Download microscope

‫جامعت المنصورة‬
‫كليت الطب‬
‫قسم الميكروبيولوجيا والمناعت الطبيت‬
‫نموذج إجبثخ أسئلخ كتبة العملى لمبدح‬
‫الميكروثيولوجيب والمنبعخ الطجيخ لطلجخ‬
‫الفرقخ الثبلثخ ثكليخ الطت‬
‫العبم الجبمعى ‪2011 - 2010‬‬
‫‪1‬‬
3






2
MICROSCOPE
Complete the following sentences:

The magnification power of the ordinary light microscope = Objective Magnification x Eye
piece Magnification.

The oil used during microscopic examination is Cedar-wood oil.

The microscope used for examination of refractile organisms is Dark field microscope

The microscope used for examination of viruses is Electron microscope.

The microscope used for examination of detailed structures of bacteria as flagella is • Phase
contrast microscope.

The disadvantages of Electron microscope are
- Needs special experience.
- Expensive.
- Needs special sections (Ultra-thin section).

The uses of Fluorescence microscope are
- Demonstration of bacterial cell that appears shining in dark background.
- Immunofluorescent microscope.
Choose the best matched answer

Motile spirochetes are best visualized using:
a) Ordinary light microscope.
b)
Dark ground microscope.
c) Phase contrast microscope.
d) A+b.

Microbial organelles are best examined using:
a) Phase contrast microscope.
b) Dark field microscope.
c) Electron microscope.
d) Light microscope.

UVR is used in
a) Light microscope
b) Dark ground microscope
c) Phase contrast microscope
d) Immunoflurescent microscope
e) Electron microscope

Bacterial cells examined by fluorescent microscope are stained by:
3
a) Giemsa stain.
b)
Silver Fontana stain.
c) Acridine orange.
d)
Gram stain.
STAINING METHODS
Choose the correct answer:
1.
Gram stain is a:
a) Simple stain.
2.
c) Acid fast .
b) Gram -ve.
c) Alcohol fast.
b) Diluted carbol fuchsin. c) Concentrated carbol fuchsin
b) Iodine.
c) Carbol fuchsin.
All cocci are Gram positive except:
a) Staphylococci.
9.
b) Gram -ve.
Decolourization in Gram stain is done by:
a) Alcohol.
8.
c) Orange.
The counter stain in Gram stain is:
a) Crystal violet
7.
b) Violet.
Organisms which resist decolourization & retain the colour of the basic dye are called:
a) Gram +ve.
6.
c) Orange.
Organisms which are decolourized by alcohol & stained by the colour of the counter stain are
called:
a) Gram +ve.
5.
b) Violet.
By Gram stain, Gram negative organisms appear:
a) Pink.
4.
c) Special stain.
By Gram stain, Gram positive organisms appear:
a) Pink.
3.
b) Differential stain.
b) Neisseria.
c) Streptococci.
All bacilli are Gram negative except:
a) Enterbacteriaceae. b) Clostridium.
c) Vibrio cholera.
10. Staphylococci are:
a) Gram +ve.
b) Gram -ve.
c) None of the above.
4
11.
Ziehl- Neelsen stain is a:
a)
Simple stain.
b) Differential stain.
c) Special stain
12. One of the following organisms is acid &alcohol fast:
a) Staphylococci.
b) Neisseria.
c) T.B bacilli.
13. The counter stain in Z.N stain is:
a) Methylene blue.
b) Diluted carbol fuchsin. c) Concentrated carbol fuchsin
14. By Z.N stain, T.B bacilli appear as……..bacilli in blue background.
a) Pink.
b) Violet.
c) Orange.
15. The Hanging drop method is used to test bacterial:
a)
Motility.
b) Flagella.
c) Nutrition.
16. The different reaction to Gram stain is due to the following except:
a) Thicker peptidoglycan layer in Gram negative bacteria.
b) Protoplasm of Gram +ve bacteria is strong acidic.
c) Permeability in Gram +ve bacteria is less than in Gram –ve bacteria.
17. Simple stain gives an idea about
a) Shape of bacteria
b) Arrangement of bacteria
c) Motility
d) A+b
e) B+C
18. Value of iodine in gram stain is
a) Decolonization
b) Fixative (mordant)
c) Counter stain
d) Primary stain
e) Non of above
19. Value of methelene blue in ZN stain is
a) Decolonization
b) Melting of lipid wax in cell wall of mycobacterium
c) Counter stain
d) Primary stain
5
STERILIZATION & DISINFECTION
Define the following terms
a. Sterilization: The freeing of an article from all living organisms including bacteria and their
spores.
b. Disinfection: Removal of some types of pathogenic organisms usually not including spores.
c. Disinfectant: Are chemical materials used for sterilization of inanimate objects (but are
toxic to the human body) e.g.formaldehyde.
d. Antiseptics: Are chemical materials used for sterilization of animate surfaces, (not toxic to
the human body) e.g. alcohol.
e. Tyndallization: heating at 100C for 20 minutes for 3 successive days.
Answer the following

List some uses of UV radiation.
Sterilization of operating theatre.
Sterilization of inoculation chamber for viruses.
Sterilization of water.
Killing of vaccines.

List some uses of alcohol as a disinfectant.
- sterilization of skin and medical thermometers (having more power for
penetration).

List some uses of tincture iodine.
- used as skin disinfectant before operations.

List uses of ionizing radiation as a disinfectant.
- used for Sterilization of an article not stand the heat as rubber catheters, cat gut
or plastic syringes.

List uses of chloroform as a disinfectant.
- used as disinfectant of stool and used as water disinfectant.

Holding time of autoclave is
- 121C at 2 atmospheric pressure for 20 minutes.

Holding time of hot air oven is
6
160C for two hour.
180C for one hour.

Bacterial toxins can be prepared from fluid cultures by filtration.
Mention one method for sterilization or disinfection of the following:
a. Plastic syringe Ionizing irradiation
b. Bacteriological loop Red heat
c. Water UVR
d. Room disinfection UVR
e. Rubber stoppers Boiling at 100C
f. Powder containers: Hot air oven
g. Surgical instruments: Hot air oven
h. Glass pipettes Hot air oven
Give one example for:
a.
Moist heat sterilization below 100°C : Pasteurization of milk, Sterilization of serum ,
Sterilization of vaccines
b.
Culture media not sterilized in the autoclave: Litmus milk media
c.
Bacterial filters: Sietz filter
Choose the correct answer

The following Chemicals are disinfectants except:
a) Gluteraldehyde
b) Ethyline oxide
c) Hydrogen per oxide
d) Formaldehyde
e) None of the above
f) All of the above

Metal instruments can be sterilized by the following methods except:
a) Boiling.
b)
Autoclave.
c)
Koch's steamer.
d) Formaldehyde vapour.

