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Clinical Micro > Lecture 6 UTI > Flashcards

Lecture 6 UTI Flashcards

1
Q

How many UTI are there in community and in hospital

A

150 million

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2
Q

Uti is the cause for what % of GP surgery attendance in uk

A

3%

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3
Q

UTI are described as infection but not infectious, what does this mean

A

They are not communicable -spread like HIV etc from person to person

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4
Q

Infection of the Urethra is a UTI. True or false

A

FALSE. It is an STI.

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5
Q

What is the general definition of uncomplicated UTI

A

Microbial colonisation of the UT by pathogenic microorganisms and infection of structures of the UT with signs and symptoms of inflammation.

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6
Q

What type of microorganisms does the URETHRA have as normal flora

A

Faecal.

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7
Q

What is an ascending uti

A

COMES FROM PERIANAL AREA AND MOVEUPWARDS THROUGH URETHRA INTO BLADDER (own bacterial flora - endogenous - pushed up urethra). This is the most common type

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8
Q

What is a descending UTI

A

Occur in hospitals and critically ill patients, infections of blood steam descend from blood into kidneys where they can infect and lead to bladder infection.

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9
Q

What does an uncomplicated and complicated UTI mean

A

Female has infection of bladder (cystitis) which can get pushed up into kidneys therefore ‘get complicated’ as can cause renal scarring.

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10
Q

Briefly describe the process of how ecoli can attach and ascend to kidneys

A

1- if ecoli gave virulence factors can attach to epithelium of vagina in INTROITUS, which then becomes colonised
2- organisms can enter urinary tract via ureter and may be introduced to bladder where cystitis can occur.
3- oncein the bladder nd in presence of vesicourethral reflux, organism may ascend up ureter to renal pelvis and get pyelonephritis

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11
Q

What is significant bacteriuria

A

Presence of at least 10^5 bacteria/ml of urine
(As URETHRA have flora need a significant level to indicate infection)

May be asymptomatic/symptomatic

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12
Q

Cystitis (lower UTI) is what

A

Infection of bladder, most common UTI, generally ascending ‘

Syndrome of frequency, dysuria (pain on urination) and urgency (need to pee when just gone)

Foul smelling (from bacteria) may be blood stained if bacteria causing UTI produce haemolysins

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13
Q

What is acute pyelonephritis

A

Infection of one or both kidneys (upper UTI)
Ascending (sever urinary reflux) and complication of UTI
Descending (haematological spread from distant infection)

Back, chills, fever (38.5 or more deg), frequency and dysuria

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14
Q

How can a recurrent UTI be categorised

A

Relapse: recurrent UTI by SAME genetic type of microorganism that caused original treatment (from incorrect/inadequate treatment with antibiotics)

Reinfection: recurrent UTI caused by a DIFFERENT genetic type or microorganism

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15
Q

What percentage of hospital infections are UTI

A

23.2%

Second most common HAI

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16
Q

Why are UTIs common in hospital

A

Patients often on Antibiotics, or very unwell nd have catheters

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17
Q

Describe the trend of UTI in males and females with age using some facts and figures

A

In neonates they are more common in boys. Figures for neonates boy and girls is 2 cases per 1000 live births

Throughout life until 60-80yrs females are greatly affected more than men . At 60-80 years women still approximately double men however the values increased for both genders.

At 80+ female UTI statistic are double the males at 20% to 10%.

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18
Q

Why do female children aged 1-5 have more UTI than 5-18 years

A

Female genital system still developing (males longer urethra develop) and if wearing nappies then faecal bacteria can get into urethra and bladder much easier

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19
Q

What is proposed about why neonate boys have more UTIs

A

Unknown but presumed colonisation of foreskin, still developing UT

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20
Q

What % Of women have a UTI each year

A

5%

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21
Q

What % of women will have a UTI in their lifetime

A

50%

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22
Q

Length of average urethra

A

16-20cm

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23
Q

What 3 microorganisms are associated with community UTI and what % do they account for

A

Escherichia coli 80%
Staphylococcus saphrophyticus 10% (colonise perianal area in males and females so get honeymoon cystitis - coagulase neg)

Proteus mirabilis 10% (gram neg)

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24
Q

What microorganisms are associated with hospital UTI and %

A 
Escherichia coli (50%)
Proteus sp, klebsiella sp enterobacter sp ( gram neg antibiotic resistant organisms) 40%

