Source control and debridement are very important in SSTIs.
- Folliculitis
- Inflammation of a single hair follicle
- Staphylococcus aureus or Pseudomonas aeruginosa
- Warm compresses to promote drainage, can use Topical agent 2-4x daily for 7 days
- If Pseudomonas, oral ciprofloxacin or levofloxacin
- Furuncles and carbuncles
- Inflammation of a single or multiple hair follicles
- Risk factors: poor hygiene, obesity, steroids, immunosuppression, diabetes
- Staphylococcus aureus (75% of cases)
- Warm compresses to promote drainage, Usually requires incision and drainage.
- May require an oral agent for 5-7 days – Local methicillin resistance patterns can help guide antimicrobial selection.
- Impetigo
- Superficial, contained to the epidermis. Common on the face and in pediatrics
- Highly contagious due to itching, scratching, and poor hand hygiene
- Staphylococcus aureus (bullous), Streptococcus pyogenes (nonbullous)
- Topical agent BID for 5 days – Mupirocin ointment – Retapamulin ointment
- Oral agent, if multiple lesions or ecthyma, for 7 days (Dicloxacillin or cephlaxin, ir MRSA Bactrim, clinda or doxy)
- Clinical pearl: avoid TMP/SMX due to lack of activity against Group A Streptococcus
- Erysipelas
- Superficial, contained to the epidermis with an advancing, sharply demarcated, raised border
- Streptococcus pyogenes
- Oral agent for 5 days
- Cellulitis
- Acutely spreading, erythematous, painful, edematous infection of the epidermis, dermis, and subcutaneous tissue
- Purlent usually staph, non-purlent is usually strep
- Streptococcus pyogenes (Non purulent), Enteric gram negative bacill, Possible anaerobes
- Skin or blood culture is not routinely recommended
- May require incision and drainage (severe infection) Purlent infections need I&D
- Route of administration is determined by severity and rate of progression
- PO: 0-1 SIRS criteria
- IV: ≥2 SIRS criteria
- Duration of therapy: ≥5 days, not to exceed 14 days
- Mild: PenVK, Cephalexin, Diclocillin, Clindaymycin
- Moderate: Pen G, cefazolin, clinda, ceftriaxone (MRSA if risk factors)
- Severe: Vanc + pip/tazo, van + imi/cilastin, vanc + meropenem, with diabetes, corticosteroids can be used
- Clinda is good for toxin mediated strep and staph infection
- Necrotizing fasciitis
- Acute, often rapidly spreading infection in the fascia, subcutaneous fat, or muscle
- Debridement is necessary, antibiotics alone will not cure.
- Types 1, 2, or 3, Can cause skin necrosis, Severe pain beyond the area of redness
- Gas may be evident on imaging, but surgical inspection confirms diagnosis
- Can lead to shock, organ failure, or death
- Staphylococcus aureus, Streptococcus pyogenes, Enteric gramnegative bacilli, Clostridium perfringens, Peptostreptococcus
- Aggressive, multiple surgical debridements (can be a medical emergency) with Gram’s stain, culture and susceptibility of deep tissue samples
- Broad spectrum intravenous antimicrobial therapy
- Meropenem 1 g IV every 8 hours; children and neonates with a postnatal age >7 days: 20 mg/kg per dose every 8h OR ertapenem 1 g IV every 24 h PLUS vancomycin
- Piperacillin/tazobactam 4.5 g every 6 to 8 hours PLUS Vancomycin per pharmacy OR daptomycin 600 mg PO every 12 hours for 7 to 14 days PLUS clindamycin 600 mg IV q8h.
- Ceftriaxone, PLUS metronidazole PLUS vancomycin
- If Group A strep or clostridia suspected, include clindamycin to suppress streptococcal toxin and cytokine production.
