Upper Alimentary System Infections

ADVANCE ORGANIZER

The alimentary tract is a major route of entry for pathogenic organisms. The upper alimentary includes the organs from the mouth down to the stomach and includes the salivary glands and esophagus too. Our food and water contain a large variety of organisms that find their way into the body by this route. A properly functioning stomach with its acids is an extremely efficient barrier to many microorganisms.

ANATOMY AND PHYSIOLOGY

Degradation of foods begins in the mouth with the grinding action of the teeth and mixing with saliva. Saliva contains amylase which begins the degradation of starch and protects the teeth. In the stomach one cell type produces hydrochloric acid, another enzymes like pepsin which degrades proteins under acid conditions. and a third cell type makes mucus.

READING ASSIGNMENT: CHAPTER 24

ANATOMY and PHYSIOLOGY

The structure of teeth, their poistion in the mouth and the necessary activity of eathing make this a very dangerous place.

NORMAL FLORA

Bacteria that live in the mouth colonize dependent upon their ability to attach to teeth, tongue, cheeks, other bacteria.
Dental plaque consists of ENORMOUS quantities of bacteria of various species attached to teeth or each other. Streptococci and actinomycetes initiate plaque formation. Teeth allow for anaerobic bacteria.

INFECTIONS CAUSED BY ORAL BACTERIA

Dental caries are mainly caused by Streptococcus mutans and relatives. The calcium phosphate of the tooth is penetrated by acid production in response to dietary sucrose by the plaque. The pathogenesis is aided by the ability of S. mutans to form intracellular insoluble polysaccharides.
Periodontal disease is a major cause of tooth loss in older adults. This is dental plaque growing at the gingival crevice. The bacterial products and the host’s response to them cause loosening of the teeth.
Acute necrotizing ulcerative gingivitis [AKA: ANUG, trenchmouth, and “Vincent’s angina”] is caused by Fusobacterium ( spindle shaped Gram negative anaerobes) and Treponema (spirochetes). It causes acute infection in the gingival tissue resulting in necrosis with pain, bleeding and fever.
Complications of dental work: Endocarditis in patients with abnormal heart valves is commonly due to oral bacteria such as Viridans streptococci. Entry of these bacteria into the blood stream frequently occurs with dental procedures. Properly timed antibacterial treatment can prevent the disease when an abnormal heart structure is known.
Esophageal infections caused by the yeast, Candida albicans are seen in immunocompromised individuals.
Stomach infections by Helicobacter pylori [an acid tolerant, urease-producing curved rod with sheathed flagella]predisposes the stomach and upper duodenum to peptic ulcers and may be a factor in stomach cancer. Even though the H. pylori is susceptible to antimicrobial medications in vitro the treatment is difficult. One problem is the bugs can handle the acid but our treatments often cannot handle it! Effective treatment does prevent reoccurrence.

VIRAL DISEASES OF THE MOUTH AND SALIVARY GLANDS

Herpes simplex [also known as cold sores or fever blisters can occur on the mouth and surrounding skin. Latent infections are characteristic of Herpes viruses. The virus persists inside sensory nerve ganglia in a non-infectious form that can become infectious and produce active disease. This is triggered by various stresses (sunburn, times of high emotion, exams). The virus can be present even in the absence of symptoms and infect other people. Before dentists starting treating us in wet suits, this was an occupational hazard often resulting in herpetic fingers. The virus is an enveloped DNA virus.
Esophageal infections caused by the Herpes Simplex virus are seen in immunocompromised individuals.
Mumps virus is an enveloped RNA virus that infects initially spreads through the saliva, infects the upper respiratory system, then spreads to the parotid glands, meninges, testicles and other body tissues. The disease is much more severe in people beyond puberty. There is a live vaccine which can protect against mumps.