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Cellulitis that is not caused by a wound or catheter most often occurs on the legs and feet.
Less common bacteria varieties can cause infection after animal bites, puncture wounds through wet shoes, or wounds exposed to freshwater lakes, aquariums, or swimming pools. Erysipelas, a skin infection that causes raised, firm, bright red patches of skin — Usually, it is caused by Streptococcus bacteria.
Necrotizing fasciitis, also known as "flesh-eating strep" — This is an infection of the tissues below the skin, rather than the skin itself. Many people who develop cellulitis have no other medical problems and no obvious injury or skin damage that allowed the infection to occur. Your doctor can usually diagnose cellulitis based on your recent medical history, your symptoms and a physical examination. In most cases, your doctor is not able to specifically tell you what bacteria type has caused your infection. How long cellulitis lasts depends on the extent of the cellulitis, the bacteria that caused the infection and your general health.
Treat minor skin wounds promptly — Gently wipe away dirt, wash with antibiotic soap, apply antibiotic ointment and cover with a clean bandage.
Seek medical attention — Medical attention is needed for all deep puncture wounds and animal bites and for all deep wounds involving a joint, hand or foot. If you have mild cellulitis, you can usually treat it at home with antibiotics taken by mouth. If you have severe cellulitis, you may need to be treated in the hospital with antibiotics given intravenously (into a vein). Community-acquired MRSA infections may worsen despite antibiotic treatment, because the antibiotics that are most commonly selected to treat cellulitis do not reliably kill this bacteria. In most cases, symptoms of cellulitis begin to improve within 24 to 48 hours after starting treatment with appropriate antibiotics.
Disclaimer: This content should not be considered complete and should not be used in place of a call or visit to a health professional. The easiest way to lookup drug information, identify pills, check interactions and set up your own personal medication records. The bacteria called non-typeable Haemophilus influenzae are a common cause of infection in the upper respiratory tract. Researchers from the University of Southern California and the Oak Crest Institute of Science have discovered the link between antibiotics and bacterial biofilm formation leading to chronic lung, sinus and ear infections. During the study, non-typeable Haemophilus influenzae (NTHi) bacteria a common pathogen of humans was exposed to non-lethal doses of ampicillin, a class of antibiotics commonly used to treat respiratory, sinus and ear infections, or other beta-lactam antibiotics.
Biofilms are highly structured communities of microorganisms that attach to one another and to surfaces. Webster believes modern medicine needs to find ways of detecting and treating biofilm infections before the bacteria are able to form these protective structures. A group of researchers from the US has moved a step closer to preventing infections of the common hospital pathogen, Staphylococcus aureus, by revealing the mechanisms that allow the bacteria to rapidly clog up medical devices. A relationship that has lasted for 100 million years is at serious risk of ending, due to the effects of environmental and climate change. The simple act of water droplets landing on a leaf causes an elaborate response inside of plants, scientists at The University of Western Australia have found. In the animal kingdom, sperm usually are considerably smaller than eggs, which means that males can produce far more of them.
Researchers can build complex, nanometer-scale structures of almost any shape and form, using strands of DNA. Bacteria break through the skin's protective outer layer, typically at the site of an injury, such as a cut, puncture, sore, burn or bite. Erysipelas occurs most often on an arm or leg that has been damaged by previous surgery or is chronically swollen due to poor lymph flow (lymphedema). Without proper antibiotic treatment, some forms of cellulitis can cause serious complications within a few days, even in otherwise healthy people.
Your doctor will choose a specific antibiotic depending on the site of your cellulitis and the likely cause of your infection.
However, keep in touch with your doctor to be sure that the infection is improving as expected. If within the first two or three days of treatment you don't have obvious improvement in your skin pain, redness, and swelling, or if you develop blisters or pus on the surface of your skin rash, contact your doctor immediately. Call your doctor promptly if you get a deep puncture wound, especially on a hand or foot, or if you are bitten by an animal or human. Always take all the antibiotics prescribed by your doctor, even if you think your infection has been cured. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.
The study results, published in the current issue of PLOS ONE, illustrate how bacterial biofilms can actually thrive, rather than decrease, when given low doses of antibiotics. The dose of the antibiotic was not enough to kill the bacteria which allowed the bacteria to react to the antibiotic by producing glycogen, a complex sugar often used by bacteria as a food source, to produce stronger biofilms when grown in the laboratory.
Therefore, bacteria forced into forming stronger biofilms will become more difficult to treat and will cause more severe chronic infections.
The difficulties of treating biofilm infections, which can be up to 1,000 times more resistant to antibiotics, have prompted some physicians to propose a gradual move away from traditional antibiotic treatments and toward non-antibiotic therapies.
