5. W hy are biofilms important? Why is the prevention of biofi environment? 56.
ID: 199320 • Letter: 5
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5. W hy are biofilms important? Why is the prevention of biofi environment? 56. Why are bacterial 57. U capsules medically important? se the terms species, culture, clone, and strain in one sentence to describe growing methic resistant Staphylococcus aureus (MRSA). 58. Why wouldn't the definition of a viral species work for a bacterial species? 59. A patient with a heart pacemaker received antibiotic therapy for streptococcal bacterem in the blood). One month later, he was treated for recurrence of the bacteremia. weeks later, again with bacteremia, the physician recommended replacing the pacen When he returned six aker. Why did this cure his condition? 60. Could humans/eukaryotic cells exist on chemically defined media, at least under laboratory conditions? Explain your answer. 61. Give at least three reasons why a bacterial colony does not grow an infinite size, or at least fill the confines of the Petri plate. 62. W hy is it generally easier to determine the cause of pneumonia than it is to determine the cause of a wound infection (cutting yourself with a knife)? 63. What is the difference between the term bacillus and Bacillus? How would you be able to identify streptococci through a microscope? glycocalyx, pilli, flagella, fimbriae, and axial filaments. Give one reason how each structure would give the microorganism a survival advantage against the human immune system and or against antibiotics. 64. Describe the structure and function of each of the following: What determines the result of Gram Staining? Why is it important? Describe the bacterial cell wall from superficial to deep. 65.Explanation / Answer
55. Biofilms are formed when a group of microorganisms stick together or group together. Biofilms are naturally formed on surfaces of rocks, rivers etc. They help to shield the bacteria from harmful substances. The bacteria undergo a phenotypic change in biofilm. They are important in food chain of rivers and stream and can be grazed upon by aquatic invertebrates. They are important in nitrogen fixation or crop diseases.
Biofilms have an exopolysaccharide matrix that helps in adhesion and aggregation. This matrix prevents antibodies and phagocytes to adhere to the bacteria. Biofilms also increase resistance to antibiotics, as antibiotics may not be able to diffuse. Many bacteria can exist in a non-living state beneath the biofilm. Hence, this increases chances of antibiotic resistance. Cells on the surface of the biofilm can detach from the biofilm and infect the host.
Prevention of biofilms is important in health care set up. Nosocomial infections are common in healthcare environment. Biofilms on inserted medical devices act as a reservoir of protected bacteria. These films may persist even after removal of the medical device. Increased resistance to antibiotics will help spread of infections that are too difficult to treat.
56. Bacterial capsule are polysaccharide covering that is present outside the cell wall/membrane. They are virulence determinants as they are anti-phagocytic. They limit the ability of phagocytes to engulf the bacteria. Phagocytes cannot adhere and engulf bacteria due to the smooth nature and negative charge of the capsule.
Capsules allow pathogenic bacteria to cause disease. Bacterial capsules prevent direct access of lysosomal content with the bacterial cell. Hence, the bacteria cannot be killed by the phagocytes. They prevent complement-mediated bacterial cell lysis and protect anaerobes from oxygen toxicity. Capsule helps the bacteria in infection and to evade immune responses of the host.
57. Different strains of actively growing Methicillin Resistant Staphyloccous aureus (MRSA), a type of antibiotic resistant bacterial species, can be cultured on a media containing methicillin.
58. Viruses cannot grow and divide without a host cell. It utilizes host cell machinery to synthesize proteins and form new viruses. They lack the system for self production. Viruses are therefore classified as non-living. Bacteria, on the other hand cab self replicate and divide. Hence, they are classified as living and belong to one domain. Viruses do not belong on any of the kingdoms. Viruses are classified as non-living group of viruses depend on the nucleic acid composition and capsid structure. Hence, their definition cannot work for bacteria.
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