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Asgharzadeh M, Ozma MA, Rashedi J, Poor BM, Agharzadeh V, Vegari A, Shokouhi B, Ganbarov K, Ghalehlou NN, Leylabadlo HE, Kafil HS. False-Positive Mycobacterium tuberculosis Detection: Ways to Prevent Cross-Contamination. Tuberc Respir Dis (Seoul) 2020; 83:211-217. [PMID: 32578410 PMCID: PMC7362751 DOI: 10.4046/trd.2019.0087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/30/2020] [Accepted: 03/02/2020] [Indexed: 01/17/2023] Open
Abstract
The gold standard method for diagnosis of tuberculosis is the isolation of Mycobacterium tuberculosis through culture, but there is a probability of cross-contamination in simultaneous cultures of samples causing false-positives. This can result in delayed treatment of the underlying disease and drug side effects. In this paper, we reviewed studies on falsepositive cultures of M. tuberculosis. Rate of occurrence, effective factors, and extent of false-positives were analyzed. Ways to identify and reduce the false-positives and management of them are critical for all laboratories. In most cases, falsepositive is occurring in cases with only one positive culture but negative direct smear. The three most crucial factors in this regard are inappropriate technician function, contamination of reagents, and aerosol production. Thus, to reduce false-positives, good laboratory practice, as well as use of whole-genome sequencing or genotyping of all positive culture samples with a robust, extra pure method and rapid response, are essential for minimizing the rate of false-positives. Indeed, molecular approaches and epidemiological surveillance can provide a valuable tool besides culture to identify possible false positives.
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Affiliation(s)
- Mohammad Asgharzadeh
- Biotechnology Research Center, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mahdi Asghari Ozma
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Jalil Rashedi
- Tuberculosis and Lung Diseases Research Center, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behroz Mahdavi Poor
- Tuberculosis and Lung Diseases Research Center, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Vahid Agharzadeh
- Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Ali Vegari
- Department of Medical Physics, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Behrooz Shokouhi
- Connective Tissue Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | | | | | - Hossein Samadi Kafil
- Drug Applied Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
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2
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Barac A, Karimzadeh-Esfahani H, Pourostadi M, Rahimi MT, Ahmadpour E, Rashedi J, Mahdavipoor B, Kafil HS, Spotin A, Abate KH, Mathioudakis AG, Asgharzadeh M. Laboratory Cross-Contamination of Mycobacterium tuberculosis: A Systematic Review and Meta-analysis. Lung 2019; 197:651-661. [PMID: 31203380 DOI: 10.1007/s00408-019-00241-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/24/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND Microbiological cultures are the mainstay of the diagnosis of tuberculosis (TB). False-positive TB results lead to significant unnecessary therapeutic and economic burden and are frequently caused by laboratory cross-contamination. The aim of this meta-analysis was to quantify the prevalence of laboratory cross-contamination. METHODS Through a systematic review of five electronic databases, we identified studies reporting rates of laboratory cross-contamination, confirmed by molecular techniques in TB cultures. We evaluated the quality of the identified studies using the National Institute of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies, and conducted a meta-analysis using standard methodology recommended by the Cochrane Collaboration. RESULTS Based on 31 eligible studies evaluating 29,839 TB cultures, we found that 2% (95% confidence intervals [CI] 1-2%) of all positive TB cultures represent false-positive results secondary to laboratory cross-contamination. More importantly, we evaluated the rate of laboratory cross-contamination in cases where a single-positive TB culture was available in addition to at least one negative TB culture, and we found a rate of 15% (95% CI 6-33%). Moreover, 9.2% (91/990) of all patients with a preliminary diagnosis of TB had false-positive results and received unnecessary and potentially harmful treatments. CONCLUSIONS Our results highlight a remarkably high prevalence of false-positive TB results as a result of laboratory cross-contamination, especially in single-positive TB cultures, leading to the administration of unnecessary, harmful treatments. The need for the adoption of strict technical standards for mycobacterial cultures cannot be overstated.
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Affiliation(s)
- Aleksandra Barac
- Clinic for Infectious and Tropical Diseases, Clinical Centre of Serbia, Belgrade, Serbia.,Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | | | - Mahya Pourostadi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Ehsan Ahmadpour
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. .,Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Jalil Rashedi
- Tuberculosis and Lung Disease Research Center, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behroz Mahdavipoor
- Department of Laboratory Science, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Medical Parasitology, School of Medical Sciences, Tarbiat Modarres University, Tehran, Iran
| | - Hossein Samadi Kafil
- Department of Microbiology, Tabriz University of Medical Sciences, Tabriz, Iran.,Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Adel Spotin
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Alexander G Mathioudakis
- Division of Infection, Immunity and Respiratory Medicine, The University of Manchester, Manchester, UK. .,North West Lung Centre, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester, UK.
| | - Mohammad Asgharzadeh
- Faculty of Paramedicine, Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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3
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Methodological and Clinical Aspects of the Molecular Epidemiology of Mycobacterium tuberculosis and Other Mycobacteria. Clin Microbiol Rev 2016; 29:239-90. [PMID: 26912567 DOI: 10.1128/cmr.00055-15] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Molecular typing has revolutionized epidemiological studies of infectious diseases, including those of a mycobacterial etiology. With the advent of fingerprinting techniques, many traditional concepts regarding transmission, infectivity, or pathogenicity of mycobacterial bacilli have been revisited, and their conventional interpretations have been challenged. Since the mid-1990s, when the first typing methods were introduced, a plethora of other modalities have been proposed. So-called molecular epidemiology has become an essential subdiscipline of modern mycobacteriology. It serves as a resource for understanding the key issues in the epidemiology of tuberculosis and other mycobacterial diseases. Among these issues are disclosing sources of infection, quantifying recent transmission, identifying transmission links, discerning reinfection from relapse, tracking the geographic distribution and clonal expansion of specific strains, and exploring the genetic mechanisms underlying specific phenotypic traits, including virulence, organ tropism, transmissibility, or drug resistance. Since genotyping continues to unravel the biology of mycobacteria, it offers enormous promise in the fight against and prevention of the diseases caused by these pathogens. In this review, molecular typing methods for Mycobacterium tuberculosis and nontuberculous mycobacteria elaborated over the last 2 decades are summarized. The relevance of these methods to the epidemiological investigation, diagnosis, evolution, and control of mycobacterial diseases is discussed.
