-cr-oqxAB, (58/142, 40.8%). By MLST, four major STs/CC: ST48, ST392, ST307 and CC15 accounted for 67% of the CTX-M-15 producers and the prevalence of qnrB was significantly higher in these four major STs/CC than other groups (P = 0.004). Of note, we found the additive effect of PMQR genes; the more PMQR genes, the higher ciprofloxacin MICs. CONCLUSIONS: CTX-M-15 was predominant among the cefotaxime-resistant K. pneumoniae and co-harboring CTX-M-15 and PMQR genes, especially qnrB, seems to contribute the spread of high risk clones.

Evaluation of the BioFire Gastrointestinal Panel to Detect Diarrheal Pathogens in Pediatric Patients.

Infectious diarrhea is a global pediatric health concern; therefore, rapid and accurate detection of enteropathogens is vital. We evaluated the BioFire® FilmArray® Gastrointestinal (GI) Panel with that of comparator laboratory tests. Stool samples of pediatric patients with diarrhea were prospectively collected and tested. As a comparator method for bacteria, culture, conventional PCR for diarrheagenic E. coli, and Allplex GI-Bacteria(I) Assay were tested. For discrepancy analysis, BD MAX Enteric Bacterial Panel was used. As a comparator method for virus, BD MAX Enteric Virus Panel and immunochromatography was used and Allplex GI-Virus Assay was used for discrepancy analysis. The "true positive" was defined as culture-positive and/or positive results from more than two molecular tests. Of the 184 stool samples tested, 93 (50.5%) were true positive for 128 pathogens, and 31 (16.9%) were positive for multiple pathogens. The BioFire GI Panel detected 123 pathogens in 90 of samples. The BioFire GI Panel demonstrated a sensitivity of 100% for 12 targets and a specificity of >95% for 16 targets. The overall positive rate and multiple pathogen rate among patients in the group without underlying diseases were significantly higher than those in the group with hematologic disease (57.0% vs. 28.6% (p = 0.001) and 20.4% vs. 4.8% (p = 0.02), respectively). The BioFire GI Panel provides comprehensive results within 2 h and may be useful for the rapid identification of enteropathogens.

Performance evaluation of automated BD Phoenix NMIC-500 panel for carbapenemase detection in carbapenem-resistant and carbapenem-susceptible Enterobacterales.

Rapid detection of carbapenemases and accurate reporting of carbapenem MICs is critical for appropriate treatment and infection control. We evaluated the BD Phoenix NMIC-500 panel for detection and classification of carbapenemases and antimicrobial susceptibility testing (AST) for carbapenems. A total of 235 isolates were tested; 47 carbapenemase-producing Enterobacterales, 52 non-carbapenemase-producing carbapenem-resistant Enterobacterales (non-CP-CRE), 136 carbapenem-susceptible Enterobacterales (CSE). The sensitivity of carbapenemase-producing organism (CPO) detection was 97.9%, the specificity was 100% for CSE but 32.7% for non-CP-CREs. All the 35 false-positive cases were non-CP-CREs; 23 out of the 35 were determined as untyped carbapenemase producer (CP), nine were mistyped as class B, and three were as class A. The detection rate/correct classification rate for class A, B, and D carbapenemase was 100%/78.6%, 100%/100%, and 80%/60%, respectively. To supplement the low specificity, it is suggested to report carbapenemase-producer (CP) positive results as "strongly suspicious for carbapenem resistance but carbapenemase production needs to be confirmed" and perform the confirmatory test. The EA and CA for ertapenem, imipenem, and meropenem was 99.1%/99.6%, 89.4%/90.6%, and 95.3%/95.7%. In conclusion, the BD Phoenix CPO detect panel provides advantage in that the carbapenemase test is automated and the results can be obtained within 6 h but the low specificity in CREs needs to be improved. In addition, accurate reporting of meropenem MICs will be helpful for clinicians to choose treatment options.

