Pathogenic mycobacteria
Mycobacteria possess a lipid-rich cell wall that retains some dyes, resisting decolourization with acid (hence they are known as acid-fast). There are more than 50 species; although most are environmental…
Diphtheria, tetanus and pertussis
These three organisms are from widely differing taxonomic groups but are linked by being important diseases of childhood that are mediated by toxins and can be prevented by childhood immunization…
Listeria, Bacillus, Corynebacterium and environmental mycobacteria
Listeria Listeria are important Gram-positive organisms that can grow at low temperatures (4–10 °C); Listeria monocytogenes is associated with human disease. Epidemiology Listeria spp. are found in soil or animal…
Streptococcus pneumoniae, other Gram-positive cocci and the alpha-haemolytic streptococci
Streptococcus pneumoniae Streptococcus pneumoniae (or pneumococcus) is a Gram-positive coccus seen in pairs, which is typically α-haemolytic, but can be variable. Pathogenesis Streptococcus pneumoniae has a polysaccharide capsule that protects…
Streptococcal infections
The main characteristics of streptococci include the following. They are Gram-positive cocci arranged in pairs and chains. They are fastidious facultative anaerobes. They require rich blood-containing media. They may be…
2: Bacteriology
Staphylococci are part of the normal flora and important human pathogens. There are more than 26 species but only a few are pathogenic. Staphylococcus aureus is the most invasive species,…
Emerging infections
The incidence of an infection varies with changes in pathogen virulence and in the immunity of the host population. Many infectious diseases have a characteristic pattern. For example, meningococcal infection…
Infection in the hospital environment
Infection is a major cause of mortality and morbidity in patients admitted to hospital. The most frequent types of infection are urinary tract, respiratory, wound, skin and soft-tissue infections, and…
Principles of infection control
Identifying an Outbreak An outbreak, whether in a hospital or the community, must first be recognized by clinical awareness and effective laboratory diagnosis; data must be managed centrally, a process…
Sources and transmission of infection
Sources of Infection Infection is caused either by organisms from the host’s normal flora (endogenous infection) or by organisms transmitted from another source (exogenous infection). Endogenous Infection The normal flora…
