AIIMS Microbiology And Immunology Solved Model Question Paper Nov 2022

AIIMS Microbiology And Immunology Model Question Paper Nov 2022

 

Question 1. In which of the following ways is CLED medium better than MacConkey agar?

1. It prevents proteus swarming
2. Inhibits growth of other commensals
3. It allows Staphylococcus and Candida to grow
4. It differentiates lactose fermenters from non-fermenters

Answer.3.(It allows Staphylococcus and Candida to grow)

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

• Advantage of CLED agar over MacConkey agar is that it allows S.aureus and yeast (Candida) to grow, whereas MacConkey agar may contain inhibitory substances which inhibit gram-positive bacteria such as S. aureus and yeast (Candida) to grow.
• Advantage of CLED agar over blood agar is that it prevents Proteus swarming.

Question 2. Which of the following is true about γδ-T cells?

1. It resides in gastrointestinal tract epithelium
2. It is a type of T-helper cells
3. Requires MHC for antigen-presentation
4. It shows direct cytotoxicity

Answer. (1) (It resides in gastrointestinal tract epithelium)

γδ T cells represent a small subset of T cells (5%) that possess a distinct TCR composed of γ and δ chains; instead of α/β chains. They differ from the conventional αβ T cells by:

• They lack both CD4 and CD8 molecules, therefore they are neither similar to T helper cells, nor cytotoxic T cells
• They do not require antigen processing and MHC presentation of peptides
• They are part of innate immunity as the γδ receptors exhibit limited diversity for the antigen
• They are usually found in the gut mucosa, within a population of lymphocytes known as intraepithelial lymphocytes (IELs)
• The function of γδ T cells is not known, they may encounter the lipid antigens that enter through the intestinal mucosa.

Question 3. Which is not involved in SCID?

1. ADA
2. IL2R
3. JAK3
4. BTK

Answer. (4) (BTK)

• Severe combined immunodeficiency (SCID) is a group of rare disorders caused by mutations in different genes resulting in defect in immune system such as (1) cytokine receptor such as IL7 or IL2, (2) ADA (Adenosine deaminase), (3) RAG (recombinase activator gene), (4) Jak3 mutation (intracellular kinase)
• Bruton tyrosine kinase (BTK) gene mutation leads to Bruton X-linked agammaglobulinemia.

Question 4. Assertion: Anaphylactoid reaction can be caused by 1st exposure.
Reasons: Involves mast cell degranulation, without IgE activation:

1. Both Assertion and Reasons are independently true/correct statements and the Reason is the correct explanation for the Assertion.
2. Both Assertion and Reasons are independently true/correct statements, but the Reason is not the correct explanation for the Assertion
3. Assertion is independently a true/correct statement, but the Reasons is independently false/incorrect statement
4. Assertion is independently a false/incorrect statement, but the Reasons is independently true/correct statement
5. Both Assertion and Reasons are independently false/incorrect statements

Answer. (2) (Both Assertion and Reasons are independently true/correct statements, but the Reason is not correct explanation for the Assertion)Internet sources

Anaphylactoid reactions are defined as those reactions that produce the same clinical picture with anaphylaxis but are not IgE mediated, occur through a direct nonimmune-mediated release of mediators from mast cells and/or basophils or result from direct complement activation.

• Prior sensitization by the antigen is not necessary
• Most commonly caused by NSAIDs and radiocontrast media
• It can occur on first exposure without IgE activation
• Not hypersensitivity reaction

Question 5. Pulmonary manifestation for inhalational anthrax is:

• Hemorrhagic mediastinitis
• Lung abscess
• Bronchopulmonary pneumonia
• Atypical pneumonia

Answer. (1) (Hemorrhagic mediastinitis)

Pulmonary anthrax is presented as hemorrhagic mediastinitis, which may lead to hemorrhagic meningitis and bacteremia.

Question 6. Giemsa stain of peripheral blood smear is not useful in infection of which of the following?

