Transcript Lab 8-urine culture

Urine Culture
Urine Gram Stain
Urine Culture Quantitation
Clean catch or catheterized urine
Plate = 1000 organisms/ml
Clean catch: >105 orgs/ml
Suprapubic urine
Any colony is significiant
Urine Cultures
1. Plates initially read at 18-24 hr
2. All specimens plated after NOON of
the previous day, hold another
overnight
3. Gram positives take longer to grow
Most Common Pathogens of
Human Urinary Tract
 Community
acquired
– E. coli is most frequent pathogen
isolated
– Klebsiella sp and other
Enterobacteriaceae
– Staphylococcus saprophyticus
 Hospital
acquired
– E. coli, Klebsiella, other
Enterobacteriaceae
– Pseudomonas aeruginosa
– Enterococci and Staphylococci
Abbreviated Identification
 E.
coli
– Non-swarming, spot indole pos, oxidase
neg
Lactose positive (MacConkey or eosin
methylene blue), PYR (pyrrolidonyl
arylamidase) test positive
2. API
1.
Abbreviated Identification
 Proteus
spp.
– Swarming growth
– Indole
 Negative:
P. mirabilis/penneri
– P. mirabilis: maltose neg, ornithine pos
– P. penneri: maltose pos, ornithine neg
 Positive:
P. vulgaris
Abbreviated Identification
 P.
aeruginosa
– Oxidase-positive bacillus
– Typical smell (grapes)
– Colony morphology P. aeruginosa:
metallic/pearlescent, rough, pigmented,
mucoid
– Indole-negative
Abbreviated Identification

CHROMagar Orientation
– Presumptive ID for some UTI pathogens
 E.
coli (dark rose to pink)
 Enterococci (turquoise blue)
 S. saprophyticus (light pink to rose)
 S. agalactiae (light blue-green to light blue)
 Proteus-Morganella-Providencia group (brown)
 Klebsiella-Enterobacter-Serratia group (dark blue)
– Issues and challenges
 All
except E. coli and enterococci require further ID
– Small E. coli colonies require spot indole
 Poor
growth of some gram-positive bacteria
 Nonselective– other pathogens may or may not
produce color change
Abbreviated Identification
 Enterococcus
spp.
– Cocci or coccobacilli in pairs and chains
– >1 mm colonies
– Non-hemolytic on SBA
– Catalase-negative
– PYR-positive
(pyrrolidonyl-a-naphthylamide
hydrolysis)
Abbreviated Identification
 S.
–
–
–
–
–
–
–
agalactiae (GBS)
Cocci in pairs and chains
Catalase-negative
Narrow zone of beta-hemolysis on SBA
Rapid hippurate hydrolysis test (beta strep only) OR
Test for CAMP factor (spot or O/N) OR
Typing by particle agglutination
R/O beta hemolytic Enterococcus (PYR+)
b-hem Enterococcus
Abbreviated Identification

Yeast
– Candida albicans
 Microscopy
required: oval, budding yeast
 Colonies <48 h old on blood-containing medium with
“feet” or mycelial projections
*CHROMagar
Abbreviated Identification

Candida CHROMagar
Why females has higher incidence
of UTI??
 Short
urethra
 Anus nearby urethra
 contraceptives
Now to the lab…