Should all patients be screened for MRSA?

Has the time come to actively screen all admission for MRSA (methicillin RESISTANT staph aureus)? A recent study at the VA may suggest that this may be the way to go. The study was conducted across the US where all admissions were screened for MRSA (active surveillance). Based on findings they intervened and were able to show a reduction in the number of MRSA infections in the hospitals.

By screening all admissions they essentially conducted active surveillance.

Active Surveillance

What is it?

The act of screening asymptomatic patients. In the case of MRSA it is with a single nasal swabs sent for rapid PCR assay

Active surveillance identified 90% more than clinical cultures alone

Why should patients be screened for MRSA?

Is there any evidence that screening patients does any good? Most of us are probably colonized anyways. Right?

  1. Unidentified asymptomatic carriers contaminate the environment to the same extent as infected patients (reference 1)
  2. MRSA is picked up on the hands of associates
  3. Potential exposure to new patient
  4. New acquisition
  5. The cycle of spread continues…

So what if more patients get colonized?

Does new acquisition do any harm?

New acquisition of MRSA colonization carries a 30% risk of invasive disease in the next 18 months such as:

  1. Bacteremia
  2. Skin and soft tissue infections

These can be potentially serious complications of any admission.

(Huang et al), (Croft et al), (Pujol et al), (Davis et al)

How common is MRSA in the community?

Do we know how common MRSA colonization really is?

  1. Prevalence in VA admissions (1,700,000) was 13.6%
  2. General US prevalence 1.5%
  3. Non VA hospitals 6.3%
  4. Hospital employees 6.2% – most common assumptions are that all hospital workers are MRSA positive. This is not the case. (Askarian et al) (Johnson et al) (Orisi et al)
  5. At our hospital we have seen a ~6% positive rate among patients attending our joint replacement class. A 12% rate has been seen among our group home population that were screened on admission.

So what can be done?

The VA study

Jain et al conducted a study in the VA system to specifically measure if early identification of asymptomatic MRSA carriers along with preemptive infection control precautions could reduce the number of hospital acquired MRSA infections.

What was done?

1,700,000 screening tests done nation wide in the VA system between 2007 and 2010
96% of all admissions were screened
All positive patients were placed in contact precautions for the duration of admission
Strict hand washing was observed


17% reduction in ICU transmission
21% reduction in non-ICU transmission
Healthcare associated infection rates dropped 62%, from 1.64 per 1000 to 0.62 per 1000
MRSA blood stream infections by 79%, from 0.14 per 1000 to 0.03 per 1000
Pneumonia reduction by 37%, from 0.35 to 0.22 per 1000

What did not improve?

Rates of ventilator associated pneumonia
Rates of central venous catheter MRSA infections


So it looks like early identification and isolation of patients with known MRSA colonization can reduce the environmental contamination with MRSA thereby reducing the number of new acquisitions which eventually reduce the number of new cases admitted with MRSA. The study shows benefit not only in those with known MRSA but in those at risk. But does treating those colonized have any added benefit?

Treating patients colonized with MRSA

Gould et al showed that in addition to screening that daily muprocin along with chlorhexidine body washes can have a beneficial effect.

What was done

  1. Screening on admission
  2. Positive patients placed in contact precautions
  3. Mupirocin, intranasally
  4. Chlorhexidine daily baths

The result

New MRSA cases dropped from 16% of admissions to 6%
Treatment of 11 colonized patients appears to reduce 1 clinical case
Length of stay decreased

Are there any other advantages to early identification of colonized patients?

Isolate in a timely manner: Isolating early in the admission can reduce stress for the patient and family. One of the worst things for family to see is that their loved one who walked into the hospital is suddenly a week later in contact precautions. It sends a very negative message of slow identification of the medical issues. Plus it projects a perception that the patient is sicker than before isolation.
Reduce environmental contamination: By early isolation the risk of environmental contamination is reduced. Thereby reducing risk of spread to other patients. As shown by Boyce et al
Improve patient satisfaction: By correctly identifying who is positive on admission it can clarify where the the acquisition did not occur.
Delivery of a consistent message: By not moving patients in and out of isolation, families are less confused about their loved ones medical problems.
Optimize peri-operative antibiotic prophylaxis: Use of vancomycin in some cases for perioperative prophylaxis may be appropriate without falling out of SCIP guidleines.
Validate nosocomial acquisition rates: Nosocomial acquisition rates are among the quality benchmarks that are measured and show up on the hospital report card. They will have bearing on future hospital reimbursement. Early screening may allow a better measurement of what is and what is not hospital acquired. Remember only patients that are positive for MRSA 48 hours after admission are considered hospital acquired and will show up on statistics.


There is not set standard for decolonization. I am not sure that I even like to use the term decolonization which implies an absolute removal of all organisms. These measures are merely reducing the total organisms for a short period of time (perhaps months) to create a window of reduced colonization burden. Perhaps “colonization managment” is a better term.

Most physicians would recommend:

  1. Intranasal mupirocin: Apply a small amount to each nostril, usually in the morning and evening, Then gently squeeze your nostrils together and release. Repeat this for about 1 minute to spread the ointment
  2. Hibaclens: topical use. See instructions for patients

Why not just recommend colonization management for everyone?

As great as it sounds it just does not work long term. The benefit appears to be best for short term use. The idea is to create a “window” in which the colonization concentration is the lowest in order to perform surgery or maintain central lines. The goal is therefore not to eliminate all germs but to reduce the risk of infection at times when the risk is high (illness, surgery etc.).

