PGI Microbiology And Immunology Solved Model Question Paper 2023

PGI Microbiology And Immunology Model Question Paper 2023

Question.1. True about microbial sterilization techniques:

1. Kills both vegetative and spore forms of bacteria
2. Kills vegetative but not spore forms of bacteria
3. Can be used only for living surface
4. CO2 can be used for sterilization
5. Water can be disinfected by chlorination

Answer. (1, 4,5) (Kills both forms.., CO2 can be used for sterilization, Water can be disinfected by chlorination)

Read And Learn More: Micro Biology And Immunology Model Question Papers With Answers

• Sterilization kills both vegetative and spore forms of bacteria
• Agents used for sterilization are usually applied for non-living surfaces.
• Antiseptics are used for living surfaces and they are milder disinfectants, cannot achieve sterilization.
• Recently, supercritical carbon dioxide (scCO2) is recently used for terminal sterilization… internet source
• Chlorination is the method of choice for disinfection of drinking water.

Question.2. Secondary lymphoid organ is/are:

1. Spleen
2. Bone marrow
3. Lymph node
4. Liver
5. Mucosa-associated lymphoid tissue (MALT)

Answer. (1, 3, 5) (Spleen, lymph node, MALT)

• Primary lymphoid organs are bone marrow and thymus
• Secondary lymphoid organs are: spleen, lymph node, MALT

Question.3. True about acute graft rejection in organ transplantation:

• Higher mortality & morbidity than hyper-acute graft rejection
• Mainly mediated by anti-HLA antibodies
• Most common cause of graft failure
• Can be reversed by increasing dose of corticosteroid
• Predictor of chronicity

Answer. (3, 4, 5) (Most common cause of graft failure, Can be reversed by increasing dose of corticosteroid, Predictor of chronicity)

• Hyper-acute graft rejection is a more severe condition and is associated with higher mortality and morbidity than acute graft rejection
• Hyper-acute graft rejection is mainly mediated by anti-HLA antibodies; acute graft rejection is mediated by cytotoxic T cell mediated and antibody-mediated
• Acute graft rejection is more common form of graft rejection
• Acute graft rejection can be reversed successfully in 60% when treated with corticosteroid therapy… internet sources

Question.4. Function of suppressor T cells:

1. Prevent reactions against self-antigens
2. Primary function is to suppress immune system
3. Carry CD25 molecule on their surface
4. Stimulate B lymphocytes
5. Kill infected cells

Answer. (1, 2, 3) (Prevent reactions against self-antigens, Primary function is …, Carry CD25 molecule on their surface)

• Treg or T-suppressor cells provide tolerance to self-antigens (known as peripheral tolerance), and thus prevent the development of autoimmune disease
• Surface markers: they possess surface markers such as CD4, CD25, and Foxp3

Question.5. Which of the following is/are example of superantigens?

1. Toxic shock syndrome toxin (TSST)
2. Cholera toxin
3. Group A streptococcal pyrogenic exotoxin
4. Staphylococcal enterotoxins
5. Diphtheria toxin

Answer. (1, 3, 4) (Toxic shock syndrome toxin (TSST), Group A streptococcal pyrogenic exotoxin, Staphylococcal enterotoxins)

Toxic shock syndrome toxin, Group A streptococcal pyrogenic exotoxin and Staphylococcal enterotoxins are examples of superantigens.

Question.6. True about Superantigens:

1. Polyclonal T-lymphocyte activation
2. Releases large amount of cytokines
3. Bind TCRβ and class II MHC molecule
4. Need no processing
5. Require antigen specificity

Answer. (1, 2, 3, 4) (Polyclonal T-lymphocyte activation, Releases large amount of cytokines,

Bind TCRβ and class II MHC molecule, Need no processing)

Superantigens have the unique feature that, they can activate T cells directly without being processed by antigen-presenting cells (APCs).