It often develops where there is edema (swelling), poor blood flow, or a skin rash that creates breaks in the skin, such as a fungus infection between the toes (athlete's foot). During the last several years, it has become more common for a strain of drug-resistant bacteria to cause cellulitis.
Because infection around the eye can spread to the brain if it is not quickly treated with antibiotics, periorbital cellulitis requires prompt medical attention.
Erysipelas also can develop on the face, typically across the bridge of the nose and upper cheeks. The area of warmth can be felt with the back of the hand, especially when compared to surrounding skin. Bloodstream infections (blood poisoning) from cellulitis are particularly dangerous in the very young and very old, as well as in those with weakened immune systems or abnormal heart valves.
At home, warm compresses, such as a warm, moist washcloth, and elevating the infected area can help.
The prognosis is generally good, but the condition can return, especially in people with poor circulation, chronic (long-term) swelling in the legs or skin that is in poor condition. This layer is highly protective for the organisms within it, and when new bacteria are produced they stay within the slimy layer. Adults will suffer protracted lung infections as the bacteria hunker down into their protective slime, and children will have repeated ear infections.


Once beneath the skin surface, bacteria multiply and make chemicals that cause inflammation in the skin.
This bacteria is named community-acquired methicillin-resistant staphylococcal aureus, or "community-acquired MRSA." Infections with this type of bacteria can lead to blistering of the skin or deep, more serious infections. There may be a spreading network of red streaks in the skin, caused by infection in the vessels that carry lymph (tissue fluid), as well as enlarged lymph nodes (swollen glands) near the area of infection. With the introduction of antibiotic-produced glycogen, the biofilms have an almost endless food source that can be used once antibiotic exposure has ended. What may appear to be antibiotic resistance when an infection does not clear up may actually be biofilms at work.
The opinions expressed are those of the authors and do not represent views of the Institute or the U.S. Department of Education. Instructional Materials Available for Download As part of the above-mentioned IES grant, we have developed a variety of instructional materials for teaching tree thinking to undergraduates. Versions of this booklet have been used by, and found effective for, (a) students of varying backgrounds recruited from a psychology subject pool, (b) students enrolled in an introductory biology course for science majors, and (3) biology majors enrolled in an upper-level biology class.
The laboratory has been used with the second two populations mentioned in conjunction with the instructional booklet.
Unpublished instructional booklet, Department of Psychology and Human Development, Vanderbilt University, Nashville, TN. Unpublished student laboratory booklet, Department of Psychology and Human Development, Vanderbilt University, Nashville, TN. Unpublished laboratory instructors' guide, Department of Psychology and Human Development, Vanderbilt University, Nashville, TN. For the past 9 years, I have been working with Kefyn Catley, an evolutionary biologist and science educator, to investigate college and high school students' understanding of cladograms, the most important tool that contemporary scientists use to reason about evolutionary relationships.
A cladogram is a type of hierarchical diagram that depicts hypotheses about nested sets of taxa that are supported by shared, evolutionarily novel characters called synapomorphies.
For example, the cladogram shown at the top of the page indicates that one synapomorphy for birds and alligators is that they both possess a gizzard.
That is, birds and alligators share a most recent common ancestor (MRCA) that evolved the novel character of possessing a gizzard.
A group of taxa consisting of the MRCA and all descendants of that ancestor is called a clade or monophyletic group.
Because of the nesting inherent in hierarchical diagrams, birds, alligators, and lizards also comprise a clade. And those three taxa plus mammals (represented by manatees and elephants in the cladogram above) constitute another clade, etc. Macroevolutionary processes operate at the level of species and above, resulting in the formation, radiation, and extinction of higher groups of taxa.
Tree thinking is the ability to understand and reason with evolutionary relationships depicted in cladograms (phylogenetic trees). Thus, inferences based on this classification scheme are likely to be more informative and to have greater practical value than inferences based on other criteria. Our research on tree thinking falls into three broad categories: (a) Influences of diagram design on interpretations of evolutionary relationships, (b) assessing and improving students' tree-thinking skills, and (c) effects of prior knowledge about taxonomic relationships on tree thinking. Studies in the first group have a primarily cognitive psychological basis, with strong implications for education.
Studies in the second group are rooted in science education while being informed by cognitive psychology. Studies in the third group reflect a more even mix of psychological and educational foundations. We have used a variety of different kinds of tasks, including those that require diagram comprehension, translation from one diagram format to another, and inference.