Microbial assessment of medicinal herbs (Cnidii Rhizoma and Alismatis Rhizoma), effects of electron beam irradiation and detection characteristics.

Medicinal herbs comprise of heavy microbial contaminations. This study aimed to assess microbial hazards including foodborne pathogens in 20 commercial medicinal herbs, Cnidii Rhizoma (C1-C10) and Alismatis Rhizoma (T1-T10) as well as to evaluate irradiation effects of E-beam on microbial load and detection chracteristics. Four samples (C5, C10, T1, T8) from both herbs with higher microbial load were selected for evaluating the irradiation effect of E-beam (up to 10 kGy) on microbial load and radiation-induced changes in detection markers by standard methods (Codex, Korean Food Code), such as direct epifluorescent filter technique/aerobic plate count (DEFT/APC), photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR). DEFT/APC revealed non-evidence of pre-sterilization of all samples. PSL differentiated irradiated samples (1, 5, and 10 kGy) of both herbs from non-irradiated (control: 0 kGy). Both TL and ESR methods validated PSL screening results by detecting radiation-induced markers from E-beam irradiated medicinal herbs.

Development of carbapenem-based fluorogenic probes for the clinical screening of carbapenemase-producing bacteria.

This report describes the synthesis of a library of fluorogenic carbapenemase substrates consisting of carbapenem derivatives, fluorescence dyes, and active cleavable linkers and their evaluation for specifically detecting carbapenemase-producing organisms (CPOs). We synthesized a series of compounds having three different types of linkers such as benzyl ether, carbamate, and amine using hydroxymethyl carbapenem 7a and hydroxyallyl carbapenem 7b as key intermediates. Probe 1b exhibited high stability and a prompt turn-on fluorescence signal upon hydrolysis by carbapenemases. In particular, the screening of clinical samples indicated that the probe 1b exhibited excellent selectivity to the CPOs over other ß-lactamases or non-carbapenemase producing bacteria, which may be of clinical use for the rapid and accurate detection of CPOs for timely diagnosis and treatment.

Performance of a Novel Fluorogenic Assay for Detection of Carbapenemase-Producing Enterobacteriaceae from Bacterial Colonies and Directly from Positive Blood Cultures.

Rapid and accurate detection of carbapenemase-producing Enterobacteriaceae (CPE) is critical for appropriate treatment and infection control. We compared a rapid fluorogenic assay using a carbapenem-based fluorogenic probe with other phenotypic assays: modified carbapenem inactivation method (mCIM), Carba NP test (CNP), and carbapenemase inhibition test (CIT). A total of 217 characterized isolates of Enterobacteriaceae were included as follows: 63 CPE; 48 non-carbapenemase-producing carbapenem-resistant Enterobacteriaceae (non-CP-CRE); 53 extended-spectrum ß-lactamase producers; and 53 third-generation-cephalosporin-susceptible isolates. The fluorogenic assay using bacterial colonies (Fluore-C) was conducted by lysing the isolates followed by centrifugation and mixing the supernatant with fluorogenic probe. In addition, for the fluorogenic assay using spiked blood culture bottles (Fluore-Direct), pellets were obtained via the saponin preparation method, which can directly identify the pathogens using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The fluorescence signal was measured over 50 min using a fluorometer. The fluorescent signal of CPE was significantly higher than that of non-CPE in both Fluore-C (median relative fluorescence units [RFU] [range], 5,814 [240 to 32,009] versus 804 [36 to 2,480], respectively; P < 0.0001) and Fluore-Direct (median RFU [range], 10,355 [1,689 to 31,463] versus 1,068 [428 to 2,155], respectively; P < 0.0001) tests. Overall, positive and negative percent agreements of Fluore-C, mCIM, CNP, CIT, and Fluore-Direct were 100% and 98.7%, 98.3% and 97.5%, 88.1% and 100%, 96.4% and 98.7%, and 98.3% and 98.1%, respectively. The relatively lower positive percent agreement (PPA) of CNP was mainly observed in OXA-type CPE. The fluorogenic assay showed excellent performance with bacterial colonies and also directly from positive blood cultures. We included many non-CP-CRE isolates for strict evaluation. The fluorogenic assay will be a useful tool for clinical microbiology laboratories.

