101+ Top Microbiology Interview Questions (Latest)

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Selection of Interview Questions for the Microbiology section is the finest work, so we prepared a list of important microbiology interview questions for pharmaceutical professionals who are looking for opportunities in the pharma field.

If you have a medical background and are seeking Pharma Microbiologist employment, pharmajobswalkin has outlined the entire procedure for applying for jobs as well as the numerous job roles. If you have a strong background in microbiology, you can apply for a variety of jobs at various companies. So let’s start to learn about the most important Pharma Microbiology Interview Questions and answers for fresher as well as Experienced Professionals.

Note: The below questions are very helpful for freshers as well as for experienced microbiology candidates.

List of Microbiology Interview Questions

Microbiology Interview Questions for Fresher Candidates:

Question 1: Describe the color of Gram-Positive and Gram-Negative Bacteria in a Gram Stained Smear, respectively.
Answer: Dark blue/purple for Gram positives
Red/pink for gram negatives

Question 2: What Are The Three Major Components Of Bacterial Lipopolysaccharide?
Answer: O-specific (polysaccharide) side chain + core polysaccharide+lipid A

Question 3: What Are The Different Bacterial Shapes? Is it possible to write one example for each category?
Answer: Staphylococcus and Streptococcus are spherical coccus.
Clostridium, Corynebacterium, and Gram-negative rods are examples of rods.
Rod with a curved shape: Vibrio \sHelical: Spirochetes are a type of spirochete (Treponema, Borrelia, Leptospira)

Question 4. What Are The Essential Components Of Bacterial Cells? Specify At Least 3?
Answer: Cell membrane, cytoplasm, nucleoid (genome)

Question 5 Which Part Of The Bacterial Cell Carries The Endotoxin?
Answer: Gram-negative bacteria’s outer membrane

Question 6: What Is The Bacterial Capsule’s Role In The Infectious Process?
Answer: Adhesion, antiphagocytic effect

Read: Interview Questions WareHouse in Pharma

Question 7: What Do You Mean When You Say “Obligate Anaerobic Bacteria
Answer: They can only reproduce in the absence of oxygen (under anaerobic conditions). Some of them are immediately killed by oxygen, while others can survive but cannot develop in the presence of oxygen.

Question 8: Give an example of facultative anaerobic bacteria.
Answer: They can replicate both in the presence and absence of oxygen, according to the answer. They perform respiration in aerobic settings and fermentation in anaerobic situations.

Question 9: What Does the Term “Sterilization” Mean?
Answer: Sterilisation is the process of eliminating or killing all microorganisms (including bacterial spores).

Question 10: What are three reliable sterilization methods?
Answer: Autoclaving, hot air oven, gamma radiation, filtration (fluids), and gas sterilization (not acceptable: boiling, pasteurization, or UV!)
Specify the exact set of parameters (temperature and duration) required for optimal autoclave sterilization!
20 minutes at 121°C (at 1 bar pressure)
Using a hot air oven (with circulation), specify an exact set of parameters (temperature and time) for effective disinfection!
60 minutes at 160°C (dry heat)

Question 12: What are the five different types of disinfectants?
Answer: Alcohols, phenol derivatives, detergents, chlorine, iodine, and aldehydes are all examples.

Question 13: What are two different types of disinfectants that act on microbial membrane structures?
Answer: (cationic) detergents (quaternary ammonium compounds)
alcohols containing phenol chemicals (cresol, hexachlorophene, chlorhexidine) (ethanol, isopropanol)

Question 14: What Does It Mean to Be Actively Immunized?
Answer: It refers to the introduction of microbes or microbial products (vaccines) into the human body in order to provide long-term protection against a specific infectious disease.

Question 15: What Does the Term “Passive Immunization” Mean?
Answer: It refers to the injection of prepared antibodies (immune globulins made by animals or humans) into the human body, which provides short-term protection against a specific infectious disease.

