Download Urinary Tract Infections Sara Gordon

Urinary Tract Infections
Sara Gordon
[email protected]
Introduction:
UTI = presence of microorganisms in the urinary tract that cannot be accounted for by contamination
 Asymptomatic  bacteremia or urosepsis
 Various classifications of UTIs – uncomplicated/complicated, upper/lower, recurrent, asymptomatic – see
below
o Lower UTI: occurs in the bladder or urethra (cystitis)
o Upper UTI: occurs in the kidneys (pyelonephritis)
Pyuria = the presence of increased numbers of polymorphonuclear leukocytes in the urine; evidence of an
inflammatory response in the urinary tract
Epidemiology: varies with age and gender
 Newborns – 6 months: prevalence of abacteriuria is ~1% and more common in boys
 1-6 years: more common in females (3-7% incidence vs 1-2% in males)
 Incidence continues to be more common in females, with about 1 in 5 women experiencing UTI at some
point in their lives, until age 65
o Prevalence of bacteriuria in adult men is <0.1%
 After age 65, the overall incidence of UTI increases substantially, with the majority of infections being
asymptomatic.
o Most likely results from obstruction due to prostatic hypertrophy, poor bladder emptying, fecal
incontinence in demented patients, neuromuscular disease from stroke, increased use of catheters
Etiology:
 Route of Entry
o Ascending, hematogenous (descending), and lymphatic pathways
o Ascending – common in females due to the short length of the female urethra. Once bacteria reach
the bladder, the organisms quickly multiply and can ascend the ureters to the kidneys
 This is the main cause of UTIs
o Hematogenous spread – usually occurs as the result of dissemination of organisms from a distant
primary infection
o Lymphatic pathway – there are lymphatic communications between the bowel and kidney, as well
as the bladder and kidney, but no evidence that organisms are transferred to the kidney via this
route
 Host Defense Mechanisms
o Urine under normal circumstances is capable of inhibiting and killing microorganisms
 Low pH, extremes in osmolality, high urea concentration, and high organic acid
concentration
o Bacteria in the bladder stimulates emptying of the bladder; patients who are unable to void urine
completely are at greater risk of UTI
o Presence of Lactobacillus and circulating estrogen levels
 In premenopausal women, circulating estrogen supports growth of lactobacilli which
produces lactic acid to help maintain a low vaginal pH
 Bacterial Virulence Factors
o E. coli has bacterial fimbriae – rigid, hair-like appendages which adheres to specific glycolipid
components on epithelial cells
Clinical Presentation:
 S/s of lower UTI: burning on urination (dysuria), frequent urination, suprapubic pain, blood in urine
(hematuria), and back pain
 S/s of upper UTI: may also present with loin pain, costovertebral angle tenderness, fever, chills, nausea, and
vomiting

Elderly patients frequently do not experience specific urinary symptoms, but will present with altered
mental status, change in eating habits, or GI symptoms
Diagnosis:
 Urine collection:
o Midstream clean-catch: after cleaning the urethral opening area, 20-30mL of urine is voided and
discarded, then the next part of urine flow is collected and processed
o Catheterization
 Note that catheterization may introduce bacteria into the bladder and procedure may be
associated with infection
o Suprapubic bladder aspiration: insertion of a needle directly into the bladder and aspirating the
urine
 Bacterial Count:
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
o
DiPiro Table 94-1
Pyuria: presence of pyuria in a symptomatic patient correlates with significant bacteriuria
o Defined as WBC >10WBC/mm^3
o Nonspecific and signifies only the presence of inflammation, not necessarily infection
Hematuria: frequently present in patients with UTI but is nonspecific
Proteinuria: found commonly in the presence of infection
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Classification:
1. Asymptomatic Bacteriuria (ASB)
a. Presence of bacteria in the absence of symptoms
2. Symptomatic abacteriuria
a. Pts experience symptoms such as frequency and dysuria, but do not have significant bacteriuria (<10^5
bacteria/mL)
3. Uncomplicated:
a. Occur in healthy women who do not have structural or functional abnormality that interferes with the
normal flow of urine or voiding mechanisms
i. Women typically have uncomplicated UTIs
4. Complicated
a. Those which are associated with conditions that increase the risk for acquiring infection, potential for
serious outcomes, or risk for therapy failure
b. Result from abnormality within the urinary tract that interferes with the normal flow of urine and
urinary tract defenses ie. Indwelling catheter, prostatic hypertrophy, obstruction, stone, neurologic
deficit
i. Men, children, pregnant women, and health care-associated UTIs are considered complicated
5. Recurrent: >/= 2 UTIs occurring within 6 months or >/= 3 UTIs within 1 year
a. Reinfection: caused by a different organism
b. Relapse: development of repeated infections with the same initial organism, usually indicate a
persistent infectious source
1. Asymptomatic Bacteriuria (ASB):
(FYI: Nicolle LE, Bradley S, Colgan R, Rice JC, Schaeffer A, Hooton TM. IDSA Guidelines for the Diagnosis and
Treatment of Asymptomatic Bacteriuria in Adults. Clin Infect Diseases. 2005;40:643-654.)
