Fungal Infections

Fungi are basically "simple" plants. Although widespread in nature, there are only a few that can affect the human body.

These fall into two groups:-

  • Dermatophytes

    and

  • Yeasts


Dermatophytes are responsible for the majority of fungal infections that affect the body. They survive on dead keratin (a protein found in the nails, hair and the outermost layer of skin). When immunosuppression is involved the dermatophyte infection can penetrate into deeper layers of skin and in extremely severe cases can affect the body systemically.

There are three types of dermatophytes:
  • Trichophyton – infecting the hair, nails & skin

  • Microsporum – infecting the hair and skin

  • Epidermophyton – infecting the skin & nails



Yeast infections are more commonly caused by Candida albicans. Over 100 species of the yeast genus have been identified – most of which do not affect the human body. Candida albicans and other human pathogenic species usually colonize the human gastrointestinal tract. Bowel colonization affects between 40-60% of the population and this increases after any antibacterial/antibiotic medications. Throat and oral colonization affects approx. 20% of healthy individuals, while 13% of women are affected vaginally due to antibiotic treatment, pregnancy and oral contraception.

DERMATOPHYTES

TINEA CAPITIS (Ringworm of the scalp)


Tines capitis most often presents in pre-adolescent children. It is highly infectious and can be spread by direct contact, clothing, hairdressing implements or contact with infected animals.

If infected by the fungi from animal contact, the resulting lesions are more intensly inflamed than those caused by the fungi that has been transmitted person to person.

Most cases of tinea capitis begins with one or several patches of scaling and/or hair loss (alopecia).

“Gray Patch Ringworm” – presents as round or irregular scaly lesions of greyish-white patches. The hair breaks off at about 3-4mm above the skin surface. The hair roots are often covered in a “sheath” of white debris. Normal healing rarely results in any scaring.

“Kerion” – an extremely painful swollen and purulent inflamed nodule with multiple dark red, round or oval abscesses in various stages of formation. Pus is often draining from one or more ruptured abscesses which gives a “honeycomb” appearance to the skin surface. The hair falls out rather than breaking off. In extremely severe cases the entire scalp can be infected.

“Favus” – rare in Western countries, this form of Tinea capitis is caused by Trichophyton schoenleinii. Accompanied by extensive hair loss, which can become permanent. Scaring and thick yellowish brown crusts (scutula) develop, giving off a putrid odour.

TINEA MANUUM (Ringworm of the Hand)


A chronic dermatophytosis of the hands caused by Trichophyton rubrum, involving the palm and the webbing between the fingers.

It occasionally can also infect the back of the hands and can be accompanied by Tinea pedis (Athlete’s Foot). In its initial presentation small transparent pinpoint vesicles appear. These quickly rupture and as they dry up the hands become covered in layers of fine, white scales. If left untreated the affected skin becomes extremely dry, thickened and rough. Fissures or cracking will result, often causing pain and difficulty in bending or stretching of the fingers. The nails may also become infected.

TINEA PEDIS (Athlete’s Foot)


This condition is most commonly caused by Trichophyton rubrumm. It affects the webbing between the toes and the soles of the feet. The top of the feet and occasionally the ankles may also be involved.

A streptococcus bacteria can also invade the infected site causing localized infection. In more severe cases, cellulites (inflammation of the subcutaneous tissue) and lymphangitis (redness & inflammation of the lymphatic vessels, seen as red streaks in a streptococcal infection) can also occur.

Tinea pedis is quite common in adults, especially in young males. Highly infectious, it can be spread easily in communal areas such as changing rooms, showers or swimming pools. The condition is aggravated by hot “sweaty” weather and further inflamed by wearing tight-fitting shoes or sports runners.

There are three basic presentations of this condition:-

INTERDIGITAL


  • Lesions are commonly between the toes and between the sole border with the toes. The fourth and fifth toe spaces are more frequently infected.
  • Small vesicles are the first indication. They easily rupture when rubbed and the resulting “oozing” fluid gives off a distinctive “fishy” smell. The skin softens and turns white and after peeling develops a bright red appearance.
  • Some cases it presents as dry, rough skin which may be itchy and cracked.
  • Subsequent infection by other bacteria is common.
  • It is often worse in winter, tending to improve in warmer weather (probably due to the fact open or no shoes are worn and the feet can “breath”).
  • Reoccurences are possible.



MOCCASIN

  • Presents with a “shoe” like appearance over the entire foot and sometimes the ankle. The skin is dry and scaly and the sole may appear as a red or even whitish colour.
  • Frequently seen in patients who also have Tinea manuum.
  • Can be accompanied by infected nails.
  • Treatment is more difficult, however, good results can be achieved.


