Efficiency of the Cepheid Xpert vanA/vanB assay for screening of colonization with vancomycin-resistant enterococci during hospital outbreak

Żabicka, Dorota; Strzelecki, J.; Woźniak, Agnieszka; Strzelecki, Paweł; Sadowy, Ewa; Kuch, Alicja; Hryniewicz, Waleria

doi:10.1007/s10482-011-9681-z

Cited by 21 publications

(17 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These differences may explain the variations in the observed sensitivity, specificity, PPV, and NPV between the two studies. Two additional studies evaluating the performance of the Xpert vanA showed remarkably lower sensitivity by the assay than by culture (11,23). The limited number of specimens tested (Յ50), as well as the use of stool specimens rather than rectal swabs, might explain the suboptimal performance of the Xpert vanA assay in those studies.…”

Section: Discussionmentioning

confidence: 99%

Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci

Babady¹,

Gilhuley²,

Cianciminio-Bordelon³

et al. 2012

J Clin Microbiol

View full text Add to dashboard Cite

We compared the performance characteristics of culture and the Cepheid Xpert vanA assay for routine surveillance of vancomycin-resistant enterococci (VRE) from rectal swabs in patients at high risk for VRE carriage. The Cepheid Xpert vanA assay had a limit of detection of 100 CFU/ml and correctly detected 101 well-characterized clinical VRE isolates with no cross-reactivity in 27 non-VRE and related culture isolates. The clinical sensitivity, specificity, positive predictive value, and negative predictive value of the Xpert vanA PCR assay were 100%, 96.9%, 91.3%, and 100%, respectively, when tested on 300 consecutively collected rectal swabs. This assay provides excellent predictive values for prompt identification of VRE-colonized patients in hospitals with relatively high rates of VRE carriage. Vancomycin-resistant enterococci (VRE) are recognized as nosocomial pathogens alongside methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. Vancomycin resistance in enterococci species is conferred mainly by the presence of the vanA or vanB gene, although the presence of other genes, including vanC, vanD, vanE, and vanG, can also result in a resistant phenotype (7,25). In North America, the vanA gene is the most prevalent resistance marker in enterococci species, followed by the vanB gene, which can be found in bacteria other than enterococci (4, 10). Both the vanA and vanB genes are carried on transposable plasmids, and transfer of these plasmids to other enterococci and S. aureus has been shown both in vitro and in vivo (7).Several reports have shown that in allogeneic hematopoietic stem cell transplant recipients, VRE colonization, prior to stem cell transplantation, is a significant risk factor for the development of VRE bacteremia, which is associated with poor clinical outcomes (3,14,22,24). In order to decrease the spread of VRE in hospital settings, the Hospital Infection Control Practices Advisory Committee (HICPAC) recommends a multipronged approach that includes rapid identification and reporting of VRE-positive stools or rectal swabs by the microbiology laboratory in order to ensure prompt isolation of colonized patients (2).Currently, VRE surveillance is performed at our institution using traditional culture. This procedure requires 48 to 96 h to obtain a final result and involves multiple media and incubation steps. Recently, the Food and Drug Administration (FDA) approved a rapid molecular assay, the Xpert vanA (Cepheid, Sunnyvale, CA), for the detection of VRE directly from rectal swab specimens only. The assay is a real-time, one-step PCR assay performed on the GeneXpert instrument and provides results in less than 1 h, compared to 48 to 96 h with culture. In addition to providing rapid results for timely isolation of colonized patients, rapid and more sensitive detection of VRE may also result in the timely identification of patients at risk for the development of VRE bacteremia. The objective of the present study was to evaluate the performance characteristics of this novel P...

show abstract

Section: Discussionmentioning

confidence: 99%

Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci

Babady¹,

Gilhuley²,

Cianciminio-Bordelon³

et al. 2012

J Clin Microbiol

View full text Add to dashboard Cite

show abstract

“…The Gene Xpert vanA/vanB assay has improved sensitivity compared to direct cultures; therefore, labor-intensive broth-enrichment is not required (10). However, the results of GeneXpert vanA/vanB have a very low PPV and should be confirmed by culture, especially the vanB gene (23). The possible explanations for the false-positive reactions for vanB were lack of specificity of primers/probes of the PCR assay or the presence of van genes in uncultured bacteria (12).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of GeneXpert vanA/vanB assay for the detection of vancomycin-resistant enterococci in patients newly admitted to intensive care units

