Embryonic Stem Cells Lacking DNA Methyltransferases Differentiate into Neural Stem Cells that Are Defective in Self-Renewal

Background and Objectives@#DNA methyltransferases (Dnmts) play an important role in regulating DNA methylation during early developmental processes and cellular differentiation. In this study, we aimed to investigate the role of Dnmts in neural differentiation of embryonic stem cells (ESCs) and in maintenance of the resulting neural stem cells (NSCs). @*Methods@#and Results: We used three types of Dnmt knockout (KO) ESCs, including Dnmt1 KO, Dnmt3a/3b double KO (Dnmt3 DKO), and Dnmt1/3a/3b triple KO (Dnmt TKO), to investigate the role of Dnmts in neural differentiation of ESCs. All three types of Dnmt KO ESCs could form neural rosette and differentiate into NSCs in vitro. Interestingly, however, after passage three, Dnmt KO ESC-derived NSCs could not maintain their self-renewal and differentiated into neurons and glial cells. @*Conclusions@#Taken together, the data suggested that, although deficiency of Dnmts had no effect on the differentiation of ESCs into NSCs, the latter had defective maintenance, thereby indicating that Dnmts are crucial for self-renewal of NSCs.

Clinical impact of healthcare-associated acquisition in cirrhotic patients with community-onset spontaneous bacterial peritonitis

Background/Aims@#Healthcare-associated (HCA) infection is a recently suggested new category of community-onset infections. The implications of HCA infections in terms of diagnosis, treatment, and outcomes of spontaneous bacterial peritonitis (SBP) are not well understood. We sought to delineate the differences between community-acquired (CA) SBP and HCA SBP with specific interest in the antimicrobial resistance of causative microorganisms and outcomes. @*Methods@#We conducted a retrospective cohort study of all SBP episodes with positive ascitic culture and/or blood culture from June 2000 to August 2011. Community-onset SBP episodes were included when they occurred within 48 hours after admission and were classified as CA SBP and HCA SBP based on the predefined criteria. @*Results@#A total of 188 episodes of community-onset SBP were analyzed (65.4% HCA SBP and 34.6% CA SBP). HCA SBP had a higher resistance rate to third-generation cephalosporin (6.8% vs. 1.6%, p = 0.168). The overall 30-day mortality was similar between both groups (37.4% vs. 41.5%, p = 0.638). The independent risk factors for 30-day all-cause mortality in community-onset SBP included high Child-Pugh score, acute kidney injury, and resistance to third-generation cephalosporins; HCA infection was not associated. @*Conclusions@#Hepatic functional status, renal dysfunction, and third-generation cephalosporin resistant pathogens more adversely affected the outcome of cirrhotic patients with community-onset SBP rather than HCA infection. The higher rate of third-generation cephalosporin resistance was notable in HCA SBP, which will require a novel approach to empirical antibiotic treatment selection in this population.

Evaluation of a Carbapenem-Saving Strategy Using Empirical Combination Regimen of Piperacillin-Tazobactam and Amikacin in Hemato-Oncology Patients

We implemented a carbapenem-saving strategy in hemato-oncology patients from 2013, using an empirical combination of piperacillin-tazobactam and amikacin for high-risk hemato-oncology patients with febrile neutropenia, who remain hemodynamically unstable > 72 hours despite initial cefepime treatment. All-cause mortality was not different between the two periods (6.54 and 6.57 deaths per 1,000 person-day, P = 0.926). Group 2 carbapenem use significantly decreased after strategy implementation (78.43 vs. 67.43 monthly days of therapy, P = 0.018), while carbapenem-resistant gram-negative bacilli did not show meaningful changes during the study period. Our carbapenem-saving strategy could effectively suppress carbapenem use without an increase of overall mortality.