- If confirmed Strep necrotizing fasciitis, use high-dose penicillin (4 million units IV every four hours) plus clindamycin 600 mg IVed
- Pyomyositis
- Pain, tenderness, edema overlying a major muscle
- Often accompanied by bacteremia
- Staphylococcus aureus
- Empirical treatment with vancomycin (90% of cases are Staphylococcus)
- Cat scratch disease
- Bartonella henselae
- Mild cases are not treated, azithromycin for 5 days has been shown to relieve the pain of severe lymphadenopathy but shown no reduction in the overall duration of symptoms. Azithromycin dose is 10 mg/kg day 1 and 5 mg/kg days 2 to 5. Individuals weighing greater than or equal to 45 kg can receive the adult (maximum) dose of 500 mg day one and 250 mg day 2 through 5. Immunocompromised patients should be treated to help prevent the progression to severe systemic disease. Antibiotic regimens including rifampin, trimethoprim-sulfisoxazole, and ciprofloxacin are available for severe, disseminated disease.
- Necrotizing, toxic shock
- Streptococcus pyogenes
- Penicillin + clindamycin ( erythema multiforme can be caused by a penicillin adverse reaction)
- IVIG may be considered in serious infections
- Necrotizing, gas gangrene
- Clostridium perfringens or Other clostridial species
- Penicillin + clindamycin
- Necrotizing infection
- Vibrio vulnificus
- Doxycycline + ceftriaxone/cefotaxime or ceftazidine
- Patients with advanced liver disease may be more susceptible
- Necrotizing infection
- Aeromonas hydrophilia
- Doxycycline + either ceftriaxone or ciprofloxacin
- Fournier gangrene
- A rapid, life-threatening infection of the genitals and perineum with a very high mortality rate even with optimal modern medical treatment.
- The basis of successful therapy in Fournier gangrene is early recognition and the rapid initiation of surgical debridement.
- Treatment:
- Carbapenems (imipenem or meropenem 1 g IV every 6-8 hours, ertapenem 1 g IV every 24 hours OR
- Piperacillin-tazobactam (3.375 g IV every 6 hours or 4.5 g IV every 8 hours) PLUS Clindamycin (600 to 900 mg IV every 8 hours) PLUS Vancomycin (15 to 20 mg/kg IV every 8 to 12 hours)
- Daptomycin or linezolid can be substituted for vancomycin. Antifungal agents such as amphotericin B, fluconazole, or similar can be added as needed.
- Alternate regimens include aminoglycosides or fluoroquinolones plus metronidazole.
- In patients who have had exposure to fresh or saltwater, doxycycline can be added for coverage of Aeromonas hydrophilia and Vibrio vulnificus.
- Bubonic plague
- Yersinia pestis • Streptomycin (may substitute gentamicin) or Doxycycline
- Tularemia
- Franciscella tularensis
- Streptomycin or gentamicin (severe) / Doxycycline or tetracycline (mild)
- Glanders
- Burkholderia mallei
- Ceftazidime, imipenem/cilastatin, gentamicin, doxycycline, ciprofloxacin
- *DOXY
- Cutaneous anthrax
- Bacillus anthracis
- Naturally occurring: penicillin VK / Inhaled (bioterrorism): levofloxacin or ciprofloxacin
- Erysipeloid
- Erysipelothrix rhusiopathiae
- Penicillin or amoxicillin
- Fungal infections
- Candida sp. • Aspergillus sp. • Mucor sp. • Fusarium sp. • Trichosporon sp. • Scedosporium sp.
- Candida: Fluconazole or an echinocandin; C. krusei and C. glabrata have fluconazole resistance
- Aspergillus: voriconazole is first line, duration 6-12 weeks
- Mucor: lipid amphotericin B or posaconazole (+/- echinocandin)
- Fusarium: voriconazole or posaconazole
- Biopsy or aspiration of the lesion for microbiological and histological workup is recommended; blood culture should also be obtained
- Viral infections
- Varicella zoster virus (VZV) • Herpes simplex virus (HSV) • Enteroviruses
- For HSV and VZV, acyclovir is preferred •
- Parasitic infections
- Strongyloides stercoralis • Amoeba (Acanthamoeba, Balamuthia) • Trypanosoma cruzi (Chagas disease) • Sarcoptes scabiei
- Strongyloides = ivermectin
- Amoeba = pathogen specific
- Trypanosoma = benznidazole
- Sarcoptes = permethrin or ivermectin
- Others:
- Nocardia: TMP/SMX
- Mycobacterium: requires combination therapy unique to the species
- Cryptococcus: amphotericin B, fluconazole
- Histoplasma: itraconazole
- Osteomyelitis or septic arthritis
- Surgical intervention usually needed
- Treat for at least 8 weeks, but can add on 1-3 months of rifampin, clinda, bactrim, doxy or a FQ. For septic arthritis, 3-4 weeks only
- Bactrim 4 mg/kg plus rifampin 600 mg, linezolid 600 mg BID, or clindamycin 600 mg q 8 hours.
