Urinary Tract Infection Clinical Based Learning

Dr.T.V.Rao MD

Dr.T.V.Rao MD 1

Clinical Presentation

• A 30 years female patient presented with frequencency and urgency in Urination with raise of body temperature since 3 days.

• She also presented with lower abdominal pain since 4 days

• What can be your Provisional Clinical Diagnosis ?

Dr.T.V.Rao MD 2

Signs and Symptoms of Urinary Tract Infection

• Elevated temperature—(vital signs)

Elderly require > time to present with fever, may not have any increase in temperature → may even be hypothermic

Elderly at ↑’d risk for masked or absent fever response due to antipyretics, corticosteroids, chemo Rx, alcoholism, hypothyroidism, malnutrition and renal insufficiency

Studies indicate fever is a marker for serious infection & most important clinical indicator for antibiotic treatment

Other studies, fevers can resolve without treatment; antibiotics did not improve outcomes in elderly

Not always due to UTI—consider differential diagnoses: pulmonary or skin infections

Lack of fever may delay diagnosis Dr.T.V.Rao MD 3

• The provisional diagnosis can be a Urinary tract

infection (UTI ) • Define Urinary Tract Infection ? What are the possible etiological

agents ?

Dr.T.V.Rao MD 4

Organs Involved in UTI

The following organs are infected

• Kidney

• Bladder

• Ureters

• Do not include Urethra, Infections of Urethra is called as Urethritis, dealt under different clinical syndromes

Dr.T.V.Rao MD 5

What is a Urinary Tract Infection

• An infection of one or more structures in the urinary system. Most UTIs are caused by gram-negative bacteria, most commonly Escherichia coli or species of Klebsiella, Proteus, Pseudomonas, or Enterobacter, although other strains, such as Staphylococcus and Serratia, are emerging

Dr.T.V.Rao MD 6

Notes on pathogens * Escherichia coli : the commonest urinary pathogen causing 60-90 % of urinary infections * Pseudomonas, Proteus, Klebsiella and S. aureus are associated with hospital acquired infections because their

resistance to antibiotics favor their selection in hospital patients (catheterization, gynaecological surgery)

* Proteus infections are associated with renal stones Proteus produce a potent urease which act on ammonia, rendering

the urine alkaline * S. saprohyticus infections are found in sexually active young women

Dr.T.V.Rao MD 7

Rare Microbes causing UTI

• Streptococcus agalactiae

• Streptococcus milleri

• Other Streptococci

• Anaerobic Streptococci

• Gardernella vaginalis

Dr.T.V.Rao MD 8

Notes on pathogens

* Candida urinary infection is usually found in diabetic patients and immunosuppression

* Infection of the anterior urinary tract (urethritis) is mainly caused by N. gonorrhea, staphylococci, streptococci and chlamydia

* M. tuberculosis is carried in blood to kidney from another site of infection

(e.g. respiratory T.B.)

Dr.T.V.Rao MD 9

What is the Basis of Diagnosis of Urinary Tract Infection ?

Dr.T.V.Rao MD 10

Diagnostic Criteria

Pyuria • A host response to infecting bacteria causing an increase

of white blood cells or pus in the urine

• Associated with presence of both symptomatic and asymptomatic UTI’s in elderly

• Level of pyuria is ↑ when infected with a gram negative organism

• Most research finds this is so common that it has questionable value in UTI detection and as an indicator for Rx in the absence of clinical symptoms

Dr.T.V.Rao MD 11

Collecting the Urine

• There are several different methods for collection of a urine sample. The most common is the midstream clean-catch technique. Hands should be washed before beginning. For females, the external genitalia (sex organs) are washed two or three times with a cleansing agent and rinsed with water. In males, the external head of the penis is similarly cleansed and rinsed. The patient is then instructed to begin to urinate, and the urine is collected midstream into a sterile container.

Dr.T.V.Rao MD 12

Collected in wide mouthed container

• The urine collected in a wide mouthed container from patients

• A mid stream specimen is the most ideal for processing

• Female patients passes urine with a labia separated and mid stream sample is collected

Dr.T.V.Rao MD 13

Early inoculation a Priority

• Urine collected in sterile specimen container must be processed within 2 hours, or refrigerated and processed within 24 hours

• Urine collected in sterile specimen container with borate preservative should be processed within 24 hours (no refrigeration required)

Dr.T.V.Rao MD 14

Collection of Urine Catheterized Patients

• Another method is the catheterized urine specimen in which a lubricated catheter (thin rubber tube) is inserted through the urethra (tube-like structure in which urine is expelled from the bladder) into the bladder. This avoids contamination from the urethra or external genitalia.

Dr.T.V.Rao MD 15

Suprapubic aspiration

• On rare occasions, the health care provider may collect a urine sample by inserting a needle directly into the bladder (suprapubic tap) and draining the urine; this method is used only when a sample is needed quickly and technically competent staff are available

Dr.T.V.Rao MD 16

Specimen collected in Infants and Children

• Non invasive methods are safe and ideal

• Follow the Broomhall et al method

By tapping just above the pubis with two fingers place on suprapubic region after 1 hour of feed, tapping on at the rate of 1 tap/second for period of 1 minute, if not successful tapping is repated once again.

