Rapid screening of methicillin-resistant Staphylococcus aureus using PCR and chromogenic agar: a prospective study to evaluate costs and effects

Abstract

Pre-emptive isolation of suspected methicillin-resistant Staphylococcus aureus (MRSA) carriers is considered essential for controlling the spread of MRSA, but noncolonized patients will be isolated unnecessarily as a result of a delay in diagnosis of 3-5 days with conventional cultures. We determined costs per isolation day avoided, and incremental costs of rapid MRSA screening tests when added to conventional screening, but with decisions on isolation measures based on PCR results. A prospective multicentre study evaluating BD GeneOhm MRSA PCR (`IDI') (BD Diagnostics, San Diego, CA, USA), Xpert MRSA (`GeneXpert') (Cepheid, Sunnyvale, CA, USA) and chromogenic agar (MRSA-ID) (bioMérieux, Marcy-l'Etoile, France) was performed in 14 Dutch hospitals. Among 1764 patients at risk, MRSA prevalence was 3.3% (n=59). Duration of isolation was 19.7 and 16.1 h with IDI and GeneXpert, respectively, and would have been 30.0 and 76.2 h when based on chromogenic agar and conventional cultures, respectively. Negative predictive values (at a patient level) were 99.5%, 99.1% and 99.5% for IDI, GeneXpert and chromogenic agar, respectively. Numbers of isolation days were reduced by 60% and 47% with PCR-based and chromogenic agar-based screening, respectively. The cost per test was €56.22 for IDI, €69.62 for GeneXpert and €2.08 for chromogenic agar, and additional costs per extra isolation day were €26.34. Costs per isolation day avoided were €95.77 (IDI) and €125.43 (GeneXpert). PCR-based decision-making added €153.64 (IDI) and €193.84 (GeneXpert) per patient to overall costs and chromogenic testing would have saved €30.79 per patient. Rapid diagnostic testing safely reduces the number of unnecessary isolation days, but only chromogenic screening, and not PCR-based screening, can be considered as cost saving.

Challenging and emerging pathogens in cystic fibrosis

“…Similarly, in adult patients in a uk cf center, the prevalence increased from 1 % in 1985 to 6% in 2005 85 . In the Utrecht cf center, the prevalence of mrsa is very low (Table 1), which is similar to the low prevalence of mrsa in other patients in the Netherlands, where mrsa infection control policies consist of pre-emptive isolation of patients who are considered at high risk of mrsa carriage, until the absence of mrsa is proven 86 .…”

Positive predictive value of the Xpert MRSA assay diagnostic for universal patient screening at hospital admission: influence of the local ecology

“…False-positive PCR results increase the number of patients in unnecessary isolation. Patient isolation is costly and cumbersome for hospital staff and has been associated in some settings with a reduced quality of patient care [30]. In our setting, the low MRSA Only for one of the two strains prevalence (3%) at hospital admission combined with a prevalence of about 3% of MLST CC1 isolates among MSSA carried by Belgian hospitalized patients led to a low PPV of the XP PCR assay.…”

“…This faster detection could, theoretically, shorten the delay in initiating contact isolation precautions for MRSA carriers and, therefore, lead to reduced cross-infection, length of hospital stay, and costs of hospital-acquired infections [28,29]. However, several studies have shown discordant results regarding the cost-effectiveness and effect on MRSA transmission of molecular screening compared with chromogenic cultures [30]. False-positive PCR results increase the number of patients in unnecessary isolation.…”

Rapid molecular detection of extended-spectrum β-lactamase gene variants with a novel ligation-mediated real-time PCR

“…It has been calculated that isolation of a patient means an additional J26.34 each day on a regular ward in a non-outbreak situation (Wassenberg et al, 2010).…”