Autoclave can be used for the following purposes except:
a) Sterilization of surgical dressings.
b) Sterilization of glass flasks.
7
c) Sterilization of Amies medium.
d) Sterilization of metal instruments.
e) b+d.

The best method for sterilization of sera and vaccines is;
a) Tyndallization.
b) Formalin.
c) Filtration.
d) U.V rays.

Pasteurization of milk is performed by:
a) Heating at 63˚C for 30 minutes then rapid cooling.
b) Heating at 56˚C for 1 hour then rapid cooling.
c) Heating at 63˚C for 1 hour then rapid cooling for 3 successive days.
d) Heating at 60˚C for 2 hours then rapid cooling for 2 successive days.

Which of the following disinfectants is used to destroy typhoid bacilli in stool?
a) Phenol 5%.
b) Formalin 2%.
c) Ditol.
d) Phenol 0.5%.
e) Alcohol 95%.
MEDIA
Multiple Choice Questions:
1) Culture media provide bacteria with:
a) O
b) CO2
c) Agar
d) H2O2
e) Nutrients
2) Media that inhibit the growth of certain bacteria while allowing other types of bacteria to grow
is:
a) Selective
b) Differential
c) Specific
d) Complex
e) Enrichment
8
3) Media that promote the growth of bacteria that might be present in a sample in low numbers is:
a) Selective
b) Differential
c) Specific
d) Complex
e) Enrichment
4) Which one of the following media is an enriched media for Neisseria species is:
a) Chocolate agar
b) Loffler’s serum
c) MacConkey medium
d) CLED medium
5) Which one of the following media is an enriched media for Diphtheria species is:
a) Chocolate agar
b) Loffler's serum
c) MacConkey's medium
d) CLED medium
6) Which one of the following media is a selective media for Diphtheria species is:
a) Chocolate agar
b) Loffler, serum
c) Blood tellurite agar
d) CLED medium
7) Which is the selective substance in Lowenstein Jensen medium is:
a) Malachite green
b) Potassium tellurite
c) Bile salt
d) Lactose
8) Which is the selective substance in MacConkey's medium is:
a) Malachite green
b) Potassium tellurite
c) Bile salt
d) None of the above
9) Which method is used for sterilization of sugar media:
a) Boiling
b) Koch sterilizer at 100◦c for 20 minutes on 3 successive days
c) Seitz filter
d) Autoclave
10) Which one of these is an example of transport media:
9
a) CLED medium
b) MacConkey's medium
c) Stuart medium
d) TCBS medium
11) Which one of these is an example of enrichment media:
a) Robertson cooked meat medium
b) MacConkey's medium
c) Blood agar
d) Selenite broth
12) What is the type of Lowenstein Jensen medium?:
a) Enrichment media.
b) Enriched media.
c) Selective media.
d) Indicator media.
13) What is the type of XLD medium?:
a) Enrichment media.
b) Indicator media.
c) Selective and indicator.
d) None of the above.
14) Which of the following media is sterilized in the autoclave?:
a) Dorset egg.
b) MacConkey's media.
c) Lowenstein Jensen.
d) Litmus milk
15) Which is true about blood agar?
a) It is ordinary medium
b) Used for detection of hemolytic reaction of bacteria
c) Sterilized by autoclave
d) It is selective medium for culture of E.coli
16) All the following statements are true about MacConkey’s medium except:
a) Contains lactose as test sugar
b) Contains neutral red as indicator
c) Contains bile salt to inhibit non intestinal bacteria
d) Contains phenol red as an indicator
17) On MacConkey’s medium E. coli forms:
a) Colourless colonies
b) Greenish pigmentation
10
c) Pink coloured colonies
d) Medusa head appearance
Match the following organisms with their respective culture media:
1. Neisseria gonorrhea
a. Blood agar
2. Tubercle bacilli
b. MacConkey’s medium
3. Diphtheria bacilli
c. Dorset egg medium
4. Salmonella
d. Loffler serum
e. Chocolate agar
True (T) or False (F):
1) Loffler serum is used for growth of diphtheria bacilli
True(
)
False(
)
2) Blood agar is used for culture of Neisseria gonorrhea
True(
)
False(
)
3) Dorset egg medium is Culture of Tubercle bacilli from contaminated samples e.g C.S.F.
True(
)
False(
)
4) Nutrient agar is sterilized in the autoclave.
True(
)
False(
)
5) Selenite broth is an example of enriched media.
True(
)
False(
)
6) Lactose fermenters give yellow colonies on MacConkey’s medium.
True(
)
False(
).
7) Malachite green is the selective substance in blood tellurite agar.
True(
)
False(
)
8) MacConkey’s medium is used for culture of urine samples.
True(
)
False(
)
9) Sugar media are sterilized in the autoclave.
True(
)
False(
)
10) Nutrient broth is sterilized in Koch's sterilizer.
True(
)
False(
)
11) Lactose fermenters give rose pink colonies on CLED.
True(
)
False(
)
11
COLLECTION OF SAMPLES FOR BACTERIOLOGICAL EXAMINATION
A. Respiratory tract infections:

Upper respiratory tract infections are mostly viral infections:
True(  )

False(
)
List some of the bacterial pathogens that can be recovered from throat culture in a case of upper
respiratory tract infection:
1. Staph. aureus
2. Strept. pyogens
3. C. diphtheria

What is the proper bacteriological sample to diagnose a meningococcal carrier?
Nasopharyngeal swab

While obtaining cultures from respiratory secretions, which of the following specimens is more
likely to be insensitive:
a) Sputum.
b) Bronchoalveolar lavage.
c) Transtracheal aspiration.
d) Lung biopsy.
B. Gastrointestinal infections:

A rectal swab is a better specimen than feces for diagnosis of intestinal infections.
True(

False(  )
)
For each of the following gastrointestinal infections, mention the most suitable sample for
diagnosis:
1. Cholycystitis: bile
2. Food poisoning: vomitus
3. Cholera chronic diarrhea: rectal tube

What is the role of glycerol saline transport media during transport of a fecal specimen?
prevent the overgrowth of commensal bacteria.
C. Urinary tract infections:

Mention two methods of preservation of urine samples if the transport to the lab will be delayed.
1. Specimen put in refrigerator at 4C for 24 - 48 hours.
2. Boric acid 1.8% .