- Vertebral osteomyelitis usually due to IV drug use, increase in ESR or CRP, usually Staph. Get MRI, if endemic Brucella, look for brucella. Treat for 6 weeks with IV or highly bioavailable PO.
- Pediatrics
- Kingella is more common. Need a radiograph to see facture, MRI and bone scans too
- CBC, ESR, CRP are good predictive values for peds and osteomyelitis. CRP normalizes faster in response to clinical improvement
- Cefazolin for Kingella
- Septic joints need surgical drainage
- Osteomyelitis usually responds to antibiotics alone
- Vanc, clinda, bactrim, linezolid, daptomycin, doxycycline, cipro or levo
- If MRSA resistance > 10-15% add MRSA
- Toxic Shock Syndrome = clinda
- Salmonella coverage in sickle cell
- Gram – in young infants
- Up to 3 months old: cefazolin plus gentamicin, ASP or Cefotaxime
- 3-5 years: Cefazolin or Ceftriaxone (Kingella) or Clinda if Kingella is not endemic
- 5 years – IV ASP or cefazolin or clinda if high MRSA
- Decrease in CRP over 50% in 4 days, afebrile for 48 hours, changed from IV to PO, treat IV for at least 4 days then PO 3 weeks.
- Recurrent:
- 2 or more SSTI infections in 6 months.
- Check hygiene
- If among close contacts, consider decolonization – nasal mupirocin BID for 5-10 days +- body decolonization with chlorhexidine baths. Decolonization house mates too
- Oral antibiotics not needed
Quick Guide
| Epidermal/Surface Skin Infections |
| May be Staph (Impetigo & Ecthyma): |
| · Topical: mupirocin (increasing resistance) · MSSA (usually): cephalexin 250 mg PO q6h or 500 mg PO q12h · MRSA suspected (purulence): doxycycline 100 mg PO BID, clindamycin 300 to 450 mg PO q6h, TMP/SMX 1 DS BID · Duration: 7 days |
| May be strep (Erysipelas): |
| · PCN VK 250 to 500 mg PO every 6 to 8 hours · cephalexin 250 mg PO every 6 hours or 500 mg PO every 12 hours · Azithromycin (resistance increasing) 500 mg PO once daily for 1 day, followed by 250 mg PO once daily for 4 days · Duration: 5 days |
| Dermal Skin Infections (Cellulitis) |
| Mild (non-purulent): · Cephalexin 250 mg PO every 6 hours or 500 mg PO q12h for 5 days · Clindamycin 300 to 450 mg PO q6h for 5 days · Doxycycline 100 mg PO BID for 5 days · TMP/SMX 1 DS BID for 5 days Moderate or severe: · Ancef 1 gram IV (2 g if over 80 kg) IV q8h for 7 days OR · Vancomycin per IV protocol for 7 days |
| Purulent: · Vancomycin IV per pharmacy protocol for 14 days plus cefazolin 1 g IV (unless patient is over 80 kg, then give 2 g) q8h for 14 days · Vancomycin IV per pharmacy protocol for 14 days and cefepime 2 g IV q8h for 14 days · Can add metronidazole if anaerobes suspected (diabetic foot, involvement of axilla, gastrointestinal tract, perineum, or female genital tract) · Vancomycin IV per pharmacy protocol for 14 days PLUS piperacillin/tazobactam 4.5g IV q6h for 14 days (higher risk of nephrotoxicity) An antibiotic active against MRSA (vancomycin) is recommended for patients with carbuncles or abscesses who have failed initial antibiotic treatment or have markedly impaired host defenses or in patients with SIRS and hypotension |
| Special Populations and Pathogens to Consider for Cellulitis | |
| Immunocompromised or patients who have failed previous therapy | Consider gram-negatives |
| IV Drug Users | S. aureus, S. pyogenes – most common Gram-negatives, anaerobes – less common; Candida – rarely |
