Bacterial Infections E.J. Mayeaux, Jr., M.D. Professor of Family Medicine Professor of Obstetrics & Gynecology Louisiana State University Health Sciences Center Shreveport, LA No disclosures to report. Objectives Differentiate common bacterial skin infections. Construct appropriate diagnostic and treatment plans for various infections, including cases involving multidrug-resistant organisms such as MRSA. Impetigo Acute highly contagious gram-positive epidermal bacterial infection Most common skin infection in children More common in hot, humid climates More common on the face or extremities Bullous (30%) and nonbullous (70%) forms 1
Impetigo Presentation Nonbullous impetigo Group A B-hemolytic streptococci (GABHS or Streptococcus pyogenes) and/or Staph aureus Golden Begins as strep infection but staph may replace Courtesy of the Color Atlas of Family Medicine Impetigo Presentation Bullous impetigo Mostly by S aureus Forms blisters Toxin-mediated Epidermis sloughs Not MRSA Courtesy of the Color Atlas of Family Medicine Impetigo Treatment Local wound care and antibiotic therapy Gentle cleansing & removal of crusts Frequent application of wet dressings Good hygiene with antibacterial washes Staph + Strep antibiotic therapy MRSA causes folliculitis or abscess not impetigo 2
Topical Impetigo Abx Treatment Mupirocin oint 2-3x daily for 7-days Better than topical polymyxin B and neomycin MRSA resistance 5-10% Retapamulin (Altabax) oint. 2x daily for 5 days Not for mucosal use Activity against bacteria resistant to multiple abx Clindamycin topicals for MRSA infections Stevens DL, et al. Clin Infect Dis. Nov 15 2005;41(10):1373-406. Systemic Impetigo Abx Treatment Beta-lactamase resistant antibiotics Cephalosporins, Amoxicillin-clavulanate Cloxacillin or dicloxacillin MRSA suspected Clindamycin Tmp-sfx Vancomycin Erythromycin & clindamycin for PCN allergy Stevens DL, et al. Clin Infect Dis. Nov 15 2005;41(10):1373-406. Impetigo Prevention Discourage contact with lesions Inspect household members Proper care of insect bites/minor trauma Do not return to daycare or school until 24 hours after initiation of antimicrobial tx Recurrence: 2% mupirocin crm/oint inside nostrils 3x daily for 5 days each month 3
The organism(s) most likely to cause cellulitis are: A. Staphylococcus aureus and Streptococcus species B. Pseudomonas and Streptococcus species C. Haemophilus species D. Streptococcus species and Atypical mycobacterium Introduction Incidence ~200/100,000 patient-yrs McNamara DR, et al. Mayo Clin Proc 2007; 82:817. Most skin infections caused by: Streptococci (secondary invaders) Impetigo, erysipelas, and lymphangitis S. aureus (invades skin) Impetigo, folliculitis, and furuncles Toxins cause bullous impetigo & SSSS Cellulitis and Erysipelas Cellulitis and erysipelas are skin infections characterized by erythema, heat, pain (rubor, calor, dolor), and edema 4
Cellulitis Infection of the dermis & SQ tissue Usually group A strep & S. aureus Recurrences with compromise of venous or lymphatic circulation Cellulitis Expanding, red, swollen, tender plaque with indefinite border Chills, fever, edema, bullae Courtesy of the Color Atlas of Family Medicine Cellulitis Near trauma but also in normal skin Pedal fungal infections 5
Erysipelas Acute, inflammatory cellulitis with lymphatic involvement ("streaking") More superficial - margins more clearly demarcated Lower extremity more common Hugo-Persson M, Norlin K. Infection 1987; 15:36-9 Erysipelas St. Anthony's Fire - facial erysipelas Courtesy of the Color Atlas of Family Medicine Erysipelas Prodromal symptoms last 4-48 hrs Malaise, chills, fever (101 to 104 F), and occ. anorexia and vomiting Tender, firm, rapidly expanding spots Tense, red, hot, uniformly elevated, shining patch with sharp raised border Becomes dark, fiery red; forms vesicles Itching, burning, tenderness, and pain 6
