• Clinical science

Staphylococcal diseases

Abstract

Staphylococci are gram-positive, spherical-shaped bacteria that form clusters and are commonly found on the skin and mucous membranes. Clinically, the most important species include Staphylococcus aureus and Staphylococcus epidermidis, which are categorized according to their coagulase activity. S. aureus is coagulase positive and expresses several virulence factors which support evasion of the host immune response. S. epidermidis is coagulase negative and is usually less virulent, although it can evade the host immune system by forming and subsequently hiding in a biofilm. S. aureus is commonly responsible for many localized infections (e.g., folliculitis, cervical lymphadenopathy) and also severe organ infections in the setting of bacteremia (e.g., endocarditis, osteomyelitis). As a toxin producer, S. aureus can cause food poisoning (see Staphylococcal food poisoning) and, in severe cases, life-threatening diseases such as staphylococcal scalded skin syndrome (SSSS) or toxic shock syndrome (TSS). Methicillin-resistant S. aureus (MRSA), in particular, poses a major threat to both immunocompromised and multimorbid patients and is a considerable challenge to hospital hygiene. S. epidermidis is mostly responsible for foreign body infections caused by, for example, contaminated peripheral lines or prosthetic joints. The treatment of choice is anti-staphylococcal penicillins (e.g., oxacillin, flucloxacillin) or first and second generation cephalosporins.

Definition

Staphylococci are immotile, gram-positive bacteria that have a round shape and are found in clusters.

Epidemiology

  • S. aureus colonizes approx. 37% of the general human population.
    • Three patterns of carriage have been observed: 20% are permanent carriers, 60% are intermittent carriers, 20% are noncarriers
    • MRSA carrier rates and invasive infections have increased during the last decades.

Epidemiological data refers to the US, unless otherwise specified.

Classification

Resistance and virulence of staphylococci

Staphylococcus aureus

The following factors contribute to the resistance and virulence of S. aureus and allow it to evade the host immune response. For MRSA, see methicillin-resistant .

Staphylococcus epidermidis

Treatment

Staphylococcus aureus

Coagulase-negative staphylococcus (particularly S. epidermidis)

Subtypes and variants

Skin

Ear, nose, and throat

Lymphatic system

Systemic infections

Foreign body infections

Toxin-mediated diseases

Toxic shock syndrome (TSS)

TSS is a systemic inflammatory reaction caused by bacterial exotoxins.

Staphylococcal toxic shock syndrome

Streptococcal toxic shock syndrome

  • Herold G. Internal Medicine. Cologne, Germany: Herold G; 2014.
last updated 07/26/2018
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