Effect of E-Beam Irradiation on Microbial Load, Stability of Active Components, and Anti-Inflammatory Activity of Cnidii Rhizoma and Alismatis Rhizoma.

To reduce microbial loads in medicinal herbs, Cnidii Rhizoma and Alismatis Rhizoma were subjected to electron-beam (e-beam) irradiation at doses (≤10 kGy) as permitted by the Korean Food Code. The effects of e-beam irradiation on the microbial load, stability of the active components, and anti-inflammatory activity of medicinal herbs were determined. We observed that the total aerobic bacteria (TAB; 4.0-7.0 log CFU/g), yeasts and molds (Y&M; 3.3-6.8 log CFU/g), and coliform counts (CC; 3.2-3.8 log CFU/g) in both herb samples were effectively reduced in a dose-dependent manner, resulting in acceptable levels of <3.0 log CFU/g in TAB and Y&M and negative in CC at 10 kGy irradiation. The concentration of the active components (0.87-4.22 mg/g) of Cnidii Rhizoma, including z-ligustilide, chlorogenic acid, senkyunolide A, and ferulic acid, in order of prevalence and those (0.86-2.76 mg/g) of Alismatis Rhizoma, including Alisol B acetate and Alisol B, were not changed at irradiation doses of ≤10 kGy. The extracts of e-beam irradiated Cnidii Rhizoma and Alismatis Rhizoma showed a reduced production of inflammation-related factors, such as nitric oxide, prostaglandin E2, interleukin (IL)-1ß, and IL-6, in a concentration-dependent manner, which was induced by lipopolysaccharide in RAW 264.7 cell. However, there was no significant difference observed at e-beam irradiation doses of 0, 1, 5, and 10 kGy. Thus, we confirm that e-beam irradiation up to 10 kGy was effective for the control of microbial load in Cnidii Rhizoma and Alismatis Rhizoma without causing considerable changes in their major active components and anti-inflammatory activity. The results show the potential of e-beam application for sanitization of medicinal herbs.

Clinical characteristics and rhythm outcome of catheter ablation of hemodynamically corrected valvular atrial fibrillation.

BACKGROUND: Although the hemodynamic burden and structural substrate contribute to valvular atrial fibrillation (VAF) mechanisms, the role of catheter ablation has rarely been reported. We investigated the clinical characteristics, mapping findings, and long-term rhythm outcomes after catheter ablation of hemodynamically corrected VAF. METHODS: We compared 77 patients with VAF (46.8% male, 52.7±8.8 years old, 46.8% paroxysmal AF, 24.7% with maze procedures) and 2244 patients with non-VAF (NVAF) who underwent catheter ablation. Among the VAF patients, 44 (57.1%) had mechanical valve AF (MV-AF) and 33 (42.9%) underwent a prior mitral valvuloplasty (MVP-AF). We analyzed the catheter ablation rhythm outcomes for MV-AF and MVP-AF. RESULTS: The left atrial (LA) diameter was greater (p<0.001), LA voltage lower (p<0.001), and procedure-related complication rate higher (mainly sinus node dysfunction, p=0.004) for VAF than NVAF. During 70.2±1.8 months of follow-up, the rhythm outcome of VAF did not significantly differ from that of NVAF after catheter ablation (log rank p=0.399), even after excluding patients with maze procedures (log rank p=0.629). The clinical recurrence rates did not differ between the MV-AF and MVP-AF groups (log rank p=0.244), or between patients with prior maze procedures and those without (log rank p=0.651). The main conduction recovery sites of previous maze procedures were the perimitral (84.2%) and cavotricuspid isthmus (84.2%) areas, and recurrence mechanisms were macroreentry (63.2%) and focal/microreentry (26.3%) at scar border zones. CONCLUSIONS: Although hemodynamically corrected VAF was associated with advanced LA remodeling, the rhythm outcome did not significantly differ from that of NVAF after catheter ablation.

