The laboratory investigation of infection
Specimens Any tissue or body fluid can be subjected to microbiological investigation with the aim of identifying the infecting pathogen and predicting response to therapy. To optimize the diagnostic benefit…
Resistance to antibacterial agents
Resistance occurs when a previously susceptible organism is no longer inhibited by an antibiotic at a concentration that can be safely achieved in clinical practice. Resistance can develop quickly because:…
Pathogenicity and pathogenesis of infectious disease
Definitions Humans encounter bacteria, viruses and parasites that do not cause disease. An infection occurs when microorganisms cause ill-health. Term Definition Pathogen An organism capable of causing disease Commensal An…
1: Concepts
Bacterial classification is important, revealing the identity of an organism so that its behaviour and likely response to treatment can be predicted. Bacterial Structural Components Bacterial cell walls are rigid…
Innate immunity and normal flora
The innate immune system, which consists of the normal flora, physical barriers such as the skin, antibacterial proteins and phagocytic cells, is an important defence mechanism against infection. Many responses…
Antibiotics in clinical use
Beta-Lactam Antibiotics Penicillins work by inhibiting peptidoglycan cross-linkage. Modifications to the penicillins have extended their antibacterial spectrum and improved absorption. Penicillins now include: natural penicillins (e.g. benzylpenicillin, penicillin V); penicillinase-resistant…
Antibacterial therapy
Principles of Antibiotic Therapy Antibiotics aim to kill organisms while causing no harm to the patient – this concept is known as selective toxicity. It is best achieved by inhibiting…
