Micro 2.1

what is the one of the most common bacterial infections?

UTIs

-cystitis and pyelonephritis

what is the most common presentation of UTIs?

hematuria, dysuria, increased urinary frequency

how is a UTI diagnosis made?

via symptoms, urinalysis, and urine culture in inpatient and symptoms and urinalysis in outpatient

what are the clinical schemes for classifying UTIs?

single vs recurrent episode and complicated vs uncomplicated

what is a single episode UTI?

UTI occurs once

what is a recurrent episode of UTI?

UTIs occur repeatedly caused by bacteria with or without clinical manifestations

what is a recurrent reinfection?

implies a different causative organism and is usually limited to the bladder

what is a recurrent relapse?

involves same causative organism; implies focus of infection in renal or prostatic parenchyma

what is the ruleout for recurrent relapse?

UTIs within 6 months or less from current episode are likely caused by the same organism

what are the affected populations for UTI?

• more frequent in women than men

• older adults

• pregnant women

• renal transplant patients

• patients with spinal cord injuries

• patients with catheters

• genitourinary tract abnormalities

what is asymptomatic bacteriuria (ABS)?

presence of bacteria in urine in significant quantities, but without genitourinary (GU) signs or symptoms of infection

when does ABS require treatment?

pregnant women, patients about to undergo instrumentation of the GU tract

when does disease occur in ABS?

multiplication of organisms in urinary tract interferes with normal function of involved organ

the urinary system is ______ to colonization and subsequent bacterial infection

normally resistant

what are urine characteristics?

extremely high osmolarity, low pH, very dilute urine fails to grow most bacteria, men have prostatic fluid that is inhibitory, urine flow has a washing effect

in normal conditions the urinary tract efficiently and rapidly _____ virulent and avirulent microganisms

eliminates

______ can be transiently colonized by microorganisms

the urethra

what is frequently considered a good “medium” for bacterial growth?

urine

what can contribute to lowered resistance to urinary infection?

high ammonia concentration, hyperosmolarity, lowered pH, sluggish blood flow in the renal medulla

urine has been shown to inhibit the __________ functions of polymorphonuclear cells

migrating, adhering, activation, and killing

how can the immunosuppressive effect of urine be reversed?

due to the presence of acid-labile mucopolysaccharides that inhibit bacterial adherence along the lining of the bladder

what are the pathogenesis and course of UTI determined by?

the anatomy of the organs involved —> upper or lower UTIs

what are upper UTIs and assiciated diseases?

renal parenchyma —>pyleonephritis

ureters → ureteritis

what are lower UTIS and associated diseases?

bladder→ cystitis

urethra → urethritis

prostate → prostatitis

what are UTIs associated with in pediatrics?

long term medical problems

-hypertension, impaired renal function

what are UTIs associated with in adults to age 65?

low incidence in men unless GU abnormalities

-20% of women experience UTIs

what are UTIs associated with in geriatrics?

increased risk, especially with comorbidities, increased instrumentation

men: uropathogenic conditions caused by prostate

women: bladder prolapse and fecal incontinence

what are the microbial virulence factors of UTIs?

adherence, biofilms, calculi formation (kidney stones), capsular polysaccharide, hemolysis, lipopolysaccharides, toxin production

why does institutionalized care have increased UTIs?

urinary tract instrumentation, GU tract abnormalities, increase in frequency of ASB

why is there increased UTI in pregnancy?

physical and hormonal changes -→ increase bacterial adherence and impair urinary flow

why do people with renal transplantation have UTIs?

immunosuppression, foreign bodies, stricture, obstruction, scarring, other abnormalities, diabetes mellitus

→ can lead to specticemia

why do people with bladder catheterization have UTIs?

colonization of patient through catheters, duration of catheterization, appropriate catheter care, and host susceptibility

what are most STIs due to?

fastidious infectious agents

-routine urine cultures may not recover these organisms

how can STIs cause UTIs?

involve the genital tract, women have close proximity to the vagina and males have shared tract

what are the symptoms of neonates and children under 2 year old that have UTIs?

failure to thrive, vomiting, lethargy, fever

what are the symptoms of children older than 2 years that have UTIs?

dysuria, urine frequency, and abdominal or flank pain

what are the symptoms of adults with uncomplicated lower UTIs limited to the urethra or bladder?

dysuria with frequency, urgency, suprapubic pain, and hematuria

what are the symptoms of upper UTIs?

flank pain, nausea, vomiting, fevers, chills, night sweats, and costovertebral angle tenderness

-most older adult patients have atypical presentation

when can dysuria be seen in ?

UTIs caused by herpes simplex virus (HSV), chlamydia trachomatis, neisseria gonorrhoeae

what routes can bacteria may access to urinary tract?

ascending route, hematogenous route, lymphatic pathways

what is the ascending route?

main route for UTIs in women due to shorter urethra creating an environment for easy introduction via sexual intercourse

what UTIs can occur via hematogenous spread?

gram positive bacteria, mycobacteria, fungi

what route is associated with gram negative bacteria?

ascending route

gram negative bacteria via hematogenous spread —>

more difficult to assess

what is usual flora of newborn?

sterile no flora

what is the usual flora of 1-3 day old?

staphylococci, enterococci, diphtheroids, mycobacterium smegmatis

what is the usual flora in prepubertal?

micrococci, streptococci (alpha hemolytic and nonhemolytic), coliforms, diphtheroids

what is the usual flora of adults?

lactobacillus acidophilus, staphylococcus epidermidis, streptococci (alpha hemolytic and nonhemolytic) e. coli, diphtheroids, yeasts, anaerobic streptocci, listeria spp.

what is the usual flora of pregnancy?

increase in l. acidophilus, yeasts, S. epidermidis

what is the normal flora of postmenopausal?

similar to prepubertal flora

what are the gram negative bacilli that cause that UTI?

