Chapter 11 micro
- 1. Chapter 11: The Prokaryotes Domains Bacteria and Archaea
- 2. The Proteobacteria – largest of the bacterial lineages (chart pg 314) Includes most of the gram neg. chemoheterotrophic bacteria Chemoheterotrophs = use organic molecules as a source of carbon and energy Some of the major subgroups include: Enteric bacteria (Order Enterobacteriales) Gram neg. rods, peritrichous flagella, facultative anaerobes Most inhabit mammalian intestinal tract and consume O2 and maintain anaerobic conditions of intestinal tract
- 3. Enteric bacteria E. coli – normal intestinal bacteria , not usually pathogenic but some can cause urinary tract infections , traveler’s diarrhea, or a foodborne disease caused by E. coli O157:H7 Presence in H2O/food is indication of fecal contamination Salmonella – all potentially pathogenic Common inhabitants of intestinal tracts of poultry and cattle
- 4. Enteric bacteria Salmonella cont. Under unsanitary conditions they can contaminate food Salmonella that infect warm blooded animals considered a single species – Salmonella enterica – divided into 2400 serovars (serotypes) Serovars can be further differentiated by biochemical or physiological properties into biovars or biotypes Salmonella typhi – typhoid fever the most severe illness of Salmonella Salmonellosis – less severe g astro i ntestinal disease
- 5. Enteric bacteria Shigella – human pathogen Responsible for bacillary dysentery = shigellosis Found only in humans 2 nd only to E. coli as a cause of traveler’s diarrhea Some strains cause life threatening dysentery
- 6. Enteric bacteria Yersinia – human pathogen Yersinia pestis – plague , Black Death of Medieval Europe Urban rats and ground squirrels carry the bacteria but fleas usually transmit the organism among animals and humans Transmission can be from respiratory droplets of infected animals or people
- 7. Enteric bacteria Citrobacter – opportunistic pathogen – urinary tract Enterobacter – opportunistic pathogen Enterobacter cloacae and Enterobacter aerogenes cause urinary tract infections and hospital acquired infections Widely distributed in humans, water, sewage, and soil
- 8. Enteric bacteria Serratia – opportunistic pathogen Serratia marcescens – produces red pigment In hospitals found on catheters, in saline irrigation solutions and other sterile solutions Cause of many urinary and respiratory tract i nfections in hospitals Because of red pigment of the colonies it was used in the past to check for wind currents that might carry bioweapons
- 9. Enteric bacteria Serratia cont. Balloons filled with broth cultures of Serratia marcescens were burst at a given point and open plates of nutrient agar were set out for a specific time period at numerous points If bright red colonies appeared on any of the plates after incubation, that was evidence that bacteria released by a bioterrorist could travel from the starting point to that point Pathogenic Serratia marcescens are now known to exist so tests are no longer done
- 10. Vibrio group Order Vibrionales – closely related group to enteric bacteria but are generally free living marine or estuarine organisms Vibrios – facultative anaerobes, G neg. curved motile rods Vibrio cholerae – cholera- profuse and watery diarrhea Vibrio parahaemolyticus – inhabits coastal salt H2O and is transmitted to humans by raw or undercooked shellfish - gastroenteritis
- 11. Pseudomonads Order Pseudomonadales Pseudomonas – aerobic, G neg., motile rods Pseudomonads excrete extracellular, water soluble pigments into their media ( blue green) Pseudomonas aeruginosa infects urinary tract, burns, wounds , and can cause blood infections, abscesses, and meningitis in weakened pxs
- 12. Pseudomonads Pseudomonas cont. in hospitals and places where pharmaceutical agents are prepared, they grow on minute traces of unusual carbon sources Ex. Soap residue or cap liner adhesives Grow in some antiseptics Resistance to most Abs - medical concern Responsible for 10 % of the nosocomial infections esp. in burn units
- 13. Pseudomonads Persons with cystic fibrosis are prone to Pseudomonas infections Can grow at refrigerator temperatures and cause food spoilage Azobacter and Azomonas are pseudomonad that live in the soil and fix nitrogen
- 14. Order Rickettsiales Rickettsia Obligate intracellular parasites that reproduce only in a mammalian cell G neg., rod or Coccobacilli Transmitted to humans thru bites of ticks, lice or fleas where they enter their hosts cell by inducing phagocytosis and enter the cytoplasm and begin reproducing by binary fission Responsible for a # of diseases known as the spotted fever group
