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Biomedical subjects

R B Leonard

Publications and source records attributed to R B Leonard.

At least 19 recordsLinked to original sources
PubMed1998

Investigation of an outbreak of vancomycin-resistant Enterococcus faecium in a low prevalence university hospital.

BACKGROUND: Until 1995, there were no cases of vancomycin resistant enterococcus (VRE) identified at our university hospital. From May 1995 to August 1996, we investigated a cluster of 10 cases of phenotypic class Van B Enterococcus faecium. METHODS: Patients were matched with controls who were on the same unit for at least 7 days prior to the case developing VRE. Control patients were age and sex matched if possible, and had duration of hospitalization at least as long as the number of days it took the patient to become VRE positive. We analyzed 16 independent risk factors using Epi-info version 6. Environmental cultures were obtained in the MICU where 5 of the patients were located. All 10 patient isolates and environmental isolates were analyzed by pulsed field gel electrophoresis (PFGE). RESULTS: PFGE confirmed the genetic relatedness of all 10 patient isolates and environmental isolates. The VRE-positive group was more likely to be immunosuppressed and to have exposure to 3 physicians. In the MICU, significant, P < 0.05) risk factors for VRE were higher Apache scores, location adjacent to a VRE case, duration of vancomycin and amino-glycoside use, duration of invasive catheter use, and diarrhea. Among the VRE-positive environmental cultures was a blood pressure cuff wash that was used on several patients. CONCLUSION: We hypothesize that a VRE strain was introduced into our hospital environment and was spread by personnel or contaminated equipment. As a consequence of this study, a hospital-wide VRE policy was implemented.

Adolescent↗
PubMed1997

Use of calcium-binding proteins to map inputs in vestibular nuclei of the gerbil.

We wished to determine whether calbindin and/or calretinin are appropriate markers for vestibular afferents, a population of neurons in the vestibular nuclear complex, or cerebellar Purkinje inputs. To accomplish this goal, immunocytochemical staining was observed in gerbils after lesions of the vestibular nerve central to the ganglion, the cerebellum, or both. Eleven to fourteen days after recovery, the brain was processed for immunocytochemical identification of calretinin and calbindin. After lesion of the vestibular nerve, no calretinin staining was seen in any of the vestibular nuclei except for a population of intrinsic neurons, which showed no obvious change in number or staining pattern. Calbindin staining was reduced in all nuclei except the dorsal part of the lateral vestibular nuclei. The density of staining of each marker, measured in the magnocellular medial vestibular nucleus, was significantly reduced. After the cerebellar lesion, no differences in calretinin staining were noted. However, calbindin staining was greatly reduced in all nuclei. The density of staining, measured in the caudal medial vestibular nucleus, was significantly lower. After a combined lesion of the cerebellum and vestibular nerve, the distribution and density of calretinin staining resembled that after vestibular nerve section alone, whereas calbindin staining was no longer seen. This study demonstrates that calretinin and calbindin are effective markers for the identification of vestibular afferents.

Animals↗
PubMed1997

Characterization of endemic strains of Shigella sonnei by use of plasmid DNA analysis and pulsed-field gel electrophoresis to detect patterns of transmission.

Shigellosis is hyperendemic in Utah. Most isolates are Shigella sonnei, making it difficult to identify epidemiologic clustering. To better define transmission, molecular markers and epidemiologic data were examined for 90 cases. Plasmid analysis and pulsed-field gel electrophoresis (PFGE) of the S. sonnei isolates identified 11 and 4 patterns, respectively. Plasmid pattern I infections occurred in 8 day care centers over a 6-month period, suggesting spread between centers. Plasmid pattern III was isolated from children at 3 additional centers and pattern IV was associated with another day care center, suggesting different outbreaks. By PFGE, plasmid groups I and XI appeared identical, as were plasmid groups II and V; plasmid group X had a unique pattern. Plasmid groups III, IV, and VII-IX were closely related PFGE subtypes. Both plasmid analysis and PFGE allow better characterization of S. sonnei transmission patterns of "endemic" strains and could lead to improved control measures.

