Correct Option: A

In the past 60 years, antibiotics have been critical in the fight against infectious disease caused by bacteria and other microbes. In 1946, penicillin became generally available for treatment of bacterial infections, especially those caused by staphylococci and streptococci. Initially, the antibiotic was effective against all sorts of infections caused by these two Gram-positive bacteria. Penicillin had unbelievable ability to kill these bacterial pathogens without harming the host that harbored them. It is important to note that a significant fraction of all human infections are caused by these two bacteria (i.e., strep throat, pneumonia, scarlet fever, septicemia, skin infections, wound infections, etc.). In the late 1940s and early 1950s, new antibiotics were introduced, including streptomycin, chloramphenicol and tetracycline, and the age of antibiotic chemotherapy came into full being. These antibiotics were effective against the full array of bacterial pathogens including Gram-positive and Gram-negative bacteria, intracellular parasites, and the tuberculosis bacillus. Synthetic antimicrobial agents such as the “sulfa drugs” (sulfonamides) and anti-tuberculosis drugs, such as para aminosalicylic acid (PAS) and isoniazid (INH), were also brought into wider usage. At present, tuberculosis treatment does not involve the usage of penicillin. The drugs used in the tratment of tuberculosis are ethambutol, isoniazid, rifampicin, etc.