DEPARTMENT OF MICROBIOLOGY III-B.SC., MICROBIOLOGY- MEDICAL BACTERIOLOGY CYCLE TEST-II

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

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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