Impact of Molecular Epidemiology and Reduced Susceptibility to Glycopeptides and Daptomycin on Outcomes of Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia

Background

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia was associated with high mortality, but the risk factors associated with mortality remain controversial.

Methods

A retrospective cohort study was designed. All patients with MRSA bacteremia admitted were screened and collected for their clinical presentations and laboratory characteristics. Minimum inhibitory concentration (MIC) and staphylococcal cassette chromosome mec (SCCmec) type of bacterial isolates were determined. Risk factors for mortality were analyzed.

Results

Most MRSA isolates from the 189 enrolled patients showed reduced susceptibility to antibiotics, including MIC of vancomycin ≥ 1.5 mg/L (79.9%), teicoplanin ≥ 2 mg/L (86.2%), daptomycin ≥ 0.38 mg/L (73.0%) and linezolid ≥ 1.5 mg/L (64.0%). MRSA with vancomycin MIC ≥ 1.5 mg/L and inappropriate initial therapy were the two most important risk factors for mortality (both P < 0.05; odds ratio = 7.88 and 6.78). Hospital-associated MRSA (HA-MRSA), carrying SCCmec type I, II, or III, was associated with reduced susceptibility to vancomycin, teicoplanin or daptomycin and also with higher attributable mortality (all P < 0.05). Creeping vancomycin MIC was linked to higher MIC of teicoplanin and daptomycin (both P < 0.001), but not linezolid (P = 0.759).

Conclusions

Giving empirical broad-spectrum antibiotics for at least 5 days to treat catheter-related infections, pneumonia, soft tissue infection and other infections was the most important risk factor for acquiring subsequent HA-MRSA infection. Choice of effective anti-MRSA agents for treating MRSA bacteremia should be based on MIC of vancomycin, teicoplanin and daptomycin. Initiation of an effective anti-MRSA agent without elevated MIC in 2 days is crucial for reducing mortality.

Pneumococcal disease and use of pneumococcal vaccines in Taiwan

The use of pneumococcal vaccine plays an important role for prevention of invasive pneumococcal disease (IPD). However, introducing the pneumococcal vaccine into the national immunization program (NIP) is complex and costly. The strategy of progressively integrating the pneumococcal conjugate vaccine (PCV) into the NIP in Taiwan provides valuable experience for policy makers. The 7-valent PCV (PCV7) was first available in Taiwan in late 2005. PCV7 was first provided free to children with underlying diseases, those in vulnerable socioeconomic status, and those with inadequate health care resources. The catch-up immunization program with the 13-valent PCV was launched in 2013 and the national pneumococcal immunization program was implemented in 2015. Children aged 2-5 years had the highest incidence of IPD among pediatric population in Taiwan. Although the incidence of IPD caused by PCV7 serotypes has declined, the overall incidence of IPD remained high in the context of PCV7 use in the private sector. A surge of IPD caused by serotype 19A occurred, accounting for 53.6% of IPD cases among children aged ≤ 5 years in 2011-2012. After the implementation of the national pneumococcal immunization program, serogroup 15 has become the leading serogroup for IPD in children. Continued surveillance is necessary to monitor the serotype epidemiology in Taiwan.

High prevalence and antimicrobial resistance of urinary tract infection isolates in febrile young children without localizing signs in Taiwan

BACKGROUND

Antimicrobial susceptibility and prevalence of pediatric urinary tract infection (UTI) is very useful for pediatricians in selecting effective antibiotics in time to improve outcomes in patients. This study aimed to determine the prevalence rate, bacterial distribution, and antimicrobial susceptibility of UTI in febrile young children at a teaching hospital in northern Taiwan.

METHODS

From January 2011 to December 2011, all urinary isolates from suspected cases of UTI in febrile young children aged from 1 day to 36 months visiting the Pediatric Emergency Room of Chang Gung Children's Hospital, Taoyuan, Taiwan were identified by conventional methods. Antibiotic susceptibility was determined according to the Clinical and Laboratory Standards Institute.

RESULTS

A total of 5470 (78%) from 7009 eligible children were enrolled in the study, and 619 (11.3%) had a diagnosis of UTI. The most prevalent bacterium was Escherichia coli (68%) followed by Klebsiella pneumoniae (8.1%) and Proteus mirabilis (6.8%). Ampicillin, piperacillin, and trimethoprim-sulfamethoxazole (TMP-SMX) showed a higher resistance rate in the three predominant bacteria. All tested bacteria showed higher resistance to ampicillin (79.3%) and TMP-SMX (44.1%), and lower resistance to cefazolin (17.7%) and gentamicin (13.0%). Fourteen percent of the isolates produced extended spectrum β-lactamase (ESBL), among which 93.33% were E. coli isolates.

CONCLUSION

The overall prevalence of UTI in this study was higher than previously reported in febrile children. Higher antimicrobial resistance was found in ampicillin and TMP-SMX. Among commonly used antibiotics, cefazolin and gentamicin are recommended to treat UTI in febrile children aged < 3 years without localizing signs.

Pathogenic bacterial nasopharyngeal colonization and its impact on respiratory diseases in the first year of life: the PATCH Birth Cohort Study

BACKGROUND

For acute respiratory diseases caused by bacteria, colonization in the respiratory tracts is often the first sign, although nasopharynx is the major source of secretions containing pathogens. To understand the pathogenesis of respiratory tract diseases, it is important to analyze the establishment of nasopharyngeal bacterial colonization.

METHODS

Infants with nasopharyngeal swabs were examined at the age of 1, 2, 4, 6 and 12 months for the detection of pathogens, including Streptococcus pneumoniae, Hemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes and Staphylococcus aureus. The methods used for detection were bacterial culture and multiplex polymerase chain reaction.

RESULTS

From January 2012 to August 2013, a total of 320 neonates were enrolled, and 120 of them completed the first 12-month study. Staphylococcus aureus was the most common pathogen at all 5 time points while the rates declined; in contrast, the other 4 increased during the first year of life. Of our series, the multiplex polymerase chain reaction detection rates were higher than those of bacterial culture. More than 50% of Staphylococcus aureus was methicillin-resistant, and the trend decreased in the same period. In the analysis of factors associated with the development of infant wheeze, infants with maternal atopy [odds ratio (OR): 3.26; 95% confidence interval (CI): 1.20-8.88; P = 0.02] and pneumococcal colonization (OR: 15.64; 95% CI: 3.25-75.35; P = 0.001) had higher rates of wheeze.

CONCLUSIONS

Bacterial interactions may result in differing pathogen prevalence in the first year of life. In addition, nasopharyngeal pneumococcal colonization may have an effect on the risk of infant wheeze. The result could help clinicians to clarify the relation between bacterial colonization and respiratory illnesses in infancy.

Emergence in Taiwan of novel imipenem-resistant Acinetobacter baumannii ST455 causing bloodstream infection in critical patients

BACKGROUND

Acinetobacter baumannii is one of the most important nosocomial pathogens worldwide. This study aimed to use multilocus sequence typing (MLST) for the epidemiological surveillance of A. baumannii isolates in Taiwan and analyze the clinical presentations and patients' outcome.

METHODS

MLST according to both Bartual's PubMLST and Pasteur's MLST schemes was applied to characterize bloodstream imipenem-resistant A. baumannii (IRAB) infection in intensive care units in a medical center. A total of 39 clinical IRAB bloodstream isolates in 2010 were enrolled. We also collected 13 imipenem-susceptible A. baumannii (ISAB) bloodstream isolates and 30 clinical sputum isolates (24 IRAB and 6 ISAB) for comparison. Clinical presentations and outcome of the patients were analyzed.

RESULTS

We found that infection by ST455(B)/ST2(P) and inappropriate initial therapy were statistically significant risk factors for mortality. More than one-third of the IRAB isolates belonged to ST455(B)/ST2(P). Most ST455(B)/ST2(P) (80%) carried ISAba1-blaOXA-23, including 10 (66.7%) with Tn2006 (ISAba1-blaOXA-23-ISAba1) in an AbaR4-type resistance island. ST455(B)/ST2(P) appears to evolve from ST208(B)/ST2(P) of clonal complex (CC) 92(B)/CC2(P). In this hospital-based study, A. baumannii ST455 accounted for 38.5% of IRAB bacteremia, with a high mortality of 86.7%. Approximately 85% of ST455(B)/ST2(P)bacteremia had a primary source of ventilation-associated pneumonia.

CONCLUSION

We report the emergence in Taiwan of IRAB ST455(B)/ST2(P), which is the current predominant clone of IRAB in our hospital and has been causing bacteremia with high mortality in critical patients.

