ABSTRACT
Carbapenemase-producing organisms (CPO) have been identified by global health leaders as an urgent threat. Detection of patients with gastrointestinal carriage of CPO is necessary to interrupt their spread within health care facilities. In this multisite study, we assessed the performance of the Xpert Carba-R test, a rapid real-time quantitative PCR (qPCR) assay that detects five families of carbapenemase genes (blaIMP, blaKPC, blaNDM, blaOXA-48, and blaVIM) directly from rectal swab specimens. Using dual swabs, specimens from 755 patients were collected and tested prospectively. An additional 432 contrived specimens were prepared by seeding well-characterized carbapenem-susceptible and -nonsusceptible strains into a rectal swab matrix and inoculating them onto swabs prior to testing. Antimicrobial susceptibility testing, broth enriched culture, and DNA sequencing were performed by a central laboratory blind to the Xpert Carba-R results. The Xpert Carba-R assay demonstrated a positive percentage of agreement (PPA) between 60 and 100% for four targets (blaKPC, blaNDM, blaVIM, and blaOXA-48) and a negative percentage of agreement (NPA) ranging between 98.9 and 99.9% relative to the reference method (culture and sequencing of any carbapenem-nonsusceptible isolate). There were no prospective blaIMP-positive samples. Contrived specimens demonstrated a PPA between 95 and 100% and an NPA of 100% for all targets. Testing of rectal swabs directly using the Xpert Carba-R assay is effective for rapid detection and identification of CPO from hospitalized patients.
KEYWORDS: Gram-negative bacteria, multidrug resistance, public health, surveillance studies
INTRODUCTION
The rapid dissemination of carbapenemase-producing organisms (CPOs) throughout the world has raised concerns globally. Bacteria harboring these enzymes represent an infection control challenge for health care facilities and have proven to be a major public health threat (1–3).
In the United States, most clinical infections due to CPOs have been attributed to organisms containing the Klebsiella pneumoniae carbapenemase (KPC) or the New Delhi metallo-β-lactamase (NDM) (2). More recently, however, outbreaks due to organisms containing oxacillinase enzymes (e.g., OXA-48) have been reported, particularly in some European countries (4, 5). KPC-containing organisms have reached endemic levels in parts of Europe and Israel (6, 7), and NDM-containing organisms have been recovered throughout the Indian subcontinent (8) from clinical samples as well as from the environment (9). Also problematic in South America, Europe, and Asia are organisms containing the Verona integron metallo-β-lactamase (VIM) and the imipenemase (IMP) family of carbapenemases (10). Sporadic outbreaks of Pseudomonas aeruginosa containing blaVIM have been reported in South America (11, 12) and in Chicago (13). One paper by Barbarini and colleagues described the changing epidemiology of CPOs in an Italian hospital over a 3-year period, in which 44 blaVIM-positive K. pneumoniae isolates were reported (14). Another study reported a single isolate of sequence type 258 (ST258) blaKPC K. pneumoniae that was also found to coexpress blaVIM in addition to other resistance determinants (15). In spite of these limited reports, however, the blaVIM β-lactamase has been reported to a lesser extent than other carbapenemases in species of Enterobacteriaceae.
A prior study described the performance characteristics of a pilot device, the Xpert MDRO assay (Cepheid, Sunnyvale, CA, USA), which detected blaKPC, blaNDM, and blaVIM (16). A modification of this assay, the immediate predicate device to the test evaluated in this study, added blaIMP and blaOXA-48 and was CE-IVD-cleared for use in the European markets (17). According to Tato et al., the revised assay demonstrated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) that were all above 95% (17), but that study and other reports failed to detect blaOXA-181 (18, 19) and blaOXA-232 (20), both of which have emerged as important variants of blaOXA-48 (19, 21).
We hypothesized that a revised Xpert Carba-R test containing additional primers and probes would detect blaOXA-48 variants, such as blaOXA-181 and blaOXA-232. This study was performed as a multicenter, prospective evaluation of the new assay in hospitalized and long-term-care facility patients in the United States and Europe.
RESULTS
Xpert Carba-R assay results with prospective swab specimens and contrived specimens.
