bluuebunny/crossref_metadata_2025 huggingface dataset:
Longitudinal Trends in Antimicrobial Susceptibilities Across Long-Term–Care Facilities: Emergence of Fluoroquinolone Resistance
Authors: Viray Melissa , Linkin Darren , Maslow Joel N. , Stieritz Donald D. , Carson Lesley S. , Bilker Warren B. , Lautenbach Ebbing
Published: April 2006

Background

Antibiotic resistance in the long-term-care facility (LTCF) setting is of increasing concern due to both the increased morbidity and mortality related to infections in this debilitated population and the potential for transfer of resistant organisms to other healthcare settings. Longitudinal trends in antibiotic resistance in LTCFs have not been well described.

Design:

Correlational longitudinal survey study.

Setting:

Four LTCFs in Pennsylvania.

Subjects:

All clinical cultures of residents of the participating LTCFs (700 total beds) from 1998 through 2003. We assessed the annual prevalence of resistance to various antimicrobials of interest for the following organisms: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and enterococcus species.

Results:

A total of 4,954 clinical isolates were obtained during the study. A high prevalence of antimicrobial resistance was noted for many organism-drug combinations. This was especially true for fluoroquinolone susceptibility among the Enterobacteriaceae (susceptibility range, 51.3% to 92.2%). In addition, the prevalence of resistance to various agents differed significantly across study sites. Finally, significant increasing trends in resistance were noted over time and were most pronounced for fluoroquinolone susceptibility among the Enterobacteriaceae.

Conclusions:

The prevalence of antimicrobial resistance has increased significantly in LTCFs, although trends have varied substantially across different institutions. These trends have been particularly pronounced for fluoroquinolone resistance among the Enterobacteriaceae. These findings demonstrate that antimicrobial resistance is widespread and increasing in LTCFs, highlighting the need for future studies to more clearly elucidate the risk factors for, and potential interventions against, emerging resistance in these settings.
Spread of Clones of Multidrug-Resistant, Coagulase-Negative Staphylococci Within a University Hospital
Authors: Monsen Tor , Karlsson Carina , Wiström Johan
Published: April 2006

Objective:

To detect putative clonal dissemination of multidrug-resistant, coagulase-negative staphylococci (CNS) in a university hospital in northern Sweden.

Methods:

All consecutive routine clinical samples from our hospital were screened during two periods (November and December 2001 and September and October 2002) for the presence of multidrug-resistant (defined as resistant to oxacillin, clindamycin, co-trimoxazole, gentamicin, and fusidic acid, but susceptible to vancomycin) isolates of CNS. Genetic similarity between isolates was analyzed using pulsed-field gel electrophoresis (PFGE) and a computer program.

Results:

Seventy multidrug-resistant isolates from 62 patients were identified, 28 during the 2001 period and 42 during the 2002 period. All isolates except one, which wasStaphylococcus haemolyticus, were identified asS. epidermidis. Multidrug-resistant CNS were isolated in samples obtained from 24 different wards. Two subgroups (group A and group B) ofS. epidermidisthat differed by approximately 40% in PFGE band similarity were identified. Group A consisted of 44 isolates with a PFGE band similarity of greater than 70% that included 6 subgroups consisting of 3 to 16 isolates that expressed a 100% similarity. These isolates were identified during both sampling periods in cultures performed in 18 different wards. A clonal origin could not be excluded for some of the remaining 26 isolates belonging to group B, but none had identical PFGE patterns, suggesting a more diverse origin.

Conclusion:

The results of this study suggest clonal spread of multidrug-resistant CNS within our hospital and that some clones are endemic in the hospital environment.
High Rate of Coadministration of Di- or Tri-valent Cation-Containing Compounds With Oral Fluoroquinolones: Risk Factors and Potential Implications
Authors: Barton Todd D. , Fishman Neil O. , Weiner Mark G. , LaRosa Lori A. , Lautenbach Ebbing
Published: April 2006

Background:

The characteristics of fluoroquinolone use that increase the risk of selecting for fluoroquinolone resistance remain unclear. Exposure to subtherapeutic levels of fluoroquinolone promotes bacterial development of fluoroquinolone resistance. Oral fluoroquinolone absorption is significantly impaired by coadministration with many common di- or tri-valent cation-containing compounds (DTCCs), and this interaction has been associated with therapeutic failure. However, the prevalence of, and risk factors for, in-hospital coadministration of oral fluoroquinolones with DTCCs is unknown.

Design:

Case-control study.

Setting:

A 625-bed, tertiary-care medical center.

Patients:

All inpatients who were dispensed oral levofloxacin from July 1, 1999, to June 30, 2001, were included. Coadministration was defined by documented administration of any DTCC within 2 hours of levofloxacin. Complete coadministration was defined as coadministration complicating every dose of a course of levofloxacin.

Results:

A subset of 3,227 (41.0%) of 7,871 doses of levofloxacin that occurred during the same calendar day as any DTCC was selected for further review. Overall, 1,904 (77.1%) of 2,470 doses of oral levofloxacin reviewed were complicated by coadministration with at least one DTCC. On multivariable analysis, an increased number of prescribed medications was significantly associated with complete coadministration (per increase of one medication: OR, 1.05; CI95, 1.01–1.10;P= .036), whereas patient location in an ICU was protective (OR, 0.51; CI95, 0.30–0.87;P= .013). If our prevalence results are extrapolated to all patients receiving oral levofloxacin at our hospital, approximately one in three doses was complicated by coadministration.

