Bordetella, Francisella & Brucella
General Overview of Bordetella, Francisella & Brucella Ø Extremely small Ø Aerobic nonfermenters Ø Gram-negative coccobacilli Ø True pathogens: isolation always associated with disease; i. e. , always clinically significant NOTE: Previously studied nonfermenters were all opportunistic pathogens
Human Disease & Associated Pathogens Genus Species Disease pertussis Pertussis parapertussis Pertussis (milder form) bronchiseptica Bronchopulmonary disease Francisella tularensis Tularemia Bordetella Brucella melintensis abortus suis canis Brucellosis
Bordetella pertussis
Epidemiology of Bordetella pertussis Infection Ø Man is only natural host; obligate parasites of man Ø Disease is highly communicable (highly infectious) Ø Person-to-person spread via inhalation of infectious aerosols Ø Incidence in U. S. A. significantly reduced with required DPT vaccine; Incidence increasing as some local school boards stop requirement Ø Children under one year at highest risk, but prevalence increasing in older children and adults
Incidence & Severity of Pertussis Cases in USA
Incidence of Pertussis in USA
Age Distribution & Severity of Pertussis Cases
Changes in Age Distribution for Pertussis Cases Blue = 1988 Orange = 1998
Clinical Progression of Pertussis , Inflammation of respiratory mucosal memb. Most infectious, but generally not yet diagnosed or death
Virulence Factors Associated with Bordetella pertussis Ø Fimbriae not primarily involved in adherence; Exotoxin & hemagglutinin mediate attachment specifically to ciliated epithelium of bronchial tree Ø Cells multiply among cilia of epithelial cells and produce filamentous hemaglutinin and classic A-B exotoxin and other toxins leading to localized tissue damage and systemic toxicity · Pertussis toxin, adenylate cyclase toxin, tracheal cytotoxin, dermonecrotic toxin, filamentous hemagglutinin, LPS (lipid A & lipid X) Ø Classical A-B exotoxin has three distinct activities · Histamine sensitizing factor · Lymphocytosis promoting factor · Islet activating protein
Virulence Factors Associated with Bordetella pertussis
Laboratory Culture, Prevention & Treatment of Bordetella Ø Nonmotile Ø Fastidious and slow-growing · Requires nicotinamide and charcoal, starch, blood, or albumin to absorb toxic substances · Requires prolonged growth · Isolated on modified Bordet-Gengou agar Ø Inactivated whole bacterial cells and toxoid are prepared in formalin for inclusion in DPT vaccine Ø Subunit (acellular) vaccine also available Ø Treatment with erythromycin, suction, oxygen Ø Treatment does not eliminate symptoms
Differential Characteristics of Bordetella Species
Francisella tularensis
Francisella tularensis Infections
Francisella tularensis Infections (cont. )
Clinical Presentation of Tularemia NOTE: Also Gastrointestinal & Pneumonic forms of disease
Epidemiology of F. tularensis Infection Ø Rabbits, ticks & muskrats are main reservoirs in US Ø Two biochemical varieties • F. tularensis bv. tularensis (a. k. a. , Jellison Type A) • F. tularensis bv. palaearctica (a. k. a. , Jellison Type A) Ø Jellison Type A strains are the major biovar associated with severe disease in North America • Most commonly, transmission by tick vectors from rabbit reservoirs or direct contact with rabbits
Biochemical Variants (Biovar) of Francisella tularensis
Virulence Factors of Fransicella tularensis Ø Antiphagocytic capsule • Thin lipid capsule present in pathogenic strains Ø Facultative intracellular parasite that can survive in macrophages of the reticuloendothelial system
Laboratory Culture, Prevention & Treatment of F. tularensis Ø Nonmotile Ø Fastidious and slow-growing · Requires cysteine-supplemented specialized media wi · Requires prolonged growth Ø Disease prevention: • Avoidance of reservoirs and vectors • Protective clothing and gloves • Laboratory personnel should be made aware of potential for Fransicella in clinical specimens
Antibody Response to Francisella tularensis Infections
Brucella spp.