Emergence in Taiwan of novel imipenem-resistant Acinetobacter baumannii ST455 causing bloodstream infection in critical patients

BACKGROUND

Acinetobacter baumannii is one of the most important noscomial pathogens worldwide. The study aimed to use multilocus sequence typing (MLST) for epidemiological surveillance of A. baumannii isolates in Taiwan and analyze the clinical presentations and patients' outcomes.

METHODS

MLST according to both Bartual's PubMLST and Pasteur's MLST schemes was applied to characterize bloodstream imipenem-resistant A. baumannii (IRAB) infection in intensive care units in a medical center. A total of 39 clinical IRAB bloodstream isolates in 2010 were enrolled. We also collected 13 imipenem-susceptible A. baumannii bloodstream isolates and 30 clinical sputum isolates (24 IRAB and 6 imipenem-susceptible A. baumannii) for comparison. Clinical presentations and outcome of the patients were analyzed.

RESULTS

We found that infection by ST455B/ST2P and inappropriate initial therapy were statistically significant risk factors for mortality. More than one third of the IRAB isolates belonged to ST455B/ST2P. Most ST455B/ST2P (80%) carried ISAba1-blaOXA-23, including 10 (66.7%) with Tn2006 (ISAba1-blaOXA-23-ISAba1) in an AbaR4-type resistance island. ST455B/ST2P appears to evolve from ST208B/ST2P of clonal complex (CC) 92B/CC2P. In this hospital-based study, A. baumannii ST455 accounted for 38.5% of IRAB bacteremia, with a high mortality of 86.7%. Approximately 85% of ST455B/ST2P bacteremia had a primary source of ventilation-associated pneumonia.

CONCLUSION

We report the emergence in Taiwan of IRAB ST455B/ST2P, which is the current predominant clone of IRAB in our hospital and has been causing bacteremia with high mortality in critical patients.

Emergence in Taiwan of novel norovirus GII.4 variants causing acute gastroenteritis and intestinal haemorrhage in children

Norovirus is the leading cause of viral gastroenteritis globally. Norovirus genotype GII.4 is responsible for the majority of outbreaks, but new variants are continuously emerging. The objective of the study was to delineate the clinical manifestations and complications associated with these new norovirus GII.4 variants in children. We investigated norovirus infections from the community outbreak in October 2011-September 2012 and an earlier outbreak in 2006-2007, in northern Taiwan. Norovirus genotypes and their variants were validated using molecular methods. A norovirus outbreak started in mid-2011 and continued through 2012 in northern Taiwan. Hospitalized children infected by norovirus in 2012 showed a significantly higher incidence of intestinal haemorrhage, as indicated by grossly bloody faeces (P=0.012) and occult blood in faeces (P < 0.001), and also presented with more high fever >39 °C (P < 0.001), fever >38.5 °C (P < 0.001) and fever of any temperature >38 °C (P < 0.001), compared with children hospitalized in 2006-2007. Analysis of 20 near-full-length genome sequences indicated an emergence of GII.4 2012 variants in 2011-2012. Circulating noroviruses can be divided into two clusters: GII.4 2012a, which is identical to the newly reported strain GII.4 Sydney 2012, and GII.4 2012b, which is close to GII.4 2006b, the earlier predominant strain. The emerging new variants of norovirus GII.4 caused a distinct clinical syndrome of acute gastroenteritis with severe fever and a high rate of intestinal haemorrhage in children. The genetic diversity associated with changing clinical manifestations poses major obstacles to norovirus control.

Effects of an education program on intensive care unit nurses' attitudes and behavioral intentions to advocate deceased donor organ donation

INTRODUCTION

Organ shortage limits the application of organ transplantation. The attitudes of intensive care unit (ICU) staff play an important role in organ advocating. The effects of an education program for ICU nurses on organ advocating were uncertain. The purpose of this study was to explore the effects of an education program based on the Theory of Planned Behavior (TPB) on ICU nurses' attitudes and behavioral intentions to advocate deceased organ donation.

METHODS

Participants were recruited from 3 different ICU units in medical centers and were randomly assigned to either an experimental group (n = 61) or a control group (n = 62). The nurses in the experimental group received comprehensive education programs, and the control groups received a brochure only. The outcome parameters were measured by questionnaires at 3 different time points of pretest, posttests immediately after education, and 2 months later.

RESULTS

Before education, there was no difference in attitude and behavior intentions between the control and experimental groups. After TPB training, the nurses significantly changed their attitudes and behavior intentions on organ advocating, both immediately (P < .01) and 2 months after the education program (P < .01). In addition, multivariate analysis indicated that TPB training is significantly associated with the change of attitude (P < .01) and behavior intention (P < .05) of organ donation advocacy.

CONCLUSIONS

TPB education programs enhanced the ICU nurses' attitudes and behavioral intentions on advocating organ donation. Repeated education is advised to increase the participation of ICU nurses on organ advocacy.

Application of next-generation sequencing to study ascitic microbiome in cirrhotic patients with or without spontaneous bacterial peritonitis

BACKGROUND

Spontaneous bacterial peritonitis is an important cause of morbidity and mortality in cirrhotic patients with ascites. The key step in the pathogenesis of spontaneous bacterial peritonitis is bacterial translocation from intestinal lumen to mesenteric lymph nodes, and from there to the systemic circulation and ascitic fluid. We aimed to study the ascitic microbiota of cirrhotic patients with or without spontaneous bacterial peritonitis.

METHODS

Both the 16S polymerase chain reaction approach and the whole genome shotgun approach were adopted for the next-generation sequencing technology. We compared the results derived from the two methods.

RESULTS

The bacterial culture-negative ascites in cirrhotic patients, which even failed for amplification of 16S ribosomal DNA, were found to contain much less bacterial DNA than the culture-positive ones, indicating that the paucity of bacteria, instead of the difficulty of bacterial culture, was possibly the main reason for negative culture result of the ascites. Escherichia coli was the predominant species in all samples, and the bacteria of low abundance were also identified by the next-generation sequencing technology.

CONCLUSION

Whole genome shotgun-based next-generation sequencing is an appropriate method for depicting the microbiome of ascites or of other specimens with a low abundance of bacterial DNA.

Influence of repeated infusion of capsaicin-contained red pepper sauce on esophageal secondary peristalsis in humans

BACKGROUND

The transient receptor potential vanilloid 1 has been implicated as a target mediator for heartburn perception and modulation of esophageal secondary peristalsis. Our aim was to determine the effect of repeated esophageal infusion of capsaicin-contained red pepper sauce on heartburn perception and secondary peristalsis in healthy adults.

METHODS

Secondary peristalsis was performed with mid-esophageal injections of air in 15 healthy adults. Two separate protocols including esophageal infusion with saline and capsaicin-contained red pepper sauce and 2 consecutive sessions of capsaicin-contained red pepper sauce were randomly performed.

KEY RESULTS

After repeated infusion of capsaicin-contained red pepper sauce, the threshold volume to activate secondary peristalsis was significantly increased during slow (p < 0.001) and rapid air injections (p = 0.004). Acute infusion of capsaicin-contained red pepper sauce enhanced heartburn perception (p < 0.001), but the intensity of heartburn perception was significantly reduced after repeated capsaicin-contained red pepper sauce infusion (p = 0.007). Acute infusion of capsaicin-contained red pepper sauce significantly increased pressure wave amplitudes of distal esophagus during slow (p = 0.003) and rapid air injections (p = 0.01), but repeated infusion of capsaicin-contained red pepper sauce significantly decreased pressure wave amplitude of distal esophagus during slow (p = 0.0005) and rapid air injections (p = 0.003).

CONCLUSIONS & INFERENCES

Repeated esophageal infusion of capsaicin appears to attenuate heartburn perception and inhibit distension-induced secondary peristalsis in healthy adults. These results suggest capsaicin-sensitive afferents in modulating sensorimotor function of secondary peristalsis in human esophagus.

