Pharma Microbiologist Interview Questions & Answers

Question 1. Describe The Colour (in A Gram Stained Smear) Of Gram Positive And Gram Negative Bacteria, Respectively?

Answer :

• Gram positives: dark blue/purple
• Gram negatives: red/pink

Question 2. Describe The 3 Important Parts Of The Bacterial Lipopolysaccharide?

Answer :

Lipid A + core polysaccharide + O-specific (polysaccharide) side chain

Question 3. List The Possible Shapes Of Bacteria. Write One Example For Each Category?

Answer :

• Coccus (spherical): Staphylococcus, Streptococcus
• Rod: Clostridium, Corynebacterium, Gram negative rods
• Curved rod: Vibrio
• Helical: Spirochetes (Treponema, Borrelia, Leptospira)

Question 4. What Are The Essential Components Of Bacterial Cells? Specify At Least 3?

Answer :

Cytoplasm, nucleoid (genome), cell membrane, (cell wall)

Question 5. Which Part Of The Bacterial Cell Carries The Endotoxin?

Answer :

Outer membrane of Gram negative bacteria

Question 6. What Role Is Attributed To The Bacterial Capsule In The Infectious Process?

Answer :

Antiphagocytic effect, adhesion

Question 7. Describe The Definition For Obligate Anaerobic Bacteria?

Answer :

They are able to replicate only in the absence of oxygen (under anaerobic conditions).

Some of them are quickly killed by oxygen, some are able to survive but do not grow while oxygen is present.

Question 8. Describe The Definition For Facultative Anaerobic Bacteria?

Answer :

They are able to replicate both in the presence and in the absence of oxygen. In aerobic conditions, they perform respiration, in anaerobic condition, they perform fermentation.

Question 9. What Does Sterilisation Mean?

Answer :

Sterilisation means the killing or removal of all microorganisms (including bacterial spores).

Question 10. Mention 3 Reliable Methods Of Sterilization?

Answer :

• Autoclaving, hot air oven, gamma-radiation, filtration (fluids), gas sterilization (not acceptable: boiling, pasteurization, UV!)
• Specify an exact set of parameters (temperature and time) necessary for effective sterilization by autoclaving!
• 121 °C for 20 min. (at 1 bar overpressure)
• Specify an exact set of parameters (temperature and time) necessary for effective sterilization using a hot air oven (with circulation)!
• 160 °C for 60 min. (dry heat)

Question 11. What Does Disinfection Mean?

Answer :

The purpose of disinfection is the killing of pathogenic microbes. Resistant microbes and spores may survive, so disinfection does not the kill all microbes.

Question 12. Mention 5 Groups Of Disinfectants?

Answer :

Alcohols, phenol derivatives, detergents, chlorine, iodine, aldehydes

Question 13. Mention 2 Groups Of Disinfectants Acting On The Microbial Membrane Structures?

Answer :

• (cationic) detergents (quaternary ammonium compounds)
• phenol compounds (cresol, hexachlorophene, chlorhexidine)
• alcohols (ethanol, isopropanol)

Question 14. What Does Active Immunization Mean?

Answer :

It means the transfer of microbes or microbial products (vaccines) to the human body to induce long-lasting immunity against a specific infectious disease

Question 15. What Does Passive Immunization Mean?

Answer :

It means the administration of preformed antibody (immune globulins produced in animals or humans) to the human body resulting in short-term protection against a specific infectious disease.

Question 16. What Is The Nature Of Antigen In The Vaccines Used To Prevent Infections By Streptococcus Pneumoniae, Haemophilus Influenzae And Neisseria Meningitidis?

Answer :

Capsular polysaccharide (either alone or conjugated to a carrier protein)

Question 17. What Does The Vaccine Against Tuberculosis (bcg) Contain?

Answer :

Live attenuated Mycobacterium bovis (Bacille Calmette-Guerin)

Question 18. What Does The Vaccine Against Pertussis Contain?

