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Microbiology 2 > M2 Urinary Tract Infections > Flashcards

M2 Urinary Tract Infections Flashcards

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1
Q

What body areas do upper urinary tract infections affect? What are the conditions called?

A

U-UTI’s (upper) – Ureters & Kidneys
Affect the ureters (ureteritis) or the renal parenchyma (pyelonephritis)

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2
Q

What body areas do lower urinary tract infections affect? What are the conditions called?

A

L-UTI’s (lower) – Bladder & Urethra
Affect the urethra (urethritis), the bladder (cystitis), or the prostate in males (prostatitis)

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3
Q

Why are UTI’s more common in females?

A

More common in females due to
1. The female urethra is shorter & lies in close proximity to the perirectal region; as a result, bacteria is able toreach the bladdermore easily
2. Hormonal change caused by pregnancy or post-menopause

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4
Q

Where are UTI’s common?

A

UTIs are the most common hospital and health care associated infection.

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5
Q

How much do UTI’s affect babies?

A

During the 1st year of life, UTIs occur in less than 2% in males and females

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6
Q

When in life do UTI’s affect males more?

A

In males, prevalenceincreases at the age of 60 due to the enlargement of the prostate, which interferes with urination

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7
Q

What medical conditions are predisposing factors for UTIs?

A

Diabetes is a predisposing factor for UTIs
Tumors, calculi & catheterization are also predisposing factors

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8
Q

What resident flora colonizes the distal portion of the epithelium of the urethra?

A

Resident flora colonizes the distal portion of the epithelium of the urethra:
1. Lactobacilli
2. Corynebacteria
3. Enterococci
4. CoNS

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9
Q

What are the most likely pathogens to cause an UTI?

A

Most common causative bacteria for UTI (pathogens):
1. Enterobacterales
(E. coli, Klebsiella, Proteus, others),
2. other GNB (Pseudomonas),
3. Enterococcus,
4. Staphylococcus (saprophyticus in community acquired, others in nosocomial),
5. yeast in inpatients.

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10
Q

Is urine considered a sterile fluid?

A

Urine is typically sterile:
But non-invasive collection of urine rely on specimen that has been contaminated

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11
Q

How is contamination of urine dealt with in the lab?

A

Quantitative diagnosis of UTIs is used to differentiate contamination, colonization and infection.

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12
Q

What organisms are typically encountered in community acquired UTIs?

A

Community acquired
1. Most common:
- E. coli (by far)
- Klebsiella spp.
- Other Enterobacterales
- Staphylococcus saprophyticus
- Enterococci
2. In more complicated UTIs (recurring infections)
- Proteus
- Pseudomonas
- Klebsiella
- Enterobacter

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13
Q

What typical organisms are found to cause UTI’s in nosocomial situations?

A

Hospitalized patients are most likely to be infected by
E. coli, Klebsiella spp., Proteus spp., staphylococci, enterococci, Pseudomonas aeruginosa, and Candida spp.

Highly antibiotic resistant microorganisms such as ESBL organisms, VRE.

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14
Q

What are the 3 major routes of infection?

A
  1. Ascending (most common in females)
  2. Hematogenous
  3. Lymphatic pathways
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15
Q

What is thought to be the modes causing ascending routes of bacterial infection in UTIs?

A

Ascent in association with
1. instrumentation most common healthcare-associated UTI
2. Common in females partially due to short urethra and proximity to anus, sexual activity can increase chances of contamination of the urethra.

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16
Q

Explain the hematogenous route of infection and the organisms most likely to be involved?

A

Blood-borne route, usually occurs as a result of bacteremia
Staph. aureus or Salmonella spp. particularly invasive
<5% of UTIs and rarely with GNB

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17
Q

How is the lymphatic route of infection thought to occur?

A

UTI caused by lymphatic flow into kidneysfrom increased pressure on the bladder

Insufficient evidence for significance of this route, ascending remains the major mechanism for development of UTI

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18
Q

What defenses does a person have to prevent UTIs from typically occurring?

A
  1. Urine – inhibits bacterial growth (low pH, urea)
  2. Constant flushing of urine from bladder
  3. Valves preventing reflux (backflow) in junction of ureter and bladder
  4. Host immune response to uropathogens
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19
Q

What defenses are weakened that are thought to result in increased likelihood of an UTI?

A
  1. Blockage urinary tract (slowing/stopping urine flush)
  2. Valves not working
  3. Resistance to uropathogens
  4. Invading superficial epithelial cells in the bladder (persistent infection)
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20
Q

What part of the body is infected when someone has urethritis and what are the symptoms?

A

Infection of the urethra
Symptoms: Painful/difficult urination (Dysuria),frequent urination

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21
Q

What organisms are typically expected to cause urethritis?