DNA, Bacterial↗
PubMed1997

Rapid lysis of gram-positive cocci for pulsed-field gel electrophoresis using achromopeptidase.

To adapt pulsed-field gel electrophoresis (PFGE) to a busy clinical laboratory, we evaluated the use of achromopeptidase (ACP) as the sole agent for lysis of a variety of gram-positive cocci. Growth in an appropriate broth media was adjusted to a 3.0 McFarland density before aliquotting for washing and plug preparation. ACP incorporated into the agarose plugs, or added to the buffer solution, lysed cells in < 1 h when suspended in a Tris-NaCl buffer. Two 30-min washes in a Tris-EDTA buffer were sufficient to remove cellular debris without additional deproteination. Final PFGE results were obtained in approximately 48 h, including the initial broth subculturing.

Bacterial Typing Techniques↗
PubMed1996

Medical support for mass gatherings.

Fairs, concerts, parades, and rallies are some of the many events that cause large numbers of people to gather in one place. Whether the event lasts a day or a week, it is evident that the people attending may require organized medical care. Most of the medical needs are minor, but cardiac arrests and other serious medical problems, including trauma, must be dealt with by the medical team. Careful planning and integration of emergency physician efforts with local hospitals and the emergency medical services system allow for an optimal delivery of health care, from the routine incident to a mass-casualty event.

Age Factors↗
PubMed1996

Rapid detection of the staphylococcal mecA gene from BACTEC blood culture bottles by the polymerase chain reaction.

A rapid polymerase chain reaction (PCR) method for the direct detection of the staphylococcal mecA gene from BACTEC blood culture bottles (Becton Dickinson, Sparks, MD) was developed. Published primer sequences and sample preparation using Achromopeptidase for cell lysis were adapted to the use of the Idaho Technology Air Thermocycler 1605 (Idaho Technologies, Idaho Falls, ID). The method was validated with 80 strains of coagulase-positive and coagulase-negative geographically diverse methicillin-resistant and susceptible isolates of staphylococci. There was a 100% correlation between the PCR results and the results of standard susceptibility testing methods. From BACTEC 9240 blood cultures, mixed aliquots of blood and broth containing gram-positive cocci in clusters were centrifuged at low speed to sediment red blood cells. After additional centrifugation and wash steps, PCR was performed on the resuspended pellet. The turnaround time from initial Gram stain detection of positive BACTEC bottles to PCR amplicon detection by agarose gel electrophoresis is less than 3 hours. In a clinical evaluation of 181 blood culture isolates, there was a 99% correlation with standard susceptibility results for Staphylococcus aureus. Discrepant results for Staphylococcus aureus isolates were verified by a Mueller Hinton plate supplemented with 6 microg/mL of oxacillin and 2% sodium chloride. For coagulase-negative staphylococci, the PCR method detected an additional seven resistant isolates that were reported by the Vitek as susceptible. Coagulase-negative staphylococcal susceptibility results that were in disagreement with the PCR assay were confirmed by the disk-diffusion method. This procedure is accurate, rapid and fits well into laboratory work flow. Rapid detection of the mecA gene on positive blood culture vials has become a routine test in the authors' clinical microbiology laboratory.

Bacterial Proteins↗
PubMed1995

Comparison of "gram-sure" with vancomycin disks in distinguishing between gram-negative and gram-positive rods.

A study was performed to compare Gram-Sure (JRGA Diagnostics, Rancho Dominguez, CA) with vancomycin disk susceptibility (5 micrograms and 30 micrograms) for clarification of the Gram reaction. Eighty-eight isolates representing 14 gram-negative and gram-positive genera were tested. Gram-Sure was superior to vancomycin susceptibility as a predictor of the Gram reaction in a select group of difficult organisms.

