Comparison of 3M BacLite MRSA detection methods with conventional MRSA culture methods.

In the Netherlands the prevalence of MRSA in clinical isolates of
Staphylococcus aureus is with 1.0%, one of the lowest in Europe (1). This low
prevalence is best explained by the national *search and destroy* policy, that
asks for admission screening and isolation of all patients that are at risk of
MRSA carriage (www.wip.nl) . The *at-risk* patients mainly consisted of
patients who have been admitted to and/or treated in foreign hospitals and
people in contact with live pigs and veal calves. The MRSA carriage rates in
these groups are 3.5-5% (3) and 26% respectively (4) . Isolation of these
patients is maintained until the results of screening cultures (nose, throat
and perineal region, and if applicable wounds, urine and sputum) is known.
MRSA screening cultures that are performed in accordance with the national
Dutch guideline (www.nvmm.nl) take between 3-7 days, whereas the 3M BacLite
system takes 5 hrs- 24 hrs to gain a result. In this study two conventional
culture methods are compared with the 3M BacLite system. One method uses a 48
hr incubation in a selective broth, with subsequent subculturing on blood agar.
This is the method currently described by the Dutch Medical Microbiology
society. The second method uses a 24 hr non-selective broth with subculturing
on a commercial chromogenic MRSA agar (MRSA hromID, bioMerieux). These methods
are compared with the 3M BacLite, which is a rapid culture system using a 5 hr
semi-selective broth enrichment with subsequent extraction of S. aureus with
magnetic beads. After extraction and lysis of the bacteria, adenylaat kinase
release is monitored.
Since the majority of patients that have to be isolated and screened is
eventually MRSA negative, having quick and reliable results, decreases the
number of isolation days in the hospital. This is both in the interest of the
hospital and the patient.

To evaluate whether the 3M BacLlte system has a comparable sensitivity and
specificity with the hitherto used conventional culture protocols

Cohort

The burden consists of taking extra set of screening cultures (swabs) from
nose/throat/perineal region and if applicable wounds. There are no risks
associated with this procedure. There is no benefit during the study for the
participating patients.