• The variable β region of T cell receptor (vβ of TCR) appears to be the receptor for superantigens
• They directly bridge non-specifically between MHC-II of APCs and T cells
• Non-specific activation of T cells leads to massive release of cytokines which can activate B cell polyclonally, which leads to increased secretion of non-specific antibodies (hypergammaglobulinemia).

Question.7. Proteus mirabilis is/are intrinsic resistant to which antibiotic (s)?

1. Nitrofurantoin
2. Cephalosporins
3. Tetracycline
4. Ampicillin
5. Ampicillin-salbactam

Answer. (1, 3) (Nitrofurantoin, Tetracycline)

Proteus mirabilis is intrinsically resistant to clindamycin, daptomycin, lincosamides, fusidic acid, glycopeptides (vancomycin, teicoplanin), lipoglycopeptides (oritavancin, telavancin), linezolid, tedizolid, quinupristin-dalfopristin, rifampin, macrolides (erythromycin, clarithromycin, and azithromycin), streptogramines, tetracyclines, tigecycline, polymyxin B, colistin, nitrofurantoin…………. CLSI M100 2020

Question.8. Non-sporing anaerobic bacteria is/are:

1. Peptostreptococcus
2. Propionibacterium
3. Clostridium
4. Anthrax
5. Bacteroides

Answer. (1, 2, 5) (Peptostreptococcus, Propionibacterium, Bacteroides)

• Peptostreptococcus, Propionibacterium, and Bacteroides are non-sporing anaerobes
• Clostridium is spore-bearing anaerobe whereas B.anthracis is obligate aerobe

Question.9. Anaerobic gram-positive bacilli is/are:

1. Actinomyces
   Lactobacillus
   Bacteroides
   Veillonella
   Clostridium

Answer. (1, 2, 5) (Actinomyces, Lactobacillus, Clostridium)

Anaerobic gram-positive bacilli are Bifidobacterium, Eubacterium, Propionibacterium,Lactobacillus, Actinomyces, Mobiluncus and Clostridium.

Question.10. Leprosy is zoonosis in:

1. Nine banded armadillos
2. Nude mice
3. Mangabey monkey
4. Chimpanzee
5. European hedgehog

Answer. (1, 2, 4) (Nine-banded armadillos, Mangabey monkey, Chimpanzee)

• Lepra bacilli can produce natural disease in nine-banded armadillo as well as other susceptible animals such as slender loris, Indian pangolin, chimpanzees, and West African mangabey monkeys
• Lepra bacilli can grow in foot pad of mice, however natural disease has not been documented

Question.11. Which of the following is/are not feature of Weil’s disease?

1. Uveitis
2. Renal failure
3. Jaundice
4. Icterohemorrhagic fever
5. Ecchymosis and petechiae

Answer. (None)

Weil’s disease is characterized by:

• High-grade fever, jaundice, and raised liver enzymes
• Hemorrhagic manifestations such as pulmonary haemorrhage, petechiae, and purpura, conjunctival haemorrhage, gastrointestinal hemorrhage
• Kidney—Raised serum urea and creatinine and renal failure
• Meningitis, uveitis, optic neuritis chorioretinitis are observed in Mild anicteric stage of leptospirosis

Question.12. Match the correct dyads of rickettsial disease with their causative agents:

1. Endemic typhus: R. typhi
2. Rickettsial pox: R. akari fever: Coxiella burnetii
3. Epidemic typhus: R. prowazekii
4. Rocky Mountain spotted fever: Orientia tsutsugamushi

Answer. (1, 2, 3, 4) (Endemic typhus: R. typhi, Rickettsialpox: R. akari, fever: Coxiella burnetii, Epidemic typhus: R. prowazekii)

• Rocky Mountain spotted fever- caused by R. rickettsii
• Orientia tsutsugamushi causes scrub typhus

Question.13. Feature(s) of scrub typhus:

1. Transmitted by rat flea
2. Caused by R. prowazekii
3. Black eschar
4. Doxycycline is used for treatment
5. Rats are the reservoir

Answer. (3, 4, 5) (Black eschar, Doxycycline is used for treatment, Rats are the reservoir)

