User:Jlynn03/Haemophilus ducreyi

Pathogenesis Haemophilus ducreyi is a human pathogen; there are currently no known animals or environments where the pathogen is found to cause genital ulcer disease. However, there has been Haemophilus ducreyi bacteria found in rabbit blood culture specimen. - insert picture of photomicrograph

Structure Haemophilus ducreyi is a gram-negative bacteria. A study observing 12 strains of Haemophilus ducreyi found pilli in 10 of the strains using transmission electron microscopy. The pili has fine and tangled appendages, composed predominantly of protein, allowing bacteria to interact with and attach to surfaces, including a host cell.

Colonies - Colonies of Haemophilus ducreyi are described as yellow-grey, small, and semiopaque as well as nonmucoid. Scanning electron microscopy has been used to observe that the microbe can form a colony of many cells; the cells adhere to each other because of an intercellular matrix. This bond can make it difficult to isolate a single cell of Haemophilus ducreyi, hindering the genetic studies that have been done on the microbe.

Toxins Haemophilus ducreyi is able to defend against immune response T cells through two different toxins: hemolysin and cytolethal distending toxin (CDT). Hemolysin is a substance that is capable of lysing red blood cells. CDT is characterized by its ability to arrest epithelial cells in the G2 phase of the cell cycle and combats T cells by inducing apoptosis. These toxins manipulate host cell processes by counteracting the host immune response, particularly targeting T cells.

Suggested: Metabolism and Genetics section:

The genome of the human passaged H. ducreyi (35000HP) contains one 1.7-Mb chromosome displaying 1,693 open reading frames or ORFs.

Metabolism There is very limited research on the metabolic pathways of Haemophilus ducreyi; however, it has been shown that they have high phosphatase activity (acid phosphatase, alkaline phosphatase, and phosphoamidase). There are specific temperature and nutritional necessities for the pathogen to grow, requiring advanced laboratory equipment to study the pathogen.

Disease Haemophilus ducreyi is a causative agent of chancroid. (citation added) The first study linking this disease with the agent Hemophilus ducreyi was published in 1889 by Auguste Ducrey. Each year in the United States, there are over 2,000 cases of chancroid. (add to background)

Diagnosis

Techniques that can provide insights into H. ducreyi infections include:


 * 1) Antigen Detection to identify specific antigens produced by H. ducreyi and diagnose infections quicker than culture-based methods.
 * 2) Serology to detect antibodies produced by the host in response to H. ducreyi infection, providing evidence of exposure to the bacteirum.
 * 3) Genetic Amplification Methods like Polymerase Chain Reaction (PCR) to target the genetic material of H. ducreyi.
 * 4) Microscopy to reveal characteristic features of H. ducreyi, aiding in rapid diagnosis.
 * 5) Syndromic Management based on clinical presentation of genital ulcers is often employed.

Treatments

Single-dose antibiotic treatments using macrolides, third-generation cephalosporins, or fluoroquinolone continue to be effective in treating chancroid. Azithromycin 1 gm orally in a single dose, or Ceftriaxone 250 mg IM in a single dose, or Ciprofloxacin 500 mg orally 2 times/day for 3 days, or Erythromycin base 500 mg orally 3 times/day for 7 days. It should be noted that infected individuals are still susceptible to reinfection due to the absence of developed protective immunity.

Some antibodies were specific to all strains, while others targeted only certain groups of strains H. ducreyi, indicating that the outer membrane proteins of H. ducreyi can vary in their immune recognition. Infected individuals are still susceptible to reinfection due to the absence of developed protective immunity.

A rise in antimicrobial resistance among H. ducreyi strains result in a shift away from benzylpenicillin as the preferred treatment.

Images to add - difficulty finding Haemophilus ducreyi images open to modify and use commercially