Microbiology and Aging (eBook)

Microbiology and Aging 1
Title Page 2
Copyright Page 3
Preface 5
Contents 7
Contributors 9
Chapter 1 11
Ageing Theories, Diseases and Microorganisms 11
Biology of Ageing 11
Mechanistic Theories on Ageing 11
Programmed Theories of Ageing 12
Damage-Based Theories 13
Energy Consumption Hypothesis 14
Free Radical Theory 14
DNA-Damage Theory 15
Microorganisms and Ageing 16
Ageing and Disease/Infection 16
Increased Sensitivity of Infection in the Elderly 19
Does Infection Contribute to Ageing? 19
Conclusion 19
References 20
Chapter 2 24
Indigenous Microbiota and Association with the Host 24
Human Development, Microorganisms, and ‘Normal Flora’ 24
Indigenous Microbiota (Normal Flora) 25
Microbiota Differences in Children and Adults 26
The Development of the Indigenous Microbiota 26
Skin 27
Mouth 28
Upper Gastrointestinal Tract 30
Oseophagus 31
Stomach 31
Small Intestine 32
Colon 32
Microflora of the Infant’s Gut 33
Adult Indigenous Microbiota in the Colon 34
Respiratory Tract 35
UTI (Including Vagina) 38
Eyes 39
Central Nervous System 40
Adverse Effects of the ‘Normal’ Microbiota of the Host 41
Conclusion 42
References 42
Chapter 3 47
Infections in the Elderly 47
Introduction 47
Urinary Tract Infections 48
Pneumonia 50
Sepsis and Bacteremia 52
Skin and Soft-Tissue Infections 55
Cellulitis 55
Necrotizing Fasciitis 56
Onychomycosis 57
Herpes Zoster 58
What is the Consequence of an Older Society for Infectious Disease Research? 58
Concluding Remarks 59
References 60
Chapter 4 64
Skin Aging and Microbiology 64
Introduction 64
Factors and Theories Pertaining to Cutaneous Aging 64
Chemistry of Intrinsic Aging: Telomeres 65
Free Radicals 67
Estrogens 67
Chemistry of Extrinsic Aging 68
Characteristics of Aging Skin 69
Epidermis 69
Decreased Cell Turnover 70
Dermis 70
Collagen 71
Elastin 73
Glycosaminoglycans 73
Melanocytes 74
Vasculature 75
Subcutaneous Tissue 75
The Role of Free Radicals in Photoaging 75
Changes in Skin Appearance 76
Dry Skin 76
Benign Neoplasms in Aging Skin 76
Treatment of Photoaged Skin 76
Prevention 77
Some Notable Antioxidants 79
Sun Avoidance 82
Microbiology of the Skin 82
Microflora of the Skin 83
Skin Flora from Birth 84
Normal Adult Skin Flora 86
Bacterial Interactions, Skin Physiology, and Flora on the Skin 88
Skin Flora and Infection 89
Conclusion 90
References 91
Chapter 5 102
Lung Infections and Aging 102
Introduction 102
Age-Associated Changes in Lung Structure and Function 102
Lung Tissue 102
Chest Wall 103
Airway Protection 104
Mucociliary Clearance 104
Immunological Changes Associated with Advancing Age 105
Systemic Immunity 105
Innate Immunity 105
Neutrophils 106
Dendritic Cells 106
Macrophage 107
NK Cells 107
Adaptive Immunity 108
T Cells 108
B Cells 109
Pulmonary 109
Lung Infections in the Elderly 110
Community-Acquired Pneumonia 110
Viral Infection 111
Approach to Treatment and Prevention 112
Pneumonia 112
Antivirals 113
Vaccinations 113
Conclusion 114
References 114
Chapter 6 120
Influenza in the Elderly 120
Introduction 120
Virology and Epidemiology 120
Symptoms and Related Illnesses 122
Antivirals and Influenza Vaccines for the Elderly 123
Antiviral Treatment 124
Current Influenza Vaccines 125
Immune Responses in the Elderly 126
Innate Immune Responses 127
Adaptive Immunity 129
Influenza Vaccine Research and Future Prospects 129
Newer Methods of Inactivated Vaccine Production 129
Generating Broadly Cross-Reactive Responses 130
Live Attenuated Vaccines 131
Preclinical Vaccine Research and Development 131
Conclusion 132
References 133
Chapter 7 138
Changes in Oral Microflora and Host Defences with Advanced Age 138
Introduction 138
Overview of the Oral Environment 139
Changes in Oral Microflora with Age 140
Microflora in the Young 140
Microflora in the Elderly 141
Age-Related Direct and Indirect Effects on the Oral Microflora 142
Tooth Loss and Denture Wearing 142
Salivary Flow Rates 143
Oral Hygiene, Medication, and Systemic Disease 145
Dietary Habits and Malnutrition 146
Host Defences in the Oral Cavity 147
Changes in Oral Host Defences with Age 149
Conclusion 151
References 152
Chapter 8 160
Influence of the Gut Microbiota with Ageing 160
Introduction 160
Activities of the Gut Microbiota 161
Nutrition 161
Metabolism 164
Immune System 166
Influence of Ageing 167
Microbiota of the Infant 167
Microbiota of the Elderly 171
Concluding Remarks 174
References 175
Chapter 9 181
A Gut Reaction: Aging Affects Gut-Associated Immunity 181
Introduction 181
Architecture of Intestine and Distribution of GALT 182
Intestinal Microbiota 184
Oral Tolerance 190
Mechanisms of Innate Intestinal Immunity 195
Toll-Like Receptors 195
Microbicidal Peptides and Proteins 198