| Diabetics / pressure sores | mixed aerobic/anaerobic flora; may progress to areas of gangrene |
| Abscesses | Consider gram-positives; less commonly gram-negatives or anaerobes Often requires drainage for primary management |
Surgical Site Infections
- Suture removal plus incision and drainage should be performed for surgical site infections
- Adjunctive systemic antimicrobial therapy is not routinely indicated, but in conjunction with incision and drainage may be beneficial for surgical site infections associated with a significant systemic response
- A brief course of systemic antimicrobial therapy is indicated in patients with surgical site infections following clean operations on the trunk, head and neck, or extremities that also have systemic signs of infection
| Cefazolin 2 g (3g if > 120 kg) IV q8h OR nafcillin 2 g IV q6h OR cephalexin 500 mg q6h PO OR sulfamethoxazole-trimethoprim 160-800 mg q6h if no MRSA risk factors |
| Vancomycin per pharmacy where risk factors for MRSA are high (nasal colonization, prior MRSA infection, recent hospitalization, recent antibiotics), is recommended |
| If GI or female genital tract involvement, piperacillin-tazobactam 3.375 g q6h or 4.5 g q8h IV, OR meropenem 1 g q8h, OR ceftriaxone 1 g q24h PLUS metronidazole 500 mg q8h, OR levofloxacin 750 mg daily IV |
Animal and Human Bites, Rabies
Usually Staphylococcus aureus, Streptococcus, including viridans group, Eikenella corrodens, Anaerobes(Peptostreptococcus sp., Peptococcus sp., Fusobacterium sp., Prevotella sp.), Corynebacterium sp.
| Bites | |
| Animal | · Amoxicillin/clavulanate 875/125 mg q12h Alternatives: · Clindamycin 200 mg TID plus ciprofloxacin 500 mg BID · Doxycycline 100 mg BID · Penicillin VK 500 mg 4 times PLUS dicloxacillin 500 mg 4 times a day · Levaquin 500 mg q24h · Trimethoprim/sulfamethoxazole 160/800 mg PO BID · Cefuroxime 500 mg BID PLUS metronidazole 250 mg QID · Clindamycin 300 mg TID |
| Human | · Amoxicillin-clavulanate 875/mg q12h Alternatives: · Doxycycline 100 mg BID · Penicillin VK 500 mg 4 times · Trimethoprim/sulfamethoxazole 160/800 mg PO BID · Cefuroxime 500 mg BID · Ciprofloxacin 500 mg BID · Levaquin 750 mg BID |
| Suspicion for Water Pathogens (hot tubs, lakes) | · Ceftriaxone 2 G IV q14h Alternatives: · Levofloxacin 750 mg IV or PO q24h · Consult ID, may be parasitic |
Consider Rabies prophylaxis if:
- Bat bites, mammals showing signs of rabies, or who were sick or died after the bite. Physicians can contact their local health department or go to http://www.cdc.gov/rabies/resources/contacts.html for a list of state and local rabies consultation contacts.
- Prophylaxis consists of immune globulin at presentation and rabies vaccination on days 0, 3, 7, and 14. The immune globulin is infiltrated around the bite wound, and any additional volume is administered at a site distant to the vaccination site, usually the opposite arm as the rabies vaccine. If the patient had already received preexposure prophylaxis before the animal bite, no immune globulin is needed, and the rabies vaccine is administered only on days 0 and 3.
Consider Tetanus Vaccine if:
- Vaccine status uncertain or patient has received less than 3 vaccines or if it has been more than 10 years since last vaccine for a clean wound or less than 5 years for all other wounds.