Where S. aureus Lives?

What is Staphylococcus aureus?
Lab tests for staph  

S. aureus lives in:

• healthy people (S. aureus carriers): in the mucosa of the nose, less commonly in the throat, vagina, intestines and lungs; on the skin: mainly in the armpits, under the breasts, and in the groin;
• infected people: in skin lesions, blood, stool, urine, respiratory mucosa, genitals, abscesses of internal organs;
• animals: in pets (fur, skin, nares) and farm animals (cows udders, horses, poultry);
• contaminated food: milk (from infected cow), food prepared and kept outside refrigerator (contamination from infected food worker);
• athletic equipment, toys, workout surfaces;
• air, water, soil, dust (less important sources).

Staph Reservoir

Primary reservoir for S. aureus (including MRSA) is a human. Staph is common in cows (mastitis), poultry, and pets (dogs, cats). In Canada they’ve found MRSA in pigs (1).

How is Staph Infection Spread

Staph may spread from one skin location to another (auto-infection), e.g. by picking the nose followed by scratching the skin, or by clothes. Person to person spread is possible via skin-on-skin contact, or with sharing toys, towels, sport equipment, public showers, sauna, or swimming pools. Infection may also be spread by healthy staph carriers, especially by health personnel. Staph may spread from human to dogs or other pets and then back to the human (2). S. aureus may be found on the skin, hair, nostrils or saliva of dogs. Severe staph endocarditis was reported after a minor dog bite (3). Infection by milking a cow with staph mastitis is possible (4). Staph food poisoning may occur after ingesting food contaminated with staphylococci, released from an infected food worker.

Entry points of staph infection are:

• skin: a hair follicle during minor shaving trauma or depilation, acne, eczema (psoriasis, atopic dermatitis), skin injury, burns, injection, piercing and tattoo punctures, vascular and urinary catheters, surgical wounds;
• respiratory tract: staphylococcal pneumonia may be a complication of influenza or aspiration.

continue reading Staph Epidemiology

Staphylococcus aureus

Staphylococcus aureus (Greek staphyle = bunch of grapes, Latin coccus = spherical bacterium, aureus = golden), or golden staph (pronounced ’staff’), is the most common staphylococcus species causing infections in human.

Lab Tests for Staph
Staph Epidemiology

Staph Infections

S. aureus lives as the part of the normal skin flora in the nose or on the skin in 20-30% of healthy people (staph carriers), (1). However, in even slightly injured skin or mucosa, staph may cause styes, pimples, folliculitis, furuncles, boils (picture 1), swimmer’s ear, sinusitis, epiglotitis, whitlow, breast infection, impetigo, cellulitis, genital infection, or scalded skin syndrome. Infections of internal organs include urinary tract infections, arthritis, pneumonia, infection of veins (thrombophlebitis), lymph nodes (lymphadenitis) or lymph vessels (lymphangitis), bone infection (osteomyelitis) (picture 2), or life threatening  sepsis (staph blood invasion), infection of heart valves (endocarditis),  meningitis, “flesh eating bacteria” infection (necrotizing fasciitis), and toxic shock syndrome. S. aureus enterotoxins may cause food poisoning.

S. aureus and S. epidermidis are among the most common causes of hospital-acquired infections like bloodstream infections, infections of surgical wounds, or pneumonia (2). Staph may also appear in vascular and urinary catheters, prosthetic joints, and heart valves.

Staph skin infection usually appears as a red, warm, painful swelling with a blister, ulcer, or crust, and a drainage (picture 1). Infection may spread into deeper tissues, like bones (picture 2).

Picture 1. A boil on the upper arm	Picture 2. X-ray of child’s legs: osteomyelitis in shin bones (grey patches)

continue reading What is Staphylococcus Aureus?