Macrolides
Macrolides are agents that bind to the 50S ribosomal subunit of susceptible organisms, resulting in inhibition of protein synthesis. Examples such as azithromycin, erythromycin, and clarithromycin are all reasonable alternatives in patients who are allergic to penicillins.
Azithromycin (Zithromax, Zmax)
Azithromycin acts by binding to the 50S ribosomal subunit of susceptible microorganisms and blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Nucleic acid synthesis is not affected. It is used to treat mild to moderate microbial infections.
Erythromycin (Erythrocin, E.E.S., Ery-Tab, EryPed)
Erythromycin inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. It is used for the treatment of staphylococcal (not MRSA) and streptococcal infections.
Clarithromycin (Biaxin, Biaxin XL)
Clarithromycin is a semisynthetic macrolide antibiotic that reversibly binds to the P site of the 50S ribosomal subunit of susceptible organisms and may inhibit RNA-dependent protein synthesis by stimulating dissociation of peptidyl t-RNA from ribosomes, causing bacterial growth inhibition. It has a similar susceptibility profile to erythromycin but has fewer adverse effects.
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Mild cellulitis with a fine lacelike pattern of erythema. This lesion was only slightly warm and caused minimal pain, which is typical for the initial presentation of mild cellulitis.
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Swelling seen in cellulitis involving the hand. In a situation with hand cellulitis, always rule out deep infection by imaging studies or by obtaining surgical consultation.
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Severe cellulitis of the leg in a woman aged 80 years. The cellulitis developed beneath a cast and was painful and warm to the touch. Significant erythema is evident. The margins are irregular but not raised. An ulcerated area is visible in the center of the photograph.
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Burns complicated by cellulitis. The larger lesion is a second-degree burn (left), and the smaller lesion is a first-degree burn (right), each with an expanding zone of erythema consistent with cellulitis.
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Cellulitis due to documented Vibrio vulnificus infection. (Image courtesy of Kepler Davis.)
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A case of cellulitis without associated purulence in an infant. Note the presence of lymphedema, a risk factor for cellulitis.(Photo courtesy of Amy Williams.)
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Patient with cellulitis of the left ankle. This cellulitis was caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). (Photo courtesy of Texas Dept. of Public Health.)
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Abscess and associated cellulitis caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). (Photo courtesy of Texas Dept. of Public Health.)
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Guidelines for the management of patients who require hospitalization for cellulitis or cutaneous abscess. AFB = acid-fast bacilli; BID = twice daily; CRP = C reactive protein; CT = computed tomography scanning; DS = double strength; DM = diabetes mellitus; ESR = erythrocyte sedimentation rate; ESRD = end-stage renal disease; HIV = human immunodeficiency virus; ICU = intensive care unit; I&D = incision and drainage; ID = infectious disease; IDU = injection drug user; IV = intravenous; LRINEC = Laboratory Risk Indicator for Necrotizing Fasciitis; MRI = magnetic resonance imaging; MSRA = methicillin-resistant Staphylococcus aureus; NSAIDS = nonsteroidal anti-inflammatory drugs; PO = by mouth; SSTI = skin and soft-tissue infections; TID = 3 times daily. Adapted from Jenkins TC, Knepper BC, Sabel AL, et al. Decreased antibiotic utilization after implementation of a guideline for inpatient cellulitis and cutaneous abscess. Arch Intern Med. 2011;171(12):1072-9.
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A male patient with orbital cellulitis with proptosis, ophthalmoplegia, and edema and erythema of the eyelids. The patient also exhibited pain on eye movement, fever, headache, and malaise.
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A male patient with orbital cellulitis with proptosis, ophthalmoplegia, and edema and erythema of the eyelids. The patient also exhibited chemosis and resistance to retropulsion of the globe.
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Gross photograph of complicated cellulitis. Instead of the presence of yellow fat, the tissue is hemorrhagic and necrotic.
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Hematoxylin and eosin (H&E) stain, high power. This image shows deeper subcutaneous tissue involved in a case of cellulitis, with acute inflammatory cells and fat necrosis.
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Hematoxylin and eosin (H&E) stain, high power. This image shows cellulitis caused by herpes simplex virus, with the multinucleated organism in the center of the picture.
