L02 Chapter 21 - Spirochete Diseases PDF

6/27/2024 Spirochete Diseases Chapter 21 Preamble PowerPoints are a general overview and are provided to help students take notes over the video lecture ONLY. PowerPoints DO NOT cover the details needed for the Unit exam Each student is responsible for READING the TEXTBOOK for de...

6/27/2024 Spirochete Diseases Chapter 21 Preamble PowerPoints are a general overview and are provided to help students take notes over the video lecture ONLY. PowerPoints DO NOT cover the details needed for the Unit exam Each student is responsible for READING the TEXTBOOK for details to answer the UNIT OBJECTIVES Unit Objectives are your study guide (not this PowerPoint) Test questions cover the details of UNIT OBJECTIVES found only in your Textbook! 1  6/27/2024 Syphilis Causative organism and transmission Clinical manifestations Laboratory diagnosis Lyme disease Chapter Causative organism and transmission Overview Clinical manifestations Laboratory diagnosis Leptospirosis Causative organism and transmission Clinical manifestations Laboratory diagnosis Spirochete Diseases Spirochetes are long, slender, helically coiled bacteria containing axial filaments, or periplasmic flagella, which wind around the bacterial cell wall and are enclosed by an outer sheath. These gram-negative, microaerophilic bacteria exhibit a characteristic corkscrew flexion or motility. Diseases caused by these organisms have many similarities, including a localized skin infection that disseminates to numerous organs as the disease progresses, a latent stage, and cardiac and neurological involvement if the disease remains untreated. 2  6/27/2024 Syphilis A sexually transmitted disease caused by the spirochete bacterium Treponema pallidum Rapidly destroyed by heat, cold, and drying Direct contact with open lesion needed Transmission to fetus during pregnancy Bloodborne transmission rare Syphilis remains the most commonly acquired spirochete disease in the United States today. It is typically spread through sexual transmission. The causative agent of syphilis is Treponema pallidum, subspecies pallidum, a member of the family Spirochaetaceae. Three other pathogens in this group are so morphologically Spirochete and antigenically similar to T. pallidum that all but one are classified as subspecies. Diseases These other organisms are  T. pallidum subspecies pertenue, the agent of yaws  T. pallidum subspecies endemicum, the cause of nonvenereal endemic syphilis  T. carateum, the agent of pinta, is related but is not a subspecies of T. pallidum. 3  6/27/2024 Clinical Manifestations of Syphilis Primary stage Development of chancre Secondary stage Generalized lymphadenopathy, malaise, fever, pharyngitis, rash Latent stage Asymptomatic Tertiary stage Gummatous, cardiovascular, neurosyphilis, Tabes dorsalis (shuffling gate) http://makeagif.com/gif/shuffling-gait-QTJNRq Clinical Manifestations Treatment of Syphilis Effectively treated with antibiotics (e.g., penicillin) when detected in the early stages 4  6/27/2024 Clinical Manifestations of Syphilis Congenital syphilis Transmission of treponemes to the fetus occurs when pregnant woman has early-stage or latent syphilis Causes death in 10% of cases Live-born infants may be asymptomatic at birth but develop symptoms later runny nose, skin rash, generalized lymphadenopathy, hepatosplenomegaly, jaundice, anemia, bone abnormalities such as saddle nose or saber shins, neurosyphilis Direct detection Demonstration of treponemes in active lesions Laboratory Dark-field microscopy Diagnosis of Fluorescent antibody staining Syphilis Serological tests Nontreponemal Treponemal 5  6/27/2024 Nontreponemal Tests Detect antibody against cardiolipin (reagin), a lipid released from membranes of cells damaged as a result of the infection 1. Venereal Disease Research Laboratory (VDRL) test 2. Rapid plasma reagin (RPR) test Look for flocculation Screen: test undiluted patient serum Titer: test twofold dilutions of patient serum Patient serum mixed on a slide with cardiolipin- lecithin-cholesterol antigen suspension Rotated for 4 minutes at 180 rpm Viewed under a light microscope for flocculation VDRL Test Results compared to controls Reactive = medium to large clumps Weakly reactive = small clumps Nonreactive = no clumps or slight roughness 6  6/27/2024 RPR Test Patient serum mixed on a card with charcoal particles coated with cardiolipin antigen Rotate 8 minutes, 100 rpm Observe for macroscopic flocculation RPR Test Results 7  6/27/2024 Detect antibody to T. pallidum Fluorescent treponemal absorption (FTA-ABS) Treponemal T. pallidum particle agglutination (TP-PA) Tests Automated immunoassays Enzyme-linked immunosorbent assay (ELISA) Chemiluminescent immunoassays (CLIA) Multiplex flow immunoassays (MFI) FTA-ABS Test An indirect immunofluorescence test for antibody to T. pallidum Procedure Patient serum is incubated with sorbent (an extract of nonpathogenic treponemes) to remove cross-reacting antibodies. Absorbed patient serum is incubated with a microscope slide fixed with T. pallidum. Following a wash step, anti-human Ig conjugated with fluorescein is added. After a second incubation and wash, the slide is examined under a fluorescent microscope. No fluorescence indicates a negative test, and a result of 2+ or above is considered reactive. 