Carbapenem-resistant-only Pseudomonas aeruginosa infection in patients formerly infected by carbapenem-susceptible strains

Pseudomonas aeruginosa isolates that were initially carbapenem-susceptible and later became selective carbapenem-resistant following antimicrobial therapy were identified from individual cases during the same hospitalisation. Cross-resistance to other β-lactams was not found and their susceptibilities remained identical in consecutive isolates. Real-time quantitative reverse transcription PCR was performed to investigate the role of OprD, an outer membrane protein regulating the entry of carbapenems, in the appearance of carbapenem-resistant-only P. aeruginosa (CROPA). Fifteen paired isolates of carbapenem-susceptible P. aeruginosa (CS-PA) and CROPA were identified. All of the cases had carbapenem exposure history within 1 month before the appearance of CROPA (mean 10 days). Reduced OprD expression was found in 93% (14/15) of the isolates, suggesting that oprD inactivation was the major contributor to selective carbapenem resistance. Of the 14 cases with CROPA due to oprD mutation, 71% (10/14) were persistent infection, as genotype analysis revealed that their paired strains were isogenic; 29% (4/14) represented re-infections as they were heterogenic, suggesting that oprD-deficient CROPA existed in the hospital and that carbapenem selective pressure promoted its spread to patients. We conclude that CROPA may occur soon after the use of carbapenems to treat CS-PA infections and that oprD mutation is the major mechanism of resistance in CROPA. Restriction of empirical use of carbapenems by antibiotic stewardship is important to halt the occurrence of CROPA.

Evaluation of Gram-negative bacterial infection by a stable and conjugative bioluminescence plasmid in a mouse model

Background

The green fluorescence protein (GFP)-associated fluorescence method and the luciferase-associated bioluminescence method are the two major methods for IVIS imaging system to investigate the bacterial infection in animal models. The aim of this study was to evaluate the infection route of Gram-negative bacteria carrying a stable and broad range of conjugative bioluminescence plasmid pSE-Lux1 in a mouse model.

Results

Both encapsulated and non-encapsulated Gram-negative bacteria were used as hosts to evaluate conjugation efficiency and plasmid stability of pSE-Lux1, a recombinant of pSE34 and luxABCDE operon. The plasmid conjugation efficiencies of pSE-Lux1 ranged from 10⁻³ to 10⁻⁷ in various Gram-negative bacteria. Plasmid pSE-Lux1 maintained in Escherichia coli, Klebsiella pneumoniae, and Salmonella enterica serovars Choleraesues (abbreviated S. Choleraesuis) and Typhimurium (S. Typhimurium), than in Acinetobacter baumannii and Serratia marcescens, was shown to be of better stability for at least four days. To investigate systemic bacterial infections, K. pneumoniae strain CG354 was intravenously injected, and then was clearly observed to be non-pathogenic to Balb/c mice for a long-term bioluminescence monitoring for 6 days. For examining dynamic distributions of gastrointestinal tract infection, the invasion protein SipB-deficient mutant OU5045△sipB and OU5046△sipB of S. serovar Typhimurium constructed in this study, compared to wild-type strain OU5045 and its virulence plasmid-less strain OU5046, were of less virulence to mice.

Conclusions

This is the first study to evaluate the conjugative and stable bioluminescence vehicle system of pSE-Lux1 in a wide range of Gram-negative bacteria, a system that can provide a useful reporter approach to trace systemic and gastrointestinal bacterial infections in a mouse model.

Step terrace tuned anisotropic transport properties of highly epitaxial LaBaCo2O5.5+δ thin films on vicinal SrTiO3 substrates

Highly epitaxial LaBaCo2O5.5+δ (LBCO) thin films were grown on different miscut (001) SrTiO3 substrates (miscut angle of 0.5°, 3.0°, and 5.0°) to study the substrate surface step terrace effect on the in-plane electrical transport properties. The microstructure studies by X-ray diffraction and transmission electron microscopy indicate that the as-grown films are A-site disordered cubic perovskite structures with the c-axis highly oriented along the film growth direction. The four-probe scanning tunneling microscopy (STM) studies show that the LBCO thin films grown on the vicinal SrTiO3 substrates have a typical semiconductor behavior with the substrate surface terrace step inducing anisotropic electronic transport properties. These results indicate that in highly epitaxial thin films the surface terrace step induced local strains can play an important role in controlling the electronic transport properties and the anisotropic nature.

Clinical, microbiologic, and outcome analysis of mycotic aortic aneurysm: the role of endovascular repair

BACKGROUND

Mycotic aortic aneurysm (MAA) is an infrequent but devastating form of vascular disease.

METHODS

We conducted a retrospective cohort study at a major medical center to identify independent risk factors for MAA and to provide opinions about treating it. The study population consisted of 43 patients who had had 44 MAAs over a period of 15 y.

RESULTS

All of the patients had positive blood cultures, radiologic findings typical of MAA, and clinical signs of infection (leukocytosis, fever, and elevated C-reactive protein). The mean age of the patients was 63.8±10.6 y and the mean period of their follow up was 35.7±39.3 mo. Twenty-nine patients with MAAs underwent traditional open surgery, 11 others received endovascular stent grafts, and four MAAs were managed conservatively. The most frequent causative pathogens were Salmonella (36/44 patients [81.8%]), in whom organisms of Salmonella serogroup C (consisting mainly of S. choleraesuis) were identified in 14 patients, organisms of Salmonella serogroup D were identified in 13 patients, and species without serogroup information were identified in nine patients. The overall mortality in the study population was 43.2% (with an aneurysm-related mortality of 18.2%, surgically related mortality of 13.6%, and in-hospital mortality of 22.7%).

CONCLUSIONS

Shock is a risk factor for operative mortality. Misdiagnosis and treatment of MAA as low back pain, co-existing connective-tissue disease such as systemic lupus erythematosus and rheumatoid arthritis, and Salmonella serogroup C-associated bacteremia are risk factors for aneurysm-related death. Endovascular repair should be considered as an alternative option to the open repair of MAA.

The acoustic radiation force impulse elastography evaluation of liver fibrosis in posttransplantation dysfunction of living donor liver transplantation

BACKGROUND

The acoustic radiation force impulse elastography (ARFI) is a new technology of elastography integrated into B-mode ultrasonography. It has been a reliable method to evaluate liver fibrosis of chronic liver disease in recent years, but less applied in the posttransplantation liver. The aim of the study was to evaluate liver fibrosis by the ARFI with correlation of pathological stages in living donor liver transplantation (LDLT).

MATERIALS AND METHODS

From August 2010 to August 2012, there were 57 LDLT patients with liver biopsy (LB) due to posttransplantation dysfunction; all patients also received posttransplantation ARFI liver stiffness measurement (LSM) after transplantation for liver fibrosis staging. The ARFI elastography was performed using a Siemens Acuson S2000 ultrasound system with 4V1 transducers (Acusion, Siemens Medical Systems Co. Ltd. Erlangen, Germany). The ARFI LSM value was presented by shear wave velocity (SWV, m/s). The fibrosis staging as F0 to F4 was in accordance with the Metavir scoring system.

RESULTS

A total of 57 patients had both posttransplantation LB and effective ARFI fibrosis staging for correlation. The ARFI LSM value increased with severity of liver fibrosis and had significant linear correlation with the results of histological fibrosis staging. The ARFI LSM sensitivities (Se), specificities (Sp), and cutoff values based on receiver-operator characteristic curve were F0: 0.75 m/s (Se: 93.8%, Sp: 4%), F1: 1.06 m/s (Se: 95.5%, Sp: 25.7%), F2: 1.81 m/s (Se: 50%, Sp: 83.6%) and F3: 2.33 m/s (Se: 100%, Sp: 92.9%). Predictive value of ARFI LSM reported a significant difference between early fibrosis stage (F0-F1) and advanced fibrosis stage (F ≧ 2) (P < .05).

CONCLUSION

In this study, ARFI demonstrated a strong linear correlation and severity of liver fibrosis with LB pathologic staging. ARFI can be an alternative and compensatory method for frequent LB in the posttransplantation liver.

Interface effects on the electronic transport properties in highly epitaxial LaBaCo2O(5.5+δ) films

Single-crystalline perovskite LaBaCo2O5.5+δ thin films were grown on a (110) NdGaO3 single-crystal substrate in order to systematically investigate the effect of lattice mismatch on the electrical transport properties in comparison to the films on LaAlO3, SrTiO3, and MgO substrates. Microstructure studies reveal that all of the LaBaCo2O5.5+δ films are of excellent quality with atomically sharp interface structures. The electrical and magnetic transport property studies indicate that the resistivity, magnetoresistance, and magnetic moment of the film are very sensitive to the substrate materials because of the lattice mismatch/interface strain. The Curie temperature, however, is almost independent of the strain imposed by the substrate, probably because of the strong coupling between the nanodomain boundary and interface strain.

Rise of community-onset urinary tract infection caused by extended-spectrum β-lactamase-producing Escherichia coli in children

BACKGROUND

Urinary tract infection (UTI) caused by resistant bacteria is becoming more prevalent. Few studies are available regarding community-onset UTIs caused by extended-spectrum β-lactamase (ESBL)-producing bacteria in children.

