Which of the following is a Tetracycline?

Doxycycline is indeed a tetracycline antibiotic. This class of antibiotics, which also includes other members like tetracycline itself, is characterized by a particular four-ring structure in their chemical configuration. Tetracyclines are known for their broad spectrum of activity against various bacteria and are commonly used to treat a range of infections, including respiratory infections, acne, and certain sexually transmitted infections.

The effectiveness of doxycycline is attributed to its ability to inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit. This mechanism of action makes tetracyclines a valuable option in treating infections caused by both gram-positive and gram-negative bacteria, as well as atypical organisms.

Other antibiotics listed—amikacin, gentamicin, and streptomycin—belong to different classes such as aminoglycosides, which have distinct characteristics and mechanisms of action, targeting different types of bacteria and being used for different clinical settings.