A total of 1,187 samples (755 prospective rectal swabs and 432 contrived specimens) were included in the final analysis after excluding ineligible specimens and study protocol deviations. Of the 802 prospective samples initially collected, 17 did not meet eligibility criteria: 1 was a duplicate swab from a previously enrolled patient, 1 was too soiled for testing, 1 was from a patient not hospitalized or residing in a long-term-care facility, and 14 were excluded due to lack of informed consent. For the 785 eligible samples, an additional 30 were excluded from the final analysis: 2 samples were excluded due to deviations in the running of controls on the GeneXpert system, 10 were due to shipping/testing delays between the clinical site and the central laboratory, 16 were excluded because of identification of an intrinsically carbapenem-resistant organism (i.e., Stenotrophomonas maltophilia), and 2 samples had invalid results twice with the Xpert Carba-R test. These invalid results were due to sample processing control (SPC) errors. The SPC ensures that PCR conditions are appropriate for amplification and that no PCR inhibitors are present. Of the 755 rectal swab specimens included in the study for the analysis, 76 (10.1%) contained a carbapenem-nonsusceptible organism that was positive for at least one of the assay targets.
Amplification of at least one target gene occurred in 487/1,187 (41.0%) samples by the Xpert Carba-R assay (Table 1). The Xpert Carba-R assay identified eight samples that contained multiple carbapenemase genes (2 blaKPC and blaOXA-48, 2 blaVIM and blaKPC, 1 blaVIM and blaOXA-48, 1 blaNDM and blaOXA-48, 1 blaVIM and blaNDM, and 1 blaKPC and blaNDM). All positive results were obtained within 50 min of initiating the assay.
TABLE 1.
Overall performance of the Xpert Carba-R assay versus reference method for prospective and contrived samples
| Result by GeneXpert Carba-R | No. of samples by reference methoda: |
||
|---|---|---|---|
| Positive | Negative | Total | |
| Positive | 467 | 20 | 487 |
| Negative | 11 | 689 | 700 |
| Total | 478 | 709 | 1,187 |
Selective culture plus DNA sequence analysis.
Comparison of the Xpert Carba-R to reference culture and DNA sequencing.
In this study, 1,187 specimens (prospective and contrived) were tested on the Xpert Carba-R assay with five targets for a total of 5,935 results.
In total, 1,178/1,187 (99.2%) samples produced a valid result on the first run of the Carba-R assay. There were four invalid results and five errors that occurred on initial testing, but upon retesting, all nine yielded a valid result. A sample was considered positive by the Xpert Carba-R assay if at least one carbapenemase gene was detected. A sample was negative if all of the targets were negative (Table 1). Individual performance characteristics for each target gene, including positive percentage of agreement (PPA) and negative percentage of agreement (NPA), are shown in Table 2 stratified by sample type (prospective versus contrived) (22).
TABLE 2.
Summary of the Xpert Carba-R performance for each carbapenemase target stratified by specimen type
| Sample type (n) | Carbapenemase target | No. of samplesa: |
% of agreement (95% CI)b |
||||
|---|---|---|---|---|---|---|---|
| TP | FP | TN | FN | PPA | NPA | ||
| Prospective (755)c | blaIMP | 0 | 1d | 754 | 0 | NA | 99.9 (99.3–100) |
| blaKPC | 30 | 5e | 720 | 0 | 100 (88.4–100) | 99.3 (98.4–99.8) | |
| blaNDM | 8 | 2f | 745 | 0 | 100 (67.6–100) | 99.7 (99.0–99.9) | |
| blaOXA-48 | 32 | 7g | 715 | 1 | 97.0 (84.2–99.9) | 99.0 (98.0–99.6) | |
| blaVIM | 6 | 8h | 737 | 4 | 60 (31.3–83.2) | 98.9 (97.9–99.5) | |
| Contrived (432) | blaIMP | 76 | 0 | 352 | 4 | 95 (87.8–98) | 100 (98.9–100) |
| blaKPC | 80 | 0 | 352 | 0 | 100 (95.4–100) | 100 (98.9–100) | |
| blaNDM | 80 | 0 | 352 | 0 | 100 (95.4–100) | 100 (98.9–100) | |
| blaOXA-48 | 79 | 0 | 352 | 1 | 98.8 (93.3–99.8) | 100 (98.9–100) | |
| blaVIM | 81 | 0 | 350 | 1 | 98.8 (93.4–99.8) | 100 (98.9–100) | |
TP, true positive; FP, false positive; TN, true negative; FN, false negative.
CI, confidence interval; PPA, positive percentage of agreement; NPA, negative percentage of agreement; NA, not applicable.
