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63 Cards in this Set
- Front
- Back
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Direct transmission
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Direct contact with microbial reservoir: From reservoir to next available host
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Indirect transmission
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Goes from reservoir to next available host via an intermidiate agent of transmission
Fomite Vector |
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Droplet
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travels < 1 meter; usually within personal bubble space
Contact transmission |
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Airborne
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travels > 1 meter
can travel long distances Vehicle - AIR |
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sometimes more growth after handwashing Why?
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Bar soaps become reservoirs
proper mechanical action during washing or drying was not used. did not wash long enough did not wash every surface did not dry properly |
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antibacterial soap for home use
not recomended |
does not work any better than regular soaps in reducing the # of "household" illnesses
Destroys normal flora contributes to antimicrobial resistance |
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Immunologic test
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any lab test that uses immunologic prinsciples
Humoral or cell-mediated immunity |
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Serologic test
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Antibodies are detected in serum by visualizing an Ag-Ab complex
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Serologic quantitative test
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How much antibody is present
performed by making serial dilutions of the patients serum row of tubes containing equal amounts of a saline diluent A measured amount of the patients serum is placed in the first tube and mixed well. then a measured portion is placed in the 2nd tube and mixed tube 1- 1:2 dilution tube 2- 1:4 dilution tube 3- 1:8 dilution Antigen in then added to each tube in a constant volume Tubes are examined for antigen-antibody reaction Last dilution of serum that show reactivity is reported as the serum titer if 1:16 is the last tube showing reactivity the serum titer is 16 |
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Purpose of Titer test
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To determine if an active infection is taking place
To check immune status |
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Rapid Antigen test
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Antigens are detected in a patient specimen by visualizing an Ag-Ab complex
Rapid Group A strep test Influenza A+B test Rotavirus test |
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Antigen detection
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The organism or specimen is mixed with a solution that extracts the antigen from the organisms' cell wall
It is then tested with antibodies unique to the specific organism If test incorporates antibody-coated latex particles, a positive reaction will produce agglutination (clumping) If test incorporates enzyme-linked antibodies (ELA) a positive test will produce a colored end product 100% sensative |
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Skin test
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immunologic test where antigens are injected under the epidermal layer of skin
Host is examined for a hypersensitivity reaciton Cell-mediated immunity PPD for tuberculosis |
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Sensitivity
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The ability of a test to detect minute quantities and still give a positive result
96% effective test 96 true positive 4 false negative |
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Specificity
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The ability of a test to detect ONLY what it 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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Quantitative test
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tells immune status
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Qualitative test
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Tells if someone has been exposed to organism
Lyme titer |
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Streptococci
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Gram positive cocci often arranged in chains
usually fastidious CATALASE NEGATIVE |
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Staphylococci
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Gram positive cocci
Found in environment and in the normal flora of skin, nares, and pharyngeal sufaces 3 Species S. epidermis S. saprophyticus S. aureus CATALASE POSITIVE |
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Streptococcus pneumoniae
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Alpha hemolytic streptococci
Common cause of pneumonia, meningitis, otitis media, and sinusitis |
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Streptococcus pyogenes
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Group A Strep
Beta hemolytic streptococci can cause acute pharyngitis (Strep throat), Otitis media, scarlet fever, Streptococcal Toxic Shock sydrome (STSS), Rheumatic Fever, Acute Glomerulonephritis and invasive skin infections May produce toxic substances that can affect the kidney (causing glomerulonephritis) the heart (causing acute rheumatic disease), and the skin scarlet fever rash |
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Streptococcus agalactiae
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Group B strep
Usually beta hemolytic streptococci Can colonize in female genital mucosa Potential infectious hazard for infants born of colonized mothers. Generalized infections or meningitis of the newborn caused by Group B streptococci is serious and often fatal |
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Enterococci
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Gram positive cocci that forms chains
Normal flora of intestinal tract can cause infective endocarditis (inflammation of the inside lining of the heart chambers and heart valves) Common cause of urinary tract and wound infections |
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VRE
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Vancomycin resistant enterococci
Very resistant to antimicrobials and difficult to treat. Patients are put into isolation to prevent spread of organism |
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S. pneumoniae
ID |
Gram positive diplococci
Catalase negative ALPHA HEMOLYSIS SF broth negative (tube stays purple and clear) OPTOCHIN SENSITIVE (P disc) |
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Alpha Streptococci
(Strep viridans) |
Gram positive cocci
Catalase negative ALPHA HEMOLYTIC SF negative (purple broth) OPTOCHIN RESISTANT (P disc) |
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S. pyogenes
Group A Strep |
Gram positive cocci
