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Elbehiry A, Marzouk E, Moussa I, Anagreyyah S, AlGhamdi A, Alqarni A, Aljohani A, Hemeg HA, Almuzaini AM, Alzaben F, Abalkhail A, Alsubki RA, Najdi A, Algohani N, Abead B, Gazzaz B, Abu-Okail A. Using Protein Fingerprinting for Identifying and Discriminating Methicillin Resistant Staphylococcus aureus Isolates from Inpatient and Outpatient Clinics. Diagnostics (Basel) 2023; 13:2825. [PMID: 37685363 PMCID: PMC10486511 DOI: 10.3390/diagnostics13172825] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/25/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
In hospitals and other clinical settings, Methicillin-resistant Staphylococcus aureus (MRSA) is a particularly dangerous pathogen that can cause serious or even fatal infections. Thus, the detection and differentiation of MRSA has become an urgent matter in order to provide appropriate treatment and timely intervention in infection control. To ensure this, laboratories must have access to the most up-to-date testing methods and technology available. This study was conducted to determine whether protein fingerprinting technology could be used to identify and distinguish MRSA recovered from both inpatients and outpatients. A total of 326 S. aureus isolates were obtained from 2800 in- and outpatient samples collected from King Faisal Specialist Hospital and Research Centre in Riyadh, Saudi Arabia, from October 2018 to March 2021. For the phenotypic identification of 326 probable S. aureus cultures, microscopic analysis, Gram staining, a tube coagulase test, a Staph ID 32 API system, and a Vitek 2 Compact system were used. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), referred to as protein fingerprinting, was performed on each bacterial isolate to determine its proteomic composition. As part of the analysis, Principal Component Analysis (PCA) and a single-peak analysis of MALDI-TOF MS software were also used to distinguish between Methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA. According to the results, S. aureus isolates constituted 326 out of 2800 (11.64%) based on the culture technique. The Staph ID 32 API system and Vitek 2 Compact System were able to correctly identify 262 (80.7%) and 281 (86.2%) S. aureus strains, respectively. Based on the Oxacillin Disc Diffusion Method, 197 (62.23%) of 326 isolates of S. aureus exhibited a cefoxitin inhibition zone of less than 21 mm and an oxacillin inhibition zone of less than 10 mm, and were classified as MRSA under Clinical Laboratory Standards Institute guidelines. MALDI-TOF MS was able to correctly identify 100% of all S. aureus isolates with a score value equal to or greater than 2.00. In addition, a close relationship was found between S. aureus isolates and higher peak intensities in the mass ranges of 3990 Da, 4120 Da, and 5850 Da, which were found in MRSA isolates but absent in MSSA isolates. Therefore, protein fingerprinting has the potential to be used in clinical settings to rapidly detect and differentiate MRSA isolates, allowing for more targeted treatments and improved patient outcomes.
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Affiliation(s)
- Ayman Elbehiry
- Department of Public Health, College of Public Health and Health Informatics, Qassim University, Al Bukayriyah 52741, Saudi Arabia
- Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, University of Sadat City, Sadat City 32511, Egypt
| | - Eman Marzouk
- Department of Public Health, College of Public Health and Health Informatics, Qassim University, Al Bukayriyah 52741, Saudi Arabia
| | - Ihab Moussa
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Sulaiman Anagreyyah
- Family Medicine Department, King Fahad Armed Forces Hospital, Jeddah 23311, Saudi Arabia
| | - Abdulaziz AlGhamdi
- Medical Director Office, North Area Armed Forces Hospital, King Khalid Military City 39747, Saudi Arabia
| | - Ali Alqarni
- Respiratory Therapy Department, Armed Forces Hospital Dhahran, Dhahran 34641, Saudi Arabia
| | - Ahmed Aljohani
- Patient Affairs Department, Sharourah Armed Forces Hospital, Sharourah 68372, Saudi Arabia
| | - Hassan A. Hemeg
- Department of Medical Technology/Microbiology, College of Applied Medical Science, Taibah University, Madina 30001, Saudi Arabia
| | - Abdulaziz M. Almuzaini
- Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, Buraydah 52571, Saudi Arabia
| | - Feras Alzaben
- Department of Food Service, King Fahad Armed Forces Hospital, Jeddah 23311, Saudi Arabia
| | - Adil Abalkhail
- Department of Public Health, College of Public Health and Health Informatics, Qassim University, Al Bukayriyah 52741, Saudi Arabia
| | - Roua A. Alsubki
- Department of Clinical Laboratory Science, College of Applied Medical Science, King Saud University, Riyadh 11433, Saudi Arabia
| | - Ali Najdi
- Northern Area Armed Forces Hospital, King Khalid Military City 39748, Saudi Arabia
| | - Nawaf Algohani
- Consultant Forensic Medicine, Forensic Medicine Center, Madina 42319, Saudi Arabia
| | - Banan Abead
- Support Service Department, King Fahad Armed Forces Hospital, Jeddah 23311, Saudi Arabia;
| | - Bassam Gazzaz
- Patient Affairs Department, King Fahad Armed Forces Hospital, Jeddah 23311, Saudi Arabia
| | - Akram Abu-Okail
- Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, Buraydah 52571, Saudi Arabia
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Sohrabi H, Majidi MR, Khaki P, Jahanban-Esfahlan A, de la Guardia M, Mokhtarzadeh A. State of the art: Lateral flow assays toward the point-of-care foodborne pathogenic bacteria detection in food samples. Compr Rev Food Sci Food Saf 2022; 21:1868-1912. [PMID: 35194932 DOI: 10.1111/1541-4337.12913] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/18/2021] [Accepted: 12/23/2021] [Indexed: 12/24/2022]
Abstract
Diverse chemicals and some physical phenomena recently introduced in nanotechnology have enabled scientists to develop useful devices in the field of food sciences. Concerning such developments, detecting foodborne pathogenic bacteria is now an important issue. These kinds of bacteria species have demonstrated severe health effects after consuming foods and high mortality related to acute cases. The most leading path of intoxication and infection has been through food matrices. Hence, quick recognition of foodborne bacteria agents at low concentrations has been required in current diagnostics. Lateral flow assays (LFAs) are one of the urgent and prevalently applied quick recognition methods that have been settled for recognizing diverse types of analytes. Thus, the present review has stressed on latest developments in LFAs-based platforms to detect various foodborne pathogenic bacteria such as Salmonella, Listeria, Escherichia coli, Brucella, Shigella, Staphylococcus aureus, Clostridium botulinum, and Vibrio cholera. Proper prominence has been given on exactly how the labels, detection elements, or procedures have affected recent developments in the evaluation of diverse bacteria using LFAs. Additionally, the modifications in assays specificity and sensitivity consistent with applied food processing techniques have been discussed. Finally, a conclusion has been drawn for highlighting the main challenges confronted through this method and offered a view and insight of thoughts for its further development in the future.