MATERIALS AND METHODS

During a 5-year period, hospitalized children with community-onset UTI caused by ESBL-producing Escherichia coli (case) and those with non-ESBL-producing E. coli (control) were identified. Patients with long-term care facility stay within the preceding month and those with urine cultures obtained >72 hours after admission were excluded. Clinical features and risk factors associated with the occurrence of ESBL-producing E. coli UTI were reviewed.

RESULTS

The prevalence of UTI due to ESBL-producing E. coli increased slightly from 0.59% in 2002 to 0.96% in 2006. A total of 104 cases and 208 controls were included for comparison. The ciprofloxacin resistance of the ESBL-producing E. coli increased significantly in this period (p = 0.006). Pre-existing neurological diseases (p < 0.001), use of antibiotics in the past 3 months (p < 0.001), and recent hospitalization within 1 month (p < 0.001) were found to be potential risk factors. Moreover, previous exposure to third-generation cephalosporins (p < 0.001) and aminoglycosides (p < 0.001) was associated with the selection of ESBL-producing E. coli. Children with ESBL-producing E. coli UTIs had a longer hospital stay (p = 0.031) than those without.

CONCLUSIONS

ESBL-producing E. coli gradually became coresistant to other broad-spectrum antibiotics, notably ciprofloxacin. UTIs caused by such resistant organisms led to a longer hospital stay and more antibiotic use. Reinforcement of infection control measures, especially hand washing in childcare settings and antibiotic stewardship, is critical to reduce the spread of ESBL-producing E. coli.

Dental diagnostic X-ray exposure and risk of benign and malignant brain tumors

BACKGROUND

This study evaluates the risk of benign brain tumors (BBTs) and malignant brain tumors (MBTs) associated with dental diagnostic X-ray, using a large population-based case-control study.

MATERIALS AND METHODS

We identified 4123 BBT cases and 16 492 controls without BBT (study 1) and 197 MBT cases and 788 controls without MBT (study 2) from Taiwan National Health Insurance claim data. The risks of both types of tumor were estimated in association with the frequency of received dental diagnostic X-ray.

RESULTS

The mean ages were ~44.2 years in study 1 and 40.6 years in study 2. Multivariable unconditional logistic regression analysis showed that the risk of BBT increases as the frequency of received dental diagnostic X-ray increases. The BBT odds ratio increased from 1.33 [95% confidence interval (CI) 1.22-1.44] for those with annual mean X-ray examination of less than one to 1.65 (95% CI 1.37-1.98) for those with three or more X-ray examinations, after controlling for comorbidities. No significant association was found between MBTs and dental diagnostic X-ray exposure.

CONCLUSIONS

Exposure to dental diagnostic X-rays in oral and maxillofacial care increases the risk of BBTs, but not MBTs.

Esophageal solid bolus transit: studies using combined multichannel intraluminal impedance and manometry in healthy volunteers

The purpose of this study is to apply combined multichannel intraluminal impedance and esophageal manometry (MII-EM) to test esophageal function during solid swallowing in a normal healthy population. We determined whether combined MII-EM with solid bolus is more sensitive than that with viscous bolus in the detection of motility abnormality. Eighteen healthy volunteers (11 men and 7 women; mean age 22 years, range 20-26 years) underwent combined MII-EM with a catheter containing four impedance-measuring segments and five solid-state pressure transducers. Each subject received 10 viscous and 10 solid materials. Tracings were analyzed manually for bolus presence time, total bolus transit time, contraction amplitude, duration, and onset velocity. Three hundred and sixty swallows including viscous and solid materials were analyzed. Contraction amplitude for the viscous swallows was higher at 20 cm above the lower esophageal sphincter (LES) (P= 0.049) but lower at 15 cm above the LES (P < 0.001). Duration of contractions for the solid swallows was longer at 15 cm (P= 0.002) and 10 cm above the LES (P= 0.011) compared with viscous swallows. The total bolus transit time for solid was significantly shorter than that for viscous boluses (6.8 vs. 7.7 seconds, P < 0.001). Bolus presence time appeared to be similar between viscous and solid boluses (except in the proximal esophagus). The percentage of swallows with ineffective peristalsis by manometry, as well as those with incomplete bolus transit by impedance, did not differ between viscous and solid swallows. The proportion of manometrically ineffective solid swallows with incomplete bolus transit was greater than that of viscous swallows (62.1% vs. 34.8%, P= 0.05). Application of solid boluses may potentially enhance diagnostic capability of esophageal function testing. Solid boluses can be regarded as a valuable complement to viscous boluses in the detection of esophageal motility abnormalities when applied with combined MII-EM.

Linking the DNA strand asymmetry to the spatio-temporal replication program. I. About the role of the replication fork polarity in genome evolution

Two key cellular processes, namely transcription and replication, require the opening of the DNA double helix and act differently on the two DNA strands, generating different mutational patterns (mutational asymmetry) that may result, after long evolutionary time, in different nucleotide compositions on the two DNA strands (compositional asymmetry). We elaborate on the simplest model of neutral substitution rates that takes into account the strand asymmetries generated by the transcription and replication processes. Using perturbation theory, we then solve the time evolution of the DNA composition under strand-asymmetric substitution rates. In our minimal model, the compositional and substitutional asymmetries are predicted to decompose into a transcription- and a replication-associated components. The transcription-associated asymmetry increases in magnitude with transcription rate and changes sign with gene orientation while the replication-associated asymmetry is proportional to the replication fork polarity. These results are confirmed experimentally in the human genome, using substitution rates obtained by aligning the human and chimpanzee genomes using macaca and orangutan as outgroups, and replication fork polarity determined in the HeLa cell line as estimated from the derivative of the mean replication timing. When further investigating the dynamics of compositional skew evolution, we show that it is not at equilibrium yet and that its evolution is an extremely slow process with characteristic time scales of several hundred Myrs.

Wide spread of Tn2006 in an AbaR4-type resistance island among carbapenem-resistant Acinetobacter baumannii clinical isolates in Taiwan

Carbapenem resistance in Acinetobacter baumannii is a global problem. The purpose of this study was to elucidate current resistance mechanisms of imipenem-resistant A. baumannii (IRAB) in Taiwan and their correlation with patient outcomes. Acinetobacter baumannii clinical isolates from two teaching hospitals in Taiwan were collected in 2009 and were examined by Etest for determination of the minimum inhibitory concentrations (MICs) of imipenem, ceftazidime and ceftriaxone. Primers specific for carbapenemase genes and upstream regions were designed for PCR amplification. Bacterial isolates were genotyped by pulsed-field gel electrophoresis (PFGE). Clinical presentations of patients were analysed retrospectively. Upstream insertion sequence ISAba1 was found in 34 isolates that carried bla(OXA-23), including 28 with transposon Tn2006 (ISAba1-bla(OXA-23)-ISAba1) in an AbaR4-type resistance island and 6 with Tn2008 (ISAba1-bla(OXA-23)), as well as in 8 isolates carrying ISAba1-bla(OXA-51-like). All of these isolates expressed full resistance to imipenem (MIC>32 mg/L). Forty-one different PFGE genotypes were found among 62 isolates. Tn2006 was found in 19 genotypes (46.3%), which is more common than ISAba1-bla(OXA-51-like) (12.2%) (P=0.001). Prior use of carbapenems or extended-spectrum cephalosporins for ≥5 days was the only independent risk factor significantly associated with IRAB infection (odds ratio=361.175). Higher mortality was significantly associated with infection caused by IRAB and ISAba1-bla(OXA-23)-carrying strains compared with infection caused by imipenem-susceptible A. baumannii and ISAba1-bla(OXA-51-like)-carrying strains (P=0.009 and 0.027, respectively). Tn2006 is currently the most common imipenem resistance determinant, which showed a higher ability to spread among A. baumannii and was associated with a higher mortality in IRAB-infected patients.