1. Coxiella burnetii
2. Bartonella bacilliformis
3. Toxoplasma gondii
4. Ehrlichia chaffeensis

Answer. (1) (Coxiella burnetii)

• The diagnosis of Coxiella burnetii cannot be made using Giemsa stain of peripheral blood smear. It is usually diagnosed by serology detecting specific antibodies in patient’s serum.
• The other options: Bartonella, Toxoplasma (tachyzoites) and Ehrlichia can be detected by peripheral blood smear examination.

Question 7. A 25 years old man presents with urethral discharge for the last three days. A Gramstained smear of the discharge is shown in the figure. All of the following are true about the likely etiological agent except:

1. Pili is a virulence factor
2. Obligate intracellular
3. Show twitching motility
4. Catalase and oxidase positive

Answer. (2) (Obligate intracellular)

Gonococcus is facultative intracellular, not obligate intracellular

Gram staining of urethral exudates reveals gram-negative intracellular kidney-shaped diplococcic; suggestive of gonococcal urethritis.

• Pili are the principle virulence factor of Neisseria gonorrhoeae
• Twitching motility is a form of crawling bacterial motility used to move over surfaces;mediated by hair-like filaments called type IV pili. The name twitching motility is derived from the characteristic jerky and irregular motions of individual cells when viewed under the microscope. It has been observed in many bacterial species, but is most well studied in Pseudomonas aeruginosa, Neisseria gonorrhoeae and
  Myxococcus xanthus….……(Internet source).
• Neisseria gonorrhoeae is catalase and oxidase positive.

Question 8. Mechanism of action of the toxin produced by the bacterium shown in the figure:

1. Increase in cAMP
2. Increase in cGMP
3. ADP-ribosylation of EF2
4. ADP-ribosylation of G protein

Answer. (3) (ADP-ribosylation of EF2)

• The given picture shows club shaped gram-positive bacilli, arranged in cuneiform or Chinese letter pattern…… suggestive of Corynebacterium diphtheriae
• The mechanism of action of diphtheria toxin is ADP ribosylation of elongation factor-2,leading to inhibition of protein synthesis.

Question 9. Which of the following produces toxin that acts by the mechanism shown in the figure?

1. Clostridium tetani
2. Clostridium botulinum
3. Clostridium perfringens
4. Corynebacterium diphtheriae

Answer. (2) (Clostridium botulinum)

L chain of botulinum toxin causes proteolysis of the target SNARE proteins (soluble-Nethyl maleimide-sensitive factor attachment protein) in the neurons—leads to inhibition the release of acetylcholine at the synapse, resulting in lack of muscle contraction and paralysis.

Question 10. Drug of choice for bacterial vaginosis in pregnancy is:

1. Clindamycin
2. Metronidazole
3. Erythromycin
4. Rovamycin

Answer. (2) (Metronidazole)

• Approximately 10–30% of pregnant women can experience bacterial vaginosis during their pregnancy.
• Metronidazole (oral or vaginal cream) is drug of choice for bacterial vaginosis including in pregnancy.

Question 11. A 26 years old female presents with foul smelling greyish-white discharge, diagnosed to be Gardnerella vaginalis infection. Microscopic findings are suggestive of:

1. Group of bacilli arranged in chain forms
2. Bacteria found to be engulfed by macrophages
3. Bacteria adherent to lining vaginal epithelial cells
4. Bacteria arranged in cluster forms

Answer. (3) (Bacteria adherent to lining vaginal epithelial cells)
Clue cells are pathognomic feature of bacterial vaginosis (caused by Gardnerella vaginalis); characterized by vaginal epithelial cells coated with coccobacilli, which have a granular appearance and indistinct borders observed on a wet mount.