Crypts and Stem Cells 200
Adaptive Intestinal Immunity 201
Antimicrobial Actions of IgA 201
Intraepithelial Lymphocytes 203
Intestinal B Lymphocytes 205
Effects of Aging on the GALT 207
Aging of the Intestinal Epithelium 207
Enterocytes 207
Toll-Like Receptor 208
Intraepithelial Lymphocytes 209
GALT B cells and GC 210
Homing of Cells to GALT and Associated Lymphoid Tissue 214
Exploring Examples of GALT Aging 216
Manning the Barrier: Aging and the Intestinal Epithelium 216
Peering into the Crypt: An Aging Effect in Want of an Explanation 217
References 219
Chapter 10 229
Clostridium and The Ageing Gut 229
Introduction 229
Intestinal Flora and Disease 229
Antibiotic-Associated Diarrhoea, Differential Diagnosis, and Spectrum of Disease 230
Aetiology of Infectious AAD 231
Staphylococcus aureus 233
Salmonella spp 233
Candida spp 234
Other Organisms 234
Clostridium Difficile 235
Microbiological History 235
Natural History 236
Asymtomatic Human Carriage 236
Infants 236
Adults 237
Pathogenicity 237
Adherence 238
Capsules 238
Enzymes 239
Toxins 239
Clinical Aspects of C. difficile Infection 241
Antibiotic-Associated Diarrhoea 242
Antibiotic-Associated C. difficile Colitis 242
Antibiotic-Associated C. difficile Pseudomembranous Colitis 242
Fulminant Colitis 242
Other CDAD Associations 243
Clinical History and Risk Factors 243
Age-Related Susceptibility 243
Antibiotic-Associated Usage 244
Chemotherapy and Neoplastic Agents 245
Immunosupression and Other Causes 246
The Frequency of C. difficile-Associated Diarrhoea 247
Community 247
Nosocomial 247
Clostridium perfringens 248
Microbiological History 248
Natural History 249
Asymptomatic Human Carriage 250
Pathogenicity 251
Adhesion 251
Capsules 251
Enzymes 252
Toxins 252
C. Perfringens Enterotoxin-Associated Disease 254
Antibiotic-Associated CPEnt Diarrhoea 255
Antibiotic-Associated CPEnt Colitis 255
Other CPEnt Associations 255
Clinical History and Risk Factors 255
Antibiotics 255
Age-Related Susceptibility 256
Immunosupression 256
Others 256
The Frequency of C. Perfringens-Associated Diarrhoea 256
Community 257
Nosocomial 257
Conclusion 258
References 259
Chapter 11 269
The Significance of Helicobacter Pylori Acquisition and the Hygiene Hypothesis 269
Introduction 269
Medical Significance 270
Pathogenicity/Virulence 271
Transmission and Epidemiology of H. Pylori 272
Age and Acquisition of H. Pylori 274
The Hygiene Hypothesis Theory 275
Conclusion 276
References 277
Chapter 12 281
Probiotics and the Ageing Gut 281
Introduction 281
History of Probiotics 282
Gut Physiology 282
Therapeutic Effects of Probiotics 283
Probiotic Effects in Neonates and Children 283
Probiotic Effects in Adults and Children 284
Lactose Intolerance 284
Helicobacter Pylori Infection 285
Small-Bowel Bacterial Overgrowth 286
Viral Diarrhoea 286
Acute Gastroenteritis 286
Bacterial Diarrhoea 287
Antibiotic-associated and C. difficile-induced Diarrhoea 288
Constipation 289
Irritable Bowel Syndrome and Inflammatory Bowel Disease 289
Other Areas 290
Ongoing Research into Probiotics 290
Conclusion 292
References 292
Chapter 13 296
Microbiological Theory of Autism in Childhood 296
Introduction 296
Current Theories on Autism 298
Genetic Predisposition 298
Serotonin and Catecholamines 298
Serotonin 298
Catecholamines 299
Microbiological Link 299
Changes in the GI Tract 300
Sulphation Deficit 300
Peptides 301
Autistic Enterocolitis 301
Microbiological Link 301
Autoimmunity 303
The Autoimmunity Theory of Autism 303
Microbiological Link 303
Vaccination 304
Microbiological Link 304
Gamma-Aminobutyric Acid 305
The Blood–Brain Barrier 305
Microbiology Link 306
Fatty Acid Metabolism 306
Microbiological Link 307
In Utero Factors 307
Microbiological Link 308
Neurotransmission and Bacteria 308
Conclusions 308
References 310
Chapter 14 317
Decomposition of Human Remains 317
Introduction 317
Post Mortem Hypostasis (Lividity, Livor Mortis) 318
Rigor Mortis 318
Cooling (Algor Mortis) 319
Cadaveric Decay 320
Intrinsic Microorganisms and the Chemistry of Death 321
Protein Decomposition (Proteolysis) 322
Decomposition of Fat 323
Decomposition of Carbohydrates 324
Decomposition of Bone 325
Extrinsic Organisms Involved in Human Decomposition 326
Environmental Controls that Promote and Inhibit Putrefactive Decay 328
Temperature 329
Moisture 330
Contrasting Depositional Environments (Soil Burial vs. Surface Exposure) 330
First Day (Fresh) 330
First Week (Fresh to Bloated) 330
First Month (Bloated to Decay) 331
The First Year (Dry) 331
First Decade (Bone Breakdown) 331
The Microclimate Associated with Human Decomposition 331
Differential Decomposition 332
Conclusion 334
References 334
Index 339