deck_1660726 Flashcards
Outline the three main defences against UTI
• Regular flushing during voiding • Length of urethra • Antibacterial secretions into urine
What does regular flushing during voiding do to help avoid UTIs?
• Removes organisms in distal urethra
Outline four host factors which predispose to UTI
• Short urethra - More infections in female • Obstruction • Neurological - Incomplete emptying, residual urine • Ureteric reflex - Ascending infection from bladder, especially in children
Give four ways obstructions occur in the urethra
• Enlarged prostate • Pregnancy • Stones • Tumours
Outline five bacterial factors which predispose micro-organisms to urinary tract infection
• Fimbriae allow attachment to host epithelium • Faecal flora migrate across periurtheral area • K antigen permits production of polysaccharide capsule • Haemolysins damage host membranes and cause renal damageUrease breaks down urea creating a favourable environment for bacterial growth
What bacteria types commonly cause UTI’s?
• Gram -‘ve bacteria
What is the commonest type of UTI?
• An infection of the lower tract - Cystitis
What is the most common cause of UTIs?
• Migration of e.coli from faecal flora across peri-urethral area
What can cause upper UTI’s?
• Haematogeneous (blood borne) or ascending routes of infection • Upper UTI (pyelonephritis)
Give three types of lower UTI
• Bacterial cystitis • Abacterial cystitis • Prostatitis
Give main symptoms of bacterial cystitis
• Frequency and dysuria, often with pyuria and haematuria
Give main symptoms of abacterial cystitis
• Frequency and dysuria, often with pyuria and haematuria
How could you tell the difference between bacterial and abacterial cystitis?
• Bacterial cystitis will be coupled with a bacteraemia
Give main symptoms of prostatitis
Fever, dysuria, frequency with perineal and lower back pain
Give two types of upper UTI’s
Acute pyelonephritis Chronic interstitial nephritis
What are symptoms of acute pyelonephritis
• Symptoms of cystitis • Fever and loin pain
What are symptoms of chronic interstitial nephritis
Renal impairment following chronic inflammation - infection one of many causes
What is an asymptomatic UTI?
• Covert Bacteriuria • Detected only by culture
Give two examples of when an asymtpomatic UTI would be important?
Pregnancy Childhood
What is the main organism responsible for UTI’s?
• Coliforms - e.coli - GRAM NEGATIVE SO STAINS PINK
What bacteria cause young women and hospitalised patients to develop UTI’s?
Staph Saprophyticus
Why is there a difference between the bacteria types which cause UTI in hospital and the community?
• Hospital provides extra risk factors, such as catherterisation which can provide a biofilm surface
What are two types of UTI?
• Complicated • Uncomplicated
What is an uncomplicated UTI?
• Vast majority of UTI’sFound in healthy women
What is a complicated UTI?
• Anything which isn’t in a healthy woman (Pregnancy, treatment failure, suspected pyelonephritis, males, pediatric)
How is an uncomplicated UTI investigated?
• No need for urine cultureInfection indicated by Nitirite/Leukocyte esterase dipstick testing
What is leukocyte esterase?
• An enzyme produced by WBCs which can be detected in the urine in the event of infection
What does a positive nitrite test usually indicate?
• That the cause of the UTI is a gram negative organism (usually e.coli)Gram -‘ves
What investigations need to occur in a complicated UTI?
• A urine sample must be take, from which a culture will be drawn so bacteria can be identified
Give four methods of collecting a urine sample
• Mid stream specimen • Adhesive bag over genitalia • Catheter sample from special tube in catheter • Suprapubic aspiration
How are urine samples collected?
• Mid stream, as urethera’s normal flora should not be collected
How can samples be collected from small children?
• Adhesive bag places over genitals
What is the issue with using an adhesive bag to collect urine from children?
• False positive rate of 20%
Where are catheter samples collected from?
• Needle placed up catheter tube • Not from the bag
What is suprapubic aspiration of urine?
• Needle placed through suprapubic region of pelvis into bladder and urine aspirated up
How are collected samples stored between collection and culture?
• Transported at 4*C with a small amount of boric acid in collection tube • Prevents bacterial division
• Prevents bacterial division What investigations can be performed on cloudy urine?
• Turbidity test • Dipstick testing
What is turbidity?
• Whether the urine looks cloudy - If so, indicative of UTI
What are four dipstick tests which can be performed on urine?
• Leukocyte esterase - Indicates presence of WBCs • Nitrite - Indicates presence of nitrate reducing bacteria • Haematuria - Present in UTI and many other conditions • Proteinuria - Present in UTI and many other conditions
In what 6 situations is microscopy used on urine culture?
• Kidney disease • Suspected endocarditis • Children under 6 • Schistosomiasis • Suprapubic aspirate • When requested
What is urine culture and what needs to occur before infection can be confirmed?
• A number of colony forming units must occur - >100,00 per ml (10^5 cfu/ml) distinguished bacteriuria/contamination
What are the five main advantages of urine culture?
• To investigate complicated UTIs • Gives epidemiology of isolates • Sensitivity testing • Specificity testing • Control of specimen quality ○ Can differentiate between properly collected and contaminated samples (poorly collected samples may contain epithelial cells)
What 5 details are needed to correctly interpret a urine culture?
• Clinical details ○ Symptoms ○ Previous antibiotics • Quality of specimen • Delays in culture • Microscopy • Organsims location
What is sterile pyuria?
Pus in urine
What does sterile pyuria indicate?
• A UTI is present but unable to be cultured
Give three situations where sterile pyuria would be present?
• Patient already treated with antibiotics • OR infected with bacteria that are difficult isolate or cultureOR can be due to tuberculosis or appendicitis (appendix stuck on bladder
What are three other causes of UTI symptoms
• Vaginal infection/inflammation • Sexually transmitted pathogens • Mechanical/physical/chemical causes
What are general treatments for UTI?
• Increase fluid intake • Address underlying disorders
How is an uncomplicated UTI treated?
• 3 day course of antibiotics • 3 day course reduces the selection pressure for resistance
What is given for complicated UTI treatment?
5 day course antibiotics
Should amoxicillin be used to treat complicated UTI’s?
• No50% of isolates (bacteria) resistance
How should pyelonephritis/septicaemia be treated?
• 14 day course of antibiotics • Use more potent agent with systemic activity
When is antibiotic prophylaxis indicated?
• Three or more episodes of UTI in one yearNo treatable underlying condition
What is antibiotic prophylaxis
• Single, low, nightly dose of antibiotics to prevent bacteria build up in static urine • All breakthrough infections documented
What is pyelonephritis?
• Infection in kidney
What is the worst case scenario in a UTI?
• Bacteria manage to invade blood stream from urinary tract • Gram negative septicaemia will occur
What are you likely to see in a culture of contaminated urine?
• Simple Squamous Epithelial cells
What is sensitivity of a test?
The rate of true positives
What is specificity of a test?
Rate of true negatives