Conclusion:

Coadministration of fluoroquinolones with DTCCs is extremely common and significantly associated with polypharmacy.
High Prevalence of Carriage of Methicillin-ResistantStaphylococcus aureusat Hospital Admission in Elderly Patients: Implications for Infection Control Strategies
Authors: Lucet Jean-Christophe , Grenet Karine , Armand-Lefevre Laurence , Harnal Marion , Bouvet Elisabeth , Regnier Bernard , Andremont Antoine
Published: April 2006

Background:

Despite contact isolation precautions for patients with methicillin-resistantStaphylococcus aureus(MRSA), MRSA infections are increasing in many countries.

Objective:

To evaluate the role of a potential unrecognized reservoir of MRSA carried by patients in acute care wards, we determined the prevalence of MRSA at hospital admission, with special emphasis on screening-specimen yields.

Setting:

A 1,100-bed teaching hospital in Paris, France.

Methods:

Nasal screening cultures were performed at admission to a tertiary-care teaching hospital for patients older than 75 years.

Results:

MRSA was isolated from 63 (7.9%) of 797 patients. On the multivariate analysis, variables significantly associated with MRSA carriage were presence of chronic skin lesions (adjusted odds ratio [AOR], 5.10; 95% confidence interval [CI95], 2.52–10.33); transfer from a nursing home, rehabilitation unit, or long-term-care unit (AOR, 4.52; CI95, 2.23–9.18); and poor chronic health status (AOR, 1.80; CI95, 1.02–3.18). Without admission screening, 84.1% of MRSA carriers would have been missed at hospital admission and 76.2% during their hospital stay. Furthermore, 81.1% of days at risk for MRSA dissemination would have been spent without contact isolation precautions had admission screening not been performed.

Conclusions:

MRSA carriage at hospital admission is far more prevalent than MRSA-positive clinical specimens. This may contribute to failure of contact isolation programs. Screening cultures at admission help to identify the reservoir of unknown MRSA patients.
Molecular Surveillance of Clinical Methicillin-ResistantStaphylococcus aureusIsolates in Neonatal Intensive Care Units
Authors: Huang Yhu-Chering , Su Lin-Hui , Wu Tsu-Lan , Lin Tzuo-Yien
Published: April 2006

Background and Objective:

Methicillin-resistantStaphylococcus aureus(MRSA) has become an important nosocomial pathogen in our neonatal intensive care units (NICUs) and accounts for almost allS. aureusclinical isolates. The objective of this study was to assess the relatedness of these MRSA strains.

Design:

MRSA clinical isolates were collected from infants hospitalized in our NICUs. Pulsed-field gel electrophoresis withSmaI digestion was used to fingerprint these isolates.

Setting:

Level-III NICUs in a university-affiliated children's hospital.

Results:

Between 1998 and 2000, a total of 122 MRSA clinical isolates were collected from 104 infants hospitalized in our NICUs. Fifteen infants had multiple isolates (range, 2 to 4 isolates). The sources of specimens included blood (72), pus (23), sputum (15), body fluids (3), and catheter tips (9). A total of 4 genotypes with 20 subtypes were identified. There were 2 genotypes in 1998, 2 genotypes in 1999, and 4 genotypes in 2000. All but 2 isolates belonged to either genotype A (63.1%; 7 subtypes) or genotype C (35.2%; 11 subtypes). Among the 15 infants with multiple isolates, the genotypes of the isolates from a single episode of MRSA infection were different in 2 of 12 cases, and reinfection with a new strain was noted in 3 of 5 cases with recurrent infections.

Conclusions:

Two predominant MRSA clones prevailed in our NICUs between 1998 and 2000. Polyclonal bacteremia and reinfection with a new strain were noted.
Risk Factors for Colonization With Methicillin-ResistantStaphylococcus aureusin a Long-Term-Care Facility in Slovenia
Authors: Vovko Petra , Retelj Matjaz , Cretnik Tjasa Zohar , Jutersek Borut , Harlander Tatjana , Kolman Jana , Gubina Marija
Published: April 2006

Objective:

To evaluate risk factors associated with methicillin-resistantStaphylococcus aureus(MRSA) colonization in a long-term-care facility (LTCF) for the elderly in Slovenia.

Setting:

A 351-bed community LTCF for the elderly.

Design and Participants:

This was a case-control study. MRSA carriage was identified in 102 of 127 residents of the facility's nursing unit. Two swabs were taken: one from the anterior nares and one from the largest skin lesion. If no skin lesions were present, the axillae and the groin area were swabbed. Data were collected regarding gender, age, length of stay in the facility, underlying conditions, functional status, presence of wounds or pressure sores, presence of catheters, antibiotic treatments, and hospital admissions.

Results:

We detected MRSA in 12 participants. Risk factors independently and significantly associated with MRSA colonization on the multivariate analysis were antibiotic treatments within 1 month before the investigation (odds ratio, 5.087; 95% confidence interval, 1.02 to 25.48;P= .048) and multiple hospital admissions in the 3 months before the investigation (odds ratio, 6.277; 95% confidence interval, 1.31 to 30.05;P= .022).

Conclusions:

This is the first assessment of risk factors for colonization with MRSA in an LTCF in Slovenia. MRSA poses a problem in this LTCF. Our observations may be valuable in implementing active surveillance cultures in infection control programs in Slovenian LTCFs.
Standardized Infection Surveillance in Long-Term Care Interfacility Comparisons From a Regional Cohort of Facilities
Authors: Stevenson Kurt B. , Moore James , Colwell Holly , Sleeper Barbara
Published: April 2006

Objectives:

To measure infection rates in a regional cohort of long-term-care facilities (LTCFs) using standard surveillance methods and to analyze different methods for interfacility comparisons.