• Scrub typhus is transmitted by mites, caused by Orientia tsutsugamushi
• Black eschars are characteristic feature of scrub typhus, rickettsial pox, and Indian tick typhus
• Doxycycline is used for treatment for all types of rickettsial infections
• Small mammals (e.g. field mice, rats, shrews), and secondary scrub vegetations are the reservoir for O. tsutsugamushi

Question.14. To screen congenital syphilis, which of the following test(s) is/are done:

1. VDRL
2. Rapid plasma Reagin (RPR)
3. FTA-ABS
4. TPHA
5. Darkfield microscopy

Answer. (1, 3, 5) (VDRL, FTA-ABS, Dark field microscopy)

Diagnosis of congenital syphilis:

• Definitive diagnosis: Demonstration of T. pallidum by DGM of umbilical cord, placenta, nasal discharge, or skin lesion material.
• Presumptive diagnosis:
  • Infant born to a mother who had syphilis at the time of delivery regardless of findings in the infant
  • Reactive treponemal test in infant
  • One of the following additional criteria:
    • Clinical signs/symptoms of congenital syphilis
    • Abnormal CSF findings without other cause
    • Reactive VDRL-CSF test
    • Reactive IgM antibody test specific for syphilis (IgM FTA ABS or IgM ELISA).

Note: As IgM does not cross the placenta, its presence in neonatal serum confirms the diagnosis of congenital syphilis.

Question.15. Non-treponemal test includes:

1. TPHA
2. RPR
3. TPI
4. VDRL
5. FTA-ABS

Answer. (2, 4) (RPR, VDRL)

• TPHA, TPI, FTA-ABS are Treponemal tests, uses specific T.pallidum antigens to detect antibodies
• VDRL and RPR are non-treponemal tests, uses non-specific cardiolipin antigens to detect antibodies

Question.16. Which of the following is/are not feature of chancroid:

1. Caused by H.ducreyi
2. Painful ulcer
3. Ulcer bleeds easily
4. Bubo formation
5. Typically indurated

Answer. (5) (Typically indurated)

Chancroid is caused by Haemophilus ducreyi; characterized by painful soft non-indurated genital ulcers (that bleeds easily if touched) and inguinal lymph nodes (called buboes).

Question.17. Sample for routine anaerobe culture can be taken from:

1. Tissue specimen
2. Blood
3. Vaginal swab
4. Bone marrow
5. Sputum

Answer. (1, 2, 4) (Tissue, blood, Bone marrow)

• Specimens recommended for anaerobic culture- tissue specimens, blood, bone marrow,aspirate or pus in syringes, suprapubic aspirated urine
• Specimens inappropriate for anaerobic culture—voided urine, sputum, swabs, stool (except for C. difficile)

Question.18. New Delhi ambler class B metallo-beta-lactamase (NDM) mediated carbapenem resistance is seen in:

1. Citrobacter freundii
2. E.coli
3. P. aeruginosa
4. K. pneumoniae
5. Acinetobactor baumannii

Answer. (ALL) internet sources

New Delhi metallo-β-lactamase–producing Enterobacteriaceae (Klebsiella pneumoniae,Escherichia coli, Enterobacter cloacae, Salmonella enterica, Citrobacter), Pseudomonas spp., and Acinetobacter baumannii.

Question.19. Which of the following is/are true regarding RNTCP changes:

1. Active case finding
2. Thrice weekly regimen
3. Focus to improve outcome of TB care in the private sector
4. To achieve 90% success rate for all new cases and 85% for retreatment cases
5. Involvement of NGOs

Answer. (1, 3, 4, 5) (Active case finding, Focus to improve outcome of TB care in the private sector, To achieve 90% success rate for all new cases and 85% for retreatment cases, Involvement of NGOs) and National Strategic Plan for Tuberculosis Elimination 2017–2025 by RNTCP.

RNTCP currently daily regimen recommends daily regimen of ATT; rather than thrice weekly regimen. This is to ensure better compliance.

