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77 Cards in this Set
- Front
- Back
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Direct Transmission define:
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Direct contact w/ microbial reservoir. Moves from reservoir to next available host.
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Indirect Transmission define:
Examples (2) |
Goes from reservoir to next available host via an intermediate agent (object) of transmission.
Examples: fomite, vector |
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Airborne
How far does the droplet travel? How big is the droplet involved? Contact or vehicle transmission? |
travel: >1 meter (long distance)
size: < 5 microns (dry and light - droplet nuclei) Vehicle (air) |
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Droplet
How far does the droplet travel? How big is the droplet involved? Contact or vehicle transmission? |
travel: < 1 meter (personal space)
size: > 5 microns (wet and heavy) Contact |
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Sometimes why is there more growth after washing hands?
5 Reasons |
1. Bar soap can become reservoirs
2. proper mechanical action during washing or drying was not used. 3. Did not wash long enough 4. Did not wash every surface 5. Did not was properly |
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Antibacterial soap is not recommended for house hold use. Why?
3 Reasons |
1. does not work any better than regular soaps in reducing the # of household illnesses
2. Destroys normal flora 3. Contributes to antimicrobial resistance |
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What is a fomite?
Examples |
A non-living entity
Ex: doorknobs, handles ect. |
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What is a reservoir?
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Local environment or host that supports the survival and multiplication of pathogenic microorganisms.
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2 safest proper hand drying techniques
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1. Air dryer, creates friction to lift off bacteria
2. Paper towel, wiping hands creates friction. |
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Worst way to properly dry hands
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Spinning towels. Bacteria collects on the overly used hand cloth.
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Immunologic test(s)
2 priciples |
Any lab test that uses immunological principles
Humoral or cell-mediated immunity |
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What are Viral Cultures?
Performed in: |
Require living cells to grow, often taken 7-10 days or longer.
Performed in specialty labs |
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Cultures
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grow the causative agent of bacterial infection. Easy to test and identify
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What are Fungal Cultures?
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Growth rate for these cultures varies on fungal causing agent
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What is a serologic test?
Examples (2) |
immunological test in which antibodies are detected in serum by visualizing Ag-Ab Complex
Examples- Lyme and Rubella titer. |
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Serologic testing:
Quantitative Whats is testing? How is it performed? |
Testing: How much antibody is present
Performed: Making serial dilutions of the patients serum, by a row of tubes containing equal amounts of saline diluent. |
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How is the testing of tubes done for quantitative testing?
Steps 1, 2 ect. Last step. |
1. A Measured amount of the patients serum is placed in the first test tube and mixed well.
2. Then a measured portion is placed in the 2nd tube and mixed. ECT: Tube 1 - 1:2 dilution Tube 2 - 1:4 dilution Tube 3 - 1:8 diltuion Last step: Antigen is then added to each tube in the constant volume |
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What is observed in the tubes after placing antigen?
(example) What does the test tube show? and what is it reported as? |
Tubes are examined for the antigen-antibody reactions.
The dilution of serum that show reactivity is reported as the serum titer. Example: if 1:16 shows reaction the serum titer is 16 |
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What is the purpose of titer test?
(2) |
To determine if an active infection is taking place
To check immune status |
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What is the Acute titer?
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Acute titer is collected which the patient has signs/symptoms of disease and the level becomes the baseline for comparison.
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What is the convalescent titer?
(exception) |
Convalescent titer is collected 3-6 weeks after the first
(does not mean necessarily the patient is in the convalescent stage of disease) |
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What test would be appropriate to help determine the stage of infection? (2)
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IgG and IgM
to tell if patient is in the acute stage of infection or if active infection is at a lower level |
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What is sera?
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Ser is plural form of serum, collected for a paired titer to determine if antibody response has occurred.
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What is four-fold increase?
Why is it important? |
A four-fol increase in titer means that there is at least 4 times as much antibody in the convalescent titer compare to the acute (baseline) titer
Its important because it is considered serologic evidence of a current active response to the micro org. being tested. |
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What is a Rapid Antigen Test?
