Mycoplasma are unique bacteria. They are very small and have no cell wall. There are more than 200 species known, 29 can infect humans and of these, 23 can cause disease.
Healthy individuals can fight these bacteria with their own immune systems. When infection occurs in people who have suppressed immunity, symptoms may become serious.
Mycoplasma are the smallest bacteria known. Because of their size, scientists initially thought it was a virus. They are so small that they can not be seen with an ordinary microscope. There fit 4000 Mycoplasma in a red blood cell; compared to only 12 Bartonella. In addition to the fact that these organisms are very small, they have some other unique features. Unlike other bacteria, they have no cell wall. Bacteria have a cell membrane that separates the interior of the cell from the outside environment.
Most bacteria developed additional protection in the form of a cell wall over time. Gram negative bacteria improved on this innovation and developed a double cell wall. This provides additional protection and makes gram negative bacteria more difficult to treat.
Mycoplasma are unique in this area because they are the only bacteria that have no cell wall. While other bacteria expanded their genome and properties, these organisms underwent an inverse process. As a result, they completely discarded their cell wall, creating a fairly unique shape.
Gram staining is a method by which bacteria can be visualized under a microscope. It serves as a tool in recognizing species. This method can distinguish between gram-positive and gram-negative bacteria due to the structural differences in their cell wall. Despite the lack of a cell wall, Mycoplasma is considered to be gram a positive bacterium.
History & strains
There are more than 200 different types of Mycoplasma, but just like other opportunistic co-infections, only recently the understanding of these organisms begins to increase. The very small size of the organism, the lack of a cell wall, and the demanding nutritional and environmental needs, made research into the organism complicated. The bacterium is difficult to culture because of these nutritional requirements and the small genome.
The first Mycoplasma was first isolated in 1937. In 1950, was found the organism in a cow and in 1954 the first Ureaplasma was discovered. In 1960 there was enough evidence to conclude that these different organisms formed a unique group of bacteria. The role of these bacteria in human disease is still largely unknown. In 1980 scientists discovered that they caused urinary tract infections in men.
Only since 1990 science became advanced enough to allow researchers to grow some of the Mycoplasma species in the laboratory. It was discovered by accident that most laboratory studies were contaminated with Mycoplasma, making some of the research invalid. This accident caused an increase of research into the DNA of these organisms. As a result, the nature of these bacteria began to become more visible.
The most important pathogenic Mycoplasma are: M. pneumoniae, M. genitalium, M. hominis, M. fermentans, M. penetrans, U. urealyticum and U. Parvum.
Reservoirs & vectors
Mycoplasma infect mammals, reptiles, fish, arthropods and plants. They are widespread in nature. All Mycoplasma, regardless of their host (animal or plant) cause similar diseases and most Mycoplasma are spread by insect bites.
Of the more than 200 known Mycoplasma species, 29 can infect humans; 23 of these are known to cause disease. Due to the increase in research, more Mycoplasma are found as a cause of human disease; much more than was previously thought.
Mycoplasma are common and can be spread through insect bites, via open wounds, inhalation, oral ingestion and sex.
Blood of the blood bank is not routinely screened for the presence of Mycoplasma and contamination via a blood transfusion might be possible. However, the bacteria rarely cause disease unless the immune system is (temporarily) under stress.
Mycoplasma are found in ticks, fleas, mites, mosquitoes, lice and biting flies. All of these are competent vectors, meaning they can transfer the organisms to the host they feed on. Ticks can transfer Mycoplasma to humans.
The effect of Mycoplasma on the body is much more complex than previously thought. It was believed that these organisms caused mainly pneumonia and urinary tract infections, but it becomes clear that Mycoplasma can cause systemic conditions and may be the cause of various chronic conditions.
Pneumonia: Up to 40% of all non-hospitalized pneumonia is caused by Mycoplasma. 20% of the patients who develop pneumonia from infection with these organisms have to be hospitalized.
The symptoms reported by patients varies: fever, malaise, headache, coughing sore throat, chills, ear pain, diarrhea, nausea / vomiting, chest pain and skin rashes with fever, cough, malaise and headache.
Eyes: conjunctivitis, uveitis, optic neuropathy, retinitis, iritis, ocular myasthenia gravis, optical disc swelling and sometimes permanent loss of vision.
Ears: Sudden hearing loss, tinnitus
Heart: Up to 10% of patients suffer from endocarditis, myocarditis, pericarditis, Kawasaki’s disease, and / or temporal arteritis.
Neurological: About 7% of patients develop neurological problems, of which more than 80% have no or only mild lung problems. The central nervous system often becomes inflamed. Demyelation of the nerve sheaths is common. Also reported: Chronic fatigue, encephalitis, aseptic meningitis, meningoencephalitis, cerebellar ataxia, polyradiculitis, transverse myelitis, Guillain-Barré syndrome, cranial and peripheral neuropathy, optical neuritis, diplopia, stroke and stratal necrosis, mental confusion, acute psychosis and coma.
Blood: Hemolytic anemia, intravasal clotting, aplastic anemia, thrombocytopenic purpura, thrombosis and Raynaud’s phenomenon. Vasculitis is common.
Gastrointestinal disorders: In 25% of patients, nausea, vomiting, abdominal pain, diarrhea, loss of appetite, cholestatic hepatitis and / or pancreatitis develops.
Joints: Mycoplasma is one of the main causes of rheumatoid arthritis. Successful treatment of the infection can cause a remission. There is a breakdown of synovial tissue in the joints with a lot of pain. Muscle aches and general joint pain plays a role in 15% of patients.
Skin: About 25% of patients develop skin manifestations. Usually self-limiting. Skin rash, urticaria and pityriasis rosea. Erythema multiforme. An infectious cause of Stevens-Johnson syndrome. In immunocompromised skin conditions are worse.
Different types of Mycoplasma are present in 15-75% of healthy Americans without further complaints. This percentage also seems to be going on for the rest of the world.
The PCR method can be performed quickly and the results are available within a few hours. This is essential in acute cases. Given the wide range of symptoms, differential diagnosis is difficult.
In case of Lyme infection, an additional Mycoplasma infection should always be considered.
Mycoplasma infections respond to macrolides, tetracyclines and fluoroquinolones. The newer ketolides are also promising.
Penicillins, beta-lactams, cephalosporins, vancomycin, sulfonamides, trimethoprim and rifampicin work on the cell wall of bacteria and therefore are not effective against Mycoplasma.
In general, doxycycline is the best (first) choice for Mycoplasma infections. However, this antibiotic can not always completely eradicate the infection.
There are several case reports requiring the addition of a fluoroquinolone, for at least 6 months, to cure the infection.
For urinary tract infections, azithromycin shows better results than doxycycline.
In most cases, doxycycline and/or azithromycin will treat an uncomplicated Mycoplasma infection. In the case of chronic disease, neurological complications and late diagnosis it is not unthinkable that Mycoplasma persists and has to be treated with long-term antibiotics.