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van Belkum A, Rochas O. Laboratory-Based and Point-of-Care Testing for MSSA/MRSA Detection in the Age of Whole Genome Sequencing. Front Microbiol 2018; 9:1437. [PMID: 30008711 PMCID: PMC6034072 DOI: 10.3389/fmicb.2018.01437] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 06/11/2018] [Indexed: 12/28/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen of animals and humans that is capable of both colonizing and infecting its eukaryotic host. It is frequently detected in the clinical microbiology routine laboratory. S. aureus is capable of acquiring antibiotic resistance traits with ease and, given its rapid global dissemination, resistance to meticillin in S. aureus has received extensive coverage in the popular and medical press. The detection of meticillin-resistant versus meticillin-susceptible S. aureus (MRSA and MSSA) is of significant clinical importance. Detection of meticillin resistance is relatively straightforward since it is defined by a single determinant, penicillin-binding protein 2a', which exists in a limited number of genetic variants carried on various Staphylococcal Cassette Chromosomes mec. Diagnosis of MRSA and MSSA has evolved significantly over the past decades and there has been a strong shift from culture-based, phenotypic methods toward molecular detection, especially given the close correlation between the presence of the mec genes and phenotypic resistance. This brief review summarizes the current state of affairs concerning the mostly polymerase chain reaction-mediated detection of MRSA and MSSA in either the classical laboratory setting or at the point of care. The potential diagnostic impact of the currently emerging whole genome sequencing (WGS) technology will be discussed against a background of diagnostic, surveillance, and infection control parameters. Adequate detection of MSSA and MRSA is at the basis of any subsequent, more generic antibiotic susceptibility testing, epidemiological characterization, and detection of virulence factors, whether performed with classical technology or WGS analyses.
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Affiliation(s)
- Alex van Belkum
- Data Analytics Unit, bioMérieux, La Balme-les-Grottes, France
| | - Olivier Rochas
- Strategic Intelligence, Business Development Direction, bioMérieux, Marcy-l'Étoile, France
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Methicillin-Resistant Staphylococcus aureus Control in the 21st Century: Laboratory Involvement Affecting Disease Impact and Economic Benefit from Large Population Studies. J Clin Microbiol 2016; 54:2647-2654. [PMID: 27307459 DOI: 10.1128/jcm.00698-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection is a global health care problem. Large studies (e.g., >25,000 patients) show that active surveillance testing (AST) followed by contact precautions for positive patients is an effective approach for MRSA disease control. With this approach, the clinical laboratory will be asked to select what AST method(s) to use and to provide data monitoring outcomes of the infection prevention interventions. This minireview summarizes evidence for MRSA disease control, reviews the involvement of the laboratory, and provides examples of how to undertake a program cost analysis. Health care organizations with total MRSA clinical infections of >0.3/1,000 patient days or bloodstream infections of >0.03/1,000 patient days should implement a MRSA control plan.
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Evaluation of the BD Max StaphSR Assay for Rapid Identification of Staphylococcus aureus and Methicillin-Resistant S. aureus in Positive Blood Culture Broths. J Clin Microbiol 2015; 53:3630-2. [PMID: 26292311 DOI: 10.1128/jcm.01922-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/15/2015] [Indexed: 12/14/2022] Open
Abstract
We evaluated the performance of the BD Max StaphSR assay for the direct detection of Staphylococcus aureus from blood culture medium. In a two-center trial, 155 blood cultures from the BD Bactec FX system and 212 from the bioMérieux BacT/Alert system were tested; 170 bottles yielded S. aureus, and all were identified correctly by the BD Max StaphSR assay. The assay required approximately 2.5 h, thus allowing rapid identification of blood cultures flagged positive.
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Evaluation of BD Max StaphSR and BD Max MRSAXT Assays Using ESwab-Collected Specimens. J Clin Microbiol 2015; 53:2525-9. [PMID: 26019193 DOI: 10.1128/jcm.00970-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 05/20/2015] [Indexed: 12/13/2022] Open
Abstract
The BD Max MRSAXT and the BD Max StaphSR assays were validated for the detection of methicillin-resistant Staphylococcus aureus (MRSA) in ESwab samples. In addition, the BD Max StaphSR assay was evaluated for its ability to detect and differentiate S. aureus and MRSA in the same sample. A total of 255 ESwab samples collected from the anterior nares of patients were tested by each of three BD Max assays, including the BD Max MRSA first-generation assay. The results were compared to those of direct and enrichment culture. Additionally, a challenge panel comprising 14 control strains was evaluated to determine the ability of these assays to correctly identify MRSA and also appropriately differentiate S. aureus by the BD Max StaphSR assay. Out of 255 clinical samples tested, 161 were negative and 30 were positive for MRSA, and 45 were positive for S. aureus (by BD Max StaphSR) and negative for MRSA by all three PCR assays and culture. Nineteen samples had discrepant results; all of them were retested by additional laboratory testing. All strains from the challenge panel were correctly identified or excluded by the BD Max MRSAXT and BD Max StaphSR assays. The results showed that the BD Max StaphSR and the BD MRSAXT assays have excellent sensitivity (94.3%) and specificity (97.7%) for detecting MRSA. The BD Max StaphSR assay demonstrated excellent sensitivity (96.4%) and specificity (93.6%) for detecting S. aureus.
