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Macrolides and KetolidesThe macrolides (Azithromycin (Zithromax) and clarithromycin (Biaxin) inhibit bacterial protein synthesis and are effective in treating gram-positive and “gram-negative aerobes and
7atypical organisms (chlamydia, mycoplasma, legionella, rickettsia, mycobacteria, and spirochetes)” (Graziani, 2018). Even though Erythromycin (E-Mycin) is the original macrolide its use is limited due to GI effects and hepatoxicity. Telithromycin (Ketek) belongs to the ketolide class of antimicrobials and is related to the macrolide class, however the reports of hepatoxicity, visual disturbances and myasthenia gravis makes it (Graziani, 2018). The half-life of macrolides varicose for two hours (erythromycin) to four/five hours (clarithromycin) and up to 50 to 60 hours for azithromycin and are hepatically cleared (Arcangelo et al., 2017). Due to their broad spectrum of coverage, the macrolides are used to treat the infections of respiratory tract, skin, soft tissue, sexually transmitted diseases, “HIV-related Mycobacterium avium–Mycobacterium intracellulare complex infection, and other infections caused by atypical organisms such as chlamydia, rickettsiae, and legionella” (Arcangelo et al., 2017, page 121). Hepatoxicity, GI side effects, Stevens-Johnson syndrome, drug reaction with eosinophilia and systemic symptoms (DRESS), pseudomembranous colitis and QT prolongation have been associated with macrolides and the clinician should assess the patient’s history for torsades de pointes or any medication that prolong the QT interval (Graziani, 2018). In patients with below creatinine clearance of less then 30 mL/min, the dose of clarithromycin should be reduced in half(Graziani, 2018). Azithromycin is a pregnancy class B and clarithromycin with telithromycin are a pregnancy class C drugs (Graziani, 2018).Macrolides are increasingly facing resistance, however, despite the high rates of macrolide-resistant S. pneumoniae in community-acquired pneumonia (CAP), the macrolides arestill useful as a combined antibiotic, due to their immunomodulatory, anti-inflammatory and reduction of tumor necrosis factor-alpha effects (Graziani, 2018).Aminoglycosides
8The aminoglycoside class covers a broad spectrum of aerobic gram-negative (Escherichiacoli, Klebsiella species, Proteus mirabilis, Enterobacter species, Acinetobacter species, and P. aeruginosa) and gram-positive organisms (particularly Staphylococcus, Enterococcus, and Streptococcus), Francisella tularensis and Mycobacterium tuberculosis but are inefficient in anaerobic bacteria (Drew, 2018). This class includes the following antibiotics: gentamicin, tobramycin, amikacin, plazomicin, streptomycin, neomycin, and paromomycin (Drew, 2018). The mechanism of action is disruption of mRNA translational accuracy by disrupting intracellular magnesium and calcium bridges (Drew, 2018). Despite the fact that aminoglycosides have a good resistance record, their clinical use is limited due to their toxicity and needs for drug serum concentration monitoring to avoid nephrotoxicity, ototoxicity and neuromuscular blockade (Drew, 2018). The administration of calcium gluconate usually reverses