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Published on October 9, 2007

Author: Margot

Source: authorstream.com

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Mike Ferris:  Mike Ferris Back ground Assistant Professor, LSU Microbiology Research Institute for Children, New Orleans 896-2736 Mferris@chnola-research.org B.S. - dept. of microbiology, Pennsylvania State Uuniversity Ph.D. - dept. of molecular and cell biology, Montana State University ecology of hot spring microbial mat communities PostDoc - Scripps Institute of Marine Biology, La Jolla, CA Current research - Polymicrobial Diseases - cultivation-independent analysis bacterial flora associated with Bacterial Vaginosis Bug Parade:  Bug Parade Determinative Microbiology Bacteria identified by, cell shape, Gram stain, growth temperature, spores, motility, carbon source utilization, nutrient requirements, anaeribic, etc. Sufficient for previously described cultivated species The physician can assess pathogenicity and select treatment Scientifically insufficient Does not help us understand most prokaryotes, most are uncultivated Does not permit us to infer properties of new isolates from known isolates Does not permit studies of the origin and evolution of cellular functions, such as drug resistance. Polymicrobial diseases such as Bacterial Vaginosis cannot be adequately addressed using a determinative system Prokaryotes and Eukaryotic protists are routinely classified by genetic sequence analysis Advantageous, pathogenic microbes can be detected, identified and related to other species without cultivation Can reveal novel species previously not associated with disease. Atopobium viginae, metronidazole resistance, BV? Slide3:  Murray: Chapters 33 and 35 Legionnella & other Gram-Negative Bacteria :  Legionnella & other Gram-Negative Bacteria Dr. Adele Spence/Mike Ferris MIP 2003 Chapter 35 Grouped By Diseases:  Grouped By Diseases Legionnaires’ Disease and Pontiac Fever Legionella sp. Rat Bite Fever Spirillum minus and Streptobacillus moniliformis Opportunistic Infections Cardiobacterium hominis Eikenella corrodens Kingella sp. Granuloma Inguinale Calymmatobacterium granulomatis Cat Scratch Disease and Trench Fever Bartenella henselae and B. quintana Genus Legionellae:  Genus Legionellae Legionellae are ubiquitous, aquatic saprophytes They are slender, Gram-negative coccobacilli that tend to be pleomorphic DO NOT stain well with Gram stain In tissue Dieterle’s silver stain is used Cause of Legionnaires’ disease and Pontiac fever DiseasesCaused by Legionella pneumophilis:  DiseasesCaused by Legionella pneumophilis Legionnaires’ disease A severe sometimes fatal form of pneumonia Pontiac Fever A self-limiting febrile illness characterized by fever, chills, myalgia, malaise and headache Comparison of Legionnaires’ disease and Pontiac fever:  Comparison of Legionnaires’ disease and Pontiac fever Legionnaires’ disease A severe sometimes fatal form of pneumonia 95% of cases due to L. pneumophilia Other cases due to L. micdadei *and other Legionella sp. Patients usually somewhat immunocompromised Pontiac Fever A self-limiting febrile illness characterized by fever, chills, myalgia, malaise and headache Caused by L. pneumophilia Patients usually immunocompetent _____________________________________________________________________L. micdadei is also weakly acid-fast. Slide9:  Comparison of Diseases Caused by Legionella From Murray, Medical Microbiology, 3rd ed. Legionnaires’ Disease:  Legionnaires’ Disease Incubation period 2 to 10 days after exposure to contaminated water Signs and symptoms appear abruptly Fever, chills, a dry, nonproductive cough , headache Primary manifestation is pneumonia with multi-lobe consolidation Without early treatment, leads to multisystem failure and death Epidemiology:  Epidemiology Estimated 25,000 cases per year Mortality about 20% Not passed person-to-person Community-acquired Natural bodies of water Exposure to contaminated water (automated misting devices; AC water towers) Hospital-acquired (nosocomial) In water supplies, shower heads Most at Risk:  Most at Risk Individuals with compromised cellular immunity Elderly Longtime smokers Individuals with chronic bronchitis or emphysema Transplant patients Habitat of L. pneumophilia :  Habitat of L. pneumophilia Legionella are free- living in surface waters of rivers and lakes Organism infect and multiply in free- living aquatic ameoba who also inhabit these waters (Legionella in amoeba >) amoeba Pathogenicity:  Pathogenicity Portal of Entry Inhalation of droplets from contaminated water Bacterial growth, activation of complement, and death of alveolar macrophages produce powerful chemotactic factors that elicit an influx of monocytes and PMNs The result is a destructive pneumonia that obliterated the air spaces and compromises respiratory function Slide15:  We detected these 16S rRNA sequences by PCR in a pH 2.5 geothermal spring in the Norris Geyser Basin of Yellow- stone National Park. What can be inferred about the the organisms that harbor the sequences based on their % similarities to those of cultivated species? The Park Service asks you to comment on possible health risks to senior citizen tour groups from the constant aerosols produced by geothermal activity and recreational use of hot pools. What’s your advice? Virulence Factors:  Virulence Factors Facultative intracellular parasite Bind C3b to bacterial cell and attach to CR3 receptors on host cells After phagocytosis, phagosome fusion with lysosome is inhibited Bacteria multiply in vacuoles; their proteolytic enzymes kill host cells and bacteria are free to invade other cells Phagocytosis of Complement(C3b) Bound Legionella:  Phagocytosis of Complement(C3b) Bound Legionella Multiplication of B-Cell Immunity Not Protective:  B-Cell Immunity Not Protective Lysis of cells T-Cell Mediated Response Is Protective:  T-Cell Mediated Response Is Protective No multiplication Host Defense:  Host Defense Immunocompetent Probably have very mild and flu-like symptoms resolve within a week Functional CMI; Th1 and activated macrophages Immunocompromised Preexisting respiratory problems Elderly, smokers, transplant patient Defective CMI Differential Diagnosis:  Differential Diagnosis Other atypical pneumonias (Mycoplasma, viral pneumonias, psittacosis, and Q fever Other community-acquired pneumonias Pneumococcal (endogenous) Staphylococcal, Hemophilus, mycoplasmal Laboratory Diagnosis:  Laboratory Diagnosis Gram stain from clinical material is not very effective. Silver stain (Dieterle) may be useful Direct Fluorescent Antibody (DFA) Culture on BCYE (buffered charcoal yeast extract) Immunoassay Antigen detection in patient urine or tissues Acute and convalescent serum (Indirect Fluorescent Antibody) Treatment and Control:  Treatment and Control Treatment Erythromycin is treatment of choice Rifampin or fluoroquinolones Control Identification of the environmental source and reduction of microbes In hospital settings Hyperclorination of water supply Increasing temperature of heated water Question 1:  Question 1 Which of the following is mis-matched regarding these Gram-negative rods? a. Bartenella henselae -- Cat scratch disease b. Streptobacillli moniliformis -- rat bite fever c. Spirillum minor – Pontiac fever d. Eikenella corrodens -- infection following a fist fight e. Calymmatobacterium granulomatis -- Donovan bodies are diagnostic Question 2:  Question 2 All of the following are true regarding Legionnaires’ disease EXCEPT: a. At risk individuals include elderly smokers with chronic bronchitis or emphysema b. Host defense for this atypical pneumonia is cell mediated via Th1 cells (activated macrophages) c. Super heating water is detrimental to L. pneumophilia d. Bacterial attachment to host cells is via the complement (CR3) receptor e. Organisms are characteristically passed from person to person via respiratory secretions. Slide26:  Happy Thanksgiving!

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