Klebsiella pneumoniae Carbapenemase Producers in South Korea between 2013 and 2015.

Between 2014 and 2015, the Klebsiella pneumoniae carbapenemase (KPC) was becoming endemic in South Korea. To assess this period of transition, we analyzed KPC producers in terms of molecular epidemiology. A total of 362 KPC-producing Enterobacteriaceae strains, including one from 2013, 13 from 2014, and 348 from 2015, were actively collected from 60 hospitals throughout the peninsula. Subtypes of KPC were determined by PCR and direct sequencing, and isotypes of Tn4401 (the transposon flanking the blaKPC gene) were specified by PCR using isotype-specific primers and direct sequencing. Sporadic occurrence of KPC-producing Enterobacteriaceae was initially observed around Seoul, which is the most crowded district of the country, and these strains rapidly disseminated in 2014, to the other parts of the country in 2015. The bacterial clones responsible for the extreme epidemiological transition were K. pneumoniae ST307 (46.2%) and ST11 (21.3%). Less frequently, E. coli (4.7%), Enterobacter spp. (1.4%), and other Enterobacteriaceae members (1.7%) producing the enzyme were identified. The blaKPC-2 gene bracketed by Tn4401a (72.1%) was the most prevalent mobile genetic element responsible for the dissemination, and the same gene carried either by Tn4401b (2.2%) or Tn4401c (6.6%) was identified at a lesser frequency. The genes blaKPC-3 (1.6%) and blaKPC-4 (6.4%), both flanked by Tn4401b, were occasionally identified. This study showed endemic dissemination of KPC producers in 2015 due to a clonal spread of two K. pneumoniae strains. Further systemic surveillance is needed to monitor dissemination of KPC-producers.

Carbapenemase-producing Enterobacteriaceae in South Korea: a report from the National Laboratory Surveillance System.

AIM: To assess the epidemiology of carbapenemase-producing Enterobacteriaceae (CPE) in South Korea. MATERIALS & METHODS: From 2011 to 2015, 2487 carbapenem-nonsusceptible Enterobacteriaceae were collected through the Korean National Laboratory Surveillance System. Disk-diffusion for antimicrobial susceptibility, PCR/sequencing to detect carbapenemase genes and multilocus sequence typing for molecular epidemiology were carried out. RESULTS: The number of carbapenem-nonsusceptible Enterobacteriaceae was increasing approximately 1.5-fold per year and the proportion of CPEs was exponentially confirmed from 2014. KPC was the most dominant, mostly associated with Klebsiella pneumoniae ST11 and ST307, NDM was the second and OXA-48-like was the third dominant carbapenemases. The IMP, VIM and GES-5 CPEs were identified sporadically. CONCLUSION: The nation-wide spreads of KPC, NDM and OXA-48-like CPEs were in an alarming epidemiological stage.

Extensively Drug-Resistant Escherichia coli Sequence Type 1642 Carrying an IncX3 Plasmid Containing the blaKPC-2 Gene Associated with Transposon Tn4401a.

