Chapter 11

1. Chapter 11 Characterizing and Classifying Prokaryotes

2. General Characteristics of Prokaryotic Organisms Prokaryotes Most diverse group of cellular microbes Habitats From Antarctic glaciers to thermal hot springs From colons of animals to cytoplasm of other prokaryotes From distilled water to supersaturated brine From disinfectant solutions to basalt rocks Only a few capable of colonizing humans and causing disease MDufilho

3. Coccus Figure 11.1 Typical prokaryotic morphologies Spirillum Coccobacillus Spirochete Bacillus Pleomorphic Vibrio MDufilho

4. General Characteristics of Prokaryotic Organisms Reproduction of Prokaryotic Cells All reproduce asexually Three main methods Binary fission (most common) Snapping division Budding MDufilho

5. Cell replicates its DNA. Cell wall Cytoplasmicmembrane Nucleoid ReplicatedDNA The cytoplasmicmembrane elongates,separating DNAmolecules. Figure 11.2 Binary fission Cross wall forms;membraneinvaginates. Cross wall formscompletely. Daughter cellsmay separate. MDufilho

6. Figure 11.3 Snapping division-overview MDufilho

7. Spores Figure 11.4 Actinomycetes spores MDufilho

8. DNA is replicated One daughter DNAmolecule is movedinto bud Figure 11.5 Budding Young bud Daughter cell MDufilho

9. Modern Prokaryotic Classification Currently based on genetic relatedness of rRNA sequences Three domains Archaea Bacteria Eukarya MDufilho

10. Survey of Bacteria Low G+C Gram-Positive Bacteria Clostridia Rod-shaped, obligate anaerobes, toxin producing, endospore formers Important in medicine and industry MDufilho

11. Bacterial Diseases of the Digestive System Bacterial Gastroenteritis: Antimicrobial-Associated Diarrhea Signs and symptoms Pseudomembranous colitis occurs in severe cases Pathogen and virulence factors Caused by Clostridium difficile Antimicrobial use facilitates overgrowth of C. difficile C. difficile produces two toxins Pathogenesis Toxins mediate inflammation and pseudomembrane formation MDufilho

12. Lesions Figure 23.9 Pseudomembranous colitis MDufilho

13. Bacterial Diseases of the Digestive System Bacterial Gastroenteritis: Antimicrobial-Associated Diarrhea Epidemiology By-product of modern medicine Any antimicrobial can trigger the disease Diagnosis, treatment, and prevention Diagnosis based on presence of bacterial toxin in stool Treat with antimicrobials Avoid unnecessary use of antimicrobials MDufilho

14. Bacterial Diseases of the Skin and Wounds Gas Gangrene Signs and symptoms Blackening of infected muscle and skin Presence of gas bubbles Pathogens and virulence factors Caused by several Clostridium species Bacterial endospores survive harsh conditions Vegetative cells secrete 11 toxins MDufilho

15. Bacterial Diseases of the Skin and Wounds Gas Gangrene Pathogenesis and epidemiology Traumatic event must introduce endospores into dead tissue Mortality rate exceeds 40% Diagnosis, treatment, and prevention Appearance is usually diagnostic Rapid treatment is crucial Surgical removal of dead tissue Administration of antitoxin and penicillin Prevent with proper cleaning of wounds MDufilho

16. Survey of Bacteria Low G+C Gram-Positive Bacteria Low G+C bacilli and cocci Bacillus–many common in soil – B. anthracis –cause of cutaneous and pulmonary anthrax Listeria–contaminates milk and meat products– Listeria monocytogenes Causes meningitis of immuno-compromised – pregnant, newborns, elderly Organism can live within cells undetected by the immune system MDufilho

17. Bacterial Diseases of the Skin and Wounds Cutaneous Anthrax Caused by Bacillus anthracis Characterized by an eschar Black, painless, ulcer Treated with antimicrobial drugs Prevention requires control of the disease in animals MDufilho

18. Survey of Bacteria Low G+C Gram-Positive Bacteria Low G+C bacilli and cocci Lactobacillus–grows in the body but rarely causes disease Streptococcus and Enterococcus–cause numerous diseases MDufilho