Setting:

Seventeen LTCFs in Idaho.

Design:

Prospective, active surveillance for LTCF-acquired infections using standard definitions and case-finding methods was conducted from July 2001 to June 2002. All surveillance data were combined and individual facility performance was compared with the aggregate employing a variety of statistical and graphic methods.

Results:

The surveillance data set consisted of 472,019 resident-days of care with 1,717 total infections for a pooled mean rate of 3.64 infections per 1,000 resident-days. Specific infections included respiratory (828; rate, 1.75), skin and soft tissue (520; rate, 1.10), urinary tract (282; rate, 0.60), gastrointestinal (77; rate, 0.16), unexplained febrile illnesses (6; rate, 0.01), and bloodstream (4; rate, 0.01). Initially, methods adopted from the National Nosocomial Infections Surveillance System were used comparing individual rates with pooled means and percentiles of distribution. A more sensitive method appeared to be detecting statistically significant deviations (based on chi-square analysis) of the individual facility rates from the aggregate of all other facilities. One promising method employed statistical process control charts (U charts) adjusted to compare individual rates with aggregate monthly rates, providing simultaneous visual and statistical comparisons. Small multiples graphs were useful in providing images valid for rapid concurrent comparison of all facilities.

Conclusion:

Interfacility comparisons have been demonstrated to be valuable for hospital infection control programs, but have not been studied extensively in LTCFs.
Failure to Control an Outbreak of Multidrug-ResistantStreptococcus pneumoniaein a Long-Term–Care Facility Emergence and Ongoing Transmission of a Fluoroquinolone-Resistant Strain
Authors: Carter Rosalind J. , Sorenson Genevieve , Heffernan Richard , Kiehlbauch Julia A. , Kornblum John S. , Leggiadro Robert J. , Nixon Lucia J. , Wertheim William A. , Whitney Cynthia G. , Layton Marcelle ,   MDRSP Working Group
Published: April 2006

Objectives:

To characterize risk factors associated with pneumococcal disease and asymptomatic colonization during an outbreak of multidrug-resistantStreptococcus pneumoniae(MDRSP) among AIDS patients in a long-term–care facility (LTCF), evaluate the efficacy of antimicrobial prophylaxis in eliminating MDRSP colonization, and describe the emergence of fluoroquinolone resistance in the MDRSP outbreak strain.

Design:

Epidemiologic investigation based on chart review and characterization of SP strains by antimicrobial susceptibility testing and PFGE and prospective MDRSP surveillance.

Setting:

An 80-bed AIDS-care unit in an LTCF.

Participants:

Staff and residents on the unit.

Results:

From April 1995 through January 1996, 7 cases of MDRSP occurred. A nasopharyngeal (NP) swab survey of all residents (n = 65) and staff (n = 70) detected asymptomatic colonization among 6 residents (9%), but no staff. Isolates were sensitive only to rifampin, ofloxacin, and vancomycin. A 7-day course of rifampin and ofloxacin was given to eliminate colonization among residents: NP swab surveys at 1, 4, and 10 weeks after prophylaxis identified 1 or more colonized residents at each follow-up with isolates showing resistance to one or both treatment drugs. Between 1996 and 1999, an additional 6 patients were diagnosed with fluoroquinolone-resistant (FQ-R) MDRSP infection, with PFGE results demonstrating that the outbreak strain had persisted 3 years after the initial outbreak was recognized.

Conclusions:

Chemoprophylaxis likely contributed to the development of a FQ-R outbreak strain that continued to be transmitted in the facility through 1999. Long-term control of future MDRSP outbreaks should rely primarily on vaccination and strict infection control measures.
An Outbreak of Norovirus Infection in a Long-Term-Care Unit in Spain
Authors: Navarro Gemma , Sala Rosa M. , Segura Ferran , Arias César , Varela Pilar , Peña Pilar , Llovet Teresa , Sanfeliu Isabel , Canals Maria , Serrate Guadalupe , Nogueras Antonio
Published: April 2006

Background:

Norovirus belongs to the Caliciviridae family and causes outbreaks of infectious enteritis by fecal-oral transmission. In Spain, there have been few outbreaks reported due to this virus. We describe an outbreak on a long-term-care hospital ward.

Methods:

Cases were classified as probable, confirmed, and secondary. Stool cultures were performed. Polymerase chain reaction detection of norovirus was also performed.

Results:

The outbreak occurred from December 7 to 28, 2001, involving 60 cases (32 patients, 19 staff members, 8 patients' relatives, and 1 relative of a staff member). Most (82%) of the cases were female. The most frequently involved ages were 20 to 39 years for staff members and 70 to 89 years for patients. The incubation period of secondary cases in patients' families had a median of 48 hours (range, 1 to 7 days). Clinical symptoms included diarrhea (85%), vomiting (75%), fever (37%), nausea (23%), and abdominal pain (12%). Median duration of the disease was 48 hours (range, 1 to 7 days). All cases resolved and the outbreak halted with additional hygienic measures. Stool cultures were all negative for enteropathogenic bacteria and rotaviruses. In 16 of 23 cases, the norovirus genotype 2 antigen was detected.