Presence of bacteria without clinical symptoms
Diagnosis –
 Women: ≥ 105 cfu/mL of the same bacterial strain in 2 consecutive non-contaminated urine specimens
 Men: ≥105 cfu/mL in a single, clean-catch, voided urine specimen with 1 bacterial species isolated
 Catheterized patients: ≥ 102 cfu/mL in a single catheterized urine specimen in 1 bacterial species
 Pyuria is common in patients with ASB, however also accompanies other inflammatory conditions.
Therefore, the presence of pyuria alone is not sufficient to diagnose bacteriuria, and the presence or
absence of pyuria does not differentiate symptomatic v. asymptomatic urinary infections. Additionally,
pyuria accompanying asymptomatic bacteriuria is not an indication for antimicrobial treatment
Pathogens – Generally speaking, tend to be less virulent pathogens
 E. coli, Klebsiella, coagulase-negative Staph, enterococcus
Management Premenopausal, Nonpregnant Women:
 Screening for and treatment of asymptomatic bacteriuria is not indicated
o Asymptomatic bacteriuria is not associated with long-term adverse events such as HTN, CKD,
genitourinary cancer, or increased mortality
o Treatment of asymptomatic bacteriuria neither decreases the frequency of symptomatic infections
or prevents further episodes of asymptomatic bacteriuria
Not recommended for the routine screening for and treatment of asymptomatic bacteriuria in diabetic women,
elderly persons residing in the community, elderly persons residing in long-term care facilities, spinal cord-injury
patients, or patients with indwelling urethral catheters
Pregnant Women:
 ASB can have clinical consequences such as preterm birth and perinatal death of the fetus, or
pyelonephritis in the mother
o Consequences are reduced with the treatment of ASB with antibiotics
 Screening for and treatment of ASB are indicated in all pregnant women in early pregnancy
 Duration of antibiotics is not well defined; duration of antimicrobial therapy should be at least 3-7 days
o Selection of antibiotic is primarily driven by safety for both mother and baby
 Amoxicillin-clavulanate x 7 days
 Cephalosporin x 7 days
 Beta-lactams have ~70-80% efficacy
 Trimethoprim-sulfamethoxazole x 7 days – avoid use in 3rd trimester d/t possible
development of kernicterus and hyperbilirubinemia
 Nirtofurantoin has been used in pregnancy but must be used with caution as birth
defects have been reported
 Tetracyclines should be avoided b/c of teratogenic effects
 FQs should not be given d/t potential of inhibition of cartilage and bone
development in newborn
 Periodic screening for recurrent bacteriuria should be conducted after antimicrobial therapy
Urologic Interventions:
 Patients with asymptomatic bacteriuria who undergo traumatic genitourinary procedures have a high rate
or postprocedure bacteremia and sepsis
 Screening for and treatment of asymptomatic bacteriuria before transurethral resection of the prostate, or
other urologic procedures in which mucosal bleeding is anticipated, is recommended
 Antimicrobial therapy should be initiated shortly before the procedure
 Discontinued immediately following the procedure unless an indwelling catheter remains in place
2. Symptomatic Abacteriuria
 Clinical syndrome in which females present with dysuria and pyuria, but urine culture reveals <105
bacteria/mL
 Most likely infection with small numbers of bacteria, including E. coli, Staph, or chlamydia. May also be
caused by Neisseria gonorrhoeae, Gerdnerella vaginalis, and ureaplama urealyticum
 Most patient with pyuria will have infection that requires treatment
o
o
If antimicrobial therapy is ineffective, a culture should be obtained
If patient is sexually active, therapy for Chlamyida should be considered – 1gm azithromycin x1 or
doxycycline 100mg BID x7 days
3. Uncomplicated Lower UTI (cystitis)
 Recommended first-line agents for treatment of uncomplicated cystitis include: TMP-SMX, nitrofurantoin,
and fosfomycin
 Trimethoprim-sulfamethoxazole
o Usual adult dose: 160/800mg (1 DS tab) every 12 hours x 3 days
o Individually trimethoprim and sulfamethoxazole are bacteriostatic, but in combination are
bactericidal against most urinary pathogens
o Ratio of trimethoprim to sulfamethoxazole is 1:5 which results in peak serum concentrations of
1:20 which is optimal for synergistic activity
 Nitrofurantoin
o Usual adult dose: 100mg every 12 hours x5 days
o Almost completely absorbed following oral administration but is eliminated rapidly into the urine
and bile. This results in high urine levels making nitrofurantoin great for treatment of UTIs
o Low incidence of resistance
 Fosfomycin
o Usual adult dose: 3 g single dose
o Phosphonic acid derivative which irreversibly blocks bacterial cell wall synthesis through
inhibition of early cytoplasmic stages of peptidoglycan synthesis
o Spectrum: gram-positive and gram-negative bugs, including E.coli, Pseudomonas, and
Enterococcus, as well as MRSA, VRE, and ESBL-producing bugs
o ~40% absorbed after oral administration; eliminated unchanged in urine
 Fluoroquinolones are effective but have a propensity for collateral damage and therefore should be
reserved for uses other than acute cystitis
o Prevent the development of fluoroquinolone resistance
 Beta-lactams such as amoxicillin-clavulanate, cefdinir, and cefpodoxime for 3-7 days are appropriate when
other agents cannot be used.
