Answer to Q2

It is well proven that no single anatomic site sampling will detect all MRSA-colonised persons, and sampling anterior nares alone has a highly variable sensitivity (48%-93%). Sampling from ≥1 additional anatomic sites (throat and/or perineum in studies on adults) increases the sensitivity to >90%.

Screening patients

The following anatomic sites should be sampled:

• Adults and children: nasal swab (high nasal swabbing of anterior nares), groin or perineum swab, and throat swab
• Neonates: nasal swab (high nasal swabbing of anterior nares), throat swab, and umbilical swab

Multiple swabs may be used for the above areas, and pooled into a single culture in order to manage costs. When multiple sample site swabs are pooled into a single culture, it isn’t possible to determine precisely which site was positive; however, it is of little concern since the decolonisation regimen is standard and not determined by specific site-positivity.
All patients with active skin lesions and wounds must have separate samples/swabs collected from such sites.

Additionally, consider exit-site swabs for patients with the following devices:

• Tracheostomy (exit site)
• Colostomy (exit site)
• Percutaneous Endoscopic Gastrostomy (PEG)

Screening healthcare workers

Care is needed to distinguish between transient carriage (i.e. nasal carriage which is lost within a day or so of removal from contact with MRSA-positive patients and carries little risk of onward transmission) and prolonged carriage (especially that associated with skin lesions and throat colonisation). This is usually best achieved by screening staff as they come on duty at the beginning of their shift and not as they leave at the end of their shift. In an outbreak setting: nurses, doctors, physiotherapists, other allied health professionals and non-clinical support staff (e.g. porters) should be considered for screening. The special difficulties and risks posed by agency staff should be considered. There is no evidence to suggest that anatomic screening sites should be different from those sampled in patients for MRSA-colonisation screening, and it is recommended to collect a nasal swab (high nasal swabbing of anterior nares), groin or perineum swab, and throat swab.

Question 3 - What is the recommended decolonisation therapy regimen for MRSA-colonised persons?

Answer to Q4

1. Isolation of MRSA-infected or MRSA-colonised patients

• Place patients in a single/private/isolation room when available.
• Cohorting of MRSA patients is acceptable when a single/private/isolation room is not available.

2. Contact precautions

• Don gown and gloves on entry into the patient’s room/cohort area, and remove gown and gloves before exiting the room/cohort area.

3. Dedicated noncritical patient care items
Dedicate noncritical patient care items (e.g. blood pressure cuffs, stethoscopes) to a single patient known to be colonised/infected with MRSA. When equipment must be shared among patients, clean and disinfect the equipment between patients.

4. Cleaning and disinfection

• Develop written protocols for daily and terminal cleaning and disinfection of patient rooms. Protocols should address the type of equipment or surface, persons responsible for performing the tasks, frequency, disinfectant product appropriate to the device or surface and required contact time to achieve effective disinfection.
• Pay close attention to cleaning and disinfection of high-touch surfaces in patient care areas (e.g. bed rails, trolleys/carts, doorknobs, and tap handles).
Disinfect portable, reusable healthcare equipment after each use.

5. Educate patients’ visitors about MRSA: provide information about MRSA and contact precautions

6. Decolonisation therapy should be given. In this particular scenario where all MRSA-infected/colonised patients are neonates, intranasal mupirocin is indicated; however, given the concerns regarding the use of chlorhexidine-containing products in this age group, the clinician concerned must carefully weigh the potential benefit in preventing adverse MRSA related-outcomes versus the risks on a case-by-case basis.

Question 5 - How do you determine whether a healthcare worker is the source of MRSA transmission in an outbreak?

Answer to Q6

There are no controlled studies that examine the specific impact of isolated interventions on interrupting MRSA transmission from colonised healthcare workers to patients; therefore, there are unfortunately no evidence-based recommendations for the management of MRSA-colonised healthcare workers who have been associated with ongoing MRSA transmission to patients.

Interventions that may be considered include the following:

1. Evaluate the MRSA-colonised healthcare worker’s infection prevention practices for opportunities for education and improvement.
2. Ensure appropriate investigation for and treatment of active MRSA infection. In particular, skin infections and sinusitis have been associated with persistent MRSA colonisation in healthcare workers.
3. Decolonisation therapy for healthcare workers with persistent MRSA colonisation – in particular those with skin lesions and throat carriage
4. Work restrictions have been used as a part of outbreak management in some (but not all) scenarios where MRSA-colonised healthcare workers have been associated with transmission of MRSA to patients.
5. Work restrictions include approaches such as leave, restriction from patient care activities, and temporary reassignment to low-risk tasks or units.
6. Healthcare workers colonised with MRSA who work in a high-risk unit/area (e.g. ICU, NICU) generally represent a greater potential risk to patients than healthcare workers working in, for example, an outpatient department. Therefore, work restrictions may be more important for MRSA-colonised healthcare workers in high-risk unit/areas (e.g. NICU, ICU).
7. Staff members with colonised/infected hand lesions should be off work while receiving antimicrobial and decolonisation therapy.
8. It is recommended that a minimum of three screens at weekly intervals (while not receiving antimicrobial therapy) should be performed before a previously positive staff member can be considered to be clear of MRSA.

Discussion

Infants in the NICU are at increased risk for infection and colonisation with MRSA, often resulting in poor outcomes and long-term sequelae. MRSA in the NICU may be acquired from colonised parents, healthcare workers, and other neonates. A substantial proportion of colonised patients will subsequently develop an MRSA infection (e.g. pneumonia, skin/soft tissue infection, primary bloodstream infection). Risk factors for MRSA colonisation include severe underlying illness or comorbid conditions, prolonged hospital stay, exposure to broad-spectrum antimicrobials, presence of invasive devices (such as central venous catheters), and frequent contact with healthcare workers. MRSA cases in the NICU need urgent assessment, rapid investigation, and timeous implementation of infection prevention and control measures in order to prevent outbreaks in this high-risk setting.