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4
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Laboratory cross-contamination of Mycobacterium tuberculosis in Northwest of Iran. EGYPTIAN JOURNAL OF CHEST DISEASES AND TUBERCULOSIS 2015. [DOI: 10.1016/j.ejcdt.2015.03.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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5
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Evaluation of low-colony-number counts of Mycobacterium tuberculosis on solid media as a microbiological marker of cross-contamination. J Clin Microbiol 2009; 47:1950-2. [PMID: 19357204 DOI: 10.1128/jcm.00626-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Low-colony-number counts on solid media are considered characteristic of cross-contamination, although they are normally observed in true-positive cultures from some groups of patients. The aim of this study was to evaluate low-yield growth cultures as a microbiological marker for cross-contamination. We evaluated 106 cultures with <15 colonies from 94 patients, and the proportions of false-positive cultures were 0.9% per sample and 1.1% per patient, which indicates that low-yield growth is not a reliable marker of cross-contamination.
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6
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Prodinger WM. Molecular epidemiology of tuberculosis: toy or tool? A review of the literature and examples from Central Europe. Wien Klin Wochenschr 2007; 119:80-9. [PMID: 17347855 DOI: 10.1007/s00508-006-0721-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Indexed: 11/28/2022]
Abstract
Genotyping has become an indispensable tool in medical microbiology and epidemiology. One of the first targets has been Mycobacterium tuberculosis. Over the past 15 years approximately 900 pertinent publications have substantiated the value of the genotyping approach for tuberculosis control. New insights into the understanding of the natural history of tuberculosis, especially regarding the frequencies of reactivation, reinfection or multiple infection entailed adaptations of pathophysiological concepts. However, assessment of recent transmission, outbreak analysis, and detection of laboratory contamination still form the genuine scope of genotyping. Detection of unsuspected clusters of cases can provide clues to search for further, undetected cases. Uncovering false positive cultures spares the risks and costs of unnecessary treatment and may reveal systematic laboratory weaknesses. Several European countries already profit from nationwide prospective fingerprinting. After providing genotyping results to public health officials, these were able to document epidemiological links for substantially more tuberculosis patients. On a global scale, strain families and particular strains have been identified, characterised and traced in their spread. The importation of Beijing-genotype multidrug-resistant M. tuberculosis into Central European countries will be described here as an example. The goal for further developments is the ability to compare isolates for epidemiological purposes in a single step that also comprises species determination, drug resistance testing and detection of pathogenicity factors.
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Affiliation(s)
- Wolfgang M Prodinger
- Division of Hygiene and Medical Microbiology, Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Innsbruck, Austria.
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7
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Rodrigues C, Almeida D, Shenai S, Goyal N, Mehta A. DEDICATED DECONTAMINATION: A NECESSITY TO PREVENT CROSS CONTAMINATION IN HIGH THROUGHPUT MYCOBACTERIOLOGY LABORATORIES. Indian J Med Microbiol 2007. [DOI: 10.1016/s0255-0857(21)02225-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Cook VJ, Stark G, Roscoe DL, Kwong A, Elwood RK. Investigation of suspected laboratory cross-contamination: interpretation of single smear-negative, positive cultures for Mycobacterium tuberculosis. Clin Microbiol Infect 2006; 12:1042-5. [PMID: 16961647 DOI: 10.1111/j.1469-0691.2006.01517.x] [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] [Indexed: 11/29/2022]
Abstract
Restriction fragment length polymorphism (RFLP) analysis can be used to assess genetic relatedness of Mycobacterium tuberculosis isolates. This study reports a collaborative investigation of false-positive cultures for M. tuberculosis, suspected when the DNA fingerprint from an index case matched an epidemiologically improbable source case. RFLP analysis matched fingerprints in ten of 16 cases of suspected laboratory contamination to four separate smear-positive sources that were processed on the same day in the same laboratory. All single smear-negative, positive cultures processed on the same day as smear-positive specimens should be reviewed on a case-by-case basis to identify possible false-positive cultures.
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Affiliation(s)
- V J Cook
- Division of TB Control, British Columbia Centre for Disease Control, Vancouver, Canada.
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9
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Mathema B, Kurepina NE, Bifani PJ, Kreiswirth BN. Molecular epidemiology of tuberculosis: current insights. Clin Microbiol Rev 2006; 19:658-85. [PMID: 17041139 PMCID: PMC1592690 DOI: 10.1128/cmr.00061-05] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular epidemiologic studies of tuberculosis (TB) have focused largely on utilizing molecular techniques to address short- and long-term epidemiologic questions, such as in outbreak investigations and in assessing the global dissemination of strains, respectively. This is done primarily by examining the extent of genetic diversity of clinical strains of Mycobacterium tuberculosis. When molecular methods are used in conjunction with classical epidemiology, their utility for TB control has been realized. For instance, molecular epidemiologic studies have added much-needed accuracy and precision in describing transmission dynamics, and they have facilitated investigation of previously unresolved issues, such as estimates of recent-versus-reactive disease and the extent of exogenous reinfection. In addition, there is mounting evidence to suggest that specific strains of M. tuberculosis belonging to discrete phylogenetic clusters (lineages) may differ in virulence, pathogenesis, and epidemiologic characteristics, all of which may significantly impact TB control and vaccine development strategies. Here, we review the current methods, concepts, and applications of molecular approaches used to better understand the epidemiology of TB.