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Affiliation(s)
- Hessamaddin Sohrabi
- Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran
| | - Mir Reza Majidi
- Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran
| | - Pegah Khaki
- Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran
| | - Ali Jahanban-Esfahlan
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Biology, Faculty of Fundamental Sciences, University College of Nabi Akram (UCNA), Tabriz, Iran
| | | | - Ahad Mokhtarzadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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Dekter HE, Orelio CC, Morsink MC, Tektas S, Vis B, Te Witt R, van Leeuwen WB. Antimicrobial susceptibility testing of Gram-positive and -negative bacterial isolates directly from spiked blood culture media with Raman spectroscopy. Eur J Clin Microbiol Infect Dis 2016; 36:81-89. [PMID: 27638006 DOI: 10.1007/s10096-016-2773-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/30/2016] [Indexed: 11/24/2022]
Abstract
Patients suffering from bacterial bloodstream infections have an increased risk of developing systematic inflammatory response syndrome (SIRS), which can result in rapid deterioration of the patients' health. Diagnostic methods for bacterial identification and antimicrobial susceptibility tests are time-consuming. The aim of this study was to investigate whether Raman spectroscopy would be able to rapidly provide an antimicrobial susceptibility profile from bacteria isolated directly from positive blood cultures. First, bacterial strains (n = 133) were inoculated in tryptic soy broth and incubated in the presence or absence of antibiotics for 5 h. Antimicrobial susceptibility profiles were analyzed by Raman spectroscopy. Subsequently, a selection of strains was isolated from blood cultures and analyzed similarly. VITEK®2 technology and broth dilution were used as the reference methods. Raman spectra from 67 antibiotic-susceptible strains showed discriminatory spectra in the absence or at low concentrations of antibiotics as compared to high antibiotic concentrations. For 66 antibiotic-resistant strains, no antimicrobial effect was observed on the bacterial Raman spectra. Full concordance with VITEK®2 data and broth dilution was obtained for the antibiotic-susceptible strains, 68 % and 98 %, respectively, for the resistant strains. Discriminative antimicrobial susceptibility testing (AST) profiles were obtained for all bacterial strains isolated from blood cultures, resulting in full concordance with the VITEK®2 data. It can be concluded that Raman spectroscopy is able to detect the antimicrobial susceptibility of bacterial species isolated from a positive blood culture bottle within 5 h. Although Raman spectroscopy is cheap and rapid, further optimization is required, to fulfill a great promise for future AST profiling technology development.
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Affiliation(s)
- H E Dekter
- Research Department of Innovative Molecular Diagnostics, University of Applied Sciences Leiden, J. H. Oortweg 21, 2333 CH, Leiden, The Netherlands
| | - C C Orelio
- Research Department of Innovative Molecular Diagnostics, University of Applied Sciences Leiden, J. H. Oortweg 21, 2333 CH, Leiden, The Netherlands
| | - M C Morsink
- Research Department of Innovative Molecular Diagnostics, University of Applied Sciences Leiden, J. H. Oortweg 21, 2333 CH, Leiden, The Netherlands
| | - S Tektas
- Research Department of Innovative Molecular Diagnostics, University of Applied Sciences Leiden, J. H. Oortweg 21, 2333 CH, Leiden, The Netherlands
| | - B Vis
- Research Department of Innovative Molecular Diagnostics, University of Applied Sciences Leiden, J. H. Oortweg 21, 2333 CH, Leiden, The Netherlands
| | - R Te Witt
- Netherlands Molecular Diagnostic Laboratory B.V. (NMDL), Visseringlaan 25, 2288 ER, Rijswijk, The Netherlands
| | - W B van Leeuwen
- Research Department of Innovative Molecular Diagnostics, University of Applied Sciences Leiden, J. H. Oortweg 21, 2333 CH, Leiden, The Netherlands.
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Bacterial nanoscale cultures for phenotypic multiplexed antibiotic susceptibility testing. J Clin Microbiol 2014; 52:3310-7. [PMID: 24989602 DOI: 10.1128/jcm.01161-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
An optimal antimicrobial drug regimen is the key to successful clinical outcomes of bacterial infections. To direct the choice of antibiotic, access to fast and precise antibiotic susceptibility profiling of the infecting bacteria is critical. We have developed a high-throughput nanowell antibiotic susceptibility testing (AST) device for direct, multiplexed analysis. By processing in real time the optical recordings of nanoscale cultures of reference and clinical uropathogenic Escherichia coli strains with a mathematical algorithm, the time point when growth shifts from lag phase to early logarithmic phase (Tlag) was identified for each of the several hundreds of cultures tested. Based on Tlag, the MIC could be defined within 4 h. Heatmap presentation of data from this high-throughput analysis allowed multiple resistance patterns to be differentiated at a glance. With a possibility to enhance multiplexing capacity, this device serves as a high-throughput diagnostic tool that rapidly aids clinicians in prescribing the optimal antibiotic therapy.
