Antibiotics for Skin and Soft Tissue Infections PDF

1/1/25 1 2 Antibiotics for Skin and Soft Tissue Infections 3 Cellulitis The most common etiology of cellulitis with purulent drainage is S. aureus, group A streptococci and other streptococcal species Treatment - coverage for MSSA, community-acquired MRSA (CA- MRSA), an...

1/1/25 1 2 Antibiotics for Skin and Soft Tissue Infections 3 Cellulitis The most common etiology of cellulitis with purulent drainage is S. aureus, group A streptococci and other streptococcal species Treatment - coverage for MSSA, community-acquired MRSA (CA- MRSA), and streptococci Oral Regimens Doxycycline 100 mg PO BID PLUS Cephalexin 500 mg PO QID OR Amoxicillin 500 mg PO TID OR TMP/SMX 1-2 DS tab PO BID PLUS Amoxicillin 500 mg PO TID* OR Clindamycin 300 mg PO TID *TMP/SMX and doxycycline have poor activity against Group A streptococci and should be combined with Amoxicillin or Cephalexin. 4 Cellulitis Treatment: IV Vancomycin (moderate to severe disease or nosocomial acquisition) OR Clindamycin 600 mg IV q8h (mild disease) Duration: 7-10 days. May step down to oral therapy when patient is improving. 5 Folliculitis - S. aureus, P. aeruginosa (hot tub) - Warm compresses, no antibiotics Furuncles, carbuncles, “boils” - S. aureus, including CA-MRSA - I and D; if fever and/or surrounding cellulitis, “oral regimens” Abscesses - S. aureus, including CA-MRSA – I and D, if surrounding cellulitis, systemic symptoms, and/or multiple lesions - “oral 6 1  Abscesses - S. aureus, including CA-MRSA – I and D, if surrounding cellulitis, systemic symptoms, and/or multiple lesions - “oral regimens”; if gangrene, immunocompromised, extensive surrounding cellulitis, or severe systemic symptoms: consider surgical treatment, Vancomycin 6 Impetigo - S. aureus, including CA-MRSA, S. pyogenes - Warm water soak, oral therapy Erysipelas - S. pyogenes, rarely S. aureus, or S. agalactiae - PCN VK 250-500 mg PO QID, Clindamycin 300 mg PO/600 mg IV TID; If MRSA, add TMP/SMX DS BID Cellulitis - S. aureus, including CA-MRSA, S. pyogenes: mild: oral therapy; moderate: parenteral therapy; diabetics: mixed anaerobic and aerobic flora - Mild: Amoxicillin/clavulanate 875 mg PO BID OR Ciprofloxacin 500 mg PO BID] PLUS Clindamycin 300 mg PO TID; Moderate/severe: Piperacillin/tazobactam 3.375 g IV q6h OR Meropenem 500 mg IV q8h. If concern for MRSA, add vancomycin; Severe PCN allergy: Ciprofloxacin + Clindamycin OR Aztreonam + Clindamycin. If concern for MRSA, use vancomycin instead of clindamycin and add anaerobic coverage with metronidazole 7 Cellulitis Microbiology - S. aureus and Streptococci (especially Group A) Management: Always elevate the affected extremity Improvement of erythema can take days (venous stasis or lymphedema) Resistance to fluoroquinolones in S. aureus is common Rifampin should NEVER be used as monotherapy because resistance develops rapidly There is NO EVIDENCE that linezolid or daptomycin are superior to TMP/SMX, doxycycline, or clindamycin Linezolid or daptomycin – just resistance to other agents Elimination or prevention of interdigital tinea 8 Cellulitis Other causes of cellulitis in select patient populations: With bullae, vesicles, and ulcers after exposure to seawater or raw oysters, consider Vibrio vulnificus - treat with ceftriaxone 1 g IV 8 With bullae, vesicles, and ulcers after exposure to seawater or raw oysters, consider Vibrio vulnificus - treat with ceftriaxone 1 g IV q24h PLUS doxycycline 100 mg PO BID Neutropenic, solid organ transplant, and cirrhotic patients may have cellulitis due to gram-negative organisms Animal and human bites: Pasteurella multocida should be covered for cat and dog bites. Treat with Amoxicillin/clavulanate 875 mg PO BID OR Ampicillin/sulbactam 1.5-3 g IV q6h. If PCN allergy: Ciprofloxacin 500 mg PO / 400 mg IV q24h PLUS Clindamycin 300 mg PO TID/600 mg IV q8h. Remember to consider tetanus booster and/or rabies vaccination 9 Cutaneous Abscess Incision and drainage - the primary treatment; culture and sensitivity testing Indications for antimicrobial therapy in patients with cutaneous abscesses: Severe or rapidly progressive infections The presence of extensive associated cellulitis Signs and symptoms of systemic illness Diabetes or other immune suppression (e.g., solid organ transplant) Advanced age Location of the abscess in an area where complete drainage is difficult Lack of response to I and D alone Antibiotic