E3- UTIs Flashcards
How are UTIs dx?
- Gram stain
- Culture (EMB/CLED)
- UA
- Prostate exam
- +/- imagaing
What type of culture media is selective for gram negative organisms?
EMB
What type of culture media is not selective for either gram positive or gram negative, but is used to determine the organisms ability to ferment lactose?
CLED
What type of culture medias should be used to dx UTIs?
EMB/CLED
What findings on UA microscopy are consistent with a UTI?
> 2 WBC or 15 bacteria
Who might require imaging to dx a UTI?
- Children
- Adults with recurrent infections
- Pts with blood in their urine
What are the 7 causative agents of UTIs?
- E. coili
- Klebsiella spp
- Proteus spp
- Enterococcus spp
- Staphylococcus saprophyticus
- Streptococcus agalactiae
- Pseudomonas aeruginosa
What are the gram negative causative agents of UTIs?
-E. coili
-Klebsiella spp
-Proteus spp
-Pseudomonas aeruginosa
“Every Kid Pees Pants”
What are the gram positive causative agents of UTIs?
-Enterococcus spp
-Staphylococcus saprophyticus
-Streptococcus agalactiae (GBS)
“Especially Slutty Girls”
What is the most common cause of UTIs?
E. coli
Is E. coli gram positive or gram negative? What shape?
Gram negative bacillus
What stain of E. coli causes UTIs?
UPEC strains
What is the lifecycle of E. coli?
- Access urinary tract following introduction of fecal contamination
- Use P fimbriae and Dr adhesions to bind to uroepithelial cells and erythrocytes
- Produce alpha and beta hemolysins
- Result in lysis of the uroepithelial cells and erythrocytes
UPEC have the ability to produce what?
K (capsular) antigen
Is Proteus gram positive or negative? What shape?
Gram negative bacillus
What species of Proteus is commonly community acquired?
Proteus mirabilis
What species of Proteus predominantly infects immunocompromised patients?
Proteus vulgaris
What is seen on agar with Proteus infections?
“Swarming” (except on CLED agar)
What structure do Proteus have that promote the attachment of bacteria to uroepithelial cells?
Fimbriae
What does Proteus produce that makes the urine more alkaline? How?
Urease
Hydrolyzes urea to ammonia
What can the increased pH caused by Proteus lead to?
Struvite stones
Is Straphlococcus saprophyticus gram positive/negative? What shape?
Gram positive cocci
Is Straphlococcus saprophyticus coagulase positive/negative?
Coagulase negative
What organism is associated with “honeymoon cystitis”
Straphlococcus saprophyticus
When do most cases Straphlococcus saprophyticus occur?
24 hours after sex
“honeymoon cystitis”
How can you differentiate Straphlococcus saprophyticus from other coagulase negative staphs?
Based on its novobiocin resistance
Is Streptococcus agalactiae gram positive/negative? What shape?
Gram positive cocci
What is seen on culture with Streptococcus agalactiae?
Gray/white colonies with narrow zone of beta-hemolysis
How do neonates get a Streptococcus agalactiae UTI?
Streptococcus agalactiae colonies the vaginia and can be passed during delivery
What are the virulence factors of Streptococcus agalactiae? (4)
- Capsular polysaccharide
- Hyaluronidase
- Collagenase
- Hemolysin
How is Streptococcus agalactiae dx?
- Detection of CAMP factor
- Definitive dx requires isolation from urine, blood, or CSF
