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Amer WH, Abd Elghafar MS, Abd-El-monsef MME. Comparison of Methods for Detecting Methicillin-Resistant Coagulase-Negative Staphylococci in Device-Associated Infections. ANTI-INFECTIVE AGENTS 2022; 20. [DOI: 10.2174/2211352519666210715150507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/07/2021] [Accepted: 06/22/2021] [Indexed: 09/01/2023]
Abstract
Background:
Coagulase-negative Staphylococci (CoNS) is one of the major causes of infections
in hospitals. Methicillin resistance has greatly increased in different CoNS species in previous
years. Here, we evaluated the performance of four phenotypic tests for detecting mecA-mediated
methicillin resistance rate in CoNS isolated from different device-associated infections in Tanta
University Hospitals, Egypt.
Methodology:
One hundred and fifteen CoNS isolates were examined for mecA-mediated methicillin
resistance using polymerase chain reaction (PCR) as the standard gold test. Susceptibility to
methicillin was investigated using VITEK 2 assay, oxacillin broth microdilution, and cefoxitin disc
diffusion tests.
Results:
Of all isolates, 98.3% were mecA-positive. The sensitivities of the different methods examined
were as follows: 100% for the VITEK cefoxitin test, 97.4% for the VITEK oxacillin test,
93.8% for the oxacillin broth microdilution, and 82.3% for the cefoxitin disc diffusion test. The test
specificity could not be accurately determined because of the small number of mecA-negative isolates
(n = 2).
Conclusion:
The rate of methicillin resistance reached 98.3% among CoNS isolates. Our results demonstrate
that the VITEK 2 assay is rapid and has high sensitivity compared to other phenotypic
methods for detecting methicillin resistance among different species of CoNS. Therefore, we recommend
the dual measurement of both cefoxitin and oxacillin susceptibilities using the VITEK 2
assay for best results.
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Affiliation(s)
- Wesam Hatem Amer
- Medical Microbiology and Immunology, Faculty of Medicine, Tanta University,Egypt
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2
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Direct detection of methicillin-resistant in Staphylococcus spp. in positive blood culture by isothermal recombinase polymerase amplification combined with lateral flow dipstick assay. World J Microbiol Biotechnol 2020; 36:162. [PMID: 32989593 DOI: 10.1007/s11274-020-02938-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/17/2020] [Indexed: 12/14/2022]
Abstract
Methicillin-resistant staphylococci (MRS) are important antimicrobial-resistant pathogens in sepsis. Conventional blood cultures take 24-72 h. The polymerase chain reaction (PCR)-based methods give faster results (2-3 h) but need expensive thermal cyclers. We therefore developed an isothermal recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD) assay for rapid detection of MRS in spiked blood culture samples. Fifty-six clinical isolates including 38 mecA-carrying staphylococci and 18 non-mecA-carrying organisms as confirmed by PCR methods were studied. RPA primer set and probe specific for mecA gene (encoding penicillin-binding protein 2a) were designed. RPA reaction was carried out under isothermal condition (45 °C) within 20 min and read by LFD in 5 min. The RPA-LFD provided 92.1% (35/38) sensitivity for identifying MRS in positive blood culture samples, and no cross-amplification was found (100% specificity). This test failed to detect three mecA-carrying S.sciuri isolates. The detection limits of RPA-LFD method for identifying MRS were equal to those of PCR method. The RPA-LFD is simple, fast, and user-friendly. This method could detect the mecA gene directly from the positive blood culture samples without requirement for special equipment. This method would be useful for appropriate antibiotic therapy and infection control, particularly in a low-resource setting.
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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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4
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Rapid differentiation of methicillin-resistant and methicillin-susceptible Staphylococcus aureus by flow cytometry after brief antibiotic exposure. J Clin Microbiol 2011; 49:2116-20. [PMID: 21471343 DOI: 10.1128/jcm.02548-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We noticed that methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) isolates yielded side-scatter (SSC) and fluorescence intensity (FI) differences on flow cytometry (FCM) following incubation in oxacillin broth. The purpose of this study was to determine whether MRSA and MSSA could be reliably differentiated by FCM. S. aureus isolates were incubated in oxacillin-containing Mueller-Hinton broth, stained using the FASTEST total viable organisms kit, and analyzed by FCM in the MicroPRO instrument. SSC versus FI were examined, and gates 1 and 2 were defined to encompass the majority of MSSA and MRSA signal events, respectively. A count ratio (CR) was defined as the ratio of counts in gate 2 to those in gate 1. Initially, 33 isolates were tested after 4 h of incubation for proof-of-concept. Twenty others were then tested after incubation intervals ranging from 30 min to 4 h to determine the earliest possible time for differentiation. Next, 100 separate isolates were tested to determine the best CR cutoff value. Finally, the CR was validated by using an independent cohort of 121 isolates. We noted that MRSA isolates had higher SSC and FI readings than did MSSA isolates after 2 h of incubation. The receiver-operator characteristics curve showed that a CR cutoff of 0.0445 reliably differentiated MRSA from MSSA. In the validation cohort, this cutoff had a sensitivity of 100% and a specificity of 98.7% for identifying MRSA from among S. aureus isolates, following 2 h of incubation. This study demonstrates that MRSA and MSSA can be accurately differentiated by FCM after 2 h of incubation in an oxacillin-containing liquid culture medium.
