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L8 IBSS 1503 M6
microorganisms indigenous to humans
37
Science
Professional
11/30/2011

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Term
Microorganisms have specialized ecological niches in and on the body. This is due to 5 reasons. What are they?
Definition
1. specific receptor sites on host cells

2. nutritional needs

3. presence or lack of certain inhibitory substances produced by host

4. competition of other flora and environmental conditions
Term
What are the three predominant skin flora?
Definition
1. coagulase-negative staphylococci
2. propioibacteria
3. dipththeroids
Term
Predominant flora of the mouth (4)
Definition
1. gram + streptococci especially a-hemolytic strep

2. Facultative anaerobes (ex. eikenella corrodens causes of bite wound infections)

3. Anaerobes
spirochetes -gingival crevices
porphyromas gingivalis - gingival crevices
prevotella intermedia

4. yeasts
Term
Predominant flora of the oropharynx, nasopharynx (4)
Definition
1. gram +, especially a-hemolytic streptococci

2. gram - cocci that resemble Neisseria meningitides

3. nontypeable Haemophilus influenzae (NTHi)

4. transient flora
Term
Transient flora of oropharynx and nasopharynx
Definition
1. Streptococcus pneumoniae (sinusitis, otitis, pneumonia)

2. Gram - rods

3. Haemophilus influenzae, type b

4. Neisseria meningitides (bacterial meningitis)

5. Strep pyogenes

6. Coagulase-positive Staphylococcus
Term
flora of esophagus and stomach:
Definition
few organisms, mostly from saliva. most are killed by acidity of stomach.
Term
flora of duodenum and jejunum:
Definition
sparse concentrations

ileum - organisms qualitatively similar to those in the lg intestine
Term
flora of colon: (4)
Definition
>100 species, mostly anaerobes

1. Bacteroids & Bifidobacterium - in colonic mucosal

2. Clostridium perfringens A &C

3. Coliforms - gram - rods, facultative anerobes. indicate fecal contamination in food

4. yeasts - Candida

Feces is 20% bacteria
NF of gut are stable after solid food diet is introduced. Only severe situations can alter NF changes in gut.
Term
flora of vagina and ectocerix:
(8)
Definition
mostly anaerobic

1. Lactobacillus - predominant, important in maintaining a low pH

2. Group B streptococci - Strep agalactiae, can be both NF and have pathogenic potential

3. Gardnerella vaginalis - bacterial vaginosis

4. Mobiluncus - bacterial vaginosis

5. Mycoplasma & Ureaplasma - can be sexually transmitted and passed to neonates.

6. Staph aureus - toxic shock syndrome

7. Candida - vaginitis

8. Veillonella - resembles Neisseria gonorrhea
Term
what portions of the vagina are normally sterile?
Definition
-distal portion of the endocervix
-uterus

cervical mucous plus prevents entry of microbes into the uterus
Term
In a normal immunocompetent person what is normally sterile (does not have NF)?
(7)
*KNOW
Definition
1. blood
2. spinal fluid
3. synovial fluid
4. bladder urine
5. lower respiratory tract
6. uterus
7. internal organs/tissues
Term
Discuss how NF can stimulate the innate immune response:
Definition
1. Lactobacilli in vaginal mucosa produce H2O2 that reacts w/ cel myeloperoxidase to produce HOCL- which inhibits/kills other bacteria.

2. Production of lactic acid by lactobacilli and propionic acid by propionibacteria inhibits bacterial growth in vagina and on skin
Term
Discuss how NF can stimulate the adaptive immune response:
Definition
1. NF can induce production of cross reacting Ab that can protect against pathogens. Ex. Ab induced by E. coli in gut protect against Haemophilus inflenzae

2. NF induced Ab are responsible for induction of isohemagluttinin (naturally occurring ABO blood group antibodies.
Term
List 3 ways that NF can prevent colonization by pathogenic organisms:
Definition
1. competing for receptor sites

2. competing for nutrients

3. producing substances which inhibit or kill pathogens (lactobacilli in vagina produce H2O2)
Term
What essential nutrients can be synthesized from NF?
Definition
Vit B and K

if pt is on broad spectrum antibiotics for a long time they can develope a nutritional deficiency
Term
Situations in which NF may become problematic:

(7)
Definition
1. damage to epi

2. presence of foreign body (catheters, prostheses)

3. transfer of bacteria to sites where they are not normally

4. suppression of immune system by drugs or radiation

5. impairment of host defenses due to infection

6. disruption of normal flora by antibiotics

7. unknown precipitating factor

8. unknown shift of normal flora in vagina

9. hospitalization or institutionalization
Term
What are the periodontogpathogens?
Definition
Porphyromonas gingivalis
Prevotella intermedia
Eubacterium

Gingivitis and perio caused by oral NF leading to tooth loss can be trigged by increase flow of nutrient rich, Ab containing GCF due to an inflammatory response to accumulation of dental plaque.
Term
How does hospitalization cause NF to become predominant?
Definition
1. NF of oropharynx and upper airways shift from gram + to gram -

2. skin increases colonization by enterococci and gram - bacteria

3. certain meds can slow peristalsis leading to sepsis

4. Prolong supine position, stomach hypoacidity can allow colonization of GI tract and oropharyngeal by lower GI flora. If aspirated can cause pneumonia

5. Catherization, intubation can cause nosocomial infections in urinary and respiratory tracts
Term
What are probiotics?
Definition
Use of living microorganisms to establish NF homeostasis w/ host. Prevents, treats, or cures some diseases.

Used in IBS, Crohns, food allergies.

Most contain mix of Lactobacillus and Bifodobacterium.

A great deal of fluctuation in the purity can exist.
Term
a-hemolytic strep

gram+ or gram - and where they are found
Definition
Gram + cocci in chains

Oropharynx

Cause serious disease when displaced from niche
Term
Bacteriodes
Definition
gram - anaerobic rods

intestine

serious infections if displaced
Term
Bifidobacterium
Definition
Gram + anaerobic branching rod

symbiotic relationship w/ human intestine
aids in digestion
inhibits growth of bacteria and yeast
used in probiotics
Term
Clostridium
Definition
gram + anaerobi rods

intestine

can cause food poisoning, pseudomembranous colitis
Term
Coagulase negative staphylococci
Definition
gram + cocci in clusters

skin flora and vagina
Term
Coagulase positive staphylococci
Definition
gram + cocci in clusters

nasal nares, skin, rectum, vagina

can cause skin and soft tissue infections and hospital acquired infections (nosocomial)
Term
Diphtheroids
Definition
gram + curved rods (chinese character arrangements)

skin

rarely cause nosocomial or infections in immunocompromised
Term
Eikenella corrodens
Definition
gram - pleiomorophic rods, facultatively anaerobic

oral flora

common cause of human bit wound infections
Term
Enterobacteriaceae
Definition
gram - rods

gut flora

causes sepsis, UTIs
Term
Haemophilus influenzae
Definition
gram - rods

oropharyngeal flora

may be pathogens

if capsule present can be serotyped (A, B, C...)

most NF are not capsulated (nontypeable H. influenzae)
Term
Lactobacillus
Definition
gram + rods

beneficial to GI and vagina
Term
Mycoplasma
Definition
no cell wall, no gram stain

pleiomorophic shape but tend to be flask shaped

ubiquitous in nature, colonizes
Term
Neisseria
Definition
gram - diplococci

colonize mucosal surfaces

N. gonorrhoeae and N Meningitidis are pathogens
Term
Oral spirochetes
Definition
not truly gram reactive, visualized on darkfield microscopy

oral flora

associated w/ perio disease
Term
Porphyromonas gingivalis
Definition
gram - anaerobic rod

oral flora

may cause perio
Term
Prevotella
Definition
gram - anaerobic rod

oral flora

may cause abscesses, perio
Term
Propionibacteria
Definition
gram + rod, obligate anaerobe

skin, specifically the pilosebaceous gland

causative agent of acne and other infections
Term
Yeasts
Definition
not bacteria but stain gram +

mucosal surfaces

opportunistic pathogens
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