Recognition of mechanisms involved in bile resistance important to halting antimicrobial resistance in nontyphoidal Salmonella

Increasing antimicrobial resistance in nontyphoidal Salmonella (NTS) is a global public health problem that complicates antimicrobial therapy. As an enteric pathogen, Salmonella must endure the presence of bile in the intestinal tract during the course of infection. In this study, we sought to identify Salmonella genes necessary for bile resistance and to investigate their association with antimicrobial resistance. Four genes related to bile resistance were identified, namely rfaP, rfbK, dam and tolC. The first three genes are involved in lipopolysaccharide synthesis, and tolC is associated with an efflux pump. Antimicrobial susceptibility testing showed increased susceptibility to polymyxin B and ciprofloxacin in rfaP and tolC mutants of Salmonella, respectively. Genetic analysis of 45 clinical isolates of NTS revealed that all isolates with reduced susceptibility to fluoroquinolones (minimum inhibitory concentration ≥0.125 mg/L) were associated with point mutations in the quinolone resistance-determining regions of the gyrA and parC genes. The efflux pump also played a role, as evidenced by the reduction in fluoroquinolone resistance when the TolC efflux pump was inhibited by Phe-Arg-β-naphthylamide, a competitive efflux pump inhibitor. Based on these results, we conclude that an intact membrane structure and the efflux pump system provide mechanisms enabling NTS to resist bile. Caution should be taken when using ciprofloxacin and polymyxin B to treat Salmonella enteric infection, as resistance to these agents involves the same mechanisms. Addition of an efflux pump inhibitor to fluoroquinolones may be an effective strategy to deal with the increasing resistance in NTS.

Probable Blastomyces dermatitidis infection in a young rat

A 21-week-old male untreated control SHR/NCrlNarl rat was found dead during an experiment. Grossly, pulmonary lesions were characterized by multifocal to coalescing firm gray-white nodules randomly scattered on the surface. Microscopically, bronchopneumonia was found with pyogranulomas containing neutrophils, macrophages, and numerous thick-walled yeast cells. Yeast cells, 5 to 25 μm in diameter, with no branching of hyphae were observed by staining with hematoxylin and eosin, Diff-Quik, and periodic acid-Schiff. Furthermore, polymerase chain reaction (PCR) using panfungal and nested PCR primers were used for detection of Blastomyces dermatitidis DNA in the lung tissue. After sequencing and matching with DNA sequences in the GenBank, the sample showed a similarity of 94.6% and 97% to Ajellomyces dermatitidis (B. dermatitidis), respectively. On the basis of these results, probable pulmonary blastomycosis was diagnosed. The origin of the infection in the colony rat is undetermined.

The effect of soy isoflavone on bone mineral density in postmenopausal Taiwanese women with bone loss: a 2-year randomized double-blind placebo-controlled study

The treatment of 300-mg/day isoflavones (aglycone equivalents) (172.5 mg genistein + 127.5 mg daidzein) for 2 years failed to prevent lumbar spine and total proximal femur bone mineral density (BMD) from declining as compared with the placebo group in a randomized, double-blind, two-arm designed study enrolling 431 postmenopausal women 45-65 years old.

INTRODUCTION

This study evaluated the effects of soy isoflavones on bone metabolism in postmenopausal women.

METHODS

Four hundred and thirty-one women, aged 45-65 years, orally consumed 300-mg/day isoflavones (aglycone equivalents) or a placebo for 2 years in a parallel group, randomized, double-blind, two-arm study. Each participant also ingested 600 mg of calcium and 125 IU of vitamin D(3) per day. The BMD of the lumbar spine and total proximal femur were measured using dual-energy X-ray absorptiometry at baseline and every half-year thereafter. Serum bone-specific alkaline phosphatase, urinary N-telopeptide of type 1 collagen/creatinine, and other safety assessments were examined regularly.

RESULTS

Two hundred out of 217 subjects in the isoflavone group and 199 out of 214 cases in placebo group completed the treatment. Serum concentrations of isoflavone metabolites, genistein and daidzein, of the intervention group were remarkably elevated following intake of isoflavones (p < 0.001). However, differences in the mean percentage changes of BMD throughout the treatment period were not statistically significant (lumbar spine, p = 0.42; total femur, p = 0.39) between the isoflavone and placebo groups, according to the generalized estimating equation (GEE) method. A significant time trend of bone loss was observed at both sites as assessed by the GEE method following repeated measurement of BMD (p < 0.001). Differences in bone marker levels were not significant between the two treatment groups.

CONCLUSION

Treatment with 300-mg/day isoflavones (aglycone equivalents) failed to prevent a decline in BMD in the lumbar spine or total femur compared with the placebo group.

Hemodynamics of portal venous stenosis before and after treatment in pediatric liver transplantation: evaluation with Doppler ultrasound

AIM

The aim of this study was to evaluate portal vein stenosis (PVS) in pediatric liver transplantation (PLT) using Doppler ultrasound (DUS) before and after interventional management for hemodynamic changes.

MATERIALS AND METHODS

From 2000 to 2010, we encountered 11 PVS cases among 180 PLT that were evaluated using DUS and computed tomography (CT) angiography (CTA); all underwent portal stenting. DUS was used to monitor portal hemodynamics. For the diagnosis of PVS, we investigated multiple parameters including stenotic size (SS), stenotic ratio (SR) (SR [%]=PRE-SS/PRE [PRE=stenotic size]), portal flow velocity ratio (VR) (VR=VS/PRE [PRE=velocity at prestenotic site; VS=peak velocity at stenotic site]), spleen size, and platelet count.

RESULTS

The incidence of PVS was 5.6% (11/180). The PV was 2.5 mm using DUS and 2.7 mm using CTA. The average SR was 65% fitting the criterion. Low prestenotic portal flow<12 cm/sec and high peak velocity in the stenotic segment (up to 147 cm/sec) were observed in 6 cases. The VR value was high at 7.5:1 and there was splenomegaly with thrombocytopenia. After portal vein stenting, hyperperfusion occurred might after reopening the stenosis: the flow increased to an average of 34 cm/sec and then flow decreased slowly to a stable level 2 weeks later. The size of the spleen decreased from 17 to 12 cm and the thrombocytopenia also improved with platelet counts increasing from 67×10(3) to 178×10(3)/μl at 2 months follow-up. The changes in portal flow, portal vein size, spleen size, and platelet count were significant (P<.05).

CONCLUSION

PVS is diagnosed using DUS by increased intrahepatic PV dilatation, peak flow at the stenotic site, discrepant VR. Early portal stenting showed a better prognosis. DUS is essential and effective for hemodynamic monitoring and management of PVS.

Posterior lumbar interbody fusion using spinous process and laminae

Posterior lumbar interbody fusion (PLIF) is indicated for many patients with pain and/or instability of the lumbar spine. We performed 36 PLIF procedures using the patient's lumbar spinous process and laminae, which were inserted as a bone graft between two vertebral bodies without using a cage. The mean lumbar lordosis and mean disc height to vertebral body ratio were restored and preserved after surgery. There were no serious complications. These results suggest that this procedure is safe and effective.

Selenoprotein dSelK in Drosophila elevates release of Ca2+ from endoplasmic reticulum by upregulating expression of inositol 1,4,5-tris-phosphate receptor

dSelK (G-rich), a homolog of human and mouse SelK, is one of three selenoproteins in Drosophila melanogaster. It is the only trans-membrane selenoprotein in D. melanogaster integrated into both the endoplasmic reticulum (ER) membrane and the Golgi apparatus. The gene expression profile of Drosophila Schneider 2 (S2) cells after the dsRNA interference (dsRNAi) targeting of dSelK was examined with the GeneChip Drosophila Genome 2.0 Array (Affymetrix), a high-density oligonucleotide microarray encompassing nearly the full Drosophila genome. The results showed that the transcriptional expression of eight genes whose proteins are located on (or related to) the ER or the Golgi apparatus was highly induced or repressed by the dsRNAi treatment. The mRNA levels of the inositol 1,4,5-tris-phosphate receptor (IP3 receptor), whose gene product is integrated into the ER membrane and regulates the release of Ca2+ from the ER to the cytosol, were significantly downregulated. In contrast, the expression of inositol 1,4,5-tris-phosphate kinase 1, which is a cytosolic protein with opposing functions to the IP3 receptor, was significantly upregulated. Quantitative real-time PCR verified these results. The concentration of intracellular free Ca2+ of the Drosophila S2 cells was significantly decreased after the knockdown of dSelK, whereas overexpression of dSelK significantly increased the intracellular free Ca2+ concentration. These results indicate that dSelK in D. melanogaster is involved in regulating the release of Ca2+ from the ER to the cytosol and may play important roles in the signal transduction pathways involving Ca2+ mobilization.

Increasing ceftriaxone resistance in Salmonellae, Taiwan

In Taiwan, despite a substantial decline of Salmonella enterica serotype Choleraesuis infections, strains resistant to ciprofloxacin and ceftriaxone persist. A self-transferable bla(CMY-2)-harboring IncI1 plasmid was identified in S. enterica serotypes Choleraesuis, Typhimurium, Agona, and Enteritidis and contributed to the overall increase of ceftriaxone resistance in salmonellae.

