Principles of Therapy
Choice of Route of Administration for Empiric Treatment
Oral Antibiotics
- If lymphadenopathy, fever & other constitutional signs are not present [eg white blood cells (WBC) <15,000], then may typically treat patient w/ oral antibiotics on an outpatient basis
Parenteral Antibiotics
- If symptoms do not improve or if disease progresses significantly w/in the first 24-48 hours parenteral therapy may be needed
- If lymphadenopathy, fever or constitutional signs are present
- Neonates should be admitted & given initial parenteral therapy if w/ moderate to severe presentation
- Considered in patients w/ comorbidities [eg diabetes mellitus (DM), peripheral vascular diseases]
Choice of Antibiotic
- Tailored according to known pathogen, comorbid condition, & special situations like water (eg salt or freshwater) exposure or animal bites
- Treatment should also address underlying predisposing conditions
- Empiric therapy may be started pending culture results
- For patients w/ purulent cellulitis, treatment is directed towards Methicillin-resistant S aureus (MRSA) since it is the dominant pathogen in this type of cellulitis; therapy for beta-hemolytic streptococci is likely not needed
- For patients w/ nonpurulent cellulitis, treatment is directed towards Methicillin-sensitive S aureus (MSSA) & beta-hemolytic streptococci
- Empiric therapy for MRSA may be needed if patient has signs of systemic infection, is unresponsive to initial therapy, has recurrent infection, or has a previous episode of or is at high risk for MRSA infection
Penicillins (Beta-lactamase resistant)
- Recommended therapy for patients w/ erysipelas, moderate nonpurulent & purulent cellulitis, & MRSA infection
- Recommended antibiotics against mild nonpurulent cellulitis caused by group A Streptococcus or S aureus
- Some authorities recommend antistaphylococcal penicillin alone while others advocate antistaphylococcal penicillin + Penicillin or Amoxicillin
- Combination may increase adverse effects
- Recommended for initial treatment of neonates w/ moderate to severe cellulitis
- Also recommended for recurrent cellulitis
Pharmacotherapy
Penicillin G [Intravenous (IV)]
- Used for erysipelas & moderate nonpurulent uncomplicated cellulitis
- Treatment option for patients w/ recurrent cellulitis
- Observe patient for localized S aureus infection
Cephalosporins (1st Generation)
- If staphylococcal infection is suspected
- Usually sufficient for mild nonpurulent uncomplicated cellulitis
Cephalosporins (2nd & 3rd Generation) [Parenteral]
- Usually used empirically in diabetes mellitus (DM) patients who have early mild cellulitis
- Treatment alternative for patients w/ moderate nonpurulent cellulitis
Aminopenicillin/Beta-Lactamase Inhibitors
- Considered 2nd-line alternative by some authorities
- Effective & especially useful in the presence of bone or joint infection
Macrolides
- Eg Erythromycin, Roxithromycin
- May be used if patient is allergic to Penicillin
- Macrolide resistance among Group A Streptococci has increased & has become a concern in some countries
- Erythromycin is the main macrolide used unless Erythromycin resistance is widespread in the community
- Also used for prophylactic treatment against recurrent cellulitis
- Studies showed that the efficacy of Roxithromycin for erysipelas was comparable to that of Benzylpenicillin
Other Antibiotics
- Clindamycin
- Used in patients allergic to Penicillin & cephalosporins
- Alternative therapy for patients w/ nonpurulent or purulent cellulitis caused by Methicillin-sensitive S aureus (MSSA) or Methicillin-resistant S aureus (MRSA) infection
- Co-trimoxazole
- Used for nonpurulent cellulitis & moderate purulent cellulitis
- Has very good activity against community-acquired MRSA but not to streptococci
- Linezolid
- Used in patients allergic to Penicillin & for complicated cellulitis & erysipelas
- Vancomycin
- Treatment option for patients allergic to Penicillin
- Combination w/ Piperacillin/Tazobactam or Imipenem/Meropenem is recommended for patients w/ severe nonpurulent cellulitis
- Combination w/ Cefotaxime or Gentamicin is recommended as 1st-line parenteral treatment for neonates w/ MRSA infections
- Also used for patients w/ penetrating trauma, nasal colonization w/ MRSA, & IV drug use
Quinolones
- Eg Ciprofloxacin, Levofloxacin, Moxifloxacin, Ofloxacin
- Those that have enhanced activity against Gram-positive bacteria have been shown to be effective
- Used for cellulitis caused by Vibrio vulnificus
- Not recommended for patients living in MRSA-prevalent regions
Tetracyclines
- Eg Doxycycline, Minocycline
- May be considered for moderate-severe purulent cellulitis, MSSA, & MRSA infections
Length of Therapy
- It is typically recommended that once erythema, warmth & edema have subsided significantly, patient may be treated for an additional 10 days w/ oral antibiotics
- Antibiotic therapy for neonates is usually administered for 7-10 days; 5-10 days for patients >1 month
- Treatment duration may be extended for severe cases