Haemophilus ducreyi | |
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Photomicrograph of H. ducreyi | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Gammaproteobacteria |
Order: | Pasteurellales |
Family: | Pasteurellaceae |
Genus: | Haemophilus |
Species: | H. ducreyi |
Binomial name | |
Haemophilus ducreyi | |
Haemophilus ducreyi are fastidious gram-negative coccobacilli bacteria. [1]
This species causes the sexually transmitted disease chancroid, a major cause of genital ulceration in developing countries characterized by painful sores on the genitalia. [2] 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. [1] Chancroid starts as an erythematous papular lesion that breaks down into a painful bleeding ulcer with a necrotic base and ragged edge. It has also been found to cause chronic skin ulceration away from the genitalia, infect children and adults, and behave in a manner that mimics yaws. [3]
H. ducreyi can be cultured on chocolate agar [4] and incubated in an environment with elevated humidity and CO2 enrichment at 33° to 35 °C. [5] It is best treated with a macrolide, e.g. azithromycin, and a third-generation cephalosporin, e.g. ceftriaxone.
Haemophilus ducreyi is a Gram-negative coccobacillus, and has a shape between a spherical coccus [6] and a rod-shaped bacterium. [1] This species of bacterium has pili, fine and tangled appendages composed predominantly of protein, that allow bacteria to attach to surfaces, including those of cells. [7]
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. [1]
Haemophilus ducreyi has been shown to have high phosphatase activity (acid phosphatase, alkaline phosphatase, and phosphoamidase). [1] There are specific temperature and nutritional necessities for the pathogen to grow, requiring advanced laboratory equipment to study the bacteria. [8] A saturated atmosphere with elevated CO2 levels is considered optimal for most strains, and the most favorable growth has been observed to occur under micro-aerophilic conditions achieved in a sealed anaerobic jar without a catalyst, using two envelopes that generate CO2 and H2, commonly referred to as Campylobacter growth conditions. [1]
Haemophilus ducreyi is a human pathogen; and there are no known animal or environmental reservoirs. [8] H. ducreyi is an opportunistic microorganism that infects its host by way of breaks in the skin or epidermis. Inflammation then takes place as the area of infection is inundated with lymphocytes, macrophages, and granulocytes. This pyogenic inflammation causes regional lymphadenitis in the sexually transmitted disease chancroid. [9]
Haemophilus ducreyi is able to defend itself against the immune response's T cells through two toxins: a hemolysin and the cytolethal distending toxin (CDT). 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. [10] Together, these toxins showcase the adeptness of H. ducreyi in manipulating host cell processes.
Although antigen detection, serology, and genetic amplification methods are sometimes used to diagnose infections with H. ducreyi and the genetic tests have greater sensitivity, they are not widely available, so cultures are currently considered the "gold standard" test, which has about 80% sensitivity under optimal combination of media. [11]
Single-dose antibiotic treatments using macrolides, third-generation cephalosporins, or fluoroquinolone continue to be effective in treating chancroid. [11] The first line treatments recommended by the U.S. Centers for Disease Control and Prevention are one of four options: azithromycin one gram orally in a single dose, ceftriaxone 250 mg intramuscularly in a single dose, ciprofloxacin 500 mg orally two times a day for three days, or erythromycin base 500 mg orally three times a day for seven days. [12] [13] 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. [1] Infected individuals are still susceptible to reinfection due to the absence of developed protective immunity. [11]
A rise in antimicrobial resistance among H. ducreyi strains result in a shift away from benzylpenicillin as the preferred treatment. [8]
Chlamydia, or more specifically a chlamydia infection, is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. Most people who are infected have no symptoms. When symptoms do appear they may occur only several weeks after infection; the incubation period between exposure and being able to infect others is thought to be on the order of two to six weeks. Symptoms in women may include vaginal discharge or burning with urination. Symptoms in men may include discharge from the penis, burning with urination, or pain and swelling of one or both testicles. The infection can spread to the upper genital tract in women, causing pelvic inflammatory disease, which may result in future infertility or ectopic pregnancy.
Mycoplasma genitalium is a sexually transmitted, small and pathogenic bacterium that lives on the mucous epithelial cells of the urinary and genital tracts in humans. Medical reports published in 2007 and 2015 state that Mgen is becoming increasingly common. Resistance to multiple antibiotics, including the macrolide azithromycin, which until recently was the most reliable treatment, is becoming prevalent. The bacterium was first isolated from the urogenital tract of humans in 1981, and was eventually identified as a new species of Mycoplasma in 1983. It can cause negative health effects in men and women. It also increases the risk for HIV spread with higher occurrences in those previously treated with the azithromycin antibiotics.
Urethritis is the inflammation of the urethra. The most common symptoms include painful or difficult urination and urethral discharge. It is a commonly treatable condition usually caused by infection with bacteria. This bacterial infection is often sexually transmitted, but not in every instance; it can be idiopathic, for example. Some incidence of urethritis can appear asymptomatic as well.
Neisseria gonorrhoeae, also known as gonococcus (singular) or gonococci (plural), is a species of Gram-negative diplococci bacteria isolated by Albert Neisser in 1879. It causes the sexually transmitted genitourinary infection gonorrhea as well as other forms of gonococcal disease including disseminated gonococcemia, septic arthritis, and gonococcal ophthalmia neonatorum.