19. Bacterial Diseases of the Upper Respiratory System, Sinuses, and Ears Streptococcal Respiratory Diseases Signs and symptoms Sore throat and difficulty swallowing May progress to scarlet or rheumatic fever Pathogen and virulence factors Caused by group A streptococci (S. pyogenes) Variety of virulence factors M proteins, hyaluronic acid capsule, streptokinases, C5a peptidase, pyrogenic toxins, streptolysins MDufilho

20. Pus pockets on tonsils Streptococcal Pharyngitis (Strep Throat): pus pockets on tonsils The reddened appearance and pus pockets of a throat withpharyngitis

21. Bacterial Diseases of the Upper Respiratory System, Sinuses, and Ears Streptococcal Respiratory Diseases Pathogenesis Occurs when normal microbiota are depleted, large inoculum is introduced, or adaptive immunity is impaired Epidemiology Spread via respiratory droplets Occurs most often in winter and spring Diagnosis, treatment, and prevention Often confused with viral pharyngitis Penicillin is an effective treatment MDufilho

22. Bacterial Diseases of the Skin and Wounds Necrotizing Fasciitis Pathogen and virulence factors Most cases caused by S. pyogenes Various enzymes facilitate invasion of tissues Exotoxin A and streptolysin S are also secreted Pathogenesis and epidemiology S. pyogenes enters through breaks in the skin Usually spread person-to-person Diagnosis, treatment, and prevention Early diagnosis is difficult because symptoms are nonspecific Treat with clindamycin and penicillin MDufilho

23. Figure 19.6 Necrotizing fasciitis MDufilho

24. Survey of Bacteria Low G+C Gram-Positive Bacteria Low G+C bacilli and cocci Staphylococcus–one of the most common inhabitants of humans – S. aureus Can cause food poisoning – produces 5 toxins Endocarditis, styes, pneumonia, skin infections MDufilho

25. Bacterial Diseases of the Skin and Wounds Staphylococcal Scalded Skin Syndrome Pathogen and virulence factors Some Staphylococcus aureus strains One or two different exfoliative toxins cause SSSS Pathogenesis No scarring because dermis is unaffected Death is rare but may be due to secondary infections Epidemiology Disease occurs primarily in infants Transmitted by person-to-person spread of bacteria MDufilho

26. Figure 19.3 Staphylococcal scalded skin syndrome MDufilho

27. Bacterial Diseases of the Skin and Wounds Staphylococcal Scalded Skin Syndrome Diagnosis, treatment, and prevention Diagnosed by characteristic sloughing of skin Treated by administration of antimicrobial drugs Widespread presence of S. aureus makes prevention difficult MDufilho

28. Bacterial Diseases of the Skin and Wounds Impetigo (Pyoderma) and Erysipelas Pathogens and virulence factors Most cases are caused by S. aureus Some cases are caused by Streptococcus pyogenes Gram-positive coccus, arranged in chains Virulence factors similar to those of S. aureus M protein Hyaluronic acid Pyrogenic toxins MDufilho

29. Figure 19.4 Impetigo MDufilho

30. Figure 19.5 Erysipelas MDufilho

31. Bacterial Diseases of the Skin and Wounds Impetigo (Pyoderma) and Erysipelas Pathogenesis The bacteria invade where the skin is compromised Epidemiology Transmitted by person-to-person contact or via fomites Impetigo occurs most in children Erysipelas can also occur in the elderly MDufilho

32. Bacterial Diseases of the Skin and Wounds Impetigo (Pyoderma) and Erysipelas Diagnosis, treatment, and prevention The presence of vesicles is diagnostic for impetigo Treat with penicillin and careful cleaning of infected areas Prevent with proper hygiene and cleanliness MDufilho

33. Survey of Bacteria High G+C Gram-Positive Bacteria Mycobacterium Aerobic rods that sometimes form filaments Slow growth partly due to mycolic acid in its cell walls Mycobacterium tuberculosis - tuberculosis Actinomycetes Form branching filaments resembling fungi Important genera include Actinomyces, Nocardia, Streptomyces MDufilho