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Comparative evaluation of Vitek 2 identification and susceptibility testing of urinary tract pathogens directly and isolated from chromogenic media. Eur J Clin Microbiol Infect Dis 2013; 32:773-80. [DOI: 10.1007/s10096-012-1806-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/14/2012] [Indexed: 10/27/2022]
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Romero-Gómez MP, Gómez-Gil R, Paño-Pardo JR, Mingorance J. Identification and susceptibility testing of microorganism by direct inoculation from positive blood culture bottles by combining MALDI-TOF and Vitek-2 Compact is rapid and effective. J Infect 2012; 65:513-20. [DOI: 10.1016/j.jinf.2012.08.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 10/27/2022]
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Giani T, Morosini M, D'Andrea M, García-Castillo M, Rossolini G, Cantón R. Assessment of the Phoenix™ automated system and EUCAST breakpoints for antimicrobial susceptibility testing against isolates expressing clinically relevant resistance mechanisms. Clin Microbiol Infect 2012; 18:E452-8. [DOI: 10.1111/j.1469-0691.2012.03980.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Boot R. Frequent major errors in antimicrobial susceptibility testing of bacterial strains distributed under the Deutsches Krebsforschungszentrum Quality Assurance Program. Lab Anim 2012; 46:253-7. [PMID: 22723648 DOI: 10.1258/la.2012.011085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Quality Assurance Program (QAP) of the Deutsches Krebsforschungszentrum (DKFZ) was a proficiency testing system developed to service the laboratory animal discipline. The QAP comprised the distribution of bacterial strains from various species of animals for identification to species level and antibiotic susceptibility testing (AST). Identification capabilities were below acceptable standards. This study evaluated AST results using the DKFZ compilations of test results for all bacterial strains showing the number of participants reporting the strain as resistant (R), sensitive (S) or intermediate susceptible (I) to each antibiotic substance used. Due to lack of information about methods used, it was assumed that what the majority of the participants reported (R or S) was the correct test result and that an opposite result was a major error (ME). MEs occurred in 1375 of 14,258 (9.7%) of test results and ME% ranged from 0% to 23.2% per bacterial group-agent group combination. Considerable variation in MEs was found within groups of bacteria and within groups of agents. In addition to poor performance in proper species classification, the quality of AST in laboratory animal diagnostic laboratories seems far below standards considered acceptable in human diagnostic microbiology.
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Affiliation(s)
- R Boot
- Former Section of Laboratory Animal Microbiology, Diagnostic Laboratory for Infectious Diseases, National Institute of Public Health and the Environment, PO Box 1, 3720 BA Bilthoven, The Netherlands.
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Abstract
This review aims to discuss expert systems in general and how they may be used in medicine as a whole and clinical microbiology in particular (with the aid of interpretive reading). It considers rule-based systems, pattern-based systems, and data mining and introduces neural nets. A variety of noncommercial systems is described, and the central role played by the EUCAST is stressed. The need for expert rules in the environment of reset EUCAST breakpoints is also questioned. Commercial automated systems with on-board expert systems are considered, with emphasis being placed on the "big three": Vitek 2, BD Phoenix, and MicroScan. By necessity and in places, the review becomes a general review of automated system performances for the detection of specific resistance mechanisms rather than focusing solely on expert systems. Published performance evaluations of each system are drawn together and commented on critically.
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Affiliation(s)
- Trevor Winstanley
- Department of Microbiology, Royal Hallamshire Hospital, Sheffield, United Kingdom.
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Endimiani A, Hujer KM, Hujer AM, Kurz S, Jacobs MR, Perlin DS, Bonomo RA. Are we ready for novel detection methods to treat respiratory pathogens in hospital-acquired pneumonia? Clin Infect Dis 2011; 52 Suppl 4:S373-83. [PMID: 21460299 PMCID: PMC3106236 DOI: 10.1093/cid/cir054] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hospital-acquired pneumonia represents one of the most difficult treatment challenges in infectious diseases. Many studies suggest that the timely administration of appropriate, pathogen-directed therapy can be lifesaving. Because results of culture and antimicrobial susceptibility testing can take 48 h or longer, physicians currently rely on clinical, epidemiological, and demographic factors to assist with the choice of empiric therapy for antibiotic-resistant pathogens. At present, a number of rapid molecular tests are being developed that identify pathogens and the presence of genetic determinants of antimicrobial resistance (eg, GeneXpert [Cepheid], ResPlex [Qiagen], FilmArray [Idaho Technologies], and Microarray [Check-Points]). In this review, the potential impact that molecular diagnostics has to identify and characterize pathogens that cause hospital-acquired bacterial pneumonia at an early stage is examined. In addition, a perspective on a novel technology, polymerase chain reaction followed by electrospray ionization mass spectrometry, is presented, and its prospective use in the diagnosis of pneumonia is also discussed. The complexities of the pulmonary microbiome represent a novel challenge to clinicians, but many questions still remain even as these technologies improve.
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Affiliation(s)
- Andrea Endimiani
- Department of Medicine
- Department of Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
| | - Kristine M. Hujer
- Department of Medicine
- Department of Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
| | - Andrea M. Hujer
- Department of Medicine
- Department of Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
| | - Sebastian Kurz
- Department of Medicine
- Department of Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
| | | | - David S. Perlin
- Public Health Research Institute
- Department of Microbiology and Molecular Genetics, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey
| | - Robert A. Bonomo
- Department of Medicine
- Department of Pharmacology
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine
- Department of Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
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Torres E, Villanueva R, Bou G. Comparison of different methods of determining β-lactam susceptibility in clinical strains of Pseudomonas aeruginosa. J Med Microbiol 2009; 58:625-629. [DOI: 10.1099/jmm.0.005587-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One hundred and one randomly selected (2003–2005) clinical isolates ofPseudomonas aeruginosawere used to assess the quantitative (MIC) and qualitative (susceptibility category) agreement between the microdilution broth reference method (RM) and disc diffusion (DD), Etest and the VITEK 2 automated susceptibility test system for determination of the susceptibility ofP. aeruginosato piperacillin (PIP), PIP–tazobactam (TZP), ceftazidime (CAZ), aztreonam (ATM) cefepime (FEP) and imipenem (IMP). The results obtained by the RM were compared with those obtained by the other methods. The RM and DD were performed according to CLSI criteria. Etest and VITEK 2 were according to the manufacturer's instructions. The Advanced Expert System (AES), which interprets MICs generated by VITEK 2, was modified with new rules of interpretation. Overall, VITEK 2 showed the lowest MIC90values for the six antibiotics. The RM categorical testing (susceptibility and resistance) rates withP. aeruginosawere 11.8 and 88.1 for PIP, 22.7 and 77.2 for TZP, 14.8 and 78.2 for CAZ, 12.8 and 54.4 for ATM, 16.8 and 75.3 for FEP, and 7.9 and 90.1 for IMP, respectively. Very major errors (false susceptible) were only detected for ATM and FEP with DD and for IMP with three methods. Major errors (false resistant) were generally acceptable for all antibiotics except TZP. VITEK 2 yielded a high level of minor errors (trends toward false susceptibility), mainly with CAZ and FEP. A good agreement was obtained for all antibiotics/methods assayed, thus highlighting the importance of the AES for categorization ofβ-lactam susceptibility inP. aeruginosa.
