Gram-Negative Bacteria PDF

MISCELLANEOUS…BUT IMPORTANT GRAM NEGATIVE BACTERIA Suzie Hingley-Wilson Lecturer in Bacteriology  Learning outcomes Describe the transmission, epidemiology, and diseases caused by Legionella sp Bordetella pertussis Gram-negative obligate anaerobes  MISCELLA...

MISCELLANEOUS…BUT IMPORTANT GRAM NEGATIVE BACTERIA Suzie Hingley-Wilson Lecturer in Bacteriology  Learning outcomes Describe the transmission, epidemiology, and diseases caused by Legionella sp Bordetella pertussis Gram-negative obligate anaerobes  MISCELLANEOUS BUT IMPORTANT GRAM NEGATIVE BACTERIA Fastidious Gram-negative Rods: Legionella pneumophila: Legionaire’s Disease Bordetella pertussis: Whooping Cough Haemophilus influenzae: meningitis and septicaemia in children < 6 months Gram-negative obligate anaerobes (very diverse group): Bacteroides Fusobacterium Prevotella Porphyromonas  LEGIONELLA PNEUMOPHILA: 1st OUTBREAK Bellevue-Stratford Hotel, Broad St, Philadelphia The 58th State Convention of the American Legion of Pennsylvania, July 1976, 4000 World War II Legionnaires, + their families and friends, ~600 staying at the hotel at which the convention is hosted. On day two of the convention Legionnaires began to fall ill….chest pains, breathlessness… Eventually 34 die, 221 ill (…72 walking past lobby) Epidemiological evidence suggested exposure in lobby CDC feared terrorist plot Rickettsiologist Dr Joseph McDade 1977..innoculated guinea pigs with material from deceased and noted these fastidious bacilli within macrophages  LEGIONELLA PNEUMOPHILA Ulber R., et al., 2014 Dr Carl Fliermans…… L. pneumophila lipids resembled those of the thermophilic bacteria in Yellowstone National Park, and that this bacteria tended to live as biofilm Discovered the bacteria in thermal waters discharged from nuclear reactor at Savannah River Laboratory. Later in natural hot springs, air-conditioning systems and cooling towers LEGIONELLA: PHYLOGENY  CHARACTERISTICS OF THE GENUS LEGIONELLA Type species is Legionella pneumophila 42 species characterised, 18 associated with human illness, LP 85% of cases Non-spore forming, Gram-negative rods that vary from short thin forms to longer filamentous forms Most species motile via a single polar flagellum Aerobic Grow in tap water and water but in artificial media are nutritionally fastidious !  Key facts (W.H.O. 2019) Legionellosis The most common form of transmission of Legionella is inhalation of contaminated aerosols produced in conjunction with water sprays, jets or mists. Infection can also occur by aspiration of contaminated water or ice, particularly in susceptible hospital patients. Legionnaires’ disease has an incubation period of 2 to 10 days (but up to 16 days has been recorded in some outbreaks). Death occurs through progressive pneumonia with respiratory failure and/or shock and multi-organ failure. Untreated Legionnaires’ disease usually worsens during the first week. Of the reported cases 75–80% are over 50 years and 60–70% are male. Community, travel or hospital acquired  LEGIONNAIRE’S DISEASE Acute pneumonia. Bacterium multiplies in alveolar macrophages Produce cytokines that elicit an influx of monocytes and polymorphonuclear cells Obliteration of the air spaces compromises respiratory function Fevers, Cough, Breathlessness Kaufmann  LEGIONELLA IN THE ENVIRONMENT Only documented source of Legionella species is water Found naturally in the freshwater of streams, lakes, warm springs, rivers, and riverbanks Intracellular parasite of amoeba and other protozoa: protects against chlorine, drying and heat Modifying our environment to suit ourselves has unexpectedly created ideal conditions for Legionella growth Many artificial water systems are an ideal environment for its growth (temperature and stagnation) CHAIN OF CAUSATION FOR LEGIONELLA INFECTION Environmental Reservoir Multiplication (stagnation, temperature nutrients) Dissemination by aerosol generation (running tap, shower, toilet flush, spraying flowers, jacuzzis, cooling towers etc) Inhalation into lungs by susceptible host (age, sex, etc) ????? New evidence suggests that Aspiration is the most common way that Legionella enter into the lungs since the protective mechanisms to prevent aspiration BORDETELLA PERTUSSIS BORDETELLA PERTUSSIS: PHYLOGENY The order Burkholderiales currently contains: Burkholderia Bordetella Ralstonia BORDETELLA PERTUSSIS:GENERAL CHARACTERISTICS Aerobic, Gram negative, small coccobacillus Specific only to humans Colonizes the respiratory tract to cause Whooping Cough (Pertussis) Today, whooping cough still effects 20-40 million people worldwide/year and causes between 200,000- 400,000 fatalities  BORDETELLA PERTUSSIS: DISEASE Transmission via droplets/inhalation Colonization of upper respiratory tract, production of toxins Incubation period: 5-10 days Catarrhal stage: ~ 1-2 weeks rhinorrhoea and mild cough Paroxysmal stage: ~1-6 weeks , can go on for 6 months, 5-20 forceful, hacking successive coughs, title time for breathing, whoop when air rushes back into the lungs Vomiting and frequent coughing exhausts child http://www.huffingtonpost.co.uk/2015/11/16/whooping- cough-vaccination-baby-coughing-video_n_8574938.html Complications - pneumonia, otitis media, asthma BORDETELLA PERTUSSIS: EPIDEMIOLOGY BORDETELLA PERTUSSIS: EPIDEMIOLOGY  BORDETELLA PERTUSSIS: EPIDEMIOLOGY Increased awareness & better detection methods Waning immunity as many cases are in older children and adults? Acellular vaccines provide a shorter duration of protection? Vaccine research ongoing…correlate of protection? COVID-19?  GRAM-NEGATIVE OBLIGATE ANAEROBES Colonise the human body’s anaerobic environments in huge numbers (large bowel) Predominant bacteria in upper respiratory tract, GI and GU tract Outnumber aerobic bacteria by 10-100 fold Ulber R., et al., 2014 Many species, but few pathogens Clinical Diseases Periodontal infections Abscess Intra-abdominal infections Gynecological infections K. Lougheed Skin and soft tissue Bacteriodes fragilis is associated with 80% of intra-abdominal infections Often polymicrobial infections  GRAM-NEGATIVE OBLIGATE ANAEROBES Bacteriodes: most commonly found anaerobes, intra-abdominal infections and abcesses, eg. B. fragilis Acute nectrotizing gingivitis: Caused by a mixed bacterial infection that includes anaerobes such as Prevotella, Fusobacterium and spirochetes, such as Treponema  FURTHER READING: Legionella and Bordetella Khodr et al., Molecular epidemiology, phylogeny and evolution of Legionella. Infection, Genetics and Evolution 43 (2016) 108–122 Nieves and Heininger. Bordetella pertussis. Microbiol Spectr. 2016 Jun;4(3) doi: 10.1128/microbiolspec.EI10-0008-2015. Thankyou to Simon Park. Images from shutterstock or giantmicrobes unless otherwise noted. Thank you for listening and taking part. Any further questions…