Question 1

Incubation period of mumps is?

Accepted Answer

Answer reason: Mumps (a paramyxovirus infection) has an incubation period typically 16–18 days; among the options, 18 days is correct.

Question 2

Chikungunya is transmitted by?

Accepted Answer

Answer reason: Chikungunya virus is spread to humans by Aedes mosquitoes, primarily Aedes aegypti (also A. albopictus), not Culex, houseflies, or Anopheles.

Question 3

What causes syphilis?

Accepted Answer

Answer reason: Syphilis is caused by the spirochete bacterium Treponema pallidum; the other options cause different diseases (e.g., typhoid, influenza, or are unrelated).

Question 4

What causes malaria?

Accepted Answer

Answer reason: Malaria is caused by Plasmodium species, which are protozoan parasites transmitted by Anopheles mosquitoes.

Question 5

The Widal test is used for the diagnosis of what?

Accepted Answer

Answer reason: The Widal test detects agglutinating antibodies against Salmonella typhi/paratyphi and is used to diagnose enteric (typhoid) fever.

Question 6

Oral polio vaccine was detected?

Accepted Answer

Answer reason: Albert Sabin developed the oral polio vaccine (OPV); Jonas Salk developed the inactivated injectable vaccine.

Question 7

The time interval between a primary and a secondary case is known as?

Accepted Answer

Answer reason: The serial interval is the time between symptom onset in a primary case and symptom onset in a secondary case. Intrinsic/extrinsic incubation periods refer to host/vector incubation, and the window period is time from infection to detectability.

Question 8

Which are the most common microorganisms in nosocomial infections?

Accepted Answer

Answer reason: Escherichia coli is the most frequent cause of healthcare-associated infections, particularly catheter-associated UTIs, making it the most common nosocomial pathogen overall.

Question 9

The causative organism of enteric fever is?

Accepted Answer

Answer reason: Enteric (typhoid) fever is caused by Salmonella typhi; the other organisms cause different infections.

Question 10

Who discovered the tuberculin skin test?

Accepted Answer

Answer reason: Von Pirquet introduced the tuberculin skin (cutaneous) test in 1907; Mantoux later modified the technique. The other figures are unrelated to the TST.

Question 11

Disease that is also known as "hydrophobia"?

Accepted Answer

Answer reason: Hydrophobia refers to the painful pharyngeal spasms and fear of water characteristic of rabies, hence rabies is historically called hydrophobia.

Question 12

Man is an intermediate host of all of the following except?

Accepted Answer

Answer reason: Humans serve as intermediate hosts for malaria (mosquito is definitive), toxoplasmosis (cat definitive), and hydatid disease (dog definitive). In kala-azar (visceral leishmaniasis), humans act as the definitive/reservoir host, not the intermediate host.

Question 13

Which of the following gastroenteritis-causing microorganisms is responsible for the neonatal seizures?

Accepted Answer

Answer reason: Shigella infection in infants can produce neurotoxin effects and high fever leading to convulsions; it is classically associated with seizures among gastroenteritis pathogens.

Question 14

Widal test belongs to which of the following types?

Accepted Answer

Answer reason: The Widal test detects anti-Salmonella antibodies by visible clumping of antigen-coated particles, making it a tube agglutination test.

Question 15

Diaper rashes are most commonly caused by?

Accepted Answer

Answer reason: Among bacterial causes of diaper-area dermatitis, Staphylococcus aureus is the most common; other listed organisms are less typical.

Question 16

An infection that occurs as a result of a therapeutic or diagnostic procedure is called?

Accepted Answer

Answer reason: Iatrogenic infections result directly from medical interventions such as diagnostic or therapeutic procedures. Nosocomial refers broadly to hospital-acquired, cross infection is transmission between individuals, and opportunistic occurs in immunocompromised hosts.

Question 17

Gonorrhea is a disease transmitted through?

Accepted Answer

Answer reason: Gonorrhea is a sexually transmitted infection caused by Neisseria gonorrhoeae; transmission occurs via sexual contact, not via food, needle sticks, or blood transfusion.

Question 18

The causative organism for roundworm infestation is?

