Lecture 14: UTIs Flashcards
What is one of the most common reasons for visiting a primary care physician
A UTI
How many % of women have a UTI by the age of 30
50
Who are UTIs most common in
Young women (0.5-0.7 UTIs/person/year)
and postmenopausal women (0.07 UTIs/person/year_
How many % of women will experience a second episode within 6 months of their first UTI
25%
What is a bacteriuria
The presence of bacteria in urine, does not necessarily imply infection
What is an asymptomatic bacteriuria
The presence of bacteria in the urninary tract in the absence of symptoms
How is most common to have an asymptomatic bacteriuria
Elderly population (but this is also typically ignored and not treated)
When is asymptomatic bacteriuria treated
in pregnant women
in patients undergoing invasive procedures of the urinary tract
Is urine sterile, yes or no
yes
How is urine sterility maintained
Adequate urine volume
Free-flow from kidneys through urinary meatus/opening
Complete bladder emptying
Normal acidity of urine
peristaltic activity/muscle contractions of ureters (connect kidney to the urninary bladder)
Increased intra-vesicular pressure preventing reflux
In males how is urine sterility maintained
antibacterial effect of zinc in prostatic fluid
What are the 3 different factors that determine the classifications of UTIs
Location
Condition of the urniary tract or the patient
Evolution
What are the different locations that a UTI can happen in
Upper tract infection (pyelonephritis) ex. kidney
Lower tract infection (cystitis and urethritis)
What are the different conditions of the urinary tract or the patient for classification of UTIs
Uncomplicated and complicated
What are the different types of evolution that are important for the classification of UTIs
Acute
Chronic (symptoms persist over time)
Recurring (replace or reinfection)
What is cystitis
UTI presumed to be confined to the bladder
What are the 3 most common signs of cystitis
dysuria (pain on urination)
Urinary frequency
urinary urgency
What are other signs of cystitis
Supra-pubic pain
Hematuria (blood in urine)
Nocturia (peeing at night)
Bladder tenesmus (feeling like you need to poop even though your bladders are empty)
absence of vulvar or vagina discharge or irritation
What is acute urethritis cause by
By a sexually transmitter infection
Chlamydia trachomatis
Neisseria gonorrhoeae
What is Vulvitis caused by
This is inflammation of the vulva
caused by contact dermatitis, allergic reaction
Candida albicans, HSV infection
What is the most common type of UTI
cystitis
What is Vaginitis
Inflammation of the vagina
Caused by the bacterial vaginosis
What is pyelonephritis and what is it characterized with
clinical diagnosis imposes a more invasive infection
Upper tract infection
Inflammation of the kidney and renal pelvis is assumed to be present when patients have pain or tenderness involving the flank, together with other clinical or laboratory evidence of UTI
What are the systemic findings of Pyelonephritis
Fever, flank pain, nausea, chills, malaise headaches, etc
What is prostatitis
inflammation/inflammation of the prostate gland
may be acute or chronic
What is infrarenal abscess
Collection of pus in the kidney or in the soft tissue surrounding the kidney
What is another name for infrarenal abscesses
perinephric abscesses
Who is most likely to get an uncomplicated UTI
young non-pregnant women with normal genitourinary tract
Who is most likely to get a complicated UTI
Structurally or functionally abnormalities of the genitourinary tract
Pregnant women, elderly, men, and children
Chronic symptoms
Cormorbid illness (ex. diabetes) or immune-compromised
Upper tract disease (pyelonephritis)
What is a complicated infection in UTIs
Underlying abnormality that predisposes patient to UTI or makes UTI more difficult to treat effectively
What are the two types of recurrent UTI infections
Relapse
Re-infection
Relapse in UTI
Recurrent of infection by the SAME organism after discontinuation of treatment
Re-infection in UTI
Recurrent of infection by a DIFFERENT organism after discontinuation of treatment
Why is it important to know if a patient is having a relapse or re-infection with UTIs
Release: as this is with the same organism, maybe the patient wasn’t treated properly and their treatment needs to be altered
Re-infection: Maybe they have a structural abnormality or they are doing something to cause this
What is a pathogenesis
UTI usually due to patients own intestinal flora
Ascending (increasing) route of infection
How does pathogenesis occur
Its a type of UTI
Organisms enter the urniary tract in a retrograded (swim up) fashion via the urethra
What are complicated factors in pathogenesis
catheters, nephrostomy tubes, surgery, urniary stones, etc.
Allow organisms to easily enter and persist in urniary tract
Alter the typical spectrum of organisms (broaden the spectrum, typically only one organism)
May have multiple aetiologies
How does aging affect UTIs
Agging increases the likelihood of getting a UTI because..
Increased diabetes mellitus
Increased risk or urinary stasis
Impaired immune response
Incontienence
How does aging affect UTIs
Agging increases the likelihood of getting a UTI because..