Yaws is a tropical infection of the skin, bones, and joints caused by the spirochete bacterium Treponema pallidum pertenue. The disease begins with a round, hard swelling of the skin, 2 to 5 cm in diameter. The center may break open and form an ulcer. This initial skin lesion typically heals after 3–6 months. After weeks to years, joints and bones may become painful, fatigue may develop, and new skin lesions may appear. The skin of the palms of the hands and the soles of the feet may become thick and break open. The bones may become misshapen. After 5 years or more, large areas of skin may die, leaving scars.
Chancroid is a bacterial sexually transmitted infection characterized by painful sores on the genitalia. Chancroid is known to spread from one individual to another solely through sexual contact. However, there have been reports of accidental infection through the hand.
Haemophilus influenzae is a Gram-negative, non-motile, coccobacillary, facultatively anaerobic, capnophilic pathogenic bacterium of the family Pasteurellaceae. The bacteria are mesophilic and grow best at temperatures between 35 and 37 °C.
Neisseria meningitidis, often referred to as the meningococcus, is a Gram-negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. The bacterium is referred to as a coccus because it is round, and more specifically a diplococcus because of its tendency to form pairs.
Community-acquired pneumonia (CAP) refers to pneumonia contracted by a person outside of the healthcare system. In contrast, hospital-acquired pneumonia (HAP) is seen in patients who have recently visited a hospital or who live in long-term care facilities. CAP is common, affecting people of all ages, and its symptoms occur as a result of oxygen-absorbing areas of the lung (alveoli) filling with fluid. This inhibits lung function, causing dyspnea, fever, chest pains and cough.
A bubo is adenitis or inflammation of the lymph nodes and is an example of reactive infectious lymphadenopathy.
A genital ulcer is an open sore located on the genital area, which includes the vulva, penis, perianal region, or anus. Genital ulcers are most commonly caused by infectious agents. However, this is not always the case, as a genital ulcer may have noninfectious causes as well.
Gonorrhoea or gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. Infection may involve the genitals, mouth, or rectum. Infected males may experience pain or burning with urination, discharge from the penis, or testicular pain. Infected females may experience burning with urination, vaginal discharge, vaginal bleeding between periods, or pelvic pain. Complications in females include pelvic inflammatory disease and in males include inflammation of the epididymis. Many of those infected, however, have no symptoms. If untreated, gonorrhea can spread to joints or heart valves.
Kingella kingae is a species of Gram-negative facultative anaerobic β-hemolytic coccobacilli. First isolated in 1960 by Elizabeth O. King, it was not recognized as a significant cause of infection in young children until the 1990s, when culture techniques had improved enough for it to be recognized. It is best known as a cause of septic arthritis, osteomyelitis, spondylodiscitis, bacteraemia, and endocarditis, and less frequently lower respiratory tract infections and meningitis.
Gonococcemia is a rare complication of mucosal Neisseria gonorrhoeae infection, or Gonorrhea, that occurs when the bacteria invade the bloodstream. It is characterized by fever, tender hemorrhagic pustules on the extremities or the trunk, migratory polyarthritis, and tenosynovitis. It also rarely leads to endocarditis and meningitis. This condition occurs in 0.5-3% of individuals with gonorrhea, and it usually presents 2–3 weeks after acquiring the infection. Risk factors include female sex, sexual promiscuity, and infection with resistant strains of Neisseria gonorrhoeae. This condition is treated with cephalosporin and fluoroquinolone antibiotics.
Cytolethal distending toxins are a class of heterotrimeric toxins produced by certain gram-negative bacteria that display DNase activity. These toxins trigger G2/M cell cycle arrest in specific mammalian cell lines, leading to the enlarged or distended cells for which these toxins are named. Affected cells die by apoptosis.
In biology, a pathogen, in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
Neisseria gonorrhoeae, the bacterium that causes the sexually transmitted infection gonorrhea, has developed antibiotic resistance to many antibiotics. The bacteria was first identified in 1879.
Campylobacter coli is a Gram-negative, microaerophilic, non-endospore-forming, S-shaped bacterial species within genus Campylobacter. In humans, C. coli can cause campylobacteriosis, a diarrhoeal disease which is the most frequently reported foodborne illness in the European Union. C. coli grows slowly with an optimum temperature of 42 °C. When exposed to air for long periods, they become spherical or coccoid shaped.
Clostridioides difficile is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as C. difficile, or C. diff, and is a Gram-positive species of spore-forming bacteria. Clostridioides spp. are anaerobic, motile bacteria, ubiquitous in nature and especially prevalent in soil. Its vegetative cells are rod-shaped, pleomorphic, and occur in pairs or short chains. Under the microscope, they appear as long, irregular cells with a bulge at their terminal ends. Under Gram staining, C. difficile cells are Gram-positive and show optimum growth on blood agar at human body temperatures in the absence of oxygen. C. difficile is catalase- and superoxide dismutase-negative, and produces up to three types of toxins: enterotoxin A, cytotoxin B and Clostridioides difficile transferase. Under stress conditions, the bacteria produce spores that are able to tolerate extreme conditions that the active bacteria cannot tolerate.