- 15. Order Rickettsiales Spotted fever group Epidemic typhus – Rickettsia prowazekii –transmitted by lice Endemic murine typhus – Rickettsia typhi – transmitted by rat fleas Rocky Mt. spotted fever – Rickettsia rickettsii – transmitted by ticks Rickettsial infections damage the permeability of blood capillaries wh/ results in the characteristic spotted rash
- 16. Order Rickettsiales Ehrlichia G neg., rickettsial like bacteria Live within WBCs as obligate intracellular parasites Transmitted by ticks and cause ehrlichiosis Sx = high fever, Has, ms pain, leukopenia Sometimes fatal
- 17. Proteobacteria Order Bukholderiales Bordetella – nonmotile, aerobic, G neg. rod Bordetella pertussis – pertussis or whooping cough Order Neisseriales Neisseria – aerobic, G neg. cocci that inhabit mucous membranes of mammals Neisseria gonorrhoeae – gonorrhea Neisseria meningitidis – meningococcal meningitis
- 18. Order Legionellales Legionella Common in streams and they colonize warm water supply lines in hospitals and water in the cooling towers of air conditioning systems Isolated during an outbreak of pneumonia = legionellosis An ability to survive and reproduce in aquatic amoebae makes them difficult to eradicate in H2O systems Coxiella – obligate intracellular pathogen (needs host cell to reproduce) Coxiella burnetii – Q fever Transmitted to cattle by ticks and to humans by contact or aerosols
- 19. Order Pastuerellales Pasteurella – pathogen of domestic animals Pasteurella multocida can be transmitted to humans by dog and cat bites Found in saliva of the Komodo dragons and death of it’s prey is from the bacteria Haemophilus - inhabit the mucous membranes of the upper respiratory tract, mouth, vagina, and intestinal tract
- 20. Order Pastuerellales Haemophilus influenzae – cause of meningitis in young children, ear aches, epiglotitis (inflamed epiglottis – life threatening), septic arthritis in children, bronchitis and pneumonia Haemophilus ducreyi – sexually transmitted disease chancroid
- 21. Order Campylobacterales Campylobacter – microaerophilic vibrios, each cell has 1 polar flagella Campylobacter jejuni leading cause of food borne intestinal disease Helicobacter - microaerophilic curved rods with multiple flagella Helicobacter pylori – peptic ulcers and stomach cancer in humans
- 22. Genera Campylobacter & Helicobacter These are curved (helical), Gram-negative, microaerophilic rods. Campylobacter jejuni is an important food- and waterborne cause of diarrheal disease. Helicobacter pylori is the cause of stomach ulcers as well as the development of stomach cancer.
- 23. G + Bacteria are divided into Firmicutes and Actinobacteria Firmicutes – low GC species = low guanine - cytosine ratio compared to adenine – thymine ratio Endospore forming rods – ability to form a dormant spore highly resistant to UV irradiation and desiccation and other environmental hazards Clostridium – obligate anaerobes Rod shaped cells that contain endospores that distend the cell walls Endospores are important to medicine and food industry – endospores are resistant to heat and chemicals
- 24. Firmicutes Clostridium cont. Clostridium tetani – tetanus Clostridium botulinum – botulism Clostridium perfringens – gas gangrene, food borne diarrhea Clostridium difficile – serious diarrhea – from Ab therapy wh/ alters normal microbiota allowing overgrowth of C. difficile
- 25. Firmicutes Bacillus – rods that produce endospores, common in soil, several produce Abs Bacillus anthracis – non motile facultative anaerobe, forms chains in culture Causes anthrax – disease of cattle, sheep, horses that can be transmitted to humans Centrally located endospore does not distend the cell walls Poss. Agent of warfare Bacillus cereus – common in environment and can cause food poisoning esp in starchy food – ex. rice
- 26. Non spore forming Firmicutes Mycoplasma – submicroscopic bacteria that lack a cell wall Cells very small – 0.1-0.25 um wh/ allow them to pass thru filters that retain bacteria, use to think they were a virus Smallest self replicating organism capable of cell free existence Mycoplasma pneumoniae – mild pneumonia Contaminant of cell cultures
- 27. Genus Mycoplasma Members of genus Mycoplasma lack cell walls and consequently are pleiomorphic and able to pass through filters that can trap cell-wall containing bacteria. Mycoplasma pneumoniae is the cause of Walking Pneumoniae. Note the “fried egg” appearance of Mycoplasma colonies.
