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

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

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

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

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

Figure 19.2 Cutaneous anthrax 7 7

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

Figure 19.1 (a) Bacillus anthracis

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

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

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20.4 Coliform Organisms and Diseases 13 13

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

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

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

Figure 20.14 Rapid identification of E. coli O157:H7 17 17

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

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.

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

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

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

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