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Affiliation(s)
- Barun Mathema
- Tuberculosis Center, Public Health Research Institute, Newark, NJ 07103, USA.
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Moore DAJ, Caviedes L, Gilman RH, Coronel J, Arenas F, LaChira D, Salazar C, Carlos Saravia J, Oberhelman RA, Hollm-Delgado MG, Escombe AR, Evans CAW, Friedland JS. Infrequent MODS TB culture cross-contamination in a high-burden resource-poor setting. Diagn Microbiol Infect Dis 2006; 56:35-43. [PMID: 16678991 PMCID: PMC2912514 DOI: 10.1016/j.diagmicrobio.2006.03.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 03/09/2006] [Accepted: 03/12/2006] [Indexed: 11/25/2022]
Abstract
One obstacle to wider use of rapid liquid culture-based tuberculosis diagnostics such as the microscopic observation drug susceptibility (MODS) assay is concern about cross-contamination. We investigated the rate of laboratory cross-contamination in MODS, automated MBBacT, and Lowenstein-Jensen (LJ) cultures performed in parallel, through triangulation of microbiologic (reculturing stored samples), molecular (spoligotype/RFLP), and clinical epidemiologic data. At least 1 culture was positive for Mycobacterium tuberculosis for 362 (11%) of 3416 samples; 53 were regarded as potential cross-contamination suspects. Cross-contamination accounted for 17 false-positive cultures from 14 samples representing 0.41% (14/3416) and 0.17% (17/10248) of samples and cultures, respectively. Positive predictive values for MODS, MBBacT (bioMérieux, Durham, NC), and LJ were 99.1%, 98.7%, and 99.7%, and specificity was 99.9% for all 3. Low rates of cross-contamination are achievable in mycobacterial laboratories in resource-poor settings even when a large proportion of samples are infectious and highly sensitive liquid culture-based diagnostics such as MODS are used.
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Affiliation(s)
- David A J Moore
- Department of Infectious Diseases and Immunity, Imperial College London Wellcome Centre for Clinical Tropical Medicine, W12 0NN London, UK.
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11
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Yan JJ, Jou R, Ko WC, Wu JJ, Yang ML, Chen HM. The use of variable-number tandem-repeat mycobacterial interspersed repetitive unit typing to identify laboratory cross-contamination with Mycobacterium tuberculosis. Diagn Microbiol Infect Dis 2005; 52:21-8. [PMID: 15878438 DOI: 10.1016/j.diagmicrobio.2004.12.002] [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] [Received: 05/18/2004] [Revised: 11/23/2004] [Indexed: 10/25/2022]
Abstract
A retrospective study including 515 Mycobacterium tuberculosis isolates from 215 patients was conducted to investigate possible laboratory contamination with M. tuberculosis over a 1-year period in a university hospital. All cultures underwent variable-number tandem-repeat (VNTR) typing. Cultures suspected of being contaminated in the VNTR analysis and possible sources of contamination underwent mycobacterial interspersed repetitive unit (MIRU) typing further. Overall, 8 (3.7%) cases of 215 patients were considered possible false-positives. Five (2.3%) cultures might be contaminated during initial batching processing, and 1 (0.5%) and 4 (1.9%) cultures of them were further classified as presumed and possible cases, respectively, of cross-contamination on clinical grounds. Three (1.4%) cultures might be contaminated by cultures that had been processed in species identification procedures in the same laminar-flow hood. The 2-step strategy using VNTR and MIRU analyses in combination in this study appears to be a valuable means for the study of false-positive cultures.
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Affiliation(s)
- Jing-Jou Yan
- Department of Pathology, National Cheng Kung University Hospital, Tainan 70428, Taiwan.
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12
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Haddad N, Masselot M, Durand B. Molecular differentiation of Mycobacterium bovis isolates. Review of main techniques and applications. Res Vet Sci 2004; 76:1-18. [PMID: 14659724 DOI: 10.1016/s0034-5288(03)00078-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Until recently, none of the Mycobacterium bovis typing techniques permitted a satisfactory differentiation of isolates. During the last 10 years, the genome of pathogenic mycobacteria has been extensively studied, and phylogenetic analyses have shown that all (except Mycobacterium avium) belong to a single genetic species: the Mycobacterium tuberculosis complex. This increase in knowledge about the genome of these bacteria has lead to the discovery of molecular markers that allow us to differentiate isolates. Because of the phylogenetic proximity of the strains, even if most of these markers have been discovered in M. tuberculosis, they could be successfully adapted to the other bacteria of the M. tuberculosis complex, especially M. bovis. The most common markers in use today are the IS6110 insertion sequence, the direct repeat (DR) region, the poly(GC) rich (PGRS) sequences and the variable number tandem repeats (VNTR) sequences. The corresponding typing techniques are briefly described, and current knowledge of polymorphism and marker stability is detailed. If molecular markers are to offer wide perspectives for field studies, these two characteristics (polymorphism and stability) must be taken into account when choosing the marker(s) used in a study. In this context, examples of the application of molecular typing techniques for M. bovis are reviewed, on the one hand with epidemiological studies for which the major problem is the comparison between isolates and, on the other, with more general studies about the population genetics of M. bovis in a given country, and about its history and its phylogeny.
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Affiliation(s)
- Nadia Haddad
- Ecole Nationale Vétérinaire, U.P. Maladies Contagieuses, Maisons-Alfort, France.