Conclusion:

This outbreak of gastroenteritis due to norovirus genotype 2 affected patients, staff members, and their relatives in a long-term-care facility and was controlled in 21 days.
Health and Economic Consequences of an Outbreak of Pertussis Among Healthcare Workers in a Hospital in France
Authors: Ward Alexandra , Caro Jaime , Bassinet Laurence , Housset Bruno , O'Brien Judith A. , Guiso Nicole
Published: April 2006

Background:

Bordetella pertussisis highly contagious, and because immunity wanes after vaccination, it continues to be a cause of cough among adults.

Objective:

To describe the healthcare services used and productivity losses accrued by healthcare workers (HCWs) missing work due to pertussis.

Methods:

After 3 pertussis cases were confirmed among HCWs, all hospital employees and patients with a cough were screened between November 2000 and March 2001. Each potential case underwent diagnostic tests and received antibiotics (spiramycin or azithromycin) when appropriate. Symptomatic employees were not allowed to return to work until they received an antibiotic for at least 5 days. Services used (physician visits and calls, antibiotics, diagnostic tests, hospitalization, and treatment provided to their contacts) were combined with cost estimates (in 2002 euros) for these services in France.

Results:

Ninety-one potential cases were identified (77 HCWs, 12 patients, and 2 family members). Of them, 89% received antibiotics and 22% had at least one contact who was also treated. Approximately half (55%) of the HCWs who were cases missed 5 days of work. Four patients were admitted to the hospital as a result of the infection. The average medical cost was 297 euros per potential case: diagnostic tests accounted for 32% and hospitalization for 31%. Total cost (medical and productivity) was 46,661 euros for 91 cases, 42% from productivity losses. An investigation to identify these potential cases also accrued additional costs.

Conclusion:

Serious adverse health and economic consequences arose from transmission of pertussis among HCWs, their families, and patients.
Attitudes and Perceptions Toward Hand Hygiene Among Healthcare Workers Caring for Critically Ill Neonates
Authors: Pessoa-Silva Carmem Lucia , Posfay-Barbe Klara , Pfister Riccardo , Touveneau Sylvie , Perneger Thomas V. , Pittet Didier
Published: April 2006

Background:

Infectious complications are frequent among critically ill neonates. Hand hygiene is the leading measure to prevent healthcare-associated infections, but poor compliance has been repeatedly documented, including in the neonatal setting. Hand hygiene promotion requires a complex approach that should consider personal factors affecting healthcare workers' attitudes.

Objective:

To identify beliefs and perceptions associated with intention to comply with hand hygiene among neonatal healthcare workers.

Methods:

An anonymous, self-administered questionnaire (74 items) based on the theory of planned behavior was distributed to 80 neonatal healthcare workers to assess intention to comply, attitude toward hand hygiene, behavioral and subjective norm perceptions, and perception of difficulty to comply. Variables were assessed using multi-item measures and answers to 7-point bipolar scales. All multi-item scales had satisfactory internal consistency (alpha > 0.7). Multivariate logistic regression identified independent perceptions or beliefs associated with a positive intention to comply.

Results:

The response rate was 76% (61 of 80). Of the 49 nurses and 12 physicians responding, 75% believed that they could improve their compliance with hand hygiene. Intention to comply was associated with perceived control over the difficulty to perform hand hygiene (OR, 3.12; CI95, 1.12 to 8.70; P = .030) and a positive perception of how superiors valued hand hygiene (OR, 2.89; CI95, 1.08 to 7.77; P = .035).

Conclusion:

Our data highlight the importance of the opinions of superiors and a strong perceived controllability over the difficulty to perform hand hygiene as possible internal factors that may influence hand hygiene compliance.
Efficiency of Hand Drying for Removing Bacteria From Washed Hands Comparison of Paper Towel Drying With Warm Air Drying
Authors: Yamamoto Yukiko , Ugai Kazuhiro , Takahashi Yasuko
Published: April 2006

Objective:

To evaluate warm air and paper towel drying for removing bacteria from washed hands.

Methods:

After hands were washed with non-antibacterial soap, they were dried using warm air with and without ultraviolet light, while being rubbed or held stationary, or paper towels. Each method was performed as a randomized trial using 30 hands.

Results:

Log colony-forming units (CFU) on palms and fingers increased significantly when hands were dried with warm air while being rubbed for 15 seconds (P< .001), and many bacteria remained at 30 seconds without ultraviolet light (P< .001). Holding hands stationary while drying significantly decreased log CFU on palms, fingers, and fingertips (P< .01 or < .001). Few CFU were detected on palms and fingers dried with ultraviolet light. Although log CFU of palms and fingers did not decrease after drying with three sheets of paper towel, those of fingertips decreased significantly (P< .001). For palms and fingers, log reductions were greater with warm air drying while holding hands stationary, paper towels, and warm air drying while rubbing hands. For fingertips, the log reduction was often greater with paper towels than with warm air.

Conclusions:

Holding hands stationary and not rubbing them was desirable for removing bacteria. Ultraviolet light reinforced the removal of bacteria during warm air drying. Paper towels were useful for removing bacteria from fingertips but not palms and fingers.
Behavior of Cross-Sectional Surveys in the Hospital Setting: A Simulation Model
Authors: Rossello-Urgell Jose , Rodriguez-Pla Alicia
Published: April 2006

Objective:

To date, it has not been adequately proven whether the published formulas used to obtain incidence from the prevalence of nosocomial infections provide a good estimate of real incidence. With the hypothesis that within the hospital setting prevalence may be lower than incidence, the aim of this study was to analyze the behavior of point prevalence as it relates to cumulative incidence and duration of infection.