Question 12. Treatment of Pauci-bacillary leprosy as per WHO guidelines:

1. 2 drugs for 12 months
2. 3 drugs for 12 months
3. 2 drugs for 6 months
4. 3 drugs for 6 months

Answer. (4) (3 drugs for 6 months)
Microbiology 2/e p302; WHO Leprosy guideline 2018

• WHO guideline recommend a 3-drug regimen of rifampicin, dapsone and clofazimine for all leprosy patients, with a duration of treatment of 6 months for PB leprosy and 12 months for MB leprosy.
  • This represents a change from the current standard treatment for PB leprosy, which is rifampicin and dapsone for 6 months, due to some evidence indicating better clinical outcomes with a 3-drug, 6-month regimen over a 2-drug, 6-month regimen.
  • A potential advantage of using the same three drugs for PB and MB leprosy is simplification of treatment (i.e. the same blister pack could be used for treating both types of leprosy) and reduced impact of misclassification of MB leprosy as PB leprosy, since all patients will receive a 3-drug regimen.
• However, as per National Leprosy Eradication Programme 2019 guideline, 2 drug regimen (rifampicin + dapsone) is still recommended for paucibacillary leprosy.

Question 13. Pneumococcal vaccine will be most beneficial for which of the following groups?

1. Cystic fibrosis patient
2. Sickle cell anemia
3. Recurrent otitis and sinusitis
4. Child less than 2 years

Answer. (2) (Sickle cell anemia)
Indications for pneumococcal vaccine include:

• After birth (as a part of routine childhood immunization)
• Age ≥65 years
• Age 19–64 years with underlying risk factors
  • Immunocompetent persons: With alcoholism and smoking, chronic heart, liver and lung disease, diabetes mellitus
  • Immunocompetent persons: With cochlear implants and CSF leaks
  • Splenic dysfunction: Congenital or acquired asplenia, sickle cell disease/other hemoglobinopathies
  • Immunocompromised persons: Chronic renal failure, congenital or acquired immunodeficiencies, HIV infection, malignancy and solid organ transplant

Question 14. Mark the following statements as true or false regarding antivirals:

• Treatment of HCV with ribavirin is considered superior to sofosbuvir therapy
• Ombitasvir prevents HCV protein synthesis
• Imiquimod used in treatment of condyloma acuminata
• Simprevir inhibits protease of hepatitis C
• Oseltamivir is used for H1N1 flu

Answer. (a-F, b-T, c-T, d-T, e-T)

• Treatment of HCV: Directly acting antiviral agents (e.g. sofosbuvir) are considered superior to conventional therapy with ribavirin and
  interferon………. Ref: Apurba Sastry’s EssMicro 2/e p562
• Ombitasvir prevents HCV protein synthesis
• Imiquimod is an interferon inducer, used for treatment of condyloma acuminata
• Simprevir is NS3/4a (protease) inhibitor, used as directly acting antiviral agent for treatment of HCV
• Oseltamivir is neuraminidase inhibitor, considered as DOC for treatment of H1N1 flu.

Question 15. Match the following:

1-A; 2-C; 3-B; 4-D
1-A; 2-D; 3-B; 4-E
1-C; 2-A; 3-D; 4-B
1-A; 2-C; 3-D; 4-B

Answer. (4) (1-A, 2-C, 3-D, 4-B)

• Molluscum bodies, also called as Henderson-Paterson bodies—seen in Molluscum contagiosum infection
• Owl’s eye inclusion bodies seen in CMV infection
• Koilocytes, also known as halo cells, are a type of epithelial cell that develops following HPV infection
• Decoy cells are virally infected epithelial cells that can be found in the urine; e.g.cytomegalovirus and Polyomavirus.

Question 16. For influenza virus, which of the following is not true?

1. Secondary attack rate is 5 to 15%
2. Virus shedding present before the patient presents with symptoms
3. 1 to 5 years is not a high-risk age group
4. Aquatic birds are reservoir

Answer. (3) (1 to 5 years is not a high-risk age group)

• The attack rate is 5–15 years in adult and 20–30% in children
• Period of infectivity is 1–2 days before and 1–2 days after onset of symptoms
• Infants and younger children (6 months Answer.5 years) are considered as high risk group for influenza
• Birds and animals such as pigs are the usual reservoir for influenza

Question 17. A child who has previously received complete dose of rabies vaccination in December 2018 and now presented to OPD (Nov 2019) with history of dog bite by his pet dog which had received complete rabies immunization. What is the next line of management?

