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Oral infections

As noted earlier, normal oral microbiota can cause dental and periodontal infections. However, there are number of other infections that can manifest in the oral cavity when other microbes are present.

Herpetic gingivostomatitis

As described in Viral Infections of the Skin and Eyes , infections by herpes simplex virus type 1 (HSV-1) frequently manifest as oral herpes , also called acute herpes labialis and characterized by cold sores on the lips, mouth, or gums. HSV-1 can also cause acute herpetic gingivostomatitis , a condition that results in ulcers of the mucous membranes inside the mouth ( [link] ). Herpetic gingivostomatitis is normally self-limiting except in immunocompromised patients. Like oral herpes, the infection is generally diagnosed through clinical examination, but cultures or biopsies may be obtained if other signs or symptoms suggest the possibility of a different causative agent. If treatment is needed, mouthwashes or antiviral medications such as acyclovir , famciclovir , or valacyclovir may be used.

a) photo of a cold sore (red bump) on the lip. B) bumps are present in the back of a person's mouth.
(a) This cold sore is caused by infection with herpes simplex virus type 1 (HSV-1). (b) HSV-1 can also cause acute herpetic gingivostomatitis. (credit b: modification of work by Klaus D. Peter)

Oral thrush

The yeast Candida is part of the normal human microbiota, but overgrowths, especially of Candida albicans , can lead to infections in several parts of the body. When Candida infection develops in the oral cavity, it is called oral thrush . Oral thrush is most common in infants because they do not yet have well developed immune systems and have not acquired the robust normal microbiota that keeps Candida in check in adults. Oral thrush is also common in immunodeficient patients and is a common infection in patients with AIDS.

Oral thrush is characterized by the appearance of white patches and pseudomembranes in the mouth ( [link] ) and can be associated with bleeding. The infection may be treated topically with nystatin or clotrimazole oral suspensions, although systemic treatment is sometimes needed. In serious cases, systemic azoles such as fluconazole or itraconazole (for strains resistant to fluconazole), may be used. Amphotericin B can also be used if the infection is severe or if the Candida species is azole-resistant.

Photo of white lumpy patches in the mouth.
Overgrowth of Candida in the mouth is called thrush. It often appears as white patches. (credit: modification of work by Centers for Disease Control and Prevention)

Mumps

The viral disease mumps is an infection of the parotid glands, the largest of the three pairs of salivary glands ( [link] ). The causative agent is mumps virus (MuV), a paramyxovirus with an envelope that has hemagglutinin and neuraminidase spikes. A fusion protein located on the surface of the envelope helps to fuse the viral envelope to the host cell plasma membrane.

Mumps virus is transmitted through respiratory droplets or through contact with contaminated saliva, making it quite contagious so that it can lead easily to epidemics. It causes fever, muscle pain, headache, pain with chewing, loss of appetite, fatigue, and weakness. There is swelling of the salivary glands and associated pain ( [link] ). The virus can enter the bloodstream ( viremia ), allowing it to spread to the organs and the central nervous system. The infection ranges from subclinical cases to cases with serious complications, such as encephalitis , meningitis , and deafness. Inflammation of the pancreas, testes, ovaries, and breasts may also occur and cause permanent damage to those organs; despite these complications, a mumps infection rarely cause sterility.

Mumps can be recognized based on clinical signs and symptoms, and a diagnosis can be confirmed with laboratory testing. The virus can be identified using culture or molecular techniques such as RT-PCR. Serologic tests are also available, especially enzyme immunoassays that detect antibodies. There is no specific treatment for mumps, so supportive therapies are used. The most effective way to avoid infection is through vaccination. Although mumps used to be a common childhood disease, it is now rare in the United States due to vaccination with the measles, mumps, and rubella (MMR) vaccine.

Photo of child with a very large swelling on one side of the neck.
This child shows the characteristic parotid swelling associated with mumps. (credit: modification of work by Centers for Disease Control and Prevention)
  • Compare and contrast the signs and symptoms of herpetic gingivostomatitis, oral thrush, and mumps.

Oral infections

Infections of the mouth and oral cavity can be caused by a variety of pathogens, including bacteria, viruses, and fungi. Many of these infections only affect the mouth, but some can spread and become systemic infections. [link] summarizes the main characteristics of common oral infections.

Table titled: Oral Infections. Columns: Disease, Pathogen, Signs and Symptoms, Transmission, Diagnostic Tests, Antimicrobial Drugs. Dental caries; Streptococcus mutans; Discoloration, softening, cavities in teeth; Non-transmissible; caused by bacteria of the normal oral microbiota; Visual examinations, X-rays Oral antiseptics (e.g., Listerine). Gingivitis and periodontitis; Porphyromonas, Streptococcus, Actinomyces; Inflammation and erosion of gums, bleeding, halitosis; erosion of cementum leading to tooth loss in advanced infections; Non-transmissible; caused by bacteria of the normal oral microbiota; Visual examination, X-rays, measuring pockets in gums; Tetracycline, doxycycline, macrolides or beta-lactams. Mixture of antibiotics may be given. Herpetic gingivostomatitis; Herpes simplex virus type 1 (HSV-1); Lesions in mucous membranes of mouth Contact with saliva or lesions of an infected person Culture or biopsy; Acyclovir, famcyclovir, valacyclovir. Mumps; Mumps virus (a paramyxovirus); Swelling of parotid glands, fever, headache, muscle pain, weakness, fatigue, loss of appetite, pain while chewing; in serious cases, encephalitis, meningitis, and inflammation of testes, ovaries, and breasts; Contact with saliva or respiratory droplets of an infected person; Virus culture or serologic tests for antibodies, enzyme immunoassay, RT-PCR; None for treatment; MMR vaccine for prevention. Oral thrush; Candida albicans, other Candida spp.;  White patches and pseudomembranes in mouth, may cause bleeding; Nontransmissible; caused by overgrowth of Candida spp. in the normal oral microbiota; primarily affects infants and the immunocompromised. Microscopic analysis of oral samples; Clotrimazole, nystatin, fluconazole, or itraconazole; amphotericin B in severe cases. Trench mouth (acute necrotizing ulcerative gingivitis); Prevotella intermedia Fusobacterium species, Treponema vincentii, others; Erosion of gums, ulcers, substantial pain with chewing, halitosis; Nontransmissible; caused by members of the normal oral microbiota; Visual examinations, X-rays; Amoxicillin, amoxicillin clavulanate, clindamycin, or doxycycline.

Key concepts and summary

  • Dental caries , tartar , and gingivitis are caused by overgrowth of oral bacteria, usually Streptococcus and Actinomyces species, as a result of insufficient dental hygiene.
  • Gingivitis can worsen, allowing Porphyromonas , Streptococcus , and Actinomyces species to spread and cause periodontitis . When Prevotella intermedia , Fusobacterium species, and Treponema vicentii are involved, it can lead to acute necrotizing ulcerative gingivitis .
  • The herpes simplex virus type 1 can cause lesions of the mouth and throat called herpetic gingivostomatitis.
  • Other infections of the mouth include oral thrush , a fungal infection caused by overgrowth of Candida yeast, and mumps , a viral infection of the salivary glands caused by the mumps virus, a paramyxovirus.

Fill in the blank

When plaque becomes heavy and hardened, it is called dental calculus or _________.

tartar

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Short answer

Why do sugary foods promote dental caries?

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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