Lecture 17 18 Bacteria Characteristics of Bacteria o Peptidoglycan cell walls o Esther linked lipids o 70S Ribosome o Circular double stranded DNA Gram Negative Bacteria Proteobacteria o Thin peptidoglycan layer o Outer membrane o LPS o More pathogenic o Five subdivisions 1 Alphaproteobacteria A Plant pathogens B Agrobacterium a a C Rhizobium D Rickettsia Inserts a plasmid into plant cells inducing tumor Fix nitrogen in the roots of plants a Obligate intracellular parasites b Arthropod borne spotted fevers c Cause typhus Rocky Mountain spotted fever 2 Betaproteobacteria Helical Examples Spirillum rhodocyclus A Spirilla a b B Neisseria C Bordetella a N meningitidis b N gonorrhoeae Rods B pertussis cause of whooping cough Causes nosocomial infections D Burkholderia 3 Gammaproteobacteria A Pseudomonadales a b a a Pseudomonas Opportunistic Metabolically adaptable Polar flagella b Azotobacer and Azomonas c Moraxella B Legionellales Legionella Found in streams warm water pipes cooling towers L pneumophilia pneumonia Coxiella Q fever transmitted via aerosols or milk Intracellular parasites C Vibrionales Found in coastal water a b Vibrio cholerae cholera c V parahaemolyticus causes gastroenteritis D Enterobacteriales Peritrichous flagella facultatively anaerobic Escherichia E coli Proteus Salmonella Yersinia causes plaque Black Death transmitted by rats 4 Deltaproteobacteria A Bdellovibrio Prey on other bacteria B Desulfovibrionales Uses sulfur instead of O2 as final electron acceptor a b a b c d e a a 5 Epsilonproteobacteria A Helicobater a Cause ulcers B Campylobacter Cause diarrhea a Gram positive bacteria o Cell wall made up thick peptidoglycan o Contain teichoic acids o Can form endospores o Wall less forms o Two major groups 1 The low GC A The bacillus class a Bacillus Aerobic Rod shaped Can produce endospores b Streptococcus fever Pharyngitis sore throat Rheumatic fever c Staphylococcus Many are pathogenic Pneumococcus and pyogenes cause scarlet Common cause of food poisoning Aureus produces endotoxins B Clostridial L monocytogenes contaminate food class d Listeria a Clostridium Obligate anaerobic Endospore forming C Perfringens causes diarrhea C Botulinum causes botulism C Tetani causes tetanus C Wall less bacteria Mollicutes a Mycoplasmas Smallest genomes Very small compared to other bacteria Only some can be cultured 2 High GC A Filamentous a Acinomyces B Streptomyces C Acid fast bacteria a Soil bacteria why soil smells a Lipophilic surface b Mycobacterium c Nocardia d Corynebacterium e Other bacterial groups Chlamydia Obligate intracellular parasites o Cannot reproduce outside their own host 3 species o Trachomatis causes STD and conjunctivitis o Psittaci causes psittacosis parrot fever o Pneumoniae causes an atypical pneumonia Life cycle 1 Elementary body non growing spore like 2 Reticulate body vegetative cell 3 Given up much of metabolism can t make ATP Spirochaetes Spiral organisms with a sheath axial filaments Slow growing aquatic free living or parasitic Several human pathogens o Treponema pallidum o Borrelia burgdorferi syphilis lyme disease Lecture 19 Principle of disease and epidemiology Principles of Disease and Epidemiology o Disease o Etiology o Infection Koch s postulate o 4 steps Lack of ease An abnormal state in which the body is not functioning normally The study of the cause of a disease Growing and multiplying of pathogens in the host 1 Detect pathogen 2 3 4 Re isolate in pure culture Isolate in pure culture of pathogen Induce in new host o Exceptions Some pathogens can cause several disease conditions or the same pathogen can cause different disease symptoms Some pathogens cause disease only in humans Some pathogens need cofactors not all develop disease Development of some diseases takes years Reservoirs of infection o Human Carriers may have inapparent infections or latent diseases Ex AIDS o Animal o Nonliving Zoonoses may be transmitted to humans Ex rabies Present in soil or water Ex Botulism tetanus Transmission of disease o Contact Direct Touching kissing sexual intercourse Indirect Droplet Fomites Sneezing o Vehicle o Vectors Inanimate reservoir Ex Foodborne illness Arthropods especially fleas ticks and mosquitoes Mechanical Biological History of Epidemology carries pathogen on feet Pathogen reproduces in vector o John Snow o Florence Nightingale Mapped the occurrence of Cholera in London English nurse writer and statistician Showed that improved sanitation decreased the incidence of Showed that hand washing decreased the incidence of puerperal epidemic typhus o Ignaz Semmelweis fever CDC o Located in Atlanta o Collects information focused on Morbidity Mortality Incidence of a specific notifiable disease Deaths from notifiable diseases Lecture 20 Nosocomial Infections and Emerging Infectious Diseases EIDs Nosocomial disease o Infection occurs in hospital o Occurs due to compromised immune systems of hosts increased microorganisms in hospital and chain of transmission from staff to patients o Prevention and control Barriers and cleanliness Isolation and quarantine Aseptic techniques disinfection and sterilization Surveillance and the infection control committee Emerging infectious diseases o Increasing and likely to increase o Contributing factors Human demographics behavior vulnerability More people more crowding Technology and industry Mass producing foods Use of antibiotics in food animals creating antibiotic resistant bacteria More organ transplants and blood transfusions New drugs in humans that prolong immunosuppression Economic development land use changing ecosystems Human s changing ecology influencing transmission o Dams deforestation Contaminated water More exposure to wild animals and vectors International travel and commerce People travel much more and can pick up diseases Food is imported from other countries Microbial adaptation and change Increase antibiotic resistance with use in animals and humans Species jump from animals to humans Poverty social inequality breakdown of public health measures Lack of basic hygiene infrastructure Inadequate vaccinations Lecture 21 22 Pathology study of disease o Pathogenicity Ability to cause disease o Virulence Degree of pathogenicity o Virulence factors Toxin capsules and fimbiae o Infection and disease Exposure and infection Disease and damage to the host toxicity Infectivity and virulence o ID50 Infectious dose for 50 of test population o LD50 Lethal dose of a toxin for 50 of the test population
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