For each of the following patients with suspected urinary tract infections, mention the most
suitable sampling method to obtain a urine specimen:
1. Patient with urine retention: Supra-pubic aspiration
2. Patient with an indwelling catheter: Catheterization of urethra
3. Adult ambulatory patient: Mid stream specimen
12

Cite indications for the use of each of the following techniques used to diagnose urinary tract
infections:
1. Midstream, clean catch specimen: Adult ambulatory patient
2. Aspiration from indwelling catheter:. Patient with a catheter
3. Suprapubic bladder aspiration: Patient with urine retention & pregnancy
D. Genital tract infections:

What is the most appropriate sample(s) for diagnosis of chronic gonorrhea in males?
morning drop, prostatic massage

What is the most appropriate sample(s) for diagnosis of acute cervicitis in females
Cervical swab
E. Septicemia:

List some of the indications of blood culture.
1. endocarditis caused by Strept. viridans
2. typhoid fever during the first week
3. brucellosis, and Meningococcal meningitis

What is the advantage of the big volume of broth in the blood culture bottle?
1. It provides good nutrition for multiplication of the organism,
which is usually present in small numbers.
2. It dilutes out any antibiotic or any antibacterial substances in the serum

The blood culture bottle should be discarded if the subcultures are repeatedly negative for:
1. 5 successive days.
2. 7 successive days.
3. 10 successive days.

Give recommendations for each of the following items to obtain maximal yield of
microorganisms in suspected cases of septicemia:
1. Minimize contamination: a strict aseptic technique using sterile syringe after
thorough sterilization of the puncture area
2. Timing of blood culture: Subcultures are made every day.
If results of subculture are negative for 7 successive days, discard the blood culture.
3. Volume of blood obtained : 5- 10 ml of blood
13
METHODS OF ISOLATION OF BACTERIA
IDENTIFICATION OF ISOLATED BACTERIA

What is the value of direct microscopic examination of specimens?
for demonstrating motility.

Mention one value of Gram stained smear of the clinical specimen.
determine the staining reaction of the organism; whether Gram positive or Gram negative,
their morphology (cocci, bacilli, etc.) size and arrangement.

What is the value of plating out technique for culture of specimens?
spreading out bacteria on the surface of solid media. Each bacterium will then divide repeatedly to
give rise to a separate colony.

List some of the methods for anaerobic culture of specimens
1. Use of deep media as deep agar tube and Smith – Noguchi media.
2. Use of media containing reducing compounds as Robertson’s cooked meet media
and thioglycolate.
3. Gas-bag jar.

Mention why is Robertson cooked meat media used for anaerobic cultivation?
The meat contains reducing substances e.g haematin and glutathione

The following are reducing substances integrated in anaerobic media except:
1. Sodium thioglycolate.
2. Sodium azide
3. Glutathione.
4. Haematin

Mention two pigment producing organisms and the colour of their pigments
1. Endopigment : Staph. aureus (golden yellow).
2. Exopigment : Ps. pyocyanea colonies (greenish)

List some colony characters by which an isolate can be identified on laboratory media
1. Pigment :


Endopigment : Staph. aureus (golden yellow).
Exopigment : Ps. pyocyanea colonies (greenish)
2. swarming : on solid media as in Proteus
3. Type of haemolysis on blood agar :



β haemolytic : Staph. aureus and Strept. Pyogenes
α haemolytic : Streptococcus viridans and Pneumococci
The following are some bacteria recovered from clinical samples, mention the most remarkable
colony character for each:
1. Proteus: swarming
2. Bordetella : glistening with appearance of bisected pearl and narrow zone of
haemolysis around
14
3. Mycoplasma: fried-egg shaped colonies .
4. Bacillus anthracis: On sheep blood agar, colonies are 2-5 mm in diameter, flat or
slightly convex with irregular wavy edges, have a ground-glass appearance, and
may have comma shaped projections from the colony edge.


Which of the following is the color indicator included in sugar fermentation media?
1- Phenol red.
2- Neutral red
3- Andrad's indicator.
4- Bromthymol blue.
The following are some of the biochemical reactions used for identification of bacteria, state the
principle of each
1. Indole test : the ability of certain bacteria to decompose the amino acid tryptophane
present in peptone to indole.
2. Methyl red: the ability of some bacteria to produce large amounts of acid from
fermentation of glucose, thus lowering the pH of the medium below 4.
3. Voges Proskauer's: Some bacteria ferment glucose with production of acetyl methyl
carbinol.
4. Urease test: Some organisms e.g. Proteus produce urease enzyme. Detection of
enzyme production can be used for their identification by alkalinity and increase pH
of the surrounding medium.
5. Oxidase test: Some bacteria e.g. Neisseria, Vibrio, Campylobacter, Pseudomonas,
produce oxidase enzyme, which can reduce oxidase reagent to a deep purple colour.

The following are examples of biochemical tests used for identification of bacteria, give an
example of bacteria that gives positive results with the test:
1. Indole: E.coli
3- Methyl red : E.coli
5- Oxidase : Pseudomonas auroginosa

2- Vogues Proskauer: klebsiella pneumoniae
4- Citrate : citrobacter
6- Urease: helicobacter pylori
List three uses of lab animals in microbiological diagnosis.
1. Identify certain pathogenic bacteria e.g. tubercle bacilli and Leptospira which produce
characteristic lesions, when injected in laboratory animals.
2. Distinguish between pathogenic and non- pathogenic species of bacteria.
3. Determine the virulence factor e.g. toxigenicity of a species. Injection of Diphtheria
bacilli in guinea pigs causes death of the animal within few days if the organism is
toxigenic.

