Microbiology Past Papers

Viral receptor HIV uses for attachment:

o CD4

o gp120

o gp41

o gp21

CD4

Markers of HBV vaccinated person:

o anti-HBsAg IgG

o anti-HBcAg IgG

o anti-HBsAg IgM

o HBsAg

the HBsAg IgG is what used in vaccine while the one with c is for past infection

How do you diagnose Lyme's disease:

o Serology

o Microscopy

o Culture

o The disease is clinically diagnosed at every stage

serology

Early localized disease (e.g., rash): Clinical diagnosis may suffice.

Later stages: Serology is required.

Which is NOT transmitted from animal to human:

rabies

poliovirus

West Nile virus

Tick borne encephalitis

poliovirus

vaccine with toxoids are not efficacious for diphtheria true or false

false

Viruses acquire their envelope during budding from the infected cell true or false

true

Schistosoma haematobium belongs to Trematoda

true

Influenza virus: segmented single stranded RNA

true

1. Each of the following statements concerning Cornybacterium diptheriae is correct except:

a. Diptheria vaccine on based on toxoid has a high incidence of adverse effects and has a very poor immunogenic effect.

b. The symptoms of diptheria can involve the respiratory tract, the heart and the peripheral nervous system.

c. Corynebacterium diptheriae is a gram-positive rod that does not form spores.

d. Toxin production is dependant on the microorganism's being lysogenised by a bacteriophage.

A

2. A chronic carrier state may occur in the following infections:

a. All others are correct

b. Hepatitis C

c. Hepatitis B

d. Hepatitis B+D

A

3. Which of the following is FALSE concerning Legionella pneumophila

a. Gram-negative rod

b. No human-human transmission

c. Aquatic saprophyte, can infect humans upon exposure to contaminated aerosols

d. Can cause congenital infections

D

4. Each of the following statements concerning visceral leishmaniasis is correct EXCEPT:

a. Can be diagnosed by detection of leishmanial DNA in bone marrow or peripheral blood

b. Occurs primarily in rural Latin America, mainly Bolivia

c. Can be caused by Leishmania donovani or Leishmania infantum

d. Is transmitted by the bite of sandflies

B

5. During which of the following phases the infection virus particle cannot be recovered within the host cell?

a. Attachment

b. Uncoating

c. Release (budding)

d. Penetration

B

Serological diagnosis

a. Can be used to detect a viral gastroenteritis (norovirus or rotavirus infection)

b. Is useful to identify viral hepatitis

c. Is useless to detect HIV infection

d. Has high sensitivity in both immunocompetent and immunocompromised individuals

B

7. One of the following statements concerning West Nile Virus is FALSE:

a. Birds are the main reservoir of infection

b. Can cause congenital infection

c. Transmitted by Culex mosquitoes

d. Neuroinvasive infection can be confirmed by IgM in the CSF

B

8. What is a common early sign of Lyme's Disease?

a. Lyme encaphalopathy

b. Erythema migrans (a lesion with flat, red border and central clearing)

c. Painless ulcer

d. Gastroenteritis

B

9. Each of the following statements concerning Strongyloides stercoralis is correct EXCEPT

a. Larvae of S. stercoralis can be found in the soil

b. S. stercoralis can cause disseminated infection in the immunocompromised host

c. Migrating larvae of S. Stercoralis induce eosinophilia

d. S. stercoralis infection is acquired by ingestion of contaminated water

D

10. In order for HIV to attach, the host cell must have

a. A CD8 receptor and a cell specific co-receptor (such as CCR5)

b. A CD4 receptor and a nonspecific receptor

c. A CD4 antigen receptor and a cell specific co-receptor (such as CCR5)