Other issues with bypassing screening include:

  • Decolonization is a misnomer, it does not reduce ALL it just reduces the number to a manageable number.
  • Blanket decolonization therefore does not remove the need for contact precautions when hospitalized. Environmental contamination will still occur.
  • It does not provide any information on optimizing perioperative prophylaxis.
  • It does not provide any information with regards to nosocomial acquisition that are being tracked by CMS.

Is screening worth the cost?

Nyman et al were able to show a cost benefit to screening.


The point of screening more patients is not to reduce the number of infections in patients that are already colonized. But to reduce the environmental contamination that increases risk of new acquisition that raises risk for future invasive infections in all patients regardless of MRSA colonization status.

The time may be coming where actively screening all admissions may become standard practice to improve patient outcomes, patient safety and satisfaction at a reasonable cost.


  1. Chang, Shelley, Ajay K Sethi, Brittany C Eckstein, Usha Stiefel, Jennifer L Cadnum, and Curtis J Donskey. 2009. Skin and environmental contamination with methicillin-resistant Staphylococcus aureus among carriers identified clinically versus through active surveillance. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 48, no. 10 (May 15): 1423–8. doi:10.1086/598505. .

  2. Huang, Susan S, and Richard Platt. 2003. Risk of methicillin-resistant Staphylococcus aureus infection after previous infection or colonization. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 36, no. 3 (March 1): 281–5. doi:10.1086/345955.

  3. Croft, Chasen A, Vicente A Mejia, Donald E Barker, Robert A Maxwell, Benjamin W Dart, Philip W Smith, and R Phillip Burns. 2009. Methicillin-resistant Staphylococcus aureus in a trauma population: does colonization predict infection? The American surgeon 75, no. 6 (June): 458–61; discussion 461–2.

  4. Pujol, M, C Pena, R Pallares, J Ayats, J Ariza, and F Gudiol. 1994. Risk factors for nosocomial bacteremia due to methicillin-resistant Staphylococcus aureus. European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology 13, no. 1 (January): 96–102.

  5. Davis, Kepler a, Justin J Stewart, Helen K Crouch, Christopher E Florez, and Duane R Hospenthal. 2004. Methicillin-resistant Staphylococcus aureus (MRSA) nares colonization at hospital admission and its effect on subsequent MRSA infection. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 39, no. 6 (September 15): 776–82. doi:10.1086/422997.

  6. Jain, Rajiv, Stephen M Kralovic, Martin E Evans, Meredith Ambrose, Loretta a Simbartl, D Scott Obrosky, Marta L Render, et al. 2011. Veterans Affairs initiative to prevent methicillin-resistant Staphylococcus aureus infections. The New England journal of medicine 364, no. 15 (April): 1419–30. doi:10.1056/NEJMoa1007474.

  7. Gould, Ian M, Fiona M MacKenzie, Graeme MacLennan, Diane Pacitti, Emma J Watson, and David W Noble. 2007. Topical antimicrobials in combination with admission screening and barrier precautions to control endemic methicillin-resistant Staphylococcus aureus in an Intensive Care Unit. International journal of antimicrobial agents 29, no. 5 (May): 536–43. doi:10.1016/j.ijantimicag.2006.12.019.

  8. Boyce, J M, G Potter-Bynoe, C Chenevert, and T King. 1997. Environmental contamination due to methicillin-resistant Staphylococcus aureus: possible infection control implications. Infection control and hospital epidemiology : the official journal of the Society of Hospital Epidemiologists of America 18, no. 9 (September): 622–7.

  9. Robicsek, Ari, Jennifer L Beaumont, Richard B Thomson, Geetha Govindarajan, and Lance R Peterson. 2009. Topical therapy for methicillin-resistant Staphylococcus aureus colonization: impact on infection risk. Infection control and hospital epidemiology : the official journal of the Society of Hospital Epidemiologists of America 30, no. 7 (July): 623–32. doi:10.1086/597550.

  10. Nyman, John A, Christine H Lees, Lindsay A Bockstedt, Gregory A Filice, Catherine Lexau, Lindsey J Lesher, Kathryn Como-Sabetti, and Ruth Lynfield. 2011. Cost of screening intensive care unit patients for methicillin-resistant Staphylococcus aureus in hospitals. American journal of infection control 39, no. 1 (February): 27–34. doi:10.1016/j.ajic.2010.09.006.

  11. Askarian, Mehrdad, Alihosein Zeinalzadeh, Aziz Japoni, Abdolvahab Alborzi, and Ziad A Memish. 2009. Prevalence of nasal carriage of methicillin-resistant Staphylococcus aureus and its antibiotic susceptibility pattern in healthcare workers at Namazi Hospital, Shiraz, Iran. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases 13, no. 5 (September): e241–7. doi:10.1016/j.ijid.2008.11.026.

  12. Johnston, Cecilia P, Amy K Stokes, Tracy Ross, Mian Cai, Karen C Carroll, Sara E Cosgrove, and Trish M Perl. 2007. Staphylococcus aureus colonization among healthcare workers at a tertiary care hospital. Infection control and hospital epidemiology : the official journal of the Society of Hospital Epidemiologists of America 28, no. 12 (December): 1404–7. doi:10.1086/523865.

  13. Orsi, G B, R Marrone, F Ferraro, F Tavella, and A Colosi. Low colonization with MRSA among health-care workers in an Italian hospital. Annali di igiene : medicina preventiva e di comunitĂ  20, no. 5: 503–8.

One thought on “Should all patients be screened for MRSA?

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.