Mention the name of the lab animal used to differentiate between Mycobacterium TB and
Mycobacterium bovis.
rabbits
15

List the methods of bacterial typing
1. Antibiotic sensitivity patterns.
2. Biotyping.
3. Serotyping.
4. Bacteriophage typing.
5. Bactericine typing.
6. DNA typing.
SEROLOGICAL TESTS
MCQ

Antibodies are found in the fraction of the blood that remains fluid after clotting. What is this
fluid fraction called?
a) Plasma
b) Serum
c) Lymph
d) Water
e) Urine

Which of the following serological tests depend on the action of enzyme on its specific
substrate:
a) Passive agglutination
b) Precipitation
c) ELISA
d) Immunodiffusion
e) Radioimmunoassay

The type of serological test depends on the nature of antigen. If we have a particulate antigen,
which one of the following tests could be used?
a) Immunofluorescence
b) ELIZA
c) Precipitation
d) Agglutination
e) Passive heamagglutination

The binding of antibodies to microbial epitopes or soluble molecules in a manner that inhibits
the ability of these microbes/molecules to bind to host cell surface is termed
a) Agglutination
b) Complement activation
16
c) Neutralization
d) Opsonization
e) Precipitin reaction

The term applied to the interaction of soluble antigen with soluble antibody that results in the
formation of insoluble antigen-antibody complex is
a) Agglutination
b) Complement activation
c) Opsonization
d) Precipitin reaction

Following a motor vehicle accident, a 25-year-old male require a blood transfusion. Blood type
tests done prior to the transfusion involve the use of IgM antibodies against A and B antigens on
erythrocytes. A positive reaction is an aggregate formation that is known as
a) Agglutination
b) Complement activation
c) Neutralization
d) Opsonization
e) Precipitin reaction

Immunofluorescence is an assay that relies upon antibodies or their ligands labeled with
a) Enzyme
b) Radioactive isotope
c) Enzyme plus its substrate
d) Fluorescent dye
True or false questions

The precipitin reaction is the term applied to the interaction of soluble antigen with soluble
antibody that results in the formation of Ag-Ab complexes large enough to precipitate from
solution.
True(  )

False(  )
)
Antibodies can bind to and cross-link cells or particles, causing an aggregate formation in the
agglutination reaction.
True(  )

False(
)
ABO typing of erythrocytes is done by a precipitation test.
True(

)
In the zone of Ag excess, there is sufficient antibody to form large lattices.
True(

False(
False(  )
)
Direct agglutination is the reaction that usually involves IgM antibodies that cross-link epitopes
on cells or particles.
True(  )
False(
17
)

A small quantity of blood of freshly drawn blood is mixed with pool of monoclonal anti-A or
anti-B human blood group antibodies. The blood shows agglutination with antibodies to blood
group A, but not with antibodies against blood group B. So, the blood group is type B.
True(

Double diffusion technique is based upon the diffusion of both antigen (loaded in one well) and
complement (loaded in another well) through an agar gel to form precipitin line at equivalence.
True(

False(  )
)
In radioimmunoassay , enzyme-labeled antibody is used for epitope detection.
True(

False(  )
)
False(  )
)
Increase in the level of antibodies in two serum samples from a patient infected with a microbe
is called rising titre.
True(  )
False(
)
Tackling
Mark the correct answer ( )

A tube agglutination test used in the diagnosis of enteric fever is called
Weil-Felix test

Pregnancy
Rh typing
Elek`s test used to detect the toxigenic Diphtheria bacilli is an example of
Agglutination test

Widal test
Direct Coomb`s test is used for the diagnosis of
Hemolytic disease of the
newborn

Coomb`s test
Complement fixation
test
Precipitation test
Wassermann test is a complement fixation test used for the diagnosis of
Gonorrhea
Enteric fever
Syphilis
18
STAPHYLOCOCCI

List some of the diseases caused by Staph.aureus
1. boils
2. osteomyelitis
3. meningitis


All the following are diseases of Staph.aureus except:
a-Acute rheumatic fever.
b- Food poisoning.
c-Toxic shock syndrome.
d- Exfoliative diseases.
All the following are ture about staphylococci except:
a-Gram negative.
b-Catalse positive
c-Produces beta haemolysis.

d- Arranged in clusters.
List the Gram staining characters by which you should suspect that an unknown organism
belongs to the family staphylococcacae.
1. Gram positive cocci
2. arranged in clusters
3. non spore forming
4. non motile.


Staph.aureus shows the following type of arrangement:
a-Clusters.
b- Chains.
c-Chinese letter.
d- Pairs.
Which of the following media is selective for the isolation of Staph.aureus?
a) Nutrient agar
b) Blood agar
c) Mannitol salt agar
d) DNAase agar

List the cultural characters of Staphylococcal isolates
1. Staphylococci are facultative anaerobes
2. optimum temperature: 37ºC.
3. It can grow in normal atmospheric CO2 concentration.
4. Staphylococci grow on ordinary media produce golden yellow endopigments.
5. On blood agar S. aureus cause  hemolysis.

Describe the colony characters of Staph.aureus on the following media
1. Blood agar :  hemolysis
2. Nutrient agar : golden yellow endopigments
3. Mannitol salt agar : yeloow colonies
19

Staph.aureus can be differentiated from other staphylococci by their appearance on blood agar.
True(  )

)
For isolation of Staph.aureus from biological samples, enriched rather than ordinary media are
required.
True(

False(
False(  )
)
List the differential tests used to identify Staph.aureus
1. Coagulase
2. DNAase
3. Mannitol fermentation

Following is a list of differential tests used to identify Staph.aureus, briefly state the principle of
each.
1. Coagulase test Principle: Coagulase causes plasma to clot by converting fibrinogen
to fibrin
2. DNAase Principle: Deoxyribonuclease enzyme hydrolyses deoxyribonucleic acid
(DNA)
3. Mannitol fermentation Principle:
Staph.aureus ferment Mannitol and produce :
1. Acid : detected by Andrade’s indicator  red colour
2. Gas : detected by inverted Durham's tube

List the chief test used to identify Staph.saprophyticus Novobiocin sensitivity test

What direct test confirms that an isolate belongs to the genus staphylococcus rather than the
genus streptococcus?
Catalase test

Which of the following methods of diagnosis is most sensitive to differentiate Staph.aureus
from other staphylococcal species?
1. Gram stained smear.
2. Colonial appearance.
3. Coagulase test.
4. Catalase test.


