Bacteriology - Mycobacteria Quiz

Mycobacteria can be cultured from a variety of clinical specimens, with respiratory specimens being the most common. This is because mycobacteria, such as Mycobacterium tuberculosis, primarily infect the respiratory system and cause diseases like tuberculosis. Therefore, respiratory specimens, such as sputum or bronchoalveolar lavage fluid, are commonly used for culturing mycobacteria in order to diagnose and monitor respiratory infections caused by these bacteria.

The use of a biological safety cabinet is essential; proper use of this cabinet will protect the technologist from aerosols created during specimen and culture handling

The cell wall is primarily composed of lipids, such as phospholipids and glycolipids, which form a lipid bilayer. These lipids provide structural support and help maintain the integrity of the cell wall. Additionally, lipids play a role in regulating the permeability of the cell wall, controlling the movement of substances in and out of the cell. Therefore, the cell wall has a high lipid content.

The Mycobacteria lab should be separated from the rest of the microbacteriology lab to prevent cross-contamination and ensure the accuracy of test results. Mycobacteria are a specific group of bacteria that can cause serious diseases such as tuberculosis, leprosy, and other infections. By separating the Mycobacteria lab, it reduces the risk of these bacteria spreading to other areas of the microbacteriology lab and potentially infecting other samples or individuals. This separation helps maintain a controlled environment and ensures the safety of laboratory staff and the integrity of the testing process.

Mycobacteria tend to grow slowly compared to other pathogenic bacteria. This slower growth rate is a characteristic feature of mycobacteria, which distinguishes them from other bacteria. This slow growth can be attributed to their unique cell wall structure, which makes them more resistant to environmental conditions and antimicrobial agents. Additionally, their slow growth rate contributes to the chronic nature of mycobacterial infections, as it takes longer for the bacteria to multiply and cause disease symptoms.

Mycobacteria are classified as thin, straight or slightly curved rods. This means that their shape is elongated and can have a slight bend or curve. The term "thin" refers to their width, indicating that they are not wide or bulky in shape. This classification helps to differentiate mycobacteria from other types of bacteria that may have different shapes and characteristics.

Mycobacteria are known to resist decolorization with acid alcohol. This resistance is due to the high lipid content in their cell walls, specifically mycolic acids. These mycolic acids make the cell walls hydrophobic and prevent the acid alcohol from penetrating and decolorizing the bacteria during the staining process. As a result, mycobacteria retain the primary stain (usually a red dye such as carbol fuchsin) and appear as red-colored bacilli under a microscope. This characteristic is used in the acid-fast staining technique, which is commonly used to identify and diagnose mycobacterial infections such as tuberculosis.

Mycobacteria are strictly aerobic, meaning they require oxygen to survive and grow. They cannot survive in the absence of oxygen. This is an important characteristic of mycobacteria and distinguishes them from other types of bacteria that can survive in anaerobic conditions.

They are nonmotile and do not produce spores.

M.leprae is the bacterium that causes leprosy. It is an obligate intracellular pathogen, which means it can only grow and survive inside human cells. It cannot be cultured or grown on artificial media in a laboratory setting. This makes it difficult to study and diagnose leprosy. Therefore, the statement that M.leprae will not grow on artificial media is true.

UV light kills bacteria so the biological safety cabinet, after cleaning with disinfectant, should have the light left on overnight

Most rapidly growing species of mycobacteria grow at temperatures between 20 and 40 degrees Celsius. This temperature range provides optimal conditions for their growth and metabolism. Below 20 degrees Celsius, the growth rate of these bacteria slows down, while above 40 degrees Celsius, their growth may be inhibited or completely stopped. Therefore, the temperature range of 20-40 degrees Celsius is the most suitable for the rapid growth of mycobacteria.

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Typically, three specimens of sputum are needed to make a diagnosis. This is because multiple samples increase the chances of detecting any infectious organisms or abnormalities present in the sputum. By analyzing three specimens, healthcare professionals can ensure a more accurate diagnosis and provide appropriate treatment.

When larger volumes of specimens are used, it increases the chances of detecting mycobacteria in the sample. This is because larger volumes provide more material for testing, increasing the likelihood of finding the bacteria. Therefore, larger volumes of specimens improve the recovery of mycobacteria.

Delays in processing may lead to false negative culture due to increased bacterial contamination

AF smears are not done due to the low numbers of organisms present

Areas where specimens and cultures are processed should have negative air pressure. This is because negative air pressure helps to prevent the spread of airborne contaminants. It works by creating a pressure difference between the contaminated area and the surrounding environment, causing air to flow into the area rather than out of it. This helps to ensure that any potentially harmful particles or microorganisms are contained within the processing area and do not escape into other parts of the facility.

Swabs are not typically used for collecting sputum specimens. Sputum specimens are usually collected by asking the patient to cough deeply and produce a sample directly into a sterile container. Swabs are more commonly used for collecting samples from surfaces or for obtaining specimens from the throat, nose, or other areas. Therefore, the statement that swabs can be used for sputum specimens is false.

No AF smear is performed due to fewer organisms present and the potential for contamination

Most rapidly growing species of mycobacteria will grow in less than 7 days.

The correct answer is 2-6 weeks. This is because most mycobacteria associated with disease have a slow growth rate and require a longer incubation period to form visible colonies. Therefore, it typically takes 2-6 weeks for these mycobacteria to grow and be detected in laboratory cultures.

If immediate transport is not possible for Mycobacteria specimens, refrigerating the specimens is the correct course of action. Refrigeration helps to slow down the growth of the bacteria and preserve the integrity of the specimens until they can be transported. This prevents any potential degradation or contamination of the specimens that could occur if they were left out at room temperature or stored in inappropriate conditions. Placing the specimens in an anaerobic jar or storing them in an incubator at 37 degrees Celsius would not be suitable for preserving Mycobacteria specimens.

The correct answer is 5-10 ml. This volume of sputum should be sent for analysis.

Urine is commonly used to diagnose Renal TB, and the first morning midstream specimen is the preferred sample. The minimum volume required for this specimen is 15 ml. This is because a larger volume of urine allows for a more accurate analysis and detection of any abnormalities or infections, such as Renal TB. A smaller volume may not provide enough material for a thorough examination, potentially leading to false-negative results. Therefore, a minimum volume of 15 ml is necessary for an effective diagnosis.

Gastric Aspirates are used primarily by children