Assist Prof Microbiology
Dr. Syed Yousaf Kazmi

1. Discuss epidemiology of urinary tract infections
2. Define lower urinary tract infections and its various causes
3. Explain the patho- physiological changes
4. Describe the symptoms, signs and various medical conditions associated
5. Discuss the investigations and principles of management


Half to 1/3 human suffer a UTI during life

In USA 1 % of outpatient visit is due to UTI
 10 million doctor visits/ year

Half of women will develop UTI in lifetime
 Most of those will be during pregnancy
 Almost 95% UTIs –bacteria multiply at the opening of the urethra and travel up to the bladder

Commonest UTIs are Cystitis


Between the ages of 16 and 35 years

10% of women getting an infection yearly

Urinary tract infections may affect
10% of people during childhood

Most common in uncircumcised males less than three months of age

UTI in men is rare before 5 th decade

E. coli is most common etiological agent

“Infection of urethra/ urinary bladder is called Lower UTI”

Complicated UTI-when infection associated with functional/ structural abnormality

Uncomplicated UTI- infection with normal GUS

Primary UTI

Recurrent UTI

 Flushing action of urine
 Acidic urine inhibits pathogens
 The prostate gland in men secretes Zinc-fights bacteria

Surface IgA

Antibacterial substances from uro-epithelium

Low vaginal pH-inhibits
UTI causing bacteria

UNCOMPLICATED UTIs

Female anatomy

Pregnancy

Sexual intercourse

Less fluid intake

Family history
COMPLICATED UTIs

Urinary flow obstruction e.g. BPH, strictures, urethral valves, Ca bladder, stones, uncircumcised,

Fistulas e.g. recto-vesical, recto-vaginal etc.

Urinary catheterization

Renal/ vesicle stones

Systemic diseases e.g. DM, Spinal cord injury


Escherichia coli (86 %)

Staphylococcus saprophyticus

Klebsiella species

Proteus species

Enterobacter species

Citrobacter species

Enterococcus species

Others (viruses, fungi, parasites)

 Bacteria are introduced in urethra
 Bacterial factors e.g. pili of E. coli, IgA protease etc. overcome defense mech
 Multiply in urethra

Move into Urinary bladder by attaching uro-epithelium
 In bladder, multiply more readily

Urine is good culture medium

Usually surface epithelium involved

Deeper layers in chronic cases

Acute inflammation-Neutrophils,
RBCs, Protein leaks into bladder-in urine

 Dysuria
 Urinary urgency and frequency(a frequent, urge to urinate, but only passing small amounts or no urine)
 Sensation of bladder fullness
 Lower abdominal discomfort
 Flank pain and costo-vertebral angle tenderness
(referred pain)
 Cloudy, dark or strong smelling urine
 Haematuria
 Fever, body aches, lethargy


Off feed

Nausea and vomiting

Loose motions

Frequent urination
(problem in babies with nappy)


Cervicitis (inflammation of the cervix)

Vaginitis

Interstitial cystitis (chronic pain in the bladder)

Prostatitis
 Renal tuberculosis

Genitourinary malignancy

Vesicular/ urethral calculi

Any peri-urethral process


Cloudy, turbid, clear

Malodorous, normal odor

Reddish, brown or normal colored
 pH-acidic, alkaline, neutral
 Protein-usually present

Leukocyte esterase usually positive

RBCs-present, or absent


Numerous pus cells/HPF

RBCs variable

Motile or non motile bacilli are visible on direct examination

Presence of casts indicates??

URINE CULTURE &
SENSITIVITY

Proper urine sampling

Clean catch, midstream urine

Must be cultured within
30 min

Problems in children, catheterized patient


Semi-quantitative (single org
>10 5 /ml or urine

Antimicrobial sensitivity

Results informed to physician

Patient put on therapy

48-72 hrs procedure

Empiric therapy in serious cases


Improve hydration & encourage plenty of fluids

Pain killers for pain and aches

Antimicrobials if indicated

Empiric antimicrobials according to available data of hospital

Later confirm with Urine C/S results

Uncomplicated cystitis usually 3 days course of Nitrofurantoin,
Trimethoprim/sulfamethoxazole,
Ciprofloxacin or Co-amoxiclav