1. No vaccination required
2. Rabies immunoglobulin administration + 5 doses of vaccination
3. Rabies vaccine 5 doses at 0, 3, 7, 28 and 90 days
4. Rabies vaccine at single site, two doses on day 0 and 3

Answer. (4) (Rabies vaccine at single site, two doses on day 0 and 3)

Regimen for post-exposure Prophylaxis in previously vaccinated individuals, depends on the antibody titer and the severity of the wound bite.

• Severe bite or titer unknown: 3 doses are given on—0, 3 and 7 days
• Less severe bite or titer >0.5 IU/mL: 2 doses given on 0 and 3 days
• Immunoglobulins are usually not needed.

In this question, the post-vaccination titre for the person as well as pet dog and the severity
of bite is not mentioned. Therefore, option-d is best possible answer.

Question 18. What is the mainstay of treatment of dengue with warning signs?

1. Platelet transfusion
2. IV fluids
3. Steroids
4. Antibiotics

Answer. (5) (IV fluids)
The main pathology in dengue with warning sign is plasma leakage resulting in intravascular fluid loss and thereby shock. Therefore, the mainstay of treatment of dengue is continuous infusion of crystalloid IV fluid.

Question 19. Criteria to discharge a patient for dengue hemorrhagic fever include:

• Urine output >200 mL
• Fever controlled on paracetamol for >24 hours
• Return of appetite
• 24 hours after recovery from shock

Answer. (4) (24 hours after recovery from shock)

According to National Vector Borne Disease Control Programme (NVBDCP), India,the criteria of discharge of patient with dengue include:

• Absence of fever for at least 24 hours without the use of anti-fever therapy
• Return of appetite
• Visible clinical improvement
• Good urine output
• Minimum of three days after recovery from shock
• No respiratory distress from pleural effusion and no ascites
• Platelet count of more than 50,000/mm3

Question 20. Patient of hepatitis B recovered from infection. Name the serological maker marked in arrow in image:

1. Anti-HBc antibody
2. Anti-HBs antibody
3. HBsAg
4. HBeAg

Answer. (a) (Anti-HBc antibody)

• Line-1: HBsAg and Line-5 anti-HBs antibody
• Line-2: Anti-HBc antibody (marked in arrow)
• Line-3 HBeAg and line-4 is anti-HBeAb

Question 21. All of the following infections present with morbilliform rashes except:

1. Dengue
2. Rubella
3. Herpes zoster
4. Measles

Answer. (3) (Herpes zoster)

• The term morbilliform refers to a rash that looks like measles; described as rose-red flat (macular) or slightly elevated (maculopapular) eruption, showing circular or elliptical lesions varying in diameter from 1 to 3 mm, with healthy-looking skin intervening.
• Apart from measles, it is observed Kawasaki disease, meningococcal petechiae or Waterhouse-Friderichsen syndrome, Dengue, Roseola, congenital syphilis, rubella,Echovirus, drug hypersensitivity reactions (e.g. antiretroviral drugs, such as abacavir and nevirapine, and also the antiepileptic drug phenytoin).

Question 22. True/false regarding SSPE:

1. Characterized by seizure
2. Most common cause of herpes zoster
3. EEG is characterized by slow periodic sharp waves
4. Usually happens 7–12 years after an attack of measles
5. Serum anti-measles antibodies may be normal in the patient

Answer. (a-T, b-F, c-T, d-T, e-F)

Subacute sclerosing panencephalitis (SSPE)

• It is a slowly progressive disease characterized by seizures and progressive deterioration of cognitive and motor functions
• SSPE typically develops if the primary measles virus infection, not herpes zoster
• SSPE usually develops after 7–13 years after primary measles infection.
• High titers of antibody to measles virus in CSF is diagnostic of SSPE.
• The characteristic EEG pattern consists of high-voltage (300–1500 µV), repetitive,polyphasic sharp and slow wave complexes of 0.5- to 2-second duration that recur every 4–15 seconds.

Question 23. Which of the following is the most common cause of infection in post-solid organ transplant recipients in an Indian setting?

1. Varicella
2. EBV
3. CMV
4. Herpes simplex

Answer. (3) (CMV)

1. CMV is probably the most common viral infection that occurs in transplant recipients.
2. Infection occurs usually between 1 and 4 months following transplantation and presents in various forms; most common being bilateral interstitial pneumonia.