Accepted Answer

Answer reason: Human intestinal roundworm infection is caused by the nematode Ascaris lumbricoides; the other options are unrelated organisms (bacterium, louse, and a flatworm).

Question 19

Diagnosis of rabies?

Accepted Answer

Answer reason: Negri bodies are characteristic intracytoplasmic inclusion bodies in neurons seen in rabies infection and are used for diagnosis.

Question 20

What is the most common bacterial cause of acute tonsillitis?

Accepted Answer

Answer reason: Group A beta-hemolytic Streptococcus (S. pyogenes) is the most common bacterial cause of acute tonsillitis; the others are less frequent etiologies.

Question 21

Most common organism associated with cystic fibrosis?

Accepted Answer

Answer reason: In cystic fibrosis, chronic airway colonization is most commonly due to Pseudomonas aeruginosa; Burkholderia cepacia is notable but less common. Pleisomonas and Aeromonas are not typical CF pathogens.

Question 22

Which of the following is the most common cause of ophthalmia neonatorum?

Accepted Answer

Answer reason: Ophthalmia neonatorum classically results from perinatal transmission of Neisseria gonorrhoeae; among the listed organisms it is the recognized primary cause.

Question 23

Infection in a certain area consistently occurring in that population?

Accepted Answer

Answer reason: Endemic refers to a disease that is consistently present within a specific geographic area or population. Epidemic is a sudden increase above expected levels, pandemic is worldwide spread, and sporadic occurs irregularly.

Question 24

In AIDS patient, pneumonia occurs due to-?

Accepted Answer

Answer reason: AIDS patients commonly develop opportunistic pneumonia due to Pneumocystis jirovecii (formerly P. carinii), not typical bacterial pathogens like Staphylococcus, Streptococcus, or Mycoplasma.

Question 25

If a microorganism is known to produce a disease, it is referred to as a?

Accepted Answer

Answer reason: A disease-causing microorganism is termed a pathogen or pathogenic microorganism; normal flora are nonpathogenic in healthy hosts. Therefore both A and B are correct.

Question 26

Hookworm refers to the helminth?

Accepted Answer

Answer reason: Hookworm infection in humans is caused by Ancylostoma duodenale (and Necator americanus). Enterobius is pinworm, Ascaris lumbricoides is roundworm, and filaria causes lymphatic filariasis.

Question 27

Worm infestation transmitted through meat is?

Accepted Answer

Answer reason: Tapeworms (Taenia saginata/solium) are acquired by ingesting undercooked beef or pork. Hookworm, roundworm, and pinworm are not transmitted via meat.

Question 28

The stages of infection in correct sequential order are?

Accepted Answer

Answer reason: Standard sequence of infectious disease progression is incubation → prodromal → illness (acute) → convalescence.

Question 29

The antigen that forms loose and cotton wooly clumps during agglutination is.....?

Accepted Answer

Answer reason: In the Widal test, H (flagellar) antigen produces loose, fluffy cotton‑wool–like agglutination, whereas O antigen gives compact granular clumps.

Question 30

Which microorganism is most commonly responsible for Pneumonia?

Accepted Answer

Answer reason: Streptococcus pneumoniae (pneumococcus) is the most common cause of community-acquired pneumonia.

Question 31

Enteric fever is transmitted by?

Accepted Answer

Answer reason: Enteric (typhoid) fever due to Salmonella Typhi is spread via the fecal–oral route, primarily through ingestion of contaminated food or water.

Question 32

Bacteria and viruses can enter the body through?

Accepted Answer

Answer reason: Intact skin is a primary barrier to pathogens; breaks in the skin provide a direct portal of entry for bacteria and viruses.

Question 33

The Widal test is positive if the antigen titer more than?

Accepted Answer

Answer reason: A single significant Widal titer indicating active typhoid is generally ≥1:80 (especially for O agglutinins) in endemic settings.

Question 34

When the patient is acquiring infection during low immunity state is known as-?

Accepted Answer

Answer reason: Infections that occur when host defenses are weakened are termed opportunistic infections. Cross infection is spread between individuals, iatrogenic is caused by medical treatment, and nosocomial is hospital-acquired.

Question 35

Which among the following is the causative organism of tapeworm infection affecting children who consume pork?

