Nocardia asteroides it is a strict aerobic bacteria, catalase positive that is widely distributed on the planet. It has been isolated from a multitude of environments, because its development requirements are not so demanding.
The genus Nocardia was discovered by Edmond Nocard, with Nocardia asteroides being one of the species that make it up. These bacteria are considered to be weak Gram positive and partially acid-alcohol resistant..
This bacterium is a known human pathogen, although its infections are increasingly rare, being almost relegated to people with affected immune systems. An example of these are people with HIV, with leukemia or transplants, among others.
Of all the pathologies that it can generate, pulmonary nocardiosis is the most common, while the most infrequent are extrapulmonary, such as keratitis or endophthalmitis. Prevention and treatment against this bacterium are important, since the consequences of late diagnosis can be lethal.
The taxonomic classification of Nocardia asteroides is as follows:
Species: Nocardia asteroides,
Bacterial cells of Nocardia asteroides They are shaped like bacilli with a diameter of approximately 0.5 to 1 micron. The distinctive feature of these bacilli is that they are branched and have right-angle subbranches. The bacteria are not surrounded by a capsule. There is also no presence of cilia or flagella.
In the cultures, colonies of variable appearance are appreciated, with a characteristic smell of humid earth and can be seen as white as chalk, brown pink or salmon.
The bacterium has a type IV cell wall, composed of peptidoglycan. It also has saturated mycolic acids, arabinose, galactose and 2,6 meso-diaminopimelic acid..
This bacteria is found on dead organic matter. It constitutes a fundamental element in the decomposition of organic matter, contributing to the fragmentation of large molecules into smaller ones that become part of the nutrients in the soil..
Because one of the components of its cell wall is mycolic acids, this bacterium cannot be stained effectively through the Gram method..
The vast majority of experimental staining processes involve bleaching that is carried out by acidic substances or alcohols. In the case of bacteria such as Nocardia asteroides, there is resistance to this discoloration because mycolic acids do not allow the passage of these substances.
Despite this, there are methods that allow its coloring. Specifically the Nocardia astroides is colored through the Kinyoun method. In this, carbol fuchsin is used as a dye and methylene blue as a contrast..
Like all living beings, Nocardia asteroides You must perform certain metabolic processes to obtain energy. For these processes requires mandatory oxygen.
Due to this, the bacteria must be located in environments where there is a high availability of this chemical element..
The bacterium is mainly found in a telluric habitat, that is, on land. It is also found in water, dust, and decaying vegetation..
This bacterium is not part of the normal microbiota of any living being, be it human or animal.
The Nocardia asteroides it does not require many demands to be able to develop. It can grow in a pH range between 6.9 and 9.0.
Likewise, the optimum growth temperature is 35-37 ° C. Despite this, cases have been seen where it has grown at temperatures as low as 12 ° C or as high as 48 ° C.
This bacterium synthesizes the enzyme catalase, whose function is to catalyze the conversion of hydrogen peroxide (HtwoORtwo) in water and oxygen, with the consequent appearance of bubbles.
When culturing this bacterium, it can take 48 hours to 4 weeks for colonies to appear..
Nocardia asteroides synthesizes the enzyme urease. This enzyme catalyzes the reaction through which the hydrolysis of urea occurs. The reaction is as follows:
CO (NHtwo)two + 2H+ + 2HtwoO - 2NH4+ + COtwo + HtwoOR
The Nocardia asteroides it is a widely known human pathogen. In fact, it is the species of the genus Nocardia that most commonly causes human infections.
This bacterium is associated with several pathologies, such as pulmonary nocardiosis, primary cutaneous nocardiosis, keratitis and endophthalmitis.
This is a disease of the lung tissue caused by the infection and uncontrolled proliferation of Nocardia asteroides there.
It occurs mainly when the bacteria is inhaled.
The symptoms that occur in this infection are similar to those of pneumonia. Among these are:
It is an uncommon and extremely rare infection. It attacks people who have a suppressed immune system, such as those who are HIV positive or who have had an organ transplant, among others.
It is an infection that is limited to one of the outermost layers of the eye, the cornea. When not treated properly, it can cause complete loss of vision in the affected eye..
It is an infection that affects all parts of the eye. It is caused by the penetration of the bacteria in the eye through an injury, by surgery or directly by the bloodstream.
As in any bacterial infection, the treatment to follow is with antibiotics. When making the diagnosis, the doctor is obliged to make a culture of the bacteria and determine which antibiotic the infecting strain is susceptible to..
Medications used to treat the above conditions include cotrimoxasol, sulfadiazine, sulfamethoxasol, minocycline, and trimetropin..
Likewise, sometimes, apart from drug treatment, surgical treatment is required, such as to drain purulent collections..