Which of the following species is sensitive to novobiocin?
a-Staph.aureus.
b- Staph.saprophyticus.
c-Staph.epidermidis.
d- Both (1+3).
Following are the properties of free coagulase except:
a-Heat labile.
c-Detected by slide method.
b- Freely secreted in the medium.
d- Detected by tube method.
20
STREPTOCOCCI
Choose the best answer

Group A beta haemolytic streptococci are
a) Strept.pyogenes
b) Strept. pneumoniae
c) Peptostreptococci
d) Strept. agalactiae

Puerperal sepsis is diagnosed by:
a) Urine culture
b) Blood culture
c) Wound swab
d) None of the above

The test used to detect streptococcal capsule is
a) cAMP test
b) Quellung reaction
c) Bacitracin test
d) None of the above

Following are the characteristics of Strept. pyogenes except
a) Fastidious
b) Beta hemolytic
c) Arranged in chains
d) Catalase positive

Dick toxin is
a) Streptokinase
b) Streptolysin O
c) Streptolysin S
d) Erythrogenic toxin

CRP stands for
a) Coagulase reacting protein
b) C-reactive protein
c) C-rheumatoid protein
d) Citrate reacting protein

Which of the following bacteria ferment inulin
a) Strept pyogenes
b) Neisseria meningitidis
21
c) Strept. pneumoniae
d) None of the above

Which of the following agents is used to test bile solubility?
a) Sodium hydroxide
b) Sodium taurocholate
c) Sodium dihydrogen phosphate
d) None of the above

Following are characterisitics of strept pneumoniae except
a) Ferments inulin
b) Optochin sensitive
c) Bile soluble
d) Beta hemolytic

Isolation of pneumococci can be attempted by intraperitoneal inoculation in
a) Pig
b) Rabbit
c) Guinea pig
d) mice

List the characters by which an organism is included in the genus streptococci
1. Gram-positive cocci
2. Arranged in chains or pairs
3. facultative anaerobe
4. catalase- negative .

List the characters by which bacterial growth on blood agar is identified as streptococcus.
1. On blood agar S. pyogenes cause  haemolysis.
2. Colonies are small (pin point) and translucent.

Name the three types of hemolytic reactions of streptococci and list an example for each
1. β haemolytic : Strept. Pyogenes
2. α haemolytic : Streptococcus viridans and Pneumococci
3. γ haemolytic : Group D strept.

List some of the diseases caused by beta hemolytic streptococci.
1. Pneumonia
2. Tonsillitis
3. Scarlet fever
4. Acute rheumatic fever
22
Genus Neisseria
Choose the best answer:

Which of the following is the proper sample in meningitis carrier?
a) CSF through lumbar puncture
b) Pharyngeal swab
c) Nasopharyngeal swab
d) Blood culture

Neisseria meningitidis can be recovered from all the following samples except:
a) Nasopharynx
b) Blood
c) Stool
d) CSF

The CSF in case of meningococcal meningitis has the following properties except:
a) Full of pus cells.
b) Full of lymphocytes.
c) Under tension.
d) Turbid.
State which of the following statements is true and which is false:

Culture is the most specific means of diagnosis of meningococcal meningitis
True(

Direct smear can be neglected during the diagnosis of gonorrhea
True(

False(  )
)
Neisseria can grown on blood agar in case chocolate agar is not available
True(

False(  )
)
All Neisseria are fastidious bacteria that require enriched media for isolation
True(

False(  )
)
Neisseria gonorrhea ferment glucose with the production of acid and gas
True(

False(  )
)
False(  )
)
Neisseriae are examples of intracellular pathogens
True(  )

False(
)
List the characteristics by which an organism is included in the genus Neisseria
1. Gram-negative cocci
2. aerobic or facultative anaerobe
3. usually occurs in pairs
23

Mention one method for rapid diagnosis of meningococcal meningitis other than the direct
smear
detection of meningococcal antigen in CSF by agglutination with specific
meningococcal antisera .

What is the value of the direct smear for diagnosis of gonococcal urethritis?
Detection of intracellular gram-negative diplococci is diagnostic especially in men .
BACILLUS GROUP

Bacillus group can grow on ordinary media
True( √

)
False(
)
)
False(
)
Bacillus group are spore formers
True(√

The disease caused by Bacillus anthracis is .....Anthrax............................................

Mc Fadyean stain is used to demonstrate the ... Capsule which appears as pink rim
around the blue bacillus............................................
Diphtheria

The medium used for isolation of C. Diphtheriae is:
a) Lowenstein Jensen Medium
b) Dorset's egg medium
c) Loffler's serum medium

The test used to diagnose susceptibility to Diphtheria is called
a) Schick test
b) Dick test
c) Elek test

The selective medium used for isolation of C. Diphtheriae is……Blood tellurite agar
…………

Describe the colonial characters of C. diphtheria on selective media:..… brown to
black because the tellurite are reduced intracellularly. Three types of colonies
are recognized, gravis, intermedius and mitis.

Compare between the arrangement of bacillus and Corynebacterium group in a Gram stained
smear:
- Bacillus:…………………arranged
in
chains……………………………
Corynebacterium:………… Chinese letters arrangements …………
THE GENUS CLOSTRIDIUM

List some of the diseases caused by Clostridium
24
1. ………… botulism ……………………………………..
2. ………… gas gangerene ……………………………………..
3. ………… Tetanus ……………………………………..



The following are causes of gas gangrene in man:
a- Clostridium histolyticum.
b- Clostridium septicum.
c- Clostridium perfringens.
d- All of the above.
Tetanus is caused by:
a- Bacillus coli.
b- Staphylococcus aureus.
b- Clostridium tetani.
d- Clostridium perfringens.
List the Gram staining characters of C.perfringens:
1. ………………… Gram-positive bacilli ……………
2. ………………… sporulated ……………
3. …………………capsulated ……………
4. …………………,non motile …………………


Pseudomembranous colitis is caused by:
a- Clostridium septicum.
b- Clostridium difficile.
b- Clostridium tetani.
d- Clostridium perfringens.
One of the major toxins of Clostridium perfringens:
a- Causes a white precipitate on Nagler medium.
c- Can cause hemolysis.

d- All of the above
C.tetani strains produce toxins with different antigenic properties.


b- Is a lecithinase
True(
False( √ )
)
List the cultural characters of the genus Clostridium
1. …………… Obligate anaerobe …………………………………
2. …………… at 37°C ……………………………………………
3. … C tetani produces colonies with complete haemolysis and swarming
4. In gas gangerene, the colonies are surrounded by a double-zone haemolysis, which
consists of an inner clear zone and an outer hazy zone