Answer :

Previously: killed bacteria

Currently: acellular vaccine (toxoid + other purified proteins)

Question 19. What Do The Vaccine(s) Against Diphtheria And Tetanus Contain?

Answer :

Diphtheria and tetanus toxoid

Question 20. Specify The 4 Groups Of Bacterial Vaccines According To The Nature Of The Antigen?

Answer :

• live, attenuated vaccines
• killed bacterial vaccines
• toxoid vaccines
• subunit vaccines (capsular polysaccharide or purified protein)

Question 21. What Are The Main Advantages And Disadvantages Of Live Attenuated Vaccines As Compared To Killed Vaccines?

Answer :

Advantages: induce not only serum antibodies but also cellular immunity and local IgA antibodies. Some may be applied orally. Usually fewer doses are needed.

Disadvantages: Attenuated strains may revert to virulent in rare cases. They may cause disease in immunosuppressed patients. Live attenuated microbes are usually heat sensitive and must be refrigerated.

Question 22. Mention 2 Bacterial Exotoxins That Act By Adp Ribosylation?

Answer :

Diphtheria toxin, cholera toxin, pertussis toxin

Question 23. Mention 2 Bacterial Exotoxins That Are Neurotoxic?

Answer :

Tetanus toxin, botulinum toxin

Question 24. What Is The Mechanism Of Action Of Diphtheria Toxin?

Answer :

Inhibition of protein synthesis in eukaryotic cells by ADP-ribosylation of ribosomal EF-2 (elongation factor-2)

Question 25. What Is The Mechanism Of Action Of Tetanus Toxin?

Answer :

It causes spastic paralysis by blocking the release of inhibitory neurotransmitters (glycine and GABA) in synapses

Question 26. Mention At Least Three Of The Physiological Effects Of Septic Shock (characterized By The Presence Of Large Amount Of Bacterial Endotoxin In The Blood)?

Answer :

Fever, hypotension, disseminated intravascular coagulation (DIC), complement activation, impaired organ perfusion, hypoglycaemia

Question 27. Mention 2 Non-essential Bacterial Organelles That Enhance Bacterial Virulence! Describe How Their Function Contributes To Pathogenicity?

Answer :

• Capsule: antiphagocytic effect, adhesion to tissues
• Fimbriae: binding to tissues
• Flagellae: spreading the bacteria

Question 28. Mention 4 Extracellular Enzymes Of Bacterial Origin Functioning As Virulence Factors?

Answer :

Coagulase, streptokinase (fibrinolysis), streptodornase (DNase), hyaluronidase, IgA protease, collagenase, elastase, urease.

Question 29. What Is A Vector? Write An Example?

Answer :

Vector is an arthropod that transmits infection from human to human, or from animal to human.

Examples. Tick – Lyme disease; louse – epidemic typhus; mosquito – malaria

Question 30. Mention 2 Infectious Diseases That Are Transmitted To Humans By Tick Bites?

Answer :

Tick-borne encephalitis; Lyme-disease; tularemia; Rocky-Mountain spotted fever; etc.

Question 31. What Is A Reservoir? Write An Example?

Answer :

The normal host of a pathogen (human or animal) serving as a continuous source of infection to other hosts (such as humans). Salmonella typhi – human; Yersinia pestis - rodents.

Question 32. Mention At Least 5 Possible Transmission Ways Of Infections? Respiratory Droplets (infectious Aerosol)?

Answer :

• Faecal-oral
• Direct contact (such as sexual)
• Fomites (inanimate objects)
• Blood
• Vectors (blood-sucking arthropods)

Question 33. What Is The Difference Between Prevalence And Incidence Of An Infectious Disease?

Answer :

It can be differentiated in chronic diseases. Prevalence: total number of diseases (per 100,000 people). Incidence: number of new cases in a year (per 100,000 people).

Question 34. Why Is Multi-drug Therapy Used For Tuberculosis?

Answer :

To prevent the overgrowth of drug-resistant mutants during the long treatment period (if bacteria resistant to one drug emerge, they are most probably inhibited by the other drugs).