BACKGROUND: Extensively drug-resistant (XDR) Enterobacteriaceae carrying the bla(KPC) gene have emerged as a major global therapeutic concern. The purpose of this study was to analyze the complete sequences of plasmids from KPC-2 carbapenemase-producing XDR Escherichia coli sequence type (ST) 1642 isolates. METHODS: We performed antimicrobial susceptibility testing, PCR, multilocus sequence typing (MLST), and whole-genome sequencing to characterize the plasmid-mediated KPC-2-producing E. coli clinical isolates. RESULTS: The isolates were resistant to most available antibiotics, including meropenem, ampicillin, ceftriaxone, gentamicin, and ciprofloxacin, but susceptible to tigecycline and colistin. The isolates were identified as the rare ST1642 by MLST. The isolates carried four plasmids: the first 69-kb conjugative IncX3 plasmid harbors bla(KPC-2) within a truncated Tn4401a transposon and bla(SHV-11) with duplicated conjugative elements. The second 142-kb plasmid with a multireplicon consisting of IncQ, IncFIA, and IncIB carries bla(TEM-1b) and two class 1 integrons. This plasmid also harbors a wide variety of additional antimicrobial resistance genes including aadA5, dfrA17, mph(A), sul1, tet(B), aac(3')-IId, strA, strB, and sul2. CONCLUSIONS: The complete sequence analysis of plasmids from an XDR E. coli strain related to persistent infection showed the coexistence of a bla(KPC-2)-carrying IncX3-type plasmid and a class 1 integron-harboring multireplicon, suggesting its potential to cause outbreaks. Of additional clinical significance, the rare ST1642, identified in a cat, could constitute the source of human infection.

A stepwise approach to conduit puncture for electrophysiological procedures in patients with Fontan circulation.

Aims: In patients with Fontan circulation, the conduit may be punctured for electrophysiological procedures. We evaluated the feasibility and safety of a stepwise approach to conduit puncture in adults who have undergone Fontan operation. Methods and results: We included 13 consecutive patients with lateral tunnel or extracardiac conduit Fontan circulation [median age (interquartile range), 24.0 (16.0-25.0) years; seven men] who had undergone electrophysiological procedures. We performed a stepwise approach to conduit puncture: 1st, Brockenbrough needle; 2nd, Brockenbrough needle with snare; 3rd, extra-steep Brockenbrough needle with/without snare; 4th radiofrequency transseptal needle with/without snare; 5th, wiring through the puncture; 6th, conduit dilation with angioplasty balloon; 7th, non-compliant or cutting balloon; and 8th, Inoue dilator. In 12 patients, conduit puncture was successful. In two, one, and two patients with a lateral tunnel made of the pericardium or right atrial wall, conduit puncture was performed by steps 1st, 2nd, and 4th, respectively. In one, three, two, and one patient with the Goretex lateral tunnel or extracardiac conduit, conduit puncture was performed by steps 1st, 6th, 7th, and 8th, respectively. Puncture time was significantly longer in patients with Goretex conduits than with pericardial conduits [62.0 (50.0-120.0) and 11.5 (10.0-14.8) min, respectively; P < 0.001]. A snare was necessary in patients with angles ≤ 35° between the conduit wall and vertical line. Conclusion: A stepwise conduit puncture approach is feasible and safe in patients with lateral tunnel and extracardiac conduit Fontan circulation. Goretex conduit puncture was more difficult than pericardial conduit puncture.

The blaOXA-23-associated transposons in the genome of Acinetobacter spp. represent an epidemiological situation of the species encountering carbapenems.

Objectives: High rates of carbapenem resistance in the human pathogen Acinetobacter baumannii threaten public health and need to be scrutinized. Methods: A total of 356 A. baumannii and 50 non-baumannii Acinetobacter spp. (NBA) strains collected in 2013 throughout South Korea were studied. The type of blaOXA-23 transposon was determined by PCR mapping and molecular epidemiology was assessed by MLST. Twelve representative strains and two comparative A. baumannii were entirely sequenced by single-molecule real-time sequencing. Results: The carbapenem resistance rate was 88% in A. baumannii, mainly due to blaOXA-23, with five exceptional cases associated with ISAba1-blaOXA-51-like. The blaOXA-23 gene in A. baumannii was carried either by Tn2006 (44%) or Tn2009 (54%), with a few exceptions carried by Tn2008 (1.6%). Of the NBA strains, 14% were resistant to carbapenems, two with blaOXA-58 and five with blaOXA-23 associated with Tn2006. The Tn2006-possessing strains belonged to various STs, whereas Tn2008- and Tn2009-possessing strains were limited to ST208 and ST191, respectively. The three transposons were often multiplied in the chromosome, and the gene copy number and the carbapenem MICs presented linear relationships either very strongly for Tn2008 or moderately for Tn2006 and Tn2009. Conclusions: The dissemination of Tn2006 was facilitated by its capability for intercellular transfer and that of Tn2009 was attributable to successful dissemination of the ST191 bacterial host carrying the transposon. Tn2008 was infrequent because of its insufficient ability to undergo intercellular transfer and the scarce bacterial host A. baumannii ST208. Gene amplification is an adaptive mechanism for bacteria that encounter antimicrobial drugs.