d. A gp120 receptor

C

11. Which of the following sentences concerning prevention of viral hepatitis is FALSE?

a. Hepatitis B infection may be prevented by vaccination

b. Hepatitis A infection may be prevented by vaccination

c. Hepatitis Delta infection may be prevented by vaccination against HBV

d. Hepatitis E infection may be prevented by vaccination

D

12. One of the following statements concerning Mycoplasma is FALSE?

a. The smallest free-living bacteria

b. Exists in the forms of elementary bodies and reticular bodies

c. Can cause infections in the urogenital tract

d. Lack peptidoglycan in the cell wall

B

13. Each of the following statements concerning Staphylococcus aureus is TRUE except:

a. Endotoxin is an important pathogenic factor

b. 15-50% of healthy individuals are carriers of this microorganism

c. Grow in high concentration of salts

d. Gram-positive cocci in grapelike clusters are seen on Gram-stained smear

A

14. Animal diseases that can be transmitted to humans are termed

a. Panzootic

b. Enzootic

c. Epizootic

d. Zoonoses

D

15. Which are the primary stain and counter stain used in Ziel Neelsen stain (acid fast stain)

a. Crystal violet and safranin

b. Crystal violet and iodine

c. Carbolfuchsin and hypochlorite

d. Carbolfuchsin and methylene blue

D

16. Regarding the Gram stain, which one of the following is the MOST accurate?

a. After adding crystal violet and Gram's iodine, both gram-positive bacteria and gram-negative bacteria will appear blue.

b. If you forget to heat-fix both gram-positive and gram-negative bacteria will appear blue.

c. If you forget to stain with the red dye (safranin), both gram-positive and gram-negative bacteria will appear blue.

d. One reason why bacteria have a different colour in this stain is because the gram-positive bacteria have lipid in their membrane, whereas gram-negative bacteria do not.

A

17. Each of the following statements concerning malaria is correct EXCEPT

a. The female Anopheles mosquito is the vector.

b. Early in infection, sporozoites enter hepatocytes

c. The principal site of gametocyte formation is the human gastrointestinal tract

d. Release of merozoites from red blood cells causes periodic fever and chills.

C

18. The neuraminidase of influenza virus exhibit the following properties EXCEPT:

a. Is embedded in the outer surface of the viral envelope.

b. Binds to the sialic acid receptor present in the upper respiratory tract.

c. Facilitates release of virus particles from infected cells.

d. Lowers the viscosity of the mucous film in the respiratory tract.

B

19. The term human microbiota refers to which of the following?

a. All non-pathogenic microorganisms in a certain geographic region.

b. All non-pathogenic microorganisms in the human body.

c. All microorganisms involved in parasitism in humans.

d. All microorganisms of the same species infecting humans.

B

20. Trachoma is

a. An urological infection

b. A chronic keratoconjunctivitis

c. A chronic infection caused by Treponema pallidum

d. A chronic pneumonia

B

21. Each of the following statements concerning Schistoma haematobium is correct EXCEPT:

a. Snails are intermediate hosts of S. haematobium

b. S. haematobium belongs to nematoda

c. S. haematobium is acquired by humans when cercariae penetrate the skin

d. Diagnosis of schistomiasis can be performed by the detection of eggs in urine by microscopy

B

22. Which of the following components is present in the plasma membrane of fungal cells, but not in mammalian cells?

a. Ergosterol

b. Chitin

c. Cholesterol

d. Lipopolysaccharides

A

23. One of the following statements concerning Chlamydia is FALSE:

a. Lack peptidoglycan in the cell wall.

b. Exist in the forms of elementary bodies and reticular bodies

c. The biggest bacteria

d. Obligate endocellular parasites

C

24. A 4-year old boy presents to his paediatrician with intense perineal itching. Eqqs with flattened sides were identified by microscopic examination of a perineal tape test. Infection with which of the following is most likely?

a. Schistoma mansoni

b. Enterobius vermiculus

c. Strongyloides sterocalis

d. Ascaris lumbricoides

B

25. Which one of the following is a virulence factor for Staphylococcus aureus?

a. All other answers are correct

b. MSCRAMM proteins (adhesins)

c. Exfoliative toxin A

d. Protein A that binds to the Fc portion of IgG inhibiting phagocytosis.

