Normal Flora or Pathogen?/Antimicrobials Flashcards
What three interactions can define the relationships of humans and their bacteria?
Commensalism, Mutualism, Parasitism
What is commensalism?
One benefits, other gets neither benefit nor harm
How might we benefit from commensal bacteria?
They compete with harmful bacteria
Important examples of mutualism in gut bacteria
Regulation of pro-antiinflammatory T-cell switch
Loss of certain bac associated with Crohn’s
Interactions with hormones
Alteration in microbiota of URT associated with…
Asthma
Significance of resident flora?
Very unique for each individual body part
Name for organisms that are not normally pathogenic, but can cause disease under special circumstances?
Opporutnistic/Pathobiont
Three special circumstances that pathobionts may play into?
Immunocompromised individuals
Accidental entry
Inflammation
Why is skin hard to colonize?
low pH
high NaCl
Lysozyme
Three primary bacterial organisms associated with the skin.
Staph Epidermis
Aerobic Corynebacterium
Propionibacterium acnes (in oily spots)
What part of the skin colonizes G-
Oily parts
What part of the epidermis has a substantially different microbial community from the others? Why?
Labia minora
Acidic conditions let lactobacilis take over
Three primary bacterium of the nasopharynx?
Proprionibacterium Staph epidermis (and sometimes aureus) Diptheroids (chinese characters)
Four opportunistic bacteria associated with nasopharynx?
Viridans streptococci
Streptococcus pneumoniae
Nisseria meningitidis
Hemophilus influenzae
Bacteria at the base of dental plaques
streptococcus
Four most important resident bacteria of the mouth and oropharynx?
alpha-hemolytic Strep (including mutans)
Staph epidermis (and aureus)
Pasteurellaceae
Actinomyces israelii
Most important bacteria of the stomach?
helicobacter pylori
Most important bacteria of the duodenum?
Lactobacillis
Most important bacteria of jejuno-ileum?
Enterobacteriaceae
G- Anerobes (Bacteroides)
Most important bacteria of the colon?
Bacteroides
Three gut enterotypes important for establishment of digestive health?
Bacteroides
Prevotella
Ruminococcus
What bacteria is more prevalent in high fat diets? high fiber diets?
fat – Bacteroides
Fiber – Prevotella
Relationship of bacteria to gut flora
They don’t directly contact eachother, or inflammation will occur.
Most common bacteria of the vagina
Lactobacillis
Bacteriodes
Prevotella
Changes in vaginal pH over the life cycle?
Acidic at birth
neutral till puberty, then acidic again
Most common bacteria of conjunctiva?
Staph/Strep
Hemophilus
diptheroids
List Six Sterile Areas
Lungs beyond trachea Internal organs (minus digestive tract) Fluids (Blood, Lymph, Semen) CNS Ear beyond Eardrum Fetus
Difference between viral and bacterial latency
In bacterial latency, organism is still present, but in lower numbers
Three types of adhesion factors involved in virulence factors.
Pili/Fimbriae
Adhesins
Capsules
Intracellular invasion/colonization factors
Streptokinase - dissolves blood clots
Hyaluronidase - Hydrolyzes connective tissues
Neurominidase - Degrades sialic acid glue
Collagenase - Destroys tissue
Two types of intraceullular invasion/colonization factors
Uptake by non-professional phagocytes
Uptake by professional phagocytes
How do non-professional phagocytes work?
Secreted effectors (T3-6) - cause membrane ruffles
Internalin polymerizes actin to allow comet tails
Ipas and Opas – promote engulfment
Five prevalent ways bacteria deal with phagocytes
Avoid Them Kill Them Prevent Lysosomal fusion with phagosome Break out of phagolysozome Resistance to lysozomal enzymes
What are endotoxin and exotoxin made of?
Endotoxin – Lipid A of LPS
Exotoxin – Protein, often A-B type
How do superantigens work?
Link T cells to macrophages that may not be displaying antigen. Leads to runaway inflammatory response.
What are PAI?
Collections of genes for virulence factors in one chromosomal location
How do we identify different bacteria locations?
Identify disease agents/reservoirs
Prevalence/Incidence Graphs - Surveillance
Culture/Diagnostic Sequencing
Difference between a prevalence and incidence graph?
Prevalence – TOTAL active cases in a population
Incidence – NEW cases in a given time period
Difference between epidemic and endemic?
Epidemic – sudden spike in incidence
Endemic – Continued high prevalence or repeated recrudescence
Why should you take caution diagnosing with diagnostic sequencing?
Watch for antibiotics
Could be normal flora for patient or hospital.
What does bacteriostatic mean?
Inhibits the growth of bacteria
What does a MIC test evaluate?
The minimum effective dose of an antibiotic in broth
What happens in a kirby bauer test?
Paper disc is soaked in antibiotics and placed on a plate of bacteria
Better version of a Kirby Bauer test?
E test in which you can read MIC from a strip
Which heat is more effective, wet or dry?
Wet
Other than heat, what are some other significant methods utilized in sterilization?
Radiation – UV damages any present DNA
Gas – Ethylene oxide causes alkylation of nucleic acids
Filtration – Size exclusion through 0.2 uM pore
Most common sterilization method?
Autoclave + Ethylene Oxide
Why must one worry about filtration?
Flexible forms/L-forms of bacteria and small, slow growing cells may get through
Doesn’t filter out viruses
What do high-level chemical disinfectants do?
Kills everything, even spores
What do Intermediate chemical disinfectants do?
Allow spores and some naked viruses to survive
What do low-level disinfectants do?
Allow spores, mycobacterium, some pseudomonas, and naked viruses
Two prevalent forms of disinfection?
Alcohol
Aldehyde
How do alcohols work against?
Dissolve lipids, denature proteins, dry out cells
How do aldehydes work against bacteria?
Crosslink or alkylate proteins
What do phenolics do?
Denature proteins, dissolve membranes.
Pros and cons of phenolics
Useful at high concentration
Irritants
Common phenolics? Particularly useful against?
Lysol, hexachlorophene
Staph and Strep
How do biguanides work? Where are they most commonly used? What specific type is used in that capacity?
Damage to Cell Membranes
Chlorhexidine is used in surgical swabs/dressings
Two commonly used halogens?
Iodine and Chlorine
How does iodine work?
Interferes with protein folding
Used as surgical scrub
Common – water soluble form – betadine
How does chlorine work?
Oxidizing agent (NaClO)
How do cationic detergents work?
Solubilize cell membranes
Cationic detergents must not be mixed with…
Anionic detergents
How do heavy metals work?
Derivatize -SH groups
Block Disulfide bonds
Example of the use of heavy metals in antibiotic treatment?
AgNO3 as prophylactic in newborn eyes
Ag-impregnated catheter tubing