Brucella Infections
Brucella Infections (cont. )
Epidemiology of Brucellosis Ø Animals are natural reservoir • Cattle, goats, sheep, swine, bison, elk, dogs, foxes, coyotes Ø 500, 000 human cases per year worldwide Ø Less than 100 annual cases in the U. S. due to successful control of the disease in livestock and the animal reservoir Ø Transmission via i) ingestion of contaminated milk or cheese, or ii) direct contact with infected animals or animal products Ø Because it can be transmitted to humans, brucellosis is one of the most regulated diseases of cattle in the U. S.
Incidence of Brucellosis in USA
Brucellosis in Animals Ø Brucella infect organs rich in erythritol (a sugar metabolized in preference to glucose) like breast, uterus, placenta and epididymis (tube that connects a pair of ducts that conduct spermatozoa during ejaculation) Ø Asymptomatic carriage, sterility or abortions Ø Transmitted between animals in aborted tissues
Human Brucellosis & Associated Species Severe
Brucellosis in Humans Ø Reportable disease Ø Human brucellosis = Bang's disease, named for Bernhard Bang & Sir David Bruce who discovered Brucella Ø Facultative intracellular pathogens of mononuclearphagocyte system (formerly reticuloendothelial system which is involved in immune defense against microbial infection and removal of worn-out blood cells) • Bacteria are phagocytosed by macrophage or polymorphonuclear leukocyte • Survive intracellularly by inhibiting killing • Carried to spleen, liver, bone marrow, lymph nodes, kidneys Ø Form granulomas (mass of granulation tissue produced in response to chronic infections, inflammation, or foreign bodies) and cause destructive tissue damage
Brucellosis in Humans (cont. ) Ø Consumption of contaminated unpasteurized milk or direct contact with infected animal reservoir • Disease associated with contact with infected cattle, cattle products, or dogs is a milder form • Disease associated with contact with goats and sheep is acute and severe with complications common • Disease associated with contact with swine is chronic & suppurative with destructive lesions and localization in cells of the reticuloendothelial system (RES) Ø Occupational hazard of laboratory personnel, veterinarians, farm workers, and meat handlers at risk through direct contact or inhalation Ø Protective clothing for abattoir workers, avoidance of unpasteurized dairy products Ø Highest numbers of cases reported in CA and TX
Clinical Presentation of Human Brucellosis Ø Acute disease often develops with initial nonspecific symptoms of malaise, chills, fatigue, weakness, myalgias (muscles), weight loss, arthralgias (joint), and nonproductive cough Ø Mild disease with rare suppurative complications Ø Chronic disease and recurrence are common because it can survive in phagocytic cells and multiply to high concentrations Ø May also take the form of destructive lesions
Diagnosis & Treatment of Human Brucellosis Ø Plate agglutination test (a. k. a. , Brucella ring test) diagnosing Brucella • Drop of serum mixed with drop of Brucella antigen • Clumping indicates infection • If the mixture remains clear, the result is negative. Ø Treated with combination of tetracycline and doxycycline Ø For infants, tetracycline is toxic, so children are treated with trimethoprim-sulfamethoxazole.