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Development of an immunochromatographic strip for simple detection of penicillin-binding protein 2'. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 18:248-53. [PMID: 21177917 DOI: 10.1128/cvi.00252-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Infections with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MR-CNS) are a serious problem in hospitals because these bacteria produce penicillin-binding protein 2' (PBP2' or PBP2a), which shows low affinity to β-lactam antibiotics. Furthermore, the bacteria show resistance to a variety of antibiotics. Identification of these pathogens has been carried out mainly by the oxacillin susceptibility test, which takes several days to produce a reliable result. We developed a simple immunochromatographic test that enabled the detection of PBP2' within about 20 min. Anti-PBP2' monoclonal antibodies were produced by a hybridoma of recombinant PBP2' (rPBP2')-immunized mouse spleen cells and myeloma cells. The monoclonal antibodies reacted only with PBP2' of whole-cell extracts and showed no detectable cross-reactivity with extracts from other bacterial species tested so far. One of the monoclonal antibodies was conjugated with gold colloid particles, which react with PBP2', and another antibody was immobilized on a nitrocellulose membrane, which captures the PBP2'-gold colloid particle complex on a nitrocellulose strip. This strip was able to detect 1.0 ng of rPBP2' or 2.8 × 10(5) to 1.7 × 10(7) CFU of MRSA cells. The cross-reactivity test using 15 bacterial species and a Candida albicans strain showed no detectable false-positive results. The accuracy of this method in the detection of MRSA and MR-CNS appeared to be 100%, compared with the results obtained by PCR amplification of the PBP2' gene, mecA. This newly developed immunochromatographic test can be used for simple and accurate detection of PBP2'-producing cells in clinical laboratories.
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6
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te Witt R, van Belkum A, van Leeuwen WB. Molecular diagnostics and genotyping of MRSA: an update. Expert Rev Mol Diagn 2010; 10:375-80. [PMID: 20465491 DOI: 10.1586/erm.10.34] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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7
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d'Azevedo PA, Trancesi R, Sales T, Monteiro J, Gales AC, Pignatari AC. Outbreak of Staphylococcus hominis subsp. novobiosepticus bloodstream infections in São Paulo city, Brazil. J Med Microbiol 2008; 57:256-257. [PMID: 18201999 DOI: 10.1099/jmm.0.47345-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Pedro A d'Azevedo
- Laboratório de Cocos Gram Positivos da Fundação Faculdade Federal de Ciências Médicas de Porto Alegre (FFFCMPA), RS, Brazil.,Laboratório Especial de Microbiologia Clínica (LEMC) da Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | - Regina Trancesi
- Comissão de Controle de Infecção do Hospital Nove de Julho, São Paulo, SP, Brazil
| | - Tiago Sales
- Laboratório Bioclínico, São Paulo, SP, Brazil
| | - Jussimara Monteiro
- Laboratório Especial de Microbiologia Clínica (LEMC) da Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | - Ana C Gales
- Laboratório Especial de Microbiologia Clínica (LEMC) da Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | - Antonio C Pignatari
- Comissão de Controle de Infecção do Hospital Nove de Julho, São Paulo, SP, Brazil.,Laboratório Especial de Microbiologia Clínica (LEMC) da Universidade Federal de São Paulo (UNIFESP), SP, Brazil
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8
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From clinical microbiology to infection pathogenesis: how daring to be different works for Staphylococcus lugdunensis. Clin Microbiol Rev 2008; 21:111-33. [PMID: 18202439 DOI: 10.1128/cmr.00036-07] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus lugdunensis has gained recognition as an atypically virulent pathogen with a unique microbiological and clinical profile. S. lugdunensis is coagulase negative due to the lack of production of secreted coagulase, but a membrane-bound form of the enzyme present in some isolates can result in misidentification of the organism as Staphylococcus aureus in the clinical microbiology laboratory. S. lugdunensis is a skin commensal and an infrequent pathogen compared to S. aureus and S. epidermidis, but clinically, infections caused by this organism resemble those caused by S. aureus rather than those caused by other coagulase-negative staphylococci. S. lugdunensis can cause acute and highly destructive cases of native valve endocarditis that often require surgical treatment in addition to antimicrobial therapy. Other types of S. lugdunensis infections include abscess and wound infection, urinary tract infection, and infection of intravascular catheters and other implanted medical devices. S. lugdunensis is generally susceptible to antimicrobial agents and shares CLSI antimicrobial susceptibility breakpoints with S. aureus. Virulence factors contributing to this organism's heightened pathogenicity remain largely unknown. Those characterized to date suggest that the organism has the ability to bind to and interact with host cells and to form biofilms on host tissues or prosthetic surfaces.