Increasing ceftriaxone resistance in Salmonellae, Taiwan

In Taiwan, despite a substantial decline of Salmonella enterica serotype Choleraesuis infections, strains resistant to ciprofloxacin and ceftriaxone persist. A self-transferable bla_CMY-2-harboring IncI1 plasmid was identified in S. enterica serotypes Choleraesuis, Typhimurium, Agona, and Enteritidis and contributed to the overall increase of ceftriaxone resistance in salmonellae.

X-Ray spectra and electronic correlations of FeSe(1-x)Te(x)

Critical issues concerning emerging Fe-based superconductors include the degree of electron correlation and the origin of the superconductivity. X-Ray absorption spectra (XAS) and resonant inelastic X-ray scattering spectra (RIXS) of FeSe(1-x)Te(x) (x = 0-1) single crystals were obtained to study their electronic properties that relate to electron correlation and superconductivity. The linewidth of Fe L(2,3)-edges XAS of FeSe(1-x)Te(x) is narrower than that of Fe-pnictides, revealing the difference between their hybridization effects and localization character and those of other Fe-pnictides. While no significant differences exist between the Fe L-edge XAS and RIXS of FeSe(1-x)Te(x) and those of Fe-pnictides, Se K-edge and Te K-edge XAS exhibit substantial edge shift, suggesting that the superconductivity in an Fe-Se superconductor is strongly associated with the ligand states. A comparison of the Se K-edge and Te K-edge spectra reveals that the charge transfer may occur between Se and Te. Given the Coulomb interaction and the bandwidth, the spectral results indicate that FeSe(1-x)Te(x) is unlikely to be a weakly correlated system unlike the Fe-pnictides of the "1111" and "122" families. The spectral results further demonstrate that superconductivity in this class of Fe-based compounds is strongly associated with the ligand 4p hole state.

Effects of mosapride on esophageal secondary peristalsis in humans

BACKGROUND

Secondary peristalsis is important for the clearance of refluxate or retained food bolus from the esophagus. Mosapride is a prokinetic agent that enhances GI motility by stimulating 5-hydroxytrypatamine(4) (5-HT(4) ) receptors, but its effects on secondary peristalsis are yet unclear in humans. We aimed to investigate the effect of a 5-HT(4) agonist mosapride on esophageal distension-induced secondary peristalsis in normal subjects.

METHODS

After a baseline recording esophageal motility, secondary peristalsis was generated by slow and rapid mid-esophageal injections of air in 15 healthy subjects. Two separate sessions with 40mg oral mosapride or placebo were randomly performed to test their effects on esophageal secondary peristalsis.

KEY RESULTS

Mosapride decreased the threshold volume for triggering secondary peristalsis during rapid air distension (4.5±0.3 vs 5.3±0.4mL; P=0.04) but not slow air distension (14.3±1.2 vs 13.3±1.3mL; P=0.41). Secondary peristalsis was triggered more frequently in response to rapid air distension after application of mosapride [100% (90-100%) vs 90% (80-100%); P=0.02]. Mosapride significantly increased pressure wave amplitudes of secondary peristalsis during slow (135.4±13.8 vs 105.0±12.9mmHg; P=0.001) and rapid air distensions (124.0±11.6 vs 95.9±14.0mmHg; P=0.002).

CONCLUSIONS & INFERENCES

Mosapride enhances sensitivity to distension-induced secondary peristalsis and facilitates secondary peristaltic contractility. These data provide an evidence for modulation of esophageal secondary peristalsis by the 5-HT(4) agonist mosapride, as well support for its clinical utility.

Control of esophageal distension-induced secondary peristalsis by the GABA(B) agonist baclofen in humans

BACKGROUND

Secondary peristalsis is important for the clearance of retained food bolus or refluxate from the esophagus. The effects of the gamma aminobutyric acid receptor type B (GABA(B) ) agonist on secondary peristalsis remain unclear in humans. We aimed to investigate the effect of a GABA(B) agonist baclofen on esophageal secondary peristalsis.

METHODS

After a baseline recording of esophageal motility, secondary peristalsis was generated by slow and rapid mid-esophageal injections of air in 15 healthy subjects. Two separate sessions with 40mg oral baclofen or placebo were randomly performed to test their effects on secondary peristalsis.

KEY RESULTS

Baclofen increased the threshold volume for triggering secondary peristalsis during slow air distension (P=0.003) and rapid air distension (P=0.002). Baclofen reduced the rate of secondary peristalsis by rapid air distension from 90% to 30% (P=0.0002). Baclofen increased basal lower esophageal sphincter pressure (P=0.03). Baclofen did not affect any of peristaltic parameters during primary or secondary peristalsis.

CONCLUSIONS & INFERENCES

This study provides an evidence for inhibitory modulation of esophageal secondary peristalsis by the GABA(B) agonist baclofen. Activation of secondary peristalsis is probably modulated by GABA(B) receptors; however, baclofen does not lead to any motility change in secondary peristalsis.

XUTs are a class of Xrn1-sensitive antisense regulatory non-coding RNA in yeast

Non-coding (nc)RNAs are key players in numerous biological processes such as gene regulation, chromatin domain formation and genome stability. Large ncRNAs interact with histone modifiers and are involved in cancer development, X-chromosome inactivation and autosomal gene imprinting. However, despite recent evidence showing that pervasive transcription is more widespread than previously thought, only a few examples mediating gene regulation in eukaryotes have been described. In Saccharomyces cerevisiae, the bona-fide regulatory ncRNAs are destabilized by the Xrn1 5'-3' RNA exonuclease (also known as Kem1), but the genome-wide characterization of the entire regulatory ncRNA family remains elusive. Here, using strand-specific RNA sequencing (RNA-seq), we identify a novel class of 1,658 Xrn1-sensitive unstable transcripts (XUTs) in which 66% are antisense to open reading frames. These transcripts are polyadenylated and RNA polymerase II (RNAPII)-dependent. The majority of XUTs strongly accumulate in lithium-containing media, indicating that they might have a role in adaptive responses to changes in growth conditions. Notably, RNAPII chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) analysis of Xrn1-deficient strains revealed a significant decrease of RNAPII occupancy over 273 genes with antisense XUTs. These genes show an unusual bias for H3K4me3 marks and require the Set1 histone H3 lysine 4 methyl-transferase for silencing. Furthermore, abolishing H3K4me3 triggers the silencing of other genes with antisense XUTs, supporting a model in which H3K4me3 antagonizes antisense ncRNA repressive activity. Our results demonstrate that antisense ncRNA-mediated regulation is a general regulatory pathway for gene expression in S. cerevisiae.

Development of a LytE-based high-density surface display system in Bacillus subtilis

The three N‐terminal, tandemly arranged LysM motifs from a Bacillus subtilis cell wall hydrolase, LytE, formed a cell wall‐binding module. This module, designated CWBM_LytE, was demonstrated to have tight cell wall‐binding capability and could recognize two classes of cell wall binding sites with fivefold difference in affinity. The lower‐affinity sites were approximately three times more abundant. Fusion proteins with β‐lactamase attached to either the N‐ or C‐terminal end of CWBM_LytE showed lower cell wall‐binding affinity. The number of the wall‐bound fusion proteins was less than that of CWBM_LytE. These effects were less dramatic with CWBM_LytE at the N‐terminal end of the fusion. Both CWBM_LytE and β‐lactamase were essentially functional whether they were at the N‐ or C‐terminal end of the fusion. In the optimal case, 1.2 × 10⁷ molecules could be displayed per cell. As cells overproducing CWBM_LytE and its fusions formed filamentous cells (with an average of nine individual cells per filamentous cell), 1.1 × 10⁸β‐lactamase molecules could be displayed per filamentous cell. Overproduced CWBM_LytE and its fusions were distributed on the entire cell surface. Surface exposure and accessibility of these proteins were confirmed by immunofluorescence microscopy.

