Transcript MICRO. ospe

RESPIRATORY BLOCK
Practical
2014
Streptococcus pyogenes
= Group A Strep
(treated by penicillin or macrolides if pt has allergy
to penicillin )
Carried by 10-25% of
many
in throat
often no symptoms
it is Cause of
• strep throat
• impetigo
• Necrotizing fasciitis
Gram +ve cocci in chain
Catalase negative
We do also grouping test to differentiate any of all sterpt. Groups you are
dealing with.we use antibodies against the cell wall of strept.
(Group A strept. Will have a reaction with Anti-A antibody.)
Just look like the Blood group test.
Streptococcus pyogenes (induces pus). = Group A Strept
Left. Gram stain of Streptococcus pyogenes in a clinical specimen
(with some pus cells(neutrophils)which make sure that it
induces pus). Right. Colonies of Streptococcus pyogenes on
blood agar exhibiting beta (clear) hemolysis (when put the agar
against light you will see a complete hemolysis zone (beta hemolysis) )
Strept.A is a Bacitracian sensitive.
– Bacitracin test is used for presumptive
identification of group A
– To distinguish between S. pyogenes
(susceptible to B) & non group A such
as S. agalactiae (Resistant to B)
– Bacitracin disk will inhibit the growth
of gp A Strep. pyogenes giving zone of
inhibition around the disk
Bacitracin sensitivity
Group A
strept. Is a
bacitracian
sensitive.
Srept.B is a
Bacitracin
resistant
Associated
with neonatal
sepsis &
meningitis.
Case 1
A 5 year boy was brought to
king Khalid University
hospital, outpatient
department complaining of
fever and sore throat. He had
regular vaccination history. On
examination his temperature
was 38.5° c, the tonsil area and
pharynx were obviously
inflamed with some foci of
pus.<<here you exclude viral
infection & think more about
bacterial’s
AB-herpis virus infection, very
much resembles bacterial
infections because it induces
pus & inflamed tonsillitis.
1. What is the differential diagnosis?
viral
or bacterial infection,e.g. (strept.A)&
(Corynebacterium diphtheria if unvaccinated)
2. What investigation should be done?
Swab & culture it (gram stain is not recommended because the oral cavity
is colonized by numerous normal flora)
CBC
• Lab tests
• The full blood count
showed a total white
cell count of
15000ml.Throat swab
culture showed
colonies with clear
haemolysis on blood
agar. They were
catalase negative .The
gram stain of these
colonies showed gram
positive cocci in chains
1. What is the likely identity of the
organism?
Catalase negative cocci in chain
(Streptococci) (we say it’s A if it’s bacitraican sensetive)
2. What is the best antibiotic therapy for
this child?
penicillin
3. If not treated what complication may
this child have after 6 weeks period?
• Rheumatic fever(the heart antigenic structure resembles very
much the bacterial antigenic structure,so the antibodies attack the heart instead of the
bacteria.the child then will develop leg pain)
• Acute glomerulonephritis
Streptococcus pneumoniae
(Pneumococci)
Causes two fatal diseases :
Pneumonia & meningitis
Virulence factor:
Its capsule alone is the complete
story of meningitis.
Pneumonia occurred in
immunocompromised
patients.(especially the humeral
immunity is impaired).
& Patient with impaired spleen
function.
Alpha-hemolysis (partial clearance)
• 2 strept. species Can
display Alpha-hemolysis:.
• "Viridans group
strept.(causes
endocarditis)“
• Srept. pneumonia.
Optochin Susceptibility Test
Optochin resistant
S. viridans
Optochin susceptible
S. pneumoniae
This test is done to
differentiate between:
Viridans & pneumococcus
Optochin
Sensitive
Strept.
Pneumoni
a is an
optochin
sensitive
Viridans
strept. Is
an optochin
resistant
CASE 2
Fluid or pus infiltrates
which causes
consolidation
A 28 Year Old Female
presented to the accident and
emergency of KKUH with a
sudden onset of fever, right
sided chest pain and
productive cough of purulent
sputum. On examination her
temperature was 39 °C. There
were Rhonci and dullness on
the right side of the chest. Xray showed massive
consolidation on the right side
of the chest.
Whole Lobe
consolidation=lobar
pneumonia
Symptoms: fever
with chills
1. What is the most likely diagnosis?
Pneumonia or (lobar pneumonia to be accurate)
2. What investigation should be done?
• X-ray
• CBC(leukocytosis)above11x10^3
• ESR
• Sputum analysis(not recommended
because it’s colonized by bacteria)
• Blood culture (sepsis may occure)
• LAB
TESTS
• The blood counts showed a
total white cell count
45,000/ ml 90% of the cells
were neutrophils. The
sputum culture showed
alpha haemolytic colonies
on blood agar. The gram
stain showed gram positive
diplococcic.which were
catalase negative This
organism was confirmed to
be optician susceptible.
Culture of sputum
3. What should have been the empirical therapy for
this case and why?
penicillin if sensetive (MIC>2 so can’t be used).
cephalosporins (Ceftraixone)
If meningitis is the case we treat with vancomycin &
ceftraixone
Sputum Microscopy
Organism: Mycobacterium tuberculosis:
Stain: Ziehl-Neelsen stain
Mycobacterium tuberculosis
(highly infectious<communicable disease>)
Growth on L.J medium( selective for
mycobacteria
Slowly growing,
takes 2 weeks to
grow
CASE 3
Abdul Karim is a 45 year old Saudi man
who was admitted to King Khalid
University Hospital because of 2-3 month
(chronic) history of loss of appetite,
weight loss, and on and off fever with
attacks of cough. Two days before
admission .he coughed blood
(haemoptysis) Abdul karim is diabetic
for the last 5 years. His father died of
tuberculosis at the age of 45 yrs.
Cavities or open TB is very
infectious.(need 2 weeks
isolation & anti TB
medications)
• On examination Abdul
Karim looked weak with
a temperature 38.6 °C,
CVS and Respiratory
system examinnation
was unremarkable.
• The chest X- ray done
showed multiple
opacities and cavities
(mean that it’s a
reactivated disease)
• The ESR was increased
(85 m /hour)
• What further tests
should be done?
• Sputum AFB smear
• Sputum
smear
showed AFB
• What is the
probable
diagnosis?
openTB,open
pulmonary TB
• How can the
diagnosis be
confirmed?
Culture on L.J. medium
PCR
Gram positive, cocci, in clusters
(Staphylococci)
If catalase positive,so
it is Staph.areus
(induces pus &
abscesses)
Staphylococci Stained in Pus
Vaginal Smear of a Person with Candida Vaginitis
May cause pneumonia in immunocommpromised pt.
Note epithelial cells, rod-shaped
bacteria, and Candida albicans in its
hyphal form
Candida albicans Producing
Germ tube
Dimorphic Candida albicans switching from
a yeast form to a filamentous form
Gram stain of candida: ovoid budingYeast
Chlamydospore
causes: oral thrush
Growth on Sabouraud's Dextrose Media
Gram stain of Candida albicans
Showing budding yeast celols
Aspergillus niger
Culture of Aspergillus niger(black).
Aspirgillus pneumonia need a biopsy
to diagnose it
Conidial head of A. niger
Aspergillus niger
Aspergillosis
Methenamine silver (GMS) stained tissue section of lung showing
dichotomously(45 degree division) branched
These information has been added after
listening to Dr.Fawzia practical lecture.
Good luck
Done by: Khulud Alenzy