Staphylococcus aureus and MRSA, coagulase negative staphylococci, enterococcus faecalis
Candida albicans 10%

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25
Q

Name some less frequent causes of UTI and why they are a cause

A

VIRAL cytomegalovirus very rare
Fungi - c albicans in hospitalisation, antibiotic use, catheterisation
Parasites: schistosomiasis haematobium (middle east, africa, india - burrow through skin in foot and lay eggs in liver which can travel through system and get lodged in the bladder)
Mycobacterium tuberculosis - HIV/immunosuppressed

26
Q

Name some community associated risk factors for women

A

Sexually intercourse due to short urethra
Contraceptive diaphragm and spermicidal condoms - press on urethra and meant to be left in vagina for hours after sex therefore prevent uronation and cleansing of urinary system

27
Q

Name some risk factors for UTI which can affect both genders and both in the community and in hospital

A

Extremes of age (neonates/70-80yrs
Abnormalities of UT (catheterisation, enlarged prostate, tumour - prevent voiding and cleansing of system )
Immunocompromised (HIV,diabetic, pregnancy - shift in hormones and structure of UT)

28
Q

Why are spermicidal condoms a risk factor for women in the community

A

Non oxinol. 9 is spermicide agent which ecoli are quite resistant but normal flora isn’t so get overgrowth of ecoli in genital system

29
Q

UTIs are associated with specific _ of E.coli (_). Based on , and _ antigens

FILL IN THE GAPS

A 
Serotypes
UPEC
O
F
K
30
Q

What attachment virulence factors do UPEC e coli have

A

Fimbriae - 100-400per bacterium
P fimbriae (PAP)
Type 1 fimbriae

31
Q

What evasion virulence factors do UPEC e coli have

A

Polysaccharide capsule e.g. K1 (sialic acid)

32
Q

What exocellular factors of virulence factors do UPEC e coli have

A

Haemolysin - release iron from RBC (act on RBC membrane) as UT low in iron.
Siderophores (enterobactin, aerobactin) - iron collating agents.

33
Q

What does P fimbrae bind to

A

Galactose disaccharide molecules on the P blood group antigen on uroepithelial cells.

34
Q

What is P fimbrae composed of

A

Main fimbrial protein (PapA) and adhesin (PapG). PapG allele II variant cause most cases of pyelonephritis

35
Q

What toxins are secreted by UPEC (extra)

A

Cytotoxic necrotising factor - affect intracellular signalling by modifying the Rho GTP binding proteins, actin polymerisation and is cytotoxic

also secrete an auto transporter toxin (SAT) - member of SPATE (serine protease autotransporters of enterobacteriaceae - also cytotoxic

36
Q

Adhesion of UPEC causes what effects

A

Binding to uroepithelial cells in the bladder induced widening of the junctions between squamous epithelium exposing cells for organism binding.

Get acute inflammatory response stimualting synthesis of Th1 cytokines by the uroepthelium, IL1, IL6 and IL8 which recruits granulpocuytes and macrophages. Increase in temp. Likely cytokine release due to LPS binding to TLR4 on uroepithelim

37
Q

What does type I fimbriae bind to

A

FimH binds to mannose receptor which is widespread in epithelial system of the bladder

38
Q

Any symptomatic UTI required what treatment

A

Antibiotics

39
Q

What 2 cases still need treatment even if asymptomatic with antibiotics

A

Preschool children with vesicoureteric reflux (VUR) - can potentially get renal scarring - may need trimethoprim for 5 years
Pregnant women - can cause low birth rate in neonates

40
Q

What are appropriate clinical samples for UTI before treatment with antibiotics

A

MSU
Bag-urine for new born babies. Place sterile bag and sellotape around urethra and wait until baby urinates but lots of contaminating bacteria from nappy for urethra.
Suprapubic aspiration better but more invasive - needle into bladder and aspirate out urine

Catether specimen (foley catheter) - catheter into urethra and held in bladder using a balloon. Best sample is put clamp on a part of the catheter and collect before the clamp so less bacterial growth

41
Q

What is the treatment if uncomplicated UTI

A

Nitrofurantoin (discovered in 1952 but not used often therefore not resistance) 50mg/qds