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Affiliation(s)
- Eva Torres
- Servicio de Microbiología – Unidad de Investigación, Complejo Hospitalario Universitario Juan Canalejo, La Coruña, Spain
| | - Rosa Villanueva
- Servicio de Microbiología – Unidad de Investigación, Complejo Hospitalario Universitario Juan Canalejo, La Coruña, Spain
| | - Germán Bou
- Servicio de Microbiología – Unidad de Investigación, Complejo Hospitalario Universitario Juan Canalejo, La Coruña, Spain
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Detecting imipenem resistance in Acinetobacter baumannii by automated systems (BD Phoenix, Microscan WalkAway, Vitek 2); high error rates with Microscan WalkAway. BMC Infect Dis 2009; 9:30. [PMID: 19291298 PMCID: PMC2664816 DOI: 10.1186/1471-2334-9-30] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 03/16/2009] [Indexed: 11/10/2022] Open
Abstract
Background Increasing reports of carbapenem resistant Acinetobacter baumannii infections are of serious concern. Reliable susceptibility testing results remains a critical issue for the clinical outcome. Automated systems are increasingly used for species identification and susceptibility testing. This study was organized to evaluate the accuracies of three widely used automated susceptibility testing methods for testing the imipenem susceptibilities of A. baumannii isolates, by comparing to the validated test methods. Methods Selected 112 clinical isolates of A. baumanii collected between January 2003 and May 2006 were tested to confirm imipenem susceptibility results. Strains were tested against imipenem by the reference broth microdilution (BMD), disk diffusion (DD), Etest, BD Phoenix, MicroScan WalkAway and Vitek 2 automated systems. Data were analysed by comparing the results from each test method to those produced by the reference BMD test. Results MicroScan performed true identification of all A. baumannii strains while Vitek 2 unidentified one strain, Phoenix unidentified two strains and misidentified two strains. Eighty seven of the strains (78%) were resistant to imipenem by BMD. Etest, Vitek 2 and BD Phoenix produced acceptable error rates when tested against imipenem. Etest showed the best performance with only two minor errors (1.8%). Vitek 2 produced eight minor errors(7.2%). BD Phoenix produced three major errors (2.8%). DD produced two very major errors (1.8%) (slightly higher (0.3%) than the acceptable limit) and three major errors (2.7%). MicroScan showed the worst performance in susceptibility testing with unacceptable error rates; 28 very major (25%) and 50 minor errors (44.6%). Conclusion Reporting errors for A. baumannii against imipenem do exist in susceptibility testing systems. We suggest clinical laboratories using MicroScan system for routine use should consider using a second, independent antimicrobial susceptibility testing method to validate imipenem susceptibility. Etest, whereever available, may be used as an easy method to confirm imipenem susceptibility.
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Ertapenem resistance among extended-spectrum-beta-lactamase-producing Klebsiella pneumoniae isolates. J Clin Microbiol 2009; 47:969-74. [PMID: 19213695 DOI: 10.1128/jcm.00651-08] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ertapenem resistance in Klebsiella pneumoniae is rare. We report on an ertapenem-nonsusceptible phenotype among 25 out of 663 (3.77%) extended-spectrum-beta-lactamase (ESBL)-producing K. pneumoniae isolates in a multicenter Israeli study. These isolates originated from six different hospitals and were multiclonal, belonging to 12 different genetic clones. Repeat testing using Etest and agar dilution confirmed ertapenem nonsusceptibility in only 15/663 (2.3%) of the isolates. The molecular mechanisms of ertapenem resistance in seven single-clone resistant isolates was due to the presence of ESBL genes (CTX-M-2 in four isolates, CTX-M-10 and OXA-4 in one isolate, SHV-12 in one isolate, and SHV-28 in one isolate) combined with the absence of OMPK36. Seven of 10 isolates initially reported as ertapenem nonsusceptible and subsequently classified as susceptible showed an inoculum effect with ertapenem but not with imipenem or meropenem. Population analysis detected the presence of an ertapenem-resistant subpopulation at a frequency of 10(-6). These rare resistant subpopulations carried multiple ESBL genes, including TEM-30, SHV-44, CTX-M-2, and CTX-M-10, and they lacked OMPK36. The clinical and diagnostic significance of the results should be further studied.
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Habib Babay HA, Manneh K, Somily AM. Accuracy of Detecting Resistance to Carbapenems among Gram Negative Rods: Comparison of Three Methods. J Taibah Univ Med Sci 2009. [DOI: 10.1016/s1658-3612(09)70081-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Nayak R, Call V, Kaldhone P, Tyler C, Anderson G, Phillips S, Kerdahi K, Foley SL. Comparison of Salmonella enterica serovar Heidelberg susceptibility testing results. Clin Med Res 2007; 5:98-105. [PMID: 17607044 PMCID: PMC1905935 DOI: 10.3121/cmr.2007.725] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Disk diffusion and broth dilution assays are conventionally used for antimicrobial susceptibility testing (AST) of bacteria. The goal of this study was to determine the correlation of results from different AST methods for the Salmonella enterica serovar Heidelberg. DESIGN S. enterica serovar Heidelberg (n=105) strains were tested using 4 different AST methods: agar disk diffusion, broth microdilution using Sensititre with the NARMS (CMV1AGNF) panel, manual broth microdilution and Vitek with GNS-207 cards. METHODS AST was performed using standardized methods and Clinical and Laboratory Standards Institute recommended quality control organisms. Eight drugs were common to all testing methods including amikacin, amoxicillin/clavulanic acid, ampicillin, chloramphenicol, ciprofloxacin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole. RESULTS No resistance to amikacin and ciprofloxacin was detected. Overall, the agreement of the AST results among all four methods for the drugs tested was: amikacin (100%), amoxicillin/clavulanic acid (96.1%), ampicillin (97.1%), chloramphenicol (96.2%), ciprofloxacin (100%), gentamicin (80.0%), tetracycline (80.0%) and trimethoprim/sulfamethoxazole (94.3%). There was 97.1%, 95.5% and 98.0% overall agreement between the reference diffusion method and the manual broth microdilution, Sensititre microdilution and Vitek methods, respectively. CONCLUSION The study indicated that AST methods correlated with one another when testing S. enterica serovar Heidelberg isolates, with a few exceptions. In general, discrepancies among the methods were due to isolates being interpreted as intermediately susceptible or due to an increased number of resistances detected with Sensititre and a lower number with Vitek.