Reevaluation of the impact of methicillin-resistance on outcomes in patients with Staphylococcus aureus bacteremia and endocarditis

BACKGROUND/AIMS@#Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in hospitals, and has recently emerged in the community. The impact of methicillin-resistance on mortality and medical costs for patients with S. aureus bacteremia (SAB) requires reevaluation.@*METHODS@#We searched studies with SAB or endocarditis using electronic databases including Ovid-Medline, Embase-Medline, and Cochrane Library, as well as five local databases for published studies during the period January 2000 to September 2011.@*RESULTS@#A total of 2,841 studies were identified, 62 of which involved 17,563 adult subjects and were selected as eligible. A significant increase in overall mortality associated with MRSA, compared to that with methicillin-susceptible S. aureus (MSSA), was evidenced by an odds ratio (OR) of 1.95 (95% confidence interval [CI], 1.73 to 2.21; p < 0.01). In 13 endocarditis studies, MRSA increased the risk of mortality, with an OR of 2.65 (95% CI, 1.46 to 4.80). When three studies, which compared mortality rates between CA-MRSA and CA-MSSA, were combined, the risk of methicillin-resistance increased 3.23-fold compared to MSSA (95% CI, 1.25 to 8.34). The length of hospital stay in the MRSA group was 10 days longer than that in the MSSA group (95% CI, 3.36 to 16.70). Of six studies that reported medical costs, two were included in the analysis, which estimated medical costs to be $9,954.58 (95% CI, 8,951.99 to 10,957.17).@*CONCLUSIONS@#MRSA is still associated with increased mortality, longer hospital stays and medical costs, compared with MSSA in SAB in studies published since the year 2000.

Modern History of Tuberculosis in Korea

Tuberculosis has been a major public health threat in modern Korea. A few reports from the mid-1940s have demonstrated a high prevalence of latent and active tuberculosis infections. The high disease burden urged the newly established government to place a high priority on tuberculosis control. The government led a nationwide effort to control tuberculosis by building dedicated hospitals, conducting mass screening, providing technical and material support for microbiological diagnosis, administering Bacillus Calmette–Guérin vaccination, and improving appropriate antibiotic treatment through public health centers. Such concerted efforts resulted in a gradual decrease in the disease burden of tuberculosis, as demonstrated by National Tuberculosis Prevalence Surveys and notifiable disease statistics. While great progress has been made, new challenges - including an aging population, outbreaks in schools and healthcare facilities, and migration from high-prevalence countries - lie ahead. Here, we review the modern history of tuberculosis in Korea, focusing on epidemiology and public health policies.

Failure of Ciprofloxacin Therapy in the Treatment of Community-Acquired Acute Pyelonephritis caused by In-Vitro Susceptible Escherichia coli Strain Producing CTX-Type Extended-Spectrum β-Lactamase

While carbapenems are the drug of choice to treat extended-spectrum-β-lactamase (ESBL)-producing strains, some alternative carbapenem-sparing regimens are suggested for antibiotic stewardship. We experienced a case of ciprofloxacin treatment failure for acute pyelonephritis caused by an apparently susceptible Escherichia coli. A 71-year-old woman presented the emergency department with fever for 7 days and bilateral flank pain for 2 days. The laboratory results and abdominopelvic computed tomography finding were compatible with acute pyelonephritis. During 3-day ciprofloxacin therapy, the patient remained febrile with persistent bacteremia. After the change in antibiotics to ertapenem, the patient’s clinical course started to improve. ESBL-producing E. coli isolates were identified in all three consecutive blood samples. Pulsed-field gel electrophoresis (PFGE) patterns, serotypes, and sequence types showed the three isolates were derived from the identical strain. The isolates produced CTX-M-14 type ESBL belonging to the ST69 clonal group. Despite in vitro susceptibility, the failure was attributed to a gyrA point mutation encoding Ser83Leu within quinolone resistance-determining regions. This case suggests that ciprofloxacin should be used cautiously in the treatment of serious infections caused by ciprofloxacin-susceptible, ESBL-producing E. coli, even in acute pyelonephritis because in-vitro susceptibility tests could fail to detect certain genetic mutations.

