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prevalence of UTIs

one of the most common reasons for visiting primary care physician

50% of women have one by 30

incidence decreases with age

about 25% of women will experience a second episode within 6 months of their first UTI = recurrent UTI



presence of bacteria in urine - does not mean infection


asymptomatic bacteriuria

presence of bacteria in urinary tract + absence of symptoms

usually clinically insignificant unless woman is pregnant or has undergone invasive procedure in urinary tract


normal mechanisms that maintain sterility of urine

adequate urine volume

free flow from kidneys through urinary meatus

complete bladder emptying

normal acidity of urine

peristaltic activity of ureters

increased intra-vesicular pressure preventing reflux

in males: antibacterial effect of zinc in prostatic fluid


how are UTIs classified

based on location:
- upper: pyelonephritis
- lower: cystitis + urethritis

based on condition of the urinary tract or patient:
- uncomplicated
- complicated

based on evolution:
- acute
- chronic (symptoms persist over time)
- recurring (relapse or reinfection)



UTI confined to bladder

dysuria (painful peeing)
urinary frequency
urinary urgency
supra-pubic pain
hematuria ( blood in urine)
nocturia (peeing at night)
bladder tenesmus
absence of vulvar/vaginal discharge or irritation

absence of symptoms or physical signs suggests inflammation at other sites in urinary tract


differential diagnosis (UTI)

acute lower UTI (cystitis)

acute urethritis ( chlamydia or gonorrhoeae)

vulvitis - contact dermititis, allergic rxn, yeast infection, HSV infection

vaginitis/ bacterial vaginosis



clinical diagnosis that implies a more invasive infection

- fever
- flank pain
- nausea
- chills
- malaise
- headache

symptoms indicate: inflammation of the kidney and renal pelvis



inflammation/infection of prostate gland - acute or chronic

intrarenal /perinephric abscess: collection of pus in kidney or in the soft tissue surrounding the kidney


uncomplicated vs complicated UTIs

-occurs in patients with normal genitourinary tracts
-usually non- pregnant, premenopausal women of childbearing age

- structural or functional abnormality of the gentiourinary tract
- pregnant women, elderly, men, children
- chronic symptoms
- comorbid illness or immuno-compromised
- upper tract disease


complicated UTI infection definition

underlying abnormality that predisposes patient UTI or makes UTI more difficult to treat effectively


recurrent infections : relapse vs re-infection

- recurrence of infection by the same organism after treatment ends (possibly resistance)

reinfection: recurrence of infection by a different organism after discontinuation of treatment


pathogenesis of UTIs

UTI usually due to patients own intestinal flora: ascending route of infection (organisms enter the urinary tract in a retrograde fashion via the urethra)

complicating factors (catheters, nephrostomy tubes, surgery, urinary stones) results in:
- allows organisms to enter and persist in urinary tract
- alter the typical spectrum of organisms
- may have multiple etiologies


UTI Risk Factors

1. aging (increased incidence of diabetes mellitus/risk of urinary stasis, incontinence, impaired immune response)
2. female: short urethra, sex, contraceptives that alter normal flora, pregnancy
3. male: prostatic hypertrophy, anal sex
4. urinary tract obstruction: tumor or calculi, strictures
5. impaired bladder innervation
6. hematogenous spread


Etiology of UTIs

majority of UTIs are caused by single pathogen

enterobacterales are responsible for 90% of UTIs: gram neg bacilli, facultative anaerobes, common intestinal flora

E.coli is most commonly isolated (70%)


features of Uro-pathogenic E. coli

- uropathogenic E.coli have P fimbria which bind to P blood group antigen present on uro-epithelial cells (99% of population)

hemolysins, colinin V: resistance to complement in serum

K antigen: assoc. with upper tract infections

Type 1 fimbria: interbacterial binding and biofilm formation


common characteristics of uro-pathogens + examples

proteus, morganella, providencia (classical UTI pathogens)

produce urease - increases urinary pH = crystal/ struvite stone formation = obstructs flow - provides matrix

formation of biofilms: colonization of catheters

highly motile, produce fimbria for attachment


staphylococcus saprophyticus

typically associated with younger, sexually active females

1-5% of cystitis

Lab ID: resistance to novobiocin


UTI diagnosis via rapid in-office lab testing

dipstick testing

looks for nitrites and leukocytes produced by infection

leukocyte detection is sensitive but not specific

nitrite is sensitive for gram negative but highly specific

RBC detection is not sensitive or specific


quantitative culture for UTI diagnosis

urine culture: significant bacteriuria defined as 10^5/ ml

can use SBA, MacConkey agar, chromogenic agars

lower numbers may be significant in children or catheter collected specimens


urine specimen collection

clean catch mid stream specimens:
- most frequently used method
- urethra cleaned prior to collection
- first void urine allowed to pass to clear urethra
- mid-stream collected in sterile container

collection bags (children):
- used in young children
- often contaminated
- most meaningful result is a negative culture

indwelling catheters:
- urine obtained by inserting needle into catheter or through diaphragm
- preferable to obtain specimen from new catheter rather than old catheter

suprapubic aspiration/straight catheters:
- invasive
- specimen obtained directly from bladder


urine specimen transport

sent to and processed by lab ASAP

requires method of collection and time/date of collection on specimen

after 1-2hrs must be refrigerated

unless transported in boric acid tube urine not received in 24 hrs or not refrigerated will be rejected


antimicrobial therapy for UTIs

empiric therapy:
- based on most probable pathogens
- lower vs upper tract infection
- local rates of resistance
- acute infection vs relapse/re-infection

patient management is becoming more difficult due to increasing resistance to oral first line drugs


typical treatment regimes for UTIs

uncomplicated cystitis:
- nitrofurantoin
- fosfomycin
- TMP/SMX (24% res)
- ciprofloxacin
- beta lactam + aminoglycoside


common RTIs (bacteria)

pneumonia - community acquired, nosocomial


otitis media
pharyngitis - sore throat


RTI specimen


BAL/ bronchial washing
nasopharyngeal aspirates / swabs

endotracheal aspirates

sinus aspirates

typanocentesis - takes pain away right away = therapeutic + you get a specimen

throat swabs = diagnosis of group A strep


common bacterial RTI pathogens

strep pneumo
h. influenzae
moraxella catarrhalis
mycoplasma pneumoniae - no cell wall
chlamydia pneumoniae -- atypical cell wall
legionella pneumophila - strict intracellular susceptibility doesnt match vitro and in vivo

s. aureus
B. pertussis
gram neg/ anaerobes
s. pyogenes - primarily pharyngitis


what is pneumonia

an inflammatory condition of the lung primarily affecting the alveoli

typical signs/symptoms:
fever, cough (productive or dry), chest pain, shortness of breath

severity of disease and mortality vary considerably



S. pneumoniae - RTI

most common cause of of bacterial RTI

sm. gram positive diplococci
alpha hemolytic, bile soluble, optochin sensitive
growth often enhanced in CO2 atmosphere

most are encapsulated- most important virulence factor

colonizes the nasopharynx in 5-10% of adults and 20-40% of children

incidence increases in winter months


predisposition to pneumococcal infection

defective Ab formation
insufficient number of PMNs
day cares, military, prisons, shelters (close quarters)
chronic respiratory disease (COPD)
infancy and aging
diabetes, alcoholism, liver diseases