Bacillaceae Infections↗
PubMed1995

Comparison of MIDI Sherlock system and pulsed-field gel electrophoresis in characterizing strains of methicillin-resistant Staphylococcus aureus from a recent hospital outbreak.

An outbreak of methicillin-resistant Staphylococcus aureus infections at the University of Utah Health Sciences Center occurred over a 7-month period. While the isolates phenotypically appeared to be similar in gross morphology and have similar Vitek antibiotic susceptibility patterns, two additional methods of strain characterization were evaluated to enhance the epidemiological investigation: pulsed-field gel electrophoresis and gas chromatography with the MIDI Sherlock system. Sherlock uses gas chromatography to qualitatively and quantitatively analyze the cellular fatty acid composition of organisms and creates two-dimensional plots based on principal-component analysis to define groups of closely related organisms. All isolates were also evaluated by digesting their chromosomal DNAs with the low-frequency-cutting enzyme SmaI and separating the restriction fragments by contour-clamped homogeneous electric field gel electrophoresis. Sample preparation for this pulsed-field gel electrophoresis included a novel cell lysis procedure involving achromopeptidase, greatly reducing the turnaround time. Isolates tested were recovered from the following: 45 suspected outbreak patients, 6 hospitalized patients believed to be unrelated to the outbreak, 6 patients from outside the hospital, and one health care practitioner implicated in the outbreak. Of 45 phenotypically similar suspect strains, 43 clustered tightly on the Sherlock two-dimensional plot. All outbreak patient isolates were also identical by pulsed-field gel electrophoresis with the exception of the same two outliers identified by Sherlock. In this epidemiologic investigation, we found an excellent correlation between the Sherlock and pulsed-field gel electrophoresis results for strain characterization of methicillin-resistant S. aureus.

Bacterial Typing Techniques↗
PubMed1994

Vestibulo-oculomotor connections in an elasmobranch fish, the Atlantic stingray, Dasyatis sabina.

In elasmobranch fishes, including the Atlantic stingray, the medial rectus muscle is innervated by the contralateral oculomotor nucleus. This is different from most vertebrates, in which the medial rectus is innervated by the ipsilateral oculomotor nucleus. This observation led to the prediction that the excitatory vestibulo-extraocular motoneuron projections connecting each semicircular canal to the appropriate muscle should use a contralateral projection from the vestibular nuclei to the motoneurons. This hypothesis was examined in the Atlantic stingray by injecting horseradish peroxidase unilaterally into the oculomotor nucleus. It was found that vestibulo-oculomotor projections arise from the ipsilateral anterior octaval nucleus and the contralateral descending octaval nucleus. The same pattern was observed when the trochlear nucleus was involved in the injection. There were no cells labeled in the region of the abducens nucleus, and no candidate for a nucleus prepositus hypoglossus was identified. The presence of compensatory eye movements, the directional sensitivity of the semicircular canals, the location of the motoneurons innervating each eye muscle, and our results indicate that the excitatory input to the extraocular motoneurons is derived from the contralateral descending octaval nucleus, and the inhibitory input is derived from the ipsilateral anterior octaval nucleus. The absence of both abducens internuclear interneurons and a nucleus prepositus hypoglossus suggests that eye movements, particularly those in the horizontal plane, are controlled differently in elasmobranchs than in other vertebrates examined to date.

Animals↗
PubMed1994

Molecular evidence of person-to-person transmission of a pigmented strain of Corynebacterium striatum in intensive care units.