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Kanduma E, McHugh TD, Gillespie SH. Molecular methods for Mycobacterium tuberculosis strain typing: a users guide. J Appl Microbiol 2003; 94:781-91. [PMID: 12694442 DOI: 10.1046/j.1365-2672.2003.01918.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
There are now a wide range of techniques available to type Mycobacterium tuberculosis, the problem is to choose the correct technique. For large scale epidemiological studies the portability and standardization of IS6110 restriction fragment length polymorphism (RFLP) means that this remains the gold standard technique. In the next few years the internationally standard mycobacterial interspersed repetitive unit (MIRU) may come to challenge this primacy. Low copy number stains remain a problem and these can be typed by either polymorphic Guanine cytosine-rich repetitive sequence (PGRS) or MIRU-variable numbers of tandem repeat (VNTR). To confirm whether strains are part of a true cluster PGRS remains the method of choice. For local outbreaks and investigations of laboratory cross contamination where speed is of greatest importance suspect strains should be initially investigated using a PCR-based method. The superior reproducibility and discrimination of MIRU-VNTR means that these methods should be favoured. If matches are found, then further confirmation of identity can be achieved using IS6110 RFLP or PGRS if the strains prove to have a low IS6110 copy number.
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Affiliation(s)
- E Kanduma
- Clinical Laboratory, Kilimanjaro Christian Medical College, PO Box 3010, Moshi, Tanzania
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Tazi L, Kreiswirth B, Carrière C, Tibayrenc M. Molecular epidemiology of Mycobacterium tuberculosis and its relevance to the surveillance and control of TB: an e-debate. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2002; 2:153-8. [PMID: 12797993 DOI: 10.1016/s1567-1348(02)00132-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Loubna Tazi
- Genetics of Infectious Diseases, Unité mixte de Recherche Centre National de la Recherch Scientifique/Institut de Recherche pour le Développement no. 9926, IRD, BP 64501, 34394 Montpellier Cedex 5, France
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Abstract
Tuberculosis is an infectious disease caused by bacteria in the Mycobacterium tuberculosis complex. Of these, the most common species to infect humans is M. tuberculosis. The TB bacillus is an extremely successful human pathogen, infecting two billion persons worldwide; an estimated 2 to 3 million people die from tuberculosis each year. In the United States, TB rates decreased steadily at the rate of 5% per year from 1953 until 1985 when the trend reversed, with the number of TB cases peaking in 1992. Outbreaks of multidrug-resistant TB (MDR TB) were reported, and these cases were documented to be transmitted in nosocomial and congregate settings, including hospitals and prisons. AIDS patients infected with M. tb developed disease rapidly, and case-fatality rates of >80% were noted in those infected with multidrug-resistant M. tb. Intensive intervention, at enormous cost, caused the number of TB cases to decline. This article discusses factors that led to the increase in TB cases, their subsequent decline, and measures needed in the future if TB is to be eliminated in the United States.
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Affiliation(s)
- Parvathi Tiruviluamala
- New Jersey Medical School, National Tuberculosis Center, Newark, New Jersey 07107-3001, USA.
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16
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de Boer AS, Blommerde B, de Haas PEW, Sebek MMGG, Lambregts-van Weezenbeek KSB, Dessens M, van Soolingen D. False-positive mycobacterium tuberculosis cultures in 44 laboratories in The Netherlands (1993 to 2000): incidence, risk factors, and consequences. J Clin Microbiol 2002; 40:4004-9. [PMID: 12409366 PMCID: PMC139647 DOI: 10.1128/jcm.40.11.4004-4009.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
False-positive Mycobacterium tuberculosis cultures are a benchmark for the quality of laboratory processes and patient care. We studied the incidence of false-positive cultures, risk factors, and consequences for patients during the period from 1993 to 2000 in 44 peripheral laboratories in The Netherlands. The national reference laboratory tested 8,889 M. tuberculosis isolates submitted by these laboratories. By definition, a culture was false positive (i) if the DNA fingerprint of the isolate was identical to that of an isolate from another patient processed within 7 days in the same laboratory, (ii) if the isolate was taken from a patient without clinical signs of tuberculosis, and/or (iii) if the false-positive test result was confirmed by the peripheral laboratory and/or the public health tuberculosis officer. We identified 213 false-positive cultures (2.4%). The overall incidence of false-positive cultures decreased over the years, from 3.9% in 1993 to 1.1% in 2000. Laboratories with false-positive cultures more often processed less than 3,000 samples per year (P < 0.05). Among 110 patients for whom a false-positive culture was identified from 1995 to 1999, we found that for 36% of the patients an official tuberculosis notification had been provided to the appropriate public health services, 31% of the patients were treated, 14% of the patients were hospitalized, and a contact investigation had been initiated for 16% of the patients. The application of DNA fingerprinting to identify false-positive M. tuberculosis cultures and the provision of feedback to peripheral laboratories are useful instruments to improve the quality of laboratory processes and the quality of medical care.
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Affiliation(s)
- Annette S de Boer
- Center for Infectious Diseases Epidemiology, The Hague, The Netherlands.
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17
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Ruddy M, McHugh TD, Dale JW, Banerjee D, Maguire H, Wilson P, Drobniewski F, Butcher P, Gillespie SH. Estimation of the rate of unrecognized cross-contamination with mycobacterium tuberculosis in London microbiology laboratories. J Clin Microbiol 2002; 40:4100-4. [PMID: 12409381 PMCID: PMC139701 DOI: 10.1128/jcm.40.11.4100-4104.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Isolates from patients with confirmed tuberculosis from London were collected over 2.5 years between 1995 and 1997. Restriction fragment length polymorphism (RFLP) analysis was performed by the international standard technique as part of a multicenter epidemiological study. A total of 2,779 samples representing 2,500 individual patients from 56 laboratories were examined. Analysis of these samples revealed a laboratory cross-contamination rate of between 0.54%, when only presumed cases of cross-contamination were considered, and 0.93%, when presumed and possible cases were counted. Previous studies suggest an extremely wide range of laboratory cross-contamination rates of between 0.1 and 65%. These data indicate that laboratory cross-contamination has not been a common problem in routine practice in the London area, but in several incidents patients did receive full courses of therapy that were probably unnecessary.