Our measures of performance include accuracy, types of errors made, written explanations (evidence cited) in support of one's responses, and patterns of eye movements. Consistent with a large cognitive psychological literature on diagram comprehension, we would expect students' interpretations of diagrams depicting evolutionary relationships to be influenced by how those diagrams are designed. Cladograms are typically drawn in one of two formats: rectangular trees (left diagram in the figure below) and diagonal ladders (right diagram in the figure below). In an analysis of the cladograms printed in a professional journal, Novick and Catley (2007) found that rectangular trees are by far the preferred format among evolutionary biologists: 83% vs. In high school and biology textbooks, however, the diagonal format was found to occur slightly more often than the rectangular format: 59% vs. We found that students particularly had trouble understanding the structure of the diagonal format, and this difficulty was especially pronounced for students with weaker backgrounds in biology. We hypothesized that this difficulty stems from the Gestalt principle of good continuation, which makes it difficult to extract the critical information about hierarchical levels from diagonal format cladograms. Examination of the errors students made in drawing diagonal format cladograms and in translating from the diagonal to the rectangular format supported this hypothesis. A preliminary report of this research may be found in Novick and Catley (2006); the full report is in Novick and Catley (2007).
The method we tested was to add a synapomorphy to mark each branching point in such cladograms. As reported in Novick, Catley, and Funk (2010), this manipulation greatly improved students' ability to translate diagonal cladograms to the rectangular format. One factor is students' strong bias to scan cladograms from left to right, following their highly practiced directional pattern for reading written text. The second factor is their preference to scan along the main diagonal line at the base of the diagonal cladogram. These two factors in combination mean that students scan diagonal cladograms such as that shown in the above figure from left to right and from bottom to top, which impairs their ability to uncover the correct pattern of nesting. If the diagrams are simply reflected so that the main diagonal runs from the top left to the bottom right of the cladogram (a seemingly trivial design factor), students scan from left to right and from top to bottom, which facilitates joining taxa to reflect the correct pattern of nesting. Thus, students were more successful in translating diagonal cladograms to the rectangular format when they were presented in the latter than the former orientation. Such diagrams, although they are commonly found in high school and college textbooks (Catley & Novick, 2008), appear to be poorly conceived and may reinforce evolutionary misconceptions. We wanted to determine whether the information extracted from such diagrams is in accordance with contemporary understanding of evolutionary theory. Our analyses documented persistent misconceptions that fall broadly into two categories: (a) Evolution as an anagenetic rather than a cladogenetic process and (b) evolution as a teleological (purpose-driven) process. Cladogenesis, the accepted means of speciation, is a process whereby one species splits into two when the population of a parent species is fragmented, and selection continues separately in each group driven by the pressures of each local environment. In a follow-up study conducted by Courtney Shade for her honors project, we compared students' responses to evolutionary relationship questions when they accompanied cladograms (in the rectangular and diagonal formats) versus other evolutionary diagrams often seen in textbooks. As predicted, we found that the textbook diagrams, which contained linear components, were more likely than the two cladogram formats to yield explanations of speciation as an anagenetic process.


In contrast, the branching cladogram formats yielded more appropriate interpretations in terms of levels of ancestry than did the textbook diagrams.
If the branches were rotated at the point indicated by the synapomorphy amniotic egg, the two mammals (manatee and elephant) would move to the middle of the diagram and the lizard would move to the far right location, without altering the pattern of connections among the taxa. If the cladogram were oriented vertically rather than horizontally, a similar rotation would move the mammals from the top to the middle and the lizard from the middle to the top. In two studies, we examined college and high school students' propensity to state that humans (versus honeybees) are the most highly evolved taxon when they occupied an end (far right or top) versus middle position in the cladogram (Phillips, Novick, & Catley, 2013). Both age groups were quite likely to incorrectly say that humans are the most highly evolved taxon of those depicted in the cladogram but highly unlikely to make the same claim about honeybees, even though those two taxa were similarly situated in their cladograms. This finding replicates earlier research on students' misconceptions about human evolution. From a diagram design perspective, the more interesting result is that for the cladogram that included humans, students were more likely to say that taxon is most highly evolved when it occupied an end rather than a middle position in the cladogram. Documenting students' tree-thinking skills based on naturally-occurring instruction in college and high school biology classes is a critical first step for developing new curricula to improve students' ability to engage in this important 21st century skill. Accordingly, a second major focus of our research program concerns students' ability to engage in tree thinking. In this study, students answered questions such as: (a) "What character was possessed by the most recent common ancestor of lizards and mammals?" [answer is amniotic egg], (b) "Which taxa did not evolve from an ancestor that had lungs?" [answer is lobsters, spiders, perch, and flounder], and (c) "Are lungfish more closely related to mammals or to flounder? What evidence supports your answer?" [answer is mammals because lungfish share a more recent common ancestor with mammals than they do with flounder]. Briefly, we found that students with a stronger background in biology did better than those with a weaker biology background on all of our core categories of tree-thinking questions. For the simplest questions -- identify characters (a) and identify taxa (b), for which students just had to read information off the cladograms, the difference between the two groups was larger for the diagonal format than for the rectangular format. For the more difficult relationship (c) and inference questions, the biology background difference was consistent across all other manipulations. In general, the stronger background students did better in terms of both accuracy and quality of supporting evidence cited.
