What would most likely occur if you drenched the bacterial smear in alcohol for 1 minute quizlet?
What would most likely occur if you drenched the bacterial smear in alcohol for 1 minute during a Gram stain? All purple stain would escape as the cell wall of both Gram-positive and Gram-negative bacteria would dissolve.
Can you see bacteria through a microscope?
Bacteria are too small to see without the aid of a microscope. While some eucaryotes, such as protozoa, algae and yeast, can be seen at magnifications of 200X-400X, most bacteria can only be seen with 1000X magnification. Even with a microscope, bacteria cannot be seen easily unless they are stained.
Which step in the Gram stain is most likely to cause poor results if done incorrectly?
The decolorization of the cells is the most “operator-dependent” step of the process and the one that is most likely to be performed incorrectly. Rinse with water to stop decolorization. Rinse the slide with a counterstain (safranin or carbol fuchsin) which stains all cells red.
What is the Micromorphology of Treponema pallidum?
Micromorphology: Tightly coiled (0.1-0.18 x 6-20 µm). Has 2-4 periplasmic flagella at each end of the cell. Generation time: 24-30 h.
How long will you wash the bacterial smear with alcohol?
5. Decolorize with 95% ethanol: let the alcohol run over surface of slide until no more crystal violet color comes out of the smear (time varies—no more than 5-10 seconds). 6. Rinse with water.
Why are bacterial samples stored in the fridge?
For strains that are used daily or weekly, cultures grown on agar slants or plates can be stored in a refrigerator assuming that precaution has been taken to avoid contamination. Cultures stored in stabs are more resistant to drying and contamination, but they will lose viability more quickly than frozen stocks.
What is 1000x magnification?
At 1000x magnification you will be able to see 0.180mm, or 180 microns.
Why is it important to know if a bacteria is Gram positive or negative?
The main benefit of a gram stain is that it helps your doctor learn if you have a bacterial infection, and it determines what type of bacteria are causing it. This can help your doctor determine an effective treatment plan.
What kills Treponema pallidum?
Penicillin, the first antibiotic developed, was the first known effective antibiotic for T. pallidum and remains the treatment of choice today (12, 30, 94). The maximally treponemicidal serum concentration of penicillin is 0.36 µg/ml which can kill the organism in 6 to 9 hours (27).
How does Treponema pallidum affect the body?
Treponema pallidum subsp pallidum, the most invasive of the pathogenic treponemes, produces highly destructive lesions in almost any tissue of the body, including the central nervous system. Treponema carateum is the least invasive and causes only cutaneous disease.
How do you measure zone of inhibition for pneumococcus?
Using a 6 mm, 5 µg disk, a zone of inhibition of 14 mm or greater indicates sensitivity and allows for presumptive identification of pneumococci ( Figure 5 ). Zones of inhibition should be measured from the top surface of the plate with the top removed. Use either calipers or a ruler with a handle attached for these measurements.
What did Gram observe while observing the lung tissues under the microscope?
While observing the lung tissues under the microscope, Gram noted that only some of the bacterial stains were being retained by the bacterial cells (1).
Which slides display only Gram negative bacteria?
This inference was made because slide 3 that contained E. coli and S. marcescens displayed only gram negative bacteria because the image viewed under the microscope was a pink color.
How do you test for optochin resistance in pneumococci?
In the case of an isolate completely resistant to optochin, the diameter of the disk (6 mm) should be recorded. A smaller zone of inhibition (< 14 mm) or no zone of inhibition indicates that the bile solubility test is required. It is important to remember that pneumococci are sometimes optochin-resistant.