A

Commonly caused by C. trachomatis,Neisseria gonorrhea, and T. vaginalis
Considered to be sexually transmitted

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22
Q

What is inflammation or infection within the ureters called?

A

Ureteritis

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23
Q

What is the potential concern if someone has ureteritis?

A

Considered in combination with kidney infections- if infection is found in the ureters it indicates that the organism is moving towards the kidneys.

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24
Q

What is asymptomatic bacteriuria?

A

Specified count of bacteria in a urine sample collectedwithout symptoms.

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25
Q

Who is recommended to be screened for asymptomatic bacteriuria?

A

Screening recommended for pregnant females, males undergoing prostate resection and urologic procedures since it can lead to UTI or harm to fetus.

26
Q

What is cystitis and its symptoms?

A

Localized bladder infection that causes dysuria (painful/difficult urination) increased frequency and urgency of urination, bladder pain, and bloody or cloudy urine. Can also infect urethra.

27
Q

Who is acute urethral syndrome typically found in and what are the symptoms?

A

Acute Urethral Syndrome
Typically found in young, sexually active females
Classic UTI symptoms (dysuria, frequency, urgency)

28
Q

How many colony forming units is considered to be indicative of acute urethral syndrome and what is the key clinical feature?

A

Fewer colony forming units of bacteria found in the urine
Cutoff is 10^5 CFU/L instead of 10^8 CFU/L
Key feature: presence of pyuria

29
Q

What type of UTI is can cause back pain and what other symptoms?

A

Pyelonephritis - Bacterial infection that causes kidney inflammation and production of colloidcasts
–> Acute (abscesses) or chronic (scarring, fibrosis)
Symptoms: fever, lower back pain, dysuria, vomiting,diarrhea, chills

30
Q

What is Urosepsis and what are the symptoms?

A

Severe systemic blood infection caused by UTI
Presents as UTI plus additional symptoms like elevated temperature, heart rate, respiratory rate, or WBC count

31
Q

How can urosepsis be prevented?

A

Prevented by early treatment ofUTI

32
Q

What are the different type of urine specimens?

A
  1. Clean-Catch Midstream Urine
  2. Straight Catheterized Urine
  3. Indwelling catheter
  4. Suprapubic Bladder Aspiration
33
Q

Are sterile bags recommended to be to collect urine samples?

A

Sterile bags could be used for infants and children. Not highly recommended. Rejected in most labs.

34
Q

What type of urine collect is ideal for most people and why?

A

Mid-stream urine collection.
Least invasive.

35
Q

What are important instructions for patients to follow for a mid-stream urine collection?

A

Guidelines for proper collection with procedure clearly described should be provided.
1. Patients are instructed to wash their hands and clean the periurethral area (wiping 2-3 times front to back) prior to collection to prevent contamination.
2. Urine is voided then collected midstream.

36
Q

What are the pros and cons for a straight catheterized collection of urine?

A

Pros:
- Allows for collection of uncontaminated urine sample for uncooperative patients
Cons:
- More invasive
- Risk of introducing urethral pathogen into the bladder via catheter

Note: Done by trained healthcare professionals

37
Q

What type of patients are indwelling catherter urine samples taken from?

A

Indwelling catheter:
- For patients in long-term or are housed in the hospital
- Aseptic sample collection required

38
Q

What steps are needed for healthcare professions to take an indwelling catheter urine sample?

A
  1. Catheter must be clamped above the port to allow for freshly voided urine
  2. Gloves are needed when manipulating the catheter
  3. Catheter port/tubing wall must be cleaned with 70% ethanol and urine aspirated with needle and syringe
39
Q

What is the main risk for patients were indwelling catheter urine samples are taken from?

A

Patients are at high risk for bacteriuria

40
Q

What is done for a suprapubic bladder aspiration?

A

Suprapubic Bladder Aspiration:
- Bladder must be full
- Urine is withdrawn directly into a syringe through a percutaneously inserted needle
Contamination free specimen

41
Q

What are the benefits of doing a suprapubric bladder aspiration?

A
  1. Contamination free specimen
  2. If good aseptic technique is used, the procedure can be performed with little risk in premature infants, neonates, small children, and pregnant women.
42
Q

How long is an unrefrigerated urine specimen acceptable for lab analysis?

A

Maximum time for specimen at room temp is 2 hours

43
Q

If the urine cannot be processed in an acceptable amount of time for an unrefrigerated sample what are the options?

A

Urine must be immediately refrigerated or preserved with Boric acid
4 °C - bacterial count remains constant for up to 24 hours

44
Q

What are examples of two types of kits to preserve urine samples that can’t be refrigerated in transport?

