DEPARTMENT OF MICROBIOLOGY
III-B.SC., MICROBIOLOGY- MEDICAL BACTERIOLOGY
CYCLE TEST-II
Paper
Code: 17UMB0 Max
Time: 45 Min
Date: .07.2019 Max Marks: 25
SECTION-A
I.
Answer all the following questions 5X2=10
1. How would you
define the epidemic, pandemic and opportunistic infection?
2. What can you
say about exotoxins and endotoxin?
3. Can you explain the “SSSS” and toxic
shock syndrome?
4. What is meant
by streptolysin and Quellung reaction?
5. Based on what
you know, how would you describe the Meningococcemia?
SECTION-B
II. Answer the following questions 1x5=5
6. How would you
describe the pathogenesis
and lab diagnosis of Neisseria
gonorrhoea?
SECTION-C
III. Answer the following 1x10=10
7.
Can you describe in detail about S.
pyogenes?
DEPARTMENT OF MICROBIOLOGY
III-B.SC., MICROBIOLOGY- MEDICAL BACTERIOLOGY
CYCLE TEST-II
Paper
Code: 17UMB0 Max
Time: 45 Min
Date: .07.2019 Max
Marks: 25
SECTION-A
I.
Answer all the following questions 5X2=10
1. How would you
define the epidemic, pandemic and opportunistic infection?
2. What can you
say about exotoxins and endotoxin?
3. Can you explain the “SSSS” and toxic
shock syndrome?
4. What is meant
by streptolysin and Quellung reaction?
5. Based on what
you know, how would you describe the Meningococcemia?
SECTION-B
II. Answer the following questions 1x5=5
6. How would you
describe the pathogenesis
and lab diagnosis of Neisseria
gonorrhoea?
SECTION-C
III. Answer the following 1x10=10
7.
Can you describe in detail about S.
pyogenes?
KEY POINTS
SECTION-A
1.
Epidemic: disease that attacks at
same time, several communities.
Pandemic: epidemic spreads-throughout
the world.
Opportunistic infection: Normal
flora cause disease, weakened immune system
2. Exotoxins:
two subunits.
·
Fragment
B - binds to the host cell receptor, fragment A to enter the cell
·
enterotoxins.
form toxoids. [Ex.] Neurotoxin, Enterotoxin, Erythrogenic toxin
(ii)
Endotoxins
·
lipopolysaccharides,
cell wall of many gram-negative bacteria. toxic effects - lipid A
·
do
not form toxoids. causes- pyrogenicity, Blood changes, Shock
3.
“SSSS”
- Exfoliative toxin, cause
desquamation of staphylococcal scalded skin syndrome. Specific Toxic shock syndrome toxin
staphylococci, resembles enterotoxin-F and exotoxin-C.
cause fever, shock, skin rash, etc.
4.
Streptolysin
Hemolysins: two
types:
a.
Streptolysin O oxygen labile, heat labile, strongly antigenic,
important in virulence
b.
Streptolysin S is oxygen labile, nonantigenic, nephrotoxic.
Quellung
reaction- Capsular
swelling reaction, mix with type specific antiserum-capsule becomes apparently
swollen
5. Meningococcemia-
acute fever with chills and malaise, Hemorrhagic manifestation.
·
petechial
rash -due to thrombosis, perivascular infiltration and petechial hemorrhage.
SECTION
B
6. Pathogenesis
and lab diagnosis of Neisseria
gonorrhoeae
Morphology:
coccus is Gram-negative, bean shaped
Cultural
characters: It is aerobic, 37°C and at pH 7.4.
Pathogenicity:
venereal disease called gonorrhea. Incubation period is 2 to 8 days.
·
Male -acute
urethritis with mucopurulent discharge containing gonococci-Infection extend
along urethra to prostrate, seminal vesicle and epididymis.
·
Females infection-
urethra and cervix uteri-spread to Bartholin glands, endometrium and fallopian
tubes.
·
Proctitis
occurs in both sexes. Pharyngitis and conjunctivitis, pyelonephritis,
meningitis and pyemia, Ophthalmia neonatorum-newborn-infection from genital
tract of mother.
Laboratory
Diagnosis
a.
Hematological investigations: b. Bacteriological examination: Smear
examination: Gram-negative diplococci inside polymorphs. Culture: blood agar, Stuart transport
medium, Thayer-Martin medium. Serological
test: 1. (CFT) 2. Flocculation test:
RIA and ELISA. NA probe
Treatment:
Sulfonamides and penicillin, tetracycline or erythromycin, spectinomycin,
trimethoprim sulfamethoxazole or cefoxitin.
SECTION-C
7. Streptococcus pyogenes
Morphology:
arranged in chain, encapsulated, non-sporing
and non-motile.
Cultural
character:
aerobic and facultative anaerobes, 37°C. blood, serum, favors rapid growth.
a.
Fluid media: powdery deposits. no pellicle formation. b. Blood agar: (pin point colonies), Selective media: Blood agar medium
having crystal violet
Biochemical
reactions:ferments
lact, gluc, mal-acid but no gas. It is catalase negative.
Antigenic
structure:
Polysaccharide C, M, T, R antigen,
Nucleoproteins
Toxin
Production-1. Hemolysins: a. Streptolysin O & S 2.
Erythrogenic toxin-scarlet fever.
3. Streptokinase (fibrinolysin)-lysis of human fibrin clots 4. Deoxyribonucleases (streptodornase) depolymerization of DNA. 5. Diphosphopyricine nucleotidase (DPNase) 6. Hyaluronidase breaks down hyaluronic acid of tissue. 7. Protease
3. Streptokinase (fibrinolysin)-lysis of human fibrin clots 4. Deoxyribonucleases (streptodornase) depolymerization of DNA. 5. Diphosphopyricine nucleotidase (DPNase) 6. Hyaluronidase breaks down hyaluronic acid of tissue. 7. Protease
Pathogenecity:
1.
Respiratory infection: sore throat, tonsillitis, pharyngitis.
Scarlet fever, otitis media, mastoiditis, Ludwig angina and suppurative
adenitis
2.
Skin infection: suppurative infection of skin, lead- septicemia.
glomerulonephritis
3.
Genital tract: cause of puerperal sepsis. source-nasopharynx-
doctors, nurses and attendants
4. Other
infections-abscess of organs (brain, lungs, liver, kidney), cause
septicemia and pyemia.
5.
Non-suppurative complications: Acute rheumatic fever:
nonsuppurative inflammatory condition, fever, pancarditis, migratory
polyarthritis Acute glomerulonephritis:
nephritogenic strain, impetigo to nephritis.
Laboratory
Diagnosis
1.
Hematological investigations:
2.
Bacteriological method: throat swab, nasopharyngeal swab, pus,
sputum, CSF, blood, etc.
Smear-Gram
positive cocci arranged in chains. Culture:
blood agar or crystal violet blood agar, bacitracin sensitivity test. Serological test: antibody titer
3.
Skin test (Dick test) erythrogenic toxin -intradermally on
forearm and inactivated toxin on other forearm- bright red rash appears
Schultz-Charlton
reaction:
intradermally-scarlatinal rash.
Treatment:
penicillin, sulphonamide, Antitoxic serum
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