Main strategies of RNTCP are:

• Detecting >70% of estimated cases by quality sputum microscopy
• Cure rate not less than 85%
• Involvement of NGOs (Non-Government Organizations)
• Implementing DOTS (Directly Observed Treatment, Short course)—daily regimen
• Implementing DOTS Plus: For detection and treatment of MDR-TB.

Question.20. True about Gene Xpert:

Rapidly detect Mycobacterium tuberculosis and rifampicin resistance
Use nucleic acid amplification tests (NAAT) technique
Useful to diagnose HIV, hepatitis and TB
Uses real time PCR
Software for gene development

Answer. (1, 2,3,4) (Rapidly detect Mycobacterium tuberculosis and rifampicin resistance, Use nucleic acid amplification tests (NAAT) technique, Useful to diagnose HIV, hepatitis, and TB, Uses real time PCR)

• GeneXpert is a cartridge-based nucleic acid amplification technique (CB-NAAT), based on real-time PCR technology.
• It is widely used for tuberculosis; detects Mycobacterium tuberculosis and rifampicin resistance
• It is also available for other infectious diseases such as detection of Clostridium difficile in stool, viral load estimation for hepatitis B and HIV

Question.21. Both CCR5 & CCR2 receptor antagonist is/are:

1. Maraviroc
2. Vicriviroc
3. Aplaviroc
4. Cenicriviroc
5. None of the above

Answer. (d) (Cenicriviroc)

1. Cenicriviroc is an inhibitor of CCR2 and CCR5 receptors, allowing it to function as an entry inhibitor that prevents the virus from entering into a human cell
2. CCR5 receptor inhibitor- e.g. maraviroc, vicriviroc and aplaviroc

Question.22. True about Cytomegalovirus infection:

1. May be associated with GBS syndrome
2. Ganciclovir and valacyclovir are given for prophylaxis only in immunocompromised patients and not for treatment of symptomatic immunocompetent patients
3. Virus can be isolated from body secretions
4. Severe birth defects may occur
5. Hepatosplenomegaly is the common feature of congenital CMV infection

Answer. (1, 3, 4, 5) (May be associated with GBS syndrome, Virus can be isolated from body secretions, Severe birth defects may occur,
Hepatosplenomegaly is the common feature of congenital CMV infection)

• Guillain-Barré Syndrome may occur due to CMV Reactivation
• Ganciclovir and valacyclovir are the drug of choice for cytomegalic inclusion disease or neonatal CMV infection or for severe CMV infections such as retinitis or transplant infections.
• CMV can be isolated from throat washings and urine. Human fibroblasts are the most ideal cell lines.
• Most common congenital defects are petechiae, hepatosplenomegaly, and jaundice (60–80% of cases).
• However, serious birth defects may also be seen although rare; such as microcephaly,cerebral calcifications, intrauterine growth retardation, and prematurity (30–50% of cases).

Question.23. True about varicella zoster in pregnancy:

1. Congenital anomalies are more common when the infection occurs during 12-20 weeks of gestation
2. Congenital anomalies are more common when the infection occurs after 20 weeks of gestation
3. Immunoglobulins can be given to the neonates whose mother had varicella 5 days before to 2 days after the delivery
4. Acyclovir is unsafe in pregnancy
5. Varicella vaccine is given in pregnancy

Answer. (a, c) (Congenital anomalies are more common when the infection occurs during 12-20 weeks of gestation, Immunoglobulins can be given to the neonates whose mother had varicella 5 days before to 2 days after the delivery)

• Congenital anomalies are more common when the Varicella infection occurs early in the gestation (13–20 weeks of gestation)
• If mother develops chickenpox 5 days before to 2 days after the delivery—leads to dissemination neonatal varicella (a severe form of chickenpox). Immunoglobulins are the treatment of choice in this condition.
• Use of acyclovir in the first trimester does not increase birth defects, and it should be the antiviral drug of choice in early pregnancy……internet sources
• Varicella vaccine is a live attenuated vaccine and therefore is not recommended in pregnancy