A

26. Each of the following statements concerning Chagas disease (caused by Trypanosoma cruzi) is correct EXCEPT:

a. Chagas disease can be diagnosed by serology (detection of specific IgG)

b. Chagas disease is caused by hemoflagellate protozoa

c. The infection is transmitted by triatomine bugs

d. Chagas disease is of concern only in Latin America

D

27. The following methods may be used for serological diagnosis EXCEPT:

a. Indirect immunofluorescence test

b. ELISA

c. Polymerase chain reaction

d. Western blot

C

28. The hepatitis D virus has a special dependence upon which hepatitis virus?

a. C

b. B

c. A

d. E

B

29. Which one of the following statements concerning immunization against diseases caused by clostridia is correct?

a. Antitoxin against tetanus protects against botulism as well because the two toxins share antigenic site

b. Antitoxin against tetanus is effective in protecting against gas gangrene

c. Immunization with tetanus toxoid induces effective protection against tetanus toxin

d. The toxoid vaccine against Clostridium difficile infection should be administered to immunocompromised patients

C

30. Which of the following is false concerning viruses?

a. May contain enzymes for replication

b. Have their own metabolism

c. May contain RNA only

d. May have an envelope

B

31. What are mechanisms of asexual reproduction of molds?

a. Molds exhibit only sexual reproduction

b. By blastoconidia or by thalloconidia

c. By binary fission

d. By budding

B

32. Each of the following statements concerning the mechanism of action of antibacterial drugs is correct EXCEPT

a. Macrolides disrupt cell membranes by a detergent-like action

b. Tetracyclines inhibit protein synthesis by blocking tRNA binding

c. Cephalosporins inhibit the transpeptidase reaction and inhibit cell wall synthesis

d. Aminoglycosides inhibit protein synthesis by misreading of codon by tRNA

A

33. One of the following sentences concerning enveloped viruses is FALSE

a. Enveloped viruses do not survive in the gastrointestinal tract

b. Enveloped viruses are released by budding

c. Enveloped viruses need to kill the host cell to spread

d. Enveloped viruses are disrupted by acids, detergents and drying

C

34. In Kirby-Bauer test

a. None of the other answers describe the Kirby-Bauer test

b. Maldi-TOF technique is employed to measure bacterial reproduction

c. The bacterial strain to be tested is placed on a plate of agar medium and discs of antibiotics are added to the plate. After allowing the bacteria to grow overnight, areas of clear media surrounding the discs indicate that the antibiotic inhibits bacterial growth. Clear areas can be measured and results compared to reference standard/

d. 90-well plates are filled with a broth composed of the bacterial strain to be tested and varying concentration of the antibiotics. After incubation time, the plate is removed and checked for bacterial growth. If the broth became cloudy or a layer of cells formed at the bottom, then bacterial growth has occurred, indicating resistance of the bacteria to a specific antibiotic

