The patient in this vignette presents with poor balance and visual disturbances during head turning, which is suggestive of vestibulopathy. Aminoglycoside antibiotics are used to treat gram-negative infections and are vestibulotoxic and ototoxic.
Intravenous aminoglycosides such as gentamicin, amikacin, and tobramycin are bactericidal antibiotics that are used to treat serious gram-negative infections. Gentamicin is one of the first-line agents used to treat acute pyelonephritis in the case of fluoroquinolone resistance or allergies. Aminoglycosides are associated with nephrotoxicity, neuromuscular blockade, and ototoxicity. Aminoglycoside-mediated ototoxicity often presents with predominantly vestibular symptoms such as imbalance, visual disturbances that are worse in the dark and occur only during head turning (oscillopsia), and nystagmus. Aminoglycosides function by irreversibly inhibiting the 30S ribosomal subunit, thereby blocking protein synthesis.
Answer 2: Multiple antibiotics inhibit the 50S ribosomal subunit. These include macrolides, clindamycin, linezolid, and chloramphenicol.
Answer 3: Sulfonamides are bacteriostatic antibiotics that block bacterial DNA formation by inhibiting dihydropteroate synthase in the folate synthesis pathway. Hypersensitivity reactions to sulfa drugs are among the most common adverse effects. Severe manifestations of these reactions include Stevens-Johnson syndrome, toxic epidermal necrolysis, and hemolytic anemia.
Answer 4: Beta-lactam antibiotics are a broad group of antibiotics including penicillins, cephalosporins, carbapenems, and monobactams. Beta-lactams inhibit the enzyme transpeptidase which normally functions to cross-link peptides in bacterial cell walls.
Answer 5: Fluoroquinolones are bactericidal antibiotics including levofloxacin, ciprofloxacin, and moxifloxacin. They inhibit DNA gyrase (prokaryotic topoisomerase II), which normally functions to relieve strain while DNA is being unwound by helicase. Inhibition of DNA gyrase leads to DNA breakage. Toxicities of fluoroquinolones include GI upset, tendon rupture, and cartilage damage.
Aminoglycosides are bactericidal antibiotics that inhibit the 30S bacterial ribosomal subunit, thereby causing irreversible loss of protein synthesis. Toxicities include nephrotoxicity, ototoxicity, and neuromuscular blockade.