During a 14-month period, a unique strain of Corynebacterium striatum that produces a diffusible brown pigment was isolated from purulent sputa of nine patients and from nonrespiratory sites of two additional patients. Seven nonpigmented clinical isolates from the same period and three reference strains of C. striatum were compared with the brown isolates. Most patients had multiple sputum cultures with no coryneforms before the brown strain emerged, suggesting that the organism was hospital acquired. DNA restriction fragment patterns and Southern hybridization with the att site probe of Corynebacterium diphtheriae indicated that the brown isolates were a single strain which was distinct from the heterogeneous nonpigmented strains. A common source for the brown C. striatum was not recognized, although all of these patients were located in two adjoining intensive care units. All of the brown isolates, three of the nonpigmented clinical isolates, and two reference strains had positive CAMP reactions with Staphylococcus aureus, which has not been reported for C. striatum prior to this study.

Bacterial Typing Techniques↗
PubMed1993

The octavolateral systems in the stingray, Dasyatis sabina. I. Primary projections of the octaval and lateral line nerves.

The central projections of the electrosensory, mechanosensory, and octaval nerves of the Atlantic stingray were examined by transganglionic transport of horseradish peroxidase. Particular attention was paid to the relation of the projections to cell plates C1 and C2, and to a newly described cell plate, C3. The electroreceptors in the stingray are found in three groups on the dorsal and ventral sides of the body. The electroreceptors are represented topographically on the ipsilateral dorsal nucleus. Those of the rostral part of the head and pectoral fins are represented on the rostroventral part of the nucleus, and those on the caudal part of the head and the pectoral fin on the dorsocaudal part of the nucleus. Mechanosensory lateral line afferents terminate within the ipsilateral intermediate and caudal nuclei, and the lateral granular mass of the vestibulocerebellum. Anterior lateral line afferents also project to the magnocellular octaval nucleus. A topographic representation of the mechanosensory lateral line periphery is present on the intermediate and caudal nuclei. Mechanoreceptors on the trunk are represented laterally and those on the head medially. The terminal field of the anterior lateral line afferents on the intermediate nucleus surrounds cell plates C1 and C2. The anterior lateral line afferents also project to the medial part of the lateral granular mass, whereas the posterior lateral line afferents project to the lateral portion. Sparse projections of anterior lateral line afferents to the periventricular octaval nucleus were also observed. The octaval nerve afferents terminate largely within the octaval column. Octaval nerve projections were also observed to the reticular formation, the periventricular octaval nucleus, the deep cerebellar nucleus, the vestibulocerebellum, particularly the lower lip and medial granular mass, and the intermediate nucleus. A sparse projection to cell plate C3 was found. The relation between cell plates C1 and C2 and the anterior lateral line afferents suggests that these cell plates are related to processing lateral line information. While the relationship between cell plate C3 and the octaval afferents is not strong, the sparse octaval projection C3 receives suggests that it is relaying octaval information.

Afferent Pathways↗
PubMed1993

Analysis of medical treatment at a field hospital following Hurricane Andrew, 1992.

STUDY OBJECTIVE: To determine what medical care was required of a special operations response team by a community devastated by a major hurricane. STUDY DESIGN: Retrospective analysis of 1,544 patient encounter forms generated at a field hospital set up in Homestead, Florida, after Hurricane Andrew in August 1992 and staffed by the special operations response team from Forsyth County, North Carolina. TYPE OF PARTICIPANTS: All persons presenting for treatment. RESULTS: One thousand two hundred three adult patients and 336 pediatric patients were seen by the special operations response team. Only five of the injuries treated were due directly to the hurricane, whereas 285 of the treated injuries were sustained during clean-up activities. Most of the care provided was routine medical care denied the citizens due to the loss of their physicians' offices and clinics. Supplies of tetanus toxoid, antibiotics, and insulin were depleted in 24 hours. Resupplying these items and acquiring other medication to refill prescriptions constituted a pressing problem. CONCLUSION: The primary function of medical personnel responding to an area hit by a major hurricane will be to provide general medical care. Any trauma encountered will be primarily due to clean-up activities and not due to the hurricane itself. Responding medical personnel should plan on providing their own food and water for the first 72 hours and be well stocked with antibiotics, tetanus toxoid, and insulin.