C

35. One of the following concerning Ebola virus is TRUE

a. Belongs to the Filoviridae family

b. Birds are the main reservoir of infection

c. Can be transmitted by mosquitoes

d. Serology is the gold standard for diagnosis

A

36. Gram +ve. Cell walls:

a. Has a thin layer of peptidoglycans

b. Is impermeable to ions

c. Contains teichoic acids that are highly antigenic

d. Has glycine bridges linking lateral amino acid chains

C

37. Bordetella pertussis

a. Is a gram-positive bacterium

b. Has no vaccine

c. Its prevalence in Europe is decreasing

d. Is a coccobacillus

D

38. What are the gold standard(s) for fungi?

a. Culture

b. Culture and serology

c. Serology

d. Clinical diagnosis

A

39. Active TB:

a. Is always contagious

b. They do not disseminate in the blood

c. Contagious after bronchial airways and after reached airways

d. None of the above

C

40. Bordella pertussis diagnosis is carried out with:

a. We prefer to use microscopy with gram staining

b. We use aspecific culture

c. We prefer nucleic acid amplification assays

d. Serological diagnosis

C

41. H. Influenza can be diagnosed with:

a. Serotyping as first resource for diagnosis

b. Nucleic acid amplification test for respiratory secretions

c. Culture with blood agar

d. Culture with chocolate agar

D

42. In which form do Plasmodia enter our blood?

a. Merozoites

b. Hypnozoites

c. Sporozoites

d. Schizonts

C

43. We can find the amastigote form of Leishmania spp.

a. In the host intracellularly

b. In the Vector intracellularly

c. In the host extracellularly

d. In the vector extracellularly

A

44. Diagnosis of acute Chagas disease

a. Serology

b. ELISA test

c. PCR

d. All of the above

C

45. Leptospira interrogans

a. Have both ends coiled like a hook

b. Don't stay easily in the environment

c. Enter through mucous membranes except conjunctiva

d. Infect through fresh water

D

46. Disease given by L. interrogans

a. Is monophasic

b. Can give hepatic and renal dysfunction

c. Is widely diffused in Europe

d. All of the above

B

47. About mycoplamataecae, which is false?

a. Are smallest free-living bacteria

b. Cause respiratory tract a urogenital disease

c. Are very plastic because of a lack of a cell wall

d. Cephalosporins are used for treatment

D

48. About Rickettsiaceae, which is false?

a. Small, intracellular bacteria

b. Reside within the phagosome during intracellular life cycle

c. Stain weakly with Gram staining

d. Enter host cell by stimulating own phagocytosis

B

49. Which of the following is a TRUE statement regarding quinolones?

a. Work only against gram-positive bacterial infections

b. Act on topoisomerase I & III

c. Inhibit nucleic acid replication and transcription

d. Are not used anymore because they threaten human cells.

C

50. Cytomegalovirus

a. Is not transmissible through sexual contact

b. The primary infection is often symptomatic

c. It is an oncogenic virus

d. Can cause congenital infection

D

51. Clinical signs of infection of Staphylococcus aureus:

a. Enterotoxins can cause food poisoning

b. In Bullous impetigo of vesicles release bacteria

c. Toxic shock syndrome is common but with low mortality

d. Staphylococcal scalded skin syndrome occurs in the elderly

A

52. Schistosomas penetrate human skin in the form of

a. Miracidia

b. Schistosomulum

c. Cercariae

d. Sporocysts

C

53. Genitourinary schistosomiasis is caused by

a. S. mansoni

b. S. haematobium

c. S. japonicum

d. S. intercalatum

B

54. Aspergillus fumigatus can be involved in a variety of clinical conditions. Which one of the following is LEAST LIKELY to occur?

a. Allergic bronchopulmonary aspergillosis

b. Colonisation of pre-existing cavities in the lung

c. Thrush

d. Lung invasion in immunocompromised host

C

55. Fish are the source of human infection by one of the following parasites

a. Echinococcus granulosus

b. Ascaris lumbricoides

c. Anisakis spp.

d. Taenia saginata

C

Which medium you DO NOT use when culturing VIRUSES?

Cells

Fetal Cells

Animal Blood

ANIMAL BLOOD - liquid mediums can't be used to culture viruses, all other are ok)

What is present in case of vaccination against HBV

HBcIgG

HBcIgM

HBsIgG

HBsAg

D

What do you use as a way of diagnosis for Stronglyocide in immunocompetent individuals

Antigen in serum

Anti-steroglydes IgG

Antigen in stool

Microscopy in stool

Anti-steroglydes IgG (most sensitive)

What is the infective stage of Giardia Intestinalis

Eggs

Sporozoites

Cysts

cyst

Which of the following sentences concerning cysticercosis is TRUE?

