Mycoplasma+pneumoniae

Taxonomic Classification:
Kingdom - Bacteria Division - Firmicutes Class - Mollicutes Order - Mycoplasmatates Family - Mycoplasmatacae Genus - Mycoplasma Species - Mycoplasma pneumoniae

Mycoplasma pneumoniae is a small unicellular organism belonging to the kingdom Bacteria. Being a gram positive bacteria puts it in the division Firmicutes. Mollicutes are a class of cell wall-less organism and the order Mycoplasmatates and family Mycoplasmatacae have only two members, Mycoplasma being one of them. Mycoplasms are cell wall-less parasites of vertebrate hosts, Mycoplasma pneumoniae is the species that effects humans and is known to cause Primary Atypical Pneumonia.

Background and History
Although M. pneumoniae was probably around for much longer, this microbe was first discovered in a patient in 1944 who presented with signs and symptoms of atypical pneumonia. The bacteria was first thought to be a fungus or virus, thus the name Mycoplasma which is Greek for fungus-formed. It was later determined to be a bacterium, however one with some unique characteristics. The major difference being the lack of a rigid cell wall common in gram negative and gram positive bacterium. M. pneumoniae also has the distinction of being the smallest organism able to live and reproduce on its own, at least in a parasitic-host relationship with humans. M. pneumoniae receive there nutrition, such as fatty and amino acids, nucleic acid synthesis precursors and cholesterol from the surface respiratory tract epithelial cells. This pathogen is most tied to tracheobronchitis and primary atypical pneumonia or walking pneumonia.

M.pneumoniae is a filamentous or spherical cell wall-less bacteria and because of this structural difference is susceptible to osmotic instability in the environment. With the lack of a cell wall, other adaptations have been made such as a rigid fibrous cytoskeleton that helps it maintain its shape. The cytoskeleton is made up of numerous fibrous proteins around 80-100nm wide by 250-300nm long, serving a range of functions such as support, motility, energy metabolism, translation, and host cell attachment. A couple important proteins are the "Neimark protein" thought to act much like actin in human muscle and is responsible for movement, and the "adhesion proteins" (P30, P40 and P90 proteins) allowing the M. pneumoniae cell to bind to the host cell. The cytoskeleton is surrounded by a plasma membrane unlike most Eukaryotas, consisting of a triple-layered cell membrane and unlike other bacterium contains cholesterol and serol-like molecules for support.



Transmission and Risk Factors
Mycoplasma pneumoniae is usually transmitted by inhalation of aerosolized particles of bacterium often released through a cough or a sneeze. A less common mode of transmittion can happen when the bacterium enters through an open wound into the blood stream. Upon entering the host, the bacterium travels into the lungs and takes up residence and begins multiplying. Due to its mode of transmittance, ideal conditions for contraction are crowded living and working conditions as found in prisons, schools, offices, and hospitals. Mycoplasmic pneumonia has a greater prevalence in young adults and children over the age of four (pre-school age).

Pathology
Mycoplasma pneumoniae is a parasitic bacterium that effects the epithelial cell lining of the respiratory tract of its host causing atypical pneumonia and less common pharyengitis and bronchitis. It is believed that the lack of a cell wall, the closeness of its plasma membrane to its host's plasma membrane and its adhesion proteins allow for a kind of binding of membranes that allows Mycoplasma pneumoniae to share host nutrients and exchange of mycoplasmal cytoplasmic constituents such as hydrolytic enzymes. The injection of bacterial contents into the host cell is responsible for the production of hydrogen peroxide (H2O2) and super-oxide radicals (O2-) that harm host tissue and may be the cause of production of various cytokines responsible for the initiation of the bodies inflammatory process. Mycoplasmic pneumonia is just one type of pneumonia that accounts for about 20% of all pneumonia cases, called "atypical" because the signs and symptoms are usually more mild and often do not require medical attention. Other types of pneumonia include bacterial pneumonia, fungal pneumonia, viral pneumonia, chemical pneumonia, and parasite pneumonia.

Diagnosis
Some tests to determine if Mycoplasma pneumoniae is culpable are sputum culture, serum testing, cold agglutinins, enzyme immunoassay, CBC counts, erythrocyte sedimentation rates, and chest radiography. Mycoplasmic pneumonia commonly presents with a cough, sore throat, low fever and middle ear discomfort.

Treatment
If treatment is necessary, antibiotics are generally given. Medications that target the cell wall like penicillin are not used to treat because of the lack of a cell wall. Antibiotics that disrupt or inhibit growth and translation are commonly used such as Azithromycin, Erythromycin, Clarithiomycin and Tetracycline. Prognosis is good and full recovery is expected.