Of the 755 prospective rectal swab specimens evaluated in the study, 636 specimens did not yield a culture isolate. From the remaining 119 specimens, 112 carbapenem-nonsusceptible organisms were recovered by the reference culture in addition to 7 carbapenem-susceptible organisms: 5 Pseudomonas aeruginosa, 1 Escherichia coli, and 1 Enterobacter cloacae.
One discrepant specimen was confirmed as FP after analysis.
One of the 6 discrepant specimens was determined to be TP after analysis. The site reported that subject was on ertapenem at the time of specimen collection.
One of the 3 discrepant specimens was determined to be TP after analysis.
Three of the 10 discrepant specimens were determined to be TP after analysis.
Two of the 8 discrepant specimens were determined to be TP after analysis.
From the 755 prospectively collected rectal swabs, 112 carbapenem-nonsusceptible organisms were recovered by the reference culture method. These organisms tested intermediate or resistant to at least one carbapenem by disk diffusion testing.
Resolution of discrepant results with the Carba-R assay.
Eleven samples (five prospective and six contrived) tested negative for all five carbapenemase targets when tested by the Xpert Carba-R assay, but MacConkey broth grew a carbapenem-nonsusceptible isolate that tested positive for one of the five target carbapenemase genes using the reference method. These were classified as Xpert false-negative results. Upon bidirectional sequencing of the MacConkey broth, 4 blaIMP-1, 2 blaOXA-48, and 5 blaVIM samples were identified (Table 2). For the prospective samples, 1 K. pneumoniae isolate carried blaOXA-48 and 4 P. aeruginosa isolates carried blaVIM.
In addition, 25 prospectively collected samples yielded a positive result for one carbapenemase gene that was negative compared to the reference method. Seven of the 25 samples (1 blaKPC [sample 8], 1 blaNDM [sample 7], 3 blaOXA-48 [samples 4, 5, and 9], and 2 blaVIM [samples 15 and 23] were considered true positives after discrepant analyses, which included PCR using alternate primer sets from those in the assay and direct sequencing of the MacConkey broth (Table 3). The remaining 18 samples were considered Xpert false-positive results (Table 3).
TABLE 3.
Discrepant testing results from prospectively collected rectal swabsa
| Sample | Target(s) positive by Carba-R assay | Reference method result |
Discrepant analysis resultb | Outcome | |
|---|---|---|---|---|---|
| Culture | DNA sequencing | ||||
| 1 | blaKPC, blaOXA-48 | K. pneumoniae | No bands on Agilent | Negative | FP |
| 2 | blaVIM, blaKPC | No isolate recovered | NA | NA | FP |
| 3 | blaVIM, blaOXA-48 | K. pneumoniae | blaOXA-48 | blaOXA-48 | FP for blaVIM |
| 4 | blaKPC, blaOXA-48 | K. pneumoniae | blaKPC | blaKPC, blaOXA-48 | TP |
| 5 | blaNDM, blaOXA-48 | K. pneumoniae | blaNDM | blaNDM, blaOXA-48 | TP |
| 6 | blaVIM, blaNDM | No isolate recovered | NA | NA | FP |
| 7 | blaNDM, blaKPC | K. pneumoniae | blaKPC | blaNDM, blaKPC | TP |
| 8 | blaVIM, blaKPC | P. aeruginosa | blaVIM | blaVIM, blaKPC | TP |
| 9 | blaOXA-48 | No isolate recovered | NA | blaOXA-48 | TP |
| 10 | blaVIM | No isolate recovered | NA | NA | FP |
| 11 | blaOXA-48 | No isolate recovered | NA | NA | FP |
| 12 | blaVIM | No isolate recovered | NA | NA | FP |
| 13 | blaOXA-48 | No isolate recovered | NA | NA | FP |
| 14 | blaKPC | No isolate recovered | NA | NA | FP |
| 15 | blaVIM | No isolate recovered | NA | blaVIM | TP |
| 16 | blaVIM | No isolate recovered | NA | NA | FP |
| 17 | blaKPC | No isolate recovered | NA | NA | FP |
| 18 | blaNDM | P. aeruginosa | No bands on Agilent | NA | FP |
| 19 | blaIMP | P. aeruginosa, K. pneumoniae | No bands on Agilent | NA | FP |
| 20 | blaKPC | No isolate recovered | NA | NA | FP |
| 21 | blaOXA-48 | No isolate recovered | NA | NA | FP |
| 22 | blaOXA-48 | No isolate recovered | NA | NA | FP |
| 23 | blaVIM | No isolate recovered | NA | blaVIM | TP |
| 24 | blaOXA-48 | No isolate recovered | NA | NA | FP |
| 25 | blaOXA-48 | No isolate recovered | NA | NA | FP |
NA, not applicable; FP, false positive; TP, true positive.
