Candida albicans are saprophytic diploid fungus commonly found in
the microflora of body cavities. They grow as both yeast and
filamentous cells and can cause oral and genital infections especially
in compromised immune systems (immunocompromised). Due to their ability
to rapidly proliferate, the fungus has become one of the major reasons
for hospital-acquired infections (HAI).
Candida albicans is
commonly found in the human gut in small numbers. The standard format of
existence is in the form of a single ovoid yeast cell. The fungus grows
in the same form when cultured in a laboratory medium. In the normal
state, it does not cause any problem as the helpful bacteria in the gut
can easily control the fungi. In this condition it is unable to
penetrate the linings in the digestive tract and no antibodies are
produced by the body to suppress the dormant population.
However,
Candida albicans may proliferate in certain cases resulting in the
prototypic opportunistic disease, Candidiasis. The causes are generally
nonimmunogenic such as antibiotics, diabetes and pregnancy, among others
or immunologic under which the immune system is unable to stop the
proliferation. During this period, the yeast can affect various organs
in the body and cause a range of health problems. One of the primary
reasons for these infections is the use of antibiotics that damage the
physiological and mucosal flora killing both harmful and helpful
bacteria, and impair the walls of the digestive tract. Steroids and
birth control pills are also responsible for catalysing this growth.
The
body's humoral response to the overgrowth is an immune reaction
triggered by the macromolecules present in extracellular fluids. The
glycoprotein immunoglobulin comprises of five classes, IgA, IgD, IgE,
IgG and IgM which act as effector molecules in the humoral response to
yeast infections. IgG makes up approximately 75% of the total
immunoglobulins in the plasma of normal healthy people while the rest
comprise the remaining 25%. The IgA antibody is present in both serum
and secretory (sIgA) forms.
The IgG antibodies are generated by
the plasma B cells after isotype switching and appear during the
maturity of the antibody reaction after repeated contact with antigens.
IgG mostly plays a role in secondary immune response due to its delayed
appearance and is characterised by relatively high affinity and ability
to exist for a longer time. The antibodies bind and coat the pathogens
resulting in their immobilisation and takeover by phagocytic immune
cells. They also activate the immune protein production in the
complement system which helps remove the pathogens. The humoral response
to Candida albicans can be studied by enzyme immunoassays. IgA, IgG and
IgM assays help detect antibodies against the fungus in human serum.
In
healthy human beings, the antibodies are generally able to prevent the
yeast infections from affecting other body organs. However, in
immunocompromised patients, the fungus can reach the blood and cause
Candidaemia. Inadequate and delayed treatment of the disease has been
identified as one of the major reasons for increased mortality in
hospitalised patients. It is therefore extremely important that proper
tests are conducted at the earliest and effective treatment initiated
under expert guidance of specialist doctors without any delay.