All the following are toxigenic diseases except:
a) Staphylococcal food poisoning
b) Tetanus
c) Rheumatic fever
d) Botulism
25

C.botulinum exotoxin binds neuromuscular junctions and interferes with acetylcholine release,
causing flaccid muscle paralysis.
True( √ )

False(
)
Toxins can be detected by:
1. ………… Cellular cytotoxicity test…OR …lethal effect in animal coupled with
neutralization of this effect by specific antisera ……
2. ………… latex agglutination test ………………………………………
3. …………… Enzyme-linked immunoassays …………………………
MYCOBACTERIA
Complete the statements:

Sample for diagnosis of pulmonary tuberculosis is
sputum ……………

The media used for isolation of M. tuberculosis from sputum is ……L.J.……

The media used for isolation of M. tuberculosis from CSF is……Dorset egg………

The animal used for diagnosis of human TB is…Guinea pig………………………

In tuberculin reaction, induration less than 5 mm is considered……Negative…..

The difference in staining between M. tuberculosis and M. leprae is the use of
……H2SO4…(25% in … tuberculosis & 5% in … leprae )…………………

The tuberculin protein (PPD) is derived from…old Mycobacterium tuberculosis broth culture
by chemical fractionation then precipitation by tri chloroacetic acid…

Mention the principle of tuberculin test……… cell-mediated hypersensitivity skin test. Based
on that individual previously infected with tubercle bacilli will develop hypersensitivity to
proteins
of
M.TB.
which
develops
6-8
weeks
after
infection
…………………………………….

Mention three causes of false negative tuberculin test:
…3 successive morning samples of
1. late stages of tuberculosis
2. Persons with impaired CMI response
3. acute viral infections
4. Improperly stored PPD

Describe the CSF picture of TB meningitis…………… less turbid than that in meningococcal
meningitis and contains excess of lymphocytes.

Describe the colony characters of M.tuberculosis on LJ medium
raised, rough, confluent, grayish, and dry ………………………………………

Describe the microscopic appearance of TB bacilli in a ZN stained smear and in fluorochrome
dye stained smear

ZN smear……… acid-fast bacilli appear pink in a contrasting blue background.

Fluorochrome smear …… bacilli appear as bright yellow fluorescent against dark background
……………
Select the best answer:
26

Each of the following statements concerning M. tuberculosis is correct EXCEPT:
a) After being stained with carbol fuchsin, M tuberculosis resists decolorization with acid
alcohol
b) M. tuberculosis has a large amount of mycolic acid in its cell wall
c) M. tuberculosis appears as a red rod in Gram-stained specimens
d) M. tuberculosis appears as a red rod in acid-fast stained specimens

Each of the following statements concerning M. tuberculosis is correct EXCEPT:
a) It is a facultative intracellular parasite, usually of macrophages
b) The high lipids content in the cell wall of M. tuberculosis lead to impermeability to
stains and dyes
c) The organism grows slowly, often requiring 3-6 weeks before colonies appear
d) The antigen in the skin test is a carbohydrate extracted from the organism.

Which of the following is (are) advantage(s) of tuberculin test :
a) Diagnosis of active infection in infants
b) Detects susceptibility to tuberculosis
c) All of the above
d) None of the above
FAMILY ENTEROBACTERIACEAE
Choose the best answer:

Which of the following statements is true about the Enterobacteriaceae family?
a) All members are motile.
b) All of them are normal intestinal flora.
c) They are facultative anaerobic.
d) They are oxidase positive.
e) None of the above.

Which of the following is true about E.coli?
a) Gram negative bacilli.
b) Grow on MacConkey’s agar and produce rose pink colonies.
c) Ejkmann’s test is used differentiate fecal from non-fecal strains.
d) Commonest cause of urinary tract infection.
e) All of the above.
27

Which of the following is true about Klebsiella species?
a) Contain capsule.
b) Motile.
c) Ferment glucose, maltose and mannite with production of acid only.
d) Indole test is positive while Voges-Proskauer test is negative.
e) a+c

Which of the following disease(s) can be caused by Salmonella typhi?
a) Enteric fever.
b) Food poisoning.
c) Septicaemia
d) All of the above

Which of the following is true about widal test?
a) It is a precipitation test.
b) The diagnostic titre in Egypt is 40IU/ml.
c) Detects salmonella O and H antigens.
d) Tube agglutination test.
e) c+d.

All of the following are selective media used for isolation of salmonella except:
a) Hekton enteric medium.
b) xylose-lysine-deoxycholate (XLD) agar.
c) SS agar.
d) Chocolate agar.
e) All of the above.

Concerning laboratory diagnosis of shigellosis:
a) All species are non-lactose fomenters.
b) Produce rose pink colonies on MacConkey's agar.
c ) All species are non-motile and non capsulated.
d) a+c.
28
e) None of the above.

Which of the following statements is true about proteus?
a) Gram negative rods.
b) Produce swarming on nutrient agar.
c) The tube motility test indicated a motile organism
d) Causes cystitis, pyelonephritis and prostatitis.
e) All of the above.
Plotting: Choose () the best-matched answer(s).
E.coli
Lactose
fermenters
Klebsiella
√
Citrocacter
√
Proteus
Salmonella
√
√
√
√
Non-lactose
fermenters
IMVC
Shigella
√
++ - √
IMVC
-+ - +
Motile
organism(s)
Capsulated
organism(s)
√
Some
strains
√
√
√
Red slant
and a yellow
butt on TSI
medium
yellow slant
and a yellow
butt on TSI
√
√
√
√
√
√
red slant and
a black butt
on TSI
29
√
True (T) or False (F)
1. Some strains of E.coli are capsulated
( T
)
2. Citrobacter is indole positive.
(
F
)
3. Klebsiella is citrate negative.
(
F
)
4. In widal test, when O Ag, H Ag for Salmonella typhi and Paratyphi A and
( T
B are all positive, this means recent vaccination.
)
5. Typhoid carrier is diagnosed by positive Vi antigen.
( F
)
6. Shigellosis is a strict human disease.
( T
)
7. Proteus species produce yellow colonies on CLED agar.
( F
)
8. Salmonella can grow on nutrient agar.
( T
)
9. Salmonella can be isolated from blood in second week.
( F
)
10. Fecal strains of E.coli can not grow on fluid MacConkey’s medium at 44°C
( F
producing acid and gas.
)
11. Salmonella paratyphi can ferment glucose, mannitol, maltose, and sorbitol
( T
with acid and gas production.
)
12. Kovac’s reagent is the reagent used in Indole test.
( T
)
13. Citrate test is based on the ability of an organism to use citrate as possible
( F
source of carbon and ammonium as source of nitrogen.
)
14. Proteus is urease test positive
( T
)
15. Salmonella typhi is H2S producing organism.
(T
)
THE GENUS VIBRIO; HAEMOPHILUS; BORDETELLA;
YERSINIA PESTIS; BRUCELLA; CHLAMYDIAE
Choose the single best answer:

All the following statements are correct about V.cholera except:
a) Comma shaped Gram-negative rods motile by single polar flagellum
(darting motility).
b) Ferments glucose, maltose, mannite and sucrose with production of acid only.
c) Gives a positive cholera-red reaction
d) Oxidase negative

Urea breath test is diagnostic to:
a) V cholera
b) Campylobacter
30
c) Helicobacter
d) Spirochetes

All the following statements are correct about Eltor vibrio except:
a) Was responsible for the last pandemic of Cholera
b) A more common cause of cholera outbreaks than classic cholera
c) Cause haemolysis to sheep RBCs
d) Sensitive to polymyxin B.

Which of the following statements are correct about H. influenza?
a) Doesn't need X factor
b) Grows alone on blood agar media
c) Causes common cold.
d) Blood culture can be used for isolation of H influenzae as many cases are accompanied
by bacteremia

Which of the following is incorrect about B. pertussis
a) Small Gram-negative cocobacilli with bipolar staining, non motile, encapsulated and non
sporulated.
b) Oxidase positive
c) Urease positive


Which of the following tests is used to detect non agglutinating blocking IgA antibodies for
diagnosis of brucellosis?
a)
Coomb antiglobulin test
b)
ELISA assay
c)
Brucellin
d)
Prozone phenomena
Chlamydia are stained by
a) Giemsa stain
b) Castanida and Machiavello stain
c) Fluorescent stain
d) Iodine stain
e) All of the above

Chlamydia are cultured on
a) Embryonated eggs
b) Fibroblast cell line
c) McCoy cells
d) A+B
e) A+C

All are true about Frei's test except
a) Intradermal test
31
b) Detects type IV hypersensitivity
c) Diagnoses lymphogranuloma venereum of Chlamydia
d) Diagnoses trachoma
e) None of the abbove

Motile yersinia
a) Y.pestis
b) Y.septicum
c) Y.pseudotuberculosis
d) All of the above
e) None of the above
True or false

In the diagnosis of V cholera diarrhea, mucus flecks from stools are inoculated on alkaline
peptone water pH 8.5.
( T
)

On TCBS medium V. cholera gives red colonies as they ferment sucrose.

When V. cholera is grown on peptone water, it produces indole & reduces nitrate to nitrite
which gives a red color on addition of indole.
(F
)

Eltor vibrio was responsible for pandemic of Cholera and is now a less common cause of
cholera outbreaks than classic cholera.
( F )

V. cholera is not examined by dark-field or phase-contrast microscopy for darting motility.
(F
)

Helicobacter can be cultured on nonselective media, as chocolate agar, or antibiotic-containing
selective media as Skirrow's medium.
(T
)

Type c H influenzae is the most virulent organism of Haemophilus species causing blood stream
invasion and meningitis in children younger than 2 years.
(F
)

S. aureus produces excess factor V when cultured on blood agar with H. influenza.
pneumonia can also produce factor V and shows positive satellitism.
( T )

Haemophilus species vary in their requirement for X& V factors.

Haemophilus influenza type b can be detected in the cerebrospinal fluid by Quelling reaction or
latex agglutination.
( T )

The widely used medium for isolation of yersinia is Bordet-Gengou agar containing blood.
( F )

IgG antibodies of brucella that appear during subacute stage of infection and persist for many
years interfere with detection of IgM antibodies and are called blocking antibodies or interfering
antibodies.
( F )

Inclusion bodies of Chlamydia trachomatis in scraped tissue cells are detected by staining with
Giemsa or iodine or by staining with fluorescent monoclonal antibodies.
( T )
32
( F
( T
)
S.
)
SPIROCHETES

What are the types of microscopes used for spirochetes diagnosis?
1. dark-field microscope
2. florescent microscope
3. phase contrast microscopy

What are the special microscopic characters of spirochetes family?
Helical coils, motile, unicellular and spiral-shaped organisms

Mention the pathogenic species and name of the diseases caused by spirochetes?
1. Leptospira species, which causes leptospirosis,
2. Borreli which causes Lyme disease, and relapsing fevers .
3. Treponema pallidum, which causes syphilis.

What are the stages of syphilis?
1. Primary stages: ulcer with a firm base (hard chancre)
2. Secondary stage: mucocutaneous rash, mucous patches, condylomata
3. Tertiary stage: cardiovascular and neurological involvement

List some of the tests for syphilis diagnosis?
1. Unstained fresh wet mount with dark ground microscope for motile treponemas.
2. Direct immuneofluorescsence using floulrecein-labelled antitreponemal antibodies
and examined by florescent microscope
3. Serological tests e.g. VDRL
4. PCR

The Wassermann test is a serological test; its principle is based on: classic complement-fixation
test using blood serum or cerebrospinal fluid.

The cardiolipin antigen is composed of: alchoholic extract of beef or ox heart muscle to which
cholesterol and lecithin are added

Why we should heat the serum at 56°C for 30 min. in Wasserman test? to destroy complement
normally present in serum

Hemolysis in Wasserman test means: negative serum, while no hemolysis means: positive
serum.

Mention the name of three treponemal tests:
1. Fluorescent T pallidum Antibody (FTA).
2. Treponema pallidum immobilization (TPI) test.
3. Treponema pallidum haemoagglutination (TPHA) test.

Mention the name of two non terponemal tests:
1. Venereal Disease Research Laboratory (VDRL)
2. Rapid Plasma Reagin (RPR) test
3. Wasserman test.
33

Can we use the Gram stain to diagnose the spirochetes? No, spirochetes cannot be stained by
Gram stain.

