Spiral bacteria
Leptospira There are two main species: Leptospira interrogans, which contains all of the pathogenic strains, and L. biflexa, a non-pathogen. L. interrogans has more than 200 serovariants that may be…
Environmental pathogens: Pseudomonas, Burkholderia and Legionella
Pseudomonas spp. Most Pseudomonas spp. are environmental organisms that can cause opportunistic infections in a healthcare environment. Pseudomonas Aeruginosa This organism is widespread in the environment, but rare in the…
Enterobacteriaceae clinical syndromes
Salmonella There are two Salmonella species that account for the majority of human and animal infections: S. enterica and S. bongori. Salmonellosis Salmonella are host-adapted to animals and humans. Infection…
Pathogenicity of enteric Gram-negative bacteria
The Enterobacteriaceae are a large family (>20 genera and 100 species) of facultatively anaerobic Gram-negative bacilli that are easily cultured, reduce nitrate and ferment glucose. The wide diversity of named…
Small Gram-negative coccobacilli: Haemophilus, Brucella, Francisella, Yersinia and Bartonella
Haemophilus Haemophilus spp. are fastidious Gram-negative coccobacilli that colonize mucosal surfaces. H. influenzae and H. ducreyi are the main pathogenic species. Haemophilus Influenzae Haemophilus influenzae expresses an antiphagocytic polysaccharide capsule…
Neisseria and Moraxella
Neisseria gonorrhoeae Infection with Neisseria gonorrhoeae, a Gram-negative diplococcus, is most common in individuals between 15 and 35 years of age. It is almost exclusively spread by sexual contact. Pathogenesis…
Non-sporing anaerobic infections
Non-sporing anaerobes form the major part of the normal human bacterial flora, outnumbering all other organisms in the gut by a factor of 103. They are also found in the…
Clostridium
Clostridium spp. are anaerobic spore-forming organisms that are able to survive well in the environment. Their normal habitats are soil, water and the intestinal tract of humans and animals. Only…
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…