The discrepant analysis results represent DNA extraction plus sequencing from MacConkey's broth.
Table 2 lists the overall performance of the Xpert Carba-R assay following resolution of discrepant testing results among prospectively collected rectal specimens. One of the 6 discrepant samples for blaKPC was determined to be a true positive for blaKPC, making the total of true positives 31. One of the 3 discrepant results for blaNDM was confirmed as true positive for blaNDM, and 3 of 9 specimens that were discrepant for blaOXA-48 were confirmed to be true positives.
DISCUSSION
Identification of patients that are colonized with CPOs as an aid to infection control is becoming more common, especially in regions with a high prevalence of CPOs, and is recommended by public health organizations, such as the CDC (3). There are multiple methods of screening patients for CPOs, including culture and phenotypic screening methods, use of chromogenic media, and nucleic acid amplification techniques (23). Culture-based methods often have various sensitivities and specificities for detecting CPOs and suffer from long turnaround times. In their review of surveillance methods, Viau and colleagues examined 16 studies that utilized different culture methods for recovery of CPOs (23). They found that sensitivities could range from 42 to 96%, depending on the culture media utilized, and that the limits of detection varied between media and the carbapenemase classes. Phenotypic culture-based confirmatory tests like the modified Hodge test lack specificity, can produce false-negative results with NDM-producing isolates (24), and have been shown to produce false-positive results in extended-spectrum β-lactamase (ESBL) isolates that were carbapenem susceptible (25). Regardless of the culture method employed, they all require overnight incubation, which increases the turnaround time. As such, molecular techniques have been increasingly favored due to rapid turnaround times and both increased sensitivity and specificity. The desire for more rapid results is driven by infection control and prevention strategies aimed at reducing cross-transmission of CPOs, such as requiring contact precautions for colonized patients, dedicated health care personnel, or cohorting patients who are colonized if isolation rooms are not available (3). As recently described by Janelle and colleagues, blaNDM-producing Enterobacteriaceae were identified in community patients (26). This is very concerning because these patients lacked the traditional risk factors.
In this multisite study, we evaluated the performance of the Cepheid Xpert Carba-R assay for detection of carbapenemase genes directly from rectal swabs. We tested 755 prospectively collected rectal swab specimens from patients across five geographic sites and supplemented the results with 432 contrived specimens that included all organisms with at least one of the five carbapenemase gene families. In this study, there were only 5/755 (0.6%) of samples that were falsely negative by the Xpert Carba-R assay compared to the reference method (1 blaOXA-48 and 4 blaVIM). It is possible that a low number of organisms in the specimen was a factor in the failure to amplify the target gene (i.e., the target was below the limit of detection of the assay).
One limitation of the previous Xpert Carba-R assay was the failure to detect clinically relevant variants of blaOXA-48, including blaOXA-181 (18) and blaOXA-232 (20). Based on these early findings and the importance of these blaOXA-48 variants, Cepheid added additional primer and probe sequences to the assay to enable detection of these resistance determinants. Isolates containing blaOXA-181 were detected in contrived specimens with the revised assay. Although no blaOXA-232 isolates were detected in the prospective specimens, blaOXA-232-containing isolates were detected in inclusivity testing studies using reference isolates (27). Other published studies also have reported the ability of the revised assay to detect blaOXA-181 and blaOXA-232 using this version of the Xpert Carba-R assay (28).
One other commercial assay is available for the direct detection of carbapenemase genes, the Check-Direct CPE assay (Checkpoints, Wageningen, Netherlands). This assay detects only four of the five targets of the Xpert Carba-R assay: blaKPC and blaOXA-48 are detected individually, but blaVIM and blaNDM are detected in the same channel (i.e., are not reported separately) on some platforms unless the assay is being run using the BD Max (BD, Franklin Lake, NJ, USA), and blaIMP is not included in the Check-Direct CPE assay. Additionally, the Check-Direct CPE assay has only received CE-IVD clearance for diagnostic testing in European markets. One prospective study evaluated the assay using 301 perirectal swabs, and the authors reported a 79% false-positivity rate (29). However, the lack of a standardized reference method between studies makes comparisons more challenging.
