Clindamycin is a lincosamide antibiotic medication used for the treatment of a number of bacterial infections, including osteomyelitis (bone) or joint infections, pelvic inflammatory disease, strep throat, pneumonia, acute otitis media (middle ear infections), and endocarditis.[5] It can also be used to treat acne, [5][6] and some cases of methicillin-resistant Staphylococcus aureus (MRSA).[7] In combination with quinine, it can be used to treat malaria.[5][6] It is available by mouth, by injection into a vein, and as a cream or a gel to be applied to the skin or in the vagina.[4][5][6][8][9] Common side effects include nausea and vomiting, diarrhea, skin rashes, and pain at the site of injection.[5] It increases the risk of hospital-acquired Clostridium difficile colitis about fourfold and thus is only recommended for use when other antibiotics are not appropriate.[10][5] It appears to be generally safe in pregnancy.[5] It is of the lincosamide class and works by blocking bacteria from making protein.[5] Clindamycin was first made in 1966 from lincomycin.[11][12] It is on the World Health Organization's List of Essential Medicines.[13] It is available as a generic medication.[14][15] In 2021, it was the 118th most commonly prescribed medication in the United States, with more than 5 million prescriptions.lindamycin is used primarily to treat anaerobic infections caused by susceptible anaerobic bacteria, including dental infections, [18] and infections of the respiratory tract, skin, and soft tissue, and peritonitis.[19] In people with hypersensitivity to penicillins, clindamycin may be used to treat infections caused by susceptible aerobic bacteria, as well. It is also used to treat bone and joint infections, particularly those caused by Staphylococcus aureus.[19][20] Topical application of clindamycin phosphate can be used to treat mild to moderate acne.[21][22]When testing a gram-positive culture for sensitivity to clindamycin, it is common to perform a "D-test" to determine if there is a sub-population of bacteria present with the phenotype known as iMLSB. This phenotype of bacteria are resistant to the macrolide-lincosamide-streptogramin B group of antibiotics, however, the resistance mechanism is only induced by the presence of 14-membered ring macrolides, such as erythromycin. During a D-test, bacteria of the iMLSB phenotype demonstrate in vitro erythromycin-induced in vitro resistance to clindamycin. This is because of the activity of the macrolide-inducible plasmid-encoded erm gene.[30]