Design:

Hospital simulation study.

Methods:

By randomly selecting a sample of infected patients within a specific range of cumulative incidences and infection durations, we constructed a simulated hospital population, allowing us to estimate daily point prevalences and their maximum and minimum values. The association between the different components of stay and cumulative incidence was evaluated to obtain a more accurate estimate of incidence.

Results:

Prevalence can be lower than, equal to, or higher than the corresponding incidence. For all incidence levels, prevalence was increasing with duration. Between 14 and 20 days of infection duration, prevalence was consistently lower than incidence. Prevalence duration of infection was approximately half the time of the total duration.

Conclusions:

The existing formulas relating incidence and prevalence can frequently be inadequate. Until a validated system for converting prevalence into incidence is available, we do not believe their use is appropriate.
Antimicrobial Consumption Data From Pharmacy and Nursing Records: How Good Are They?
Authors: Itokazu Gail S. , Glowacki Robert C. , Schwartz David N. , Wisniewski Mary F. , Rydman Robert J. , Weinstein Robert A.
Published: April 2006

Objective:

To determine whether randomly selected intravenous (IV) antimicrobial doses dispensed from an inpatient pharmacy were administered.

Design:

This was a prospective, cross-sectional study in which dose administration was confirmed by direct observation and by assessment of the medication administration record (MAR). A retrospective analysis of the return rate of unused IV antimicrobial doses was performed subsequently.

Setting:

Medical and surgical intensive care units (ICUs) and non-ICUs of a 550-bed urban public teaching hospital.

Participants:

Hospitalized patients with an order in the pharmacy database for an IV antimicrobial during 9 non-consecutive weekdays in June 1999.

Results:

Of 397 doses, 221 (55.7%) assessed by bedside observation and 238 (59.9%) assessed by MAR review were classified as administered; 139 doses (35.0%) were dispensed but changes in the drug order or the patient's status prevented their administration. In the subsequent assessment, of 745 IV antimicrobial doses dispensed during 24 hours, 322 (43.2%) were returned to the pharmacy unused; 423 (56.8%) of the doses—consistent with our prior observations—were presumably administered.

Conclusions:

Because computerized pharmacy data may overestimate actual antimicrobial consumption, such data should be validated when used in studies of hospital antimicrobial use. Dispense-return analysis offers a simple validation method.
A Comparative Study of Ethylene Oxide Gas, Hydrogen Peroxide Gas Plasma, and Low-Temperature Steam Formaldehyde Sterilization
Authors: Kanemitsu Keiji , Imasaka Takayuki , Ishikawa Shiho , Kunishima Hiroyuki , Harigae Hideo , Ueno Kumi , Takemura Hiromu , Hirayama Yoshihiro , Kaku Mitsuo
Published: April 2006

Objective:

To compare the efficacies of ethylene oxide gas (EOG), hydrogen peroxide gas plasma (PLASMA), and low-temperature steam formaldehyde (LTSF) sterilization methods.

Methods:

The efficacies of EOG, PLASMA, and LTSF sterilization were tested using metal and plastic plates, common medical instruments, and three process challenge devices with narrow lumens. All items were contaminated with Bacillus stearothermophilus spores or used a standard biological indicator.

Results:

EOG and LTSF demonstrated effective killing of B. stearothermophilus spores, with or without serum, on plates, on instruments, and in process challenge devices. PLASMA failed to adequately sterilize materials on multiple trials in several experiments, including two of three plates, two of three instruments, and all process challenge devices.

Conclusions:

Our results suggest that PLASMA sterilization may be unsuccessful under certain conditions, particularly when used for items with complex shapes and narrow lumens. Alternatively, LTSF sterilization demonstrates excellent efficacy and is comparable to EOG sterilization. LTSF could potentially act as a substitute if EOG becomes unavailable due to environmental concerns.
A Randomized, Controlled Trial of a New Vascular Catheter Flush Solution (Minocycline-EDTA) in Temporary Hemodialysis Access
Authors: Bleyer Anthony J. , Mason Lori , Russell Gregory , Raad Issam I. , Sherertz Robert J.
Published: April 2006

Background and Objective:

We previously demonstrated that minocycline-EDTA was efficacious at preventing catheter-related bloodstream infections (BSIs) in three patients with recurrent infections. This study compared heparin with minocycline-EDTA as flush solutions used among dialysis patients with central venous catheters, a high-risk group for catheter-related BSI.

Methods:

Patients were enrolled within 72 hours of catheter insertion and randomized to receive heparin or minocycline-EDTA as a flush after each dialysis session. Each syringe containing flush solution was wrapped in orange plastic to conceal the type of solution it contained. Patients were observed for evidence of infection and catheter thrombosis. After catheters were removed, cultures were performed to determine whether microbial colonization had occurred.

Results:

During a 14-month period, 60 patients were enrolled (30 in each group). The two groups had similar demographics and underlying diseases. Catheter survival at 90 days was 83% for the minocycline-EDTA group versus 66% for the heparin group (P= .07). Significant catheter colonization, a surrogate measure of catheter-related infection, was significantly more frequent in the heparin group (9 of 14 vs 1 of 11;P= .005). There was only one catheter-related bacteremia and it occurred in the heparin group.