The Xpert Carba-R Assay is the first FDA-cleared assay that can detect blaIMP, blaKPC, blaNDM, blaOXA-48, and blaVIM directly from rectal swabs. This assay has also received FDA clearance for testing pure colonies of carbapenem-nonsusceptible isolates, including members of the Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii. This will have a substantial impact on rapid identification of patients with CPO gastrointestinal colonization or a positive clinical culture within an hour from the time the sample is collected and transported to the clinical microbiology laboratory. In addition, this study demonstrated that carbapenemase genes could be detected for up to 5 days from collection of the rectal swab when the swabs were maintained at a temperature between 2 and 28°C in the original transport container. This could greatly facilitate testing of specimens collected from patients in nonhospital settings, such as long-term-care facilities or nursing homes. Furthermore, in light of the recent report describing the isolation of CPO from community patients without health care exposures (26), the combination of rapid collection and testing directly from a rectal swab is appealing.
In conclusion, the Cepheid Xpert Carba-R assay is a reliable and accurate multiplex, qualitative assay with the ability to detect five families of clinically relevant carbapenem resistance genes directly from rectal swab samples. Direct testing from samples decreases the time to detection of patients with gastrointestinal colonization with CPOs compared to culture-based methods. This will allow clinicians and infection control personnel to make rapid decisions about measures to implement to reduce the transmission of these organisms within health care facilities.
MATERIALS AND METHODS
Study design.
This multicenter study was conducted between June 2015 and January 2016 at three health care facilities in the United States (Rush University Medical Center, Chicago, IL, NorthShore University HealthSystem, Evanston, IL, and Carolinas Healthcare System, Charlotte, NC) and two facilities in Europe (Hospital Universitario Ramün y Cajal—IRYCIS, Madrid, Spain, and IRCCS—Arcispedale Santa Maria Nuova, Reggio Emilia, Italy). Patients eligible for participation had to be admitted to a participating health care facility (acute care hospital or long-term-care facility) and could only be enrolled once. The study underwent ethical review and was approved at each location. Rectal swab specimens (n = 802) were collected from patients using a dual rayon swab (Copan Diagnostics, Murrieta, CA) in liquid Stuart's transport medium. If samples were not tested immediately on the GeneXpert system as described below, they were stored between 2 and 28°C for up to 7 days in the original transport container. To facilitate evaluation of carbapenemase gene targets of lower prevalence, 432 contrived specimens were used to supplement prospectively collected specimens. Contrived specimens included well-characterized carbapenemase-producing (n = 402) and carbapenem-resistant, noncarbapenemase-producing isolates (n = 30). These isolates were seeded onto swabs near the analytical limit of detection (27) and inoculated into a stool matrix that was negative for the gene targets tested for in the assay. Xpert Carba-R testing and bacterial culture to recover resistant organisms were performed as described below.
Reference culture, susceptibility testing, and DNA sequencing.
Prior to testing any specimen, both swabs in the pair were gently twirled together in an attempt to distribute the organisms evenly between swabs in order to reduce bias between the Xpert assay and the reference culture method. Heavily soiled swabs were excluded from the study per the package insert guidelines (27). On the day of the sample collection, one swab of the pair was used to inoculate an 11-ml MacConkey broth tube (Hardy Diagnostics, Santa Maria, CA) containing a 10-μg meropenem disk (BD, Franklin Lakes, NJ, USA). The tube was vortexed for 10 s and incubated for 20 to 24 h at 35°C in ambient air with the cap loosened. The broth was stored at 2 to 8°C prior to being shipped to a central laboratory (Clinical Microbiology Institute, Inc., Wilsonville, OR, USA) for reference culture and antimicrobial susceptibility testing.
The central reference laboratory received the MacConkey broth tubes and tested them for the presence of carbapenem-nonsusceptible organisms by culturing a 100-μl aliquot of the enrichment broth on a MacConkey agar plate (Remel, Lenexa, KS, USA) with a 10-μg meropenem disk placed in the center of the plate prior to overnight incubation at 35°C in ambient air. Organisms growing within a zone diameter of ≤27 mm around the meropenem disk, as described by Lolans et al. (30), underwent bacterial identification and antimicrobial susceptibility testing. Susceptibility testing to confirm carbapenem resistance was performed by the disk diffusion method with ertapenem, imipenem, and meropenem following the Clinical and Laboratory Standards Institute (CLSI) guidelines (31). If the presence of a carbapenem-nonsusceptible organism was confirmed, DNA was extracted and then purified, quantified, and amplified using primers specific to all five target genes. The primer sequences of the reference PCR assays overlap the Xpert sequences and amplify a larger region of the carbapenemase gene. The production of the appropriate size amplification product was confirmed on an Agilent 2100 bioanalyzer (Agilent Technologies, Santa Clara, CA). If bands shown on the bioanalyzer corresponded to the expected size of the amplicon from any of the five target genes detected by the Xpert Carba-R assay, the amplicon for the isolate was sent to an independent laboratory (ACGT, Inc., Wheeling, IL, USA) for reference bidirectional sequencing analysis.
