Mount Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Mount and links to relevant pages within the course.
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|Pneumococcal vaccine is particularly effective in children less than two years of age.||View Page|
Listeria monocytogenes is optimally motile at 25C; and is non-motile at 35-37C. Motility may be directly assessed by observing bacterial cells with a tumbling motion in a direct mount preparation. In soft motility agar, the identification can be made by observing for a thin, umbrella-like lateral extension of growth from the stab line (noted by arrows in the image).
|What test(s) which may be performed to establish a presumptive differential identification between group B streptococci and L. monocytogenes?||View Page|
|The Iodine prep method is used to detect which of the following protozoan stages:||View Page|
|Treatment of CDI/CDAD|
The first step in treating patients with CDAD is to discontinue the causative agent wherever possible. The choice for initial antibiotic therapy depends on the severity of disease. Oral vancomycin or metronidazole remain the mainstays of therapy for C. difficile infection, with vancomycin reserved for patients with more severe disease and/or those who have not responded to metronidazole. Metronidazole is currently favored in guidelines from the CDC on the basis of cost and concern that oral vancomycin promotes colonization with vancomycin-resistant Enterococcus. Oral fluids (water and electrolytes) may be necessary to counteract fluid loss as a result of excessive diarrhea, which can quickly lead to dehydration. Patients with fulminant disease and toxic megacolon may require colectomy. Recurrence of C. difficile infection (CDI) is becoming an increasing problem. Most recurrences happen 7 - 14 days after completion of therapy, suggesting relapse rather than re-infection. If a patient develops a second episode of CDI following initial successful treatment, it is recommended that if possible, the same drug be used to treat the second episode. Contributing factors to recurrent CDI include: Continuing exposure to organisms either through re-infection (via contaminated environment or poor hand hygiene) or an endogenous source, such as C. difficile spores in GI tract. An inability to mount an adequate anti-Toxin A IgM and/or IgG antibody response (i.e., poor host immune response); a likely reason why CDI affects an increasingly elderly population. Unfortunately a vicious cycle can arise whereby the initial treatment prescribed, vancomycin or metronidazole, significally disrupts normal colonic flora reducing colonization resistance and leaving the patient vulnerable to the next recurrent episode.Other treatments including the use of probiotics or anion-exchange resins to absorb toxins, may work in some cases but none work in every case.The goal of all treatment is to reestablish normal colonic flora so as to control C. difficile (over)growth.
|An Aspergillus species was recovered from a sputum specimen of a patient with X-ray evidence of fungal pneumonia. Microscopic examination did not permit a species identification. A small amount of vegetative mycelium was removed and a direct mount prepared. The features indicated by the red arrows in this image are associated with which Aspergillus species?||View Page|
|A dull white fungus, turning mouse gray on maturity, was recovered from material aspirated from a bone cyst in the upper femur. Based on the microscopic appearance as seen in a lactophenol blue mount of a portion of the colony, the most likely identification is:||View Page|
|The hyaline saprobic fungus that has microscopic features similar to the mold form of Coccidioides immitis is:||View Page|
|The dematiaceous conidium illustrated in this photomicrograph was obtained from a tiny portion of dark colony that grew to maturity in six days. Spores incubated in a saline mount for four hours developed germ tubes from both terminal cells. The features observed confirm the identification of:||View Page|
|The colonies shown in the upper image were obtained on blood agar from a sputum specimen after 10 days incubation at 30°C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The diagnosis is:||View Page|
|The growth of the colonies shown in the upper image was obtained on blood agar from a sputum specimen after 8 days of incubation at 30°C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The diagnosis is:||View Page|
|The colonies shown in the upper image, obtained from a biopsy of an ulcerating skin lesion of the arm, are growing on agar slants of Sabouraud's dextrose agar. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony growing in the left slant. The diagnosis is:||View Page|
|One of the characteristics common to the dimorphic molds is the ability to convert the mold forms to the yeast forms by incubating subcultures in enriched media at 35°-37°C. The upper image illustrates a subculture of a mold colony suspected of being a dimorphic fungus inoculated to the surface of blood agar and incubated for 3 days at 37°C. Note that the colonies have a prickly appearance, suggesting an intermediate stage of conversion. The lower image is a lactophenol blue mount of a portion of one of the prickly colonies. This fungus can be identified as:||View Page|
|This image illustrates a lactophenol blue mount of a mold recovered after 7 days incubation of brain heart infusion broth. The large macroconidia suggests the mold form of Histoplasma capsulatum. However, there is the possibility that this mold represents its saprophytic counterpart, which is:||View Page|
|This image illustrates a lactophenol blue mount prepared from a mold recovered after 7 days incubation on brain heart infusion broth. The individual microconidia, each borne by a delicate conidiophore, suggests the mold form of Blastomyces dermatitidis. However, there is the possibility that this mold represents its saprophytic counterpart, which is called:||View Page|
|The colonies growing on the surface of this brain-heart infusion with blood agar plate were "converted" from a mold colony suspected of being Histoplasma capsulatum by incubating a subculture at 37°C for 5 days. The yeast forms that must be identified in mounts made from one of these colonies to confirm the identification are:||View Page|
|The growth of the yeast-like colonies shown in the upper image was obtained on blood agar from a skin culture only in the area overlaid by virgin olive oil. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The disease associated with this fungus is:||View Page|
|How should the sperm motility be categorized in this microscopic field of a semen sample viewed at 400X magnification?This video is used with permission of Kokopelli Technologies, LLC. ||View Page|
|A semen specimen was collected three hours before it was brought to the laboratory for examination. What course of action should be taken?||View Page|
The following is a list of materials needed for semen analysis. Laboratories will differ slightly in the equipment used. Use of this equipment will be described further in the later pages of this course. Materials needed include:graduated test tube or serological pipets with safety bulb to measure volumepH paper in neutral to basic range (e.g. 7.2-8.8)counting chamber and/or automated counting machineglass slides and coverslips for wet mount if motility and sperm count are to be assessed separatelyhand counterif dilution is donediluting fluid calibrated automatic pipetspositive pressure pipets and glass boreslight microscope with phase contrast objectives for sperm count and bright field objectives for morphology assessmentglass slides and fixative for morphology slidesset-up for performing Papanicolaou or other morphology stainingReference materials, such as the most current WHO laboratory manual for the examination and processing of human semen, a publication of the World Health Organization.
