PHA6784 SSTI Lecture.pdf

Skin & Soft Tissue Infections (SSTIs) PHA6784 Integrated Therapeutics III Infectious Diseases Module Oct 3rd, 2024 Melissa O’Neal, PharmD | [email protected] Lecture Objectives Review structure of the skin and pathophysiology behind skin infections Differentiate between common skin and soft t...

Skin & Soft Tissue Infections (SSTIs) PHA6784 Integrated Therapeutics III Infectious Diseases Module Oct 3rd, 2024 Melissa O’Neal, PharmD | [email protected] Lecture Objectives Review structure of the skin and pathophysiology behind skin infections Differentiate between common skin and soft tissue infections Apply guidelines to clinical practice & create therapeutic plans for patient cases 2 Readings Required Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America [published correction appears in Clin Infect Dis. 2015 May 1;60(9):1448. Dosage error in article text]. Clin Infect Dis. 2014;59(2):e10-e52. Supplemental Senneville É, Albalawi Z, van Asten SA, et al. IWGDF/IDSA Guidelines on the Diagnosis and Treatment of Diabetes-related Foot Infections (IWGDF/IDSA 2023) [published correction appears in Clin Infect Dis. 2024 Jul 19;79(1):286. doi: 10.1093/cid/ciae287]. Clin Infect Dis. Published online October 2, 2023. doi:10.1093/cid/ciad527 Fish DN. Skin and Soft Tissue Infections. In: DiPiro JT, Yee GC, Michael Posey LL, Haines ST, Nolin TD, Ellingrod VL. eds. DiPiro: Pharmacotherapy A Pathophysiologic Approach, 12e. McGraw Hill 3 What antibiotics cover Pseudomonas? 4 What antibiotics cover MRSA? 5 Functions of the Skin Multifunctional organ that contributes to: Temperature regulation Homeostasis/insensible fluid loss Protection against UV light Physical barrier against trauma Sensory perception Immune function Nguyen AV, et al. Int J Mol Sci. 2019;20(8):1811. 6 Anatomy & Physiology Epidermis (outer) Keratinocytes & Langerhans’ cells contribute to immune system Skin microbiome Dermis (middle) Connective tissue, hair follicles, exocrine glands, neurons & blood vessels Subcutaneous/Hypodermis (inner) Adipose tissue, neurons & blood vessels Image available from: https://www.ncbi.nlm.nih.gov/books/NBK470464/ Nguyen AV, et al. Int J Mol Sci. 2019;20(8):1811. 7 Microbiology Skin microbiome Diverse communities of superficial, deep surface, and adherent microbes Dependent on host physiology, environment, immune system, lifestyle Staphylococcus spp. Streptococcus spp. Corynebacterium spp. Eubacterium spp. Propionibacterium spp. Candida spp. (fungi) Malassezia spp. (fungi) Predominant bacterial genera at each skin site Pasternack MS, and Swartz, MN. Cellulitis, Necrotizing Fasciitis, and Subcutaneous Tissue Infections. In: Bennett JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Philadelphia, PA: Elsevier Inc; 2020:1281-1299. 8 Microbiology Skin microbiome Diverse communities of superficial, deep surface, and adherent microbes Dependent on host physiology, environment, immune system, lifestyle Staphylococcus spp. Streptococcus spp. Corynebacterium spp. Eubacterium spp. Propionibacterium spp. Candida spp. (fungi) Malassezia spp. (fungi) Predominant bacterial genera at each skin site Byrd AL, Belkaid Y, Segre. Nat Rev Microbiol. 2018;16(3):143-155. 9 Microbiology Are these gram-positive or gram-negative organisms? Who’s missing? Byrd AL, Belkaid Y, Segre. Nat Rev Microbiol. 2018;16(3):143-155. 10  General Pathophysiology Introduction of Immune Propagation of Clinical Pathogen Response Pathogen Disease Preexisting Innate Dysbiosis Localized vs bacteria Adaptive Structural systemic Introduction Lack changes symptoms of new thereof? and/or Treatment strains? abscess Translocation ? 11 Learning Assessment #1 Which of the following is not a common colonizer of the skin? a. Streptococcus mitis b. Pseudomonas aeruginosa c. Staphylococcus epidermidis d. Candida albicans 12 Infections of the Skin & Soft Tissue (graphic content warning?) SKIN & SOFT TISSUE 13 Stevens DL, et al. Clin Infect Dis. 2014;59(2):e10-e52. Stevens DL, et al. Clin Infect Dis. 2014;59(2):e10-e52. Stevens DL, et al. Clin Infect Dis. 2014;59(2):e10-e52. Stevens DL, et al. Clin Infect Dis. 2014;59(2):e10-e52. General SSTI Treatment Principles Cultures are not useful in non-purulent infections Purulent infections should get incision & drainage (I&D) + cultures Patients with systemic signs of infection should likely receive parenteral abx at least until clinical improvement Febrile (>100.4 degr F) or hypothermic (24 breaths/min HR >90 bpm Leukocytosis (>12 x10^3 cells/μL) or leukopenic (100.4 degr F) or hypothermic (24 breaths/min 4/Severe HR >90 bpm Leukocytosis (>12 x10^3 cells/μL) or leukopenic (