Staphylococcus aureus

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Staphylococcus aureus (usually called “staph” for short) is a gram-positive, round-shaped, non-motile bacteria and belongs to the family Staphylo-coccaceae. 1 Staph can cause a wide range of infections which can be serious or fatal. 2 Staph can also produce toxins that cause food poisoning. 3,4 Staph is a serious cause of healthcare associated infections and community associated skin and soft tissue infections. 3 Treatment of staph infection can be challenging as it can become resistant to several antibiotics. 2

Staph is found in 30% of healthy people and animals, and in most cases it cannot cause any diseases. 2,4 Yet, if staph gets into the body through broken skin such as wounds or grazes, it may lead to an infection. 3 Staph can spread through person-to-person contact including direct contact with healthy people who carry staph, an infected wound, and contaminated hands of health care professionals, or by touching contaminated surfaces. 3,5 Food is contaminated by people who carry staph. 4 Unpasteurised milk and cheese products are also a common source of staph. It produces toxins when multiplying in food. Although staph is killed by heat, the toxins are resistant to heat. 4

Anyone can acquire a staph infection. Yet, staph infection is common in people with chronic conditions such as diabetes, cancer, vascular disease, eczema, and lung disease; immunocompromised conditions; or have undergone invasive procedures such as surgery; or have prosthetic device (For example, intravenous catheters, artificial joints, heart valves, and vascular devices). 5

Invasive infections Staph can cause serious infections which may lead to death including bacteraemia (bloodstream infection), pneumonia (lung infection), osteoarticular infection (bone and joint infections), infective endocarditis (infection of the endocardial surface of the heart), and toxic shock syndrome (toxinmediated acute life-threatening illness). 3

Table 1. Suggested treatments for staph infections 3,4,6

Invasive infections

Skin and soft tissue infections

Staphylococcal food poisoning

Healthy people who carry staph Hospitalisation

Prolonged intravenous antibiotic therapy which depends on the specific manifestation and clinical response

Most infections will heal without treatment

Some cases may require incision and drainage of the infected site and antibiotics

Rehydration and other supportive treatments

Antibiotics are not useful

Antibiotics are only required under special circumstances

Skin and soft tissue infections Clinical manifestations vary and can range from benign (Such as pimples, boils, impetigo, and uncomplicated cellulitis) to severe conditions including surgical site infections, cutaneous abscesses, and purulent cellulitis. 3

Food poisoning Symptoms usually develop within 30 minutes to six hours and lasts for only 24 hours. Patients may have vomiting, nausea, stomach cramps, and diarrhoea. Severe illness is rare. 4

Based on the specific clinical manifestation, a staph infection is diagnosed by growing the bacteria from specimens such as pus, blood, stool, or vomitus. Since staph bacteria are becoming resistant to certain antibiotics, antimicrobial susceptibility tests should be used to identify these drug-resistant bacteria including Methicillin-resistant Staph, Vancomycin-intermediate Staph, and Vancomycin-resistant Staph. 5 In food poisoning, although toxins can be detected in foods, the diagnosis is usually based on the clinical symptoms of the patient. 4,6

Staph infection can be treated with appropriate antibiotics such as glycopeptides (Vancomycin and teicoplanin), antistaphylococcal penicillins (Oxacillin and methicillin), or daptomycin. 3 Antimicrobial susceptibility tests are used in case of antibiotic resistance (see Table 1). professionals and good personal hygiene by the infected person. 2,5,6 In hospital settings, drug-resistant staph infected patients should be treated in a designated room. Staff and visitors should follow the hospital’s recommended precautions. 6 Food safety practices must be followed during preparation and storage of food to prevent food contamination. 4

REFERENCES 1. Chowdhury AN, Hossain N, Rahman M,

Ashrafuzzaman. Prevalence of multidrug resistance in human pathogenic Staphylococcus Aureus and their sensitivity to Allamanda cathartica L. leaf extract. International Current Pharmaceutical Journal. 2013;2(11):185-188.

2. Centers for Disease Control and Prevention. Staphylococcus aureus in Healthcare Settings. Healthcare-associated Infections (HAI) 2011 [cited May 2019]. Available from:https://www.cdc.gov/ hai/organisms/staph.html

3. Tong SYC, Davis JS, Eichenberger E, Holland TL, Fowler VG. Staphylococcus aureus Infections: Epidemiology, Pathophysiology, Clinical Manifestations, and Management. Clinical Microbiology Reviews. 2015;28(3):603-661.

4. Centers for Disease Control and Prevention. Staphylococcal Food Poisoning. Food Safety 2018 [cited May 2019]. Available from:https://www.cdc. gov/foodsafety/diseases/staphylococcal.html

5. Centers for Disease Control and Prevention. General Information About MRSA in Healthcare Settings. MRSA 2019 [cited May 2019]. Available from: https://www.cdc.gov/mrsa/healthcare/

6. South Australia Health. Staphylococcus aureus including methicillin-resistant Staphylococcus aureus (MRSA) - including symptoms, treatment and prevention Infectious diseases 2017 [cited May 2019]. Available from: http://www.sahealth. sa.gov.au/