Conclusions:

When compared with heparin, minocycline-EDTA had a better 90-day catheter survival (P= .07) and a decreased rate of catheter colonization. This pilot study warrants a larger prospective, randomized trial (Infect Control Hosp Epidemiol2005;26:520-524).
Guidance on Public Reporting of Healthcare-Associated Infections: Recommendations of the Healthcare Infection Control Practices Advisory Committee
Authors: McKibben Linda , Horan Teresa C. , Tokars Jerome I. , Fowler Gabrielle , Cardo Denise M. , Pearson Michele L. , Brennan Patrick J. ,   Healthcare Infection Control Practices Advisory Committee
Published: April 2006

Consumer demand for healthcare information, including data about the performance of healthcare providers, has increased steadily during the past decade. Many state and national initiatives are under way to mandate or induce healthcare organizations to publicly disclose information regarding institutional and physician performance. Mandatory public reporting of healthcare performance is intended to enable stakeholders, including consumers, to make more informed choices on healthcare issues.

Public reporting of healthcare performance information has taken several forms. Healthcare performance reports (report cards and honor rolls) typically describe the outcomes of medical care in terms of mortality, selected complications, or medical errors and, to a lesser extent, economic outcomes. Increasingly, process measures (ie, measurement of adherence to recommended healthcare practices, such as hand hygiene) are being used as an indicator of how well an organization adheres to established standards of practice with the implicit assumption that good processes lead to good healthcare outcomes. National healthcare quality improvement initiatives, notably those of the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO), the Centers for Medicare & Medicaid Services (CMS), and the Hospital Quality Alliance, use process measures in their public reporting initiatives.
Using hidden Markov models and observed evolution to annotate viral genomes
Authors: McCauley Stephen , Hein Jotun
Published: April 2006

Motivation: ssRNA (single stranded) viral genomes are generally constrained in length and utilize overlapping reading frames to maximally exploit the coding potential within the genome length restrictions. This overlapping coding phenomenon leads to complex evolutionary constraints operating on the genome. In regions which code for more than one protein, silent mutations in one reading frame generally have a protein coding effect in another. To maximize coding flexibility in all reading frames, overlapping regions are often compositionally biased towards amino acids which are 6-fold degenerate with respect to the 64 codon alphabet. Previous methodologies have used this fact in an ad hoc manner to look for overlapping genes by motif matching. In this paper differentiated nucleotide compositional patterns in overlapping regions are incorporated into a probabilistic hidden Markov model (HMM) framework which is used to annotate ssRNA viral genomes. This work focuses on single sequence annotation and applies an HMM framework to ssRNA viral annotation. A description of how the HMM is parameterized, whilst annotating within a missing data framework is given. A Phylogenetic HMM (Phylo-HMM) extension, as applied to 14 aligned HIV2 sequences is also presented. This evolutionary extension serves as an illustration of the potential of the Phylo-HMM framework for ssRNA viral genomic annotation.

Results: The single sequence annotation procedure (SSA) is applied to 14 different strains of the HIV2 virus. Further results on alternative ssRNA viral genomes are presented to illustrate more generally the performance of the method. The results of the SSA method are encouraging however there is still room for improvement, and since there is overwhelming evidence to indicate that comparative methods can improve coding sequence (CDS) annotation, the SSA method is extended to a Phylo-HMM to incorporate evolutionary information. The Phylo-HMM extension is applied to the same set of 14 HIV2 sequences which are pre-aligned. The performance improvement that results from including the evolutionary information in the analysis is illustrated.

Availability: We implement the SSA method in the MATLAB programming language and provide the source code at . Additional supplementary material referred to in the text is available on the same webpage.

Contact:  mccauley@stats.ox.ac.uk

Supplementary Information: Supplementary data are available at
Orientational director effects in nematic liquid crystals with small Ericksen number
Authors: Atkinson C , Pereira P.J.S
Published: April 2006

Orientational director effects in nematic liquid crystals with small Ericksen number are investigated. The director field is disturbed by a semi-infinite plate ony=0 andand moving with a constant velocityU. Strong anchoring conditions at the plate are assumed. The resulting equations are a system of nonlinear partial differential equations for a nematic in the one elastic constant approximation. These equations are reduced to a coupled set of nonlinear ordinary differential equations by a suitable transformation. No such transformation seems possible for the many elastic constant case. The resulting equations are solved using analytical methods and strict bounding solutions obtained. These strict analytical solutions are compared with Picard iterated solutions.
Expansion formulae for the homogenized determinant of anisotropic checkerboards
Authors: Briane Marc , Capdeboscq Yves
Published: April 2006

In this paper, some effective properties of anisotropic four-phase periodic checkerboards are studied in two-dimensional electrostatics. An explicit low-contrast second-order expansion for the determinant of the effective conductivity is given. In the case of a two-phase checkerboard with commuting conductivities, the expansion reduces to an explicit formula for the effective determinant (valid for any contrast) as soon as the second-order term vanishes. Such an explicit formula cannot be extended to four-phase checkerboards. A counter-example with high-contrast conductivities is provided. The construction of the counter-example is based on a factorization principle, due to Astala & Nesi, which allows us to pass from an anisotropic four-phase square checkerboard to an isotropic one with the same effective determinant.
Aggressive behaviour affects selection on morphology by influencing settlement patterns in a passerine bird
Authors: Duckworth Renée A
Published: April 2006

