Bacterial infections Flashcards
List the 5 conditions that make the oral cavity ideal for bacterial growth
- Warm
- Moist environment
- Provides surfaces for attachment and growth
- Constant supply of nutrients in the form of saliva
- Dietary intake provides times of excess nutrient supply
State the difference between prokaryotes and eukaryotes
- Prokaryotes are organisms made up of cells that lack a cell nucleus or any membrane-encased organelles. Have circular DNA and no mitochondria. BACTERIA ARE PROKARYOTES
- Eukaryotes are organisms made up of cells that possess a membrane-bound nucleus that holds genetic materials well as membrane-bound organelles.
Explain the difference between gram positive bacteria and gram-negative bacteria
- Gram positive bacteria have penicillin binding proteins and a peptidoglycan cell wall
- Gram negative bacteria don’t have such a thick layer
What is selective toxicity
• Selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host.
Briefly describe amoxicillin and how it works
- Penicillin, the first antibiotic discovered
- Class=β-lactams (penicillins, cephalosporins ,monobactams, and carbapenems)
- Beta-lactams act by binding to penicillin-binding proteins that inhibit a process called transpeptidation (cross-linking process in cell wall synthesis), leading to activation of autolytic enzymes and lysis of the bacterial cell wall. Bactericidal=killing.
- Therefore, amoxicillin mainly targets gram positive aerobic organisms, specifically streptococci
Describe the mechanism of action of clavulanic acid
- Bacteria produce beta-lactamase enzymes which inactivate beta-lactam. This provides resistance to the bacterium
- The clavulanic acid is designed to overwhelm all β-lactamase enzymes (“Suicide agent”), and effectively serve as an antagonist so that the amoxicillin is not affected by the β-lactamase enzymes. Therefore it has a broader spectrum.
Describe what type of bacteria that metronidazole targets and how it works
- Anaerobic bacterial infections and facultative anaerobic microorganisms
- It works by inhibiting protein synthesis by interacting with DNA and causing a loss of helical DNA structure and strand breakage causing cell death. Bactericidal.
- Helps with periodontitis, ANUG and pericoronitis
- Can also treat Clostridium difficile
What is Waldeyer’s ring?
- This is known as the ring of oral defences
- Tonsils are masses of lymphoid tissue that produce defensive cells known as lymphocytes
- The ring acts as a first line of defence against microbes that enters the body via the nasal and oral routes
Describe the process of biofilm formation
- Biofilms are defined as matrix-enclosed bacterial populations adherent to each other and/or to surfaces or interfaces
- Polymicrobial biofilms contain two or more bacterial species that are important for the persistence and proliferation of participating microbes in the environment
- Change in environmental conditions leads to changes in the bacterial species in the biofilm, which may result in more pathogenic species becoming dominant. For example, caries and increased sugar intake.
State the most common type of bacteria available in gingivitis (3)
- Reversible inflammation of only the gingiva
- S+S: redness, hypertrophy, and bleeding.
Examples
• Gram-positive cocci
• Gram-negative bacilli
• Spirochaetes (gram-negative, motile, spiral bacteria, aerobic and anaerobic)
State the most common type of bacteria present in periodontitis, ANUG and pericoronitis
- Chronic inflammation of supporting structures of teeth -> destruction of connective tissue attachment to the tooth, alveolar bone resorption, and tooth loss
- Gram negative bacterias such as porphyromonas gingivalis (Gram-negative, rod-shaped, anaerobic) are present in all diseases
- Hence, metronidazole is used over amoxicillin for tx
Describe how endodontic infections are treated
Usually consist of anaerobic bacteria, so metronidazole
Explain contiguous spread
- There is increasing evidence that the oral cavity is relatively porous to oral bacteria
- For example chronic periodontitis patients can have bacterial DNA or viable oral bacteria dispersed throughout their bodies in atherosclerotic plaques or the placenta
- Many oral bacteria have been shown to be able to colonize and survive, if not thrive, once in the vascular system.
Describe the bacteria present in Ludwig’s angina and subdural abscess
- Rapidly evolving infection with bilateral involvement of sublingual and submandibular spaces requiring SURGICAL EMERGENCY –>FATAL
- Patients cannot breathe
- Usually polymicrobial (Streptococcus, Peptostreptococcus, Fusobacterium, Bacteroides, Actinomyces) so broad spectrum antibiotics
Describe the bacteria fusobacterium nucleatum
- Anaerobic gram negative bacterium that is very adherent
- Can invade epithelial and endothelial cells
- Thrives at 37 degrees
