UTIs Flashcards
What are the categories of UTIs?
Upper tract
Lower tract
What are the upper urinary tract infections?
Pylenephritis
What are the symptoms of pylenephritis?
Flank pain and fever (> 38.3C)
What are the lower urinary tract infections?
Cystitis
Urethritis
Prostatitis
What are the symptoms of cystitis?
Dysuria, frequency, urgency, suprapubic pain, hematauria.
Incontinence in children and elderly
What are the symptoms of Urethritis?
Dysuria
What are the symptoms of prostatitis?
pain in lower back,
perirectal area and testicles, fever
What is Asymptomatic Bacteruria?
Significant bacteria in the urine in the absence of symptoms.
Typically no treatment unless pregnant woman.
What are the entry points for infections?
Hematogeneous: Enter renal cortex from blood. Downstream infections
Ascending: Enter through urethra and ascend to upper tract. Urosepsis.
Which type of infections are more common and why?
Ascending
because of colonization of skin and mucosal surface next to the urethra meatus
What are the most common pathogen to cause a UTI from the blood? What are the minor ones? Where are the pathogens found if they are found in urine?
most common-
Staphylococcus aureus
Candida albicans (systemic infection)
Least common Mycobacterium tuberculosis Salmonella spp. Brucella spp. Enterococcus faecalis
When does candida albicans cause a systemic infection?
When does it cause a ascending infection?
when it is a deep infection like endocarditis
It causes a mucocutaneous ascending infection when using something like catheters
Where do most ascending UTIs begin?
Bacteria usually come from a person’s intestinal microbiome.
Bacteria colonize from perianum or vaginal introitus.
Who get the most UTIs? Men or women? Why?
Who accounts for the most UTIs in men?
UTIs less common in men
Longer urethral length
Less frequent colonization around urethra
Antibacterial substances in prostatic fluid
Who accounts for the most UTIs in men?
Most cases in males
Infants
Elderly
Anatomic abnormalities (prostatic hyperplasia)
For others, risk factors:
Anal intercourse
Lack of circumcision
Why do some bacteria become pathogens?
Some have virulence factors that enable them to colonize the urinary tract.
Some have help from mechanical introduction.
What are pathogens of Ascending UTIs?
Facultative gram negative rods (Eneterobacteriaceae), Enterococcus and
skin Staphylococci
UPEC specialized urinary pathogen
Uropathogenic E. coli
What are uncomplicated UTIs?
Uncomplicated
acute cystitis or pyelonephritis in nonpregnant outpatient women without anatomic abnormalities or instrumentation of the urinary tract. These infections rarely progress to severe disease.
What are complicated UTIs
Complicated
Occur when functional, metabolic, or anatomic conditions exist that increase the risk of treatment failure or serious outcomes. These conditions include obstruction, stones, pregnancy, diabetes, neurogenic bladders, renal insufficiency, immunosuppression, male gender, and hospitalized/healthcare associated settings.
How are UTIs caused?
Sexual intercourse
Hygiene: children
Catheters
Anatomical/functional abnormalities
Flow—-Bacterial adhesion
Age and gender dependent
What are the biggest factors of UTI infections?
age and gender
mostly women get UTIs
younger and older men get UTIs
What are the gram negative enterics that cause UTI?
UPEC (uropathogenic E. coli) (most important)
Klebsiella spp.
Proteus spp. (Proteus mirabilis)
Enterobacter sp.
What are the Gram positive Cocci that cause UTI?
Staphylococcus saprophyticus
Enterococcus sp.
What are the general characteristics of Gram negative enterics (enterobacteriacaceae)?
Gram negative rods Facultative Oxidase negative Catalase positive Nitrate Reductase Positive
What are specific characteristics of E. COLI?
E. Coli- most common pathogen (UPEC)
What are specific characteristics of Proteus mirabilis?
Motile (swarmer), common catheter introduced pathogen.
Urease positive: stones
Only gram negative enteric lactose negative
What are specific characteristics of Enterobacter?
Opportunistic , antibiotic resistant
What are specific characteristics of Klebsiella pnuemoniae?
Mucoid Colonies due to capsule.
Common catheter acquired pathogen. (Nosocomial Pneumonia)
What are the KEE lactose fermenting gram negative rods?