Failure of Ciprofloxacin Therapy in the Treatment of Community-Acquired Acute Pyelonephritis caused by In-Vitro Susceptible Escherichia coli Strain Producing CTX-Type Extended-Spectrum β-Lactamase

While carbapenems are the drug of choice to treat extended-spectrum-β-lactamase (ESBL)-producing strains, some alternative carbapenem-sparing regimens are suggested for antibiotic stewardship. We experienced a case of ciprofloxacin treatment failure for acute pyelonephritis caused by an apparently susceptible Escherichia coli. A 71-year-old woman presented the emergency department with fever for 7 days and bilateral flank pain for 2 days. The laboratory results and abdominopelvic computed tomography finding were compatible with acute pyelonephritis. During 3-day ciprofloxacin therapy, the patient remained febrile with persistent bacteremia. After the change in antibiotics to ertapenem, the patient’s clinical course started to improve. ESBL-producing E. coli isolates were identified in all three consecutive blood samples. Pulsed-field gel electrophoresis (PFGE) patterns, serotypes, and sequence types showed the three isolates were derived from the identical strain. The isolates produced CTX-M-14 type ESBL belonging to the ST69 clonal group. Despite in vitro susceptibility, the failure was attributed to a gyrA point mutation encoding Ser83Leu within quinolone resistance-determining regions. This case suggests that ciprofloxacin should be used cautiously in the treatment of serious infections caused by ciprofloxacin-susceptible, ESBL-producing E. coli, even in acute pyelonephritis because in-vitro susceptibility tests could fail to detect certain genetic mutations.

Risk factors for poor prognosis in nosocomial infective endocarditis

BACKGROUND/AIMS@#The aim of our study was to compare the characteristics of nosocomial infective endocarditis (NIE) with community-acquired infective endocarditis (CIE) and to determine independent risk factors for in-hospital death.@*METHODS@#We retrospectively reviewed the medical records of 560 patients diagnosed with infective endocarditis. NIE was defined by a diagnosis made > 72 hours after hospital admission or within 2 months of hospital discharge.@*RESULTS@#Among the 560 cases reviewed, 121 were classified as NIE. Compared with patients with CIE, patients with NIE were older (mean ± SD, 51.30±18.01 vs. 59.76±14.87, p < 0.001). The in-hospital death rate of the NIE group was much higher than that of the CIE group (27.3% vs. 5.9%, p < 0.001). More patients with NIE had central intravenous catheters, and were undergoing hemodialysis (p < 0.001). Methicillin-resistant Staphylococcus aureus (MRSA) was the most common causal microorganism of NIE, and MRSA (p < 0.001) and fungus (p = 0.002) were more common in NIE compared with CIE. On multiple analysis, age, liver cirrhosis, cancer chemotherapy, central intravenous catheter, hemodialysis, and genitourinary tract manipulation were independent clinical risk factors for NIE. Among the patients with NIE, 33 died during their hospital admission. The independent risk factors for in-hospital death were older age (adjusted odds ratio [OR], 1.04; 95% confidence interval [CI], 1.01 to 1.07; p = 0.037) and chemotherapy for malignancy (adjusted OR, 3.89; 95% CI, 1.18 to 12.87; p = 0.026).@*CONCLUSIONS@#Because of the considerable incidence of NIE and its poor prognosis, we should pay attention to early diagnosis and active management of NIE, especially for older patients and patients receiving chemotherapy.

Importance of Specimen Type and Quality in Diagnosing Middle East Respiratory Syndrome

No abstract available.

