Microbiology and Immunology

Mycoplasma infections WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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aspergillosis. As well, a more invasive infection via the blood-

stream can result in mold growth in the eye, heart, kidneys,

and the skin. The invasive infection can be lethal.

Mycologists are becoming increasingly involved in the

remediation of buildings. The so-called “sick building syn-

drome” is often due to the growth of fungi, particularly molds,

in the insulation of buildings. The growth of the molds includ-

ing Cladosporium, Penicilium, Alternaria, Aspergillus,and

Mucorcan produce allergic reactions ranging from inconven-

ient to debilitating to building users.

See alsoCandidiasis; Economic uses and benefits of microor-

ganisms; Slime molds

MMycoplasma infectionsYCOPLASMA INFECTIONS

Mycoplasma are bacteriathat lack a conventional cell wall.

They are capable of replication. Mycoplasma cause various

diseases in humans, animals, and plants.

There are seven species of mycoplasma that are known

to cause disease in humans. Mycoplasma pneumoniaeis an

important cause of sore throat, pneumonia, and the inflamma-

tionof the channels in the lung that are known as the bronchi.

Because of the atypical nature of the bacterium, mycoplasma-

induced pneumonia is also referred to as atypical pneumonia.

The pneumonia can affect children and adults. The symptoms

tend to be more pronounced in adults. In fact, children may not

exhibit any symptoms of infection. Symptoms of infection

include a fever, general feeling of being unwell, sore throat,

and sometimes an uncomfortable chest. These symptoms last

a week to several months and usually fade without medical

intervention.

Mycoplasma pneumoniaecan also cause infections in

areas of the body other than the lungs, including the central

nervous system, liver, and the pancreas.

Another species, Mycoplasma genitalium, is associated

with infections of the urethra, especially when the urethra has

been infected by some other bacteria. The mycoplasma infec-

tion may occur due to the stress imposed on the immune sys-

temby the other infection.

A mycoplasma called Ureaplasma urealyticumis pres-

ent in the genital tract of many sexually active women. The

resulting chronic infection can contribute to premature deliv-

ery in pregnant women. As well, the mycoplasma can be trans-

mitted from the mother to the infant. The infant can contract

pneumonia, infection of the central nervous system, and lung

malfunction.

A group of four mycoplasma species are considered to

be human pathogens and may contribute to the development

an immunodeficiencyvirus infection to the more problematic

and debilitating symptoms of Acquired Immunodeficiency

Syndrome (AIDS). The species of mycoplasma are

Mycoplasma fermentans, Mycoplasma pirum, Mycoplasma

hominis, and Mycoplasma penetrans.

Mycoplasma have also been observed in patients who

exhibit other diseases. For example, studies using genetic

probes and the polymerase chain reactiontechnique of detect-

ing target DNAhave found Mycoplasma fermentans in

upwards of 35% of those afflicted with chronic fatigue syn-

drome. The bacterium is present in less than 5% of healthy

populations. Similar percentages have been found in soldiers

of the Persian Gulf War who are exhibiting chronic fatigue-

like symptoms. While the exact relationship between

mycoplasma and the chronic fatigue state is not fully clear, the

current consensus is that the bacteria is playing a secondary

role in the development of the symptoms.

Over 20 years ago, mycoplasma was suggested as a

cause of rheumatoid arthritis. With the development of molec-

ular techniques of bacterial detection, this suggestion could be

tested. The polymerase chain reaction has indeed detected

Mycoplasma fermentansin a significant number of those

afflicted with the condition. But again, a direct causal rela-

tionship remains to be established.

The association of mycoplasma with diseases like

arthritis and chronic fatigue syndrome, which has been impli-

cated with a response of the body’s immune system against its

own components, is consistent with the growth and behavior

of mycoplasma. The absence of a conventional cell wall

allows mycobacteria to penetrate into the white blood cells of

the immune system. Because some mycoplasma will exist free

of the blood cells and because the bacteria are capable of slow

growth in the body, the immune system will detect and

respond to a mycobacterial infection. But this response is gen-

erally futile. The bacteria hidden inside the white blood cells

will not be killed. The immune components instead might

begin to attack other antigens of the host that are similar in

three-dimensional structure to the mycobacterial antigens.

Because mycoplasma infections can become chronic, damage

to the body over an extended time and the stress produced on

the immune system may allow other microorganismsto estab-

lish infections.

The polymerase chain reaction is presently the best

means of detecting mycoplasma. The bacteria cannot be easily

grown on laboratory media. Labs that test using the poly-

merase technique are still rare. Thus, a mycoplasma infection

might escape detection for years.

Strategies to eliminate mycoplasma infections are now

centering on the strengthening of the immune system, and

long-term antibiotic use (e.g., months or years). Even so, it is

still unclear whether antibiotics are truly effective on

mycoplasma bacteria. Mycoplasma can alter the chemical

composition of the surface each time a bacterium divides.

Thus, there may be no constant target for an antibiotic.

See alsoBacteria and bacterial infection; Bacterial mem-

branes and cell wall

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