Antibiotics are defined as a medicine, such as penicillin, that inhibits the growth of or destroys microorganisms. Antibiotic drugs such as amoxicillin, doxycycline, cephalexin, ciprofloxacin, clindamycin, metronidazole, azithromycin, and levofloxacin are used to kill microorganisms and cure bacterial infections. Classifications for antibiotics are penicillins, tetracyclines, cephalosporins, quinolones, lincomycins, macrolides, sulfonamides, glycopeptides, aminoglycosides, and carbapenems. According to Drugs.com, most antibiotics fall into their individual antibiotic classes. An antibiotic class is a grouping of different drugs that have similar chemical and pharmacologic properties. Their chemical structures may look comparable, and drugs within the same class may kill the same or related bacteria. The penicillin class contains five groups of antibiotics: aminopenicillins, antipseudomonal penicillins, beta-lactamase inhibitors, natural penicillins, and the penicillinase resistant penicillins. Tetracyclines are broad-spectrum against many bacteria and treat conditions such as acne, urinary tract infections or a UTI, intestinal tract infections, eye infections, sexually transmitted diseases, periodontitis, or gum disease, and other bacterial infections. There are five generations of cephalosporins, with increasing expanded coverage to include gram-negative infections. Cephalosporins treat many infections, including strep throat, ear infections, urinary tract infections, skin infections, and meningitis. The fifth generation cephalosporin ceftaroline is active against methicillin-resistant Staphylococcus aureus. The quinolones, also known as the fluoroquinolones, are a synthetic, bactericidal antibacterial class with a broad-spectrum of activity. The quinolones can be used for difficult-to-treat urinary tract infections when other options are being effective, hospital-acquired pneumonia, bacterial prostatitis, and even anthrax or plague. The FDA issued a strong warning about this class in 2016. This class has activity against gram-positive aerobes and anaerobes, as well as some gram-negative anaerobes. The lincomycin derivatives may be used to treat serious infections like pelvic inflammatory disease, intra-abdominal infections, lower respiratory tract infections, and bone and joint infections. Members of this class include clindamycin and lincomycin. The macrolides can be used to treat community-acquired pneumonia, pertussis, or for uncomplicated skin infections, among other susceptible infections. Ketolides are a newer generation of antibiotic developed to overcome macrolide bacterial resistance. Members of this class are azithromycin, clarithromycin, and erythromycin. Sulfonamides are effective against some gram-positive and many gram-negative bacteria, but resistance is widespread. Common uses for sulfonamides include UTIs, treatment or prevention of pneumocystis pneumonia, or ear infections. Members of this class include sulfamethoxazole-trimethoprim, sulfasalazine, and sulfisoxazole. Glycopeptide antibiotics, members of this group may be used for treating methicillin-resistant staphylococcus aureus infections, complicated skin infections, C. difficile-associated diarrhea, and enterococcal infections such as endocarditis which are resistant to beta-lactams and other antibiotics. Members of this class include dalbavancin, oritavancin, telavancin, and vancomycin. Aminoglycosides inhibit bacterial synthesis by binding to the 30S ribosome and act rapidly as bactericidal antibiotics. These drugs are usually given intravenously. Members of this class include gentamicin, tobramycin, and amikacin. Carbapenems, these injectable beta-lactam antibiotics have a wide spectrum of bacteria-killing power and may be used for moderate to life-threatening bacterial infections like stomach infections, pneumonias, kidney infections, multidrug-resistant hospital-acquired infections and many other types of serious bacterial illnesses. Members of this class include imipenem, meropenem, doripenem, and ertapenem.