True statements about cellulitis infections include: A. MRSA is resistant to all beta-lactam agents except cephalosporins B. Nonpurulent cellulitis without prior antibiotics or abscess should be treated like non-mrsa infections C. MRSA causes shallower but much wider infections D. Patients with illegal drug use are not at increased risk for MRSA MRSA Shortly after introduction of methicillin in 1959, MRSA reported Resistant to all beta-lactam agents including cephalosporins Mediated by meca gene Encodes for low-affinity binding protein Increasingly prevalent community-associated pathogen Community-Acquired MRSA Have different antimicrobial susceptibility characteristics from healthcare-associated (HA) MRSA 2004 ER study, MRSA was isolated from 51% of infection cultures Causes deeper infections Edge exfoliation 7
Community-Acquired MRSA RISK FACTOR OR (95% CI) Contact with a person with similar infection 3.4 (1.5-8.1) History of MRSA infection 3.3 (1.2-10.1) Snorting or smoking illegal drugs 2.9 (1.2-6.8) Incarceration within previous 12 months 2.8 (1.1-7.3) Reported spider bite 2.8 (1.5-5.3) Antibiotics in past month 2.4 (1.4-4.1) Abscess 1.8 (1.0 Older age (odds ratio per decade of life) 0.9 (0.9-1) Underlying illness 0.3 (0.2-0.6) Presentation with a nonskin infection 0.3 (0.1-0.8) Adapted from: Miller LG, et al. Clin Infect Dis. 2007;44:471-482. and Moran GJ, et al. N Engl J Med. 2006;355:666-674.. Diagnosis of Cellulitis Clinical features Poor isolation of the etiologic agent Leading-edge and midpoint aspirates of little value in normal hosts Hook EW, et al. Arch Intern Med 1986; 146:295-7 More bacteria at point of maximum inflammation Howe PM, et al. Pediatr Infect Dis J 1987; 6:685-6 Blood cultures are not cost-effective and are more frequently contaminated than positive with uncomplicated cellulitis Since introduction of the H. flu type b vaccine, the most common organisms are streptococci http://www.mrw.interscience.wiley.com/cochrane/ cleed/articles/nhseed-980460/frame.html 8
Diagnosis of Cellulitis Fever, mild leukocytosis, and a mildly elevated sed rate Other ds - culture more productive DM, heme Ca, IV drugs, HIV, chemo Children - Most common causes are S. aureus, S. pyogenes, H. influenzae, and S. pneumoniae Poor isolation of the etiologic agent Tx of Cellulitis - Nonpurulent Oral therapy Adults Children Dicloxacillin 500 mg Q6 hours 25-50 mg/kg/day in 4 doses Cephalexin 500 mg Q6 hours 25-50 mg/kg day in 3-4 doses Clindamycin 300 to 450 mg Q6-8 hours Intravenous therapy Cefazolin Oxacillin Nafcillin 1 to 2 grams Q8 hours 20 to 30 mg/kg/day in 4 doses 100 mg/kg/day in 3-4 doses 2 grams Q4 hours 150-200 mg/kg/day in 4-6 doses 2 grams Q4 hours 150-200 mg/kg/day in 4-6 doses Clindamycin 600-900mg Q8 hr 25-40 mg/kg/day in 3-4 doses Liu C, et al. Clin Infect Dis. 2011; 52(3):e18-55. Tx of Cellulitis Erysipelas For adults For children Oral therapy Penicillin 500 mg Q 6 hours 25-50 mg/kg/day in 3-4 doses Amoxicillin 500 mg Q 8 hours 25-50 mg/kg/day in 3 doses Erythromycin 250 mg Q 6 hours 30-50 mg/kg/day in 2-4 doses Parenteral therapy Ceftriaxone 1g Q 24 hours 50-75 mg/kg/day in 1-2 doses Cefazolin 1 to 2 g Q 8 hours 100 mg/kg/day in 3 doses Liu C, et al. Clin Infect Dis. 2011; 52(3):e18-55. 9
Treatments for purulent cellulitis infection include all of the following except: A. Cephalexin 500 mg Q6 hours B. Clindamycin 300 to 450 mg orally TID C. Trimethoprim-sulfamethoxazole 1 to 2 DS tab orally BID D. Doxycycline 100 mg orally BID Tx of Cellulitis - Purulent Treatment (MRSA) Clindamycin Trimethoprimsulfamethoxazole Doxycycline Minocycline Linezolid Adult dose 300 to 450 mg orally TID 1 to 2 DS tab orally BID 100 mg orally BID 200 mg orally once, then 100 mg orally BID 600 mg orally BID Ceftaroline (Teflaro) IV cephalosporin against MRSA Liu C, et al. Clin Infect Dis. 2011; 52(3):e18-55. Tx of Cellulitis MRSA + Strep Antibiotic agent Clindamycin Amoxicillin PLUS Trimethoprim-sulfamethoxazole Amoxicillin PLUS Doxycycline Amoxicillin PLUS Minocycline Linezolid Dose 300 to 450 mg orally TID 500 mg orally TID 1-2 DS tabs orally BID 500 mg orally TID 100 mg orally BID 500 mg orally TID 200 mg, then 100 mg orally BID 600 mg orally BID Emycin resistance may = clindamycin resistance Liu C, et al. Clin Infect Dis. 2011; 52(3):e18-55. 10