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Brukner I, Longtin Y, Oughton M, Forgetta V, Dascal A. Assay for estimating total bacterial load: relative qPCR normalisation of bacterial load with associated clinical implications. Diagn Microbiol Infect Dis 2015; 83:1-6. [PMID: 26008123 DOI: 10.1016/j.diagmicrobio.2015.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/03/2015] [Accepted: 04/20/2015] [Indexed: 12/26/2022]
Abstract
Relative microorganism abundance is a parameter describing biodiversity, referring to how common a bacterial species is within the total bacterial flora. Anal, rectal, skin, mucal, and respiratory swabs are typical clinical samples where knowledge of relative bacterial abundance might make distinction between asymptomatic carriers and symptomatic cases. Assays trying to measure total bacterial load are usually based on the amplification of universal segments of 16S rRNA genes. Previous assays were not adoptable to "direct" PCR protocols, and/or they were not compatible with hydrolysis-based detection. Using the latest summary of universal 16S sequence motifs present in literature and testing our design with 500 liquid and 50 formed stool samples, we illustrate the performance characteristics of a new 16S quantitative PCR (qPCR) assay, which addresses well-known technical problems, including a) positive priming reaction in the absence of intended target due to self-priming and/or mispriming of unintended targets; b) amplification bias due to nonoptimal primer/probe coverage; and c) too large amplicons for clinical qPCR. Stool swabs ranked into bins of different bacterial loads show significant correlation with threshold cycle values of our new assay. To the best of our knowledge, this is the first description of qPCR assay measuring individual differences of total bacterial load present in human stool.
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Affiliation(s)
- Ivan Brukner
- Medical Faculty, McGill University, Montreal, Quebec, Canada; SMBD-Jewish General Hospital, Montreal, Quebec, Canada.
| | - Yves Longtin
- Medical Faculty, McGill University, Montreal, Quebec, Canada; SMBD-Jewish General Hospital, Montreal, Quebec, Canada
| | - Matthew Oughton
- Medical Faculty, McGill University, Montreal, Quebec, Canada; SMBD-Jewish General Hospital, Montreal, Quebec, Canada
| | | | - Andre Dascal
- Medical Faculty, McGill University, Montreal, Quebec, Canada; SMBD-Jewish General Hospital, Montreal, Quebec, Canada
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Zhang Z, Liu W, Xu H, Aguilar ZP, Shah NP, Wei H. Propidium monoazide combined with real-time PCR for selective detection of viable Staphylococcus aureus in milk powder and meat products. J Dairy Sci 2015; 98:1625-33. [PMID: 25582587 DOI: 10.3168/jds.2014-8938] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 11/08/2014] [Indexed: 11/19/2022]
Abstract
Staphylococcus aureus is a spherical, gram-positive, pathogenic bacterium commonly associated with bovine mastitis and clinical infections. It is also recognized as a pathogen that causes outbreaks of food poisoning. The objective of this study was to develop and evaluate a rapid and reliable technique that combines propidium monoazide (PMA) staining with real-time quantitative (q)PCR to detect and quantify viable cells of Staph. aureus in milk powder and meat products. The inclusivity and exclusivity of the assay were evaluated using 58 strains belonging to 14 species. Serial dilutions of Staph. aureus cells were used to establish a standard curve and to confirm the effect of PMA treatment. Milk powder and meat products were used as the spiked foods, and the ability of PMA-qPCR to eliminate nonviable cells was determined in milk powder. Furthermore, meat products were inoculated with different concentrations of Staph. aureus and 10(5) cfu/g of Bacillus cereus and Salmonella enterica to test the interference by nontarget microorganisms. When PMA treatment was applied before DNA extraction, we were able to eliminate false-positive results with little effect on viable cells. The PMA-qPCR assay was specific and more sensitive than conventional PCR, and the level of detection was 3.0×10(2) cfu/g in spiked milk powder. Additionally, we observed no significant interference for the detection of viable Staph. aureus from other nontarget bacteria. The PMA-qPCR protocol is an effective and rapid method to quantify viable cells of Staph. aureus in food samples. The PMA-qPCR assay is specific and reliable, offering a valuable diagnostic tool for routine analysis in food and clinical diagnostic research at a reasonable cost.