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10
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Palavecino E. Clinical, epidemiological, and laboratory aspects of methicillin-resistant Staphylococcus aureus (MRSA) infections. Methods Mol Biol 2007; 391:1-19. [PMID: 18025665 DOI: 10.1007/978-1-59745-468-1_1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen responsible for both hospital- and community-onset disease. Resistance to methicillin in S. aureus is mediated by PBP2a, a penicillin-binding protein with low affinity to beta-lactams, encoded by the mecA gene. Accurate susceptibility testing of S. aureus isolates and screening of patients for colonization with MRSA are important tools to limit the spread of this organism. This review focuses on the clinical significance of MRSA infections and new approaches for the laboratory diagnosis and epidemiological typing of MRSA strains.
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Affiliation(s)
- Elizabeth Palavecino
- Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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11
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Caierão J, Superti S, Dias CA, d'Azevedo PA. Automated systems in the identification and determination of methicillin resistance among coagulase negative staphylococci. Mem Inst Oswaldo Cruz 2006; 101:277-80. [PMID: 16862322 DOI: 10.1590/s0074-02762006000300009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Accepted: 04/18/2006] [Indexed: 11/21/2022] Open
Abstract
Coagulase-negative staphylococci (CoNS) are an important cause of nosocomial bacteremia, specially in patients with indwelling devices or those submitted to invasive medical procedures. The identification of species and the accurate and rapid detection of methicillin resistance are directly dependent on the quality of the identification and susceptibility tests used, either manual or automated. The objective of this study was to evaluate the accuracy of two automated systems--MicroScan and Vitek--in the identification of CoNS species and determination of susceptibility to methicillin, considering as gold standard the biochemical tests and the characterization of the mecA gene by polymerase chain reaction, respectively. MicroScan presented better results in the identification of CoNS species (accuracy of 96.8 vs 78.8%, respectively); isolates from the following species had no precise identification: Staphylococcus haemolyticus, S. simulans, and S. capitis. Both systems were similar in the characterization of methicillin resistance. The higher discrepancies for gene mec detection were observed among species other than S. epidermidis (S. hominis, S. saprophyticus, S. sciuri, S. haemolyticus, S. warneri, S. cohnii), and those with borderline MICs.
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Affiliation(s)
- Juliana Caierão
- Departamento de Microbiologia e Parasitologia, Fundacão Faculdade Federal de Ciêncas Médicas de Porto Alegre, Brasil
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Stepanović S, Hauschild T, Dakić I, Al-Doori Z, Svabić-Vlahović M, Ranin L, Morrison D. Evaluation of phenotypic and molecular methods for detection of oxacillin resistance in members of the Staphylococcus sciuri group. J Clin Microbiol 2006; 44:934-7. [PMID: 16517879 PMCID: PMC1393147 DOI: 10.1128/jcm.44.3.934-937.2006] [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] [Received: 10/25/2005] [Revised: 12/15/2005] [Accepted: 01/01/2006] [Indexed: 11/20/2022] Open
Abstract
In this paper we report on an experimental evaluation of phenotypic and molecular methods as means for the detection of oxacillin resistance in members of the Staphylococcus sciuri group. A total of 109 S. sciuri group member isolates (92 S. sciuri isolates, 9 S. lentus isolates, and 8 S. vitulinus isolates) were tested by the disk diffusion method, the agar dilution method, the oxacillin salt-agar screening method, slide latex agglutination for PBP 2a, and PCR assay for mecA as the reference method. The mecA gene was detected in 29 S. sciuri isolates, and the true-positive and true-negative results of the other tests were defined on the basis of the presence or the absence of the mecA gene. For the different methods evaluated, the sensitivities and specificities were as follows: for the disk diffusion test with a 1-microg oxacillin disk, 100% and 55.9%, respectively; for the disk diffusion test with a 30-mug cefoxitin disk, 93.5% and 100%, respectively; for the agar dilution method, 100% and 50%, respectively; for the oxacillin salt-agar screen test (with 6 microg of oxacillin per ml and 4% NaCl) 100% and 100%, respectively; and for the slide latex agglutination test for PBP 2a, 100% and 100%, respectively. The disk diffusion test with various beta-lactam antibiotics was performed to evaluate their use for the prediction of oxacillin resistance. The results indicate that meropenem, cefazolin, cefamandole, cefuroxime, cefotetan, cefoperazone, cefotaxime, ceftriaxone, moxalactam, cefaclor, and cefprozil may be used as surrogate markers of oxacillin resistance, although further studies of their use for the detection of oxacillin resistance are required.