Question 35. What Is The Main Immune Defense Mechanism Against Mycobacterium Tuberculosis?

Answer :

Activated macrophages

Question 36. What Disease Is Caused By Mycobacterium Avium-intracellulare? What Patients Are Characteristically Susceptible To Infection?

Answer :

It causes TB, especially in immunosuppressed patients (such as AIDS patients).

Question 37. Mention One Aerobic And One Anaerobic Bacterium Of The Normal Flora Of The Skin?

Answer :

Aerobic: Staphylococcus epidermidis

Anaerobic: Propionibacterium acnes

Question 38. Give Two Genuses For Each Category Of Bacteria?

Answer :

Gram positive aerobic: Staphylococcus, Streptococcus, Bacillus, Corynebacterium

Gram positive anaerobic: Clostridium, Actinomyces, Propionibacterium, Lactobacillus

Question 39. Which 3 Bacterial Species Are The Most Important Causative Agents Of Meningitis Among Babies (> 1 Month Of Age) And Children?

Answer :

Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae

Question 40. What Are The Main Symptoms In The Different Stages Of Syphilis?

Answer :

Primary syphilis: nontender ulcer (hard chancre)

Secondary lesions: maculopapular rash on skin, and condylomata lata on mucous membranes

Tertiary stage: granulomas (gummas), central nervous system involvement (tabes dorsalis, paralysis progressiva), cardiovascular lesions (aortitis, aortic aneurysm)

Question 41. Which Are The Two Different Kinds Of Antibodies Used In The Diagnosis Of Syphilis? Give Examples For Tests Demonstrating Them?

Answer :

Reagin (nonspecific antibody) – RPR, VDRL (flocculation tests)

Immobilising (specific antibody) – TPHA (T. pallidum hemagglutination),

FTA-ABS (fluorescent treponemal assay – with antibody absorption), TPI (T. pallidum immobilisation test)

Question 42. What Is The Advantage And Disadvantage Of The Fta-abs Syphilis Serologic Test Compared To The Vdrl Test?

Answer :

Specific (treponemal) tests such as FTA-ABS are more specific, but they cannot be used to follow the efficacy of treatment (because the specific antibodies persist even after effective eradication of bacteria)

Question 43. Which Manifestations Are Characteristic For The Late Phases Of Lyme Disease?

Answer :

Arthritis, cardiac manifestations (myocarditis, pericarditis) and neurological involvement (meningitis, peripheral neuropathies)

Question 44. Mention 4 Bacteria Causing Atypical Pneumonia?

Answer :

• Chlamydia pneumoniae
• Chlamydia psittaci
• Coxiella burnetii
• Mycoplasma pneumoniae
• Legionella pneumophila

Question 45. Which Two Diseases Are Caused By Rickettsia Prowazekii?

Answer :

Louse-borne epidemic typhus

Recurrent form: Brill-Zinsser disease

Question 46. What Is The Causative Agent Of Epidemic Typhus?

Answer :

Rickettsia prowazekii

Question 47. What Is The Causative Agent Of Endemic Typhus?

Answer :

Rickettsia typhi

Question 48. How Can Be Chlamydiae And Rickettsiae Cultivated?

Answer :

These are obligate intracellular bacteria, can be cultured in experimental animals, embryonated eggs, and cell culture

Question 49. List The Serotypes Of Chlamydia Trachomatis And The Diseases Caused By Them?

Answer :

Types A, B and C: trachoma (chronic conjunctivitis)

Types D-K: genital tract infections (NGU, PID), inclusion conjunctivitis

Types L1-L3: lymphogranuloma venereum (STD)

Question 50. Why Are Penicillins Not Effective Against Mycoplasma Pneumoniae Infections?

Answer :

Because of the absence of a cell wall, penicillins are ineffective (penicillins inhibit cell wall synthesis)

Question 51. Mention 4 Bacteria Frequently Causing Sexually Transmitted Diseases (std)?

Answer :

Treponema pallidum, Neisseria gonorrhoeae, Haemophilus ducreyi, Chlamydia trachomatis, (Calymmatobacterium granulomatis)

Question 52. What Does Fungal Dimorphism Mean?

