Transcript Clinical Case Studies

Clinical Case Studies
Urine and Stool Cultures
Project- Clinical diagnostics
Each group of two are a team.
 You will try to culture and identify
the causative agents in a simulated
urine culture and stool culture
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Group work- Isolation streaks
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Urine culture
plates
EMB
MAC
TSA
MSA
Blood
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Stool culture
plates
EMB
MAC
TSA
Blood
MSA
Urine cultures
Please handle the specimens
carefully
 Use aseptic technique to avoid
contamination
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Origin of UTI
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In many cases, bacteria first travel to
the urethra. When bacteria multiply, an
infection can occur. An infection limited
to the urethra is called urethritis. If
bacteria move to the bladder and
multiply, a bladder infection, called
cystitis, results. If the infection is not
treated promptly, bacteria may then
travel further up the ureters to multiply
and infect the kidneys. A kidney
infection is called pyelonephritis.
When should a urine culture be
ordered?
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urinary tract infection, such as pain and burning
when urinating and frequent urge to urinate.
Antibiotic therapy may be prescribed without
requiring a urine culture for symptomatic young
women, who have an uncomplicated lower urinary
tract infection. If there is suspicion of a
complicated infection, or symptoms do not
respond to initial therapy, then a culture of the
urine is recommended. Pregnant women without
any symptoms may be screened for bacteria in
their urine, which could affect the health and
development of the fetus.
Clean catch specimen
Cleanse with a disposable wipe.
 Urinate a few drops into the toilet
and catch the stream of urine in
the culture container( Midstream)
 Place the lid on the container.
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Urinary Tract Infection
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(greater than 10,000 colony
forming units (CFU)/ml) is
considered a positive urine culture.
A culture that is reported as no
growth in 24 or 48 hours or less
than 10,000 CFU/ml usually
indicates that there is no infection.
Causative agents of urinary
tract infections
E. coli
 Proteus vulgaris
 Other gram – enteric pathogens
 Klebsiella
 Chlamydia
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Once we have diagnosed a UTI we treat the
patient with antibiotics. Typical antibiotics used
for UTIs include trimethoprimsulfamethoxamole, nitrofurantoin, and certain
penicillins such as amoxicillin.
In some cases, when we are pretty sure from
the symptoms that you actually have a UTI, we
will start antibiotics right after we get the
urine culture;
Repeat the culture after
treatment
If the culture result shows that we
need a different antibiotic, we can
always change.
 We repeat the culture 3-5 days
after starting antibiotics to make
sure that we are actually killing all
the bacteria, and again soon after
the antibiotics are finished to make
sure we killed everything that
needed killing.
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Stool cultures
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Make sure that you use aseptic
technique for your cultures
Gastrointestinal infections
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Bacteria
Viruses
Parasites
Fungi
Invasive Gastroenteritis(click on organisms for
more detail)Shigella sp.Entamoeba
histolyticaSalmonella sp.Campylobacter
jejuniEnteroinvasive E. coli
(EIEC)Enterohemorrhagic E. coli (EHEC)Vibrio
vulnificusYersinia sp.Francisella
tularensis,Helicobacter pylori
Salmonella
Undercooked
chicken
 Poor food handling
 Infected eggs(
raw eggs)
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C. difficile
C. difficile infection is usually acquired in
hospital , and almost all patients who develop C.
difficile diarrhea are taking, or have recently
been given, antibiotic therapy.
 Diarrhoea is the most common symptom but
abdominal pain and fever may also occur. In the
majority of patients, the illness is mild and full
recovery is usual, although elderly patients may
become seriously ill with dehydration as a
consequence of the diarrhea.
 Occasionally patients may develop a severe form
of the disease called 'pseudomembranous
colitis' or 'antibiotic-associated colitis' which is
characterised by significant damage to the
large bowel
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Staphylococcus aureus
Staphylococcus aureus-gram
positive coccusIngestion;
 Food poisoning; mayonnaise
containing and/or dairy products
 Heat stable enterotoxins; 5 types
labelled A, B, C, D, E
 Vomiting, little or no diarrhea, no
fever
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Food Poisoning
Bacillus cereus-gram positive rod
 Ingestion;
 Food poisoningType 1: emetic form;
heat-stable enterotoxin. mechanism
unknown
Type 2: diarrheal form; heat-labile
enterotoxin; stimulates adenylate
cyclase (increases
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Symptoms
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Type 1: starchy food= vomiting;
little diarrhea; no fever
Type 2: meats and cream sauces=
diarrhea; little vomiting; no fever