a. Diagnosis is performed by detection of proglottids or eggs by microscopy in stool

b. Transmitted to humans by ingestion of undercooked pork meat

c. symptoms are usually mild; it causes abdominal distention, sometimes weight loss

d. It occurs when humans act as intermediate hosts for Taenia solium infection

D

Bacterial endospores:

a. Serve for bacterial adherence to the host mucosal membranes

b. Can be produced by some Gram positive bacteria in adverse enviromental condition

c. Possess a reproductive function

d. Possess an enhanced metabolic activity

b

In Kirby-Bauer test:

a. Maldi-TOF technique is employed to measure bacterial reproduction

b. The bacterial strain to be tested is placed on a plate of agar medium and disks of antibiotics are added to the plate. After allowing the bacteria to grow overnight, areas of clear media surrounding the disks indicate that the antibiotic inhibits bacterial growth. Clear areas can be measured and results compared to reference standard

c. none of the other answers describe the Kirbi-Bauer test

d. 96-well plates are filled with a broth composed of the bacterial strain to be tested and varying concentrations of the antibiotics. After incubation time, the plate is removed and checked for bacterial growth. If the broth became cloudy or a layer of cells formed at the bottom, then bacterial growth has occurred, indicating resistance of the bacteria to a specific antibiotic

b

The following methods may be used for serological diagnosis:

a. Culture

b. Indirect immunofluorecence test

c. Immunochromatographic test

d. ELISA

a

The two most common types of viral vaccines are inactivated vaccines and live, attenuated vaccines. Regarding these vaccines, which one of the following statements is TRUE? :

a. inactivated vaccines induce a longer-lasting response than do live, attenuated vaccines

b. inactivated vaccines induce a broader range of immune responses than do live, attenuated vaccines

c. inactivated vaccines are no longer used

d. inactivated vaccines are safer to give to immunocompromised patients than are live, attenuated vaccines

D

Which of the following terms refers to a prokaryotic cell that is comma shaped?

a. spirillum

b. coccus

c. vibrio

d. coccobacillus

c

The cell wall of Gram positive bacteria is

a. none of the other 3 answers is correct

b. can be produced by all types of bacteria in adverse enviromental condition

c. thinner than in Gram negative bacteria

d. thicker than in Gram negative bacteria

D

One of the following statements concerning antiviral drugs is FALSE

a. Molnupiravir is a nucleoside analog that targets the SARS-CoV2 RNA-dependent-RNA polymerase

b. Most antiviral drugs target the viral genome replication or transcription

c. Zanamivir (Relenza) and oseltamivir (Tamiflu) act against influenza virus; they are neuraminidase inhibitors and prevent new viral particles from being released

d. The activity of most antiviral drugs virus is extended to viruses belonging to different families

D

Which of the following antibiotics act by inhibiting the bacterial protein synthesis? :

a. Aminoglycosides

b. Tetracyclines

c. All other answers are correct

d. Macrolides

C

The main host defense/s against bacterial exotoxins is/are :

a. Modulation of host cell receptors in response to the toxin

b. Activated macrophages secreting proteases

c. Specific neutralizing antibodies

d. Helper T cells

C

Which of the following statement is FALSE? :

a. Treatment of HIV infection requires a combined therapy

b. Integrase inhibitors are active against HSV type I and II

c. Protease inhibitors are active against HIV

d. Neuroaminidase inhibitors are active against influenza virus

B

Diarrhea associated with prolonged antibiotic treatment, including pseudomembranous colitis, is MOST FREQUENTLY caused by :

a. Shigella dysenteriae

b. Salmonella enteritidis

c. Yersinia enterocolitica

d. Clostridium difficile

D

How is active TB disease diagnosed? :

a. Direct methods, including microscopy, culture and PCR

b. Mantoux test (also called PPD test)

c. Serology

d. IGRA (also called Quantiferon TB)

A

The diagnosis of Streptococcus pyogenes pharyngitis :

a. is a clinical diagnosis

b. requires culture on blood agar plate from throat swab specimen

c. none of the other three statements is correct

d. can be perfomed by serology (detection of specific IgM and IgG)

B

One of the following statements regarding infections caused by Rickettsiaceae is FALSE

a. Rickettsial infection are often zoonosis

b. Rickettsiae are obligate intracellular rods

c. Rickettsial infections are vector-borne

d. Rickettsiaceae often cause chronic hepatitis

D

The term human microbiota refers to which of the following?

