The following phenomenon is responsible for antibiotic resistance in bacteria due to slime production –
Correct Answer: Biofilm formation
Description: SLIME LAYER : many bacteria secrete a viscid material around the cell surface. when this is organised into a sharply defined structure as in pneumococcus it is known as capsule When it is a loose undemarcated secretion as in leuconostoc it is called slime layer. Capasule too thin to be seen under light microscope are called micro capsule. The slime is generally but not invariably ,polysaccharide or polypeptide in nature. some bacteria have both slime layer and capsule. Bacteria secreting large amount of slime produce mucoid growth on agar which is of stringy consistency when touched with loop. Slime have little affinity for basic dyes and is not visible in gram stained smears. Special capsule staining techniques are available usually employing copper salts as mordants. Capsules may be readily demonstrated by negative stainig in wet films with indian ink when they are seen as clear halos around the bacteria against a black background. Capsular material is antigenic and may be demonstrated by serological methods. When a suspension of a capsulated bacterium is mixed with its specific anticapsular serum and examined under microscope , the capsule become very prominent and appears to be swollen due to increase in its refractivity. The capsule swelling or quellung reaction was widely employed for the typing of pneumococci in the pre sulphonamide days when lobar pneumonia used to be treated with specific anticapsular sera. Capsule protect bacteria from deleterious agents such as lytic enzymes in found in nature. They also contribute to the virulence of pathogenic bacteria by inhibiting phagocytosis. Loss of capsule by mutation may render the bacterium avirulent. Repeated subcultures in vitro leads to the loss of capsule and also of virulence. REF:Ananthanarayan and Panicker's Textbook ofMicrobiology 8thEdition pg no:19
Category:
Microbiology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now