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Affiliation(s)
- Zhihong Zhang
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Wenting Liu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Hengyi Xu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | | | - Nagendra P Shah
- Food and Nutritional Science, School of Biological Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
| | - Hua Wei
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
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Rapid detection of Staphylococcus aureus by loop-mediated isothermal amplification. Appl Biochem Biotechnol 2014; 175:882-91. [PMID: 25349088 DOI: 10.1007/s12010-014-1328-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/15/2014] [Indexed: 01/15/2023]
Abstract
Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), is a major bacterial pathogen associated with nosocomial and community-acquired S. aureus infections all over the world. A rapid detection assay for staphylococcal gene of nuc and mecA is needed. In this study, a rapid identification assay based on the loop-mediated isothermal amplification (LAMP) method was established. PCR and LAMP assays were used to detect Staphylococcus aureus and other related species for nuc and mecA. With optimization of the primers and reaction temperature, the LAMP successfully amplified the genes under isothermal conditions at 62 °C within 60 min, of which the results were identical with those of the conventional PCR methods. The detection limits of the LAMP for nuc and mecA were 1.47 and 14.7 pg/μl DNA per tube, respectively, by naked eye inspections, while the detection limits of the PCR for nuc and mecA were 14.7 pg/μl and 147 pg/μl DNA, respectively. Finally, The LAMP method was then applied to clinical blood plaque samples. The LAMP and PCR demonstrated identical results for the plaque samples with the culture assay. Together, the LAMP offers an alternative detection assay for nuc and mecA with a great advantage of the sensitivity and rapidity.
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Evaluation of the BD Max MRSA XT assay for use with different swab types. J Clin Microbiol 2014; 52:4343-6. [PMID: 25232162 DOI: 10.1128/jcm.02306-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We evaluated the performance of the BD Max MRSA XT assay for use with different swab types. The 90% detection rates (95% confidence intervals) were 387 (97 to 1,551), 877 (238 to 3,230), 986 (183 to 5,287), 1,292 (328 to 5,078), 2,400 (426 to 13,518), and 5,848 (622 to 55,021) CFU/swab for Liquid Stuart, Liquid Amies, dry, Amies Gel without charcoal, ESwab collection, and Amies gel with charcoal swabs (Becton Dickinson), respectively. Amies Gel without charcoal, ESwab collection, and Amies gel with charcoal swabs had a tendency to be less sensitive, but none of the differences was statistically significant.
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Parriott AM, Chow AL, Arah OA. Inadequate research on methicillin-resistant Staphylococcus aureus risk among postpartum women. Expert Rev Anti Infect Ther 2014; 11:1127-30. [PMID: 24151831 DOI: 10.1586/14787210.2013.850027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Andrea M Parriott
- Department of Health Policy and Management, Fielding School of Public Health, University of California, Los Angeles (UCLA), CA 90095-1772, USA
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A rapid and high-throughput screening approach for methicillin-resistant Staphylococcus aureus based on the combination of two different real-time PCR assays. J Clin Microbiol 2014; 52:2861-7. [PMID: 24871220 DOI: 10.1128/jcm.00808-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen that has been responsible for major nosocomial epidemics worldwide. For infection control programs, rapid and adequate detection of MRSA is of great importance. We developed a rapid and high-throughput molecular screening approach that consists of an overnight selective broth enrichment, followed by mecA, mecC, and S. aureus-specific (SA442 gene) real-time PCR assays, with subsequent confirmation using a staphylococcal cassette chromosome mec element (SCCmec)-orfX-based real-time PCR assay (GeneOhm MRSA assay) and culture. Here, the results of the screening approach over a 2-year period are presented. During this period, a total of 13,387 samples were analyzed for the presence of MRSA, 2.6% of which were reported as MRSA positive. No MRSA isolates carrying the mecC gene were detected during this study. Based on the results of the real-time PCR assays only, 95.2% of the samples could be reported as negative within 24 h. Furthermore, the performance of these real-time PCR assays was evaluated using a set of 104 assorted MRSA isolates, which demonstrated high sensitivity for both the combination of mecA and mecC with SA442 and the BD GeneOhm MRSA assay (98.1% and 97.1%, respectively). This molecular screening approach proved to be an accurate method for obtaining reliable negative results within 24 h after arrival at the laboratory and contributes to improvement of infection control programs, especially in areas with a low MRSA prevalence.
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