The importance of behaviours as instigators or inhibitors of evolutionary change remains largely unresolved and this is in part because there are very few empirical examples of how behaviours affect evolutionary processes. By determining the environment of breeding, aggressive interactions over territories have the potential to strongly impact selection pressures experienced by individuals. Western bluebirds (Sialia mexicana) provide a unique opportunity to investigate the evolutionary importance of aggression, since their highly variable breeding habitat favours distinct foraging techniques and they also compete aggressively for nest boxes, a resource that is easy to manipulate. Here, I show experimentally that more aggressive males compete more effectively for territories with a high density of nest boxes and, as a consequence, aggressive and non-aggressive males are sorted into distinct breeding habitats that differ in the strength of selection on morphological traits. Specifically, males with longer tails and tarsi were favoured in open habitats where high agility is required to forage efficiently, whereas in forested habitats, where agility is less important, selection was weak. These results show that aggression can affect selection on a local scale by determining individual settlement patterns. More generally, because territorial interactions are important across a wide variety of taxa, these results suggest that aggressive behaviour has the potential to impact the evolutionary trajectory of many animal populations.
Maternal effects due to male attractiveness affect offspring development in the zebra finch
Authors: Gilbert L , Williamson K.A , Hazon N , Graves J.A
Published: April 2006

Maternal effects occur when offspring phenotype is influenced by environmental factors experienced by the mother. Mothers are predicted to invest differentially in offspring in ways that will maximize offspring fitness depending on the environment she expects them to encounter. Here, we test for maternal effects in response to mate attractiveness on offspring developmental traits in the zebra finch
Taeniopygia guttata
. We controlled for parental genetic quality by manipulating male attractiveness using coloured leg rings and by randomly assigning mating pairs. The potential confounding effect of differential nestling care was controlled for by cross-fostering clutches and by allowing for variance due to foster father attractiveness in general linear models. We found a difference in egg mass investment between attractiveness groups and, importantly, we found that all of the offspring traits we measured varied with the attractiveness of the father. This provides strong evidence for maternal effects in response to mate attractiveness. Furthermore, due to the experiment design, we can conclude that these effects were mediated by differential investment of egg resources and not due to genetic differences or differences in nestling care.
Activation of the mTOR signalling pathway is required for pancreatic growth in protease‐inhibitor‐fed mice
Authors: Crozier Stephen J. , Sans M. Dolors , Guo LiLi , D'Alecy Louis G. , Williams John A.
Published: April 2006

Cholecystokinin (CCK)‐induced pancreatic growth in mice involves parallel increases in DNA and protein. The mammalian target of rapamycin (mTOR) signalling pathway regulates mRNA translation and its activation is implicated in growth of various tissues. The aim of this study was to elucidate whether mTOR activation is required for pancreatic growth in a mouse model of increased endogenous CCK release. In mice fed chow containing the synthetic protease inhibitor camostat, protein synthetic rates and phosphorylation of two downstream targets of mTOR, eukaryotic initiation factor 4E binding protein 1 (4E‐BP1) and the ribosomal protein S6 (S6), increased in comparison with fasted controls. The camostat‐induced increases in protein synthesis and 4E‐BP1 and S6 phosphorylation were almost totally abolished by administration of the mTOR inhibitor rapamycin 1 h prior to camostat feeding. In contrast, the phosphorylation of ERK1/2 and JNK and the expression of the early response genes c‐jun, c‐fos, ATF3 and egr‐1 induced by camostat feeding were not affected by rapamycin. In mice fed camostat for 7 days, the ratio of pancreatic to body weight increased by 143%, but when rapamycin was administered daily this was reduced to a 22% increase. Changes in pancreatic mass were paralleled by protein and DNA content following camostat feeding and rapamycin administration. Moreover, while BrdU incorporation, an indicator of DNA synthesis, was increased to 448% of control values after 2 days of camostat feeding, rapamycin administration completely inhibited this increase. We conclude that the mTOR signalling pathway is required for CCK‐induced cell division and pancreatic growth.
Frequency–current relationships of rat hindlimb α‐motoneurones
Authors: Button Duane C. , Gardiner Kalan , Marqueste Tanguy , Gardiner Phillip F.
Published: April 2006

The purpose of this study was to describe the frequency–current (f–I) relationships of hindlimb α‐motoneurones (MNs) in both anaesthetized and decerebrate rats in situ. Sprague–Dawley rats (250–350 g) were anaesthetized with ketamine and xylazine (KX) or subjected to a precollicular decerebration prior to recording electrophysiological properties from sciatic nerve MNs. Motoneurones from KX‐anaesthetized rats had a significantly (P < 0.01) hyperpolarized resting membrane potential and voltage threshold (Vth), increased rheobase current, and a trend (P= 0.06) for a smaller after‐hyperpolarization (AHP) amplitude compared to MNs from decerebrate rats. In response to 5 s ramp current injections, MNs could be categorized into four f–I relationship types: (1) linear; (2) adapting; (3) linear + sustained; and (4) late acceleration. Types 3 and 4 demonstrated self‐sustained firing owing to activation of persistent inward current (PIC). We estimated the PIC amplitude by subtracting the current at spike derecruitment from the current at spike recruitment. Neither estimated PIC nor f–I slopes differed between fast and slow MNs (slow MNs exhibited AHP half‐decay times > 20 ms) or between MNs from KX‐anaesthetized and decerebrate rats. Motoneurones from KX‐anaesthetized rats had significantly (P < 0.02) hyperpolarized ramp Vth values and smaller and shorter AHP amplitudes and decay times compared to MNs from decerebrate rats. Pentobarbitone decreased the estimated PIC amplitude and almost converted the f–I relationship from type 3 to type 1. In summary, MNs of animals subjected to KX anaesthesia required more current for spike initiation and rhythmic discharge but retained large PICs and self‐sustained firing. The KX‐anaesthestized preparation enables direct recording of PICs in MNs from intact animals.
Activity‐dependent synaptic plasticity in the supraoptic nucleus of the rat hypothalamus
Authors: Panatier Aude , Gentles Stephen J. , Bourque Charles W. , Oliet Stéphane H. R.
Published: April 2006