Replicating the results of Novick and Catley (2007), this study also found poorer performance when the evolutionary relationships were depicted in the diagonal than the rectangular format. Except for the easiest question types, even stronger background students found the diagonal format more difficult to understand than the rectangular format. Several cognitive and perceptual factors were found to affect students' performance, including, for example, the Gestalt principle of good continuation and whether the question was worded affirmatively or negatively. Second, to inform our adaptation of the undergraduate curriculum for use with high school students, we collected data on tenth-graders' ability to engage in tree thinking (Catley, Phillips, & Novick, in press).
We have conducted three studies evaluating our novel tree-thinking curriculum for college students, which are described in the next several paragraphs.
A manuscript reporting the development of our college curriculum and associated assessment instrument, as well as the results of our implementation studies, is currently in preparation (Novick et al., 2013). Because of serious validity issues with the only published macroevolution assessment instrument (Novick & Catley, 2012), we developed our own tree-thinking assessment for our curriculum studies. In the spring of 2012, we conducted an initial test of a high school version of our curriculum in 10th grade biology classes in a rural high school in western North Carolina. A laboratory test of this instruction was conducted by Emily Schreiber for her honors project.
A Cohen's d of 1.42 for the core tree-thinking skills composite measure indicated a large overall effect of instruction.
Although there was no delay between completing the instructional booklet and taking the test, students were not allowed to refer back to the instructional booklet to answer the test questions. To ensure comparability of the student samples, we restricted this comparison to the results for just the stronger background students in the present study.
For two types of tree-thinking questions, our self-paced instructional booklet led to comparable performance as the lengthier classroom instruction. For two additional types of tree-thinking questions, our instructional booklet led to better performance. The enhanced tree-thinking instruction condition consisted of a revision of the self-paced instructional booklet, two days of lecture (taught by Kefyn), and a phylogenetics laboratory we wrote for the laboratory portion of the course.
The business-as-usual instruction condition consisted of the phylogenetics laboratory we wrote and whatever material on phylogenetics the instructor chose to cover in the lecture portion of the course.
Because students in the business-as-usual condition did not receive a heavy dose of phyogenetics in lecture, we judged it unwise to announce the posttest in advance. We expected those students would complain about being tested on material that might not have been covered.
Because students were prevented from studying for this test, their scores were lower than they otherwise would have been.
Nevertheless, it is possible to look for a difference between the two instructional conditions in the amount of improvement from pretest to posttest. Statistical analyses confirmed the superiority of our enhanced tree-thinking instruction over business-as-usual instruction: (a) Students who received our enhanced instruction had higher scores than did students who received business-as-usual instruction. The difference in the amount of improvement yielded a Cohen's d = 0.59, which represents a medium size effect for the increased effectiveness of our enhanced tree-thinking instruction relative to business-as-usual. The instruction, which occurred during the first four weeks of the semester, consisted of a further revision of the instructional booklet, additional days of instruction during the lecture portion of the class, a revision of the phylogenetics laboratory used in the introductory biology class (Study 2), additional laboratory and homework activities, instruction in how to interpret cladograms in the more difficult diagonal format, and field work.
The 17 students in this class across the two semesters combined completed our revised tree-thinking assessment before instruction began and then again a few weeks after midterm.
Most questions on the assessment, like all the questions on the assessments used in Studies 1 and 2, concerned evolutionary relationships depicted in the rectangular format. A smaller number of questions concerned evolutionary relationships depicted in the diagonal format so that we could gauge the effectiveness of our instruction concerning how to interpret hierarchical structure in that format.
We also computed separate composite tree-thinking measures for the comparable questions asked about cladograms in the rectangular and diagonal formats. Analysis of these data revealed that (a) students received significantly higher tree-thinking scores when the questions were asked about relationships depicted in the rectangular than the diagonal format, (b) students received significantly higher tree-thinking scores on the posttest than on the pretest, and (c) there was no interaction between cladogram format and time of test, indicating that our instruction in how to interpret the diagonal format did not reduce the decrement in tree-thinking skill associated with having to reason about relationships depicted in that format. In fact, the trend was for the improvement from pretest to posttest to be greater for rectangular than diagonal format questions.
In our manuscript (Novick et al., 2013), we also report more qualitative indicators of the positive effect of our tree-thinking instruction on students' learning. Reading phylogenetic trees: Effects of tree orientation and text processing on comprehension. Reasoning about evolutionary history: The effects of biology background on post-secondary students' knowledge of most recent common ancestry and homoplasy.



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25.08.2014, author: admin


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