Massilia varians Isolated from a Clinical Specimen.

We report a case of Massilia varians isolated from a deep finger wound following orthopedic surgery on an immunocompetent patient. The bacterium was identified by 16S rDNA sequence analysis. This is the first case of M. varians isolated from a clinical specimen since the first report in 2008.

Outbreak of KPC-2-producing Enterobacteriaceae caused by clonal dissemination of Klebsiella pneumoniae ST307 carrying an IncX3-type plasmid harboring a truncated Tn4401a.

Over a 5-month period between the end of June and the beginning of November in 2015, a KPC-producing Enterobacteriaceae outbreak occurred in a general hospital in Busan, South Korea, being associated with a total of 50 clinical isolates from 47 patients. Multilocus sequence typing and pulsed-field gel electrophoresis were carried out for strain typing and whole-genome sequencing was performed to characterize the plasmids. A clonal spread of K. pneumoniae sequence type 307 (ST307) carrying a self-transferable IncX3-type plasmid harboring blaKPC-2 was responsible for the outbreak. Sporadic emergence of K. pneumoniae ST697 carrying an IncFII-type plasmid and a ST11 isolate harboring a small plasmid devoid of any known origin of replication were observed to be associated with blaKPC-3, but no further dissemination of these strains was identified. The results indicated a healthcare-associated infection associated with a blaKPC-harboring plasmid dissemination and a clonal spread of KPC-producing Enterobacteriaceae.

In vitro antimicrobial synergy of colistin with rifampicin and carbapenems against colistin-resistant Acinetobacter baumannii clinical isolates.

Increased use of colistin in a clinical setting had resulted in the emergence of colistin-resistant (CoR) Acinetobacter baumannii. Combination therapy has been studied as a new approach to treat infections caused by A. baumannii. Here, we investigated the in vitro antimicrobial synergistic activities of several antimicrobial agent combinations against CoR A. baumannii. A total of 41 non-duplicate clinical isolates of CoR A. baumannii from a tertiary care hospital in Korea were prospectively collected from April 2012 to December 2014. As a control group, 41 carbapenem-resistant but colistin-susceptible (CoS) A. baumannii strains were also evaluated. Minimum inhibitory concentrations (MICs) of antimicrobial agents were determined by Etest in triplicate, and in vitro synergy tests were performed by the Etest MIC:MIC ratio method. Synergistic activity was determined as the sum of each antimicrobial agent's fractional inhibitory concentration evaluated (ΣFIC): synergy, ≤0.5; indifference, >0.5-4; and antagonism, >4. Synergistic activities were more frequently observed in the CoR group than the CoS group for combinations of colistin-rifampicin (80.5% vs. 14.6%, P< 0.0001), colistin-meropenem (85.4% vs. 4.9%, P< 0.0001), and colistin-imipenem (46.3% vs. 2.4%, P< 0.0001). Combination with rifampicin or meropenem lowered colistin MICs against CoR A. baumannii clinical isolates to the susceptible range (≤ 2 µg/mL) more frequently (61.0%, 25/41, both) than combination with imipenem (29.3%, 12/41). Clinical trials are needed to prove the in vivo efficacy of those antimicrobial combinations that exhibited significant in vitro antimicrobial synergistic effects against CoR A. baumannii.