Antibiotics and Immunity

Teichoic acid is a characteristic component of the cell wall of Gram-positive bacteria, providing structural support and helping in ion regulation.

Gram-positive bacteria are stained dark blue or violet by Gram staining. This is in contrast to gram-negative bacteria, which take up the counterstain and appear red or pink. 

When treated with crystal violet and subsequently with iodine, some bacteria remain colorless and these are called gram +ve bacteria.

Pyrogens can be the so called endotoxins or lipopolysaccharides, cell wall components of Gram negative bacteria such as E. coli, Salmonella or Bordetella, but also of the cell walls from Gram positive bacteria, e.g., so called lipoteichoic acids (LTA). When bacteria or viruses invade the body and cause tissue injury, one of the immune systems responses is to produce pyrogens. These chemicals are carried by the blood to the brain, where they disturb the functioning of the hypothalamus, the part of the brain, that regulates body temperature.

Gram - negative bacteria display the following characteristics: outer membrane containing lipopolysaccharide (which consists of lipid A, core polysaccharide, and O antigen) in its outer leaflet and phospholipids in the inner leaflet; porins exist in the outer membrane, which act like pores for particular molecules; lipoproteins are attached to the polysaccharide membrane.

Gram positive cells are characterized by presence of single thick layer of cell wall which is made up of peptidogycan, teichoic acid and lipoteichoic acid. Teichoic acid is acidic polymer of ribitol phosphate /glycerol phosphate and is covalently linked to peptidoglycan layer. Acetic acid is organic compound and is the main component of vinegar. Glutamic acid is one of the 20 standard amino acids and also serves as neurotransmitter. Malic acid is organic compound and serves as important intermediate in number of biochemical pathways; Kreb cycle and Glyoxalate cycle, etc. Thus, the correct answer is option B.

Taeniasis is an infection by the tapeworm, Taenia solium. It is caused by eating undercooked pork or contaminated food that contains tapeworm eggs or larvae which grow in the intestines when eaten. Praziquantel is the medication used to treat taeniasis because it is an antiworm medicine which prevents the growth and multiplication of worms inside the body. It increases the permeability of the membrane to calcium ions which induces contraction of the parasites, resulting in paralysis in the contracted state.

The antibiotics are substances produced by the natural metabolic processes of spore forming aerobic bacteria and fungi as their natural defense against other microorganisms. Among bacteria and fungi, bacterial genera outnumber the fungal genera in production of antibiotics. The highest numbers of antibiotics are derived from bacterial genera Streptomyces and Bacillus and fungal genera Penicillium and Cephalosporium. This makes option A correct. Viruses do not perform any metabolic activity outside the host and hence, do not produce any antimicrobial agents. Angiosperms are most developed flowering plants that have number of adaptation to make them less susceptible for competition for food and space; they do not produce antibiotics. Thus, the correct answer is option is A.

Antibiotics serve as metabolic analogs and control the microbial growth by competing with the necessary enzyme to halt the growth of bacterial cells. Antibiotics occupy the enzyme’s active site thereby blocking the binding of its natural substrate to the enzyme. This puts the whole pathway to halt. Inhibition of enzyme activity by a metabolic analog of the natural substrate is termed as competitive inhibition.

The antibiotics are substances produced by the natural metabolic processes of spore forming aerobic bacteria and fungi as their natural defence against other microorganisms. Immune host is the one which has acquired immunity against certain antigen by administration of antibiotics. It produces antibodies, not the antibiotics which makes option A incorrect. Commercial production of antibiotics by parasitic fungi needs their culture in live host cells which is a tedious and expensive process; Option B is incorrect. Saprophytic bacteria feed on dead and decaying organic matter and therefore, can easily be cultured on synthetic medium; option C is correct. Since, viruses are metabolically inactive outside the host cell and depend on host for their own nutritional requirements, they do not produce antibodies. Option D is incorrect. Thus, the correct answer is option C. 

Toxin is the harmful substance secreted by bacteria. It affects the immune system of the host. It causes infection and disease in the host by damaging the tissues. Paratope is an antigen-binding site present on the antibody. 

The antibiotics are the chemical substances produced by the natural metabolic processes of bacteria and fungi as their natural defense against other microorganisms. Penicillin is an antibiotic that target the peptide cross-links in the peptidoglycan and disrupt the cell wall integrity. Exposure of penicillin to bacteria stops the cell wall synthesis by inhibition of formation of peptide linkage and bacteria become protoplast (a fragile cell bounded only by a membrane) which is highly susceptible to lysis.  Thus, the correct answer is option C.