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Performance and Application of 16S rRNA Gene Cycle Sequencing for Routine Identification of Bacteria in the Clinical Microbiology Laboratory. Clin Microbiol Rev 2020; 33:33/4/e00053-19. [PMID: 32907806 DOI: 10.1128/cmr.00053-19] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This review provides a state-of-the-art description of the performance of Sanger cycle sequencing of the 16S rRNA gene for routine identification of bacteria in the clinical microbiology laboratory. A detailed description of the technology and current methodology is outlined with a major focus on proper data analyses and interpretation of sequences. The remainder of the article is focused on a comprehensive evaluation of the application of this method for identification of bacterial pathogens based on analyses of 16S multialignment sequences. In particular, the existing limitations of similarity within 16S for genus- and species-level differentiation of clinically relevant pathogens and the lack of sequence data currently available in public databases is highlighted. A multiyear experience is described of a large regional clinical microbiology service with direct 16S broad-range PCR followed by cycle sequencing for direct detection of pathogens in appropriate clinical samples. The ability of proteomics (matrix-assisted desorption ionization-time of flight) versus 16S sequencing for bacterial identification and genotyping is compared. Finally, the potential for whole-genome analysis by next-generation sequencing (NGS) to replace 16S sequencing for routine diagnostic use is presented for several applications, including the barriers that must be overcome to fully implement newer genomic methods in clinical microbiology. A future challenge for large clinical, reference, and research laboratories, as well as for industry, will be the translation of vast amounts of accrued NGS microbial data into convenient algorithm testing schemes for various applications (i.e., microbial identification, genotyping, and metagenomics and microbiome analyses) so that clinically relevant information can be reported to physicians in a format that is understood and actionable. These challenges will not be faced by clinical microbiologists alone but by every scientist involved in a domain where natural diversity of genes and gene sequences plays a critical role in disease, health, pathogenicity, epidemiology, and other aspects of life-forms. Overcoming these challenges will require global multidisciplinary efforts across fields that do not normally interact with the clinical arena to make vast amounts of sequencing data clinically interpretable and actionable at the bedside.
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Apoptosis Functions in Defense against Infection of Mammalian Cells with Environmental Chlamydiae. Infect Immun 2020; 88:IAI.00851-19. [PMID: 32179584 DOI: 10.1128/iai.00851-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/26/2020] [Indexed: 01/09/2023] Open
Abstract
Apoptotic cell death can be an efficient defense reaction of mammalian cells infected with obligate intracellular pathogens; the host cell dies and the pathogen cannot replicate. While this is well established for viruses, there is little experimental support for such a concept in bacterial infections. All Chlamydiales are obligate intracellular bacteria, and different species infect vastly different hosts. Chlamydia trachomatis infects human epithelial cells; Parachlamydia acanthamoebae replicates in amoebae. We here report that apoptosis impedes growth of P. acanthamoebae in mammalian cells. In HeLa human epithelial cells, P. acanthamoebae infection induced apoptosis, which was inhibited when mitochondrial apoptosis was blocked by codeletion of the mediators of mitochondrial apoptosis, Bax and Bak, by overexpression of Bcl-XL or by deletion of the apoptosis initiator Noxa. Deletion of Bax and Bak in mouse macrophages also inhibited apoptosis. Blocking apoptosis permitted growth of P. acanthamoebae in HeLa cells, as measured by fluorescence in situ hybridization, assessment of genome replication and protein synthesis, and the generation of infectious progeny. Coinfection with C. trachomatis inhibited P. acanthamoebae-induced apoptosis, suggesting that the known antiapoptotic activity of C. trachomatis can also block P. acanthamoebae-induced apoptosis. C. trachomatis coinfection could not rescue P. acanthamoebae growth in HeLa; in coinfected cells, C. trachomatis even suppressed the growth of P. acanthamoebae independently of apoptosis, while P. acanthamoebae surprisingly enhanced the growth of C. trachomatis Our results show that apoptosis can be used in the defense of mammalian cells against obligate intracellular bacteria and suggest that the known antiapoptotic activity of human pathogenic chlamydiae is indeed required to permit their growth in human cells.
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Deepthi KG, Prabagaran SR. Ocular bacterial infections: Pathogenesis and diagnosis. Microb Pathog 2020; 145:104206. [PMID: 32330515 DOI: 10.1016/j.micpath.2020.104206] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 12/19/2022]
Abstract
The human eye is a rigid asymmetric structure with unique defence system. Despite considerable resident microbiota, eye is exposed to external environment where a range of microorganisms also inhabits. Opportunistically, some of these microorganisms could associate with eye pathogen that could contact incidentally, leading to destructive visual consequences. Among such microbiota, bacteria form the major proportion concerning ocular complications worldwide. The succession of genome based approach through 16S rRNA gene based identification tremendously augmented the knowledge on diversity of ocular surface bacteria. Such evidence suggests that while few bacteria contribute towards normal ocular functions, considerable number of bacteria play active role in pathophysiology of ocular diseases. Thus, understanding the complexity of ocular microflora not only throw light on their critical role towards normal function of the eye, but also enlighten on certain visual exigencies. Under these circumstances, development of a rapid, reliable and cost effective method is essential that eventually evolve as a routine diagnostic protocol. Such precise prognostic modalities facilitate ophthalmologists to formulate pioneering therapeutics towards challenging ocular diseases.
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Brokatzky D, Dörflinger B, Haimovici A, Weber A, Kirschnek S, Vier J, Metz A, Henschel J, Steinfeldt T, Gentle IE, Häcker G. A non-death function of the mitochondrial apoptosis apparatus in immunity. EMBO J 2019; 38:embj.2018100907. [PMID: 30979778 DOI: 10.15252/embj.2018100907] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/15/2019] [Accepted: 03/21/2019] [Indexed: 12/22/2022] Open
Abstract
Apoptosis is a frequent form of programmed cell death, but the apoptotic signaling pathway can also be engaged at a low level, in the absence of cell death. We here report that such sub-lethal engagement of mitochondrial apoptosis signaling causes the secretion of cytokines from human epithelial cells in a process controlled by the Bcl-2 family of proteins. We further show that sub-lethal signaling of the mitochondrial apoptosis pathway is initiated by infections with all tested viral, bacterial, and protozoan pathogens and causes damage to the genomic DNA. Epithelial cells infected with these pathogens secreted cytokines, and this cytokine secretion upon microbial infection was substantially reduced if mitochondrial sub-lethal apoptosis signaling was blocked. In the absence of mitochondrial pro-apoptotic signaling, the ability of epithelial cells to restrict intracellular bacterial growth was impaired. Triggering of the mitochondrial apoptosis apparatus thus not only causes apoptosis but also has an independent role in immune defense.
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Affiliation(s)
- Dominik Brokatzky
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Benedikt Dörflinger
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Aladin Haimovici
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Arnim Weber
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Susanne Kirschnek
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Juliane Vier
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Arlena Metz
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Julia Henschel
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Tobias Steinfeldt
- Faculty of Medicine, Institute of Virology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Ian E Gentle
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany
| | - Georg Häcker
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center, University of Freiburg, Freiburg, Germany .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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Joseph SJ, Marti H, Didelot X, Read TD, Dean D. Tetracycline Selective Pressure and Homologous Recombination Shape the Evolution of Chlamydia suis: A Recently Identified Zoonotic Pathogen. Genome Biol Evol 2016; 8:2613-23. [PMID: 27576537 PMCID: PMC5010913 DOI: 10.1093/gbe/evw182] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2016] [Indexed: 12/22/2022] Open
Abstract
Species closely related to the human pathogen Chlamydia trachomatis (Ct) have recently been found to cause zoonotic infections, posing a public health threat especially in the case of tetracycline resistant Chlamydia suis (Cs) strains. These strains acquired a tet(C)-containing cassette via horizontal gene transfer (HGT). Genomes of 11 Cs strains from various tissues were sequenced to reconstruct evolutionary pathway(s) for tet(C) HGT. Cs had the highest recombination rate of Chlamydia species studied to date. Admixture occurred among Cs strains and with Chlamydia muridarum but not with Ct Although in vitro tet(C) cassette exchange with Ct has been documented, in vivo evidence may require examining human samples from Ct and Cs co-infected sites. Molecular-clock dating indicated that ancestral clades of resistant Cs strains predated the 1947 discovery of tetracycline, which was subsequently used in animal feed. The cassette likely spread throughout Cs strains by homologous recombination after acquisition from an external source, and our analysis suggests Betaproteobacteria as the origin. Selective pressure from tetracycline may be responsible for recent bottlenecks in Cs populations. Since tetracycline is an important antibiotic for treating Ct, zoonotic infections at mutual sites of infection indicate the possibility for cassette transfer and major public health repercussions.
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Affiliation(s)
- Sandeep J Joseph
- Department of Medicine, Division of Infectious Diseases and Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Hanna Marti
- Center for Immunobiology and Vaccine Development, UCSF Benioff Children's Hospital Oakland Research Institute, Oakland, CA, USA
| | - Xavier Didelot
- Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Timothy D Read
- Department of Medicine, Division of Infectious Diseases and Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Deborah Dean
- Center for Immunobiology and Vaccine Development, UCSF Benioff Children's Hospital Oakland Research Institute, Oakland, CA, USA Joint Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
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Buchacher T, Ohradanova-Repic A, Stockinger H, Fischer MB, Weber V. M2 Polarization of Human Macrophages Favors Survival of the Intracellular Pathogen Chlamydia pneumoniae. PLoS One 2015; 10:e0143593. [PMID: 26606059 PMCID: PMC4659546 DOI: 10.1371/journal.pone.0143593] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 11/06/2015] [Indexed: 12/12/2022] Open
Abstract
Intracellular pathogens have developed various strategies to escape immunity to enable their survival in host cells, and many bacterial pathogens preferentially reside inside macrophages, using diverse mechanisms to penetrate their defenses and to exploit their high degree of metabolic diversity and plasticity. Here, we characterized the interactions of the intracellular pathogen Chlamydia pneumoniae with polarized human macrophages. Primary human monocytes were pre-differentiated with granulocyte macrophage colony-stimulating factor or macrophage colony-stimulating factor for 7 days to yield M1-like and M2-like macrophages, which were further treated with interferon-γ and lipopolysaccharide or with interleukin-4 for 48 h to obtain fully polarized M1 and M2 macrophages. M1 and M2 cells exhibited distinct morphology with round or spindle-shaped appearance for M1 and M2, respectively, distinct surface marker profiles, as well as different cytokine and chemokine secretion. Macrophage polarization did not influence uptake of C. pneumoniae, since comparable copy numbers of chlamydial DNA were detected in M1 and M2 at 6 h post infection, but an increase in chlamydial DNA over time indicating proliferation was only observed in M2. Accordingly, 72±5% of M2 vs. 48±7% of M1 stained positive for chlamydial lipopolysaccharide, with large perinuclear inclusions in M2 and less clearly bordered inclusions for M1. Viable C. pneumoniae was present in lysates from M2, but not from M1 macrophages. The ability of M1 to restrict chlamydial replication was not observed in M1-like macrophages, since chlamydial load showed an equal increase over time for M1-like and M2-like macrophages. Our findings support the importance of macrophage polarization for the control of intracellular infection, and show that M2 are the preferred survival niche for C. pneumoniae. M1 did not allow for chlamydial proliferation, but failed to completely eliminate chlamydial infection, giving further evidence for the ability of C. pneumoniae to evade cellular defense and to persist in human macrophages.
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Affiliation(s)
- Tanja Buchacher
- Christian Doppler Laboratory for Innovative Therapy Approaches in Sepsis, Danube University Krems, Krems, Austria
| | - Anna Ohradanova-Repic
- Molecular Immunology Unit, Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Hannes Stockinger
- Molecular Immunology Unit, Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Michael B. Fischer
- Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria
- Department for Health Sciences and Biomedicine, Danube University Krems, Krems, Austria
| | - Viktoria Weber
- Christian Doppler Laboratory for Innovative Therapy Approaches in Sepsis, Danube University Krems, Krems, Austria
- Department for Health Sciences and Biomedicine, Danube University Krems, Krems, Austria
- * E-mail:
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Gillissen A, Paparoupa M. Inflammation and infections in asthma. THE CLINICAL RESPIRATORY JOURNAL 2015; 9:257-69. [PMID: 24725460 PMCID: PMC7162380 DOI: 10.1111/crj.12135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 04/26/2014] [Accepted: 04/04/2014] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Asthma is driven by an inflammatory response against normally harmless environmental inorganic and organic compounds in the respiratory tract. Immune responses to airborne pathogens such as viruses and bacteria may reduce the allergic responses but are also known to trigger asthma attacks and eventually lead to severe disease condition. OBJECTIVE To investigate the role of respiratory pathogens concerning the induction or protection against acute or chronic asthma manifestations. METHODS We included 131 articles for the final review according to their relevance with the subject. RESULTS There is apparently contradictory interaction of respiratory germs in the airways of asthmatics which may be protective on one angle but deleterious on the other. CONCLUSION The relationship between inflammation and remodeling and the pathogenic role of viral and bacterial infection in the airways of asthmatic patients is still highly debatable and incompletely understood.
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Affiliation(s)
- Adrian Gillissen
- Department of Pulmonary MedicineGeneral Hospital KasselKasselGermany
| | - Maria Paparoupa
- Department of Pulmonary MedicineGeneral Hospital KasselKasselGermany
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Goldschmidt P. Social Sciences for the Prevention of Blindness. Trop Med Health 2015; 43:141-8. [PMID: 26161032 PMCID: PMC4491490 DOI: 10.2149/tmh.2014-32] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 03/19/2015] [Indexed: 11/11/2022] Open
Abstract
Organizations working for the elimination of Chlamydia-triggered blindness (trachoma) follow the WHO SAFE strategy (surgery for trichiasis, antibiotics, face washing and environmental changes) with the aim to achieve a minimum of 80% of children with clean faces in endemic communities, mass treatment covering the whole district with trachoma rates of 10% or more and surveillance plans. Trachoma recurrence that is common after implementing the SAFE strategy 3, 5 or even 7 times evidence that the cognitive processes requiring assimilation and integration of knowledge did not register with parents, caretakers and children. Moreover, repeated awareness campaigns to improve hygiene did not systematically produce irreversible changes of behavior in neglected populations. In view of this evidence, the rational behind mass drug administration as the mainstay of preventable blindness elimination demands a wider scope than simple mathematical models. The reluctance to see disappointing outcomes that leads to repeated interventions may suggest from a sociologic point of view that the strategies are products of those evaluating the activities of those who fund them and vice versa. A similar articulation emerges for reciprocal interactions between researchers and those judging the pertinence and quality of their work. So far, the lack of autocritic elimination strategy approaches may expose inbred circles that did not properly grasp the fact that antibiotics, trichiasis surgery and education limited to improvement of hygiene are inefficient if not associated with long-term basic educational actions in schools.
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Affiliation(s)
- Pablo Goldschmidt
- Laboratorie du Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts , 28, rue de Charenton, Paris 75012, France
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9
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Buchacher T, Wiesinger-Mayr H, Vierlinger K, Rüger BM, Stanek G, Fischer MB, Weber V. Human blood monocytes support persistence, but not replication of the intracellular pathogen C. pneumoniae. BMC Immunol 2014; 15:60. [PMID: 25488836 PMCID: PMC4268907 DOI: 10.1186/s12865-014-0060-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/01/2014] [Indexed: 01/09/2023] Open
Abstract
Background Intracellular pathogens have devised various mechanisms to subvert the host immune response in order to survive and replicate in host cells. Here, we studied the infection of human blood monocytes with the intracellular pathogen C. pneumoniae and the effect on cytokine and chemokine profiles in comparison to stimulation with LPS. Results Monocytes purified from peripheral blood mononuclear cells by negative depletion were infected with C. pneumoniae. While immunofluorescence confirmed the presence of chlamydial lipopolysaccharide (LPS) in the cytoplasm of infected monocytes, real-time PCR did not provide evidence for replication of the intracellular pathogen. Complementary to PCR, C. pneumoniae infection was confirmed by an oligonucleotide DNA microarray for the detection of intracellular pathogens. Raman microspectroscopy revealed different molecular fingerprints for infected and non-infected monocytes, which were mainly due to changes in lipid and fatty acid content. Stimulation of monocytes with C. pneumoniae or with LPS induced similar profiles of tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6, but higher levels of IL-1β, IL-12p40 and IL-12p70 for C. pneumoniae which were statistically significant. C. pneumoniae also induced release of the chemokines MCP-1, MIP-1α and MIP-1β, and CXCL-8, which correlated with TNF-α secretion. Conclusion Infection of human blood monocytes with intracellular pathogens triggers altered cytokine and chemokine pattern as compared to stimulation with extracellular ligands such as LPS. Complementing conventional methods, an oligonucleotide DNA microarray for the detection of intracellular pathogens as well as Raman microspectroscopy provide useful tools to trace monocyte infection. Electronic supplementary material The online version of this article (doi:10.1186/s12865-014-0060-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tanja Buchacher
- Christian Doppler Laboratory for Innovative Therapy Approaches in Sepsis, Danube University Krems, Krems, Austria.
| | | | | | - Beate M Rüger
- Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria.
| | - Gerold Stanek
- Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria.
| | - Michael B Fischer
- Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria. .,Department for Health Sciences and Biomedicine, Danube University Krems, Krems, Austria.
| | - Viktoria Weber
- Christian Doppler Laboratory for Innovative Therapy Approaches in Sepsis, Danube University Krems, Krems, Austria. .,Department for Health Sciences and Biomedicine, Danube University Krems, Krems, Austria.
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Dean D, Rothschild J, Ruettger A, Kandel RP, Sachse K. Zoonotic Chlamydiaceae species associated with trachoma, Nepal. Emerg Infect Dis 2014; 19:1948-55. [PMID: 24274654 PMCID: PMC3840858 DOI: 10.3201/eid1912.130656] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Trachoma is the leading cause of preventable blindness. Commercial assays do not discriminate among all Chlamydiaceae species that might be involved in trachoma. We investigated whether a commercial Micro-ArrayTube could discriminate Chlamydiaceae species in DNA extracted directly from conjunctival samples from 101 trachoma patients in Nepal. To evaluate organism viability, we extracted RNA, reverse transcribed it, and subjected it to quantitative real-time PCR. We found that 71 (70.3%) villagers were infected. ArrayTube sensitivity was 91.7% and specificity was 100% compared with that of real-time PCR. Concordance between genotypes detected by microarray and ompA genotyping was 100%. Species distribution included 54 (76%) single infections with Chlamydia trachomatis, C. psittaci, C. suis, or C. pecorum, and 17 (24%) mixed infections that includied C. pneumoniae. Ocular infections were caused by 5 Chlamydiaceae species. Additional studies of trachoma pathogenesis involving Chlamydiaceae species other than C. trachomatis and their zoonotic origins are needed.
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Enzymatic treatment of specimens before DNA extraction directly influences molecular detection of infectious agents. PLoS One 2014; 9:e94886. [PMID: 24936792 PMCID: PMC4061000 DOI: 10.1371/journal.pone.0094886] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/20/2014] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Biological samples, pharmaceuticals or food contain proteins, lipids, polymers, ammoniums and macromolecules that alter the detection of infectious agents by DNA amplification techniques (PCR). Moreover the targeted DNA has to be released from the complex cell walls and the compact nucleoprotein matrixes and cleared from potential inhibitors. The goal of the present work was to assess the efficiency of enzymatic pretreatments on infectious agents to make DNA available for further extraction and amplification. METHODS Staphylococcus epidermidis, Streptococcus mitis, Propionibacterium acnes, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger and Fusarium solani were mixed with an internal control virus and treated with: 1) proteinase K; 2) lyticase and 3) lyticase followed by proteinase K. DNAs was manually extracted using the QIAmp DNA Mini kit or the MagNA Pure Compact automate. DNA extraction yields and the inhibitors were assessed with a phocid Herpesvirus. Bacterial detection was performed using TaqMan real-time PCR and yeasts and filamentous Fungi with HRM (real-time PCR followed by high-resolution melting analysis). RESULTS Viral DNA was released, extracted and detected using manual and automatic methods without pre enzymatic treatments. Either the manual or the automatic DNA extraction systems did not meet the sensitivity expectations if enzymatic treatments were not performed before: lyticase for Fungi and Proteinase K for Bacteria. The addition of lyticase and proteinase K did not improve results. For Fungi the detection after lyticase was higher than for Proteinase K, for which melting analysis did not allow fungal specification. DISCUSSION Columns and magnetic beads allowed collecting DNA and separate PCR inhibitors. Detection rates cannot be related to DNA-avidity of beads or to elution but to the lack of proteolysis.
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Goldschmidt P, Einterz E. The limits of medical interventions for the elimination of preventable blindness. Trop Med Health 2014; 42:43-52. [PMID: 24808746 PMCID: PMC3965845 DOI: 10.2149/tmh.2013-26] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/21/2013] [Indexed: 11/11/2022] Open
Abstract
Background: Health authorities are working toward the global elimination of trachoma by the year 2020 with actions focused on the World Health Organization SAFE strategy (surgery of trichiasis, antibiotics, face washing and environmental changes) with emphasis on hygienist approaches for education. Objectives: The present survey was performed to assess the sustainability of the SAFE strategy 3 years after trachoma was eliminated from 6 villages. Methods: In February 2013 a rapid trachoma assessment was conducted in 6 villages of Kolofata’s district, Extreme north Region, Cameroon, where trachoma was eliminated in 2010. A total of 300 children (1–10 years) from 6 villages were examined by trained staff. Results: The prevalence of active trachoma (children aged > 1 and < 10 years) in 2013 was 15% and in at least 25% was observed absence of face washing and flies in their eyes and nose. Income level, quality of roads, hygiene, and illiteracy were similar in all the villages; they did not change between 2010 and 2013 and could not be analyzed as independent risk factors. Discussion: The heterogeneity of methods described for clinical trials makes it inappropriate to conduct meta-analysis for the present and for other SAFE-related trials. The results obtained after implementation the SAFE strategy (recurrence) reveal that the causes (infectious agents and dirtiness) and effects (illness) were not connected by illiterate people living under conditions of extreme poverty. So far, antibiotics, surgery and hygiene education are insufficient for the sustainability of trachoma elimination and highlight that hypothetic-deductive processes seem not operational after implementing the awareness campaigns. Trachoma recurrence detected in 2013 in sedentary populations of Kolofata receiving efficacious treatments against Chlamydia sp. suggest that the elimination goals will be delayed if strategies are limited to medical actions. Restricting efforts to repeated pharmacological and surgical interventions for people infected with susceptible bacteria could be understood as the hidden side of a passive attitude toward basic education actions.
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Affiliation(s)
- Pablo Goldschmidt
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris France and Ophtalmo sans Frontières, Luçon, France
| | - Ellen Einterz
- Hôpital de District de Kolofata, Far North Region, Cameroon
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Wasson CJ, Zourelias JL, Aardsma NA, Eells JT, Ganger MT, Schober JM, Skwor TA. Inhibitory effects of 405 nm irradiation on Chlamydia trachomatis growth and characterization of the ensuing inflammatory response in HeLa cells. BMC Microbiol 2012; 12:176. [PMID: 22894815 PMCID: PMC3438111 DOI: 10.1186/1471-2180-12-176] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 08/13/2012] [Indexed: 11/17/2022] Open
Abstract
Background Chlamydia trachomatis is an intracellular bacterium that resides in the conjunctival and reproductive tract mucosae and is responsible for an array of acute and chronic diseases. A percentage of these infections persist even after use of antibiotics, suggesting the need for alternative treatments. Previous studies have demonstrated anti-bacterial effects using different wavelengths of visible light at varying energy densities, though only against extracellular bacteria. We investigated the effects of visible light (405 and 670 nm) irradiation via light emitting diode (LEDs) on chlamydial growth in endocervical epithelial cells, HeLa, during active and penicillin-induced persistent infections. Furthermore, we analyzed the effect of this photo treatment on the ensuing secretion of IL-6 and CCL2, two pro-inflammatory cytokines that have previously been identified as immunopathologic components associated with trichiasis in vivo. Results C. trachomatis-infected HeLa cells were treated with 405 or 670 nm irradiation at varying energy densities (0 – 20 J/cm2). Bacterial growth was assessed by quantitative real-time PCR analyzing the 16S: GAPDH ratio, while cell-free supernatants were examined for IL-6 and monocyte chemoattractant protein-1 (CCL2) production. Our results demonstrated a significant dose-dependent inhibitory effect on chlamydial growth during both active and persistent infections following 405 nm irradiation. Diminished bacterial load corresponded to lower IL-6 concentrations, but was not related to CCL2 levels. In vitro modeling of a persistent C. trachomatis infection induced by penicillin demonstrated significantly elevated IL-6 levels compared to C. trachomatis infection alone, though 405 nm irradiation had a minimal effect on this production. Conclusion Together these results identify novel inhibitory effects of 405 nm violet light on the bacterial growth of intracellular bacterium C. trachomatis in vitro, which also coincides with diminished levels of the pro-inflammatory cytokine IL-6.
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Goldschmidt P, Benallaoua D, Amza A, Einterz E, Huguet P, Poisson F, Bilinkai AB, Ismaila M, Bensaid P, Bella L, Chaumeil C. Clinical and microbiological assessment of trachoma in the kolofata health district, far north region, cameroon. Trop Med Health 2012; 40:7-14. [PMID: 22949801 PMCID: PMC3426829 DOI: 10.2149/tmh.2011-26] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 12/01/2011] [Indexed: 12/04/2022] Open
Abstract
Background and aims: Trachoma is a sight-threatening process triggered by the infection of the conjunctiva with Chlamydiae. Blindness associated with trachoma was reported in Sahelian areas of Cameroon. However, data on the prevalence of this neglected infection in the Far North Region are not available. The aim of this study was a) to assess clinical trachoma and b) to detect Chlamydia in the conjunctiva of trachomatous populations living in the Far North Regions of Cameroon. Methods: A total of 2,423 randomly selected children (1–10 years) and 1,590 women over 14 from randomly selected villages from the Kolofata Health District (115,000 inhabitants) were included in a cross-sectional study in February 2009. Trained staff examined and obtained conjunctival swabs from trachomatous subjects. DNA was extracted and amplified to detect Chlamydia DNA by real-time PCR. The quality of sampling was assessed by quantifying the number of epithelial cells. Results: Children (2,397 or 98.9% of the predicted number) and women (1,543; 97.0%) were examined. The prevalence of follicular trachoma (TF) in children was 21% (95% CI 17.8–24.5) and of intense inflammatory trachoma (TI) 5.2% (95% CI 3.6–7.3). Among the women, trichiasis (TT) was observed in 3.4% (95% CI 2.4–4.7), corneal opacities (CO) in 1.4% (95% CI 0.8–2.3) and trachoma-related blindness in 0.9% (95% CI 0.4–1.8). Conditions related to income, illiteracy, latrines, water supply and animals wandering close to dwellings were similar in all the villages. PCR was positive in 35% of children with active trachoma and in 6% of adult females presenting TT and/or related corneal opacities. Conclusion: The prevalence of trachoma and the severe trachoma sequelae found during this survey underline the urgent need to implement efficient blindness prevention interventions to improve the visual future of the people in the Sahelian region.
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Affiliation(s)
- Pablo Goldschmidt
- Laboratoire du Centre National d'Ophtalmologie des Quinze-Vingts, Paris, France
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Sibley CD, Peirano G, Church DL. Molecular methods for pathogen and microbial community detection and characterization: current and potential application in diagnostic microbiology. INFECTION GENETICS AND EVOLUTION 2012; 12:505-21. [PMID: 22342514 PMCID: PMC7106020 DOI: 10.1016/j.meegid.2012.01.011] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/25/2022]
Abstract
Clinical microbiology laboratories worldwide have historically relied on phenotypic methods (i.e., culture and biochemical tests) for detection, identification and characterization of virulence traits (e.g., antibiotic resistance genes, toxins) of human pathogens. However, limitations to implementation of molecular methods for human infectious diseases testing are being rapidly overcome allowing for the clinical evaluation and implementation of diverse technologies with expanding diagnostic capabilities. The advantages and limitation of molecular techniques including real-time polymerase chain reaction, partial or whole genome sequencing, molecular typing, microarrays, broad-range PCR and multiplexing will be discussed. Finally, terminal restriction fragment length polymorphism (T-RFLP) and deep sequencing are introduced as technologies at the clinical interface with the potential to dramatically enhance our ability to diagnose infectious diseases and better define the epidemiology and microbial ecology of a wide range of complex infections.
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Affiliation(s)
- Christopher D. Sibley
- Department of Microbiology, Immunology & Infectious Diseases, Faculty of Medicine, University of Calgary, Calgary, Alta, Canada
| | - Gisele Peirano
- Division of Microbiology, Calgary Laboratory Services, Calgary, Alta, Canada
| | - Deirdre L. Church
- Department of Pathology & Laboratory Medicine, Faculty of Medicine, University of Calgary, Calgary, Alta, Canada
- Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, Alta, Canada
- Division of Microbiology, Calgary Laboratory Services, Calgary, Alta, Canada
- Corresponding author. Address: c/o Calgary Laboratory Services, 9-3535 Research Rd. N.W., Calgary, Alta, Canada T2L 2K8. Tel.: +1 403 770 3281; fax: +1 403 770 3347.
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See CW, Alemayehu W, Melese M, Zhou Z, Porco TC, Shiboski S, Gaynor BD, Eng J, Keenan JD, Lietman TM. How reliable are tests for trachoma?--a latent class approach. Invest Ophthalmol Vis Sci 2011; 52:6133-7. [PMID: 21685340 DOI: 10.1167/iovs.11-7419] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
PURPOSE Tests for ocular Chlamydia trachomatis have not been well characterized, because there is no gold standard test. Latent class analysis (LCA) was performed to estimate the sensitivity and specificity of laboratory and clinical tests for trachoma in the absence of a gold standard. METHODS Individual data from pretreatment, hyperendemic areas in Ethiopia were used. A clustered LCA was performed for three diagnostic tests: PCR and WHO simplified criteria grades of follicular trachoma (TF) and intense trachomatous inflammation (TI). RESULTS Data from 2111 subjects in 40 villages were available. TF was estimated to be 87.3% (95% CI, 83.3-90.1) sensitive and 36.6% (95% CI, 23.6-40.3) specific; TI was estimated to be 53.6% (95% CI, 46.1-88.0) sensitive and 88.3% (95% CI, 83.3-92.0) specific, and PCR was estimated to be 87.5% (95% CI, 79.9-97.2) sensitive and 100% (95% CI 69.3-100) specific. CONCLUSIONS LCA allows for an estimate of test characteristics without prior assumption of their performance. TF and TI were found to act in a complementary manner: TF is a sensitive test and TI is a specific test. PCR is highly specific but lacks sensitivity. The performance of these tests may be due to the time course of ocular chlamydial infection, and for this reason, results may differ in areas of low prevalence or recent mass treatment (ClinicalTrials.gov number, NCT00221364).
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Affiliation(s)
- Craig W See
- F I Proctor Foundation, University of California San Francisco, San Francisco, California 94143-0412, USA
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Harding-Esch EM, Holland MJ, Schémann JF, Molina S, Sarr I, Andreasen AA, Roberts CH, Sillah A, Sarr B, Harding EF, Edwards T, Bailey RL, Mabey DCW. Diagnostic accuracy of a prototype point-of-care test for ocular Chlamydia trachomatis under field conditions in The Gambia and Senegal. PLoS Negl Trop Dis 2011; 5:e1234. [PMID: 21829735 PMCID: PMC3149007 DOI: 10.1371/journal.pntd.0001234] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 05/22/2011] [Indexed: 11/21/2022] Open
Abstract
Background The clinical signs of active trachoma are often present in the absence of ocular Chlamydia trachomatis infection in low prevalence and mass treated settings. Treatment decisions are currently based on the prevalence of clinical signs, and this may result in the unnecessary distribution of mass antibiotic treatment. We aimed to evaluate the diagnostic accuracy of a prototype point-of-care (POC) test, developed for field diagnosis of ocular C. trachomatis, in low prevalence settings of The Gambia and Senegal. Methodology/Principal Findings Three studies were conducted, two in The Gambia and one in Senegal. Children under the age of 10 years were screened for the clinical signs of trachoma. Two ocular swabs were taken from the right eye. The first swab was tested by the POC test in the field and the result independently graded by two readers. The second swab was tested for the presence of C. trachomatis by Amplicor Polymerase Chain Reaction. In Senegal, measurements of humidity and temperature in the field were taken. A total of 3734 children were screened, 950 in the first and 1171 in the second Gambian study, and 1613 in Senegal. The sensitivity of the prototype POC test ranged between 33.3–67.9%, the specificity between 92.4–99.0%, the positive predictive value between 4.3–21.0%, and the negative predictive value between 98.0–99.8%. The rate of false-positives increased markedly at temperatures above 31.4°C and relative humidities below 11.4%. Conclusions/Significance In its present format, this prototype POC test is not suitable for field diagnosis of ocular C. trachomatis as its specificity decreases in hot and dry conditions: the environment in which trachoma is predominantly found. In the absence of a suitable test for infection, trachoma diagnosis remains dependent on clinical signs. Under current WHO recommendations, this is likely resulting in the continued mass treatment of non-infected communities. Trachoma, caused by infection of the eye with the bacterium Chlamydia trachomatis, is the leading infectious cause of blindness and is associated with poverty. Antibiotic treatment of all community members is one of the recommended control strategies for trachoma. However, in places where the prevalence of clinical signs is low, C. trachomatis eye infection is often absent. Laboratory testing for C. trachomatis infection by polymerase chain reaction (PCR) is highly sensitive but expensive and requires well-trained staff. A simple point-of-care (POC) test that can be used in trachoma-affected communities could help trachoma control efforts. We evaluated a POC test for C. trachomatis eye infection. Children under 10 years of age were screened for clinical signs of trachoma and C. trachomatis eye infection. The POC test result was compared with laboratory PCR test results. The POC test detected just over half of PCR test positives correctly. However, the POC test tended to give false-positive results in hot and dry conditions, which is the typical environment of trachoma. The POC test requires high specificity since it would be used to make treatment decisions at the community level. Therefore, its present format requires improvement before it can be utilized in trachoma control.
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Affiliation(s)
| | - Martin J. Holland
- London School of Hygiene and Tropical Medicine, London, United Kingdom
- Medical Research Council Laboratories, Fajara, Banjul, The Gambia
| | | | - Sandra Molina
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Isatou Sarr
- Medical Research Council Laboratories, Fajara, Banjul, The Gambia
| | - Aura A. Andreasen
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Ansumana Sillah
- National Eye Care Programme, Ministry of Health, Banjul, The Gambia
| | - Boubacar Sarr
- Programme National de Lutte contre la Cécité, Ministère de la Santé, Dakar, Sénégal
| | | | - Tansy Edwards
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Robin L. Bailey
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - David C. W. Mabey
- London School of Hygiene and Tropical Medicine, London, United Kingdom
- * E-mail:
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18
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Errera MH, Goldschmidt P, Batellier L, Degorge S, Héron E, Laroche L, Sahel JA, Westcott M, Chaumeil C. Real-time polymerase chain reaction and intraocular antibody production for the diagnosis of viral versus toxoplasmic infectious posterior uveitis. Graefes Arch Clin Exp Ophthalmol 2011; 249:1837-46. [PMID: 21732111 DOI: 10.1007/s00417-011-1724-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Revised: 04/21/2011] [Accepted: 05/21/2011] [Indexed: 10/18/2022] Open
Abstract
PURPOSE The aim of this work was to determine the diagnostic performance of real-time polymerase chain reaction (RT-PCR) and to assess intraocular specific antibody secretion (Goldmann-Witmer coefficient) on samples from patients with signs of posterior uveitis presumably of infectious origin and to target the use of these two biologic tests in the diagnostic of Toxoplasma/viral Herpesviridae posterior uveitis by the consideration of clinical behavior and delay of intraocular sampling. METHODS Aqueous humour and/or vitreous fluid were collected from patients suspected of having posterior uveitis of infectious origin at presentation (140 samples). The diagnosis was confirmed by quantification of antibodies with the Goldmann-Witmer coefficient (GWC) and for detection of Herpesviridae and Toxoplasma gondii genomes with RT-PCR. Forty-one patients had final diagnosis of uveitis of non-Toxoplasma/non-viral origin and 35 among them constituted the control group. The main outcome measures were sensitivity, specificity, and positive and negative predictive values (PPV and NPV). RESULTS When pre-intraocular testing indication was compared with final diagnosis, GWC was a more sensitive and specific method than RT-PCR, and was successful in detecting T. gondii, especially if the patient is immunocompetent and the testing is carried out later in the disease course, up to 15 months. For viral Herpesviridae uveitis, the sensitivity and PPV of PCR evaluation was higher than detected with GWC with respectively 46% compared with 20% for sensitivity and 85% versus 60% for PPV. In either viral retinitis or toxoplasmosis infection, RT-PCR results were positive from 24 h, although GWC was not significant until 1 week after the onset of signs. In toxoplasmosis patients, positive RT-PCR results were statistically correlated with the chorioretinitis area (more than three disc areas; p = 0.002), with the age older than 50 (p = 0.0034) and with a clinical anterior inflammation (Tyndall ≥1/2+) and panuveitis; (p = 0.0001). CONCLUSIONS For the diagnosis of viral or toxoplasmosis-associated intraocular inflammation, the usefulness of laboratory diagnosis tools (RT-PCR and GWC) depends on parameters other than the sensitivity of the tests. Certain patient characteristics such as the age of the patients, immune status, duration since the onset of symptoms, retinitis area, predominant site and extent of inflammation within the eye should orientate the rational for the choice of laboratory testing in analysis of intraocular fluids.
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Affiliation(s)
- Marie-Hélène Errera
- Service d'Ophtalmologie IV, Centre National d'Ophtalmologie des Quinze-Vingts, 28 rue de Charenton, 75012, Paris, France.
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Fraeyman A, Boel A, Van Vaerenbergh K, De Beenhouwer H. Atypical pneumonia due to Chlamydophila psittaci: 3 case reports and review of literature. Acta Clin Belg 2010; 65:192-6. [PMID: 20669788 DOI: 10.1179/acb.2010.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Chlamydophila psittaci is the causative agent of psittacosis or ornithosis. The disease is transmitted to men predominantly from birds. Most commonly noted symptoms are fever, headache and cough, but a number of other symptoms or complications may arise such as renal impairment, hepatitis or neurological symptoms. In this article 3 cases of psittacosis are presented, with a review of the literature with emphasis on laboratory diagnosis.
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Affiliation(s)
- A Fraeyman
- Klinisch Laboratorium afdeling microbiologie, OLV Ziekenhuis, Aalst, Belgium.
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Wooters MA, Kaufhold RM, Field JA, Indrawati L, Heinrichs JH, Smith JG. A real-time quantitative polymerase chain reaction assay for the detection of Chlamydia in the mouse genital tract model. Diagn Microbiol Infect Dis 2008; 63:140-7. [PMID: 19026505 DOI: 10.1016/j.diagmicrobio.2008.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 10/11/2008] [Indexed: 11/18/2022]
Abstract
Chlamydia trachomatis is a human pathogen that infects genital tracts in women. Disease control may be achieved through development of an efficacious vaccine. A mouse genital tract model serves as a tool for evaluation of vaccine candidates. Currently, assessment of infection in mice is performed by enumeration of inclusion-forming units (IFUs) through microscopic counting of fluorescently stained bacteria. We have developed a highly sensitive real-time quantitative polymerase chain reaction (RT-qPCR) assay for enumeration of Chlamydia from mouse genital tracts to increase assay sensitivity, remove subjectivity, and improve sample throughput. The qPCR assay uses a 16S ribosomal gene sequence that is conserved across Chlamydia species and serovars, resulting in detection of multiple serovars of C. trachomatis, as well as Chlamydia muridarum and Chlamydia pneumoniae. The PCR assay provided results similar to IFU enumeration (94% agreement between the 2 assays) and is highly sensitive and specific with less inherent subjectivity than traditional enumeration methods.
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Affiliation(s)
- Melissa A Wooters
- Vaccine Basic Research, Merck Research Laboratories, West Point, PA 19486-0004, USA.
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Dean D, Kandel RP, Adhikari HK, Hessel T. Multiple Chlamydiaceae species in trachoma: implications for disease pathogenesis and control. PLoS Med 2008; 5:e14. [PMID: 18177205 PMCID: PMC2174965 DOI: 10.1371/journal.pmed.0050014] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Accepted: 11/09/2007] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Chlamydia trachomatis is a unique obligate intracellular bacterium that remains the leading cause of sexually transmitted bacterial diseases and preventable blindness worldwide. Chronic ocular infections are referred to as trachoma, and predominate in developing countries. Since 2001, the World Health Organization has promoted control strategies including antibiotics, improved hygiene, and environmental measures with limited success. Consequently, a vaccine is urgently needed. Integral to vaccine design is an understanding of the interactions of the pathogen and host immune response. Various animal models of trachoma show that urogenital C. trachomatis strains and other species of the family Chlamydiaceae produce severe conjunctival inflammation and scarring similar to that of the ocular C. trachomatis strains. However, we do not know the extent of organisms that may be involved in human trachoma. Furthermore, C. trachomatis heat shock protein 60 (Hsp60) has been implicated in inflammation and conjunctival scarring but the role of other Chlamydiaceae Hsp60 in disease pathogenesis has not been examined. In this study, we set out to identify whether other Chlamydiaceae species are present in trachoma, and determine their association with severity of clinical disease and with mucosal and systemic immune responses to Chlamydiaceae species-specific Hsp60 to further investigate the immunopathogenesis of this blinding disease. METHODS AND FINDINGS We randomly selected nine of 49 households in a trachoma-endemic region of Nepal. Trachoma was graded, and real-time, quantitative (k)PCR was used to detect genomic DNA and cDNA (from RNA) for Chlamydiaceae ompA and 16S rRNA genes, respectively, from conjunctival swabs. IgG antibody responses to recombinant (r) Chlamydiaceae species-specific Hsp60 were determined for tears and sera. Surprisingly, all three species-C. trachomatis, Chlamydophila psittaci, and Chlamydophila pneumoniae-were detected in eight (89%) study households; one household had no members infected with C. pneumoniae. Of 80 (63%; n = 127) infected individuals, 28 (35%) had infection with C. psittaci, or C. pneumoniae, or both; single and dual infections with C. psittaci and C. pneumoniae were significantly associated with severe conjunctival inflammation (OR 4.25 [95% confidence interval (CI), 2.9-11.3], p = 0.009] as were single infections with C. trachomatis (OR 5.7 [95% CI, 3.8-10.1], p = 0.002). Of the 80 infected individuals, 75 (93.8%) were also positive for 16S rRNA by kPCR for the same organism identified by ompA. Individuals with tear IgG immunoreactivity to Chlamydiaceae rHsp60 were eight times more likely than individuals without tear immunoreactivity to be infected (95% CI 6.4-15.1; p = 0.003), 6.2 times more likely to have severe inflammation (95% CI 4.4-12.6; p = 0.001), and 5.7 times more likely to have scarring (95% CI 3.9-11.1; p = 0.019) while individuals with serum IgG immunoreactivity were 4.1 times more likely to be infected (95% CI 3.1-10.1; p = 0.014). CONCLUSIONS We provide substantial evidence for the involvement of C. psittaci and C. pneumoniae, in addition to C. trachomatis, in trachoma. The distribution of Chlamydiaceae species by household and age suggests that these infections are widespread and not just sporadic occurrences. Infection with multiple species may explain the failure to detect chlamydiae among active trachoma cases, when only C. trachomatis is assayed for, and the failure of clinically active cases to resolve their disease following what would be considered effective C. trachomatis treatment. The evidence for viable (RNA-positive) organisms of all three species in single and coinfections, the significant association of these infections with severe inflammation, and the significant association of tear and serum IgG responses to Chlamydiaceae Hsp60 with inflammation and scarring, support the role of all three species in disease pathogenesis. Thus, while our findings should be confirmed in other trachoma-endemic countries, our data suggest that a reevaluation of treatment regimens and vaccine design may be required. Understanding the full impact of Chlamydiaceae species on the epidemiology, immunopathology, and disease outcome of trachoma presents a new challenge for Chlamydiaceae research.
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Affiliation(s)
- Deborah Dean
- Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California, United States of America.
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