UTI Flashcards
Host defenses from UTI
- pH below 5.5
- Chemical content (high urea)
- Flushing mechanisms of urine
Symptoms of urethritis and cyctitis:
- Dysuria (painful urination), frequency and urgency.
- There can also be low back pain and abdominal pain or tenderness over the bladder area.
- Urine may be cloudy. 50% of cases present with hematuria.
- Positive urine culture
Symptoms of prostatitis
- Lower back pain and pain in perirectal area and testicles
- Can be accompanied by high fever, chills and symptoms of bacterial cystitis
- Positive urine culture
Symptoms of pylonephritis (kidney ascending UTI)
- Pain in the flanks of the body and fever above 38.3˚C.
- May be accompanied symptoms of cystitis.
- In more severe cases can present with diarrhea, vomiting and tachycardia.
- Positive urine culture.
- In 20-50% of pregnant women, the infection causes premature birth
UTI diagnosis:
-Based on symptoms
-examination of urine for evidence of bacteria or accompanying inflammation
-Requires the collection of a clean voided midstream urine sample
~90% of UTI are identified as pyuria= more than 10 wbc per cubic millimeter of urine
-The presence of at least one bacterium per microscopic oil-immersion field is an indication of infection (correlates to 100,000 CFU/ml)
-Can still have UTI with CFU <100,000
-Culture of causative agent from urine
-esterase (indicated WBC in urine) and nitrite (shows E. coli- reduce nitrate to nitrite) tests with dip stick
estase is for?
enzyme in WBC so when getting urine test this enzyme indicates presence of WBC in urine.
UTI - epidemiology/who gets and factors to geting:
- One of the most common infections in the United States
- 7 million cases of cystitis, 250,000 cases of pyelonephritis in otherwise healthy individuals in the US/year
- Ten times more common in women than men (shorter urethras colonized by fecal flora)
- Sexual intercourse increases risk
- Other predisposing factors: obstruction (prostate hyperplasia), kidney surgery, catheterization, GU malformation, diabetes and pregnancy
- Most common type of health care associated infection (usually catheter-UTI or CA-UTI)
community acquried UTI oranginsm most likely:
staphylococcus saprophyticus and E coli
hospital acquired UTI organism is most likely
klebsiella, enterobacter, serratia, pseudomonas aerugenosa, enterococcus, proteus*
E coli - organism info:
- gram negative rod
- rigid cell wall
- free living
- enteric rod
Enteric bacteria details:
- routinely found in the GI tract
- faculative anaerobes
- Gram -
- relatively hardy
- contain LPS
- belong to diverse taxonomic groups
- minor fraction of total microbial flora of GI tract
Enterobacteriaceae family- details:
- Largest, most heterogeneous collection of medically important gram-negative rods
- Ubiquitous, found worldwide in soil, water, vegetation
- Normal intestinal flora of most animals
- Grow rapidly, facultative anaerobes
- Ferment glucose, reduce nitrate, catalase positive, oxidase negative
- Serology based on O-polysaccharide antigens of LPS, K (capsular) antigens and H (flagellar antigens): Example: E. coli O157:H7
Enterobacteriaceae family - virulence factors;
- Endotoxin-responsible for many manifestations of infection
- Capsule - antiphagocytotic, inhibit complement
- Antigenic phase variation: K and H antigens are alternately expressed or not expressed (protects from antibodies)
- Type III secretion systems: Facilitate secretion of virulence factors into host cell
- Sequestration of growth factors: Iron chelating compounds
- Resistance to serum killing
- Antimicrobial resistance
Escherichia coli info
- Part of the normal flora of the colon in humans that infects the urethral area
- The difference in the degree of virulence of different strains is correlated with the acquisition of plasmids, integrated prophages and pathogenicity islands
- Has fimbriae or pili that are important for adherence to host mucosal surfaces
- Most ferment lactose (as opposed to Salmonella and Shigella)
- Important for differential diagnosis
msot common cause of UTI?
E. Coli - coontamination of urogenital tract with fecal flora
E coli virulence factors:
- Adhesins: bind to cells lining bladder and upper urinary tract
- Hemolysin: lyses erythrocytes and other cell types leading to induction of an inflammatory response
- Endotoxin: inflammation
- **-type I pili (attachment pili): bind to mannose residues commonly present on epithelial surfaces–> uroepithelial cells have sugar residues
second most common UTI pathogen?
stapylococci - coagulase negative –> found in fecal flora