Question 24. A 16 years unmarried girl, came for vaccination against cervical cancer. Which of the following vaccine has to be given?

1. Gardasil
2. Rabivac
3. Biovac
4. Tvac

Answer. (1) (Gardasil)

Gardasil (9 valent) and cervarix (bivalent) are the vaccines available commercially for prevention of cervical cancer due to HPV infection.

Question 25. 1, 3-beta-D-glucan assay is done for all except:

1. Invasive aspergillosis
2. Pneumocystis jiroveci
3. Candidiasis
4. Mucormycosis

Answer. (4) (Mucormycosis)

• Beta-1,3-D-glucan assay detects the presence of 1,3-beta-D-glucan component of fungal cell wall. It is present in most of the cell wall except mucormycosis, cryptococcosis,and Blastomyces
• Galactomannan assay is diagnostic for invasive aspergillosis

Question 26. A 10 years old child presents with bald patch on the scalp with easy pluckable of hair. Magnifying glass examination shows black spots on the hair loss area. Drug of choice for the given condition is:

1. Griseofulvin
2. Ivermectin
3. Fluconazole
4. Amphotericin B

Answer. (1) (Griseofulvin)

Harrison 20th/p1546

Oral terbinafine or itraconazole are the drugs of choice for treatment of dermatophytosis.

Oral griseofulvin can be given alternative.

Question 27. All of the following are found intracellularly inside hepatocytes, except:

1. Plasmodium
2. Leishmania
3. Babesia
4. Toxoplasma

Answer. (3 (Babesia)

• Parasites that are found intracellularly inside hepatocyte are Plasmodium, Leishmania and Toxoplasma
• Babesia do not have a hepatic cycle. They directly infect RBCs

Question 28. Which of the following is transmitted by the vector shown in the figure?

1. Kyasanur forest disease
2. Orientia tsutsugamushi
3. Chandipur virus
4. Anaplasma phagocytophila

Answer. (2) (Orientia tsutsugamushi)

• The vector in the given picture is trombiculid mite because it contains four pairs of legs.
• The body is not well demarcated into three parts (head, thorax and abdomen)
• Diseases transmitted by trombiculid mite—scrub typhus, agent is
• Orientia tsutsugamushi.

Question 29. Maltese cross form seen in:

1. Cryptococcus
2. Babesiosis
3. Pneumocystis jirovecii
4. Leishmaniasis

Answer. (2) (Babesiosis)Demonstration of two or four rings of 1–5 µm size inside the RBCs (called as Maltese cross forms) is characteristic feature seen in babesiosis.

Question 30. Which of the following organism causes multiple alveolar like mass in liver?

1. Echinococcus granulosus
2. Echinococcus multilocularis
3. Amoebic liver abscess
4. Cysticercus cellulosae

Answer. (2) (Echinococcus multilocularis)

Echinococcus multilocularis causes polycystic hydatid disease, characterized by presence of multiple locules in the hydatid cyst resembling avleoli; the most common site being liver.

Question 31. Intensified control phase under the national framework for malaria elimination is defined as:

1. States with API ≥2
2. Zero incidence of malaria
3. No longer a health problem
4. 3 consecutive years no local transmission in the state

Answer. (1) (States with API ≥2)

National Framework for Malaria Elimination (NFME) in 2016 with vision of malaria elimination by 2030. In 2015, all the districts of India are stratified into four categories based on annual parasite incidence (API).

• Category 0 (Prevention of re-establishment phase): Includes districts historically considered to be without local transmission and reporting no case for last 3 years.
• Category 1 (Pre-elimination phase): Includes districts having API <1/1,000 population
• Category 2 (Elimination phase): Includes districts having API ≥1 to ≤2/1,000 population
• Category 3 (Intensified control phase): Includes districts having API >2/1,000 population

Question 32. A nurse got accidental prick from the HIV infected needle. Which of the following is false regarding the management of this nurse?