Examples (3) |
A Rapid antigen test, tests which antigens are detected in a patients specimen by visualizing Ag-Ab complex
Examples: Rapid GAS test Influenza A + B test Rotavirus Test |
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Antigen Detection:
Sensitivity What is mixed and what happens? What is then added into test? If come back positive: 2 ways. |
100%
Testing the organism or specimen is mixed with a solution that extracts the antigen from the organisms cell walls. The solution is then tested with antibodies unique to the specific organism. If the test incorporates antibody-coated latex particles, a positive reaction will produce agglutination(clumping) If the test incorporates enzyme-linked antibodies (ELA) a positive test will produce a colored end product. |
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Antigen testing itself
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is 100% sensitive, its directly related to the amount of organism present in the collected specimen.
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What is a Skin Test?
Type of Immunity? Examples: 2 |
A test which antigens are injected under the epidermal layer of skin and host is examined for hypersensitivity reaction
Type of immunity: Cell-mediated immunity Examples: Allergy testing PPD for TB |
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Sensitivity:
What does it do? Test claiming Effectiveness: Outcomes (2) |
The ability of a test to detect minute quantities and still give positive result
96% effective test 96 true positive 4 false negative |
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Specificity:
What does it do? Test claiming effectiveness: Outcomes: 3 |
The ability of a test to detect only what is claims to measure
test claiming 96% effective 100 people without the disease 96 would test true negative 4 would test false positive |
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What does the results of a Rubella titer tell us?
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Rubella titer is quantitative and tells us whether individual is immune or not (immune status)
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What does the results of a Lyme titer tell us?
If positive: |
Lyme titer is qualitative and tells us the diagnostic of Lymes disease.
If positive: the individual has been expose to the Lyme organism. |
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Detection of microorganisms in specimen are: (test)
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Antigen Tests
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Detection of immune response in sera are: (test (2))
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titer or antibody test
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In class exercise:
What was fomite? What was reservoir? |
Fomite: the gloves used to shake hands
Reservoir: the tube of staph aureus |
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Quantitative test tells:
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tells immune status
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Qualitative test tells:
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If someone has been exposed to organism
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Why is a negative rapid GAS test followed w/ a 24 hour culture?
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Most tests lack sensitivity, meaning if you tested negative you could still have it.
A 24 hour culture is 100% sensitive so only 1 colony is needed for true testing if positive or negative. |
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What is + rapid GAS test detecting?
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Antigens
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Streptococci:
Stain/arrangement Fastidious/Non-Fastidious Catalase: (-/+) |
Gram Positive cocci/arranged in chains
Usually fastidious Catalase: Negative |
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Staphylococci:
Stain Found in: (3) Catalase:(-/+) |
Gram Positive Cocci
Found in: normal flora of skin, nares, and pharyngeal surfaces. Catalase: Positive |
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Streptococcus pneumoniae: Common cause of: 4 (disease)
Type of Pathogen |
Common cause of:
1. pneumoniae 2. meningitis 3. otitis media 4. sinusitis Pathogen: opportunistic, most common cause of bacterial pneumonia |
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Streptococcus pyogenes:
Can Cause: 5 Organism may produce toxin that cause: 4 Type of Organism: |
Can cause acute
pharyngitis otitis media scarlet fever invasive skin infections Organism may produce toxic substances that cause glomerulonephritis rheumatic disease rash in scarlet fever toxic shock syndrome Type of organism: pathogenic |
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Streptococcus Agalactiae:
Colonizes and potentially hazardous: Causes (2) in newborns: Often |
Colonizes in the female vagina, potentially hazardous to infants born.