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Affiliation(s)
- Rajesh Nayak
- National Center for Toxicological Research, United States Food and Drug Administration, Jefferson, Arkansas, USA
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Mesaros N, Nordmann P, Plésiat P, Roussel-Delvallez M, Van Eldere J, Glupczynski Y, Van Laethem Y, Jacobs F, Lebecque P, Malfroot A, Tulkens PM, Van Bambeke F. Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium. Clin Microbiol Infect 2007; 13:560-78. [PMID: 17266725 DOI: 10.1111/j.1469-0691.2007.01681.x] [Citation(s) in RCA: 384] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.
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Affiliation(s)
- N Mesaros
- Unité de Pharmacologie cellulaire and moléculaire, Université catholique de Louvain, Bruxelles, Belgium
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17
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Tenover FC, Kalsi RK, Williams PP, Carey RB, Stocker S, Lonsway D, Rasheed JK, Biddle JW, McGowan JE, Hanna B. Carbapenem resistance in Klebsiella pneumoniae not detected by automated susceptibility testing. Emerg Infect Dis 2006; 12:1209-13. [PMID: 16965699 PMCID: PMC3291231 DOI: 10.3201/eid1208.060291] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Detecting β-lactamase–mediated carbapenem resistance among Klebsiella pneumoniae isolates and other Enterobacteriaceae is an emerging problem. In this study, 15 blaKPC-positive Klebsiella pneumoniae that showed discrepant results for imipenem and meropenem from 4 New York City hospitals were characterized by isoelectric focusing; broth microdilution (BMD); disk diffusion (DD); and MicroScan, Phoenix, Sensititre, VITEK, and VITEK 2 automated systems. All 15 isolates were either intermediate or resistant to imipenem and meropenem by BMD; 1 was susceptible to imipenem by DD. MicroScan and Phoenix reported 1 (6.7%) and 2 (13.3%) isolates, respectively, as imipenem susceptible. VITEK and VITEK 2 reported 10 (67%) and 5 (33%) isolates, respectively, as imipenem susceptible. By Sensititre, 13 (87%) isolates were susceptible to imipenem, and 12 (80%) were susceptible to meropenem. The VITEK 2 Advanced Expert System changed 2 imipenem MIC results from >16 μg/mL to <2 μg/mL but kept the interpretation as resistant. The recognition of carbapenem-resistant K. pneumoniae continues to challenge automated susceptibility systems.
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Affiliation(s)
- Fred C Tenover
- Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, USA.
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18
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Menozzi MG, Eigner U, Covan S, Rossi S, Somenzi P, Dettori G, Chezzi C, Fahr AM. Two-center collaborative evaluation of performance of the BD phoenix automated microbiology system for identification and antimicrobial susceptibility testing of gram-negative bacteria. J Clin Microbiol 2006; 44:4085-94. [PMID: 17005752 PMCID: PMC1698323 DOI: 10.1128/jcm.00614-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems, Sparks, MD) was assessed for identification (ID) and antimicrobial susceptibility testing (AST) of the majority of clinically encountered bacterial isolates in a European collaborative two-center trial. A total of 494 bacterial isolates including various species of the Enterobacteriaceae and 110 nonfermentative gram-negative bacteria were investigated: of these, 385 were single patient isolates, and 109 were challenge strains tested at one center. The performance of the Phoenix extended-spectrum beta-lactamase (ESBL) test was also evaluated for 203 strains of Escherichia coli, Klebsiella pneumoniae, and Klebsiella oxytoca included in the study. Forty-two antimicrobial drugs were tested, including members of the following drug classes: aminoglycosides, beta-lactam antibiotics, beta-lactam/beta-lactamase inhibitors, carbapenems, cephems, monobactams, folate antagonists, quinolones, and others. Phoenix system ID results were compared to those of the laboratories' routine ID systems (API 20E and API CHE, ATB ID32E, ID32GN, and VITEK 2 [bioMérieux, Marcy l'Etoile, France]); Phoenix AST results were compared to those of frozen standard broth microdilution (SBM) panels according to NCCLS (now CLSI) guidelines (NCCLS document M100-S9, approved standard M7-A4). Discrepant results were repeated in duplicate. Concordant IDs of 98.4 and 99.1% were observed for the Enterobacteriaceae and the nonfermentative group, respectively. For AST results, the overall essential agreement was 94.2%; the category agreement was 97.3%; and the very major error rate, major error rate, and minor error rate were 1.6, 0.6, and 1.9%, respectively. In terms of ESBL detection, Phoenix results were 98.5% concordant with those of the reference system, with 98.0% sensitivity and 98.7% specificity. In conclusion, the Phoenix ID results showed high agreement with results of the systems to which they were being compared: the AST performance was highly equivalent to that of the SBM reference method, and the system proved to be very accurate for the detection of ESBL producers.
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Affiliation(s)
- Maria Grazia Menozzi
- Section of Microbiology, Department of Pathology and Laboratory Medicine, University of Parma, Viale Antonio Gramsci, 14, 43100 Parma, Italy.
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19
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Sader HS, Fritsche TR, Jones RN. Accuracy of three automated systems (MicroScan WalkAway, VITEK, and VITEK 2) for susceptibility testing of Pseudomonas aeruginosa against five broad-spectrum beta-lactam agents. J Clin Microbiol 2006; 44:1101-4. [PMID: 16517904 PMCID: PMC1393142 DOI: 10.1128/jcm.44.3.1101-1104.2006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One hundred recent clinical Pseudomonas aeruginosa isolates were used to assess the quantitative (MIC) and qualitative (susceptibility category) accuracies of the MicroScan WalkAway, VITEK, and VITEK 2 automated susceptibility test systems when five-broad spectrum beta-lactams, aztreonam, cefepime, ceftazidime, imipenem, and piperacillin-tazobactam, were tested. Isolates were selected so that the MICs for the isolates overrepresented the MICs near the breakpoints to assess precisely the agreement between the results obtained with the automated systems and the results obtained by the reference tests. The categorical and MIC results from the automated systems were compared to the consensus result of three reference methods: broth microdilution, agar dilution, and disk diffusion. The consensus categorical testing (susceptibility and resistance) rates were 47 and 27%, respectively, for aztreonam; 59 and 14%, respectively, for cefepime; 44 and 43%, respectively, for ceftazidime; 71 and 19%, respectively, for imipenem; and 50 and 50%, respectively, for piperacillin-tazobactam. All systems tested exhibited a high, unacceptable level of very major (false-susceptible) errors for piperacillin-tazobactam (19 to 27%). Major (false-resistant) error rates were generally acceptable (0 to 3%), but minor error rates were elevated (8 to 32%) for cefepime (VITEK 2 and VITEK) and for aztreonam (all three systems), leading to consistent trends toward false resistance. Manufacturer reevaluation of these automated systems for the testing of selected beta-lactams with current clinical isolates of P. aeruginosa that exhibit contemporary resistance mechanisms would be prudent to minimize the potential for serious reporting errors.
