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Abstract
Background
Asymptomatic vancomycin-resistant enterococci (VRE) colonization precedes infection. VRE-colonized patients serve as silent reservoirs of enterococci that go on to colonize other patients. Rapidly identifying colonized patients is crucial to prevent the spread of VRE. The culture-based method of VRE screening is time-consuming. We evaluated the diagnostic performance of a recently developed multiplex realtime PCR for the detection of VRE.
Methods
We obtained 105 rectal swabs from patients who were being monitored for carriage of VRE. After 24 hour incubation of swabs in enterococcosel broth (EB) supplemented with 6 μg/mL vancomycin, multiplex realtime PCR was performed using the Anyplex TM VanR Real-time Detection (VanR) kit (Seegene, Inc., Seoul, Korea). The results of multiplex realtime PCR were compared to those of culture. We evaluated the specificity and detection limits of multiplex realtime PCR using VanR for VRE.
Results
A total of 96/105 (91.4%) samples were VRE positive according to multiplex realtime PCR with EB while 85/105 (80.9%) samples were positive in culture. Eleven discordant results (10.4%) (multiplex realtime PCR positive, culture negative) were noted. All non-enterococcal bacteria and vancomycin-susceptible enterococci were negative. The DNA detection limits of VanR were 0.035 pg per reaction (3 μL) for Enterococcus faecium and 0.35 pg for Enterococcus faecalis.
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Fig. 1.
Results of multiplex realtime PCR for the detection of VRE in triplicate. (A) E. faecalis (ATCC 29212). (B) E. faecium (BM 4147, vanA). (C) E. faecalis (ATCC 51299, vanB).
Table 1.
Comparative results of multiplex realtime PCR using AnyplexTM VanR Real-time Detection kit and culture method for the detection of VRE
| VRE detection | Multiplex realtime PCR | Total No. (%) of specimens | |
|---|---|---|---|
| Positive | Negative | ||
| Culture | |||
| Positive | 85 (80.9%) | 0 (0%) | 85 (80.9%) |
| Negative | 11 (10.4%)∗ | 9 (8.5%) | 20 (19.1%) |
| Total No. (%) | 96 (91.4%) | 9 (8.5%) | 105 (100%) |
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