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Affiliation(s)
- M Ruddy
- Department of Medical Microbiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom
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18
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Tudó G, González J, Gatell JM, Caylà JA, Martínez E, García A, Navarro M, Soriano E, Jiménez de Anta MT. Detection of unsuspected cases of nosocomial transmission of tuberculosis by use of a molecular typing method. Clin Infect Dis 2001; 33:453-9. [PMID: 11462179 DOI: 10.1086/322734] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2000] [Revised: 12/28/2000] [Indexed: 11/03/2022] Open
Abstract
The aim of this study was to use restriction fragment length polymorphism to detect unsuspected cases of nosocomial transmission of tuberculosis (TB) among patients who had been admitted to a university hospital. One hundred fifty-one samples of Mycobacterium tuberculosis isolated from patients with pulmonary TB were studied. The isolates from 37 patients (24.5%) defined 11 clusters. None of the patients infected with these cluster isolates had hospital stays that coincided with one another, and for 5.4% of the patients, the epidemiological link was clearly outside the hospital. Previous incarceration was associated with infection with cluster isolates. In addition, 109 patients without TB (41 of whom were infected with human immunodeficiency virus) who shared a room with patients who had TB were followed for 18-60 months. Among the patients who survived, secondary cases of TB due to nosocomial transmission were not detected.
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Affiliation(s)
- G Tudó
- Servei de Microbiologia, Institut Clínic d'Infeccions i Immunologia, Departament de Microbiologia i Parasitologia Sanitàries, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, E-08036 Barcelona, Spain
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Dahle UR, Sandven P, Heldal E, Caugant DA. Molecular epidemiology of Mycobacterium tuberculosis in Norway. J Clin Microbiol 2001; 39:1802-7. [PMID: 11325994 PMCID: PMC88029 DOI: 10.1128/jcm.39.5.1802-1807.2001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The incidence of tuberculosis in Norway is one of the lowest in the world, and approximately half of the cases occur in first- and second-generation immigrants. In the present study, the genetic diversity of 92% of all strains of Mycobacterium tuberculosis isolated in Norway in 1994 to 1998 was assessed using restriction fragment length polymorphism (RFLP) analysis, with the insertion sequence IS6110 and the repetitive element DR as probes, to determine the degree of active transmission between patients. The DR probe was used as a secondary molecular marker to support or rule out clustering of strains with fewer than five copies of IS6110. After exclusion of 20 cultures representing laboratory contamination, 573 different IS6110 patterns were found among the 698 strains analyzed. Of these 573 patterns, 542 were observed only once and 31 were shared by 2 to 14 isolates. Among 81 strains (11.5%) carrying fewer than five copies of IS6110, 56 RFLP patterns were found when the results of both the IS6110 and DR methods were combined. Among the 698 strains, 570 were considered to be independent cases. A total of 14.5% of the native Norwegians and 19.7% of the foreign patients were part of a cluster. Thus, the degree of recent transmission of tuberculosis in Norway is low and the great majority of the cases are due to reactivation of previous disease. Transmission between immigrants and native Norwegians is uncommon. Two outbreaks, one among native Norwegians and one mainly among immigrants, have been ongoing for several years, indicating that, even in a low-incidence country such as Norway, with a good national program for tuberculosis surveillance, certain transmission chains are difficult to break.
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Affiliation(s)
- U R Dahle
- Department of Bacteriology, National Institute of Public Health, N-0403 Oslo, Norway
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20
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Benjamin WH, Lok KH, Harris R, Brook N, Bond L, Mulcahy D, Robinson N, Pruitt V, Kirkpatrick DP, Kimerling ME, Dunlap NE. Identification of a contaminating Mycobacterium tuberculosis strain with a transposition of an IS6110 insertion element resulting in an altered spoligotype. J Clin Microbiol 2001; 39:1092-6. [PMID: 11230432 PMCID: PMC87878 DOI: 10.1128/jcm.37.3.1092-1096.2001] [Citation(s) in RCA: 14] [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
Molecular fingerprinting with the IS6110 insertion sequence is useful for tracking transmission of Mycobacterium tuberculosis within a population or confirming specimen contamination in the laboratory or through instrumentation. Secondary typing with other molecular methods yields additional information as to the relatedness of strains with similar IS6110 fingerprints. Isolated, relatively rare, random events within the M. tuberculosis genome alter molecular fingerprinting patterns with any of the methods; therefore, strains which are different by two or more typing methods are usually not considered to be closely related. In this report, we describe two strains of M. tuberculosis, obtained from the same bronchoscope 2 days apart, that demonstrated unique molecular fingerprinting patterns by two different typing methods. They were closely linked through the bronchoscope by a traditional epidemiologic investigation. Genetic analysis of the two strains revealed that a single event, the transposition of an IS6110 insertion sequence in one of the strains, accounted for both the differences in the IS6110 pattern and the apparent deletion of a spacer in the spoligotype. This finding shows that a single event can change the molecular fingerprint of a strain in two different molecular typing systems, and thus, molecular typing cannot be the only means used to track transmission of this organism through a population. Traditional epidemiologic techniques are a necessary complement to molecular fingerprinting so that radical changes within the fingerprint pattern can be identified.
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Affiliation(s)
- W H Benjamin
- The University of Alabama at Birmingham, Birmingham, AL 35294-0012, USA
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21
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Bifani P, Mathema B, Campo M, Moghazeh S, Nivin B, Shashkina E, Driscoll J, Munsiff SS, Frothingham R, Kreiswirth BN. Molecular identification of streptomycin monoresistant Mycobacterium tuberculosis related to multidrug-resistant W strain. Emerg Infect Dis 2001; 7:842-8. [PMID: 11747697 PMCID: PMC2631879 DOI: 10.3201/eid0705.010512] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
A distinct branch of the Mycobacterium tuberculosis W phylogenetic lineage (W14 group) has been identified and characterized by various genotyping techniques. The W14 group comprises three strain variants: W14, W23, and W26, which accounted for 26 clinical isolates from the New York City metropolitan area. The W14 group shares a unique IS6110 hybridizing banding motif as well as distinct polymorphic GC-rich repetitive sequence and variable number tandem repeat patterns. All W14 group members have high levels of streptomycin resistance. When the streptomycin resistance rpsL target gene was sequenced, all members of this strain family had an identical mutation in codon 43. Patients infected with the W14 group were primarily of non- Hispanic black origin (77%); all were US-born. Including HIV positivity, 84% of the patients had at least one known risk factor for tuberculosis.