Emergence of Community-Genotype Methicillin-Resistant Staphylococcus aureus in Korean Hospitals: Clinical Characteristics of Nosocomial Infections by Community-Genotype Strain

BACKGROUND: As community-genotype methicillin-resistant Staphylococcus aureus (MRSA) strains spread into hospitals, the genotypes of the MRSA strains causing hospital-acquired (HA) infections have become more diverse. We describe clinical characteristics of nosocomial MRSA infections by a community-genotype of sequence type (ST) 72. MATERIALS AND METHODS: A case-control study was designed among patients with HA-MRSA infections. Forty patients with infections caused by ST72-MRSA SCCmec type IV were selected as cases. Cases were matched to the controls with 106 patients infected with ST5/ST239 MRSA, which are representative hospital genotypes in Korea. RESULTS: Patients infected with ST72 isolates were younger than those with ST5/ST239 isolates. Female gender predominated among ST72 MRSA group compared to ST5/ST239 MRSA group. Solid tumor was a more frequent underlying disease in MRSA infections by ST72 isolates, whereas underlying renal, lung, heart, and neurologic diseases were more frequently found in those by ST5/ST239 isolates. The most common type of infection was pneumonia in both ST72 and ST5/ST239 groups (45.0% vs. 51.9%), followed by skin and soft tissue infection (SSTI). Female gender and underlying solid tumor were identified to be independent predictors for MRSA infections by ST72 isolates. All-cause mortality rates (20.0% vs. 30.2%) were not different between the groups. CONCLUSION: A community-genotype MRSA, ST72 isolate has emerged as a nosocomial pathogen presenting as hospital-acquired pneumonia and SSTI. Although differences in underlying disorders were found, the distribution of infection type and mortality rate did not differ between the groups.

Differential Cell Count and CRP Level in Blood as Predictors for Middle East Respiratory Syndrome Coronavirus Infection in Acute Febrile Patients during Nosocomial Outbreak

A case-control study was performed to identify clinical predictors for Middle East respiratory syndrome coronavirus (MERS-CoV) infection among patients with acute febrile illness during the nosocomial outbreak. Patients with MERS-CoV were more likely to have monocytosis with normal white blood cell (WBC) count and lower C-reactive protein (CRP) level. Simple laboratory data such as complete blood counts (CBC) with differential count could be a useful marker for the prediction of MERS and triage at the initial presentation of acute febrile patients in outbreak setting.

Risk factors and molecular epidemiology of community-onset, multidrug resistance extended-spectrum β-lactamase-producing Escherichia coli infections

BACKGROUND/AIMS: Although multidrug resistance (MDR) among extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) poses significant therapeutic challenges, little is known regarding the risk factors and epidemiology of community-onset MDR-ESBL-EC infections. We performed this study to investigate risk factors and the molecular epidemiology of community-onset MDR-ESBL-EC infections. METHODS: We conducted a case-control-control study of community-onset infections. MDR-ESBL-EC was defined as ESBL-EC that demonstrated in vitro resistance to trimethoprim-sulfamethoxazole, fluoroquinolones (FQs), and gentamicin. Patients with MDR-ESBL-EC infections were designated as case patients. A control group I (CG I) patient was defined as a person whose clinical sample yielded ESBL-EC that did not meet the criteria for MDR. A control group II (CG II) patient was defined as a patient with a non-ESBL-EC infection. RESULTS: Of 108 patients with ESBL-EC infections, 30 cases (27.8%) were due to MDR-ESBL-EC. Compared with CG I, prior use of FQs (odds ratio [OR], 3.16; 95% confidence interval [CI], 1.11 to 8.98) and immunosuppressant use (OR, 10.47; 95% CI, 1.07 to 102.57) were significantly associated with MDR-ESBL-EC. Compared with CG II, prior use of FQs (OR, 15.53; 95% CI, 2.86 to 84.27) and healthcare-associated infection (OR, 5.98; 95% CI, 2.26 to 15.86) were significantly associated with MDR-ESBL-EC. CTX-M-15 was the most common in MDR-ESBL-EC infections (59.1% [13/22]), while CTX-M-14 was the most common in non-MDR-ESBL-EC infections (41.6% [32/77]). CTX-M-15 was significantly associated with MDR-ESBL-EC (59.1% vs. 32.5%, p = 0.028). Pulsed-field gel electrophoresis showed clonal diversity of MDR-ESBL-EC isolates. CONCLUSIONS: The emergence of strains of MDR-ESBL-EC in the community poses an important new public health threat. More information on the emergence and transmission of these strains will be necessary in order to prevent their spread.

