Microbiology-Oral, Esophagus & Stomach Infections Flashcards
What pathogens have adapted to overcome the natural defense of secretory IgA in the saliva?
Neisseria gonorrhoeae, strep pneumoniae and Hib all release proteases that destroy IgA.
Which streptococcus species are found in our normal oral flora?
Alpha-hemolytic (green partial hemolysis). This group includes strep pneumoniae and strep viridans.
What bacteria are included in the strep viridans group?
Strep with no defined Lancefield carbohydrate antigen on its surface. (mutans, mitts, sanguinis, etc.)
A patient comes to see you with many dental caries. Analysis of the bacteria in her mouth shows over-colinization of a normal flora that also exists in the vaginal and GI tract. What is the bug?
Gram-positive lactobacilli.
What is bacteria’s role in development of periodontitis?
It must be present, but is not sufficient to cause disease. Typical periodontitis happens when the ratio of anaerobes : aerobes is 1000:1.
What systemic problems can be caused by periodontitis?
Diabetes, Cardiovascular disease and adverse pregnancy outcomes.
Name 7 common oral pathogens
Staph, strep pyogenes (beta hemolytic), HSV, HPV, Coxsackievirus, Candida and many anaerobes.
Over-colonization of strep pyogenes can cause what condition in the throat? The skin?
Throat: pharyngitis Skin: scarlet fever, impetigo and cellulitis
What organism likely caused the lesions shown below?
Staph. Coagulase negative (mucosistis) and positive (aureus) staph causes stomatitis (colonization and ulcerations in the oral cavity)
What virus can cause these types of oral lesions?
HSV-1. Rarely HSV-2 can cause these lesions during oral sex.
What virus can cause these types of infections?
Coxsackie A virus, a picornavirus, is responsible for the herpangina seen in hand, foot and mouth disease.
What virus is responsible for the oral lesions shown below?
HPV 16 & 18 are responsible for these verrucous lesions. Note that these are the most common STI.
Which of the images below is pathogenic?
The hyphal form (right) is the form in which candida has ability to invade tissue and cause oral thrush.
What microbes can be responsible for esophagitis?
HSV, CMV, HPV and Candida. Note that these types of infections are typically found in immunocompromised individuals.
What microbes can cause gastritis?
1) Gram negative, urease positive, microaerophilic H. pylori. CMV and HSV can also cause gastritis.
50% of the world is colonized with H. pylori in their stomach. What percentage of people will go on to develop symptoms?
Of that 50%, 20% will go on to develop clinical symptoms to include: gastritis, adenocarcinoma, ulcers and MALT lymphoma.
What percentage of gastric cancers are associated with H. pylori? MALT lymphoma?
70-90% of gastric cancers. 90% of MALT lymphoma
How does H. pylori survive in the acidic stomach?
Urease. It catalyses urea to ammonia and CO2, which neutralizes the environment.
What toxins released by H. pylori contribute to its pathogenicity?
VacA activates mitochondria apoptosis signals and inhibits T-cell activation. CagA is an oncoprotein because it changes many cellular signaling pathways.
Diagnosing H. pylori infection
Clo test (culture after biopsy, shown below), radioactive breath test, biopsy, stain (Wurthin-Starry shown below), serum antibodies, fecal antibodies.
Treating H. pylori
Triple therapy (Amoxicillin, Clarithromycin + PPI)
Why not treat everybody with triple therapy?
It may be a protective normal flora and getting rid of it may cause esophageal cancer, active Tb and asthma.
