LO7, 7.1-7.5 Flashcards
upper vs lower urinary conssts of what
upper kidney and ureter
lower bladder and urethra
urine is always consdered sterile above
urethra
UTIs are dependant on factors such as:
- Age
- Sex (male vs. female)
- Hormonal change
- Diabetes
- Renal failure
- Neurological and structural abnormalities
most common gram negative bcsillus causing UTI
Escherichia coli
most common Gram positive coccus causing UTI)
Enterococcus sp.
7.2
what are the used preservative that is used to ship urine
boric acid, sodium formate or glycerol preservative in urine transport containers
7.3: Culture urinary tract specimens
what are callibrated loops and their use
urine spec are inoculated using a calibrated loop that have an exact volume
routine: 1 uL
sterule: 10 uL
used for a quantitative technique for culturing urine
The following is the calibrated loop method of culturing
- The sample is mixed by swirling and then the lid is removed.
- The loop is inserted vertically into the urine in the container and then removed (check for
bubbles). If the loop is not inserted vertically, the volume of urine picked up may be too
large and subsequent colony counts will be erroneously high. - The loop is then touched to the center of the agar plate and spread back and forth in a line
across the diameter of the plate. - The loop is drawn back and forth across the entire surface of the plate, going through the
original streak line several times
The plate media that are most often used for culturing urine are 4
BA, CLED, MAC, chromogenic
incubated at 35-37
7.4 : how to get CFU/ L
if in the 1uL you have 4 colonies then in a liter it should equal to = 4 x 10^6
ratio it out
first lab Learning Step 7.5: Identify the clinically significant bacteria:
Streptococcus sp. and Enterococcus sp.
2 genera and 8 species
Streptococcus
Enterococcus
Streptococcus pyogenes (Group A Streptococcus)
Streptococcus agalactiae (Group B Streptococcus)
Group C Streptococcus
Group D Streptococcus - Enterococcus sp.
- Non-Enterococcus
Group F Streptococcus
Group G Streptococcus
Viridans Streptococcus Group
Streptococcus pneumoniae (Learning Outcome 8, Learning Step 8.2)
The identification of β hemolytic streptococci is based on detection of specific
carbohydrate or “C” antigens in the cell wall.
Streptococcaceae: commone characteristiscs
-Gram positive cocci in pairs and/or chains
- Grey (sometimes grey-white) on BA
- catalase negative
- *facultative anaerobes
- *mesophiles
- require enriched media for growth (e.g. 5% sheep blood)
- genus Streptococcus is divided on the basis of the hemolysis reaction on blood agar (∝, ß, ϒ)
BA: small grey or grey-white, translucent; alpha-, beta-, or gamma-hemolytic
CLED: can be LF or NLF
MAC: no growth
PEA: small grey or grey-white
which specific test sis used to increse specification
PYR
Streptococcus pyogenes (βH)
Latex Group “A”
PYR – positive
Always considered a pathogen
Can be colonized in URT, skin and anal mucosa but not considered NF
Spread by direct contact or droplet
Has many virulence factors (toxins, hemolysins)
Localized Group A infections:
Acute pharyngitis (strep throat)
Skin infections (impetigo,
erysipelas)
Note: rarely seen in UTI
Streptococcal Pyrogenic Exotoxin causes:
Scarlet fever
Streptococcal TSS (toxic shock syndrome)
Systemic Group A infection travels to deeper tissues (necrotizing fasciitis)
POST-STREPTOCOCCAL DISEASES
Toxin production can cause secondary disease (sequelae) from localized infection:
Rheumatic Fever:
* Following respiratory infection
* May be mediated by antibodies against Group A that react with heart tissue
* Fever, carditis, subcutaneous nodules, polyarthritis
Acute glomerulonephritis
* Following respiratory or cutaneous infection
* Mediated by antigen-antibody complexes that deposit in the glomeruli
* Edema, hypertension, hematuria, proteinuria
2 hemolosys: Streptolysin S and O?
S is beta hemolysis and oxygen stable*, Inactivated by acid from
fermentation of glucose (use a low-carb BA)
O is mainly in Group A, needs to be incubated anaerobically*/ oxygen liable : AB would indicate infection
STREPTOCOCCUS AGALACTIAE
NF of female GT and lower GIT (sometimes also URT)
Can cause UTI
Transferred to baby in utero or during birth (leading cause of neonatal
sepsis)
Post-partum pelvic abscess and septic shock
GROUPS C, F, AND G STREPTOCOCCUS
NF of skin, nasopharynx, GIT, and GT
Not commonly found in UTI but significant in other types of infections
ENTEROCOCCUS SP./ Group D
Group D Streptococcus is divided into Enterococcus sp. and non-Enterococcus sp.
Enterococcus sp. can be gamma or alpha hemolytic
NF of the lower GIT and female GT
Most common Gram positive cause of UTI
Prominent cause of nosocomial infections: bacteremia, UTI, abdominal, pelvic and
wound infections
VRE – vancomycin-resistant Enterococcus sp.
NON-ENTEROCOCCAL GROUP D STREPTOCOCCUS SP
Usually considered normal flora
Not considered a cause of UTI
VIRIDANS GROUP STREPTOCOCCUS
NF of human oral cavity, GIT, female GT
Opportunistic, low virulence
Infections usually from endogenous strains getting access to normally sterile sites
like teeth during surgery