Answer :

The same species is capable of existing in two morphological forms (yeast or mold), depending on enviromental conditions (temperature, nutrients)

Question 53. Which Are The 4 Fungal Species Causing Systemic Mycosis?

Answer :

Coccidioides immitis, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidioides brasiliensis

Question 54. Mention 3 Species Causing Opportunistic Fungal Infections?

Answer :

Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Mucor spp., Rhizopus spp.

Question 55. What Are The Different Forms Of Pulmonary Aspergillosis?

Answer :

Aspergillus ball (in preformed cavities)

Invasive aspergillosis (in immunosuppression)

Allergic bronchopulmonary aspergillosis

Question 56. What Is The Usual Site Of Entry Of Fungi Causing Systemic Mycoses?

Answer :

Respiratory tract(Inhalation)

Question 57. Which Human Pathogenic Fungus Has A Capsule?

Answer :

Cryptococcus neoformans

Question 58. What Are The 3 Modes Of Transmission For Human Toxoplasma Gondii Infection?

Answer :

• Eating undercooked meat containing tissue cysts,
• Contact with cat feces containing oocysts
• Transplacental transmission

Question 59. Which 2 Protozoa May Infect The Human Foetus Transplacentally?

Answer :

• Toxoplasma gondii
• Plasmodium species

Question 60. Which Species Are The Causative Agents Of Malaria?

Answer :

Plasmodium vivax, P. ovale, P. malariae, P. falciparum

Question 61. What Is The Laboratory Diagnosis Of Malaria?

Answer :

Giemsa-stained blood smears. Thick smear is used to screen for the agent, thin smear is used to identify the species.

Question 62. How Can One Diagnose Amebic Dysentery?

Answer :

Microscopic demonstration of E. histolytica cysts and trophozoites from feces

Question 63. How Can One Diagnose Trichomonas Vaginalis Infection?

Answer :

Direct demonstration of protozoa in wet mount or stained smear of clinical specimens (vaginal, urethral or prostatic secretions).

Question 64. How Can One Diagnose Intestinal Taeniasis?

Answer :

Demonstration of characteristic proglottids and eggs (ova) in faeces.

Question 65. Mention 2 Worm Species That Migrate Through The Human Lungs In The Larval Stage?

Answer :

• Ascaris lumbricoides
• Ancylostoma duodenale
• Necator americanus
• Strongyloides stercoralis

Question 66. How Can One Diagnose Enterobius Infection?

Answer :

Demonstration of eggs (ova) recovered from perianal skin (Scotch tape technique). Not from feces!

Question 67. Mention 4 Tissue Infecting Filarial Nematodes?

Answer :

• Wuchereria bancrofti
• Loa loa
• Onchocerca volvulus
• Dracunculus medinensis

Question 68. How Is Human Fasciola Hepatica Infection Acquired?

Answer :

By eating aquatic vegetation containing encysted larvae (Rarely: by eating raw sheep liver containing adult worms)

Question 69. What Disease Is Caused If Humans Are Infected Per Os With Taenia Solium Eggs?

Answer :

Human cysticercosis (encysted larvae in brain, eyes, etc.)

Question 70. Mention 2 Helminths Whose Larvae Enter The Human Body By Penetrating The Intact Skin?

Answer :

• Schistosoma
• Ancylostoma duodenale
• Necator americanus
• Strongyloides stercoralis

Question 71. What Are The Definitive, And The Intermediate Hosts Of Taenia Saginata, Respectively?

Answer :

Definitive host: human

Intermediate host: cattle

Question 72. What Are The Definitive, And The Intermediate Hosts Of Taenia Solium, Respectively?

Answer :

Definitive host: human

Intermediate host: swine (pig)

Question 73. What Is The Infectious Form Of Strongyloides Stercoralis?

Answer :

Filariform larva

Question 74. What Is The Infectious Form Of Trichuris Trichiura?

