Basic laboratory procedures in clinical bacteriology

Preface viii Introduction 1 Quality assurance in bacteriology 2 Introduction 2 Definitions 2 Internal quality control 6 External quality assessment 16 PART I Bacteriological investigations 19 Blood 20 Introduction 20 When and where bacteraemia may occur 20 Blood collection 20 Blood-culture media 22 Processing of blood cultures 23 Cerebrospinal fluid 25 Introduction 25 Collection and transportation of specimens 25 Macroscopic inspection 26 Microscopic examination 26 Preliminary identification 28 Susceptibility testing 29 Urine 30 Introduction 30 Specimen collection 30 Culture and interpretation 32 Interpretation of quantitative urine culture results 34 Identification 35 Susceptibility tests 36 Stool 37 Introduction 37 Etiological agents and clinical features 37 Appropriate use of laboratory resources 39 Collection and transport of stool specimens 40 Visual examination of stool specimens 41 Enrichment and inoculation of stool specimens 41 Media for enteric pathogens 42 Primary isolation 42 Preliminary identification of isolates 44 v Final microbiological identification 50 Serological identification 54 Upper respiratory tract infections 60 Introduction 60 Normal flora of the pharynx 60 Bacterial agents of pharyngitis 61 Collection and dispatch of specimens 62 Direct microscopy 62 Culture and identification 63 Susceptibility testing 65 Lower respiratory tract infections 66 Introduction 66 The most common infections 66 Collection of sputum specimens 68 Processing of sputum in the laboratory (for non-tuberculous infections) 68 Culture for Mycobacterium tuberculosis 72 Interpretation of cultures for M. tuberculosis 74 General note on safety 74 Sexually transmitted diseases 76 Introduction 76 Urethritis in men 77 Genital specimens from women 79 Specimens from genital ulcers 82 Purulent exudates, wounds and abscesses 86 Introduction 86 Commonly encountered clinical conditions and the most frequent etiological agents 86 Collection and transportation of specimens 89 Macroscopic evaluation 90 Microscopic examination 91 Culture 92 Identification 93 Susceptibility testing 97 Anaerobic bacteriology 98 Introduction 98 Description of bacteria in relation to oxygen requirement 98 Bacteriology 98 Antimicrobial susceptibility testing 103 Introduction 103 General principles of antimicrobial susceptibility testing 103 Clinical definition of terms “resistant” and “susceptible”: the three category system 104 Indications for routine susceptibility tests 106 vi CONTENTS Choice of drugs for routine susceptibility tests in the clinical laboratory 107 The modified Kirby–Bauer method 109 Direct versus indirect susceptibility tests 117 Technical factors influencing the size of the zone in the disc-diffusion method 118 Quality control 120 Serological tests 122 Introduction 122 Quality control measures 122 Serological reactions 125 Serological tests for syphilis 126 Febrile agglutinins tests 133 Antistreptolysin O test 135 Bacterial antigen tests 137 PART II Essential media and reagents 141 Introduction 142 Pathogens, media and diagnostic reagents 143 Blood 144 Cerebrospinal fluid 144 Urine 145 Stool 146 Upper respiratory tract 147 Lower respiratory tract 148 Urogenital specimens for exclusion of sexually transmitted diseases 149 Pus and exudates 149 List of recommended media and diagnostic reagents for the intermediate microbiological laboratory 150 Selected further reading 154 Index 155 vii