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Affiliation(s)
- Helio S Sader
- JMI Laboratories, Inc., 345 Beaver Kreek Centre, Suite A, North Liberty, Iowa 52317, USA.
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20
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Giakkoupi P, Tzouvelekis LS, Daikos GL, Miriagou V, Petrikkos G, Legakis NJ, Vatopoulos AC. Discrepancies and interpretation problems in susceptibility testing of VIM-1-producing Klebsiella pneumoniae isolates. J Clin Microbiol 2005; 43:494-6. [PMID: 15635025 PMCID: PMC540174 DOI: 10.1128/jcm.43.1.494-496.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Susceptibilities to beta-lactam antibiotics of five VIM-1-producing Klebsiella pneumoniae isolates were determined by broth microdilution, Etest, disk diffusion, and the automated systems Vitek 2, Phoenix, and MicroScan. Significant discrepancies were observed in the determination of susceptibility to imipenem and meropenem. Interpretation problems by the automated systems were also noted.
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Affiliation(s)
- P Giakkoupi
- Department of Microbiology, National School of Public Health, 196 Alexandras Ave., Athens 11521, Greece
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21
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Saegeman V, Huynen P, Colaert J, Melin P, Verhaegen J. Susceptibility testing of Pseudomonas aeruginosa by the Vitek 2 system: a comparison with Etest results. Acta Clin Belg 2005; 60:3-9. [PMID: 15981697 DOI: 10.1179/acb.2005.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
P. aeruginona infections need accurate antimicrobial susceptibility data, as treatment mainly relies on antibiotic efficiency in debilitated patients. Vitek 2, a popular automated susceptibility testing method, was compared with Etest to assess its reliability on 150 Belgian P. aeruginonas isolates. Vitek 2 and Etest exhibited a high degree of concordance, but some discrepancies in clinical category were evident for cefepime (high minor and borderline very major error rate) and for piperacillin/tazobactam (high very major error rate). Vitek 2 appears to yield valuable information to the clinician concerning the antimicrobials amikacin, ceftazidime, ciprofloxacin and meropenem, in the setting of pseudomonas infection. For cefepime and piperacillin/tazobactam, a confirmatory testing by means of disk diffusion is worth considering.
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Affiliation(s)
- V Saegeman
- UZ Gasthuisberg, KULeuven, Dept. Microbiologie, Herestraat 49, 3000 Leuven.
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22
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Chapin KC, Musgnug MC. Validation of the automated reading and incubation system with Sensititre plates for antimicrobial susceptibility testing. J Clin Microbiol 2003; 41:1951-6. [PMID: 12734233 PMCID: PMC154729 DOI: 10.1128/jcm.41.5.1951-1956.2003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present study compared the antimicrobial susceptibility testing (AST) results generated by the Automated Incubation and Reading System (ARIS) with custom Sensititre plates (TREK Diagnostic Systems, Cleveland, Ohio) and MicroScan PC10 GP and NUMIC10 GN plates interpreted with the WalkAway-96 system (Dade Behring, West Sacramento, Calif.) for gram-positive (GP) and gram-negative (GN) organisms as part of an in-house validation. A total of 326 isolates (3,689 antimicrobial agent-organism combinations) were evaluated. Sensititre plates were inoculated according to the instructions of the manufacturer with a suspension adjusted to a 0.5 McFarland standard, while the Prompt Inoculation System was used for the MicroScan plates. ARIS and the WalkAway system were used for automated reading of the Sensititre and MicroScan plates, respectively, at 18 to 24 h. The results were analyzed for essential (+/-1 twofold dilution) and categorical (sensitive, intermediate, or resistant) agreements. Plates that resulted in ARIS interpretations with major (falsely resistant) or very major (falsely susceptible) errors compared to the results obtained with the WalkAway system were read manually to corroborate instrument readings. Isolates for which very major or major errors were obtained and for which the results were not resolved by manual reading were retested in parallel. Isolates for which very major or major errors were obtained and for which the results were not resolved upon repeat testing were tested by the National Committee for Clinical Laboratory Standards M7-A5 frozen reference microdilution method. Essential agreement was 95.8% for 246 GN isolates. The following categorical error rates were obtained for the GN isolates: 1.3% minor errors, 0% major errors, and 0.4% very major errors. For 95 GP isolates, there was 93.5% essential agreement. Categorical error rates for GP isolates were 0.9% minor errors, 0.6% major errors, and 0.4% very major errors. ARIS-Sensititre is a diagnostic system feasible for use for automated AST in a clinical laboratory.
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Affiliation(s)
- Kimberle C Chapin
- Department of Laboratory Medicine, Lahey Clinic Medical Center, Burlington, Massachusetts 01805, USA.
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23
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Steward CD, Mohammed JM, Swenson JM, Stocker SA, Williams PP, Gaynes RP, McGowan JE, Tenover FC. Antimicrobial susceptibility testing of carbapenems: multicenter validity testing and accuracy levels of five antimicrobial test methods for detecting resistance in Enterobacteriaceae and Pseudomonas aeruginosa isolates. J Clin Microbiol 2003; 41:351-8. [PMID: 12517872 PMCID: PMC149638 DOI: 10.1128/jcm.41.1.351-358.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
From January 1996 to May 1999, Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology) received 448 nonduplicate clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa that were reported to be imipenem intermediate or resistant. However, broth microdilution (BMD) confirmatory testing at the Project ICARE central laboratory confirmed this result in only 11 of 123 (8.9%) Enterobacteriaceae isolates and 241 of 325 (74.2%) P. aeruginosa isolates. To investigate this overdetection of imipenem resistance, we tested 204 selected isolates from the Project ICARE collection plus five imipenem-resistant challenge strains at the Centers for Disease Control and Prevention against imipenem and meropenem by agar dilution, disk diffusion, Etest (AB BIODISK North America, Inc., Piscataway, N.J.), two MicroScan WalkAway conventional panels (Neg MIC Plus 3 and Neg Urine Combo 3) (Dade MicroScan, Inc., West Sacramento, Calif.), and two Vitek cards (GNS-116 containing meropenem and GNS-F7 containing imipenem) (bioMérieux Vitek, Inc., Durham, N.C.). The results of each test method were compared to the results of BMD testing using in-house-prepared panels. Seven imipenem-resistant and five meropenem-resistant isolates of Enterobacteriaceae and 43 imipenem-resistant and 21 meropenem-resistant isolates of P. aeruginosa were identified by BMD. For Enterobacteriaceae, the imipenem and meropenem test methods produced low numbers of very major and major errors. All test systems in the study produced low numbers of very major and major errors when P. aeruginosa was tested against imipenem and meropenem, except for Vitek testing (major error rate for imipenem, 20%). Further testing conducted in 11 of the participating ICARE hospital laboratories failed to pinpoint the factors responsible for the initial overdetection of imipenem resistance. However, this study demonstrated that carbapenem testing difficulties do exist and that laboratories should consider using a second, independent antimicrobial susceptibility testing method to validate carbapenem-intermediate and -resistant results.