Imipenem heteroresistance induced by imipenem in multidrug-resistant Acinetobacter baumannii: mechanism and clinical implications

Acinetobacter baumannii has emerged as a major pathogen causing nosocomial infections, particularly in critical patients admitted to the Intensive Care Unit. Increasing resistance to carbapenems in A. baumannii has been observed worldwide. Here we report the clinical impact and mechanism of imipenem heteroresistance (imipenem minimum inhibitory concentration of 6-32 μg/mL with the presence of resistant cells inside the inhibition zone of Etest strips or disks) in multidrug-resistant A. baumannii (MDR-AB). To identify risk factors associated with the emergence of imipenem heteroresistance, a retrospective case-control study was undertaken involving cases with subsequent clinical isolates of the same genotype showing loss of imipenem susceptibility and matched controls with isolates belonging to imipenem-susceptible MDR-AB. The molecular mechanism of heteroresistance was examined. From April 2006 to March 2007, 126 consecutive isolates of MDR-AB were identified from 29 patients. Switch from imipenem susceptibility to heteroresistance was more likely to occur in successive MDR-AB derived from patients who had been exposed to imipenem (length of use 10.9 ± 6.5 days for cases vs. 5.3 ± 4.8 days for controls; P=0.02). An insertion sequence (ISAba1) was found in the promoter region of a class C β-lactamase gene (bla(ADC-29)) in most imipenem-heteroresistant MDR-AB isolates. In vitro experiments indicated that imipenem heteroresistance, which was associated with overexpression of bla(ADC-29), could be induced by imipenem. Carbapenem use was the only risk factor identified for the emergence of carbapenem-heteroresistant MDR-AB. Physicians should weigh the benefits and risks of each carbapenem-based treatment in managing carbapenem-susceptible MDR-AB infection.

Leiomyosarcoma of ovarian vein compression as a cause of hydronephrosis

We present a case of leiomyosarcoma of the right ovarian vein with MRI findings. The patient was a 52-year-old woman who had suffered from right flank pain for one week. Abdominal ultrasound and excretory urography revealed hydronephrosis of the right kidney. Ureteroscopy showed external compression at the right upper third of the ureter. CT and MRI of the abdomen revealed a retroperitoneal mass with compression of the right ureter. The retroperitoneal mass proved on histology to be a leiomyosarcoma arising from the right ovarian vein.

Monitoring and assessing variation of sewage quality and microbial functional groups in a trunk sewer line

In this study, the variation of sewage quality was investigated and the active fraction of different microbial functional groups in biofilm was quantified in a 5.6-km trunk sewer line. The sewage quality including suspended solids, biochemical oxygen demand, total chemical oxygen demand (COD), total nitrogen, total Kjeldahl nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen were measured and compared with the values in literatures. The results indicated that since the wastewater treatment plant was not operated at its full capacity, the concentrations of different compounds were lower compared with the values in literatures. The values of heterotrophic growth rate constant lay between 5.6 and 8.6 day(-1). Its average value was 7.7 day(-1). The values of heterotrophic lysis rate constant lay between 0.2 and 0.4 day(-1). The active heterotrophic biomass in biofilm varied from 240 to 800 mg COD m(-2) and average value was 497 mg COD m(-2). The biofilm mass varied from 880 to 1,080 mg m(-2). The percentage of heterotroph to biofilm mass fall within the range of 24.0-90.9% and average value was 52.9%. In the oxygen uptake rate batch tests, the biomass, growth rate constant, and lysis rate constant of autotroph could not be determined because the fraction of autotroph in biofilm was relatively few. It revealed that the degradation of organic matters, nitrification, and denitrification occurred in the trunk sewer line. But the results indicate that the condition seem favorable for nitrification.

Analysis of pSC138, the multidrug resistance plasmid of Salmonella enterica serotype Choleraesuis SC-B67

Salmonella enterica serotype Choleraesuis (S. Choleraesuis) usually causes systemic infections in man and needs antimicrobial treatment. Multidrug resistance (MDR) in S. Choleraesuis is thus a great concern in the treatment of systemic non-typhoid salmonellosis. A large plasmid, pSC138, was identified in 2002 from a S. Choleraesuis strain SC-B67 that was resistant to all antimicrobial agents commonly used to treat salmonellosis, including ciprofloxacin and ceftriaxone. Complete DNA sequence of the plasmid had been determined previously (Chiu et al., 2005). In the present study, the sequence of pSC138 was reannotated in detail and compared with several newly sequenced plasmids. Some transposable elements and drug resistance genes were further delineated. Plasmid pSC138 was 138,742 bp in length and consisted of 177 open reading frames (ORFs). While 134 of the ORFs displayed significant identity levels to other plasmid and prokaryotic sequences, the remaining 43 ORFs have not been previously reported. Mobile elements, including two integrons, seven insertion sequences and eight transposons, and a truncated prophage together encompass at least 66,781 bp (48.1%) of the plasmid genome. The sequence of pSC138 consists of three major regions: a large composite transposable region Tn6088 with a Tn21-like backbone inserted by a variety of integrons or transposable elements; a transfer/maintenance region that contains a conserved ISEcp1-mediated transposon-like element Tn6092, carrying an AmpC gene, bla(CMY-2), that confers the ceftriaxone resistance; and a Rep_3 type of replication region. Another seven bacteremic strains of S. Choleraesuis that expressed the same MDR phenotype were identified during 2003-2008. The same Rep_3 type replicase and the bla(CMY-2)-containing, ISEcp1-mediated transposon-like element were found in the MDR isolates, suggesting a successful preservation and dissemination of the MDR plasmid. Comparison of pSC138 with other recently published plasmids revealed a high identity level between partial sequences of pSC138 and plasmids of the same or different incompatibility groups. The large MDR region found in pSC138 may provide a niche for the future evolution of the plasmid by acquisition of relevant resistance genes through the panoply of mobile elements and illegitimate recombination events.

Effects of capsaicin-containing red pepper sauce suspension on esophageal secondary peristalsis in humans

BACKGROUND

Capsaicin-sensitive afferents have been implicated in the modulation of gastrointestinal sensorimotor functions. Secondary peristalsis is important for the clearance of retained refluxate or material from the esophagus. The aim of this study was to evaluate the effects of capsaicin-containing red pepper sauce suspension on esophageal secondary peristalsis in healthy adults.

METHODS

After a baseline recording of esophageal motility, secondary peristalsis was generated by slow and rapid mid-esophageal injections of air in 10 healthy subjects. Two separate sessions with saline and capsaicin-containing red pepper sauce were randomly performed to test their effects on esophageal secondary peristalsis.

KEY RESULTS

Infusion of capsaicin significantly increased pressure wave amplitude during rapid (P = 0.002) and slow air infusions (P = 0.01). After capsaicin, the threshold volume to generate secondary peristalsis was significantly decreased during rapid (P < 0.05) and slow air infusions (P = 0.02). Infusion of saline did not affect any parameters of secondary peristalsis during rapid or slow air infusion. The administration of capsaicin was accompanied by the occurrence of heartburn in all subjects.

CONCLUSIONS & INFERENCES

The acute administration of capsaicin-containing red pepper sauce suspension enhances sensitivity to distension-induced secondary peristalsis and facilitates secondary peristaltic contractility. These data suggest the involvement of capsaicin-sensitive afferents in the modulation of esophageal distension-induced secondary peristalsis in humans.

Disease progression in non-erosive reflux disease (NERD): impact of initial esophageal acid exposure

We investigated the 5-year clinical course in a cohort of patients with typical reflux symptoms and negative endoscopy. Prospective follow-up was conducted in patients with non-erosive reflux disease (NERD) for at least 5 years after initial evaluation with esophageal pH monitoring and upper gastrointestinal endoscopy. Within the last year of follow-up, reflux symptoms occurred in 27 of the 30 patients (90%). Twenty-five of twenty-seven symptomatic patients (93%) were on acid suppression therapy. The majority of our patients (70%) remained unchanged regarding their endoscopic status over 5 years. Progression to erosive esophagitis occurred in four patients with Los Angeles (LA) A (13%), three patients with LA B (10%), and two patients with LA C (7%). The presence of pathological acid exposure did not alter the presence of reflux symptoms over 5 years. Disease progression to erosive esophagitis occurred more frequently in patients with pathological acid exposure than those without pathological acid exposure (P= 0.025). Most NERD patients have symptoms and require acid suppression therapy 5 years after their initial diagnosis. Initial pathological acid exposure does not influence the use of acid suppression; however, it does influence the progression of NERD within 5 years of follow-up.

Evidence for neurotrophic factors associating with TRPV1 gene expression in the inflamed human esophagus

BACKGROUND

Transient receptor potential vanilloid-1 (TRPV1) receptor has been implicated in the mechanism of acid induced inflammation in gastro-esophageal reflux disease (GERD). It has been demonstrated that the increase in nerve growth factor (NGF) and glial derived neurotrophic factor (GDNF) was associated with the increased expression of TRPV1. We aimed to determine whether expression of TRPV1 was increased in severe inflamed human esophagus, and to test the hypothesis whether the expression of TRPV1 was mediated by neurotrophic factors such as NGF and GDNF.