Yağci¹,

Hatipoğlu²,

Altun³

et al. 2013

Turk J Med Sci

View full text Add to dashboard Cite

The automated Cepheid GeneXpert system provides rapid PCR results and can be used for the identification of VRE. We aimed to evaluate the use of the Cepheid Xpert vanA/vanB real-time PCR assay for the detection of VRE from rectal swabs of patients newly admitted to intensive care units in a hospital setting. Materials and methods:Rectal swab samples of patients newly admitted to 6 intensive care units from March 2011 to February 2012 were obtained. The specimens were analyzed by the GeneXpert system. The results were reported for both vanA and vanB as negative or positive.Results: Comparing the number of inpatients, most of the samples were delivered from the neurosurgery (48.3%), pediatrics (33.3%), and neonatology (20.6%) intensive care units. The positive samples according to GeneXpert vanA/vanB method were 33 (7.3%) among 454 rectal samples. Of these positive samples 22 (4.9%) were vanA, 10 (2.2%) were vanB, and 1 sample (0.2%) was vanA and vanBharboring, by PCR. Conclusion:As a rapid, easy to use, and labor-saving method GeneXpert vanA/vanB can detect VRE-positive patients, particularly in risk groups, as soon as they are admitted to hospital so that infection control policies can be applied immediately.

show abstract

“…As part of the infection control measures that have to be taken by the hospital, especially during outbreaks, these time-consuming methods have a high economic impact (3). Several studies evaluated PCR-based methods for rapid detection of VRE, including the Cepheid Xpert vanA/vanB assay (4)(5)(6)(7). This assay runs on the Cepheid GeneXpert system, a fully automated processor that combines DNA extraction, real-time PCR amplification, and detection, providing results within an hour.…”

mentioning

confidence: 99%

Evaluation of the Xpert vanA / vanB Assay Using Enriched Inoculated Broths for Direct Detection of vanB Vancomycin-Resistant Enterococci

et al. 2014

View full text Add to dashboard Cite

Rapid and accurate detection of VRE (vancomycin-resistant enterococci) is required for adequate antimicrobial treatment and infection prevention measures. Previous studies using PCR for the detection of VRE, including Cepheid's Xpert vanA/vanB assay, reported accurate detection of vanA VRE; however, many false-positive results were found for vanB VRE. This is mainly due to nonenterococcal vanB genes, which can be found in the gut flora. Our goal was to optimize the rapid and accurate detection of vanB VRE and to improve the positive predictive value (PPV) by limiting false-positive results. We evaluated the use of the Xpert vanA/vanB assay on rectal swabs and on enriched inoculated broths for the detection of vanB VRE. By adjusting the cycle threshold (C T ) cutoff value to <25 for positivity by PCR on enriched broths, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 96.9%, 100%, 100%, and 99.5% for vanB VRE, respectively. As shown in this study, C T values of <25 acquired from enriched broths can be considered true positive. For broths with C T values between 25 and 30, we recommend confirming the results by culture. C T values of >30 appeared to be true negative. In conclusion, this study shows that the Cepheid's Xpert vanA/vanB assay performed on enriched inoculated broths with an adjusted cutoff C T value is a useful and rapid tool for the detection of vanB VRE.

show abstract

Efficiency of the Cepheid Xpert vanA/vanB assay for screening of colonization with vancomycin-resistant enterococci during hospital outbreak

Cited by 21 publications

References 18 publications

Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci

Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci

Evaluation of GeneXpert vanA/vanB assay for the detection of vancomycin-resistant enterococci in patients newly admitted to intensive care units

Evaluation of the Xpert vanA / vanB Assay Using Enriched Inoculated Broths for Direct Detection of vanB Vancomycin-Resistant Enterococci

Contact Info

Product

Resources

About