Staphylococcus aureus are bacteria commonly found on the skin and in the nose of people. Some strains of staphylococci are resistant to the antibiotic methicillin and are known as MRSA. Community acquired strains may be unrelated to hospital MRSA strains.
Many healthy people carry staphylococcal bacteria on their skin or in the anterior nares of the nose. Some strains of staph are resistant to the antibiotic methicillin and other antibiotics; these are known as methicillin resistant Staphylococcus aureus (MRSA). There are some strains of MRSA referred to as Community acquired MRSA (CaMRSA) which tend to spread in community settings. CaMRSA strains are often quite different to MRSA strains associated with hospitals and can cause disease in otherwise healthy people. CaMRSA usually manifests as skin infections such as pimples and boils, impetigo or cellulitis, and more serious infections including osteomyelitis, bacteraemia and pneumonia.
Crowding and frequent skin to skin contact can increase the risk of infection so outbreaks tend to occur in schools, dormitories, military barracks, correctional facilities, and child care centres. People with co-morbidities such as diabetes, with broken skin or dermatitis, or with immune suppression, are also at risk of infection.
CaMRSA should be considered in the differential diagnosis of serious or recurrent skin and soft tissue infections such as skin abscesses and boils. Collect a specimen for culture and antimicrobial susceptibility from patients with boils, wounds, or other sites of infection that warrant antibiotic therapy particularly severe local infections or when in connection with a cluster or outbreak of infection. It is not necessary to collect nasal cultures in patients with suspected CaMRSA infection.
Incision and drainage remains the primary treatment for boils and abscesses. Patients should be told of the importance of keeping wounds clean and covered following incision. Empiric antibiotic therapy may be used in addition according to the severity and progression of infection, presence of systemic illness, patient co-morbidities, inability to drain abscess, or lack of response to initial treatment with incision and drainage alone. The following treatment is recommended by the Therapeutic Guidelines: Antibiotic.
For large or multiple skin infections or with systemic symptoms (while awaiting culture results) use Di(flu)cloxacillin.
For patients who are hypersensitive to penicillin (excluding immediate hypersensitivity), use cephalexin.
For patients with immediate penicillin hypersensitivity, use clindamycin.For CaMRSA skin infections (probable, confirmed, severe or recurring)
For impetigo (commonly caused by Staph, or Streptococcus pyogenes in some communities):
In non-remote community settings, remove crusts 8-hourly using saline or soap and water, or aluminium acetate solution or potassium permanganate solution, and apply a topical cream such as mupirocin 2% topically, 8-hourly for 7 days.
In remote communities where Streptococcus pyogenes is confirmed, or suspected; remove crusts 12-hourly using saline or soap and water, aluminium acetate solution or potassium permanganate solution. Give benzathine penicillin IM as a single dose.
See the Therapeutic Guidelines: Antibiotic for dosage and further information.
Some people can have repeated skin infections, and members of the same household can be affected due to contact with skin or contaminated objects or surfaces. Routinely ask patients with staph infections about other cases of skin and soft tissue infections in household members or other close contacts. It is important to counsel the patient (and provide them with a fact sheet) about prevention measures and good hygiene practices. Encourage the patient to share the fact sheet with their contacts.
Current evidence does not support the routine use of agents to eliminate colonisation. However, it may be reasonable to try and eliminate staph carriage if:
Decolonisation should be considered only where standard prevention measures have proven unsuccessful at interrupting transmission. Key points for a decolonisation procedure include:
CaMRSA is not notifiable in NSW, however, the public health unit should be contacted if a potential outbreak or cluster of infections is identified. A cluster may be considered as two or more cases occurring in a defined group (such as a household or sporting group).
Management of individuals with skin and soft tissue infections
For further information please call your local Public Health Unit on 1300 066 055