Trimethoprim if sensitive to nitrofurantoin 200mg/bd

42
Q

What is the moa of nitrofurantoin

A

Primary form is not active against bacteria but when taken up it is reduced by bacterial flavoproteins and then it becomes active to cause ribosomal protein and DNA damage, and pyruvate metabolism (multi target!!)
Can be given in pregnancy

43
Q

Why can trimethoprim not be used in pregnant women

A

Inhibit dihydrofolate reductase so DHF cant b reduced to THF, DNA production inhibited

Teratogenic risk - folate inhibitor risk to unborn child

44
Q

Treatment of complicated UTI (pyelonephritis)

A

Ciprofloxacin 500mg/bd , 10-14 days (consider initial IV administration followed by oral once afebrile (not feverish)

Ceftriaxone i.v. 1g once daily for 10-14 days (no oral)

45
Q

What is MOA of ciprofloxacin

A

Inhibit DNA gyrase as its a quinolone

46
Q

Why should ciprofloxacin be avoided in pregnancy

A

Can cause arthopathy joint disease

47
Q

What is the mOA of ceftriaxone

A

Inhibit PBP

48
Q

State some methods of preventing UTI

A

Low dose antibiotic nitrofurantoin 50-100mg at night
Cleanse genital area before sex
Single dose of antibiotic post sex and void urine
Drink lots of water - urinate.
Cranberry juice?!? Tablets as concentrated more effective

49
Q

Case study: 20 yr old female burning in bladder with frequency and dysuria. Urine foul smelling and she has recurrent UTIs.

What is the likely causative agent

A

Ecoli (community)

50
Q

Case study: 20 yr old female burning in bladder with frequency and dysuria. Urine foul smelling and she has recurrent UTIs.

Why is it important to confirm infection cause

A

Ensure appropriate antibiotics are given for correct aetiological agent. Also consider sensitivity patterns, may be resistant to nitrofurantoin or trimethoprim

Avoid further complications.

51
Q

Case study: 20 yr old female burning in bladder with frequency and dysuria. Urine foul smelling and she has recurrent UTIs.

What is the ideal sample collection and transport method

A

MSU in container with 1.8% v/w boric acid (red top), 20ml.

Transport ideally <24hr but boric acid acts as ‘preservation’ so could ‘preserve’ bacteria for 72
Boric acid also prevents overgrowth of bacteria in sample during transport
Refrigerate at 4 deg

52
Q

Due to the high frequency of urine samples what machines are used in clinical micro labs to process samples

A

iris iQ200 ELITE

UF 1000

53
Q

What other laboratory investigations non culture could be undertaken for diagnosis of uti

A

Microscopy (light and phase contrast) - examine for WBC, parasites, bacteria, RBC

54
Q

What does high wbc and high bacteria from microscopy indicate

A

UTI - shouldn’t be in mid stream urine

55
Q

What does large numbers of RBC indicate in mid stream urine

A

Renal trauma or carcinoma

56
Q

What is semi quantitative culture and how is it used in bacteria detection

A

Semi quantitative because it looks for bacterial numbers - significant number of infection is 10^5 per ml of urine for infection,

2 microlitres of MSU cultures onto CLED agar. To work out if meet infectious criteria of 10^5, the 20-200 colonies on CLED equates to 10^4/10^5CFU per ML.

57
Q

What colour are ecoli colonies and cled (cysteine-lactose-electrolyte deficient) and why

A

Ecoli ferments lactose which turns the bromomethyl blue to yellow due to acid production

58
Q

The majority of the time, basic ID such as present for coliforms is sufficient with colony description for E coli identification. True or false.

A

True

59
Q

Many labs now use what for identification (full) instead of API

A

MALDI TOF as result in 20 mins

60
Q

When performing API tests on ecoli samples to get full identification, what tests are commonly positive and which are negative for ecoli

A

Positive - indole, LDC/ODC, fermentation of glucose, sorbitol, mannitol

Negative - urease, citrate, gelatin

61
Q

What is the term used to describe high WBC count on microscopy but no organisms recovered on CLED

A

Sterile Pyuria

62
Q

Why may sterile pyuria occur

A

Renal TB - MTB doesn’t grow on cled
Antibiotics before sample - false negative.
STI urethritis infection (urethra), chlamydia most common STI.
Vaginitis - can get high WBC contamination in urine but not grow

Clinical Micro (9 decks)

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