The child spontaneously pass the Urine and to be collected in a sterile container

Dr.T.V.Rao MD 17

Transport of Urine for Culturing Urine

• All collected specimens of

urine to be transported to laboratory with out delay

• Delay of 1 – 2 hour deter the quality of diagnostic evaluations.

• If the delay is anticipated the specimens are at preserved at 40c

• In field conditions Boric acid can be added at a concentration of 1.8 %

Dr.T.V.Rao MD 18

Wet Film examination of Urine

• All wet films to be examined with high power ( x 40 ) objective.

• Prepare the drop of urine after mixing the urine without centrifugation

• Transfer 0.05 ml on the middle of the microscope slide and cover slip is applied.

• The prepared specimen show a small excess of fluid along the edges of the cover slip.

• A approximate finding of 1 leukocyte / 7 high power fields corresponds to presence of pyuria.

Dr.T.V.Rao MD 19

Selection of Loop for Semi quantitative Method

Dr.T.V.Rao MD 20

Culturing of urine for Isolation of

Bacterial pathogens

• Semi quantitative culture

Select the Media

For common isolates

MacConkey agar

helps in differentiation of Lactose fermenting organisms from non lactose fermenting pathogens Dr.T.V.Rao MD 21

Culture Media for Isolation

• Blood agar helps in isolation of

fastidious, extracting strains

May extended incubation for isolation of pathogens for more than 48 hours with added atmosphere of 5 – 10 % co2

Dr.T.V.Rao MD 22

What you understand by Significant bacteriuria ?

• Significant bacteriuria in an asymptomatic patient is 100,000 or more colonies per milliliter of urine from a midstream, clean-catch specimen;

Dr.T.V.Rao MD 23

Mac Conkey’s agar showing Proteus and E.Coli

Dr.T.V.Rao MD 24

How you interpret counts ?

• Up to 104/ml considered normal

i.e. Insignificant

• 105/ml and above considered to

be Significant

• Concept valid only for voided

specimen of urine

• Exceptions - slow growing

organisms, patient on antibiotic

therapy, diuretic therapy

Dr.T.V.Rao MD 25

Most important point in Interpretation

• Yet many theories on Significant bactenuria are controversial.

• The reporting of results should be mainly based on clinical history.

• Even a true infection may contain only 103

• In such circumstances tests to be reported as probably or possibly significant

• A good coordination between a Microbiologist and Physician is the best solution to patients with Urinary tract infections.

Dr.T.V.Rao MD 26

What are different Biochemical tests you

perform different isolates ?

• Catalase test • Oxidase test • Nitrite reduction test • Indole test • Methyl red test • V P test • Citrate test • Decarboxylation tests Lysine, ornithine,

Arginine tests

Dr.T.V.Rao MD 27

Antibiotic Sensitivity

• Always use a pure growth of the isolates.

• Perform testing for antibiotic sensitivity with inoculum which is comparable to defined McFarland standards.

Dr.T.V.Rao MD 28

How you perform Antibiotic Sensitivity Testing ?

• All the isolated bacteria identified as pathogenic to be tested for Antibiotic Sensitivity/Resistance pattern by disk diffusion methods

Dr.T.V.Rao MD 29

Issues on Urinary Tract infection

Dr.T.V.Rao MD 30

Causative Pathogens and other implication

UTI in Women

• Escherichia coli—gram (-) etiologic agent in ~

80% of all UTI’s

• Research indicates primary source of microbial invasion is retrograde colonization by intestinal pathogens

• Other factors influencing colonization: vaginal pH, urethral length, capacity of bacteria to adhere to urothelium

Osborne, 2004

=

Dr.T.V.Rao MD 31

Urinary Tract Infection Why it is Important

Urinary tract infection—most common source of

bacteremia, a dangerous systemic infection in long-

term care facilities

Bacteremia—40 times more likely to occur in

catheterized than non-catheterized residents

Bacteremia leads to significant morbidity and mortality

in the vulnerable elderly

Dr.T.V.Rao MD 32

Clinical Problems manifesting as

Urinary tract Infections

• An infection of the

Genitourinary tract where the Microbes do not grow on selected media as in Mycobacterium tuberculosis

Gonococcus Nutritionally exacting or

anaerobic bacteria

Dr.T.V.Rao MD 33

What is Polymicromial bacteriuria

• Contamination most frequent cause of multiple microorganisms

• 25-33% in LTCF’s may be polymicrobic due to fistulas, urinary retention, infected stones, or catheters

Dr.T.V.Rao MD 34

Non Specific Urethritis

• Several conditions mimic Urinary tract infection which are associated with organism other than routinely isolated in simple and few selective media, they can be

Can be urethral or Bladder infections with

Chlamydia

Ureplasma Trichomonas, Few viruses

Dr.T.V.Rao MD 35

Serious Infections associated with UTI

• Acute pyelitis

• Pyelonephritis

• May lead to Bacteremia's detected by Blood culture

• A prominent infection with Staphylococcus aureus can cause above manifestations.

• Be prompt to diagnose Urinary Tract Infections

Dr.T.V.Rao MD 36

• Created by Dr.T.V.Rao MD for Microbiology Students in

Developing World • Email

• doctortvrao@gmail.com

Dr.T.V.Rao MD 37