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Affiliation(s)
- Srdjan Stepanović
- Department of Bacteriology, Institute of Microbiology and Immunology, School of Medicine, Dr Subotića 1, 11000 Belgrade, Serbia.
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Miller MB, Meyer H, Rogers E, Gilligan PH. Comparison of conventional susceptibility testing, penicillin-binding protein 2a latex agglutination testing, and mecA real-time PCR for detection of oxacillin resistance in Staphylococcus aureus and coagulase-negative Staphylococcus. J Clin Microbiol 2005; 43:3450-2. [PMID: 16000475 PMCID: PMC1169168 DOI: 10.1128/jcm.43.7.3450-3452.2005] [Citation(s) in RCA: 16] [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
Penicillin-binding protein (PBP) 2a latex agglutination was compared with conventional susceptibility testing and mecA real-time PCR for the detection of oxacillin resistance in Staphylococcus aureus. Inoculum volume and induction with oxacillin were PBP 2a testing variables. For coagulase-negative Staphylococcus, an increased inoculum volume of 10 microl greatly reduced the number of isolates requiring induction.
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Affiliation(s)
- Melissa B Miller
- University of North Carolina Hospitals, University of North Carolina School of Medicine, Campus Box 7525, Chapel Hill, NC 27599-7525, USA.
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Cretnik TZ, Vovko P, Retelj M, Jutersek B, Harlander T, Kolman J, Gubina M. Prevalence and nosocomial spread of methicillin-resistant Staphylococcus aureus in a long-term-care facility in Slovenia. Infect Control Hosp Epidemiol 2005; 26:184-90. [PMID: 15756890 DOI: 10.1086/502524] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To determine the prevalence and incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among residents and healthcare workers (HCWs) of a long-term-care facility (LTCF), to assess possible routes of nosocomial spread, and to determine genetic relatedness of the isolates. SETTING A 351-bed community LTCF for the elderly. DESIGN AND PARTICIPANTS Study investigators made two visits, approximately 3 months apart, to the facility. Samples for cultures were obtained from 107 residents during the first visit, 91 residents during the second visit, and 38 HCWs. RESULTS The prevalence of MRSA colonization among residents was 9.3% during the first visit and 8.8% during the second visit. During the first visit, two HCWs were colonized. During the second visit, no HCWs were colonized. The colonization of HCWs suggested a potential role in the transmission of MRSA. Molecular typing showed that two of three roommates in one room had the same strain, whereas two in another room differed from one another. All isolates, except one, belonged to two related clonal groups. It seems that the clonal group to which most isolates belonged had the greatest potential for spreading among both residents and HCWs. CONCLUSIONS Similar prevalence rates of MRSA colonization have been found in other European countries, but such studies have usually involved residents with better functional status than that of the participants in this study. Nosocomial spread of MRSA occurred in the facility examined, but not frequently. More attention should be focused on the hand hygiene of HCWs.
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Pottumarthy S, Schapiro JM, Prentice JL, Houze YB, Swanzy SR, Fang FC, Cookson BT. Clinical isolates of Staphylococcus intermedius masquerading as methicillin-resistant Staphylococcus aureus. J Clin Microbiol 2005; 42:5881-4. [PMID: 15583331 PMCID: PMC535261 DOI: 10.1128/jcm.42.12.5881-5884.2004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus intermedius is a zoonotic organism that can be associated with human disease. We report two separate cases of S. intermedius infection in which a false-positive rapid penicillin binding protein 2a latex test in conjunction with the phenotypic properties of beta-hemolysis and coagulase positivity allowed the clinical isolates to masquerade as methicillin-resistant Staphylococcus aureus. 16S rRNA gene sequencing and the absence of mecA revealed the strains to be methicillin-susceptible S. intermedius.
