1. Foundations in Microbiology Seventh Edition
Lecture PowerPoint to accompany
Foundations in Microbiology Seventh Edition
Talaro
Chapter 19
The Gram-Positive Bacilli of Medical Importance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

2. 19.1 Medically Important Gram-Positive Bacilli
Can be subdivided into three general groups, based on presence or absence of endospores and acid-fastness
Three general groups:
Endospore-formers
Non-endospore-formers
Irregular shaped and staining properties 2 2

3. 3 3

4. 19.2 Spore-Forming Bacilli
Genus Bacillus
Genus Clostridium
Genus Sporolactobacillus 4 4

5. General Characteristics of the Genus Bacillus
Gram-positive, endospore-forming, motile rods
Mostly saprobic
Aerobic and catalase positive
Versatile in degrading complex macromolecules
Source of antibiotics
Primary habitat is soil
2 species of medical importance:
Bacillus anthracis
Bacillus cereus 5 5

6. Bacillus Anthracis Large, block-shaped rods
Central spores that develop under all conditions except in the living body
Virulence factors – polypeptide capsule and exotoxins
3 types of anthrax:
Cutaneous – spores enter through skin, black sore- eschar; least dangerous
Pulmonary –inhalation of spores
Gastrointestinal – ingested spores 6 6

7. Figure 19.2 Cutaneous anthrax7 7

8. Control and Treatment
Treated with penicillin, tetracycline, or ciprofloxacin
Vaccines
Live spores and toxoid to protect livestock
Purified toxoid; for high risk occupations and military personnel; toxoid 6 inoculations over 1.5 years; annual boosters 8 8

9. Figure 19.1 (a) Bacillus anthracis

10. Foundations in Microbiology Seventh Edition
Lecture PowerPoint to accompany
Foundations in Microbiology Seventh Edition
Talaro
Chapter 20
The Gram-Negative Bacilli of Medical Importance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10

11. 20.1 Aerobic Gram-Negative Nonenteric Bacilli
Large, diverse group of non-spore-forming bacteria
Wide range of habitats – large intestines (enteric), zoonotic, respiratory, soil, water
Most are not medically important; some are true pathogens, some are opportunists
All have a lipopolysaccharide outer membrane of cell wall – endotoxin 11 11

12. 12 12

13. 20.4 Coliform Organisms and Diseases13 13

14. Escherichia Coli: The Most Prevalent Enteric Bacillus
Most common aerobic and non-fastidious bacterium in gut
150 strains
Some have developed virulence through plasmid transfer, others are opportunists 14 14

15. Pathogenic Strains of E. Coli
Enterotoxigenic E. coli causes severe diarrhea due to heat-labile toxin and heat-stable toxin – stimulate secretion and fluid loss; also has fimbriae
Enteroinvasive E. coli causes inflammatory disease of the large intestine
Enteropathogenic E. coli linked to wasting form infantile diarrhea
Enterohemorrhagic E. coli, O157:H7 strain, causes hemorrhagic syndrome and kidney damage 15 15

16. Escherichia coli
Pathogenic strains frequent agents of infantile diarrhea – greatest cause of mortality among babies
Causes ~70% of traveler’s diarrhea
Causes 50-80% UTI
Coliform count – indicator of fecal contamination in water 16 16

17. Figure 20.14 Rapid identification of E. coli O157:H717 17

18. Other Coliforms Clinically important mainly as opportunists
Klebsiella pneumoniae – normal inhabitant of respiratory tract, has large capsule, cause of nosocomial pneumonia, meningitis, bacteremia, wound infections, and UTIs
Enterobacter sp. – UTIs, surgical wounds
Citrobacter sp. – opportunistic UTIs and bacteremia
Serratia marcescens – produces a red pigment; causes pneumonia, burn and wound infections, septicemia and meningitis 18 18

19. Foundations in Microbiology Seventh Edition
Lecture PowerPoint to accompany
Foundations in Microbiology Seventh Edition
Talaro
Chapter 21
Miscellaneous Bacterial Agents of Disease
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

20. 21.2 Curviform Gram-Negative Bacteria and Enteric Diseases
Three genera:
Vibrio – comma-shaped rods, single polar flagellum
Campylobacter – short spirals or curved rods; one flagellum
Helicobacter – spirochete with tight spirals and several polar flagella

21. Vibrio Cholera Comma-shaped, possess unique O and H Ags
El Tor biotype: survives longer, more infectious
Infectious dose 108
Infects mucous barrier of small intestine, noninvasive
Cholera toxin causes electrolyte and water loss through secretory diarrhea, “rice water stool”; resulting dehydration leads to muscle, circulatory, and neurological symptoms
Treatment: oral rehydration, tetracycline
Vaccine available

22. Figure 21.14 (a-b) Alterations in intestinal function caused by cholera toxin

23. Figure 21.14 (c) Alterations in intestinal function caused by cholera toxin