Lecture 4: Normal Flora Flashcards
Normal vs. transient flora?
Normal Flora: Organisms regularly found at any anatomical site
Transient Flora: Inhabit for relatively short period of time
True or False: You can be a carrier of transient flora and, as such, spread it to others
True
- many pathogens are transient flora
Anatomic distribution is determined by ______, which is the specific adherence between host’s receptor and microorganism’s ligand/adhesion
tissue specificity
Organ or tissue _____ reflects the ability of a given pathogen to infect a specific organ or sets of organs.
tropism
Which five environmental conditions shape the micro-environment of the anatomical site
pH
O2 tension
competition
inhibitory factors
substrate availability
___ is the key for maintaining Natural Flora in a good relationship with the host
Homeostasis
List a few host-specific factors that contribute to the composition of one’s natural flora:
1) Gender
2) Lifestyle
3) Genetics
4) Nutrients/Diet
5) Age
6) Health
True or False: Different natural flora at the SAME anatomical site in different people could have different effects and outcome
True
Which five sites of the human body are normally sterile?
(Hint: BLUCS)
- Uterus + internal organs
- Synovial fluid
- CSF
- Blood
- Lower respiratory tract
True or False: One of the benefits of normal flora is that it can stimulate the innate immune system, without stimulating the adaptive immune system
False - one of the benefits of normal flora is that it can stimulate BOTH innate and adaptive immune system
Lactobacilli in the vaginal mucosa produce ___, which reacts with the host cell myeloperoxidase to make ____, which inhibits or kills other bacteria
H2O2; HOCl- (hypochlorous acid)
Note: this is an example of NF stimulating innate immune system
Production of ___ acid by lactobacilli and ___ acid by proprionibacteria inhibits bacterial growth in vagina and on skin, respectively
lactic acid; propionic acid
Normal flora (NF) can induce the production of _____ antibodies, which can be protective against pathogens.
A. cross-reacting
B. several
C. AFB
A. cross-reacting
- this is an ex. of NF stimulating adaptive immune response
One example of NF stimulating adaptive immune response is: antibodies induced by the capsular polysaccharide of a given strain of E. coli found in the gut protects against infection with ________
H. influenzae
Which gut microbe induces a protective antibody against H. Infuenzae, type b capsule?
E. coli
True or False: Transient flora-induced antibodies are thought to be responsible for induction of isohemagluttinin (ABO blood groups)
False - NF-induced antibodies are thought to be responsible for induction of isohemagluttinin
What are three ways that NF prevent colonization by pathogenic organisms?
1) Occupy and compete for receptor sites on host cells
2) Complete with pathogens for limited nutrients
3) Make substances that are inhibitory or cidal to pathogens (e.g lactobacilli in vagina makes H2O2)
Which two nutrients (that are essential for the host) are made by the natural flora?
Vit B complex and Vit K
True or False: If a patient is on a broad spectrum abx for extended period, they may develop nutritional deficiency
True
How does hospitalization (e.g debilitation) change the NF of the oropharynx and upper air ways?
Shifts from Gram (+) to Gram (-) bacteria
How does hospitalization (e.g debilitation) change the NF of the skin?
Skin becomes more colonized by enterococci and enteric Gram (-) rods
True or False: Certain meds can SPEED UP peristalsis and, thereby, increase transition of gut flora across normal intestinal epithelial barriers, which can lead to sepsis
False - certain meds can SLOW peristalsis and, thereby, INCREASE transition of gut flora across normal intestinal epithelial barriers, which can lead to sepsis
Which three conditions can allow retrograde colonization of the upper GI tract and oropharyngel cavity by lower GI flora?
Note: If aspirated, can cause pneumonia
1) Immobile
2) Prolonged supine position
3) Hypoacidic stomach
Catherizations in urinary tract and intubation in respiratory tract can lead to ____ infections
nosocomial
Use of ____ can change balance of natural flora. For instance, organisms that were present in small numbers prior to abx could emerge as DOMINANT membrane of community and initiate infectious disease (super infection)
antibiotics
Overgrowth of toxin-producing strains of C.diff in colon can result in antibiotic-associated _____ ____
pseudomembranous colitis
Alterations in oral or vaginal flora lead to increased susceptibility to which two conditions?
1) Oral thrush
2) Vagina candidiasis
True or False: Immune compromises related to medical intervention, neoplasia, or infection allow for overgrowth of NF or new colonization with different flora
(note: either can be causes of opportunistic or nosocomial infections)
True
___: use of living microoragnisms to establish or re-establish NF homeostasis with human host, therefore, preventing, treating, or curing some infectious diseases
Probiotics
Which four disorder have probiotics been shown to be effective at treating?
1) Chronic/recurrent C dif
2) IBS
3) Crohn’s
4) Food allergies
True or False: Probiotics prevent side effects of abx tx and reduce chances of developing necrotizing enterocolitis in the neonatal ICU
True
What are three other uses of probiotics?
1) Reduce crying and sx in colic babies
2) Reduce eczema in infants
3) Help prevent cold and flu-like sx
Probiotics may contain a mix of which two beneficial bacteria?
Bifidobacterium and Lactobacillus
____: when both microbe and host benefit
____: when microbe benefits but host is not harmed
___: when microbe benefits and host suffers
Mutualism
Commensalism
Parasitism
Which type of parasitism occurs when normal flora becomes opportunist, typically when virulence is low?
A. Endogenous
B. Exogenous
A. Endogenous
True or False: An exogenous pathogen, which is not part of the normal flora, can cause a “classical infectious disease” and damages the healthy host
True
What is an example of an exogenous infection that can be considered an opportunistic infection, since it does NOT cause infection in immunocompetent people, but only becomes pathogen to immunocompromised or immunosuppressed people?
Pneumocystis pneumonia in people with cancer, HIV/AIDS
____: a microbial life form that is a harmful symbiont. The etiological agent of an infectious disease
A. Opportunistic pathogen
B. Frank pathogen
C. Pathogen
D. Non-pathogen
C. Pathogen
____: a pathogen that essentially always causes infection/disease in specific host
A. Opportunistic pathogen
B. Frank pathogen
C. Pathogen
D. Non-pathogen
B. Frank pathogen
___: infect or cause disease ONLY in compromised host (e.g those who are immune-suppressed, malnourished, have cancer)
A. Opportunistic pathogen
B. Frank pathogen
C. Pathogen
D. Non-pathogen
A. Opportunistic pathogen
True or False: Lactobacillus is an example of a non-pathogen (essentially never causes disease, even if host is severely compromised)
True
True or False: Pathogenicity and Virulence are essentially interchangeable terms that describe the degree to which a pathogen causes disease
True
Microbes pathogenicity (ability to cause disease) is described in terms of their ____(degree of pathogenicity)
virulence
The ____ factors (determinants of virulence) of a pathogen are any of the genetic, biochemical, or structural features that enable it to produce disease in a host
virulence
True or False: Pathogenicity varies from host to host, even in the same host species, and varies from pathogen to pathogen, even in the same species
True