Question.24. Following is true regarding immunoprophylaxis of Hepatitis B in pregnancy:

1. A combination of hepatitis B immune globulin (HBIG) and hepatitis B vaccination should be initiated within 12 hours of delivery
2. In mothers with an unknown HBsAg positivity status at delivery, the birth dose of hepatitis B vaccine can be delayed up to >24 hours of birth
3. In the case of preterm babies of HBsAg-positive mothers, the birth dose is indicated only if the baby weighs more than 2 kilograms
4. 4 doses of vaccine should be given postnatally

Answer. (1, 4) (A combination of hepatitis B immune globulin (HBIG) and hepatitis B vaccination should be initiated within 12 hours of delivery, 4 doses of vaccine should be given postnatally)

• Universal screening of pregnant women for HBsAg during each pregnancy is mandatory.
• Screening of all HBsAg-positive pregnant women for HBV DNA. Maternal antiviral therapy is indicated when HBV DNA is >200,000 IU/mL.
• Provision of immunoprophylaxis for infants born to infected mothers, including hepatitis B vaccine (1st dose) and hepatitis B immune globulin within 12 hours of birth; followed by full course of vaccine series (three doses of pentavalent vaccine containing combination of DPT, hepatitis B and H.influenzae type b vaccines.; given at 6 weeks,10 weeks and 14 weeks); hence total of 4 doses of vaccine should be given postnatally.

Question.25. For extensive tinea infection in pregnancy, which of the following antifungal drug can he used:

1. Terbinafine
2. Fluconazole
3. Lamivudine
4. Griseofulvin
5. Itraconazole

Answer. (1) (Terbinafine)

Oral terbinafine is the drug of choice for treatment of dermatophytosis in pregnancy.

Azoles may be teratogenic, therefore should be avoided in pregnancy, especially first trimester.

Question.26. All are true about kala-azar except:

1. Transmitted by female sand fly
2. Endemic in African
3. Rapid diagnostic kit is available
4. Indian kala-azar is a zoonotic disease

Answer. (4) (Indian kala-azar is a zoonotic disease)

• Leishmaniasis is transmitted by Sand-fly
• Leishmaniasis is endemic in India as well as in East Africa
• Rapid diagnostic kit is available- ICT detecting antibodies against rk39 antigen
• Indian kala-azar is exclusively human (Anthroponotic), not zoonotic.
• Leishmaniasis is zoonotic in Middle East, Africa and China, Mediterranean, and Central Asia

Question.27. False about methods used for Disinfecting/Sterilizing Milk:

1. Methylene blue test is used to detect microorganisms in milk
2. Phosphatase test is used to detect the efficiency of pasteurization
3. Pasteurization kills 100% bacteria
4. Milk is heated to 135 degree in ultra-high temperature method

Answer. (3) (Pasteurization kills 100% bacteria)

• Methylene blue reduction test is used to detect microorganism in milk
• In pasteurization: Milk is heated to high temperature for short time (72°C for 15 seconds). Efficacy of pasteurization is tested by the phosphatase test.
• Ultra-heat treated milk: The milk is exposed to very high temperature of 135°C for 1 second so that all microorganisms with their spores are destroyed.

Question.28. True about Category A bioweapon agents except:

1. May cause life-threatening infection
2. Easily transmitted from person to person
3. Potential for major public health impact
4. Brucellosis is an example
5. Require special action for public health preparedness

Answer. (4) (Brucellosis is an example)

Brucellosis is category B bioweapon

Category A bioweapons: These agents are the highest priority pathogens which pose the greatest risk to national security

• These agents can be easily disseminated or transmitted from person to person
• Result in high mortality and have the potential for major public health impact
• Might cause public panic and social disruption
• Require special action for public health preparedness

Question.29. Maximum accepted contamination rate for a blood culture is:

1. 1%
2. 2%
3. 3%
4. 6%
5. 10%

Answer. (3) (3%)

Maximum accepted contamination rate for a blood culture is 3%.