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Affiliation(s)
- Sudha Pottumarthy
- Department of Laboratory Medicine, University of Washington, 1959 NE Pacific St., Box 357110, Seattle, WA 98195, USA
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Horstkotte MA, Knobloch JKM, Rohde H, Dobinsky S, Mack D. Evaluation of the BD PHOENIX automated microbiology system for detection of methicillin resistance in coagulase-negative staphylococci. J Clin Microbiol 2005; 42:5041-6. [PMID: 15528693 PMCID: PMC525221 DOI: 10.1128/jcm.42.11.5041-5046.2004] [Citation(s) in RCA: 12] [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 new BD PHOENIX automated microbiology system (Becton Dickinson Diagnostic Systems, Sparks, Md.) is designed for automated rapid antimicrobial susceptibility testing and identification of clinically relevant bacteria. In our study, the accuracy and speed of the BD PHOENIX oxacillin MIC determination for detecting methicillin resistance was evaluated for 200 clinical isolates of coagulase-negative staphylococci (CoNS). Compared to mecA PCR, the BD PHOENIX system detected methicillin resistance with a sensitivity of 99.2%. According to the actual NCCLS oxacillin MIC breakpoint of > or =0.5 microg/ml, the specificity was only 64.9%, attributable to false-positive results in 26 mecA-negative strains, including 16 non-Staphylococcus epidermidis strains. Alternative oxacillin breakpoints of > or =1, > or =2, and > or =4 microg/ml resulted in increased specificities of 83.8, 94.6, and 100% and high sensitivities of 99.2, 99.2, and 96.7%, respectively. Similarly, NCCLS broth microdilution oxacillin MICs exhibited a sensitivity of 100% but a low degree of specificity. However, the previous oxacillin MIC breakpoint of > or =4 microg/ml performed with a sensitivity of 98.4% and a specificity of 98.7%. BD PHOENIX oxacillin MIC results were available after 9 h for 40.5% of the examined CoNS strains and were completed after 17 h. Our results revealed the high reliability of the BD PHOENIX system as a phenotypic method for detection of resistance to oxacillin in mecA-positive CoNS. However, for the improvement of specificity, reevaluation of the optimal oxacillin MIC breakpoint for CoNS appears to be necessary.
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Affiliation(s)
- Matthias A Horstkotte
- Institut für Infektionsmedizin, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany.
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Caierão J, Musskopf M, Superti S, Roesch E, Dias CG, d'Azevedo PA. Evaluation of phenotypic methods for methicillin resistance characterization in coagulase-negative staphylococci (CNS). J Med Microbiol 2004; 53:1195-1199. [PMID: 15585497 DOI: 10.1099/jmm.0.45697-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coagulase-negative staphylococci (CNS) are the major cause of nosocomial infections. Methicillin-resistant strains are particularly important because they narrow therapeutic options. Detecting methicillin resistance among CNS has been a challenge for years. The objective of this study was to determine the accuracy of an agar screening test (0.6 and 4 microg oxacillin ml(-1)), disc diffusion and the automated MicroScan system to characterize methicillin resistance among CNS. One hundred and seventy five strains were analysed: 41.1 % Staphylococcus epidermidis and 59.9 % other species; 69.1 % were mecA-positive. The results showed that the methods have optimal correlation with the detection of mecA gene for S. epidermidis, Staphylococcus hominis and Staphylococcus haemolyticus. However, accuracy of the tests is impaired when less common species are analysed. The only 100 % accurate test was agar screening with 4 microg oxacillin ml(-1).
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Affiliation(s)
- Juliana Caierão
- Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil
| | - Maiara Musskopf
- Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil
| | - Silvana Superti
- Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil
| | - Eliane Roesch
- Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil
| | - Cícero G Dias
- Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil
| | - Pedro A d'Azevedo
- Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil
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Corso A, Soloaga R, Faccone D, Gagetti P, Corbella S, Iglesias M, Galas M. Improvement of a latex agglutination test for the evaluation of oxacillin resistance in coagulase-negative staphylococci. Diagn Microbiol Infect Dis 2004; 50:223-5. [PMID: 15541610 DOI: 10.1016/j.diagmicrobio.2004.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Accepted: 06/04/2004] [Indexed: 10/26/2022]
Abstract
The "Slidex MRSA Detection" test (Denka Seiken, Japan) is a latex agglutination assay able to detect PBP2a. We evaluated its ability to differentiate mecA-positive from mecA-negative coagulase-negative staphylococci. We included 100 coagulase-negative staphylococci clinical isolates belonging to 9 species, 54 mecA positive and 46 mecA negative, as characterized by PCR. The specificity achieved using the manufacturer's instructions was 100%, but the sensitivity was only 57%. To increase sensitivity, we introduced modifications into the standard protocol. Using either large inocula or oxacillin induction before test performance, we achieved 100% sensitivity.