- 28. Non spore forming Firmicutes Staphylococcus – grape like clusters, facultative anaerobes Staphlycoccus aureus = golden, yellow colonies Grow well under high osmotic pressure and low moisture conditions- can grow on foods with high osmotic pressure – ham, cured meats Found in our noses and on skin
- 29. Non spore forming Firmicutes Staphylococcus cont. Produces many toxins and it’s ability to develop resistance quickly to Abs Ex. Penicillin contributes to its pathogenicity Infects surgical wounds, produces the toxin responsible for toxic shock syndrome Sx = high fever, vomiting Produces an enterotoxin (acts on GI tract) that causes vomiting, nausea when ingested – one of the most common causes of food poisoning
- 30. Non spore forming Firmicutes Listeria Listeria monocytogenes – contaminate of food esp. dairy products Survives within phagocytic cells Grows at refrigerator temps If infects pg women – child stillborn or serious damage to fetus
- 31. Non spore forming Firmicutes Streptococcus – G + cocci , forms chains Beta hemolytic streptococci – when grown on blood agar forms a clear zone of hemolysis Streptococcus pyogenes = beta hemolytic, group A streptococci Group A represents one of an antigenic group A – G Scarlet fever, pharyngitis (sore throat), erysipelas, impetigo, rheumatic fever Virulence factor is M protein on bacterial surface wh/ allows bacteria to avoid phagocytosis
- 32. Streptococcus Streptococcus agalactiae – beta hemolytic group B – neonatal sepsis Non-beta hemolytic streptococci Are alpha hemolytic with green zones around colonies that represent partial destruction of the RBCs Streptococcus pneumoniae –pneumococcal pneumonia Streptococcus mutans – primary cause of tooth decay
- 33. Actinobacteria – high GC species Mycobacterium – acid fast, aerobic rods Have a waxy cell wall that makes it difficult for stains, nutrients, Abs to enter cell but makes them resistant to environmental stresses Pathogens = M. tuberculosis – TB, M. leprae – leprosy (Hansen’s disease) Streptomyces, Actinomyces – filamentous bacteria that resemble molds Most commercial Abs are produced by Streptomyces They produce a gas called geosmin that gives soil its musty odor
- 34. Nonproteobacteria –G- bacteria Cyanobacteria – aerobic photosynthetic bacteria Blue green pigmentation Carry out O2 producing photosynthesis like eukaryotic plants and algae Many can fix Nitrogen from the atmosphere in specialized cells = heterocysts Unicellular, colonial, filamentous forms Played an important part in the development on life on Earth – originally little free O2 (1%)- now 21%
- 35. Nonproteobacteria –G- bacteria Spirochetes –move by axial or endoflagella located beneath the outer membrane of the CW, movement is corkscrew motion to move thru liquid Treponema pallidum – syphilis Borrelia – relapsing fever and Lyme’s disease Leptospira sp. leptospirosis
- 36. Spirochetes Spirochetes are Gram-negative helical bacteria that use Axial Filaments, a kind of flagellum (and a.k.a., endoflagella), to display motility. Axial filaments and their spiral shape allow motility within highly viscous environments, such as mud and mucous.
- 37. Genus Treponema & Borrelia These bacteria are spirochetes: Borrelia burgdorferi causes Lyme disease. Treponema pallidum causes Syphilis.
- 38. Domain Archaea – cell walls lack peptidoglycan Extreme halophiles – live in high salt environments ex. Great Salt Lake, Utah Ex. Halobacterium, Halococcus Methanogens – obligate anaerobes Produce methane from CO2 and H2 Found in volcanic rock, marshes, lake bottoms, animal feces Part of microbiota of human colon, vagina , mouth Methanobacterium used to convert sludge into methane in sewage tx
- 39. Domain Archaea Thermoacidophiles live under extremely acidic and extremely hot conditions Ex. Sulfolobus acidocaldarius grows well at temps of 85 degrees C and in soil with a pH of 1.0