Adult↗
PubMed1993

Pursuit of the Corynebacterium striatum type strain.

The description of Corynebacterium striatum (Chester 1901) Eberson 1918AL in Bergey's Manual of Systematic Bacteriology has many inconsistencies with the identification scheme from the Centers for Disease Control and Prevention. We have studied the four C. striatum reference strains available from the American Type Culture Collection and the National Collection of Type Cultures and found that they fit the Centers for Disease Control and Prevention description of this species. However, it appears that the wrong strains were deposited for this species, because none of the reference strains fits the descriptions in the original publications. This is a substantial case for declaring it a nomen dubium, but the name could be rescued if a careful search reveals a strain that was used in making the original description. It is hoped that some readers may have the missing strains labeled with the early names Bacillus striatus, Bacillus flavidus, or Corynebacterium flavidum.

Artifacts↗
PubMed1993

Evidence of multiple taxa within commercially available reference strains of Corynebacterium xerosis.

Attempts to identify coryneform isolates resembling Corynebacterium xerosis can lead clinical microbiologists to identification schemes with conflicting descriptions which result in confusing C. xerosis with Corynebacterium striatum. For the present study we purchased all available American Type Culture Collection and National Collection of Type Cultures reference cultures of C. xerosis (n = 10) and C. striatum (n = 4) and analyzed them as follows: (i) analysis of biochemical reactions in conventional tests and in the Rapid CORYNE system, (ii) whole-cell fatty acid analysis by using the gas-liquid chromatography research software of Microbial ID, Inc., and (iii) analysis of DNA homology in dot blot hybridizations. Three C. xerosis strains were indistinguishable from the C. striatum strains in whole-cell fatty acid analyses and DNA hybridizations and shared very similar biochemical reactions. The remaining seven strains of C. xerosis clustered into five groups on the basis of fatty acid patterns, DNA hybridizations, and biochemical tests. No reference strain of C. striatum fit the species description in Bergey's Manual of Systematic Bacteriology. The type strains of both C. striatum and C. xerosis fit their respective descriptions by the Centers for Disease Control and Prevention. This study suggests that the 10 commercially available reference strains of C. xerosis represent six different taxa which should be assigned to new species.

Bacterial Typing Techniques↗
PubMed1993

Hazardous materials accidents: initial scene assessment and patient care.

Hazardous materials, i.e., chemicals that are toxic, corrosive, flammable, or explosive, are a ubiquitous aspect of modern life. They are manufactured throughout the United States, shipped by truck, train, barge, and pipeline, and stored at a wide variety of locations, including factories, military bases, and warehouses. Accidents involving hazardous materials present an added dimension of danger to emergency personnel arriving first at the scene, and have the potential to produce chemically contaminated patients who require special medical treatment. Personnel arriving first at the scene must understand how to evaluate the scene for fast and safe mitigation without endangering themselves. Chemically contaminated patients require prompt treatment, which, for optimal outcome, must begin at the scene. Although frequently the identification of the hazardous materials involved is not known initially, emergency personnel may safely provide medical care to the victims by understanding and following the principles of hazardous materials accidents and the pathophysiology of chemical injuries as presented in this paper.

Accidents, Traffic↗
PubMed1992

Variations in cerebellar morphology of the Atlantic stingray, Dasyatis sabina.

The cerebellar corpus of the Atlantic stingray consists of an anterior lobe which is divided into rostral and caudal lobules, and a posterior lobe. The long axis of the posterior lobe and rostral lobule of the anterior lobe both lie along the midline, whereas the orientation of the caudal lobule varies. We examined this variation in 127 animals. In 52% the long axis of the caudal lobule lay on the right of the midline, in 21% it was on the left, and in 27% across the midline. While this distribution is not random, it is not related to size or sex. It is proposed that the observed variation is the reflection of variation in the cerebellar developmental program.

Animals↗