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Affiliation(s)
- Christine D Steward
- Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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24
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Joyanes P, del Carmen Conejo M, Martínez-Martínez L, Perea EJ. Evaluation of the VITEK 2 system for the identification and susceptibility testing of three species of nonfermenting gram-negative rods frequently isolated from clinical samples. J Clin Microbiol 2001; 39:3247-53. [PMID: 11526158 PMCID: PMC88326 DOI: 10.1128/jcm.39.9.3247-3253.2001] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
VITEK 2 is a new automatic system for the identification and susceptibility testing of the most clinically important bacteria. In the present study 198 clinical isolates, including Pseudomonas aeruginosa (n = 146), Acinetobacter baumannii (n = 25), and Stenotrophomonas maltophilia (n = 27) were evaluated. Reference susceptibility testing of cefepime, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, imipenem, meropenem, piperacillin, tobramycin, levofloxacin (only for P. aeruginosa), co-trimoxazole (only for S. maltophilia), and ampicillin-sulbactam and tetracycline (only for A. baumannii) was performed by microdilution (NCCLS guidelines). The VITEK 2 system correctly identified 91.6, 100, and 76% of P. aeruginosa, S. maltophilia, and A. baumannii isolates, respectively, within 3 h. The respective percentages of essential agreement (to within 1 twofold dilution) for P. aeruginosa and A. baumannii were 89.0 and 88.0% (cefepime), 91.1 and 100% (cefotaxime), 95.2 and 96.0% (ceftazidime), 98.6 and 100% (ciprofloxacin), 88.4 and 100% (gentamicin), 87.0 and 92.0% (imipenem), 85.0 and 88.0% (meropenem), 84.2 and 96.0% (piperacillin), and 97.3 and 80% (tobramycin). The essential agreement for levofloxacin against P. aeruginosa was 86.3%. The percentages of essential agreement for ampicillin-sulbactam and tetracycline against A. baumannii were 88.0 and 100%, respectively. Very major errors for P. aeruginosa (resistant by the reference method, susceptible with the VITEK 2 system [resistant to susceptible]) were noted for cefepime (0.7%), cefotaxime (0.7%), gentamicin (0.7%), imipenem (1.4%), levofloxacin (2.7%), and piperacillin (2.7%) and, for one strain of A. baumannii, for imipenem. Major errors (susceptible to resistant) were noted only for P. aeruginosa and cefepime (2.0%), ceftazidime (0.7%), and piperacillin (3.4%). Minor errors ranged from 0.0% for piperacillin to 22.6% for cefotaxime against P. aeruginosa and from 0.0% for piperacillin and ciprofloxacin to 20.0% for cefepime against A. baumannii. The VITEK 2 system provided co-trimoxazole MICs only for S. maltophilia; no very major or major errors were obtained for co-trimoxazole against this species. It is concluded that the VITEK 2 system allows the rapid identification of S. maltophilia and most P. aeruginosa and A. baumannii isolates. The VITEK 2 system can perform reliable susceptibility testing of many of the antimicrobial agents used against P. aeruginosa and A. baumannii. It would be desirable if new versions of the VITEK 2 software were able to determine MICs and the corresponding clinical categories of agents active against S. maltophilia.
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Affiliation(s)
- P Joyanes
- Department of Microbiology, School of Medicine, University of Seville, Seville, Spain
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25
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Lubowski TJ, Woon JL, Hogan P, Hwang CC. Differences in antimicrobial susceptibility among hospitals in an integrated health system. Infect Control Hosp Epidemiol 2001; 22:379-82. [PMID: 11519918 DOI: 10.1086/501918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
We evaluated the differences in antimicrobial susceptibility among hospitals in three different integrated healthcare systems. Each system provided antibiogram-susceptibility reports from representative hospitals. Reports were analyzed for statistically significant differences between hospitals in a given system for nine important organisms. We found numerous significant interhospital differences in antimicrobial-susceptibility patterns within health systems. For this reason, the practice of combining antibiotic-susceptibility data into a systemwide antibiogram should be discouraged.
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Abstract
The authors discuss the latest findings regarding the use of one or more antimicrobial drugs for a variety of infections. They offer suggestions for treatment based on a host of considerations, including the synergy and antagonism of specific drugs, type of infection, potential toxicities, and cost.
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Affiliation(s)
- E Bouza
- Servicio de Microbiología Clínica y Enfermedades Infecciosas, Hospital General Universitario Gregorio Marañón, University of Madrid, Madrid, Spain.
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27
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Tsakris A, Pantazi A, Pournaras S, Maniatis A, Polyzou A, Sofianou D. Pseudo-outbreak of imipenem-resistant Acinetobacter baumannii resulting from false susceptibility testing by a rapid automated system. J Clin Microbiol 2000; 38:3505-7. [PMID: 10970417 PMCID: PMC87420 DOI: 10.1128/jcm.38.9.3505-3507.2000] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Introduction of the Vitek GNS-506 susceptibility testing cards in the Hippokration General Hospital, Thessaloniki, Greece, resulted in an apparently high prevalence of imipenem-resistant Acinetobacter baumannii. When 35 of these isolates were further tested by disk diffusion, broth microdilution, and agar dilution assays, 32 were imipenem sensitive by all tests and three were sensitive or intermediate, depending on the method. The pseudoresistant acinetobacters did not form a genetically homogeneous group. It is suggested that the detection of imipenem-resistant A. baumannii isolates by this system should be confirmed by an additional susceptibility test.