Diagnostic yield of computed tomography-guided bone biopsy and clinical outcomes of tuberculous and pyogenic spondylitis

BACKGROUND/AIMS: This study aimed to evaluate the efficacy of computed tomography (CT)-guided bone biopsy for the diagnosis of spinal infection and compared the clinical outcomes between tuberculous and pyogenic spinal infections. METHODS: The retrospective cohort study included patients who received CT-guided bone biopsy at a tertiary hospital over the 13 years. RESULTS: Among 100 patients, 67 had pyogenic spondylitis and 33 had tuberculous spondylitis. Pathogens were isolated from bone specimens obtained by CT-guided biopsy in 42 cases, with diagnostic yields of 61% (20/33) for tuberculous spondylitis and 33% (22/67) for pyogenic spondylitis. For 36 culture-proven pyogenic cases, Staphylococcus aureus was the most commonly isolated organism. Patients with pyogenic spondylitis more frequently presented with fever accompanied by an increase in inflammatory markers than did those with tuberculosis. Among all patients who underwent surgery, the incidence of late surgery performed one month after diagnosis was higher in patients with tuberculous infection (56.3%) than in those with pyogenic disease (23.3%, p = 0.026). CONCLUSIONS: Results obtained by CT-guided bone biopsy contributed to prompt diagnoses of spinal infections, especially those caused by tuberculosis. Despite administration of anti-tuberculous agents, patients with tuberculous spondylitis showed an increased tendency to undergo late surgery.

Current Situation of Antimicrobial Resistance and Genetic Differences in Stenotrophomonas maltophilia Complex Isolates by Multilocus Variable Number of Tandem Repeat Analysis

BACKGROUND: Stenotrophomonas maltophilia is one of several opportunistic pathogens of growing significance. Several studies on the molecular epidemiology of S. maltophilia have shown clinical isolates to be genetically diverse. MATERIALS AND METHODS: A total of 121 clinical isolates tentatively identified as S. malophilia from seven tertiary-care hospitals in Korea from 2007 to 2011 were included. Species and groups were identified using partial gyrB gene sequences and antimicrobial susceptibility testing was performed using a broth microdilution method. Multi locus variable number of tandem repeat analysis (MLVA) surveys are used for subtyping. RESULTS: Based on partial gyrB gene sequences, 118 isolates were identified as belonging to the S. maltophilia complex. For all S. maltophilia isolates, the resistance rates to trimethoprime-sulfamethoxazole (TMP/SMX) and levofloxacin were the highest (both, 30.5%). Resistance rate to ceftazidime was 28.0%. 11.0% and 11.9% of 118 S. maltophilia isolates displayed resistance to piperacillin/tazobactam and tigecycline, respectively. Clade 1 and Clade 2 were definitely distinguished from the data of MLVA with amplification of loci. All 118 isolates were classified into several clusters as its identification. CONCLUSION: Because of high resistance rates to TMP/SMX and levofloxacin, the clinical laboratory department should consider providing the data about other antimicrobial agents and treatment of S. maltophilia infections with a combination of antimicrobials can be considered in the current practice. The MLVA evaluated in this study provides a fast, portable, relatively low cost genotyping method that can be employed in genotypic linkage or transmission networks comparing to analysis of the gyrB gene.