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Affiliation(s)
- P Bifani
- Public Health Institute Tuberculosis Center, New York, NY 10016, USA
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22
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Van Soolingen D. Molecular epidemiology of tuberculosis and other mycobacterial infections: main methodologies and achievements. J Intern Med 2001; 249:1-26. [PMID: 11168781 DOI: 10.1046/j.1365-2796.2001.00772.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the last decade, DNA fingerprint techniques have become available to study the interperson transmission of tuberculosis and other mycobacterial infections. These methods have facilitated epidemiological studies at a population level. In addition, the species identification of rarely encountered mycobacteria has improved significantly. This article describes the state of the art of the main molecular typing methods for Mycobacterium tuberculosis complex and non-M. tuberculosis complex (atypical) mycobacteria. Important new insights that have been gained through molecular techniques into epidemiological aspects and diagnosis of mycobacterial diseases are highlighted.
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MESH Headings
- Animals
- Contact Tracing
- DNA Fingerprinting
- DNA, Bacterial/genetics
- Genetics, Microbial/trends
- Genotype
- Humans
- Molecular Epidemiology/methods
- Mycobacterium/classification
- Mycobacterium/genetics
- Mycobacterium/isolation & purification
- Mycobacterium Infections, Nontuberculous/epidemiology
- Mycobacterium Infections, Nontuberculous/genetics
- Mycobacterium Infections, Nontuberculous/transmission
- Mycobacterium tuberculosis/genetics
- Nontuberculous Mycobacteria/genetics
- Polymorphism, Restriction Fragment Length
- RNA, Bacterial/genetics
- Reproducibility of Results
- Sequence Analysis, DNA
- Sequence Analysis, RNA
- Transformation, Bacterial
- Tuberculosis/epidemiology
- Tuberculosis/genetics
- Tuberculosis/transmission
- Tuberculosis, Multidrug-Resistant/epidemiology
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Affiliation(s)
- D Van Soolingen
- Mycobacteria Reference Department, Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
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23
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Burman WJ, Reves RR. Review of false-positive cultures for Mycobacterium tuberculosis and recommendations for avoiding unnecessary treatment. Clin Infect Dis 2000; 31:1390-5. [PMID: 11096008 DOI: 10.1086/317504] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/1999] [Revised: 05/08/2000] [Indexed: 11/03/2022] Open
Abstract
We reviewed reports of false-positive cultures for Mycobacterium tuberculosis and here propose guidelines for detecting and managing patients with possible false-positive cultures. Mechanisms of false-positive cultures included contamination of clinical devices, clerical errors, and laboratory cross-contamination. False-positive cultures were identified in 13 (93%) of the 14 studies that evaluated > or = 100 patients; the median false-positive rate was 3.1% (interquartile range, 2.2%-10.5%). Of the 236 patients with false-positive cultures reported in sufficient detail, 158 (67%) were treated, some of whom had toxicity from therapy, as well as unnecessary hospitalizations, tests, and contact investigations. Having a single positive culture was a sensitive but nonspecific criterion for detecting false-positive cultures. False-positive cultures for M. tuberculosis are not rare but are infrequently recognized by laboratory and clinical personnel. Laboratories and tuberculosis control programs should develop procedures to identify patients having only 1 positive culture. Such patients should be further evaluated for the possibility of a false-positive culture.
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Affiliation(s)
- W J Burman
- Department of Public Health, Denver Health and Hospital Authority, CO, USA.
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24
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Sonnenberg P, Murray J, Shearer S, Glynn JR, Kambashi B, Godfrey-Faussett P. Tuberculosis treatment failure and drug resistance--same strain or reinfection? Trans R Soc Trop Med Hyg 2000; 94:603-7. [PMID: 11198641 DOI: 10.1016/s0035-9203(00)90205-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Tuberculosis patients may have Mycobacterium tuberculosis in their sputum at the end of treatment, and may show new drug resistance, due to either inadequate treatment of the original episode or reinfection with a new strain during therapy. In a cohort study of mineworkers with tuberculosis in South Africa, 57 of 438 patients had positive sputum cultures 6 months after recruitment in 1995. Of the 31 patients who initially had fully sensitive strains, 3 developed multidrug resistance (MDR) and 3 single-drug resistance (SDR). Of the 6 who started with SDR, 3 became MDR. HIV infection was not associated with drug resistance at enrollment or 6 months later. We compared pairs of DNA fingerprints from isolates of M. tuberculosis at recruitment and 6 months later in the 48 patients for whom we had both available. In 45, the pairs were identical. In 1 patient, although both isolates were fully sensitive, the later fingerprint had 1 less band (transposition). In 2 pairs, the fingerprint patterns were completely different: one seemed to be the result of laboratory error and the other was a true reinfection with an MDR strain. Despite a high risk of infection, with a moderate proportion of background drug-resistant strains (11% SDR, 6% MDR), reinfection is not a common cause of treatment failure or drug resistance at 6 months.