Causes generalized infections or meningitis. Very serious and often fatal |
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Alpha Streptococci:
Called__ causes: Most dangerous when enters__ and causes: |
S. Mutans causes dental caries (cavities)
If enters blood stream can cause endocarditis by affecting the heart valves |
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Enterococci:
Stain/Arrangement: Type of organism: Can cause: Common causes: (2) If disease is VRE resistant: |
Stain/Arg: gram(+) cocci that forms chains
Type: Opportunistic Can cause infective endocaritis Commonly causes urinary tract and wound infections If VRE resistant, put into isolation to prevent spearding |
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VRE define
Treatment If resistant |
Vancomycin resistant to enterococci
Difficult to treat, very resistant to antimicrobials If resistant patients are put into isolation |
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Staphylococcus Aureus
Descrioption Found in __ of humans. Hospital caused infection Can produce and cause Can cause (4) skin infections |
Description: opaque, often golden-yellow pigment
Found in normal flora of humans Common cause of nosocomial infections Can produce toxins and harmful enzymes in the body and cause toxic shock syndrome Can cause skin infections (pimples), furuncles (boils), carbuncles (hair folicles) and impetigo |
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Staphylococcus epidermis
Description Where does is live Type of organism Many strains produce__which consists of__ Antibiotics: |
Description: opaque usually white
Lives on human surface tissues also mucous membranes Type of organism: opportunistic Many strains produce biofilm, which consists of secreted teic hoic acid and polysaccharides to produce slime layer. Antibiotic resistance in seen is 80-90% of these isolates in the hospital |
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Staphylococcus saprophyticus
Description: Can cause__ secondary only to__ Most often seen in Not common in Not a member of |
Description: opaque, white or yellow pigment
Can cause acute UTI secondary only to E. Coli Most often seen in females between 16-25 years old Not common in men until age 50 due to enlargement of prostate Not a member of normal flora |
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Supportive Media
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TSA
Non-fastidious |
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Enriched media
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Provides extra nutrients
Fastidious and non-fastidious BAP, CHOC |
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Selective
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Allows growth of one gram stain
PEA, MAC |
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Differential
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differentiates base on specific characteristics after colony grows on plate.
BAP- Hemolysis MAC- Lactose fermentation |
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BAP
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enriched
differential - hemolysis |
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TSA
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Supportive
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PEA
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Selective
Encourages gram + cocci Inhibits growth of gram - bacilli |
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CHOC
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Enriched
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MAC
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Selective
Encourages gram - bacilli Inhibits gram + cocci differential Lactose and non-lactose fermentation |
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Cystitis
sign common cause |
Bladder infection
painful urination E. coli most common cause |
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Pyelonephritis
signs/symptoms (3) caused by |
infection of kidneys
signs/sympt: fever flank pain painful urination caused by orgs. ascending the ureters or hematogenous route (blood) |
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urethritis
signs/symptoms (5) caused by (6) |
inflammation of urethra
Signs/sympt: blood in urine blood in urine pain during urination frequent urination urgent urination Caused by: Chlamydia (B) Gonorrhea (B) Herpes simples (V) OTHERS: allergy injury catheterization |
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urine specimen
Clean catch midstream |
to see what is causing a bladder infection
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urine specimen
Suprapubic aspiration (SPA) reason |
needle directly into the bladder
reason: being blocked ex kidney stone |
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urine specimen
first a.m. |
most concentrated specimen
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first voided specimen
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STI's
to catch organism insie urethra |
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Incidence
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# of new cases diagnosed during a specific time
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Prevalence
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Total # of cases, both new and old, at a given time
percent or population affected with a particular disease |
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Contracting a STI from a fomite
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theoretically possible but highly unlikely
organisms causing sti's are both fastidious and fragile |
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Alpha hemolytic
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partial hemolysis of rbc, creating green zone around coloy
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Beta hemolytic
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complete hemolysis of rbc, creating clear zone around colony
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Gamma hemolytic
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no change in media
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Urine cultures quantitative
Inoculating Colonies cfu conversion |
1 lu (microliter of urine)
Inoculated: line down middle, streak back and forth over line Colonies: Count the # of colonies on agar plate, each colony represents 1 bacterium cfu: colony forming unit to convert to ml (milliliters) # colonies X by 1,000 (54 colonies + 54,000) or 5.4 X 10 to the 4th power cfu/ml |
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< 10 colonies shows
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skin contamination
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>100 colonies shows
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Urinary tract infection
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Between 10-100 colonies indicates
1 type of colony |
Indicates that if there is several types of bacteria, could be heavily contaminated specimen
1 type of colony could represent a true UTI in a very dilute urine specimen |
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Urine Sample (specimen)
indications of infection (3) detected (2) |
Turbidity causes by bacteria, puss, and blood are indicators of infection
Detection of nitrates on dipstick and detection of leukocyte esterase in dipstick/many wbc's seen microscopically indicates infection. |