Control & Prevention of Brucellosis Ø In 1934, the U. S. Department of Agriculture (USDA) established the National Brucellosis Eradication Effort which is managed by Animal, Plant, and Health Inspection Service (APHIS) Ø APHIS certifies states as brucellosis-free, classes A, B, or C of which all states are currently classified A Ø Serology & confirmatory bacterial culture to identify infected animals Ø Positive animals/herds are destroyed Ø Vaccination is available but is not a 100% effective and is costly to cattle ranchers
REVIEW Bordetella, Francisella & Brucella
General Overview of Bordetella, Francisella & Brucella Ø Extremely small Ø Aerobic nonfermenters Ø Gram-negative coccobacilli Ø True pathogens: isolation always associated with disease; i. e. , always clinically significant NOTE: Previously studied nonfermenters were all opportunistic pathogens REVIEW
Human Disease & Associated Pathogens Genus Species Disease pertussis Pertussis parapertussis Pertussis (milder form) bronchiseptica Bronchopulmonary disease Francisella tularensis Tularemia Bordetella Brucella melintensis abortus suis canis Brucellosis REVIEW
Review of Bordetella pertussis
Bordetella pertussis Infections REVIEW
Bordetella pertussis Infections (cont. ) REVIEW
Epidemiology of Bordetella pertussis Infection Ø Man is only natural host; obligate parasites of man Ø Disease is highly communicable (highly infectious) Ø Person-to-person spread via inhalation of infectious aerosols Ø Incidence in U. S. A. significantly reduced with required DPT vaccine; Incidence increasing as some local school boards stop requirement Ø Children under one year at highest risk, but prevalence increasing in older children and adults REVIEW
Changes in Age Distribution for Pertussis Cases Blue = 1988 Orange = 1998 REVIEW
Clinical Progression of Pertussis , Inflammation of respiratory mucosal memb. Most infectious, but generally not yet diagnosed or death REVIEW
Virulence Factors Associated with Bordetella pertussis REVIEW
Review of Francisella tularensis
Francisella tularensis Infections REVIEW
Francisella tularensis Infections (cont. ) REVIEW
Clinical Presentation of Tularemia NOTE: Also Gastrointestinal & Pneumonic forms of disease REVIEW
Epidemiology of F. tularensis Infection Ø Rabbits, ticks & muskrats are main reservoirs in US Ø Two biochemical varieties • F. tularensis bv. tularensis (a. k. a. , Jellison Type A) • F. tularensis bv. palaearctica (a. k. a. , Jellison Type A) Ø Jellison Type A strains are the major biovar associated with severe disease in North America • Most commonly, transmission by tick vectors from rabbit reservoirs or direct contact with rabbits REVIEW
Biochemical Variants (Biovar) of Francisella tularensis REVIEW
Review of Brucella spp.
Brucella Infections REVIEW
Brucella Infections (cont. ) REVIEW
Epidemiology of Brucellosis Ø Animals are natural reservoir • Cattle, goats, sheep, swine, bison, elk, dogs, foxes, coyotes Ø 500, 000 human cases per year worldwide Ø Less than 100 annual cases in the U. S. due to successful control of the disease in livestock and the animal reservoir Ø Transmission via i) ingestion of contaminated milk or cheese, or ii) direct contact with infected animals or animal products Ø Because it can be transmitted to humans, brucellosis is one of the most regulated diseases of cattle in the U. S. REVIEW
Brucellosis in Animals Ø Brucella infect organs rich in erythritol (a sugar metabolized in preference to glucose) like breast, uterus, placenta and epididymis (tube that connects a pair of ducts that conduct spermatozoa during ejaculation) Ø Asymptomatic carriage, sterility or abortions Ø Transmitted between animals in aborted tissues REVIEW
Human Brucellosis & Associated Species Severe REVIEW
Brucellosis in Humans Ø Reportable disease Ø Human brucellosis = Bang's disease, named for Bernhard Bang & Sir David Bruce who discovered Brucella Ø Facultative intracellular pathogens of mononuclearphagocyte system (formerly reticuloendothelial system which is involved in immune defense against microbial infection and removal of worn-out blood cells) • Bacteria are phagocytosed by macrophage or polymorphonuclear leukocyte • Survive intracellularly by inhibiting killing • Carried to spleen, liver, bone marrow, lymph nodes, kidneys Ø Form granulomas (mass of granulation tissue produced in response to chronic infections, inflammation, or foreign bodies) and cause destructive tissue damage REVIEW
Brucellosis in Humans (cont. ) Ø Consumption of contaminated unpasteurized milk or direct contact with infected animal reservoir • Disease associated with contact with infected cattle, cattle products, or dogs is a milder form • Disease associated with contact with goats and sheep is acute and severe with complications common • Disease associated with contact with swine is chronic & suppurative with destructive lesions and localization in cells of the reticuloendothelial system (RES) Ø Occupational hazard of laboratory personnel, veterinarians, farm workers, and meat handlers at risk through direct contact or inhalation Ø Protective clothing for abattoir workers, avoidance of unpasteurized dairy products Ø Highest numbers of cases reported in CA and TX REVIEW
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