Answer :

Embryonated egg

Question 75. Is Autoreinfection Possible In Ascaris Lumbricoides Infection? If Yes, When?

Answer :

No, the eggs must mature in the soil for several days to become infectious (embryonated)

Question 76. Is Autoreinfection Possible In Strongyloide Stercoralis Infection? If Yes, When?

Answer :

Yes, especially in immunosuppression (for example: AIDS)

Question 77. Is Autoreinfection Possible In Enterobius Vermicularis Infection? If Yes, When?

Answer :

Yes, the eggs become infectious in a few hours, and ab ano ad os autoinfection may occur (especially in children)

Question 78. Mention 3 Dna Virus Families Containing No Envelope?

Answer :

Parvoviridae, Papillomaviridae, Adenoviridae

Question 79. Mention 3 Dna Virus Families Containing Envelope?

Answer :

Herpesviridae, Hepadnaviridae, Poxviridae

Question 80. Mention 3 Rna Virus Families Containing No Envelope?

Answer :

Picornaviridae, Caliciviridae, Reoviridae

Question 81. Mention 3 Rna Virus Families Containing Envelope?

Answer :

Orthomyxoviridae, Paramyxoviridae, Rhabdoviridae, etc.

Question 82. Which Virus Family Is Characterized By A Double-stranded Rna Genome?

Answer :

Reoviridae

Question 83. Reverse Transcription Is Involved In The Replication Of Which Dna Virus?

Answer :

Hepadnaviridae – HBV

Question 84. What Are The Serious Complications Of Hsv Infection In Newborns?

Answer :

Disseminated infections, encephalitis, skin, eye, mouth infections

Question 85. Which Viruses Are Susceptible To Acyclovir? What Is The Mechanism Of Effect Of The Drug?

Answer :

Alpha herpesviruses – HSV1, HSV2, VZV; inhibitor of viral DNA polymerase and DNA chain terminator

Question 86. Explain Why Acyclovir Is Selectively Toxic To Cells Infected By Alpha-herpesviruses?

Answer :

These viruses encode their own thymidine kinase enzymes, which are needed for activation (phosphorylation) of the drug. Cellular thymidine kinase does not activate the drug.

Question 87. In Which Cells Do Herpes Simplex Viruses Establish Latent Infection?

Answer :

Sensory ganglion cells (trigeminal or sacral ganglia)

Question 88. What Is The Possible, Late Complication (years After Acute Infection) Of The Childhood Chickenpox?

Answer :

Herpes zoster (shingles)

Question 89. What Manifestations Does Cytomegalovirus Cause In Congenital Infections

Answer :

Cytomegalic inclusion disease – spontaneous abortion, CNS damage (deafness, blindness, mental retardation), hepatosplenomegaly, jaundice

Question 90. What Disease Does Cytomegalovirus Cause In Immunocompetent Persons?

Answer :

Mononucleosis infectiosa (heterophile-antibody negative)

Question 91. Describe The Heterophil Antibody Test Used In Epstein-barr Virus Diagnostics?

Answer :

Paul-Bunnel test – in mononucleosis caused by EBV, the serum of the patient agglutinates sheep red blood cells

Question 92. What Is The Mechanism Of Antigenic Drift In Influenza Viruses?

Answer :

Accumulation of point mutations in the hemagglutinin and neuraminidase genes of influenza viruses

Question 93. What Is The Route Of Infection Of Rabies Virus? How Does Rabies Virus Spread In The Infected Body?

Answer :

By the bite of a rabid animal, (rarely by infectious aerosol) spread of the virus in the host – along the axons

Question 94. What Medication Does A Person Need After Exposure To Rabies Virus?

Answer :

Active immunization – human diploid cell vaccine (killed virus) and passive immunization – rabies immune globulin

Question 95. What Is The Portal Of Entry Of Polioviruses? Which Areas Of The Central Nervous System Are Affected By Poliovirus Infection?

Answer :

Oropharynx and gastrointestinal tract damage in motor neurons in the anterior horn of the spinal cord + brain stem

Question 96. Mention At Least 4 Diseases Caused By Coxsackie Viruses?