8  6/27/2024 TP-PA Test Patient serum and controls are diluted and incubated with unsensitized gel particles or gel particles sensitized with T. pallidum antigen. (+) test = agglutination (smooth mat covering surface of well). (–) test = no agglutination (button). Automated ELISA for T. pallidum Antibodies A B C 9  6/27/2024 Typical Antibody Patterns in Syphilis Traditional Testing Algorithm for Syphilis 1. Screen with nontreponemal testing 2. Confirm with more specific treponemal 10  6/27/2024 Reverse Sequence Algorithm for Syphilis Screen with an automated immunoassay for T. pallidum antibody. Confirm positive results with an RPR. Perform TP-PA on samples with discrepant results. Special Diagnostic Areas Molecular testing for T. Patient monitoring pallidum DNA Polymerase chain reaction Perform nontreponemal (PCR) may be a sensitive antibody titers. alternative to dark-field Titers decline with microscopy in the future. successful treatment. 11  6/27/2024 Congenital syphilis Special Perform nontreponemal tests on Diagnostic mother and infant at birth and IgM-specific treponemal assays to Areas confirm. (continued) Neurosyphilis Perform CSF VDRL or ELISA on cerebrospinal fluid. Caused by the spirochete bacterium Borrelia burgdorferi Transmitted by Ixodes ticks Main reservoir: the white-footed mouse Lyme Disease Lyme disease is the most common vector-borne disease in the United States. 12  6/27/2024 Stage 1 Clinical Localized rash Hallmark erythema migrans Manifestations Stage 2 of Lyme Early dissemination Disease Stage 3 Late dissemination with arthritis The most prevalent neurological sign is facial palsy. Two-Tiered Testing for Lyme Disease 13  6/27/2024 Western Blot Results for B. burgdorferi Antibodies Caused by Leptospira species A zoonotic infection associated with Leptospirosis occupational and recreational activities Humans are exposed by mucous membrane contact with urine-contaminated water 14  6/27/2024 Causes febrile episode that can progress to severe disease involving renal, liver, pulmonary, and CNS Leptospirosis Laboratory testing (continued) IgM screening by ELISA, ImmunoDOT, and LFA MAT is the gold standard for confirmation. Summary Three diseases caused by spirochete bacteria are syphilis, Lyme disease, and leptospirosis. Syphilis is caused by Treponema pallidum; untreated patients may progress through four clinical stages: Primary (chancre) Secondary (lymphadenopathy, skin rash, sore throat) Latent (asymptomatic) Tertiary (granulomatous inflammation, cardiovascular disease, neurosyphilis) 15  6/27/2024 Summary (continued_1) Direct detection of T. pallidum can be performed by dark-field microscopy, fluorescence microscopy, or PCR. Nontreponemal tests such as the VDRL and RPR detect antibody to cardiolipin, a lipid released from host cells damaged during the infection; these tests are sensitive but not specific for syphilis. Summary (continued_2) Treponemal tests such as the FTA-ABS, TP-PA, and automated immunoassays are more specific because they detect antibodies to T. pallidum. Nontreponemal antibody titers decline in later stages of syphilis and during effective treatment; treponemal antibody titers appear earlier in primary syphilis and remain elevated for life. 16  6/27/2024 Summary (continued_3) In the traditional testing algorithm for syphilis, patient samples are screened with a nontreponemal test, and positive samples are confirmed with a treponemal test. In the reverse algorithm, samples are screened with an automated immunoassay for treponemal antibody and confirmed with a nontreponemal test. Summary (continued_4) Lyme disease is caused by Borrelia burgdorferi, which is transmitted by Ixodes ticks. The characteristic feature of Lyme disease is an expanding red rash that occurs at the site of the tick bite; the infection can disseminate through the body if undetected and untreated in the early stage, causing joint pain, nervous system abnormalities, and arthritis. ELISA or IFA for antibodies to B. burgdorferi are used in the initial diagnosis of Lyme disease. Confirmation of positive results is done by Western blot or another EIA. Antibodies are not detected until 3 to 6 weeks after the tick bite. 17  6/27/2024 Summary (continued_5) Leptospirosis is a zoonosis caused by exposure to water contaminated with animal urine containing leptospires. This febrile disease can progress to a severe illness that may involve renal or hepatic failure. The gold standard for confirmation of leptospirosis is the microscopic agglutination test (MAT). Postamble READ the TEXTBOOK for the details to answer the UNIT OBJECTIVES. USE THE UNIT OBJECTIVES AS A STUDY GUIDE All test questions come from detailed material found in the TEXTBOOK (Not this PowerPoint) and relate back to the Unit Objectives 18