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Affiliation(s)
- P Sonnenberg
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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25
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Bifani P, Moghazeh S, Shopsin B, Driscoll J, Ravikovitch A, Kreiswirth BN. Molecular characterization of Mycobacterium tuberculosis H37Rv/Ra variants: distinguishing the mycobacterial laboratory strain. J Clin Microbiol 2000; 38:3200-4. [PMID: 10970357 PMCID: PMC87354 DOI: 10.1128/jcm.38.9.3200-3204.2000] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Mycobacterium tuberculosis strains H37Rv and H37Ra are the most commonly used controls for M. tuberculosis identification in the clinical and research laboratory setting. To reduce the likelihood of misidentification and possible cross-contamination with this laboratory neotype, it is important to be able to distinguish H37 from clinical isolates. To provide a reference for identifying H37, we used multiple molecular techniques to characterize H37 strains, including 18 of the most frequently used variants available through the American Type Culture Collection. Isolates were genotyped using gene probes to IS6110 and IS1085. In addition, we performed polymorphic GC-rich sequence typing (PGRS), spoligotyping, determination of variable number of tandem repeats (VNTR), and PCR amplification of the mtp40, msx4, and mpp8 polymorphic regions. Southern hybridization with IS6110 provided the most discrimination, differentiating the 18 H37 isolates into 10 discrete patterns made up of 9 H37Rv variants and 1 H37Ra variant. PGRS, IS1085, mpp8, and spoligotyping were not able to distinguish any H37 variants, while VNTR and msx4 discriminated two. Only IS6110 and spoligotyping could distinguish the H37 strain from clinical isolates. In summary, spoligotyping and IS6110 provide a rapid and accurate way to identify H37 contamination, though IS6110 can, in addition, classify many of the H37 variants that would otherwise require phenotypic segregation.
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Affiliation(s)
- P Bifani
- Public Health Research Institute Tuberculosis Center, New York University School of Medicine, New York, New York 10016, USA
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26
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Trakas K, Stosor V, Dietrich S, Mosher L, Warren JR. Persistent tuberculosis or specimen contamination? Arch Pathol Lab Med 2000; 124:902-3. [PMID: 10835532 DOI: 10.5858/2000-124-0902-ptosc] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cross-contamination during sequential processing of sputum specimens from different patients causes false-positive growth of Mycobacterium tuberculosis in culture. We describe an unusual case of cross-contamination in a 36-year-old man with acquired immunodeficiency syndrome and possible persistent tuberculosis. Culture with 1 of 3 sputum specimens was positive for rifampin-susceptible M tuberculosis. Review of processing revealed that his single culture-positive sputum specimen had followed a sputum specimen from another patient with active pulmonary tuberculosis that was positive in culture for M tuberculosis resistant to rifampin. Molecular strain typing by restriction fragment length polymorphism demonstrated the 2 isolates to be an identical strain of M tuberculosis. Agar proportion susceptibility testing of the rifampin-resistant isolate revealed low numbers of resistant organisms in a range of 1.5% to 3.3%. It was concluded that rifampin-susceptible organisms that constituted approximately 98% of the resistant isolate contaminated sputum from the patient with possible persistent tuberculosis. His culture result was, therefore, considered false positive, not an indication of tuberculosis.
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Affiliation(s)
- K Trakas
- Department of Pathology, Northwestern University Medical School, Chicago, IL 60611, USA
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27
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Park YK, Bai GH, Kim SJ. Restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolated from countries in the western pacific region. J Clin Microbiol 2000; 38:191-7. [PMID: 10618086 PMCID: PMC88694 DOI: 10.1128/jcm.38.1.191-197.2000] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A total of 422 Mycobacterium tuberculosis isolates from eight countries were subjected to IS6110 and IS1081 DNA fingerprinting by means of restriction fragment analysis to characterize M. tuberculosis strains from each country. Chinese, Mongolian, Hong Kong, Filipino, and Korean isolates had comparatively more copies of IS6110 (proportion with eight or more copies; 95% +/- 5%), while Thai, Malaysian, and Vietnamese isolates had fewer copies (proportion with eight or more copies, 60% +/- 4%). We found a number of novel IS1081 types in this study. One IS1081 type was present in 56% of Filipino isolates, had a specific 6.6-kb PvuII fragment in its IS6110 DNA fingerprint, and was termed the "Filipino family." The IS1081 types of Thai isolates had interposing characteristics between the characteristics of northeastern Asian and southeastern Asian IS1081 types. A 1.3-kb single-copy IS6110 fragment was found only in Vietnamese M. tuberculosis isolates. Although M. tuberculosis isolates from each country had comparatively similar characteristics depending on the classification factor, each country's isolates showed characteristic DNA fingerprints and differed slightly from the isolates from the other countries in either the mode number of IS6110 copies or the distribution of IS1081 types.
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Affiliation(s)
- Y K Park
- Korean Institute of Tuberculosis, Korean National Tuberculosis Association, Seoul, Korea
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28
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Bauer J, Andersen AB, Kremer K, Miörner H. Usefulness of spoligotyping To discriminate IS6110 low-copy-number Mycobacterium tuberculosis complex strains cultured in Denmark. J Clin Microbiol 1999; 37:2602-6. [PMID: 10405409 PMCID: PMC85294 DOI: 10.1128/jcm.37.8.2602-2606.1999] [Citation(s) in RCA: 82] [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
Mycobacterium tuberculosis complex strains cultured in Denmark have been analyzed by IS6110 restriction fragment length polymorphism (RFLP) on a routine basis from 1992 and onwards. Due to the influx of immigrants with tuberculosis, the number of strains harboring only one to five copies of IS6110 has increased steadily. Since the discriminatory power of IS6110 fingerprinting for such strains is poor, we have performed additional genotyping of all low-copy-number strains by the recently described PCR-based method known as spoligotyping. A total of 311 clinical strains were typed: 14 Mycobacterium bovis BCG, 48 M. bovis, and 249 M. tuberculosis strains. Spoligotyping correctly differentiated M. bovis and M. bovis BCG from M. tuberculosis strains, but it did not differentiate M. bovis from M. bovis BCG. All M. bovis BCG strains exhibited identical spoligotype patterns. The discriminatory power of spoligotyping of low-copy-number M. tuberculosis strains was higher than that of IS6110 fingerprinting. Based on RFLP typing solely, 83% of the low-copy-number M. tuberculosis strains were found to form part of a cluster, and 75% were found to form a cluster on the basis of spoligotyping. When the two techniques were combined, the amount of clustering decreased to 55%. The combination of these two techniques might be valuable in studying the epidemiology of M. tuberculosis strains harboring few copies of the IS6110 element.