Answer :

Febrile rashes, herpangina, myocarditis, pericarditis, meningitis, pleurodynia, handfoot- and-mouth disease

Question 97. What Are The Main Modes Of Transmission Of Hbv (hepatitis B Virus) Infection?

Answer :

Sexual contact; perinatally from mother to newborn; by blood or blood products

Question 98. Describe The Active And Passive Prophylaxis Against Hepatitis B?

Answer :

Active immunization: recombinant HBsAg vaccine

Passive immunization: HBIG (hepatitis B immune globulin)

Question 99. Which Hepatitis Viruses Are Acquired Via Parenteral Routes?

Answer :

HBV, HCV, HDV, (HEV)

Question 100. Mention 4 Diseases That Can Be Caused By Adenoviruses?

Answer :

Pharyngitis, pharyngoconjunctival fever, acute respiratory disease, bronchitis, atypical pneumonia, hemorrhagic cystitis, gastrointestinal infection

Question 101. Mention At Least Two Viruses Frequently Causing Pneumonia?

Answer :

RSV, influenza virus A and B, parainfluenza virus, adenovirus, coronavirus (SARS),metapneumovirus

Question 102. What Are The Possible Consequences Of Fetal Infections Caused By Rubella Virus? Specify At Least 3 Of Them?

Answer :

Congenital malformations involving the heart (patent ductus arteriosus, septum defects), the eyes (cataract, glaucoma) and the brain (deafness, mental retardation).

Question 103. Mention 3 Human Prion Diseases?

Answer :

Kuru, Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker syndrome, fatal familial insomnia

Question 104. Mention 3 Nucleoside (or Nucleotide) Type Reverse Transcriptase Inhibitors Used In The Therapy Of Aids?

Answer :

Azidothymidine (zidovudine), abacavir, lamivudine, emtricitabine, tenofovir, dideoxyinosine (didanosine), dideoxycytidine (zalcitabine), stavudine

Question 105. What Is The Principle Of The „highly Active Antiretroviral Therapy” (haart) Currently Used In The Treatment Of Aids?

Answer :

Combination of two nucleoside/nucleotide reverse transcriptase inhibitors (2 NRTI) with either an nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI) or an integrase inhibitor (II) 2 NRTI + NNRTI / PI / II

Question 106. What Does The Term Robovirus Mean? Write An Example For A Robovirus?

Answer :

Robovirus: rodent reservoir (rodent-borne)

Arenaviridae – Lassa, Junin, Machupo, LCM virus; Bunyaviridae – Hantaan virus,

Puumala virus, Sin Nombre virus; Filoviridae – Marburg, Ebola virus

Question 107. What Does The Term Arbovirus Mean? Write An Example For An Arbovirus!

Answer :

Arbovirus: arthropode vector (arthropode-borne);

Flaviviridae – yellow fever, Dengue-fever; Bunyaviridae – Rift-valley fever, Crimean- Congo hemorrhagic fever; etc.

Question 108. Describe The 2 Different Epidemiological Cycles Of Yellow Fever?

Answer :

Jungle yellow fever: reservoir: monkeys; vector: Haemagogus mosquitoes; humans: accidental hosts Urban yellow fever: reservoirs: humans; vectors : Aedes aegypti mosquitoes

Question 109. Mention At Least 4 Opportunistic Infections Characteristic For Aids?

Answer :

Viruses: HSV-1, HSV-2, VZV, CMV, EBV, HHV-8, HPV

Protozoa: Toxoplasma gondii, Pneumocystis jiroveci

Bacteria: Mycobacterium tuberculosis, atypical Mycobacteria, Salmonella septicaemia

Fungi: Candida, Cryptococcus neoformans

Question 110. List At Least Three Viruses Capable Of Causing (meningoencephalitis?

Answer :

Rabies, HSV, VZV, tick-borne encephalitis, Japanese B encephalitis, eastern and western equine encephalitis, mumps, poliovirus, coxsackie virus, echovirus