Klebsiella,
Enterobacter sp.,
Escherichia
What are the slow fermenting gram negative rods?
Citrobacter
Serratia
Others
What are the lactose negative?
Pseudomonas (oxidase positive)
proteus
What are the virulence factors of Proteus?
Highly mobile
Urease positive= produces stones
Which pathogens cause infectious stones?
usually proteus
Klebsiella as well
How are infectious stones formed?
Urease breaks Urea to
NH3 + CO2
Alkalization of urine, Ammonia irritates
Alkalization -> Precipitation of phosphate and magnesium MgNH4PO4 (struvite) and apatite (Ca10(PO4)).
What are the gram positive cocci?
Staphylococcus saprophyticus
Enterococcus
What are the characteristics of staph Saprophyliticus?
Coagulase negative
Catalase +
Nitrate Reductase Negative
Resistant to novobiocin
What are the characteristics of enterococcus?
Catalase -
Alpha or gamma hemolytic
Nitrate Reductase Negative
What are host defenses against infection?
- Urine flow flushes bacteria2.
- Prevention of bacterial adherence
3. Antimicrobial factors: Lactoferrin, Antimicrobial peptides (defensins and cathelicidins (cathe-li-seye’-din) common)
- Exfoliation: promoted by the pathogen
- Chemokines and cytokines:
- Neutrophils
- Prevention of upper tract infection
What is the the Common Pilus?
What does it have for attachment?
What does it attach to?
Type I Pilus (also called common pilus—is common)
FimH: Adhesin
Attach to α-methyl-D-mannoside glycoprotein receptors on cells P Pilus (PAP-pyelonephritis associated pilus)
What is the Pilus associated with UPEC?
What does it attach to?
Where is it expressed?
P Pilus (PAP-pyelonephritis associated pilus)-required for UPEC to invade Upper urinary tract
P pili bind to P blood group antigen which contains a D-galactose-D-galactose residue (gal-gal receptor)
Expressed on bladder, ureters, kidney epithelium (as well as erythrocytes
Expression genetically variable
What are the UPEC virulence?
Pili: Type 1 and P pili Capsule Exfoliation QuiescentModulating innate immunity: cytokine production (SisA, SisB) Strain dependent
What is the function of the capsule on UPEC?
Extracellular: protection from opsonization, phagocytosis, complement mediated killing
Intracellular: Biofilm formation which is necessary for proliferation and aids in persistence
What is the function of the Quescent state?
May reactivate infection (recurrent infections)
What is the function of Modulating innate immunity: cytokine production (SisA, SisB)?
Decreases neutrophil migration and inflammation
What is strain dependent?
Influences symptom severity
Influences progression to pyelonephritis
What are the virulence factors UPEC use to enter the body?
Type I Pili
P Pili
Invades cells: Type III Secretion system
What are the virulence factors UPEC use to survive and reproduce in the body?
Modulating cytokine production SisA and SisB
Capsule: immune evasion and biofilm formation
Quiescent state
Hemolysin and Siderophores: (aerobactin) acquiring iron and nutrients
What are the virulence factors UPEC use to exit in the body?
Hemolysin A: exfoliation
What specimen is used for diagnosis?
urine
What is looked for when testing urine for UTI?
Bacteria (Significant Bacteriuria)
WBC (Pyuria)
What is the problem with urine specimens?
How is a clean urine sample collected?
Problem: Contaminants (fecal and vaginal flora/WBC)
pure specimen is collected by:
Clean catch urine (antiseptic cleaning and midstream collection, fast processing)
Catheter, suprapubic aspiration
Quantitation
What are the diagnostic tolls used to detect UTIs?
Urine Dipstick
Urinalysis
Quantification
culture
What is detected with Urine dipstick?
Nitrites (Action of Nitrate reductase-gram negative rods)
Leukocyte esterase (enzyme of neutrophils)
What is detected with urinalysis?
Microscopy
Visualize bacteria and WBC’s, urinary casts
Hemocytometer
What number is used for patients to diagnose UTI?
10^5
Which agar to detected Gram negatives? what do they detect?
Gram negatives: MacConkey agar or eosin-methylene blue
Detect
Lactose fermentation
Inhibits gram positive growth
Which agar to detected Gram positives? what do they detect?
Gram positives: blood agar, cysteine lactose electrolyte deficient agar