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Affiliation(s)
- J Bauer
- Department of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.
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29
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de C Ramos M, Soini H, Roscanni GC, Jaques M, Villares MC, Musser JM. Extensive cross-contamination of specimens with Mycobacterium tuberculosis in a reference laboratory. J Clin Microbiol 1999; 37:916-9. [PMID: 10074501 PMCID: PMC88624 DOI: 10.1128/jcm.37.4.916-919.1999] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A striking increase in the numbers of cultures positive for Mycobacterium tuberculosis was noticed in a mycobacterial reference laboratory in Campinas, Sao Paulo State, Brazil, in May 1995. A contaminated bronchoscope was the suspected cause of the increase. All 91 M. tuberculosis isolates grown from samples from patients between 8 May and 18 July 1995 were characterized by spoligotyping and IS6110 fingerprinting. Sixty-one of the 91 isolates had identical spoligotype patterns, and the pattern was arbitrarily designated S36. The 61 specimens containing these isolates had been processed and cultured in a 21-day period ending on 1 June 1995, but only 1 sample was smear positive for acid-fast bacilli. The patient from whom this sample was obtained was considered to be the index case patient and had a 4+ smear-positive lymph node aspirate that had been sent to the laboratory on 10 May. Virtually all organisms with spoligotype S36 had the same IS6110 fingerprint pattern. Extensive review of the patients' charts and investigation of laboratory procedures revealed that cross-contamination of specimens had occurred. Because the same strain was grown from all types of specimens, the bronchoscope was ruled out as the outbreak source. The most likely source of contamination was a multiple-use reagent used for specimen processing. The organism was cultured from two of the solutions 3 weeks after mock contamination. This investigation strongly supports the idea that M. tuberculosis grown from smear-negative specimens should be analyzed by rapid and reliable strain differentiation techniques, such as spoligotyping, to help rule out laboratory contamination.
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Affiliation(s)
- M de C Ramos
- Faculdade de Ciencias Medicas, Universidade Estadual de Campinas (UNICAMP), Campinas, Sao Paulo State, Brazil
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30
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Gutiérrez MC, Vincent V, Aubert D, Bizet J, Gaillot O, Lebrun L, Le Pendeven C, Le Pennec MP, Mathieu D, Offredo C, Pangon B, Pierre-Audigier C. Molecular fingerprinting of Mycobacterium tuberculosis and risk factors for tuberculosis transmission in Paris, France, and surrounding area. J Clin Microbiol 1998; 36:486-92. [PMID: 9466764 PMCID: PMC104565 DOI: 10.1128/jcm.36.2.486-492.1998] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Forty-three percent of the tuberculosis cases reported in France are from the Ile de France region. The incidence of tuberculosis in this region is 33 cases per 100,000 inhabitants, twice the national average. A restriction fragment length polymorphism (RFLP) analysis was performed with clinical isolates of Mycobacterium tuberculosis isolated during 1995 in 10 hospitals in Paris and surrounding areas to detect tuberculosis transmission and define the factors associated with clustering in this population. The molecular markers used were the insertion sequence IS6110 and the direct repeat (DR) sequence. Social, demographic, and clinical data were collected from the patients' medical files. Ten patients with isolates with a single copy of IS6110 were excluded from further analysis. Twenty-four patients with false-positive cultures due to laboratory contamination (based on RFLP analysis with IS6110 and examination of patient data) were also excluded. The study was then conducted with 272 strains isolated from 272 patients. Further fingerprinting was performed by using the DR element with strains with patterns by RFLP analysis with IS6110 that differed by one band only and strains with identical patterns by RFLP analysis with IS6110 and with low numbers of copies of IS6110. The combined use of both markers identified unique patterns for 177 strains and clustered 95 (35.7%) strains in 26 groups, each containing isolates from 2 to 12 patients. The clustering was strongly associated with homelessness and the male sex. It was not associated with age, birth in a foreign country, human immunodeficiency virus positivity, or residence in hostels or prison. Isolates from homeless people were often included in large clusters, and homeless people could be the source of tuberculosis transmission for more than 50% of the clustered patients. These results suggest that homeless people play a key role in the spread of M. tuberculosis in the community and that poor socioeconomic conditions are the main risk factors associated with active tuberculosis transmission.
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Affiliation(s)
- M C Gutiérrez
- Centre National de Référence des Mycobactéries, Institut Pasteur, Paris, France
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31
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Bauer J, Yang Z, Poulsen S, Andersen AB. Results from 5 years of nationwide DNA fingerprinting of Mycobacterium tuberculosis complex isolates in a country with a low incidence of M. tuberculosis infection. J Clin Microbiol 1998; 36:305-8. [PMID: 9431975 PMCID: PMC124862 DOI: 10.1128/jcm.36.1.305-308.1998] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Results from DNA fingerprint analyses of Mycobacterium tuberculosis complex isolates from tuberculosis (TB) patients diagnosed during 5 years in Denmark are presented. The lack of success in eradicating TB in this low-incidence country may be explained by an unrecognized high frequency of active TB transmission (57%) among native Danes. Only two strains of M. tuberculosis are responsible for 40% of all clustered cases of TB among Danes.
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Affiliation(s)
- J Bauer
- Department of Mycobacteriology, Statens Serum Institut, Copenhagen S, Denmark.
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