A
  1. BD Urine Culture Kit
    - Contains boric acid, sodium borate, sodium formate
    - Can preserve bacteria without refrigeration for up to 48 hours
    - Minimum of 3 mL needed, might inhibit some organisms
  2. Starplex Scientific Urine
    - Preservative Tube
    - Uses a 10 mL sterile conical vial with boric acid
    - Maintains organism viability for up to 72 hours
45
Q

What are the purposes of screening procedures?

A

Developed to quickly identify infection and provide same day response to doctors.

46
Q

What are some different type of screening procedures?

A
  1. Gram or Methylene Blue Stain – Easy procedure. Recommended for suspected pyelonephritis or invasive UTIs.
  2. Pyuria – Uses hematocytometer. identifies and counts polymorphonuclear neutrophils. Not specific to UTIs
  3. Indirect indices – Strip & tube testing (Nitrate Reductase Test, Leukocyte Esterase Test, Catalase test)
  4. Automated & Semiautomated Systems - Detailed analysis, imaging and flow cytometry, limitations exist, does not replace manual microscopic analysis.
47
Q

What is one issue with screening procedures?

A

Screening procedures are insensitive to low colony counts (105to 106 CFU/L).

48
Q

What is the planting procedure for urine samples?

A
  1. Urine collected in sterile broad mouth container, label all media with specimen ID and your initials and date.
  2. Container mixed before inoculation
  3. Calibrated loop inserted vertically to withdraw precise volume of urine
    1 μL (regular MSU & catheter) or 10 μL (for aseptically collected urines)
  4. Loop streaked vertically across plate; then drawn perpendicularly to spread – loop is not reinserted into container or re-flamed
    If a 2nd plate planted, no need to incinerate
  5. Plates are incubated for 24 h before interpretation
49
Q

What other streaking pattern is acceptable for urines?

A

4 streak pattern also acceptable, without incinarating loop in between streaks

50
Q

What type of samples are aseptically collected for urines?

A

Aseptically Collected Urines include:
1. suprapubic aspirate
2. nephrostomy tube collection
3. Ileal conduits

Collected into sterile container or preservative tube.

51
Q

What size of loop and why is used for aseptically collected urines?

A

10 μL loop used for better sensitivity(i.e., to detect smaller amounts of bacteria)

52
Q

What is the traditional media used for urine specimens?

A

The classic planting combo is BA + MAC, incubated at 36 °C for 24-48 hrs aerobically

53
Q

How does chromogenic agar work to help detect UTI pathogens?

A

Chromogenic agar: Uses enzymatic reactions to allow differentiation of pathogens and presumptive identification of pathogens

Incubation:
35 – 37 °C
18 – 24 h
Aerobic Conditions

Also see “Chromogenic Agar Principles” under Lab notes for UTIs.

54
Q

What is the composition of chromogenic agar?

A

Composition of Chromogenic Media:

  • Agar
  • Peptone and Yeast Extract

Chromogen Mix
- β-galactosidase
- β-glucosidase

Tryptophan (Indicator)
- tryptophan deaminase

55
Q

What do you report for your urine culture if there is no growth the next day after planting?

A

If no visible growth:
No growth at 24hrs incubation = FRTF (further report to follow) and re-incubate for another night

56
Q

What makes urine culture interpretation challenging?

A

Urine cultures interpretation is complex due to the difficulty of distinguishing between infection and contamination as the criteria for positive culture is lowered from 10^8 CFU/L to 10^5 CFU/L

Look and understand tables in notes.

57
Q

What are the classifications or UTIs?

A

UTIs classified as complicated (history of persistent infections due to physiological factors), or not complicated.

58
Q

What is the dip-slide method for UTI collection/analysis? Is it still used?

A

Dip-slide (Dip n’count, Uricult etc.):
- Semi-quantitative
- Dip in urine & incubate
- growth compared to a scattergram

  • Outdated method
59
Q

What types of agar were various media ‘paddle’s (or dips) used? and its characteristics?

A

Media paddle normally consists of MacConkey agar and CLED (Cysteine Lactose Electrolyte Deficient) agar: inhibits Proteus, differential for LF/NLF

60
Q

What do you report if there is still no growth after another re-incubation at 48 hours?

A

If there is still no growth at 48 hours: “No growth at 10^6 CFU/L” if a 0.001ml or 1µL inoculum was used for example or “No growth at 10^5 CFU/L” if a 10uL inoculum as used.

61
Q

What is the quantify of CFUs if one colony is observed when a 1 uL loop is used? (/L and /mL)

A

With 0.001ml (or 1µL) loop, one colony growing equals 1,000 CFU/mL or 10^6 CFU/L.

62
Q

What is the quantify of CFUs if one colony is observed when a 10 uL loop is used? (/L and /mL)

A

With 0.01ml or 10µL loop, one colony equals 100 CFU/mL or 10^5 CFU/L.

Microbiology 2 (22 decks)

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