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Affiliation(s)
- A Corso
- Servicio Antimicrobianos, Departamento Bacteriología, Instituto Nacional de Enfermedades Infecciosas-ANLIS Dr. Carlos G. Malbrán, Buenos Aires, Argentina.
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19
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Ghoshal U, Prasad KN, Singh M, Tiwari DP, Ayyagari A. A comparative evaluation of phenotypic and molecular methods for the detection of oxacillin resistance in coagulase-negative staphylococci. J Infect Chemother 2004; 10:86-9. [PMID: 15160300 DOI: 10.1007/s10156-003-0293-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2003] [Accepted: 11/28/2003] [Indexed: 11/30/2022]
Abstract
Detection of oxacillin resistance in coagulase-negative staphylococci (C-NS) by phenotypic methods is often difficult. The present study compared the National Committee for Clinical Laboratory Standards (NCCLS) revised guidelines of phenotypic methods with a mecA-based polymerase chain reaction (PCR) for C-NS. Ninety clinical C-NS isolates were tested for oxacillin resistance by disk diffusion (1-microg disk), minimum inhibitory concentration (MIC) breakpoint (0.5 microg/ml) after 24 h, and mecA-based PCR. The sensitivity and specificity of disk diffusion was 80% and 93%, and the sensitivity and specificity of the MIC breakpoint after 24 h was 84% and 91%, respectively, against PCR as gold standard. Eleven strains (7 mecA-positive and 4 mecA-negative) showed discordant results between MIC breakpoint after 24 h and PCR. Six of the 7 mecA-positive and all 4 mecA-negative discordant strains had inducible oxacillin resistance and beta-lactamase hyperproduction, respectively. The present study concludes that inducible oxacillin resistance and beta-lactamase hyperproduction are the major causes of discordant results between phenotypic methods and mecA-based PCR, and need special attention.
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Affiliation(s)
- Ujjala Ghoshal
- Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226 014, India
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20
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Aïssa N, Stolar D, Legrand P. [Accuracy of four agar diffusion methods and the Vitek 2 automated system for the detection of the methicillin resistance in coagulase negative staphylococci]. ACTA ACUST UNITED AC 2004; 52:26-32. [PMID: 14761710 DOI: 10.1016/j.patbio.2003.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2002] [Accepted: 04/04/2003] [Indexed: 11/21/2022]
Abstract
AIM OF THE STUDY Technical difficulties may occur in the detection of methicillin resistance in coagulase negative staphylococci. Phenotypic methods, such as disk diffusion testing, sometimes fail to detect methicillin resistance because of its poor expression. Four of these methods were compared with the VITEK 2 system. MATERIALS AND METHODS The accuracy of the VITEK 2 system and the agar diffusion methods according to the current CASFM and NCCLS guidelines were assessed for methicillin susceptibility testing of 70 coagulase negative staphylococci isolates harboring the mecA gene for which the detection of the methicillin resistance was particularly difficult: the CASFM recommendations applied in 1998 failed to categorize them as methicillin-resistant. RESULTS Among the different methods currently suggested by the CASFM, those using a heavy inoculum and a hypersaline medium give better results, but they remain however less efficient than the NCCLS recommendations testing (sensitivity: 71-86% vs. 94-94% respectively). The VITEK 2 was more efficient (sensitivity: 91%) than the disk diffusion methods recommended by the CASFM and slightly less efficient than the method recommended by the NCCLS. CONCLUSION The VITEK 2 automated system, compared with the disk diffusion methods, showed adequate accuracy for detection of oxacillin resistance in coagulase negative staphylococci.