1. Zidovudine is used as monotherapy in post-exposure prophylaxis
2. Washing hands with soap and water is advised
3. Baseline viral markers of healthcare personnel should be done at the time of prick
4. Follow-up viral markers of healthcare personnel should be measured at 6 weeks

Answer. (1) (Zidovudine is used as monotherapy in post-exposure prophylaxis)

• PEP regimen for HIV include tenofovir, lamivudine and efavirenz (TLE)
• The first dose need to be given within 2 hours of exposure
• If source found to be positive or unknown, the PEP need to be continued for 28 days
• HCW should be tested for viral markers (HBsAg, HCV and HIV) at baseline (time of exposure) and follow-up 6 weeks, 3 months and 6 months after exposure

Question 33. Coloured dustbins Biomedical waste (match the following):

1. 1-A; 2-B; 3-C; 4-D
2. 1-B; 2-E; 3-D; 4-C
3. 1-B; 2-A; 3-D; 4-C
4. 1-B; 2-C; 3-D; 4-E

Answer. (3) (1-B; 2-A; 3-D; 4-C)

• Catheters are plastics, must be segregated in red bags
• Torn registration forms are general waste, segregated in general waste container. There is no general rule framed by government of India for the color of general waste container.
  Various hospitals use different color, most common being green and black.
• Expired vaccine must be segregated in yellow bags
• Antibiotic bottles are glass in nature and therefore segregated in blue containers

Question 34. A study is to be designed to understand the correct technique for injection by a health care professional. The best way to assess will be:

1. In depth interview with the patient
2. In depth interview with the healthcare provider
3. CCTV camera monitoring
4. Structured observation and checklist

Answer. (4) (Structured observation and checklist)
Correct technique for injection can be best assessed by structured observation and checklist. It involves direct observation of the injection practice through use of a structured checklist

• Interview of patient is less effective as patient would not be knowing the correct technique
• Interview of HCWs is also less effective as it assesses the knowledge, not the practice or attitude regarding technique for injection
• CCTV camera though is more effective, it is impractical and has ethical issues

Question 35. Rearrange the sequence of hand washing:

Answer. ( a→ c→ d→ b)

1. WHO Sequence of steps of hand hygiene
   Palm to palm → back to palm → interlaces → back of fingers on palm → thumbs → nail scrubbing on palm

Miscellaneous And Infective Syndrome

Question 36. Assertion: In a patient admitted in hospital for community-acquired pneumonia,combination therapy of beta-lactams and azithromycin is given.
Reason: This combination covers Gram-positive organisms and anaerobes:

1. Both assertion and reason are true and the reason is the correct explanation for the assertion
2. Both assertion and reason are true, but the reason is not the correct explanation for the assertion
3. Assertion is true, but the reason is false
4. Both assertion and reason are false
5. The assertion is false but reason is true

Answer. (3) (Assertion is true, but the reason is false)

• In community-acquired pneumonia, combination therapy of beta-lactams and azithromycin is given
• Beta-lactams are used to cover gram-positives like pneumococcus, and azithromycin to cover atypical agents such as Mycoplasma or Chlamydia or Legionella.

Question 37. Assertion: WHO recommends Typhoid vaccine for disaster management in endemic areas.
Reason: Vaccination is a cost-effective measure of disaster control:

1. Both assertion and reason are true and the reason is the correct explanation for the assertion
2. Both assertion and reason are true, but the reason is not the correct explanation for the assertion
3. Assertion is true, but the reason is false
4. Both assertion and reason are false
5. The assertion is false but reason is true

Answer. (4) (Both assertion and reason are false)

Typhoid vaccine is not recommended for disaster management in endemic areas, as it only offers low, short-term individual protection and little or no protection against the spread of disease.

WHO vaccine recommendations during emergencies

• The only vaccines consistently recommended in disaster management are—measles, and polio
• Vaccines recommended only after the outset of an outbreak: hepatitis A; meningococcal meningitis; and yellow fever
• Vaccines for tetanus, pertussis, and diphtheria are generally not recommended for mass vaccination campaigns, and rather should be implemented through routine immunization programs when conditions stabilize.
• Influenza and typhoid vaccines are generally not recommended at all during emergencies, regardless of the phase
• Cholera is not recommended after the start of an outbreak.