Xpert Carba-R assay.
Testing was performed using the second swab from the dual swab set using the GeneXpert platform (Cepheid, Sunnyvale, CA). The Xpert Carba-R assay is a qualitative, in vitro real-time PCR assay designed to detect five carbapenemase gene families, including blaIMP, blaKPC, blaNDM, blaOXA-48, and blaVIM. Testing was performed at each participating facility according to the manufacturer's recommendations within 7 days from sample collection (27). Briefly, the swab was broken off into a sample reagent vial and vortexed for 10 s. A total of 1.7 ml of the sample was transferred to the Xpert cartridge using a disposable transfer pipette. The cartridge was then loaded onto the GeneXpert system, and the assay was initiated. The instrument is operated through the use of the GeneXpert Dx software (version 4.4; Cepheid) or the Infinity Xpertise software (version 6.1; Cepheid). The discrete, closed system utilizes a syringe and pumps to aspirate and move sample fluid and reagents from the various chambers within the cartridge during all phases of testing. Quality control (QC) consisted of one positive assay control, which was an Escherichia coli strain that contained a plasmid with DNA fragments of all five target gene sequences. The negative control was the same E. coli strain with the same cloning vector that lacked the inserted gene fragments. Five other organisms, each containing a single carbapenemase gene, were used for additional QC as part of the study. Two of the five organisms were used on each day of testing on a rotating basis. Study samples were not tested unless all four QC tests (e.g., positive and negative controls plus two additional control organisms) yielded correct results. Three of the sites in the study also tested contrived samples. The testing of contrived samples was carried out in the same manner as the prospectively collected rectal swabs.
Data analysis, discrepant result resolution, and statistical analysis.
To assess assay performance characteristics, the results of the Xpert Carba-R assay were compared to the results of reference culture plus DNA sequencing results. A positive result given by the Xpert Carba-R assay indicated the presence of at least one of the target carbapenemase genes in the sample. For each of the samples tested, the results for each target gene are reported separately and were compared to the individual results for each carbapenemase gene by the reference method.
Discrepant results were classified as a result obtained using the Xpert Carba-R assay that did not agree with the reference method performed on the same sample. Discrepant analysis was only done on samples in which a positive result for one target was obtained with the Xpert Carba-R assay but a carbapenem-nonsusceptible organism was not recovered in the reference culture. In these cases, DNA was extracted directly from the MacConkey enrichment broth and then amplified by PCR using alternate primer sets for each target gene. For samples that gave a positive result for one of the five targets, bidirectional sequencing was performed on the extracted DNA to confirm the presence of the carbapenemase gene. For the purposes of resolving discrepant data, a positive result from this method was considered a true positive. No discrepant testing was performed for any specimen that was negative for all carbapenemase targets by the Xpert Carba-R assay but demonstrated growth of colonies on the MacConkey agar that yielded a positive result for a target based on results of DNA sequencing.
ACKNOWLEDGMENTS
Members of the Carba-R Study Team include the following: Flavia Brovarone and Giuseppe Russello, IRCCS—Arcispedale Santa Maria Nuova, Reggio Emilia, Italy; Patria Ruiz-Garbajosa, María Garcia-Castillo, and Marta Tato, Servicio de Microbiología, Hospital Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain; Cyndie J. Hobson, Carolinas College of Health Sciences, Charlotte, NC; and Veronica L. Rankin, Carolinas Healthcare System, Charlotte, NC.
The authors wish to acknowledge Mona Patel, Nova Via, and Barbara Acca, employees of Cepheid, for technical support during the study, and Mark McGuire and nursing leadership within Carolinas Healthcare System, including Grace Sotomayor, Janet Handy, Robert Leonhardt, and the clinical nurse leaders of Carolinas Medical Center, for their contributions.
Funding for this study was provided by Cepheid.
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