L 93 UTI Flashcards
When in life do males have a higher incidence of UTI than females?
Only in first few months of life and is generally due to congenital abnormalities.
When in life do males and females begin to have an equal ratio of UTI’s?
Later in life after 50
Because males begin to have BPH which causes urinary stasis and leads to an increased risk of infection
What is the primary source of bacteria for UTI’s?
Fecal bacteria
This is partly why females have a higher incidence of UTI’s
What are the chances that a UTI is not ascending but somehow came from within the body?
There is a 5% chance that the infection is not ascending
What are some factors that predispose women to UTI’s?
Shorter urethra
New sexual partner and being sexually active
Certain contraceptive methods like diaphragms and others
Pregnancy: blocks ureter, progesterone decreases valve muscle tone, hormones decrease peristalsis causing stasis
Menses: lose normal flora causing increased risk of E. coli, S. saprophyticus infection
Postmenopausal: decreased estrogen changes vaginal flora, bladder and uterine prolapse causing stasis
What are some factors that predispose men to UTI’s?
Uncircumcised infants can have fecal contamination of the prepuce causing infection
New sex partner, anal sex
BPH
What is an uncomplicated UTI?
UTI in otherwise healthy individual that is not pregnant and an adult
Everyone else is complicated
What are the Enterobacteriacea?
These are the PESSKY Strains: Enterobacter Proteus Escherichia Shigella Salmonella Klebsiella Yersinia Citrobacter
What are the two most common causative agents for UTI’s?
E. coli: g(-)
Staph. saprophyticus: g(+)
Describe the fimbriae of E. coli and how they function as a virulence factor
E. coli has 2 kinds of fimbriae that act as adhesins and virulence factors:
1) Mannose-Sensitive or Type 1: bind to lower UT, bind mannose residues on proteins of the bladder, prescribing mannose may help eliminate these bacteria
2) P fimbria: assoc. with pyelonephritis (upper UT), bind P blood group antigens which are disaccharides found on surfaces of uroepithelial cells, they do not bind mannose
Patient is found to have Struvite crystals on catheter. What virulence factor is responsible, what is the mechanism of crystal formation, and what are the organisms potentially responsible?
Struvite crystals are formed when Mg and Ph precipitate out of urine that has a higher pH than normal. This happens when the enzyme urease is present which hydrolyzes urea into ammonia. The organisms that have this enzyme are”
Staph. saprophyticus
Proteus mirabilis
Stones can also form in the kidney and ureter from this.
What are some of the less common causative agents for UTI’s?
Enterococcus faecalis Staph epidermidis Proteus mirabilis Klebsiella pneumoniae Citrobacter
Patient has an upper UTI and bacteria are found to be bound to P blood group antigens on the epithelial cells which is allowing a prolonged course of the infection. What is the virulence factor and the likely agent?
P fimbriae bind to the P blood group antigens on uroepithelial cells
This is a virulence factor of E. coli
What virulence factor allows the swarming of bacteria and which bacteria are known to swarm?
Flagella allow the motility of bacteria which is needed for swarming to occur. The most talked about bac. in class that swarms is Proteus, but E. coli and Citrobacter also have flagella that allow for motility.
Which virulence factor may help protect from phagocytosis and which agents have it?
Capsular K Antigen helps protect from phagocytosis and is only found on g(-) enterobacteriacea like E. coli
If S. aureus or Salmonella are found to be the causative agents for the UTI, what route of infection is now more likely?
The majority of UTI’s are caused by ascending infections. However, it is possible to have a descending infection and these tend to be caused by S. aureus and Salmonella, but can also be from M. tuberculosis, and Candida
Patient has dysuria, pyuria, hesitancy, and increased frequency of urine. They are found to be infected with a common STD. No flank pain or suprapubic tenderness or feverWhat is the likely diagnosis?
Urethritis is the likely diagnosis
This is a localized inflammation of the urethra and is not necessarily a UTI involving the bladder or kidneys
Can be concurrent with cystitis in females and prostatitis in males.
Often caused by STD’s
Patient presents with bacteriuria, pyuria, suprapubic tenderness and hematuria. No flank pain or fever. What is the likely diagnosis?
Cystitis or lower UTI
This is localized to the bladder
Patient presents with fever, malaise, N/V, and headache. Flank pain and CVA tenderness are present. WBC casts are seen in the urine. What is the likely diagnosis?
Pyelonephritis
This is an infection of the kidneys
Systemic Sx and casts are indicative of upper UTI
What levels of bacteria are needed in the urine to diagnose a UTI?
Greater than 10^5 CFU/mL except for with S. aureus and Salmonella where any amount is enough for a diagnosis
Hematuria is common in UTI’s, but what similar conditions do not have blood in the urine?
Urethritis
Vaginitis
What agar is used to select for g(-) bacteria?
MacConkey Agar
What is the purpose of CLED agar?
CLED agar is used because it lacks the necessary agents for Proteus to swarm
What does a Kirby-Bauer test tell you?
tells susceptibility