Catalase negative BETA HEMOLYTIC SF negative (purple broth) BACITRACIN SENSITIVE (A disc) |
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S. agalactiae
Group B Strep |
Gram positive cocci
Catalase negative Beta or Gamma hemolytic BACITRACIN RESISTANT (A disc) CAMP test POSITIVE (beta arrow on agur) SF negative (purple broth) |
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Enterococci
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Gram positive cocci
Alpha, beta or gamma Catalase negative SF broth POSITIVE (yellow, cloudy) BE POSITIVE (Slant tube turns black) then test to see if it is vancomycin resistant |
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Staphylococcus epidermidis
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normal flora of human surfaces tissues (skin and mucous membranes)
opportunistic indwelling catheters or cardiac surgery Virulent - biofilm (slime layer) |
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Staphylococcus saprophyticus
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causes Acute urinary tract infections in young women ages 16-25
NOT NORMAL FLORA |
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Staphylococcus aureus
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Normal flora
isolation if MRSA strain can produce toxins and harmful enzymes Enterotoxin=food poisoning Toxic shock syndrome can cause skin infections (pimples), furuncles (boils), carbuncles (hair folicles) and impetigo |
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S. aureus
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Gram positive cocci clusters
Catalase positive COAGULASE POSITIVE Oxacillin sensitive |
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MRSA
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Gram positive cocci clusters
Catalase positive COAGULASE POSITIVE oxacillin resistant |
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S. epidermidis
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Gram positive cocci clusters
usually gamma hemolytic Catalase Positive COAGULASE NEGATIVE NOVOBIOCIN SENSATIVE Typically oxacillin resistant |
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S. saprophyticus
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Gram positive cocci in clusters
Catalase positive COAGULASE NEGATIVE NOVOBIOCIN RESISTANT |
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Skin infection
Bacterial |
Staphylococcus aureus:
Bullous Impetigo Scalded Skin Syndrome TSS-Toxic shock syndrome Group A Strep: Erysipelas Impetigo Necrotizing Fasciitis Mycobacterium leprae |
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Skin infection
Fungus |
Ringworm
Sporotrichosis Chromomycosis Mycetoma Candidiasis Aspergillosis Zygomycosis |
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Skin infection
Viral |
Parvovirus B-19 virus (Erythema infectiosum, Fifth Disease)
Varicella Zoster virus (chicken pox and shingles) Variola Major virus (Small pox) Measles (Rubeola) Rubella (German measles) |
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Supportive media
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TSA
Non-fastidious microbes |
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Enriched media
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Provides exrta nutrients
Fastidious and non-fastidious microbes BAP, CHOC |
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Selective
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Allows the growth of one gram stain morphology while inhibiting another
PEA, MAC |
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Differential
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differentiates based on a specific characteristic 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 growth of Gram positive cocci Inhibits growth of Gram neg bacilli |
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CHOC
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Enriched
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MAC
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Selective- Encourages growth of Gram negative bacilli
inhibits growth of Gram positive cocci Differential-Lactose and non-lactose fermenting organisms |
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Cystitis
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Bladder infection
frequent painful urination usually caused by bacteria ascending urethra E. coli is most common cause |
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Pyelonephritis
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Infection of the kidneys
Signs and symptoms: Fever Flank pain symptoms of cystits may be caused by organisms ascending the ureters or hematogenous route (blood) |
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urethritis
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inflammation of urethra
Signs and symptoms: blood in urine pain during urination frequent urination urgent urination caused by: Chlamydia (bacteria) Gonorrhea (bacteria) Herpes simples (virus) other causes: injury allergy catheterization |
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urine specimen
Clean catch midstream |
to see what is causing a bladder infection
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urine specimen
SPA |
suprapubic aspirate
needle directly into bladder done if there is a blockage i.e. 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 the organisms that are inside the urethra |
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Incidence
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# of new cases diagnosed during a specific time period
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Prevalence
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Total # of cases, both new and old, at a given time. % 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 fatidious and fragile and require a portal of entry to cause infection |
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urine cultures quantitated
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1 lu (microliter of urine)
line down center of agur then zig zag across entire plate Incubate plate overnight @ 37 deg C Count each colony on plate Each colony represents 1 bacterium which form a cfu (colony forming unit) to convert to ml (milliliters) X by 1,000 (54 colonies + 54,000) or 5.4 X 10 to th 4th power cfu/ml |
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< 10 colonies
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skin contamination
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> 100 colonies
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Urinary tract infection
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between 10 and 100 colonies
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if several types of bacteria-may indicate a heavily contaminated specimen
1 type of colony could represent a true UTI in a very dilute urine specimen |
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urine sample
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Turbidity caused by bacteria, pus, and blood are indication of infection
Turbidity may also be caused by precipitating salts Many WBC's seen microscopically or detected by leukocyte esterase dipstick is an indication of infection Nitrates detected by dipstick is an indication of infection |
