Oral microbiology

46 Oral microbiology




Questions


image Give two clinical examples of systemic infections caused by oral bacteria

image What is the pathogenesis of dental decay?

Oral microbiology has been placed at the end of Section 3 as it encompasses many of the areas discussed above.


The oral cavity harbors a number of microorganisms, which form the normal human oral microflora (e.g. viridans streptococci, anaerobic bacteria such as Fusobaterium spp, coagulase-negative staphylococci, Moraxella, Neisseria, Candida spp., herpesviruses). Most of the time bacteria, fungi and viruses live in a fine balance together without causing disease. Some people are asymptomatic carriers of potential pathogens such as Staphylococcus aureus or Streptococcus pneumoniae without causing harm. Oral disease can occur if the microbial flora or the host defences change. This may be as a result of hormonal changes, poor dental hygiene, immunosupression (e.g. HIV), stress or use of broad-spectrum antibiotics. There are also a number of systemic infectious diseases that manifest in the oral cavity (Table 3.46.1).


Table 3.46.1 SYSTEMIC INFECTIOUS DISEASE WITH ORAL MANIFESTATION







































Infection Oral manifestation
Scarlet fever (Streptococcus pyrogenes) ‘Strawberry tongue’ (white tongue with red papillae)
Syphilis (Treponema pallidum)  
Primary infection Painless, small nodules and ulcers
Secondary infection Shallow, ‘snail-track’ ulcers
Tertiary infection ‘Gumma’, painless, punched out ulcers
Congenital Hutchinson’s teeth (peg shaped teeth, notch in upper incisors)
Valley fever (fungal, Coccidioides immitis) Oral ulcers
Hand, food and mouth disease (coxsackie virus) Pharyngeal ulcers
Chicken pox (varicella zoster virus) Mucosal vesicles and ulcers
HIV Gingivitis
Measles (prodrome) Koplik’s spots (red spots in buccal mucosa)


Dental plaques and caries


Teeth have a hard protective layer of enamel. Food can collect in pits and cervices of the teeth, encouraging bacterial colonization and growth, which initiates the development of dental plaque. Within the plaque, bacteria form primitive communication systems (biofilms) where they are protected from the host response and the effect of antimicrobial agents (e.g. antibiotics, disinfectants) (Fig. 3.46.1).


image

Fig. 3.46.1 Dental plaques and biofilms.

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Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Oral microbiology
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