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Affiliation(s)
- A Tsakris
- Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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28
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Cantón R, Pérez-Vázquez M, Oliver A, Sánchez Del Saz B, Gutiérrez MO, Martínez-Ferrer M, Baquero F. Evaluation of the Wider system, a new computer-assisted image-processing device for bacterial identification and susceptibility testing. J Clin Microbiol 2000; 38:1339-46. [PMID: 10747104 PMCID: PMC86442 DOI: 10.1128/jcm.38.4.1339-1346.2000] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/1999] [Accepted: 01/10/2000] [Indexed: 11/20/2022] Open
Abstract
The Wider system is a newly developed computer-assisted image-processing device for both bacterial identification and antimicrobial susceptibility testing. It has been adapted to be able to read and interpret commercial MicroScan panels. Two hundred forty-four fresh consecutive clinical isolates (138 isolates of the family Enterobacteriaceae, 25 nonfermentative gram-negative rods [NFGNRs], and 81 gram-positive cocci) were tested. In addition, 100 enterobacterial strains with known beta-lactam resistance mechanisms (22 strains with chromosomal AmpC beta-lactamase, 8 strains with chromosomal class A beta-lactamase, 21 broad-spectrum and IRT beta-lactamase-producing strains, 41 extended-spectrum beta-lactamase-producing strains, and 8 permeability mutants) were tested. API galleries and National Committee for Clinical Laboratory Standards (NCCLS) microdilution methods were used as reference methods. The Wider system correctly identified 97.5% of the clinical isolates at the species level. Overall essential agreement (+/-1 log(2) dilution for 3,719 organism-antimicrobial drug combinations) was 95.6% (isolates of the family Enterobacteriaceae, 96.6%; NFGNRs, 88.0%; gram-positive cocci, 95.6%). The lowest essential agreement was observed with Enterobacteriaceae versus imipenem (84.0%), NFGNR versus piperacillin (88.0%) and cefepime (88.0%), and gram-positive isolates versus penicillin (80.4%). The category error rate (NCCLS criteria) was 4.2% (2.0% very major errors, 0.6% major errors, and 1. 5% minor errors). Essential agreement and interpretive error rates for eight beta-lactam antibiotics against isolates of the family Enterobacteriaceae with known beta-lactam resistance mechanisms were 94.8 and 5.4%, respectively. Interestingly, the very major error rate was only 0.8%. Minor errors (3.6%) were mainly observed with amoxicillin-clavulanate and cefepime against extended-spectrum beta-lactamase-producing isolates. The Wider system is a new reliable tool which applies the image-processing technology to the reading of commercial trays for both bacterial identification and susceptibility testing.
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Affiliation(s)
- R Cantón
- Servicio de Microbiología, Hospital Ramón y Cajal, Madrid 28034, Spain.
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29
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Zbinden R, von Graevenitz A, Rossi J, Kümin E, Berger-Bächi B, Hächler H, Nadal D. False-positive beta-lactamase results with Staphylococcus lugdunensis in the Vitek AutoMicrobic system. ZENTRALBLATT FUR BAKTERIOLOGIE : INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY 1999; 289:365-70. [PMID: 10467667 DOI: 10.1016/s0934-8840(99)80076-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The Vitek AutoMicrobic system in combination with the Gram-positive susceptibility card detects beta-lactamase in staphylococci by utilizing penicillin as the substrate coupled with oxacillin as an inducer. The beta-lactamase activity of 21 clinical isolates and two reference strains of Staphylococcus lugdunensis was determined with this automated system and compared with a liquid nitrocefin assay after induction with oxacillin. Eight (38%) clinical isolates and the reference strain ATCC 49576 of S. lugdunensis showed production of beta-lactamase in both tests. Thirteen (62%) clinical isolates and the type strain ATCC 43809 were nitrocefin-negative. The Vitek AutoMicrobic system reported false-positive beta-lactamase results for 9 of those 13 isolates and for the type strain of S. lugdunensis. Results for disk diffusion (ampicillin) were concordant with the nitrocefin assay. With one exception, the MICs for penicillin of the nitrocefin-negative strains were in the equivocal range of 0.06-0.12 mg/l according to NCCLS. However, none of the nitrocefin-negative and Vitek-positive strains revealed any of the known staphylococcal genes for beta-lactamase as investigated by Southern hybridization, supporting the fact that false-positive beta-lactamase results may occur in the Vitek AutoMicrobic system. We conclude from our data that it may be justified to include S. lugdunensis in the quality control of Vitek cards containing beta-lactamase tests.
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Affiliation(s)
- R Zbinden
- Department of Medical Microbiology, University of Zürich, Switzerland
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30
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Tang YW, Ellis NM, Hopkins MK, Smith DH, Dodge DE, Persing DH. Comparison of phenotypic and genotypic techniques for identification of unusual aerobic pathogenic gram-negative bacilli. J Clin Microbiol 1998; 36:3674-9. [PMID: 9817894 PMCID: PMC105261 DOI: 10.1128/jcm.36.12.3674-3679.1998] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rapid and accurate identification of bacterial pathogens is a fundamental goal of clinical microbiology, but one that is difficult or impossible for many slow-growing and fastidious organisms. We used identification systems based on cellular fatty acid profiles (Sherlock; MIDI, Inc., Newark, Del.), carbon source utilization (Microlog; Biolog, Inc., Hayward, Calif.), and 16S rRNA gene sequence (MicroSeq; Perkin-Elmer Applied Biosystems Division, Foster City, Calif.) to evaluate 72 unusual aerobic gram-negative bacilli isolated from clinical specimens at the Mayo Clinic. Compared to lengthy conventional methods, Sherlock, Microlog, and MicroSeq were able to identify 56 of 72 (77.8%), 63 of 72 (87.5%), and 70 of 72 (97.2%) isolates to the genus level (P = 0.002) and 44 to 65 (67.7%), 55 of 65 (84.6%), and 58 of 65 (89.2%) isolates to the species level (P = 0.005), respectively. Four Acinetobacter and three Bordetella isolates which could not be identified to the species level by conventional methods were identified by MicroSeq. In comparison to the full 16S rDNA sequences, the first 527 bp provided identical genus information for all 72 isolates and identical species information for 67 (93.1%) isolates. These data show that MicroSeq provides rapid, unambiguous identification of clinical bacterial isolates. The improved turnaround time provided by genotypic identification systems may translate into improved clinical outcomes.
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Affiliation(s)
- Y W Tang
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota 55905, USA
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