34. Survey of Bacteria Gram-Negative Proteobacteria Largest and most diverse group of bacteria Many have extensions called prosthecae Used for attachment and to increase surface area for nutrient absorption Alphaproteobacteria Pathogenic alphaproteobacteria Rickettsia Brucella MDufilho

35. Bacterial Diseases of the Skin and Wounds Rocky Mountain Spotted Fever Signs and symptoms Non-itchy spotted rash on trunk and appendages Pathogen and virulence factors Caused by Rickettsia rickettsii Pathogen avoids digestion in phagosome Pathogenesis Disease follows damage to blood vessels MDufilho

36. Disease at a Glance 19.2 Rocky Mountain Spotted Fever-overview

37. Bacterial Diseases of the Skin and Wounds Rocky Mountain Spotted Fever Epidemiology Transmitted via bite of infected tick Diagnosis, treatment, and prevention Diagnosed with serological testing Treated with various antimicrobials Prevented with the use of tick repellents and avoidance of tick-infested areas MDufilho

38. 3 6 27 1 26 2 19 48 5 31 31 8 218 14 58 42 6 53 314 228 119 17 167 265 52 116 27 Figure 19.9 Number of cases of Rocky Mountain spotted fever in the U.S., 1999-2009 25 17 48 780 650 24 1711 32 4382 1496 853 69 871 31 563 189 541 589 34 231 164 0 0–200 0 201–400 401–600 601–800 801–1000 MDufilho 1000

39. Survey of Bacteria Gram-Negative Proteobacteria Betaproteobacteria Pathogenic betaproteobacteria Neisseria Bordetella Burkholderia MDufilho

40. Bacterial STDs Gonorrhea – 2-5 days Signs and symptoms Men experience painful urination and a purulent discharge Women are often asymptomatic Pelvic inflammatory disease my develop Pathogen and virulence factors Caused by Neisseria gonorrhoeae Virulence factors include fimbriae, capsule, and endotoxin MDufilho

41. Bacterial STDs Gonorrhea Pathogenesis Bacteria attach to epithelial cells of the mucous membranes Epidemiology Gonorrhea occurs only in humans Risk increases with frequency of sexual encounters Diagnosis, treatment, and prevention Genetic probes used to diagnose asymptomatic infection Treat with broad-spectrum cephalosporins Prevent with safe sex practices MDufilho

42. Figure 24.5 Incidence of civilian gonorrhea in the U.S.-overview MDufilho

43. Survey of Bacteria Gram-Negative Proteobacteria Gammaproteobacteria Purple sulfur bacteria Intracellular pathogens Legionella Coxiella Methane oxidizers Glycolytic facultative anaerobes Family Enterobacteriaceae Pseudomonads Pseudomonas Azotobacter Azomonas MDufilho

44. Bacterial Diseases of the Skin and Wounds Pseudomonas Infection Pathogen and virulence factors Pseudomonas aeruginosa is the causative agent Found in soil, decaying matter, moist environments Virulence factors Adhesins, toxins, and a polysaccharide capsule Pathogenesis Infection can occur in burn victims Bacteria grow under the surface of the burn The bacteria kills cells, destroys tissue, and triggers shock MDufilho

45. Figure 19.8 Pseudomonas aeruginosa infection MDufilho

46. Survey of Bacteria Gram-Negative Proteobacteria No human pathogens Desulfovibrio – sulfate reducer Bdellovibrio – pathogen of Gram neg. bacteria Myxobacteria - MDufilho

47. Survey of Bacteria Gram-Negative Proteobacteria Epsilonproteobacteria Campylobacter Helicobacter – cause of peptic ulcers MDufilho

48. Survey of Bacteria Other Gram-Negative Bacteria Chlamydias Chlamydia Spirochetes Treponema Borrelia Bacteroids Bacteroides Cytophaga MDufilho

49. Bacterial STDs Syphilis Signs and symptoms Four phases of syphilis Primary syphilis Secondary syphilis Latent syphilis Tertiary syphilis MDufilho

50. Figure 24.6 The later lesions of syphilis-overview MDufilho