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Affiliation(s)
- N Aïssa
- Service de bactériologie-virologie-hygiène, hôpital Henri-Mondor, 51, avenue du Maréchal-de-Lattre-de-Tassigny, 94010 Créteil cedex, France
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21
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Spanu T, Sanguinetti M, D'Inzeo T, Ciccaglione D, Romano L, Leone F, Mazzella P, Fadda G. Identification of methicillin-resistant isolates of Staphylococcus aureus and coagulase-negative staphylococci responsible for bloodstream infections with the Phoenix™ system. Diagn Microbiol Infect Dis 2004; 48:221-7. [PMID: 15062913 DOI: 10.1016/j.diagmicrobio.2003.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Accepted: 11/17/2003] [Indexed: 11/24/2022]
Abstract
We evaluated the reliability of the new Phoenix system (Becton Dickinson Microbiology Systems, Sparks, Md.) in species-level identification and detection of oxacillin (methicillin) resistance among 493 staphylococcal isolates (Staphylococcus aureus, n = 223; coagulase-negative staphylococci, CoNS, n = 270) recovered from patients with bacteremia. Identification results were concordant with those of the ID 32 STAPH system (bioMérieux, Marcy l'Etoile, France) for 100% of S. aureus (223/223) and 97.4% (263/270) of CoNS isolates. For S. aureus isolates, Phoenix oxacillin-susceptibility results fully concurred with those of mecA polymerase chain reaction (PCR) (reference method): 96 mecA-positive isolates identified as resistant, 127 mecA-negative strains as susceptible. Two of the 210 mecA-positive CoNS isolates were misclassified as susceptible by the Phoenix (sensitivity 99%, positive predictive value 97.6%). Five of 60 mecA-negative CoNS isolates were classified as resistant by the Phoenix (specificity 91.7%; negative predictive value 96.5%). The Phoenix system can provide accurate and reliable identification of methicillin-resistant staphylococci responsible for bloodstream infections.
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Affiliation(s)
- Teresa Spanu
- Institute of Microbiology, Catholic University of the Sacred Heart, Rome, Italy.
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22
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Donay JL, Mathieu D, Fernandes P, Prégermain C, Bruel P, Wargnier A, Casin I, Weill FX, Lagrange PH, Herrmann JL. Evaluation of the automated phoenix system for potential routine use in the clinical microbiology laboratory. J Clin Microbiol 2004; 42:1542-6. [PMID: 15071001 PMCID: PMC387561 DOI: 10.1128/jcm.42.4.1542-1546.2004] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Revised: 09/01/2003] [Accepted: 01/07/2004] [Indexed: 11/20/2022] Open
Abstract
A comparative study was designed to evaluate the identification (ID) and antimicrobial susceptibility testing (AST) performances of the BD Phoenix Automated Microbiology System (Becton Dickinson Diagnostic Systems [BD], Pont de Claix, France). A total of 305 single clinical isolates were collected, and comparisons were made with routine manual methods in use in our microbiology laboratories. The percentages of correct IDs were 93.3, 89.4, 91.8, and 85.7% for enterobacteria, nonfermenting gram-negative bacilli, staphylococci, and streptococci-enterococci, respectively. The median ID time was 3 h, and the median time for AST was 10 h 30 min. AST results showed variable percentages of errors for the different antibiotics. None of the enterobacteria and 0.3% of Pseudomonas aeruginosa isolates showed a very major error (VME). Only one strain of Staphylococcus aureus showed a VME with oxacillin. We demonstrate here the efficiency of the Phoenix system, which can be used for the majority of strains encountered in a university-based laboratory, for ID and AST.
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Affiliation(s)
- J-L Donay
- Service de Microbiologie, Hôpital Saint Louis, Paris, France
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23
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Ebright JR, Penugonda N, Brown W. Clinical experience with Staphylococcus lugdunensis bacteremia: a retrospective analysis. Diagn Microbiol Infect Dis 2004; 48:17-21. [PMID: 14761717 DOI: 10.1016/j.diagmicrobio.2003.08.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Revised: 08/05/2003] [Indexed: 11/30/2022]
Abstract
We report a retrospective review of all cases of Staphylococcus lugdunensis bacteremia identified during a period of more than 10 years (January 1990 to May 2002) in a large medical center. Twenty-one cases occurred over that period; 20 cases were available for review. In six instances, the organism appeared to be clinically significant and was most commonly related to a vascular line infection. No deaths, secondary suppurative complications, prolonged bacteremia, or prolonged fever appeared to be caused by S. lugdunensis in our experience. Twenty-five percent of our isolates were resistant to multiple antibiotics, including oxacillin.
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Affiliation(s)
- John R Ebright
- Department of Medicine, Wayne State University School of Medicine, and Detroit Medical Center, Detroit, MI 48201, USA.