METHODS

We compared biopsies taken from the distal esophagus of 15 patients with erosive GERD, 16 asymptomatic patients (AP), and 10 healthy controls. We assessed the biopsies with reverse transcription polymerase chain reaction (RT-PCR) and real-time quantitative polymerase chain reaction (qPCR) for TRPV1, NGF, and GDNF. Immunohistochemical analysis of TRPV1 protein expression was also determined.

KEY RESULTS

Transient receptor potential vanilloid-1 mRNA level and its protein expression were significantly greater in patients with erosive esophagitis than AP (P < 0.001) and healthy controls (P < 0.001). Nerve growth factor and GDNF gene levels in the esophageal mucosa were also significantly increased in patients with erosive esophagitis compared with AP and healthy controls (all P < 0.001). Transient receptor potential vanilloid-1 mRNA correlated well with NGF (r = 0.61, P < 0.001) and GDNF (r = 0.58, P < 0.001).

CONCLUSIONS & INFERENCES

These results support the association of NGF and GDNF in the up-regulation of TRPV1 receptors in patients with erosive esophagitis.

Ferroelectric BaTiO3 thin films on Ti substrate fabricated using pulsed-laser deposition

We report on the fabrication of ferroelectric BaTiO3 thin films on titanium substrates using pulsed laser deposition and their microstructures and properties. Electron microscopy studies reveal that BaTiO3 films are composed of crystalline assemblage of nanopillars with average cross sections from 100 nm to 200 nm. The BaTiO3 films have good interface structures and strong adhesion with respect to Ti substrates by forming a rutile TiO2 intermediate layer with a gradient microstructure. The room temperature ferroelectric polarization measurements show that the as-deposited BTO films possess nearly the same spontaneous polarization as the bulk BTO ceramics indicating formation of ferroelectric domains in the films. Successful fabrication of such ferroelectric films on Ti has significant importance for the development of new applications such as structural health monitoring spanning from aerospace to civil infrastructure. The work can be extended to integrate other ferroelectric oxide films with various promising properties to monitor the structural health of materials.

Two-dimensional metallic tungsten nanowire network fabricated by electron-beam-induced deposition

One-dimensional tungsten nanowires and two-dimensional tungsten nanowire networks were fabricated on a tungsten substrate by using electron-beam-induced deposition (EBID) without precursor injection. The as-prepared tungsten nanostructures were studied using a combination of energy-dispersive x-ray spectroscopy and selected area electron diffraction. It was revealed that the tungsten nanostructures were composed of pure metallic tungsten. The WO(3) oxide formed in the chemical preparation of tungsten foils was probably the source of tungsten for the fabrication of tungsten nanostructures by EBID.

Application of low-volume zero-balanced ultrafiltration and its effect on blood propofol concentration: a randomized controlled trial

AIM

The aim of this study was to evaluate the effectiveness of low-volume zero-balanced ultrafiltration during cardiopulmonary bypass in heart valve replacement surgery.

METHODS

This was a randomized, double-blind, controlled study carried out in the operating room. Forty patients of ASA grade II-III, elected to undergo heart valve replacement surgery, were enrolled. All patients were randomly assigned to either a low-volume (35 mL/kg) zero-balanced ultrafiltration group (N.=20) or to a control group (N.=20). Blood propofol concentrations and entropy index were measured using cardiopulmonary bypass. Concentrations of plasma tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-10 (IL-10), and cardiac troponin I were measured before and after the end of cardiopulmonary bypass and corrected according to hematocrit.

RESULTS

Blood levels of cardiac troponin I, TNF-alpha, IL-6, and IL-10 after surgery were all significantly lower in the ultrafiltration group than in the control group (P<0.05) after the end of bypass. Blood propofol concentrations decreased significantly in both groups during cardiopulmonary bypass and remained significantly lower in the ultrafiltration group than the control group. However, there was no significant difference between the two groups in the entropy index (P=0.5583).

CONCLUSION

Low-volume zero-balanced ultrafiltration performed during cardiopulmonary bypass surgery significantly decreased post-bypass levels of the cytokines, TNF-alpha, IL-6, IL-10, and postoperative cardiac troponin I. Blood propofol concentration was also decreased; however, the depth of anesthesia was not affected significantly.

Clonal dissemination of the multi-drug resistant Salmonella enterica serovar Braenderup, but not the serovar Bareilly, of prevalent serogroup C1 Salmonella from Taiwan

Background

Nontyphoidal Salmonella is the main cause of human salmonellosis. In order to study the prevalent serogroups and serovars of clinical isolates in Taiwan, 8931 Salmonellae isolates were collected from 19 medical centers and district hospitals throughout the country from 2004 to 2007. The pulsed-field eletrophoresis types (PFGE) and antibiotic resistance profiles of Salmonella enterica serovars Bareilly (S. Bareilly) and Braenderup (S. Braenderup) were compared, and multi-drug resistance (MDR) plasmids were characterized.

Results

Over 95% of human salmonellosis in Taiwan was caused by five Salmonella serogroups: B, C1, C2-C3, D1, and E1. S. Typhymurium, S. Enteritidis, S. Stanley and S. Newport were the four most prevalent serovars, accounting for about 64% of isolates. While only one or two major serovars from four of the most prevalent serogroups were represented, four predominant serovars were found in serogroup C1 Salmonellae. The prevalence was decreasing for S. Choleraeuis and S. Braenderup, and S. Virchow and increasing for S. Bareilly. S. Braenderup mainly caused gastroenteritis in children; in contrast, S. Bareiley infected children and elderly people. Both serovars differed by XbaI-PFGE patterns. Almost all S. Bareilly isolates were susceptible to antibiotics of interest, while all lacked plasmids and belonged to one clone. Two distinct major clones in S. Braenderup were cluster A, mainly including MDR isolates with large MDR plasmid from North Taiwan, and cluster B, mainly containing susceptible isolates without R plasmid from South Taiwan. In cluster A, there were two types of conjugative R plasmids with sizes ranging from 75 to 130 kb. Type 1 plasmids consisted of replicons F1A/F1B, bla_TEM, IS26, and a class 1 integron with the genes dfrA12-orfF-aadA2-qacEΔ1-sulI. Type 2 plasmids belonged to incompatibility group IncI, contained tnpA-bla_CMY-2-blc-sugE genetic structures and lacked both IS26 and class 1 integrons. Although type 2 plasmids showed higher conjugation capability, type 1 plasmids were the predominant plasmid.

Conclusions

Serogroups B, C1, C2-C3, D1, and E1 of Salmonella caused over 95% of human salmonellosis. Two prevalent serovars within serogroup C1, S. Bareilly and cluster B of S. Braenderup, were clonal and drug-susceptible. However, cluster A of S. Braenderup was MDR and probably derived from susceptible isolates by acquiring one of two distinct conjugative R plasmids.

Evidence for oesophageal visceral hypersensitivity and aberrant symptom referral in patients with globus

We tested the hypotheses that globus patients demonstrate oesophageal visceral hypersensitivity and aberrant viscerosomatic referral of oesophageal stimuli. Oesophageal visceral perception was assessed by oesophageal balloon distension and electrical stimulation in nine patients with globus and compared with 11 healthy controls. Oesophageal perception and pain thresholds were determined. Subjects recorded the area of thoracic viscerosomatic referral on a body map in response to each stimulus. All the patients reported their first sensation at balloon volumes between 2 and 6 mL whereas controls reported their first sensation at volumes between 3 and 14 mL (P = 0.03). All the patients reported pain at balloon volumes between 5 and 12 mL whereas controls experienced pain at volumes between 8 and 20 mL (P = 0.001). In response to electrical stimulation to the oesophagus patients and controls demonstrated comparable sensory thresholds. In response to oesophageal balloon distension seven of nine patients, but no controls, referred the sensation to the region at or above the suprasternal notch (P = 0.001). Similarly, significant differences in viscerosomatic referral pattern were observed in response to oesophageal electrical stimulation (P = 0.03). Patients with globus demonstrate oesophageal visceral hypersensitivity to mechanical distension. The differential responses to stretch and electrical stimuli may indicate that the hypersensitivity is a peripheral, rather than central, phenomenon. The aberrant referral of oesophageal sensations in response to both mechanical and electrical stimulation supports the hypothesis that referral of symptoms to the neck might be a central phenomenon.