Pathogen-Host Interactions Flashcards
Alterations of the Normal Flora - Genital Tract
- Altered vaginal flora (lactobacillus spp.) can lead to colonization by pathogens/overgrowth
- This leads to inflammation of the epithelium
- “Clue cells” under microscopy because they provide evidence of this
Clinical Manifestations of Altered Immune Flora
- Example
- Risk factors
- Associated with
C. difficile
- Leading cause of antibiotic-associated diarrhea
- Associated with changes in the GI flora
- Risk factors include
- Antibiotics
- PPIs
- Being in hospital
Associated with
- Ulcerative colitis
- Can lead to death or in some cases colectomy
Dysbiosis Factors
- Definition
- Examples
- Disturbed biota
- Antibiotics
- PPIs
- Appendectomy
- Surgery
- Chemotherapy
Non-pathogen
- Definition + Example
- Generally don’t cause disease except in very RARE cases
Eg Lactobacillus
Normal Flora
- Function
- Key aspect
- Ecological niches include…
- Part of us, the microbiota PROTECTS the body
- Certain organisms live in certain sites
Ecological niches include
- Mouth
- Nose
- Genital Tract
- GI tract
- Any route of entry/exit
All have bacteria that reside in these ecological niches
Normal Flora - BELT RULE
Above the belt - GRAM POSITIVES
Below the belt - GRAM NEGATIVES
Normal Flora - GI Tract
- Types
- Function
Depends on the site:
UPPER - Facultative anaerobes (both)
LOWER - Anaerobes
- Few Gram positives in the GI tract
Often used to digest food that the body’s GI tract cannot itself
Normal Flora - GU Tract
- Bladder?
- Genital Tract: Male vs Female
- Bladder does not tend to have a lot of bacteria
Male
- Not well established
- Mostly skin flora, which can cause inflammation in the male tract
Female
- Lactobacillus etc etc probably the only thing you’ll remember from this class in 3 years
Normal Flora - Problem with Hospitals
- In the hospital, patients are usually supine. This allows organisms to migrate up and down the body as there is no force acting against them (gravity)
- Tend to find gram negatives in the respiratory tract etc
Normal Flora - Respiratory Tract
- Types
- What changes the oral flora? Why?
- How are samples collected?
- Colonized by 10e9 bacteria/ml saliva
- Staphs, streps, some anaerobes
- Oral flora changes dramatically with TEETH
- Crevices of the teeth breed anaerobes which produce the bad breath
- Lungs are typically sterile, but samples can be taken from sputum
Normal Flora - Skin
- Type of bacteria
- Potential pathogens
- Generally colonized by GRAM POSITIVE bacteria
- Bacilli (Corynebacteria)
- Cocci (Staphylococcus)
- Organisms that can cause infection colonize the skin including pathogens like
- Staph aureus (coag pos)
- Coag neg staph predominate
Normal Flora/Microbiota
- Organisms that are typically found at a body site, may cause disease in another site
Pathogen
- Definition + Examples
Always causes disease
- Eg Neisseria gonorrhoea, ebola
Perturbing the Flora
- GI example
- Proton pump inhibitors can also disturb the gut flora by increasing the pH, reducing the capacity of the stomach acid to neutralize C. Diff
Perturbing the Normal Flora
- How and why
- Example
- Normal flora provides a level of protection from potential pathogens taking hold
- If the biota is ‘messed with’ by taking antibiotics, there is an increased risk of getting other bacterial infections
- C. Diff is the leading cause of antibiotic-associated diarrhea
- C. Diff produces toxins that can lead to significant disease in the colon (colitis) and even death
- Likewise, disturbances in the genital tract flora can lead to vaginitis
Potential Pathogen
- Does not always lead to disease
- Needs to happen at the right place and the right time
Eg Escherichia Coli
Virulence Factors
- Definition + Example
- Factors that help the organism cause disease or avoid immune response
Eg toxin production, capsule