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24
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Horstkotte MA, Knobloch JKM, Rohde H, Dobinsky S, Mack D. Rapid detection of methicillin resistance in coagulase-negative Staphylococci with the VITEK 2 system. J Clin Microbiol 2002; 40:3291-5. [PMID: 12202568 PMCID: PMC130761 DOI: 10.1128/jcm.40.9.3291-3295.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Revised: 05/16/2002] [Accepted: 06/23/2002] [Indexed: 11/20/2022] Open
Abstract
The aim of the present study was to evaluate the accuracy of the new VITEK 2 system (bioMérieux, Marcy l' Etoile, France) for the detection of methicillin resistance in coagulase-negative staphylococci (CoNS) by using AST-P515 and AST-P523 test cards. Analyses of the VITEK 2 oxacillin MIC determination evaluated according to the actual breakpoint (>/=0.5 micro g/ml) of the National Committee for Clinical Laboratory Standards resulted in a high sensitivity of 99.2% but a moderate specificity of 80%. The newly included oxacillin resistance (OR) test of the VITEK 2 system displayed a high sensitivity and a high specificity of 97.5 and 98.7%, respectively. Concordance between the results of the mecA PCR and the VITEK 2 oxacillin MIC was observed for almost all Staphylococcus epidermidis strains, but the reduced specificity was attributable to higher oxacillin MICs for mecA-negative non-S. epidermidis strains, especially S. saprophyticus, S. lugdunensis, and S. cohnii. Evaluation of alternative oxacillin MIC breakpoints of 1, 2, or 4 micro g/ml resulted in improved degrees of specificity of 84, 90.7, and 97.3%, respectively. Only minor changes occurred in the corresponding sensitivity values, which were 98.4, 97.5, and 97.5%, respectively. Methicillin resistance in CoNS was detected after 7 and 8 h in 91.1 and 93.5% of the mecA-positive strains, respectively, by the VITEK 2 OR test and in 86.3 and 89.5% of the mecA-positive strains, respectively, by VITEK 2 oxacillin MIC determination. After 7 and 8 h the VITEK 2 OR test classified 59.2 and 78.9% of the mecA-negative strains, respectively, as susceptible to oxacillin, whereas comparable values were obtained 2 h later by VITEK 2 oxacillin MIC determination. The results of our study encourage the use of the VITEK 2 system, which proved to be a highly reliable and rapid phenotypic method for the detection of methicillin resistance in CoNS.
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Affiliation(s)
- Matthias A Horstkotte
- Institut für Medizinische Mikrobiologie und Immunologie, Universitätsklinikum Hamburg-Eppendorf, D-20246 Hamburg, Germany.
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Hussain Z, Stoakes L, John MA, Garrow S, Fitzgerald V. Detection of methicillin resistance in primary blood culture isolates of coagulase-negative staphylococci by PCR, slide agglutination, disk diffusion, and a commercial method. J Clin Microbiol 2002; 40:2251-3. [PMID: 12037101 PMCID: PMC130788 DOI: 10.1128/jcm.40.6.2251-2253.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The methicillin resistance of 363 coagulase-negative staphylococci isolated from blood cultures was determined by a slide latex agglutination (LA) test for penicillin-binding protein 2a (PBP 2a), the presence of the mecA gene by PCR, disk diffusion, and Vitek. LA was performed on primary cultures, and PBP 2a expression was induced by placing an oxacillin disk in the primary inoculum. Compared to the PCR results, LA was the most sensitive and specific in the detection of methicillin resistance. Without induction, LA failed to detect 50% of mecA-positive strains grown on two different media.
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Affiliation(s)
- Zafar Hussain
- Department of Microbiology and Infection Control, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada.
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26
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Woods W, Ramotar K, Lem P, Toye B. Oxacillin susceptibility testing of coagulase-negative staphylococci using the disk diffusion method and the Vitek GPS-105 card. Diagn Microbiol Infect Dis 2002; 42:291-4. [PMID: 12007449 DOI: 10.1016/s0732-8893(02)00365-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
One hundred and ninety-three isolates of coagulase-negative staphylococci (CoNS) were tested against oxacillin by agar dilution, disk diffusion, and Vitek (GPS-105 card), and the presence of the mecA gene determined by multiplex PCR. The results obtained by all testing methods were in agreement for 190 isolates. Two mecA-negative isolates (S. lugdunensis and S. haemolyticus) had MICs of < or = 0.25 microg/ml by agar dilution and Vitek but were resistant by disk diffusion. One mecA-positive isolate was resistant by Vitek and disk diffusion but had an agar dilution MIC of < or = 0.25 microg/ml. For the species of CoNS tested, oxacillin susceptibility results obtained with the Vitek GPS-105 card and disk diffusion correlated well with results obtained by National Committee for Clinical Laboratory Standards agar dilution and with the presence of the mecA gene.
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Affiliation(s)
- Wendi Woods
- Department of Pathology and Laboratory Medicine, The Ottawa Hospital, Ottawa, Ontario K1H 8L6, Canada
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