Accepted Answer

Answer reason: Pork tapeworm infection is caused by Taenia solium; Taenia saginata is the beef tapeworm, and Echinococcus species cause hydatid disease.

Question 36

The following diseases can be transmitted by water and food except?

Accepted Answer

Answer reason: Hepatitis A, cholera, and poliomyelitis are transmitted via the fecal–oral route through contaminated food or water; Hepatitis C is primarily bloodborne and not food- or water-borne.

Question 37

An organism which takes its food from another organism without giving anything in return is called as-?

Accepted Answer

Answer reason: A parasite lives on or in another organism and derives nutrients at the host’s expense without providing benefit.

Question 38

HIV virus can be isolated from all, Except-?

Accepted Answer

Answer reason: HIV is detectable and can be isolated from blood and semen, and has been isolated from saliva, but not from skin scraping; intact skin is not a source of HIV.

Question 39

Causative organism of mumps is-?

Accepted Answer

Answer reason: Mumps is caused by the mumps virus, a paramyxovirus (historically grouped under Myxoviruses). The other options are bacteria causing unrelated diseases.

Question 40

A screen test for detection of human immunodeficiency virus (HIV) reveals a positive ELISA exam. Which of the following test will be used to confirm the diagnosis of HIV?

Accepted Answer

Answer reason: ELISA is a screening test; confirmation is done with a supplemental assay such as Western blot or indirect immunofluorescence (IFA). CD4:CD8 ratio is for monitoring, p24 antigen is a screening/early detection test, and RIPA is not the standard confirmatory test.

Question 41

Which of the following bacteria is not a source of restriction end nuclease?

Accepted Answer

Answer reason: Commonly used restriction endonucleases are sourced from Haemophilus influenzae (HindII/HindIII), Escherichia coli (EcoRI), and Bacillus amyloliquefaciens (BamHI). Agrobacterium tumefaciens is not a standard source.

Question 42

Typhoid is tested by....?

Accepted Answer

Answer reason: Typhoid can be diagnosed by Widal serology, ELISA-based antibody tests, and PCR detection of Salmonella DNA; therefore all apply.

Question 43

Acute hepatitis B infection is best diagnosed by?

Accepted Answer

Answer reason: IgM anti-HBc appears early and indicates acute or recent HBV infection, including the window period. HBsAg shows infection but not acuity, HBeAg indicates infectivity, and HBcAg is not detected in serum.

Question 44

Which disease has been eradicated from all over the world?

Accepted Answer

Answer reason: Smallpox is the only human disease certified by WHO as eradicated globally (1980). AIDS, cholera, and chickenpox still occur.

Question 45

Inoculum preparation for the fermentation medium for penicillin takes place on?

Accepted Answer

Answer reason: Penicillium inoculum for penicillin production is commonly prepared by producing spores on cereal grains such as wheat, barley, and rice; therefore, all listed substrates apply.

Question 46

In order to encounter pathogenic bacteria the relising of clutolysin should be?

Accepted Answer

Answer reason: Cytolysins/lytic factors promote destruction of bacterial cells; increasing their release enhances antibacterial action. Minimizing or stopping release would reduce microbial killing.

Question 47

In prokaryotes Ribosomes are ... in size?

Accepted Answer

Answer reason: Prokaryotes have 70S ribosomes, which are smaller than the 80S ribosomes of eukaryotes.

Question 48

A client asks you to explain viruses. Which of the following statements would be true and therefore best to include in your answer?

Accepted Answer

Answer reason: Viruses are obligate intracellular parasites; they require entry into living host cells to replicate. Other options are incorrect: normal intestinal flora are mainly bacteria, Candida is a fungus, and viruses are not the most common infectious agents across settings.

Question 49

Herpes is ................ Infection?

Accepted Answer

Answer reason: Herpes infections are caused by herpesviruses (e.g., HSV, VZV), which are viruses, not bacteria or fungi.

Question 50

Anthrax is caused by?

Accepted Answer

Answer reason: Anthrax is an infection caused by Bacillus anthracis, a gram-positive spore-forming rod. The other organisms cause different diseases (tuberculosis, cholera, botulism).

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