• Definitions of UTI
• Epidemiology of UTI
• Micro-organisms (aetiological agents/pathogens) associated with UTI
• Pathogenesis of UTI (host risk factors; virulence factors of E.coli (UPEC)
• Treatment and prevention of UTI
• UTI case study: diagnostic microbiology
LECTURE OVERVEIW:
• Definitions of UTI
• Epidemiology of UTI
• Micro-organisms (aetiological agents/pathogens) associated with UTI
• Pathogenesis of UTI (host risk factors; virulence factors of E.coli (UPEC)
• Treatment and prevention of UTI
• UTI case study: diagnostic microbiology
URINARY TRACT INFECTION (UTI).
• General definition of an uncomplicated UTI
‘ Microbial colonization of the UT by pathogenic micro-organisms, and infection of the
structures of the UT together with signs and symptoms of inflammation’
• UTI’s may be ascending or descending
• Endogenous (from us); non-communicable
• UTI may be ‘uncomplicated’ or ‘complicated’
• Uncomplicated UTI may progress to complicated UTI
– A complicated UTI is any urinary tract infection other than a simple UTI as
defined above. Therefore, all urinary tract infections in immunocompromised
patients, males, and those associated with fevers, stones, sepsis, urinary
obstruction, catheters, or involving the kidneys are considered complicated
infections.
UTI’s may be ascending or descending.
Descending means that the infection is going down from the kidney to the bladder.
Ascending means that the infection is going from the urethra to the kidneys.
It can be endogenous, this means that they are commensals from us, or they can be external
from an external source.
It can be non-communicable, which means that they are non-transmissible to other people.
They can be uncomplicated or complicated.
Uncomplicated UTI can progress to become a complicated UTI.
URINARY TRACT INFECTION: DEFINITION.
Significant Bacteriuria
Presence of at least 105 bacteria / ml of urine
May be symptomatic / asymptomatic
(in pregnancy)
Cystitis (Lower UTI)
Infection of the bladder. Most common UTI
Generally ascending
Syndrome of frequency,
dysuria (painful urination) and urgency
Foul smelling / bloodstained urine
, Acute Pyelonephritis (Upper UTI)
Infection of one or both kidneys.
Ascending (severe urinary reflux): complication of a UTI
Descending (haematological spread from distant infection)
Back, chills, fever, frequency and dysuria
Recurrent UTI
May be relapse or reinfection
relapse: recurrent UTI caused by the SAME microorganism that caused the original
infection
reinfection: recurrent UTI caused by a DIFFERENT microorganism
You are looking for significant bacteria.
This is the prescence of at least 10^5 bacteria per ml of urine. Can be symptomatic or
asymptomatic. Is asymptomatic in pregnancy. Pregannt woman give a urine sample
at every appointment, and they use this to see if the pregnant woman has an
asymptomatic bacteriuria. This can be indicative that they have a urinary tract
infection that remains asymptomatic and undiagnosed. It can be serious.
Cystitis- lower urinary tract infection. This is infection of the bacteria. This is
ascending so starts of low and works its way up the urinary tract. Urine stinks
because of the bacteria that are causing the infection, bloodstained urine.
Acute pyelonephritis- upper UTI. Can affect one or both of the kidneys. This can be
ascending generally. Can be a consequence of severe urinary reflux as a complication
of a urinary tract infection. It can be descending where you get a haemotological
spread from a distant infection. It can be an infection which is transmitted from the
kidneys down. This is symptomatic with pain in the back.
Recurrent UTI-relapse or reinfection
Relapse: infection has not been treated properly.
Reinfection- different microorganism causing that infection.
EPIDEMIOLOGY OF UTI.
Common infections.
Nosocomial infection – 25% this is because of catheters. If you insert a foreign body into a
body this is a huge infection risk.
PREVALANCE OF UTI.
Age (years) Females (approx %) Males
(approx%)
0-1 2 cases per 1000 live births: more common in boys
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