Increased diabetes mellitus
Increased risk or urinary stasis
Impaired immune response
Incontinence (leaks urine by mistake)
Why are female likely to get UTIs
short urethra
Sexual intercourse
Contraceptives that alter the normal bacteria flora
Pregnancy (alters anatomy)
What type of Urinary tract obstructions make you more likely to get an UTI
tumor or calculi (kidney stones)
Strictures (narrowing in the intestines)
Why are males likely to get UTIs
prostatic hypertrophy (enlargement of the prostate gland) and anal intercourse
What the risk factors associated with UTIs
Aging
Female
Male
Urinary tract obstruction
Impaired bladder innervation
Hematogenous spread (through blood)
The majority of UTIs are ____microbial
mono
due to a single pathogen
What bacteria is responsible for 90% of UTIs
Enterobacteriaceae (family)
with Escherichia coli (E coli) being in this family and being the most commonly isolated pathogen in all UTIs
What is the structure of enterobacteriaceae
Gram negative bacilli
Facultatively anaerobia
Common intestinal flora
What are uro-pathgens
Basically the same as virulence factors that allow them to colonize and infect the urinary tract
What is the most important uro-pathogen in E. coli and how does it work
Adherence
P fimbria bind to the P blood group Ag present on uro-epithelal cells of 99% of the population
If there was no adherence the pathogen would come out when you pee because it wouldn’t be able to stick
What are uro-pathogens in E. coli
Adherence
Hemolysins, Colicin V: aid in resistance to complement dependent bactericidal effects of serum
K Antigen: associated with upper tract
Type 1 fimbria: interbacterial binding and biofilm formation
What are the classical UTI pathogens
Proteus
Morganella
Providencia
What is important about classical UTIs
The have the enzyme urease that breaks down urea and
increased urinary pH which leads to crystal formation/struvite stone formation, this then obstructs flow by providing a matrix (for organisms to form biofilms)
What are biofilms
Highly motile, producing fimbria for attachment
Making it hard for antibiotics to penetrate biofilms and
What is staphylococcus saprophytic in UTIs
it is coagulate -ve
typically associated with younger, sexually active females, but most common is still E. coli
1-5% of cystitis
How did staphylococcus saprophytic in UTIs used to be detected
using resistance to novobiocin
What is the effect of nosocomial UTIs
Health care associated infection, especially due to catheters, decreased the amount of E. coli but still is most prevalent bacteria
How is a UTI tested rapidly in office
urinalysis by dipstick testing
How does a urinalysis by dipstick testing work
It is primarily interested in the detection of nitrites and leukocytes produced by infection
Detection of nitrites is reasonably sensitive for gram-negative bacteria but highly specific (nitrites = gram negative bacteria is present. Nitrate–> Nitrate = gram negative )
Detection of leukocytes (white blood cells) is sensitive but not specific
Red blood cells in a urinalysis by dipstick testing
Red blood cell detection is not sensitive or specific
What is a semi-quantitative culture
Urine culture
What is a significant bacteriuria defined as
105 bacteria/mL (10^8 / L)
What are the two types of agar used for urine cultures
SBA/ MacConkey agar / Chromongenic agars
When might there be lower numbers in urine cultures
in children and in catheter collected specimens which may either be significant or due to contamination
What is the most common type of specimen collection of urine/UTI
Clean catch mid stream specimens
How does the clean catch mid stream specimens method of urine collection work
works by cleaning the urethra prior to collection,
first void urine allowed to pass urethra to clear urethra of contaminated material as the end of the urethra is not sterile
The midstream is collected in sterile container
Who are collection bags most commonly used for
Children that lack bladder control
But are often contaminated, so most meaningful result is a negative culture
What are indewlling catheters used for
As a urine collection method
Urine obatined by inserting needle into catheter or through diaphragm
Preferable to obtain specimen from new catheter rather than old Cather
What is supriapubic aspiration/straight catheters used
Urine collection method
It is quite invasive as the specimen is obtained directly from the bladder
Risk of contamination
How is urine transported
sent and processed by lab as quickly as possible
When transnsporting it you need to write the method or collection (because different cut offs) and the time/date of collection
Urine specimens not received by the lab in ____ hours must ____
1-2
be refrigerated
Urine not received within _____ or not _____ will be rejected by the lab due to ____
unless transported in a ___
24 hours
refrigerated
Contaminated bacteria can grow and lead to false positives
Boric acid tube
Should all patients with a suspected UTI be cultured
no
What is empiric therapy for UTIs
based on most probable pathogens
Lower vs upper tract infection
Local rates of resistance
Acute infection vs relapse/re-infection
What treatment is used for uncomplicated cystitis typically
Nitrofurantoin
Fosfomycin
What is used to treat pyelonephritis
b-lactam + aminoglycoside or ciprofloxacin/levofloxain
What other type of treatment is used for complicated infections
parenteral therapy and longer course of therapy up to 6 weeks