VESICULAR


  • Vesicles evolve rapidly either on the sole or top part of the foot. On the sole they often “collect” as groups, underneath the thickened skin.
  • May also present as large bullae (blisters). The vesicles eventually rupture. Upon drying, peeling occurs leaving a reddened base. This presentation resembles an allergic contact dermatitis.
  • Can also be accompanied by infected nails and secondary bacterial infections.



TINEA UNGUIUM (Ringworm of the nails)


Infection of the nail plates of the fingers or toes is commonly caused by Trichophyton metagrophytes or Trichophyton rubrum.

The infection can be primary or secondary. Primary infections often develop following external injury to the nail. Secondary infections result from a “spread” of the infective organism from pre-existing skin infections of the hands/feet.

  • As one gets older, the likelihood of nail infections increases.
  • The toe nails more likely infected than the fingernails. The nail of the big toe is the most common site of infection.
  • The nail becomes progressively opaque, yellow and thickened. Eventually the whole nail plate becomes infected and the nail starts to separate from the bed.
  • In severe cases the nail has difficulty in re-growing as it is deformed and weakened and breaks or fragments easily.

TINEA BARBAE (Ringworm of the beard)


This conditions affects mainly men and involves the beard and moustache regions of the face. It is due to the invasion of the hair follicle by dermatophyte Trichomychosis.

It presents as pustular folliculitis with red, inflamed and painful papules, nodules or pustules. The hairs are “loose” and can be easily removed. Commonly found on the upper lip, it can in extreme cases, spread to the cheeks, eyelids, eyebrows and even the forehead. If these areas are involved, the presentation is completely different, usually showing a sharply marginated redness with fine scaling over the affected area.

TINEA FACIALIS (Ringworm of the face)


More common in children, the condition is often misdiagnosed because of its presentation. It usually affects the cheeks, chin, nose and upper lip and is characterized by a well defined red patch. It can be extremely itchy and often results in a scoured, bloody ruptured appearance. It can be accompanied by white/yellowish scaling. It normally starts in one or two small areas that centrally progress outwards. It can also be light (photo) sensitive.

TINEA CORPORIS (Ringworm of the body)


A superficial dermatophyte infection of the “smooth” skin of the body – trunk, neck and limbs - but excluding the feet, hands and groin. The main fungi responsible are Microsporum and Trichophyton.

Lesions start with “grouped” papules of papulovesicles, which gradually increase in number and size. Singular or multiple, sharply defined circular, semicircular or concentric “edges” occur, forming “rings”. These “rings” are usually very red. As the centre heals, the elevated surrounding edge continues to erupt in clusters of papules or papulovesicles. It continues to spread out and a concentric pattern forms.

Fine scaling and mild to severe itching that accompanies the condition, is often worse in the summer. Cooler weather breaks the cycle only to reoccur the following summer.

TINEA CRURIS (Jock Itch)


A condition that almost exclusively affects adult men in the groin and genital area. It is worse in Summer due to sweating. It can still occur in Winter if heavy, multi-layered clothing is worn. It can also be transmitted through sexual contact.

In the initial stages the condition presents as a red scaly patch within a flexural fold, i.e. groin. This spreads gradually from the flexural fold to the thigh and buttocks. The patch is marked by a narrow, raised, well-defined inflamed edge. Small vesicles or pustules may form within the area. As the “centre” heals, hyperpigmentation, which is temporary, develops. The spread of the circular, semicircular or concentric patches is even.

It can spread to the scrotum with severe localized itching.

Although Epidermophyton floccosum is the main cause of this condition, Trichophyton rubrum can also be responsible.

If Trichophyton rubrum is the cause the onset is usually considerably slower. The lesions associated with this type of infection can spread as far as the abdomen and the lower back. This form is extremely painful.

Seconday bacterial infections can also increase the severity of the condition.

CANDIDIASIS


It is commonly caused by the yeast, Candida albicans and less often by other yeast strains.

Candida albicans is a normal inhabitant of the gut, vaginal tract and the mouth. Certain predisposing factors such as obesity, pregnancy, diabetes, the taking of oral contraception, antibiotics or the application of topical steroids, heat or immune dysfunction, cause the yeast to colonize out of control.

The yeast usually only infects the outer layers of the skin, spreading under the outer layer and causing it to lift and peel. Accompanied generally by intense redness which leaves a bare, glistening surface. It colonizes in the body folds affecting the skin under the breasts, the genitals, nail plate, mouth, face and scalp, and between the toes or fingers.

In people who are immune compromised the condition can become systemic. Invasion of the blood vessels can occur with widespread infection of the gastro-intestinal tract, trunk and extremities. May also present as a secondary infection in conditions such as eczema.
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