Nail Infections

Posted August 20, 2022 by Anusha ‐ 6 min read

Nail infection, as the name suggests, is an infection affecting the fingernails or toenails. It can be caused by the growth of bacteria, fungus or virus in these areas. Fungal nail infection is more commonly seen to affect toenails, while bacterial nail infection is more likely to occur following an injury to the surrounding skin.


Nail infections are commonly caused by bacteria like Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas, or fungi like Trichophyton, Microsporum, Epidermophyton, and Candida Albicans.


Bacterial nail infection

If the infection is caused by bacteria like Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas, it is called a bacterial nail infection or Paronychia. Based on the duration for which the nail infection persists, bacterial nail infections are divided into the following types -

Acute bacterial nail infection

This type of infection is caused by bacteria that cause inflammation in the surrounding areas. It may last for less than six weeks, causing pain around the area.

Chronic bacterial nail infection

This type of infection is also caused by bacteria that cause inflammation in the surrounding areas. It lasts for more than six weeks, causing periodic, painful flare ups.

Fungal nail infection

If the infection is caused by fungi like Trichophyton, Microsporum, Epidermophyton, Candida Albicans, it is called a fungal nail infection or Onychomycosis. Based on the area involved or the causative agent, fungal nail infections are further divided into the following subtypes -

Distal subungual onychomycosis

This is the most common type of onychomycosis where the fungal infection starts from the nail bed and spreads across the edges.

Proximal subungual onychomycosis

It is a rare type of onychomycosis which is usually seen in patients who suffer from immunocompromised states. The infection begins as white spots in the center of the nail and moves outward as the nail grows.

White superficial onychomycosis

This type of infection affects only the surface of the nail. It may cause white spots on the surface of the nail that turns powdery and can make the nail crumble.

Candida onychomycosis

This is caused by a fungus called Candida albicans. It is more commonly seen in nails that have been previously affected by injury or infection.

Viral nail infection

Viral warts can cause changes in the shape and thickness of the nails leading to a viral nail infection. It is usually caused by Human Papillomavirus (HPV). In some cases, viruses can also lead to skin growth under the nail, known as Periungual warts. It may also lead to a condition known as Onychomadesis in which the nails begin to shed at the proximal end.


Nail infection should be suspected if the following changes are seen in the nails:

  • Occurrence of white or yellow spots on the nail

  • Whitish or yellowish discoloration of the nail

  • Thickening of the nail

  • Brittle, crumbly, and easily breakable nails

  • The shape of the nail is distorted

  • Foul smelling nails

  • Pain, redness, swelling in the nails and surrounding area in cases of acute bacterial nail infection

  • Yellow pus formation and discharge from the nail in paronychia

  • Accompanying fever in acute bacterial nail infection


Doctors can usually determine the type of nail infection based on the presenting symptoms and history. The symptoms of nail infection may appear as patchy discoloration or flaking of the nail, brittle nails, alteration in the shape of the nail, pus formation, swelling, etc. Certain laboratory tests may be suggested to confirm the exact cause of nail infection, such as:

Suspected bacterial nail infection

  • Complete blood count (CBC), Erythrocyte sedimentation rate in cases of fever accompanying acute bacterial nail infection.

  • Pus culture to identify the causative microorganism in the pus.

  • Nail clippings for culture and direct microscopic examination.

Suspected fungal nail infection

  • Nail clippings for culture and direct microscopic examination.

  • Fungal susceptibility testing to test the response of antifungal drugs.

  • KOH testing - Also called potassium hydroxide test, is used for the diagnosis of fungal infection in the skin, hair, and nails.

  • PCR testing - Polymerase Chain Reaction (PCR) testing is used to improve sensitivity in detecting the causative fungi in nail specimens from patients with suspected Onychomycosis (a fungal infection that occurs in the edge of the nail).


Oral antibiotics

Usually, simple bacterial nail infections can be managed at home with topical antibiotic creams. Oral antibiotics are prescribed in more severe stages of infection. Available medicines are:

  • Ampicillin

  • Doxycycline

  • Clindamycin

Oral antifungals

Antifungals are given as oral medications to treat fungal nail infections. Available medicines are:

  • Itraconazole

  • Fluconazole

  • Terbinafine

Topical antibiotics

  • Mupirocin: It is an antibiotic medicine used to treat bacterial infection. It kills the bacteria that cause skin infections by preventing the synthesis of essential proteins necessary for the survival of bacteria. Thus, it prevents the infection from spreading.

  • Fusidic acid: It is an antibiotic that works by preventing synthesis of essential proteins required by bacteria to carry out vital functions. Thus, it stops the bacteria from growing, and prevents the infection from spreading.

  • Retapamulin: This antibiotic is helpful in treating bacterial infection by inhibiting the bacteria from growing, and prevents the infection from spreading.

Topical antifungals

These are available as creams, absorbent powders, or solutions for dressing to be applied directly to the infected nail:

  • Ciclopirox: These are available in a cream form or lacquer form that can be applied like a nail polish over the infected nail. They work by inhibiting protein synthesis in the fungal cells, thereby preventing further growth of the fungi.

  • Amorolfine: These are to be applied directly to the nails. They work by inhibiting the enzymes necessary for growth of fungal infection.

  • Antifungal dusting powder to prevent moisture in the affected area.

Topical antiseptics

In acute bacterial nail infection, the affected part may be soaked in a diluted antiseptic solution and can then be covered with antibiotic ointments. A few examples of antiseptics are:

  • Povidone Iodine: Povidone Iodine is an antiseptic. It kills harmful infections causing microorganisms to prevent and treat infections.

  • Chlorhexidine: It is a disinfectant and antiseptic that is used for skin disinfection. It is also used for cleaning wounds, preventing dental plaque, and treating yeast infections.

Topical steroids

This class of drugs are the most powerful medicines used to lower inflammation in the body. When applied topically, it relieves the redness, swelling, itching and irritation of the skin that is caused due to nail infection. Methylprednisolone aceponate cream is the most common medicine used.


In cases of severe nail infection, like collection of pus around the nail or the formation of abscess (pus), surgery may be required to drain the pus or abscess and remove the nail in extreme cases of disfigurement.

Laser therapy (Phototherapy)

This is a treatment for fungal nail infection (onychomycosis). The laser devices emit a pulse of energy that penetrates through the toenail to the nail bed where the fungal growth is present. Fungal infections of the nails usually require several laser treatment sessions before they completely resolve.

diseases disorders fungal-infection nail-infections viral-infections

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