Mention two methods for diagnosis of spirochetes by using a direct smear:
1. Unstained fresh wet mount with dark ground microscope for motility
2. Florescent microscope. using floulrecein-labelled antibodies

Mention the cause that make the serological tests of little diagnostic value in relapsing fever:
due to the ability of borreliae to undergo multiple cyclic antigenic variations

Mention the cause behind the name of relapsing fever? Relapsing fever is named so, because the
most remarkable feature is its ability to relapse at regular intervals.
RICKETTSIA
Choose the single best answer:

Which of the following is correct about Weil-Felix test:
a) Proteus OX19, OX2 or OXK antigens are used as antigens for detection of rickettsial
antibodies.
b) Specific and sensitive.
c) Proteus strains have etiological role in rickettsial infections
d) Used in diagnosis of typhoid.

Which of the following is incorrect about rickettsia:
a) Cause typhus disease
b) By Machiavello stain organisms are bright red against the blue background of the tissue.
c) By Castaneda stain the organisms appear blue against a red background.
d) By Giemsa stain organisms appear red.
Fungal Diagnosis
Choose the single best answer:

Value of KOH (10-30 %) in direct examination of fungi sample
a) Inhibit saprophytic fungi
b) Inhibit bacteria flora
c) Keratolytic
d) All of above
e) Non of above

Complete undisrupted morphology of fungi is seen in
a) SDA
b) Wood light
c) EM
d) Slide culture or microculture
e) All of above
34

Stains used for fungal diagnosis are
a) Stained with lactophenol cotton blue
b) Histopathology by PAS & silver stain
c) Geimsa stain (histoplasma)
d) India ink (-ve stain) for Cryptococcus capsule
e) All of above

Media used for culture of fungi are
a) Blood agar
b) SDA
c) Dermatophyte test media
d) Potato carrot bile salt media
e) All of above

Capsulated yeast in clinical sample indicates
a) Candida
b) Aspergillus
c) Cryptococcus
d) Histoplasma
e) All of above

Combination of yeast and hyphae in sample indicates
a) Candida
b) Aspergillus
c) Cryptococcus
d) Histoplasma
e) All of above

identification of Candida albicans is done by all of the following EXCEPT:
a) Germ tube test and filament formation
b) Chlamydiospore on potaoo carrot bile salt media
c) Gram stain
d) Formation of macroconidia
e) All of above

In wood light, the wave length of UVR used is
a) 500 nm
b) 267 nm
c) 1000 nm
d) 360 nm
e) None of above

Value of chloramphenicol in SDA is (are):
35
a) Inhibit saprophytic fungi
b) Inhibit bacteria flora
c) Keratolytic
d) All of above
e) Non of above

Inhibition of saprophytic fungi is done by:
a) cycloheximide
b) KOH 10-30%
c) Chloramphenicol
d) All of above
e) None of above

Optimum temperature for the growth of fungi is
a) 37°C
b) 45°C
c) 25°C
d) 15°C

Recto verso examination of fungal culture means:
a) Examination of front color of the colony.
b) Examination of the texture of the colony.
c) Examination of back color of the colony.
d) Examination of front and back colors of the colony.
e) None of the above.

Filamentous fungi mostly appear in culture after:
a) 24 hours
b) Two days
c) One month
d) 2-3 weeks
True or False:

Serological diagnosis may play a role in diagnosis of mycosis
( T )

Most of pathogenic fungi are opportunists.
( T )

Mycotoxins are produced during fungal infections.
( F )
36
Laboratory Diagnosis of Human viral Infections
Choose the single best answer:

Viruses can be seen by:
a) Light microscope.
b) Ultraviolet microscope.
c) Phase-contrast microscope.
d) Electron microscope.
e) All of the above.

Viral antigens can be detected by:
a) ELISA
b) Complement fixation test.
c) Immunofluorescence.
d) All of the above.
e) None of the above.
Which of the following statements is true and which is false:

All viruses can be cultivated.
( F )

CPE of viruses may be specific
( T )

Viruses grown in cells can be detected by haemadsorption
( T )

Semicontinuous cell culture can be grown forever
( F )

Viral genomes can be detected by RT-PCR
( T )

Haemagglutination test is a virus-cell interaction
( T )

Haemadsorption test is used to detect viral antibodies
( F )

Quantitative PCR is the only method for quantification of viruses ( F )
Standard Infection Control measures for Hospital Acquired Infections
Q1Multiple choice Questions:

The most important for controlling nosocomial infections is:
a) Safe use of sharps
b) Hand hygiene
c) Sterilization of equipment
d) a+c
e) None of the above

The most fatal nosocomial infection:
a) Urinary tract infection
b) Post operative wound sepsis
c) Hospital acquired pneumoni
d) Nosocomial blood stream infection
37

How are antibiotic-resistant pathogens most frequently spread from one patient to another in
health care settings?
a) Airborne spread resulting from patients coughing or sneezing
b) Patients coming in contact with contaminated equipment
c) From one patient to another via the contaminated hands of clinical staff
d) Poor environmental maintenance

The length of time for proper washing of hands.
a)5 to 15 seconds
b)10 to 20 seconds
c)60 to 80 seconds
d)15 to 30 seconds
True or False:

I should use my bare hands to turn the water off and on.

When rinsing my hands, I should allow the water to run off my fingertips? ( F )

I can do my part to stop the spread of infection by proper hand washing.

Alcohol-based hand rub has been shown to be less irritating to skin than soap and water
( F )

The concentration of alcohol needed to be effective for hand hygiene is 40% ( F )
( F )
( T )
Put the hand washing procedure in order:
1. remove hand and arm jewellery
2. Wet hands with warm water
3. Apply soap
4. Lather all surfaces of hands for 15 seconds
5. Rinse soap
6. dry hands
7. Turn off taps with paper towel
Needle-Stick Prevention: True or False

Recapping causes more needle-sticks than any other single procedure.
( T )

Dumping needles and syringes with other waste is okay.
( F )

Burning or incinerating is one way to destroy needle disposable boxes. ( T )

Needle boxes should be puncture-proof and used only once.
( T )

It is acceptable to walk around with used equipment
( F )

Always prepare and position young children securely before giving them an injection so they do
not grab needles or kick unexpectedly.
( T )

Needle-stick injuries can occur at anytime during an injection but they occur most frequently
during and immediately after injection.
( T )
38