therapy should be given before I and D in patients with prosthetic heart valves or other conditions placing them at high risk for endocarditis Treatment: One of this indications: same as for cellulitis; if CA-MRSA is strongly suspected or confirmed, consider NOT adding Amoxicillin or Cephalexin to TMP/SMX, Doxycycline, or Clindamycin 10 Recurrent MRSA Skin Infections Patient education regarding approaches to personal and hand hygiene Decontamination of the environment Topical decolonization (consider if a patient has ≥ 2 episodes per year or other household members develop infection) 11 10 Topical decolonization (consider if a patient has ≥ 2 episodes per year or other household members develop infection) Evaluation of family members 11 Diabetic Foot Infections Treatment - depends on clinical severity Uninfected - No purulence or inflammation Mild - Presence of purulence and ≥ 1 signs of inflammation* and cellulitis (if present) ≤ 2 cm around ulcer limited to skin or superficial subcutaneous tissue Moderate - Same as mild PLUS ≥ 1 of the following: > 2 cm of cellulitis, lymphangitic streaking, spread beneath the superficial fascia, deep tissue abscess, gangrene, involvement of muscle, tendon, joint, or bone Severe - Any of the above PLUS systemic toxicity or metabolic instability *Erythema, pain, tenderness, warmth, induration 12 Diabetic Foot Infections MILD INFECTIONS Oral Regimens Cephalexin 500 mg PO QID OR Clindamycin 300 mg PO TID (covers MRSA) OR Amoxicillin/clavulanate 875 mg PO BID IV Clindamycin 600 mg IV q8h (covers CA-MRSA if no inducible Clindamycin resistance) OR Cefazolin 1 g IV q8h 13 Diabetic Foot Infections MODERATE INFECTIONS Ertapenem 1g IV q24h OR Ciprofloxacin 500 mg PO BID / 400 mg IV q12h PLUS EITHER Clindamycin 600 mg IV q8h/300 mg PO TID OR Metronidazole 500 13 Ciprofloxacin 500 mg PO BID / 400 mg IV q12h PLUS EITHER Clindamycin 600 mg IV q8h/300 mg PO TID OR Metronidazole 500 mg IV/PO TID Avoid fluoroquinolones in patients who were on them as outpatients If patient at risk for MRSA, add Vancomycin to regimens that do not include Clindamycin Risk factors for MRSA History of colonization or infection with MRSA Recent (within 3 months) or current prolonged hospitalization > 2 weeks Transfer from a nursing home or subacute facility Injection drug use 14 Diabetic Foot Infections SEVERE INFECTIONS Piperacillin/tazobactam 4.5 g IV q6h OR Ciprofloxacin 400 mg IV q12h PLUS Clindamycin 600 mg IV q8h BUT avoid fluoroquinolones in patients who were on them as outpatients If patient at risk for CA-MRSA: Piperacillin/tazobactam 4.5 g IV q6h PLUS Vancomycin If patient at risk for CA-MRSA OR Ciprofloxacin 400 mg IV q12h PLUS Metronidazole 500 mg IV q8h PLUS Vancomycin BUT avoid fluoroquinolones in patients who were on them as outpatients 15 Diabetic Foot Infections Microbiology Cellulitis without open wound or infected ulcer, antibiotic naive: beta-hemolytic streptococci, S. aureus Infected ulcer, chronic or previously treated with antibiotics: S. aureus, beta-hemolytic streptococci, Enterobacteriaceae Exposure to soaking, whirlpool, hot tub: usually polymicrobial, can involve Pseudomonas  Exposure to soaking, whirlpool, hot tub: usually polymicrobial, can involve Pseudomonas Chronic wounds with prolonged exposure to antibiotics: aerobic gram positive cocci, diphtheroids, Enterobacteriaceae, other gram negative rods including Pseudomonas Necrosis or gangrene: mixed aerobic gram positive cocci and gram negative rods, anaerobes 16 Diabetic Foot Infections Diagnosis: Cultures of the ulcer base after debridement can help guide therapy Ulcer floor should be probed carefully. If bone can be touched with a metal probe then the patient should be treated for osteomyelitis with antibiotics in addition to possible surgical debridement Avoid swabbing non-debrided ulcers or wound drainage A deep foot-space infection can be present. Consider imaging to look for deep infections Putrid discharge is diagnostic for the presence of anaerobes MRI is more sensitive and specific than other imaging for detection of soft-tissue lesions and osteomyelitis 17 Diabetic Foot Infections Duration: Duration of treatment will depend on presence of adequate blood supply or osteomyelitis Likely need shorter treatment with adequate surgical intervention (7-10 days post-op) and longer for osteomyelitis Change to an oral regimen when patient is stable 18 Surgical Site Infections (SSI) Treatment Infections following clean procedures (e.g. orthopedic joint replacements, open reduction of closed fractures, vascular procedures, median sternotomy, craniotomy, breast and hernia procedures) Cefazolin 1 g IV q8h OR PCN allergy: Clindamycin 600 mg IV q8h OR Involvement of hardware: Vancomycin 19  OR Involvement of hardware: Vancomycin Exception: Saphenous vein graft harvest site infections should be treated with ertapenem 1 g IV q24h 19 Surgical Site Infections (SSI) Infections following contaminated procedures (GI/GU procedures, oropharyngeal procedures, OB/GYN procedures) Patients not on broad-spectrum antibiotics at time of surgery and not severely ill: Ertapenem 1 g IV q24h OR Severe PCN allergy: Ciprofloxacin 500 mg PO BID/400 mg IV q12h) PLUS Clindamycin 600 mg IV q8h 20 Surgical Site Infections (SSI) Patients on broad-spectrum antibiotics at time of surgery or severely ill: Piperacillin/tazobactam 3.375 g IV q6h PLUS Vancomycin, if hardware present or MRSA suspected OR PCN allergy: Vancomycin PLUS Ciprofloxacin 500 mg PO BID/400 mg IV q12h) PLUS Metronidazole 500 mg PO/IV q8h Deep fascia involvement - Treat as necrotizing fasciitis 21 Surgical Site Infections (SSI) Microbiology Following clean procedures (no entry of GI/GU tracts) Staphylococcus aureus (including MRSA) Streptococci, group A (esp with early onset, < 72 hours) Coagulase-negative staphylococci Following clean-contaminated and contaminated procedures (entry of GI/GU tracts with or without gross contamination) Organisms above Gram-negative rods Anaerobes (consider Clostridia spp in early-onset infections, 1-2 days) 22 Surgical Site Infections (SSI) Risk factors for MRSA History of colonization or infection with MRSA 23 22 Risk factors for MRSA History of colonization or infection with MRSA Recent (within 3 months) or current prolonged hospitalization >2 weeks Transfer from a nursing home or subacute facility Injection drug use 23 Necrotizing Fasciitis (serious, deep-tissue infections) THESE ARE SURGICAL EMERGENCIES. ANTIBIOTICS ARE ONLY AN ADJUNT TO PROMPT SURGICAL DEBRIDEMENT Treatment: Vancomycin PLUS [Piperacillin/tazobactam 3.375 g IV q6h OR Cefepime 1 g IV q8h] PLUS Clindamycin 600-900 mg IV q8h OR PCN allergy: Vancomycin PLUS Ciprofloxacin 400 mg IV q12h PLUS Clindamycin 600-900 mg IV q8h If confirmed beta-hemolytic streptococci: Penicillin G 24 Million Units as continuous infusion PLUS Clindamycin 600-900 mg IV q8h OR PCN allergy: Vancomycin PLUS Clindamycin 600-900 mg IV q8h 24 Necrotizing Fasciitis (serious, deep-tissue infections) Conventional nomenclature and microbiology Pyomyositis (purulent infection of skeletal muscle, usually with abscess formation) S. aureus most commonly Clostridial myonecrosis - Clostridia spp (esp C. perfringens) Group A streptococcal myonecrosis Fasciitis (infection of the subcutaneous tissue that results in progressive destruction of fascia and fat, but may spare the skin) Type 1 - Polymicrobial infections with anaerobes, streptococci and gram-negative rods (Fournier’s gangrene is a type 1 necrotizing fasciitis of the perineum) Type 2 - Group A streptococci Cases of fasciitis caused by community-acquired MRSA have been reported Case-cohort studies and case reports have suggested some benefit to treatment with intravenous immunoglobulin (IVIG) in specific circumstances (e.g., streptococcal toxic shock); reserve for 25  benefit to treatment with intravenous immunoglobulin (IVIG) in specific circumstances (e.g., streptococcal toxic shock); reserve for select patients 25 Necrotizing Fasciitis (serious, deep-tissue infections) Diagnosis Can be difficult - gas production is not universal and is generally absent in streptococcal disease Can follow minor or major trauma, especially when risk factors are present Maintain high index of suspicion when: Patients are very ill from cellulitis (hypotension, toxic) Pain out of proportion to exam findings Anesthesia over affected area Risk factors such as diabetes, recent surgery, or obesity Findings such as skin necrosis or bullae Putrid discharge with thin, “dishwater” pus CT scan can help with diagnosis but if suspicion is moderate to high, surgical exploration is the preferred diagnostic test. DO NOT delay surgical intervention to obtain CT Initial histopathologic findings may be of prognostic importance. A poor neutrophil response with numerous organisms seen on routine stains implies a poor prognosis