o Generally they have inferior efficacy and more ADRs therefore should be used with caution
o Beta-lactams such as amoxicillin or ampicillin should not be used for empirical treatment due to
relatively poor efficacy and high prevalence of resistances
 Most pathogens produce beta-lactamases
4. Uncomplicated acute pyelonephritis
 Patients presenting with high-grade fever (>38.3 C) and severe flank pain should be treated as acute
pyelonephritis
o Severe = hospitalized w/ IV abx
o Milder = outpatient w/ PO abx
 All patients should have urine culture with susceptibilities if pyelonephritis is suspected
 Oral ciprofloxacin 500mg BID x 7 days (with or without 400mg x1 IV Cipro)
 Oral ciprofloxacin 1000mg ER x7 days or oral levofloxacin 750mg x5 days
 Oral trimethoprim-sulfamethoxazole 160/800mg BID x14 days
 Oral beta-lactams are less effective and typically not used
o An initial IV dose of long-acting parenteral antimicrobial, such as 1gm ceftriaxone or consolidated
24-h dose of aminoglycoside can be used with these oral agents
 Patients requiring hospitalization should be initially treated with an IV antimicrobial regimen:
o Fluoroquinolone, aminoglycoside, with or without ampicillin
o Extended-spectrum cephalosporin or extended-spectrum penicillin with or without an AG
o Carbapenem
5. Complicated UTIs
a. UTIs in men
 Single-dose or short-course therapy is not recommended – initial therapy should be for 10-14 days
 Trimethoprim-sulfamethoxazole or quinolones should be considered
6. Prostatitis
 Acute or chronic inflammatory condition affective the prostate, with ~5% of cases caused by bacterial
infection
 Chronic bacterial prostatitis – symptoms for at least 3 months, is one of the most common causes of
recurrent UTI in men
 S/S: sudden onset of chills and fever; perineal and low back pain; urinary urgency and frequency;
nocturia, dysuria, and generalized malaise
o May also complain of myalgias and arthralgias
 Fluoroquinolones are often the preferred abx due to good penetration in prostate
 TMP-SMX is also commonly used
 Duration of abx: 2-4 weeks (acute), 4-6 weeks (chronic)
7. Recurrent Infections
a. Relapse
 Recurrent of bacteria caused by the same microorganism that was present before initial
therapy
 Typically occur within 1-2 weeks after the completion of therapy
 Associated with inadequately treated upper UTI, structural abnormalities, or chronic bacterial
prostatitis
 May be ok to use the previous therapy, however new culture & sensitivity should be obtained
b/c resistance may have developed in which case you would need to switch to another agent;
could also start patient on new abx
b. Reinfection
 Recurrence of bacteria with a different organism that was present before therapy
 Most reinfections occur several weeks – several months after therapy
 Generally caused by colonization with Enterobacteriaceae from the lower intestinal tract
 Ok to use the same abx that were used for initial infection
- Prophylaxis can reduce the reinfection rate, before prophylaxis is initiated patients should be treated
conventionally with an appropriate agent
o Trimethoprim-sulfamethoxazole (1/2 80/400mg (SS) tab daily), levofloxacin 500mg daily, or
nitrofurantoin 50-100mg daily
o Prophylactic therapy is generally continued for 6 months
o If symptomatic episode occurs, the patient should receive a full course of therapy and then resume
prophylactic therapy
Patient Cases:
A 20 y/o WF presents complaining of burning on urination, frequent urination of small amounts, and bladder pain.
A clean-catch midstream shows gram-negative rods, C&S results pending, and urinalysis reveals WBC 1015cells/LPF (elevated)
- What type of UTI does this patient have?
o Uncomplicated cystitis
- How would you treat this patient?
o TMP-SMX 1 DS tab PO BID x3 days
o Nitrofurantoin 100mg every 12 hours x5 days
o Fosfomycin 3gm x1
- You choose TMP-SMX. What are some counseling points you should tell this patient?
o May cause photosensitivity
o Be sure to drink plenty of water
What if this patient’s urine culture showed <105 bacteria/mL?
- What type of UTI does this patient have?
o Symptomatic abacteriuria
- How should this patient be treated?
o
o
o
Although she doesn’t have bacteria in the urine, she does have pyuria which is typically indicative of
infection requiring antibiotics, probably an STD
Doxycycline 100mg BID
Azithromycin 1gm x1
A 28 y/o pregnant female presents to clinic for routine pre-natal care. Urine culture reveals >105 cfu/mL bacteria,
however, she does not complain of any symptoms.
- What type of UTI does this patient have?
o Asymptomatic bacteriuria
- How would you treat this patient?
o Amoxicillin-clavulanate x 7 days
o Cephalosporin x 7 days