10. chlamydia rickettsia and mycoplasma.pdf

Mycoplasmas ,Rickettsia and Chlamydia Wijini Wijayabandara (BSc. Biomedical Science; MSc. Molecular Life Sciences)  Mycoplasma Mycoplasmas are the smallest and simplest self-replicating bacteria The mycoplasma cell contains the minimum set of organelles essenti...

Mycoplasmas ,Rickettsia and Chlamydia Wijini Wijayabandara (BSc. Biomedical Science; MSc. Molecular Life Sciences)  Mycoplasma Mycoplasmas are the smallest and simplest self-replicating bacteria The mycoplasma cell contains the minimum set of organelles essential for growth and replication: plasma membrane, ribosomes, and a genome consisting of a double-stranded circular DNA molecule Unlike all other prokaryotes, the mycoplasmas have no cell walls, and they are consequently placed in a separate class called Mollicutes(mollis, soft; cutis, skin) Mycoplasmas are spherical to filamentous cells Without a cell wall, they are unaffected by many common antibiotics  The mycoplasmas presumably evolved by degenerative evolution from Gram-positive bacteria and are phylogenetically most closely related to some clostridia Mycoplasmas have been nicknamed the “crabgrass” of cell cultures because their infections are persistent, frequently difficult to detect and diagnose, and difficult to cure Several species are pathogenic in humans, including M. pneumoniae, a disease of the upper and lower respiratory tracts M. genitalium, which is believed to be involved in pelvic inflammatory diseases and Ureaplasma urealyticum infection causes nongonococcal urethritis in men Mycoplasma species are the ; smallest bacterial cells yet discovered Can survive without oxygen Fried-egg-shaped colonies are seen on agar A routine mycoplasma medium consists of heart infusion, peptone, yeast extract, salts, glucose or arginine, and horse serum (5 to 20 percent) Mycoplasma pneumonia Mycoplasma pneumonia (MP) is a contagious respiratory infection. Every year almost 2 million Americans are treated for MP. The disease is easily spread through contact with respiratory fluids, and it causes regular epidemics.  Mycoplasma and Ureaplasma species are not part of the normal vaginal flora. Some Mycoplasma species are spread through sexual contact. Infertility Some mycoplasmae have a negative effect on fertility. M. hominis causes male sterility/Genitals inflammation in humans. Infant mortality Low birth-weight, preterm infants are susceptible to Mycoplasma infections.  Links to cancer Several species of Mycoplasma are frequently detected in different types of cancer cells. These species are: M. fermentans M. genitalium M. hyorhinis M. penetrans  Risk factors elderly people people who have immune-compromising diseases (e.g. HIV) people who have lung disease people who have sickle cell disease children younger than age 5  Antibiotics first choice of antibiotics for children, include: erythromycin clarithromycin roxithromycin Azithromycin Antibiotics prescribed for adults include: doxycycline tetracycline quinolones  Rickettsia Rickettsia is a genus of non-motile, Gram-negative, non-spore forming, highly pleomorphic bacteria That can present as cocci (0.1 μm in diameter), rods (1–4 μm long) or thread-like (10 μm long). Being obligate intracellular parasites, the Rickettsia survival depends on entry, growth, and replication within the cytoplasm of eukaryotic host cells (typically endothelial cells). Because of this, Rickettsia cannot live in artificial nutrient environments and is grown either in tissue or embryo cultures (typically, chicken embryos are used) Found in ticks, lice, fleas, mites, and mammals  Pathogenesis Rickettsia species cause Rocky Mountain spotted fever, rickettsialpox, other spotted fevers, epidemic typhus, and murine typhus Rickettsia and Orientia species are transmitted by the bite of infected ticks or mites or by the feces of infected lice or fleas From the portal of entry in the skin, rickettsiae spread via the bloodstream to infect the endothelium and sometimes the vascular smooth muscle cells Rickettsia species enter their target cells, multiply by binary fission in the cytosol, and damage heavily parasitized cells directly  Typhus fever Ty p h u s i s a n i n f e c t i o u s d i s e a s e characterized by fever, headache, and a prominent rash which starts centrally on the trunk, and then spreads centrifugally to the limbs Typhus fever is a group of rickettsial diseases associated with insects, including human body lice, mites, and fleas A rash is observed in 20 to 80% of patients, the rash is usually macular but can be papular or purpuric in severe case  Diagnosis and treatment Diagnosis of rickettsial infections is often difficult The clinical signs and symptoms (e.g., fever, headache, nausea, vomiting, and muscle aches) resemble many other diseases  dengue / malaria A history of exposure to the appropriate vector tick, louse, flea, or mite is helpful but cannot be relied upon. Observation of a rash, which usually appears on or after day 3 of illness, should suggest the possibility of a rickettsial infection but, of course, may occur in many other diseases also Early treatment with doxycycline, tetracycline, or chloramphenicol is effective in controlling the infection Human infections are prevented by control of the vector and reservoir hosts  Chlamydia These bacteria are gram-negative, anaerobic, intracellular obligates that replicate within eukaryotic cells Chlamydia infection is a common sexually transmitted infection in humans caused by the bacterium Chlamydia trachomatis Globally, it is the most common sexually transmitted infection In females, the cervix is the anatomic site that is most commonly infected This can manifest as cervicitis, urethritis, pelvic inflammatory disease, perihepatitis, or proctitis. Chlamydial infections in women, especially if untreated, increase the risk of infertility and ectopic pregnancy In men lead to urethritis, epididymitis, prostatitis, proctitis, or reactive arthritis The bacterium is transmitted through direct contact with infected tissue, including vaginal, anal, or oral sex, and can even be passed from an infected mother to the newborn during childbirth  C. trachomatis is naturally found living only inside human cells. Chlamydia can be transmitted 1. during sex, 2. can be passed from an infected mother to her baby during childbirth.  Symptoms a yellowish vaginal discharge that might have a foul odour discharge from the penis painful burning during urination pain in the lower abdomen  Complications associated with chlamydial infection Pelvic inflammatory disease (PID), a serious condition that can permanently damage the fallopian tubes, uterus, and ovaries (this can cause infertility and chronic pain) Inflammation of the liver resulting in pain on the right side Doxycycline is an alternative, but azithromycin is preferred as it is a single-dose therapy. Other alternatives include erythromycin, levofloxacin, and ofloxacin. Poliomyelitis Tuberculin result Blood smear show Plasmodium parasite infecting red blood cells  Case study Cory, a nineteen year old college student, has been experiencing some pain for the last couple of days during urination. On one occasion, he observed a small amount of yellowish discharge from the tip of his penis. He realized his symptoms could indicate a sexually transmitted disease and figured that he must have contracted it from his girlfriend Julie. Cory and Julie had been seeing each other for about 3 months and had just recently become sexually intimate. Julie assured Cory that she had been faithful to him for the entire time that they had been together. Cory questioned whether Julie was being honest with him, but also had the feeling that Julie was wondering if he had been unfaithful to her.Cory went to the college health center and provided a urine sample that would be used to test for sexually transmitted disease. He returned the following day to find that he had tested positive. Identify the type of infection.  Sample answer Chlamydia is a common STD that can infect both men and women. It can cause serious, permanent damage to a woman's reproductive system, Chlamydia can be transmitted by having vaginal, anal, or oral sex with someone who has chlamydia. During the pregnancy the Chlamydia can passes to the featus which may result in severe complications Sexually active young people are at a higher risk of getting chlamydia. This is due to behaviors and biological factors common among young people.  Most people who have chlamydia have no symptoms. If you do have symptoms, they may not appear until several weeks after you have sex with an infected partner. Even when chlamydia causes no symptoms, it can damage your reproductive system. Women with symptoms may notice An abnormal vaginal discharge; A burning sensation when urinating. Symptoms in men can include A discharge from their penis; A burning sensation when urinating; Pain and swelling in one or both testicles (although this is less common). Men and women can also get infected with Chlamydia in their rectum, either by having receptive anal sex, or by spread from another infected site (such as the vagina). While these infections often cause no symptoms, they can cause Rectal pain; Discharge; Bleeding.  There are laboratory tests to diagnose chlamydia. Chlamydia can be cured with the right treatment. Medication for chlamydia should not be shared with anyone. Repeat infection with chlamydia is common. Prevention of the neonatal eye disease depends upon diagnosis and treatment of the pregnant woman Safe sex practices and on early diagnosis an treatment of infected persons