Pseudomonas Cellulitis Localized or with septicemia Localized form is secondary infection Encouraged by maceration & occlusion Severe pain highly characteristic Pseudomonas Cellulitis The skin turns a dusky red Bluish green, purulent material with a fruity or "mousey" odor as red, indurated area becomes macerated Satellite vesicles and pustules dev. Deep erosions and tissue necrosis may occur before dx made Pseudomonas Cellulitis Pseudomonas septicemia Deep, indurated, necrotic cellulitis Ciprofloxacin 500 or 750 mg BID 5% acetic acid wet compresses applied 20 minutes QID 11
True statements about folliculitis include: A. It heals with some scarring B. It may be a complication of occlusive topical steroid therapy C. It is best treated with oral antibiotics D. Recurrences are rare Folliculitis Inflammation of hair follicle by infection, chemical irritation, or injury Associated with variety of skin ds Pustule that heals without scarring Hair shaft often not seen May become a furuncle or abscess if extends through the dermis Several may coalescence into a carbuncle Folliculitis Swollen, red mass - eventually points toward the surface 12
Staph Folliculitis Most common infectious form One or more pustules No systemic symptoms Injury, abrasion, nearby surgical wounds, or draining abscesses Complication of occlusive topical steroid therapy Staph Folliculitis Courtesy of Dr..Richard Usatine Folliculitis Localized treated with topical abx (mupirocin) Extensive disease - oral antibiotics for 2 weeks or inflammation cleared Erythromycin Dicloxacillin Cephalexin Recurrences common 13
Pseudomonas Folliculitis A.k.a. Hot tub folliculitis Temp skin moisture = overgrowth Contaminated whirlpool, hot tub, waterslide, physiotherapy pool, or loofah sponges Courtesy of Dr. Richard Usatine Pseudomonas Folliculitis Children > adults Tend to spend more time in water Showering offers no protection Pseudomonas Folliculitis 0.5- to 3-cm, pruritic, round, urticarial plaques with a central pustule All skin surfaces except the head Most severe where occluded by snug bathing suit Eruption clears in 7 to 10 days Leaves round spots of red-brown, postinflammatory hyperpigmentation 14
Pseudomonas Folliculitis Malaise and fatigue initial few days Fever uncommon Correction of altered environment results in resolution Treatment with oral fluoroquinolones True statements about abscesses include all of the following except: A. They are walled-off, cavity with finger-like loculations of granulation tissue and pus B. They are common in children C. Streptococci most common cause D. Primary treatment is cephalexin or other Staph antibiotic Abscesses Walled-off collection of pus Painful, firm, and fluctuant Cellulitis before or with it Uncommon in children Not a hollow sphere, but a cavity formed by fingerlike loculations of granulation tissue and pus Courtesy of E.J. Mayeaux, Jr., M.D. 15
Abscesses Appear in areas prone to friction Under belt, the anterior thighs, buttocks, groin, axillae, and waist S. aureus Anterior nares 1 o site disseminated Microbiology = microflora of the anatomic part of the body involved 5% of abscesses are sterile Abscesses Factors for hair follicle infection Occlusion of groin and buttocks - especially in hyperhidrosis Follicular abnormalities Hidradenitis suppurativa Atopic dermatitis and eczema Courtesy of E.J. Mayeaux, Jr., M.D. Abscesses Warm compresses I&D - No culture or abx Wait till pointing Anesthetized with 1% lidocaine Insert #11 blade, cut parallel to skin lines Avoid extending noneffaced skin Break adhesions Continuous drainage - gauze 16
Abscesses Culture & gram stain For recurrent abscesses, tx failure, toxicity, involvement of the central face, deep, or immunocompromised Insert needle through skin over abscess Gram stain provides a rapid diagnosis Abx - recurrent abscesses Little effect once has become fluctuant 17