Source: Fagan S, Hess D. Skin and soft-tissue infections. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. https://accesspharmacy.mhmedical.com/content.aspx?bookid=1861§ionid=146071658. Accessed February 23, 2019.
TABLE 110-1Predominant Microorganisms of Normal Skin ||Download (.pdf) TABLE 110-1 Predominant Microorganisms of Normal Skin
Micrococci (Micrococcus luteus)
Corynebacterium species (diphtheroids)
Staphylococcus aureus and Streptococcus pyogenes account for the majority of community-acquired SSTIs.
S. aureus is the most common cause of SSTIs in hospitalized patients (30–40% of these being MRSA).
Other nosocomial pathogens include:
Skin serves as a barrier between humans and their environment, functioning as a primary defense mechanism against infections.
Conditions that may predispose a patient to the development of SSTIs include:
High concentrations of bacteria (>105 organisms)
Excessive moisture of the skin
Inadequate blood supply
Availability of bacterial nutrients
Damage to the corneal layer allowing for bacterial penetration
Majority of SSTIs result from disruption of normal host defenses such as
The nature and severity of the infection depend on the type of microorganism and inoculation.
TABLE 110-2Bacterial Classification of Important Skin and Soft-Tissue Infections ||Download (.pdf) TABLE 110-2 Bacterial Classification of Important Skin and Soft-Tissue Infections
|Primary Infections |
|Erysipelas ||Group A streptococci (Streptococcus pyogenes) |
|Impetigo ||Staphylococcus aureus (including methicillin-resistant strains), group A streptococci |
|Lymphangitis ||Group A streptococci; occasionally S. aureus |
|Cellulitis ||Group A streptococci, S. aureus (potentially including methicillin-resistant strains); occasionally other gram-positive cocci, gram-negative bacilli, ...|