Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ GRAM-POSITIVE BACTERIAL DISEASES +++ Impetigo ++ Superficial nonfollicular infection, due to Staphylococcus aureus or group A Streptococcus, occurs more commonly in children (Fig. 18-1) Lesions can begin as erythematous papules that evolve into a vesicle or pustule. The pustules may rupture leaving contagious honey-colored crusts Treatment: topical mupirocin Bullous impetigo is a toxin-mediated erythroderma (Fig. 18-2) is caused only by Staphylococcus aureus → exotoxin cleaves desmoglein 1 → separation of the epidermis at the granular layer Clinical (seen most frequently in newborns) Sharply demarcated flaccid bullae without surrounding erythema Treatment: dicloxacillin or first-generation cephalosporin, topical mupirocin ++ FIGURE 18-1 Impetigo. (Used with permission from Dr. Steven Mays.) Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 18-2 Bullous impetigo. (Used with permission from Dr. Steven Mays.) Graphic Jump LocationView Full Size||Download Slide (.ppt) +++ Ecthyma ++ Differs from impetigo in that the dermis is ulcerated Usually caused by group A beta-hemolytic streptococci (GABHS) Clinical Thick crusted ulcer that heals slowly and may produce a scar Most commonly affects the lower extremities of children, persons with diabetes, and neglected elderly patient. Often occurs with lymphadenitis Histology: ulceration to dermis with bacteria, crusting and an acute inflammatory infiltrate Treatment: usually dicloxacillin or first-generation cephalosporin, parental antibiotics may be needed for widespread infection +++ Bacterial Folliculitis ++ Most cases caused by S. aureus (Fig. 18-3) Superficial infection: (facial involvement is called Bockhart folliculitis): red papules/pustules, follicularly centered Deep infection: (facial involvement = sycosis barbae); erythematous, fluctuant nodules Lupoid sycosis: chronic form of sycosis barbae associated with scarring Treatment: topical antibiotics, systemic antibiotics may be indicated ++ FIGURE 18-3 Folliculitis. (Used with permission from Dr. Steven Mays.) Graphic Jump LocationView Full Size||Download Slide (.ppt) +++ Furuncles/Carbuncles ++ S. aureus most commonly found (Fig. 18-4) Clinical Deep-seated nodules around hair follicle (inflammation involves the subcutis) Multiple furuncles make a carbuncle, evolve from preceding folliculitis Treatment: topical mupirocin and dicloxacillin; if large, then also need drainage ++ FIGURE 18-4 Furuncule. (Used with permission from Dr. Steven Mays.) Graphic Jump LocationView Full Size||Download Slide (.ppt) +++ Abscess ++ Cutaneous abscesses represent a collection of purulent debris in the skin (Fig. 18-5) Usually Staphylococcus aureus (including possibly methicillin-resistant strains) Methicillin-resistant S. aureus: altered cell wall transpeptidase (penicillin-binding protein 2a) carried on staph chromosome cassette mecA – transfer by bacterial plasmids Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) usually carries mecA types I, II, and III – resistance to clindamycin and macrolides (inducible clindamycin resistance detectable by the “D-zone” test). Community-acquired MRSA commonly carries SCCmec IV – more antibiotic susceptibilities – MRSA usually carries an ... Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth