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Atluri VL, Stalter RM, McGuffin SA, Johnson L, Healy B, Benesch HA, Lan K, Marsland P, Pottinger P, Patel RC. Patient characteristics associated with conversion from negative to positive severe acute respiratory syndrome coronavirus-2 polymerase chain reaction test results: Implications for clinical false-negativity from a single-center: A case-control study. J Med Virol 2022; 94:4792-4802. [PMID: 35698816 PMCID: PMC9350093 DOI: 10.1002/jmv.27932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 06/04/2022] [Accepted: 06/06/2022] [Indexed: 12/02/2022]
Abstract
BACKGROUND Accurate diagnosis of coronavirus disease 2019 is essential to limiting transmission within healthcare settings. The aim of this study was to identify patient demographic and clinical characteristics that could impact the clinical sensitivity of the nasopharyngeal severe acute respiratory syndrome coronavirus-2 (SARS-CoV2) reverse transcription polymerase chain reaction (RT-PCR) test. METHODS We conducted a retrospective, matched case-control study of patients who underwent repeated nasopharyngeal SARS-CoV2 RT-PCR testing at a tertiary care academic medical center between March 1 and July 23, 2020. The primary endpoint was conversion from negative to positive PCR status within 14 days. We conducted conditional logistic regression modeling to assess the associations between demographic and clinical features and conversion to test positivity. RESULTS Of 51,116 patients with conclusive SARS-CoV2 nasopharyngeal RT-PCR results, 97 patients converted from negative to positive within 14 days. We matched those patients 1:2 to 194 controls by initial test date. In multivariate analysis, clinical suspicion for a respiratory infection (adjusted odds ratio [aOR] 20.9, 95% confidence interval [CI]: 3.1-141.2) and lack of pulmonary imaging (aOR 4.7, 95% CI: 1.03-21.8) were associated with conversion, while a lower burden of comorbidities trended toward an increased odds of conversion (aOR 2.2, 95% CI: 0.9-5.3). CONCLUSIONS Symptoms consistent with a respiratory infection, especially in relatively healthy individuals, should raise concerns about a clinical false-negative result. We have identified several characteristics that should be considered when creating institutional infection prevention guidelines in the absence of more definitive data and should be included in future studies.
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Affiliation(s)
- Vidya L. Atluri
- Department of MedicineUniversity of WashingtonSeattleWashingtonUSA
- Department of MedicineVeterans Affairs Central California Healthcare SystemFresnoCaliforniaUSA
| | - Randy M. Stalter
- Department of EpidemiologyUniversity of WashingtonSeattleWashingtonUSA
| | | | - Luke Johnson
- School of MedicineUniversity of WashingtonSeattleWashingtonUSA
| | - Bailey Healy
- School of MedicineUniversity of WashingtonSeattleWashingtonUSA
| | | | - Kristine Lan
- Department of MedicineUniversity of WashingtonSeattleWashingtonUSA
| | - Paula Marsland
- School of MedicineUniversity of WashingtonSeattleWashingtonUSA
| | - Paul Pottinger
- Department of MedicineUniversity of WashingtonSeattleWashingtonUSA
| | - Rena C. Patel
- Departments of Medicine and Global HealthUniversity of WashingtonSeattleWashingtonUSA
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Cooper JJ, Atluri VL, Jain R, Pottinger PS, Coleman DT. Safety of cefazolin for perioperative prophylaxis in patients with penicillin allergy labels. Ann Allergy Asthma Immunol 2022; 129:115-117. [PMID: 35342019 DOI: 10.1016/j.anai.2022.03.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/11/2022] [Accepted: 03/11/2022] [Indexed: 11/25/2022]
Affiliation(s)
- Jocelyn J Cooper
- Division of Internal Medicine, Department of Medicine, University of Washington, Seattle, Washington.
| | - Vidya L Atluri
- Department of Medicine, Veterans Affairs Central California, Fresno, California; Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington
| | - Rupali Jain
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington; School of Pharmacy, University of Washington, Seattle, Washington
| | - Paul S Pottinger
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington
| | - David T Coleman
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington; Division of Allergy and Clinical Immunology, Department of Medicine, Henry Ford Health System, Detroit, Michigan
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Benesch HA, Atluri VL, Healy B, Rampur L. Outcome of trimethoprim-sulfamethoxazole challenge in previously reported patients with sulfa antibiotic allergy. Ann Allergy Asthma Immunol 2021; 127:140-142. [PMID: 33838337 PMCID: PMC8627674 DOI: 10.1016/j.anai.2021.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 03/19/2021] [Accepted: 04/01/2021] [Indexed: 12/20/2022]
Affiliation(s)
- Hailey A Benesch
- School of Medicine, University of Washington, Seattle, Washington
| | - Vidya L Atluri
- Division of Allergy and Infectious Disease, Department of Medicine, University of Washington, Seattle, Washington.
| | - Bailey Healy
- School of Medicine, University of Washington, Seattle, Washington
| | - Lahari Rampur
- Division of Allergy and Infectious Disease, Department of Medicine, University of Washington, Seattle, Washington; Kaiser Permanente Washington, Seattle, Washington
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Byndloss MX, Tsai AY, Walker GT, Miller CN, Young BM, English BC, Seyffert N, Kerrinnes T, de Jong MF, Atluri VL, Winter MG, Celli J, Tsolis RM. Brucella abortus Infection of Placental Trophoblasts Triggers Endoplasmic Reticulum Stress-Mediated Cell Death and Fetal Loss via Type IV Secretion System-Dependent Activation of CHOP. mBio 2019; 10:e01538-19. [PMID: 31337727 PMCID: PMC6650558 DOI: 10.1128/mbio.01538-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 06/24/2019] [Indexed: 01/23/2023] Open
Abstract
Subversion of endoplasmic reticulum (ER) function is a feature shared by multiple intracellular bacteria and viruses, and in many cases this disruption of cellular function activates pathways of the unfolded protein response (UPR). In the case of infection with Brucella abortus, the etiologic agent of brucellosis, the unfolded protein response in the infected placenta contributes to placentitis and abortion, leading to pathogen transmission. Here we show that B. abortus infection of pregnant mice led to death of infected placental trophoblasts in a manner that depended on the VirB type IV secretion system (T4SS) and its effector VceC. The trophoblast death program required the ER stress-induced transcription factor CHOP. While NOD1/NOD2 expression in macrophages contributed to ER stress-induced inflammation, these receptors did not play a role in trophoblast death. Both placentitis and abortion were independent of apoptosis-associated Speck-like protein containing a caspase activation and recruitment domain (ASC). These studies show that B. abortus uses its T4SS to induce cell-type-specific responses to ER stress in trophoblasts that trigger placental inflammation and abortion. Our results suggest further that in B. abortus the T4SS and its effectors are under selection as bacterial transmission factors.IMPORTANCEBrucella abortus infects the placenta of pregnant cows, where it replicates to high levels and triggers abortion of the calf. The aborted material is highly infectious and transmits infection to both cows and humans, but very little is known about how B. abortus causes abortion. By studying this infection in pregnant mice, we discovered that B. abortus kills trophoblasts, which are important cells for maintaining pregnancy. This killing required an injected bacterial protein (VceC) that triggered an endoplasmic reticulum (ER) stress response in the trophoblast. By inhibiting ER stress or infecting mice that lack CHOP, a protein induced by ER stress, we could prevent death of trophoblasts, reduce inflammation, and increase the viability of the pups. Our results suggest that B. abortus injects VceC into placental trophoblasts to promote its transmission by abortion.
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Affiliation(s)
- Mariana X Byndloss
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - April Y Tsai
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Gregory T Walker
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Cheryl N Miller
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Briana M Young
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Bevin C English
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Núbia Seyffert
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Tobias Kerrinnes
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Maarten F de Jong
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Vidya L Atluri
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Maria G Winter
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Jean Celli
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
| | - Renée M Tsolis
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, USA
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5
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Patra KP, Saito M, Atluri VL, Rolán HG, Young B, Kerrinnes T, Smits H, Ricaldi JN, Gotuzzo E, Gilman RH, Tsolis RM, Vinetz JM. A protein-conjugate approach to develop a monoclonal antibody-based antigen detection test for the diagnosis of human brucellosis. PLoS Negl Trop Dis 2014; 8:e2926. [PMID: 24901521 PMCID: PMC4046965 DOI: 10.1371/journal.pntd.0002926] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 04/20/2014] [Indexed: 11/19/2022] Open
Abstract
Human brucellosis is most commonly diagnosed by serology based on agglutination of fixed Brucella abortus as antigen. Nucleic acid amplification techniques have not proven capable of reproducibly and sensitively demonstrating the presence of Brucella DNA in clinical specimens. We sought to optimize a monoclonal antibody-based assay to detect Brucella melitensis lipopolysaccharide in blood by conjugating B. melitensis LPS to keyhole limpet hemocyanin, an immunogenic protein carrier to maximize IgG affinity of monoclonal antibodies. A panel of specific of monoclonal antibodies was obtained that recognized both B. melitensis and B. abortus lipopolysaccharide epitopes. An antigen capture assay was developed that detected B. melitensis in the blood of experimentally infected mice and, in a pilot study, in naturally infected Peruvian subjects. As a proof of principle, a majority (7/10) of the patients with positive blood cultures had B. melitensis lipopolysaccharide detected in the initial blood specimen obtained. One of 10 patients with relapsed brucellosis and negative blood culture had a positive serum antigen test. No seronegative/blood culture negative patients had a positive serum antigen test. Analysis of the pair of monoclonal antibodies (2D1, 2E8) used in the capture ELISA for potential cross-reactivity in the detection of lipopolysaccharides of E. coli O157:H7 and Yersinia enterocolitica O9 showed specificity for Brucella lipopolysaccharide. This new approach to develop antigen-detection monoclonal antibodies against a T cell-independent polysaccharide antigen based on immunogenic protein conjugation may lead to the production of improved rapid point-of-care-deployable assays for the diagnosis of brucellosis and other infectious diseases.
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Affiliation(s)
- Kailash P. Patra
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Mayuko Saito
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Vidya L. Atluri
- Department of Medical Microbiology, University of California Davis, Davis, California, United States of America
| | - Hortensia G. Rolán
- Department of Medical Microbiology, University of California Davis, Davis, California, United States of America
| | - Briana Young
- Department of Medical Microbiology, University of California Davis, Davis, California, United States of America
| | - Tobias Kerrinnes
- Department of Medical Microbiology, University of California Davis, Davis, California, United States of America
| | - Henk Smits
- Department of Biomedical Research, Royal Tropical Institute, Amsterdam, the Netherlands
| | - Jessica N. Ricaldi
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Eduardo Gotuzzo
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Robert H. Gilman
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Laboratory of Research and Development, and Department of Cellular and Molecular Sciences, Faculty of Sciences, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Renee M. Tsolis
- Department of Medical Microbiology, University of California Davis, Davis, California, United States of America
- * E-mail: (RMT); (JMV)
| | - Joseph M. Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, United States of America
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratory of Research and Development, and Department of Cellular and Molecular Sciences, Faculty of Sciences, Universidad Peruana Cayetano Heredia, Lima, Peru
- * E-mail: (RMT); (JMV)
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Xavier MN, Winter MG, Spees AM, den Hartigh AB, Nguyen K, Roux CM, Silva TMA, Atluri VL, Kerrinnes T, Keestra AM, Monack DM, Luciw PA, Eigenheer RA, Bäumler AJ, Santos RL, Tsolis RM. PPARγ-mediated increase in glucose availability sustains chronic Brucella abortus infection in alternatively activated macrophages. Cell Host Microbe 2013; 14:159-70. [PMID: 23954155 PMCID: PMC3777723 DOI: 10.1016/j.chom.2013.07.009] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 05/17/2013] [Accepted: 06/20/2013] [Indexed: 01/16/2023]
Abstract
Eradication of persistent intracellular bacterial pathogens with antibiotic therapy is often slow or incomplete. However, strategies to augment antibiotics are hampered by our poor understanding of the nutritional environment that sustains chronic infection. Here we show that the intracellular pathogen Brucella abortus survives and replicates preferentially in alternatively activated macrophages (AAMs), which are more abundant during chronic infection. A metabolic shift induced by peroxisome proliferator-activated receptor γ (PPARγ), which increases intracellular glucose availability, is identified as a causal mechanism promoting enhanced bacterial survival in AAMs. Glucose uptake was crucial for increased replication of B. abortus in AAMs, and for chronic infection, as inactivation of the bacterial glucose transporter gluP reduced both intracellular survival in AAMs and persistence in mice. Thus, a shift in intracellular nutrient availability induced by PPARγ promotes chronic persistence of B. abortus within AAMs, and targeting this pathway may aid in eradicating chronic infection.
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Affiliation(s)
- Mariana N. Xavier
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
- Departamento de Clinica e Cirurgia Veterinarias, Escola de Veterinaria, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
| | - Maria G. Winter
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Alanna M. Spees
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Andreas B. den Hartigh
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Kim Nguyen
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Christelle M. Roux
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Teane M. A. Silva
- Departamento de Clinica e Cirurgia Veterinarias, Escola de Veterinaria, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
| | - Vidya L. Atluri
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Tobias Kerrinnes
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - A. Marijke Keestra
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Denise M. Monack
- Department of Microbiology & Immunology, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA
| | - Paul A. Luciw
- Center for Comparative Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Richard A. Eigenheer
- Proteomics Core Facility, University of California at Davis Genome Center, Davis, CA, 95616, USA
| | - Andreas J. Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Renato L. Santos
- Departamento de Clinica e Cirurgia Veterinarias, Escola de Veterinaria, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
| | - Renée M. Tsolis
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA, 95616, USA
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Xavier MN, Winter MG, Spees AM, Nguyen K, Atluri VL, Silva TMA, Bäumler AJ, Müller W, Santos RL, Tsolis RM. CD4+ T cell-derived IL-10 promotes Brucella abortus persistence via modulation of macrophage function. PLoS Pathog 2013; 9:e1003454. [PMID: 23818855 PMCID: PMC3688575 DOI: 10.1371/journal.ppat.1003454] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 05/08/2013] [Indexed: 12/21/2022] Open
Abstract
Evasion of host immune responses is a prerequisite for chronic bacterial diseases; however, the underlying mechanisms are not fully understood. Here, we show that the persistent intracellular pathogen Brucella abortus prevents immune activation of macrophages by inducing CD4(+)CD25(+) T cells to produce the anti-inflammatory cytokine interleukin-10 (IL-10) early during infection. IL-10 receptor (IL-10R) blockage in macrophages resulted in significantly higher NF-kB activation as well as decreased bacterial intracellular survival associated with an inability of B. abortus to escape the late endosome compartment in vitro. Moreover, either a lack of IL-10 production by T cells or a lack of macrophage responsiveness to this cytokine resulted in an increased ability of mice to control B. abortus infection, while inducing elevated production of pro-inflammatory cytokines, which led to severe pathology in liver and spleen of infected mice. Collectively, our results suggest that early IL-10 production by CD25(+)CD4(+) T cells modulates macrophage function and contributes to an initial balance between pro-inflammatory and anti-inflammatory cytokines that is beneficial to the pathogen, thereby promoting enhanced bacterial survival and persistent infection.
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Affiliation(s)
- Mariana N. Xavier
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
- Departamento de Clínica e Cirurgia Veterinárias, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Maria G. Winter
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
| | - Alanna M. Spees
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
| | - Kim Nguyen
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
| | - Vidya L. Atluri
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
| | - Teane M. A. Silva
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
- Departamento de Clínica e Cirurgia Veterinárias, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Andreas J. Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
| | - Werner Müller
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Renato L. Santos
- Departamento de Clínica e Cirurgia Veterinárias, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Renée M. Tsolis
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California, United States of America
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Abstract
Brucellosis is a zoonotic infection caused primarily by the bacterial pathogens Brucella melitensis and B. abortus. It is acquired by consumption of unpasteurized dairy products or by contact with infected animals. Globally, it is one of the most widespread zoonoses, with 500,000 new cases reported each year. In endemic areas, Brucella infections represent a serious public health problem that results in significant morbidity and economic losses. An important feature of the disease is persistent bacterial colonization of the reticuloendothelial system. In this review we discuss recent insights into mechanisms of intracellular survival and immune evasion that contribute to systemic persistence by the pathogenic Brucella species.
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Affiliation(s)
- Vidya L Atluri
- Medical Microbiology and Immunology, School of Medicine, University of California, Davis, California 95616, USA.
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Portaluppi F, Vadlamudi LS, Atluri VL, Knighten V, Luisada AA. The pulmonary component of the second heart sound in acquired aortic stenosis. Jpn Heart J 1981; 22:527-36. [PMID: 7300024 DOI: 10.1536/ihj.22.527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The amplitude of the pulmonic component of the second sound in aortic stenosis was studied in 49 patients with this lesion. As controls, 50 normal subjects were also studied. Both groups were investigated by phonocardiography, apex cardiography and arterial tracings. Nineteen patients with aortic stenosis and four subjects without it were also studied by cardiac catheterization and angiography. The amplitudes of the two components of the second sound were compared, and the ratio of each with the amplitude of the first sound was determined. The ratios of both the aortic and the pulmonic component to that of the first sound were decreased in aortic stenosis, and the decrease of the pulmonic component was comparable to that of the aortic component. These findings could be related to prolongation of the isovolumic relaxation period of both ventricles caused by an influence of the left ventricle on the right, most likely due to functional changes of the interventricular septum.
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