Nasal Deformity Due to Tuberculous Chondritis

Tuberculosis (TB) is a common disease worldwide. However, nasal TB is quite rare, and the diagnosis of nasal TB requires a high index of suspicion. The most common symptoms of this unusual presentation are nasal obstruction and nasal discharge. We present a case of nasal TB with involvement of the hard palate presenting with a chronically progressive nasal deformity and ulceration of the hard palate. A biopsy confirmed the diagnosis, and medication for TB was started and the lesions resolved. When a patient presents with chronic ulcerative lesions that do not respond to antibiotic treatment, TB should be included in the differential diagnosis. Biopsy of the lesion can aid in the confirmation of the diagnosis.

Native valve endocarditis due to extended spectrum beta-lactamase producing Klebsiella pneumoniae

No abstract available.

Cervical Lymphadenitis Caused by Group D Non-typhoidal Salmonella Associated with Concomitant Lymphoma

Non-typhoidal Salmonella species are important foodborne pathogens that can cause gastroenteritis, bacteremia, and subsequent focal infections. Non-typhoidal salmonellosis is problematic, particularly in immunocompromised hosts. Any anatomical site can be affected by this pathogen via hematogenous seeding and may develop local infections. However, cervical lymphadenitis caused by non-typhoidal Salmonella species is rarely reported. Herein, we have reported a case of cervical lymphadenitis caused by group D non-typhoidal Salmonella associated with lymphoma.

A third case of USA300 community-associated methicillin-resistant Staphylococcus aureus infection in Korea

No abstract available.

Clinical and Molecular Epidemiology of Community-Onset Bacteremia Caused by Extended-Spectrum beta-Lactamase-Producing Escherichia coli over a 6-Year Period

Although extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) has emerged as a significant community-acquired pathogen, there is little epidemiological information regarding community-onset bacteremia due to ESBL-EC. A retrospective observational study from 2006 through 2011 was performed to evaluate the epidemiology of community-onset bacteremia caused by ESBL-EC. In a six-year period, the proportion of ESBL-EC responsible for causing community-onset bacteremia had increased significantly, from 3.6% in 2006 to 14.3%, in 2011. Of the 97 clinically evaluable cases with ESBL-EC bacteremia, 32 (33.0%) were further classified as healthcare-associated infections. The most common site of infection was urinary tract infection (n=35, 36.1%), followed by biliary tract infections (n=29, 29.9%). Of the 103 ESBL-EC isolates, 43 (41.7%) produced CTX-M-14 and 36 (35.0%) produced CTX-M-15. In the multilocus sequence typing (MLST) analysis of 76 isolates with CTX-M-14 or -15 type ESBLs, the most prevalent sequence type (ST) was ST131 (n=15, 19.7%), followed by ST405 (n=12, 15.8%) and ST648 (n=8, 10.5%). No significant differences in clinical features were found in the ST131 group versus the other group. These findings suggest that epidemic ESBL-EC clones such as CTX-M-14 or -15 type ESBLs and ST131 have disseminated in community-onset infections, even in bloodstream infections, which are the most serious type of infection.

First Imported Case of Skin Infection Caused by PVL-positive ST30 Community-Associated Methicillin-Resistant Staphylococcus aureus Clone in a Returning Korean Traveler from the Philippines

Although pandemic community-associated (CA-) methicillin-resistant Staphylococcus aureus (MRSA) ST30 clone has successfully spread into many Asian countries, there has been no case in Korea. We report the first imported case of infection caused by this clone in a Korean traveler returning from the Philippines. A previously healthy 30-yr-old Korean woman developed a buttock carbuncle while traveling in the Philippines. After coming back to Korea, oral cephalosporin was given by a primary physician without any improvement. Abscess was drained and MRSA strain isolated from her carbuncle was molecularly characterized and it was confirmed as ST30-MRSA-IV. She was successfully treated with vancomycin and surgery. Frequent international travel and migration have increased the risk of international spread of CA-MRSA clones. The efforts to understand the changing epidemiology of CA-MRSA should be continued, and we should raise suspicion of CA-MRSA infection in travelers with skin infections returning from CA-MRSA-endemic countries.