Activity‐dependent long‐term synaptic changes were investigated at glutamatergic synapses in the supraoptic nucleus (SON) of the rat hypothalamus. In acute hypothalamic slices, high frequency stimulation (HFS) of afferent fibres caused long‐term potentiation (LTP) of the amplitude of AMPA receptor‐mediated excitatory postsynaptic currents (EPSCs) recorded with the whole‐cell patch‐clamp technique. LTP was also obtained in response to membrane depolarization paired with mild afferent stimulation. On the other hand, stimulating the inputs at 5 Hz for 3 min at resting membrane potential caused long‐term depression (LTD) of excitatory transmission in the SON. These forms of synaptic plasticity required the activation of NMDA receptors since they were abolished in the presence of d‐AP5 or ifenprodil, two selective blockers of these receptors. Analysis of paired‐pulse facilitation and trial‐to‐trial variability indicated that LTP and LTD were not associated with changes in the probability of transmitter release, thereby suggesting that the locus of expression of these phenomena was postsynaptic. Using sharp microelectrode recordings in a hypothalamic explant preparation, we found that HFS also generates LTP at functionally defined glutamatergic synapses formed between the organum vasculosum lamina terminalis and SON neurons. Taken together, our findings indicate that glutamatergic synapses in the SON exhibit activity‐dependent long‐term synaptic changes similar to those prevailing in other brain areas. Such forms of plasticity could play an important role in the context of physiological responses, like dehydration or lactation, where the activity of presynaptic glutamatergic neurons is strongly increased.
Extrusion of Ca2+ from mouse motor terminal mitochondria via a Na+–Ca2+ exchanger increases post‐tetanic evoked release
Authors: García‐Chacón Luis E. , Nguyen Khanh T. , David Gavriel , Barrett Ellen F.
Published: April 2006

Mitochondria sequester much of the Ca2+ that enters motor nerve terminals during repetitive stimulation at frequencies exceeding 10–20 Hz. We studied the post‐stimulation extrusion of Ca2+ from mitochondria by measuring changes in matrix [Ca2+] with fluorescent indicators loaded into motor terminal mitochondria in the mouse levator auris longus muscle. Trains of action potentials at 50 Hz produced a rapid increase in mitochondrial [Ca2+] followed by a plateau, which was usually maintained after the end of the stimulus train and then slowly decayed back to baseline. Increasing the Ca2+ load delivered to the terminal by increasing the number of stimuli (from 500 to 2000) or the stimulation frequency (from 50 to 100 Hz), by increasing bath [Ca2+], or by prolonging the action potential with 3,4‐diaminopyridine (100 μm) prolonged the post‐stimulation decay of mitochondrial [Ca2+] without increasing the amplitude of the plateau during stimulation. Inhibiting the opening of the mitochondrial permeability transition pore with cyclosporin A (5 μm) had no significant effect on the decay of mitochondrial [Ca2+]. Inhibition of the mitochondrial Na+–Ca2+ exchanger with CGP‐37157 (50 μm) dramatically prolonged the post‐stimulation decay of mitochondrial [Ca2+], reduced post‐stimulation residual cytosolic [Ca2+], and reduced the amplitude of endplate potentials evoked after the end of a stimulus train in the presence of both low and normal bath [Ca2+]. These findings suggest that Ca2+ extrusion from motor terminal mitochondria occurs primarily via the mitochondrial Na+–Ca2+ exchanger and helps to sustain post‐tetanic transmitter release at mouse neuromuscular junctions.
Revisiting elementary quantum mechanics with the BenDaniel-Duke boundary condition
Authors: Singh Vijay A. , Kumar Luv
Published: April 2006

The past decade has seen an upsurge of interest in quantum dots and nanostructures. These are essentially structures of size 1to10nm. We discuss a simplified model of a quantum dot in which we employ the effective mass approximation and the BenDaniel-Duke boundary condition. The latter accounts for the fact that the effective carrier mass inside the well, mi, is different from the mass outside, m0. The energies and the charge distributions in the nanostructure are determined by the mass discontinuity factor β=mi∕m0. The charge density at the interface becomes larger as β→0. We propose a novel quantum scale σ∼β2V0L2, where V0 is the barrier height and L is the well size. The scale σ represents a mass modified potential strength. An asymptotic analysis shows that the charge densities and energies of the carrier depend simply on σ. We also propose a definition of the penetration depth analogous to the one proposed by Garrett. Our study of tunneling reveals that the one-dimensional analog of the Ramsauer-Townsend resonances becomes increasingly sharp and well defined as β→0.
Unified derivation of Johnson and shot noise expressions
Authors: Callegaro Luca
Published: April 2006

Shot noise and Johnson noise in electrical circuits are usually introduced by referring to completely separate physical models and derivations. We derive Johnson and shot noise expressions from the same physical model, an ideal tunnel junction, to show the deep connection between the two types of noise. The derivation uses concepts of quantum mechanics, thermodynamics, and signal processing.