11: Oral implications of infection in compromised patients

Chapter 11 Oral implications of infection in compromised patients

The term ‘medically compromised’ is often misused. The definition of a medically compromised patient is one who by virtue of their medical condition, or its treatment, is susceptible to infection and other serious complications. Conditions which cause patients to be medically compromised can either be congenital or acquired. Medical compromise can be due to a whole variety of factors, some of which are illustrated in Table 11.1. The term ‘immunocompromised’ refers specifically to congenital or acquired alterations of the immune system, which may render an individual susceptible to infection. The number of immunocompromised individuals is increasing rapidly, mostly because of the AIDS pandemic, but also through intervention therapy (drugs which deliberately modify the immune system). A good example of the latter is deliberate suppression of the immune system with drugs to prevent rejection during and following solid organ transplantation. The oral microflora in immunocompromised patients is changed either by colonization with exogenous microorganisms which are not normally found in the mouth, or by the occurrence of opportunistic infection. It used to be believed that any person who was immunocompromised had to be given prophylactic antibiotics to prevent infection after surgery. This is not necessary unless there is a proven degree of impairment of immune defences which renders them susceptible to infection. The extent to which an immunocompromised patient is susceptible to infection can be measured by a variety of blood tests to assess the function of their immune system. These include simple tests on the number and proportion of their immunological cells (predominantly white cells), their function, or their degree of abnormality. Only where there is a proven loss of functional protective immunity is there a necessity to give prophylactic antimicrobials before surgery (Ch. 8).

Table 11.1 Orofacial infections that may occur in medically compromised patients

Disorder Example Orofacial infection
Endocrine disorders Diabetes mellitus Oral fungal infections
Respiratory disorders Asthma Oral fungal infections
Neurological disorders Epilepsy Gingival hyperplasia and periodontal disease
Neoplastic disease Oral carcinoma Dental caries and mucositis following radiotherapy
Chronic infection Tuberculosis Oral tuberculosis
Immunological disorders HIV and AIDS Oral viral and fungal infections
Haematinic deficiencies Anaemia Angular cheilitis and oral fungal infections

The status of the teeth and oral soft tissues is often a reflection of systemic health. Thus, opportunistic orofacial infection may be the presenting initial feature of systemic disease. In this chapter, the types of orofacial infection that are seen in medically compromised patients as a result of the presence of underlying disease or as a result treatment will be considered.

Osteoradionecrosis

Cancer in the oral region is treated usually by surgery, radiotherapy, chemotherapy or a combination of all three. Radiotherapy destroys the rapidly dividing cancer cells, but it also destroys surrounding bone. This bone is highly susceptible to secondary radiation as it absorbs a great deal of energy. Bone is affected by radiation in three ways; there is a decrease in the number of cells (hypocellularity) and reduction in blood vessels (hypovascularity) and, as a consequence, less oxygen in the tissue (hypoxia). As the bone heals after irradiation, fibrous tissue is generated instead of bone, especially in the mandible. The effects of radiation therapy are not transitory and the hypovascularity increases with time. A simple operation on tissues which have been irradiated, such as a tooth extraction, can result in spontaneous death of the surrounding bone (necrosis). Death of the bone after irradiation can be progressive and is called osteoradionecrosis and has been associated with oral ulceration caused by ill-fitting dentures, scaling of the teeth, facial bone fractures and root canal therapy. In the past, the radiation therapy was not so highly focussed (collimated) on the malignant tissue and the surrounding normal structures were also often affected. In these conditions, the incidence of osteoradionecrosis in oral bone varied from 17–37%. With careful collimation, shielding of surrounding tissues, use of small but effective repeated radiation doses (fractionation), the incidence of osteoradionecrosis has been reduced to 2–5%.

Osteoradionecrosis is likely to arise due to a combination of radiation, trauma and infection. However, extensive animal studies support a view that the microorganisms are contaminants and cause secondary infection of pre-existing necrosis. Interestingly, molecular techniques applied to necrotic tissue obtained from cases of osteoradionecrosis have detected a predominantly anaerobic microflora, including Porphyromonas spp. and Prevotella spp.. Osteoradionecrosis is a difficult condition to treat despite the provision of an antibacterial agent, such as metronidazole or clindamycin, combined with surgery.

Pyostomatitis vegetans

This condition is associated with the presence of active inflammatory bowel disease, in particular, ulcerative colitis or Crohn’s disease. The oral mucosa is diffusely inflamed, with fissured ulcers separating papillary projections (Fig. 11.3). Histological examination reveals suprabasal separation of the epithelium with the formation of eosinophilic abscesses. The severity of pyostomatitis vegetans often mirrors the bowel disease activity. Interestingly, the provision of metronidazole can relieve oral symptoms. Healing occurs when the underlying inflammatory bowel disorder is brought under control.

Cancrum oris (noma, gangrenous stomatitis)

This is a severe form of necrotizing periodontal disease, and is seen occasionally in developing countries, in particular, sub-Saharan Africa (Ch. 6). The sufferer is characteristically less than 10 years of age, malnourished and has a history of a recent viral infection, such as measles (Ch. 10). The initial lesion spreads into the cheek, face and neck causing extensive tissue loss. Treatment is with a combination of antibiotics, such as benzylpenicillin with metronidazole, but each combination should include agents active against both Gram negative and Gram positive microorganisms.

Xerostomia

Xerostomia means literally dry mouth and can be caused by a variety of conditions or treatments (Table 11.2). One of the consequences of xerostomia is overgrowth of dental plaque, with acidogenic oral streptococci and lactobacilli predominating within the biofilm. This can induce a dramatic increase in dental caries if teeth are present. Xerostomia predisposes to the development of mucositis and opportunistic Candida infections of the oral mucosa.

Table 11.2 Causes of xerostomia

Drug therapy (in particular antidepressants)
Sjögren’s syndrome (immunological destruction of salivary tissues)
Damage to salivary glands following radiotherapy
Undiagnosed or poorly controlled diabetes
Dehydration
Congential absence of salivary glands

Jan 5, 2015 | Posted by in General Dentistry | Comments Off on 11: Oral implications of infection in compromised patients
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