Antimicrobials – antifungals
John Steele and Jenny Taylor
- • Introduction
- • Oral fungal infections
- • Anti-fungal drug treatment
- • Implications for dental practitioners
- • To be familiar with the potential drug interactions of anti-fungal medications used to treat oral infections.
- • To be aware of the risk factors for oral candidosis.
This chapter discusses the therapeutic agents used to treat fungal infections (mycoses) and to consider the implications for the dental practitioner. Initially, a broad overview of the various types of fungal infections will be provided. This will include a section specifically relating to those fungal infections that may present in the oral cavity. Then the different classification of antifungal medications will be summarized.
Fungal infections are more commonly seen in patients who are immunocompromised resulting in an increased susceptibility to acquiring an infection. Patients undergoing chemotherapy as part of cancer treatment or taking immunosuppressant medication (e.g. after an organ transplant or for an autoimmune condition) can become immunocompromised. In addition, patients diagnosed with an immunocompromising disease (e.g. HIV) or diabetes are also at risk of a weakened immune system. Specific local factors can also predispose an individual to oral fungal infections and these will be discussed later. The chapter’s key topics are listed in Table 6.1.
Table 6.1 Key topics
|Oral fungal infections|
|Skin and nail infections|
|Implications for dental practitioners|
Aspergillosis is acquired from inhaling the aspergillus mould which is found in vegetation and crops as well as within the home in, for example air conditioning units. It mainly affects the respiratory system but can affect other organs such as the heart and skin in immunocompromised individuals. It can cause infection, growth of the fungus in the lungs or may initiate an allergic response.
There are different forms of the infection including, among others, aspergilloma, invasive aspergillosis, chronic cavitating aspergillosis and chronic fibrosing aspergillosis.
Symptoms include cough, haemoptysis, weight loss and fatigue.
Single aspergillomas may be amenable to surgery. The drug treatment of choice for aspergillosis is voriconazole. Amphotericin is an alternative. Refractory infections can be treated with caspofungin, itraconazole or posaconazole.
Blastomycosis is caused by the fungus Blastomyces dermatitidis which is found in moist soil and decomposing vegetation. The infection is acquired through inhaling fungal spores.
Many people who inhale the spores do not become symptomatic. Those who do develop symptoms generally develop a flu-like illness: fever, cough and muscle and joint pain.
The drug treatment of choice is either amphotericin or itraconazole.
Cryptococcal infections are caused by either Cryptococcus neoformans or Cryptococcus gattii both of which are fungi that are found in soil. They can infect the lungs and nervous system. Cryptococcal meningitis can be life-threatening especially in an immunocompromised patient with HIV infection. Fungal growths (cryptococcomas) can develop within organs.
Respiratory symptoms include a cough, fever and dyspnoea. Neurological symptoms include those seen in meningitis such as headache, photophobia, neck pain, nausea and vomiting.
For cryptococcal meningitis or severe pulmonary infections the treatment of choice is intravenous amphotericin in combination with intravenous flucytosine followed by fluconazole. Mild-moderate pulmonary infections can be treated with fluconazole alone. Surgery can sometimes be required to remove fungal growths.
Histoplasmosis is caused by the Histoplasma fungus which is found in soil particularly where there are bird or bat droppings. It is acquired through the airborne route and inhaled. Many people who inhale the spores have subclinical infection and do not require treatment. However, histoplasmosis can be a serious infection for the immunocompromised individual.
Many people have no symptoms. Those that are affected often experience a flu-like illness (fever, cough, fatigue, aches) and many do not require treatment as the infection is self-limiting and resolves of its own accord.
Those patients that do require treatment may need intravenous amphotericin for severe infections or can be treated with itraconazole if they are immunocompetent and they have a less severe non-meningeal infection.