|Sperm Counting Methods|
Sperm can be counted either manually or by automated methods. Although automated counting has some advantages for assessment of motility parameters, manual counting is still performed by most laboratories. There are several manual counting methods available for semen. These include: Improved Neubauer hemocytometerMakler chamberCellVu (Millennium Sciences, Inc)MicroCell (Conception Technologies) The Makler, CellVu, and MicroCell methods have the advantage of requiring no dilution of the semen. Since semen is viscous, accurate dilution can be problematic. These methods also allow counting of motile and non-motile sperm at the same time and thus avoid the need for separate assessment via wet mount. Each laboratory should determine the best most reproducible method for their own situation, equipment, and expertise.
|Other Counting Chambers|
Some professionals believe that sperm counts done by hemocytometer are not accurate because of the need to dilute the viscous semen prior to counting. There are several other counting methods available to assess sperm concentration. The advantages of the following methods are: The specimen does not have to be diluted Motile and non-motile sperm can both be counted avoiding the need for wet mount evaluation of motile cells. Note that counting moving sperm can be difficult and takes significant practice to avoid error. Makler (Zygotek Systems, Inc.). An undiluted sample is placed on the chamber and covered with the coverglass. Ten squares on the grid contain 0.000001ml. CellVu (Millennium Sciences, Inc). Two sides of a special slide are loaded with a drop of undiluted semen. Coverslips with special grids are placed on top of the sperm according to manufacturer's directions. Sperm on both sides are counted.MicroCell (Conception Technologies) has two chambers on a single, disposable slide. A special eyepiece with a grid is needed for counting.
|Wet Mount Assessment of Sperm Motility|
Two wet mount slides should be prepared and examined for sperm motility. Evaluate at least five fields and/or a minimum of 200 spermatozoa on each replicate. The high power objective (400X magnification) should be used. For very low counts, increased numbers of fields may have to be examined and the total number of sperm may be less than 100. Calculate the average percentage of each category on each slide and then compare the differences between the two percentages for the most frequent motility grade that was reported (progressive, non-progressive, or immotile). The table below, provided by WHO 5th edition, may be used to determine if the counts obtained from the replicate slides are sufficiently in agreement. If they are not, two additional replicates should be made from the original specimen and the motility assessment should be repeated. Acceptable Differences Between Two Percentages for a Given AverageDetermined from Replicate Counts of 200 Spermatozoa (total 400 counted) Average (%)Acceptable Difference0112233 - 445 - 758 - 11612 - 16717 - 23824 - 34935 - 651066 - 76977 - 83884 - 88789 - 92693 - 95596 - 9749839921001
WHO 5th edition recommends reporting these categories of movement:Progressive motility: Spermatozoa are moving actively (not necessarily rapidly), either linearly or in a large circle. Several examples of progressive motility can be seen in the attached video.Non-progressive motility: There is an absence of progression, e.g., swimming in small circles; the head is barely moving as the result of the flagellar movements; only the flagellar movement is noted. An example of non-progressive motility can be viewed on the following page.Immotility: Total absence of movement Complete the assessment of progressive motility in the area of observation, followed by non-progressive motility, and finally immotility.The lower reference limit for progressive motility is 32%. The lower reference limit for total motility (progressive + non-progressive) is 40 %. This video and the video on the following page are used with permission of Kokopelli Technologies, LLC.
|Trichomonas versus White Cells|
When the urine cools or when the wet mount begins to dry, Trichomonas begins to lose its characteristic motility and may easily be misinterpreted as white cell or epithelial cell.