E. coli, pseudomonas, proteus, klebsiella, acinetobacter, and enterobacter spp.

-may be polymicrobial

what is causes the most uncomplicated UTIs of GNR?

E. coli

what gram positive cocci cause UTIs?

group B streptococci, enterococci, staphylococcus saprophyticus, staphylococcus epidermidis, staphylococcus aureus

what is the gram positive cocci important in pregnancy?

group B streptococci

what is the gram positive cocci that is primarily in older men?

enterococci

what is the gram positive cocci that is common in sexually active women under 40 years?

staphylococcus saprophyticus

what gram positive bacilli that cause UTI?

bacillus spp. are almost always contaminants, diphtheroids, listeria monocytogenes in infants

what fungi cause UTI?

candida

-rare in healthy adults, more common in hospitalized patients

what population does mycobacteria cause UTIs in?

in HIV-positive patients

what is chlamydia trachomatis and neisseria gonorrhoeae present with?

urethritis, cystitis, and prostatitis

what are causative agents that cause UTIs in neonates from lower socioeconomic groups?

mycoplasma and ureaplasma

what is an emerging pathogen UTI?

gardnerella vaginalis

what viruses can cause cystitis?

adenovirus and HSV

what viral agents are associated with cystitis?

herpes simplex, adenovirus

when is urinary tract sterile?

urinary tract above the urethra in normal healthy individuals

what can contaminate urine?

vaginal biota

what can determine pyuria?

urine leukocyte count of at least 10/mm3, symptomatic women with pyuria without bacteriuria

most patients with catheter associated bacteriuria also have ____

pyuria

what are the two groups women with ASB are divided into?

true asymptomatic infection associated with pyuria, transient self-limited bladder colonization and no pyuria

what could contaminate the collection of urine?

normal vaginal, perianal, and interior urethral biota

what are the requirements for urine collection and transport?

• must be immediately refrigerated or preserved

• process within 2 hours

what can happen to the urine if you process it after 2 hours?

pH extremes, urea concentration, and antimicrobial agents

what should the urine volume be?

10-20 mL

how can boric acid help refrigerate?

hold the integrity of urine up for 48 hours at room temp

what is not preserved in additives?

leukocyte counts

what should the primary reports of rapid nonculture methodologies consist of?

identify the degree of pyuria, presence of nitriles, blood, and/or leukocytes esterase, presence or absence of bacteria or fungi

when should preliminary results be reported of rapid nonculture method?

within 2 hours after the collection of urine specimen

why is it not recommended to report gram stain of urine?

low sensitivity and the inability to distinguish viable from nonviable organism and pathogens from contaminates

what can gram stains reveal in direct specimen collection?

reveal the presence or absence of bacteria/yeast but cannot distinguish between mono or polymicrobial infections

what should a microscopic analysis of urine be performed on?

urine concentration and sediment analysis or cytospin technology

what happens if the uncentrifuged urine is negative for bacterial cells?

the urine sediment preparation for leukocyte examination should be stained

-presence of clinical findings of acute pyelonephritis, may suggest urinary obstruction or perinephric abcess

what does pyuria often indicate?

urethritis, cystitis, or pyelonephritis

what is an hemocytometer?

a more precise method using unconcentrated urine

what urine is recommended for detection of fungi and mycobacteria?

first morning specimen and large sample volumes

what can sediment be stained with for detection of fungi and mycobacteria?

calcofluor white and auramine stains and examined via fluorescent microscopy

what is the calcofluor white stain?

bind to chitin present in the cell walls of fungi and makes visualization easier; also bind to cellulose, which chemically resembles chitin

what stains mycobacteria?

auramine

what is not used for fungi?

quantitative colony counts

what are the draw backs of automated urine screening methods?

• may be expensive

• frequently require batching of specimens causing time delays

• have not been adequately evaluated for their efficacy in detecting low-grade bacteruria and funguria

what is a bioluminescence UTI screen?

detects bacterial ATP using enzymatic bioluminescent reaction of ATP with luciferin and luciferase

what is bioluminescence photometry?

if a significant number of organisms are present in the urine specimen, they will grow in the medium to a concentration detectable by photometry

what is the Bac-T- Screen using colorimetric particle filtration?

automated combination testing for bacteria and WBCs by membrane filtration and detection using safranin O dye

what is flow cytometry colorimetric particle filtration

detects and quantifies bacteria, WBCs, RBCs with color-coded scatter diagrams

what are the benefits and drawback of molecular screening?

• provides faster microbial identification than traditional culture techniques

• incapable of discerning organism viability

• shows promise with identification of the most common infectious organism (e.coli)

• not useful for uncommon infectious organisms

what specimens are not appropriate for analysis?

24 hour urine, foley catheter tips

when might a specimen be rejected?

inadequate or inappropriate method of collection or transport

how should you do a routine culture for urine?

plate to one nonselective and one selective medium, use calibrated loop, incubate for 24 hours,

-fastidious organisms require specific plating media for detection

how should you culture ASB?

• conventional or automated methods

• colony count should accompany any positive culture results to indicate ASB

• E. coli is the most frequent identified etiologic agent

how should you culture pyelonphritis?

• microscopic examinations of urine for leukocytes and bacteria

• drop of specimen may be inoculated into trypticase soy broth (TSB) for optimal recovery

what do suprapubic aspirates have?

low numbers of bacteria and possibly anaerobes