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Bacterial structure and functions
Streptococcus pyogenes (Group A Strep)
Streptococcus agalactiae (Group B Strep)
Clostridium botulinum (Botulism)
Clostridium difficile (Pseudomembranous colitis)
Clostridium tetani (Tetanus)
Bacillus cereus (Food poisoning)
Corynebacterium diphtheriae (Diphtheria)
Bacillus anthracis (Anthrax)
Salmonella typhi (typhoid fever)
Legionella pneumophila (Legionnaires disease and Pontiac fever)
Yersinia pestis (Plague)
Vibrio cholerae (Cholera)
Francisella tularensis (Tularemia)
Bordetella pertussis (Pertussis/Whooping cough)
Haemophilus ducreyi (Chancroid)
Mycobacterium tuberculosis (Tuberculosis)
Mycobacterium avium complex (NORD)
Borrelia burgdorferi (Lyme disease)
Borrelia species (Relapsing fever)
Treponema pallidum (Syphilis)
Rickettsia rickettsii (Rocky Mountain spotted fever) and other Rickettsia species
Coxiella burnetii (Q fever)
Ehrlichia and Anaplasma
Gardnerella vaginalis (Bacterial vaginosis)
Haemophilus ducreyi (Chancroid)
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sexual transmission p. 180
Ursula Florjanczyk, MScBMC
Alexandru Duhaniuc, MD
Haemophilus ducreyi is a Gram-negative coccobacillus, which means that shape-wise, it’s somewhere between a spherical coccus and a rod-like bacillus.
Haemophilus ducreyi is an obligate human pathogen and causes a sexually transmitted disease, called chancroid.
Now, Haemophilus ducreyi has a thin peptidoglycan layer, so it doesn’t retain the crystal violet dye used during Gram staining.
Instead, like any other Gram-negative bacteria, it stains pink with safranin dye.
So, under the microscope, the bacteria look like short or relatively long pink rods with rounded ends, that usually grow in chains, so they’re sometimes compared to a “school of fish”.
Now, Haemophilus ducreyi is: non-motile, so it doesn’t move / facultatively anaerobic, which means it can survive in both aerobic and anaerobic environments / oxidase positive which means it produces an enzyme called oxidase / and catalase negative, which means it doesn’t produce an enzyme called catalase.
Finally, Haemophilus ducreyi can be cultivated on chocolate agar, because this medium contains essential nutrients that Haemophilus ducreyi need to grow, like factor X, also called hemin.
They’re fastidious bacteria that only grow in a CO2 environment, at a temperature between 33 and 35 degrees Celsius, and it forms small, grey or translucent colonies.
Now, Haemophilus ducreyi enters the body through mucosal and skin breaks and has a number of virulence factors, that are like assault weaponry that help it attack and destroy the host cells, and evade the immune system.
Now, Haemophilus ducreyi is encapsulated, so it has a polysaccharide layer called a capsule, that acts like a shield, protecting the bacteria against phagocytic cells like macrophages and neutrophils.
On the capsule there are fimbria-like proteins, such as Flp1, Flp2 and Flp3 and uses them to attach to subcutaneous epithelial cells and fibroblasts.
Haemophilus ducreyi (Chancroid) is a gram-negative, facultatively anaerobic, nonmotile coccobacillus. It is known to cause a sexually transmitted disease called chancroid, which is characterized by one or more painful genital ulcers associated with tender inguinal adenopathy.
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