a. all non pathogenic microorganisms in the human body

b. all microorganisms involved in parasitism in humans

c. all microorganisms of the same species infecting humans

d. all non-pathogenic microorganisms in a certain geographic region

A

What is the most common early sign of Lyme disease? :

a. Gastroenteritis

b. Painless ulcer

c. Lyme encephalopathy

d. Erythema migrans (a lesion with flat, red border and central clearing)

D

Which one of the following is a virulence factor for Staphylococcus aureus? :

a. all the other answers are correct

b. MSCRAMM proteins (adhesins)

c. protein A that binds to the Fc portion of IgG inhibiting phagocytosis

d. exfoliative toxin A

A

One of the following statements concerning Streptococcus pneumoniae is TRUE :

a. Disease caused by S.pneumoniae is most common in the elderly and young children

b. Colonies appear beta-hemolytic on blood agar plates

c. Gram negative diplococci

d. All the other three answers are correct

A

One of the following statements concerning Rotavirus infection is TRUE :

a. No vaccination is available

b. The infection is a zoonosis

c. The virus is mainly transmitted by the respiratory route

d. Major cause of diarrhea in small children

D

The following viruses are transmitted from animals to humans EXCEPT :

a. Tick borne encephalitis virus

b. Papillomavirus

c. Rabies Virus

d. West Nile virus

B

Viruses that routinely establish latent infections in human sensory ganglia include :

a. Herpes Simplex Virus type 1 and 2 and Varicella-Zoster Virus

b. Epstein-Barr virus

c. All viruses belonging to the Herpesviridae family

d. Varicella-Zoster Virus only

A

One of the following statements concerning Rhinovirus infection is TRUE

a. Only one serotype of Rhinovirus exists

b. Rhinoviruses are non-enveloped, small, RNA viruses

c. The infection will cause the development of permanent immunity

d. The virion is very resistant and the transmission occurs via fecal-oral route

B

A chronic infection may occur in the following: :

a. hepatitis A

b. hepatitis C

c. all the 3 other answers are correct

d. hepatitis E

B

Which of the following marker/s is/are present in the serum during chronic hepatitis C infection?

a. anti-HCV IgG and HCV RNA

b. HBsAg and anti-HBc IgM

c. anti-HCV IgG only

d. anti-HCV IgM and IgG

A

The hepatitis D virus has a special dependence upon which hepatitis virus? :

a. C

b. B

c. E

d. A

B

One of the following statements concerning rabies virus and rabies infection is FALSE

a. if a patient is bitten by a dog, the rabies vaccine should be given together with rabies immunoglobulins in countries where rabies is endemic

b. once the individual is infected through an animal bite, the rabies virus reaches the central nervous system within 2 or 3 days

c. rabies virus is transmitted through the bite of a rabid animal (most often a dog)

d. the rabies virus always causes a letal encephalitis once it reaches the central nervous system

B

Infection with HIV will result in a depletion of

a. B cells

b. CD4+ T cells

c. Neutrophils

d. Red blood cells

B

The genome in influenza viruses is :

a. Double stranded DNA

b. Double stranded RNA

c. Segmented, single stranded RNA

d. Circular, single stranded RNA

C

The definitive host for the causative agent of toxoplasmosis is the

a. there is no definitive host in Toxoplasma infection, as the parasite is monoxenous

b. dog

c. human

d. cat

D

Each of the following statements concerning Trematoda (flukes) is correct EXCEPT

a. often hermaphrodites (except Schistosoma spp.)

b. the proglottids contain the reproductive system and eggs

c. heteroxenous parasites, the intermediate hosts are snails

d. Flattened oval or worm-like shape

B

Each of the following statements concerning hookworm infection (Ancylostoma duodenale/Necator americanus) is correct EXCEPT

a. Hookworm infection is a soil-transmitted helminthiasis

b. Hookworm infection can cause anemia

c. Hookworm infection can be diagnosed by finding the trophozoites in the stool

d. Hookworm infection is acquired by humans when filariform larvae penetrate the skin

C

Protozoa can move through:

a. Pseudopodes

b. Flagella

c. All the other answers are correct

d. Cilia

C