Question 16: What Is The Antigen In Vaccines Against Streptococcus Pneumoniae, Haemophilus influenzae, And Neisseria meningitidis Infections?
Answer: Capsular polysaccharide is the correct answer (either alone or conjugated to a carrier protein)

Question 17: What Does The Tuberculosis Vaccine (BCG) Contain?
Answer: Mycobacterium Bovis attenuated in live form (Bacille Calmette-Guerin)

Microbiology Interview Questions for experienced:

Question 18: What Does The Pertussis Vaccine Contain?
Answer : Previously: killed bacteria
Currently, an acellular vaccine (toxoid plus additional purified proteins) is being developed.

Question 19: What Are the Compounds in Diphtheria and Tetanus Vaccines?
Answer: Diphtheria and tetanus toxoid, respectively.

Question 20. Identify the four types of bacterial vaccines based on the antigen’s nature.
Answer: bacterial vaccinations were eliminated by live, attenuated vaccines.
vaccinations against toxoids vaccinations for subunits (capsular polysaccharide or purified protein)

Question 23: What are two neurotoxic bacterial exotoxins?
Answer: Botulinum toxin and tetanus toxin are two examples of toxins.

Question 24: What Is The Mechanism Of Action Of Diphtheria Toxin? Question 24. What Is The Mechanism Of Action Of Diphtheria Toxin?
Answer: ADP-ribosylation of ribosomal EF-2 inhibits protein synthesis in eukaryotic cells (elongation factor-2)

Question 25: What Is the Tetanus Toxin’s Mechanism Of Action?
Answer: Blocking the release of inhibitory neurotransmitters (glycine and GABA) in synapses induces spastic paralysis.

Question 26: Can you name at least three physiologic effects of septic shock (defined by a high level of bacterial endotoxin in the blood)?
Answer: Fever, hypotension, DIC, complement activation, impaired organ perfusion, and hypoglycemia are all effects of Septic Shock.

Question 27: Name two non-essential bacterial organelles that boost virulence! What role does their function play in pathogenicity?
Answer: The capsule has an antiphagocytic action and adheres to tissues.
Fimbriae: Tissue Binding Bacteria are propagated by flagella.

Question 28: What are the four extracellular bacterial enzymes that act as virulence factors?
Answer: Coagulase, streptokinase (fibrinolysis), streptodornase (DNase), hyaluronidase, IgA protease, collagenase, elastase, and urease are the enzymes involved in the breakdown of proteins.

Question 29: What Is A Vector? Explain with an example
Answer: A vector is an arthropod that transmits infection from one person to another or from one animal to another.

Examples. Lyme disease is transmitted by ticks; epidemic typhus is transmitted by louse bites, and malaria is transmitted by mosquito bites.

Question 30: What are two infectious diseases spread by tick bites to humans?
Answer: Tick-borne encephalitis, Lyme disease, tularemia, Rocky Mountain spotted fever, and other diseases can all be caused by ticks.

Question 31. What Is A Reservoir? Explain with an example
Answer: A pathogen’s typical host (human or animal) serves as a constant source of infection for other hosts (such as humans). Yersinia pestis infects rodents while Salmonella typhi infects humans.

Question 33: What Is The Difference Between Infectious Disease Prevalence And Incidence?
Answer: In chronic diseases, it can be distinguished. The term “prevalence” refers to the overall number of diseases that exist (per 100,000 people). The number of new instances in a year is referred to as the incidence (per 100,000 people).

Question 34 in the biomedical waste interview: Why is multi-drug therapy used for tuberculosis?
Answer: To prevent drug-resistant mutants from overgrowing throughout the protracted treatment period (if bacteria resistant to one drug emerge, they are most probably inhibited by the other drugs).

Question 35: What Is Mycobacterium Tuberculosis’s Main Immune Defense Mechanism?
Answer: Activated macrophages

Question 36: Mycobacterium Avium-intracellulare causes which disease? What Kinds Of Patients Are Typically Susceptible To Infection?
Answer: It causes tuberculosis, particularly in immunocompromised persons (such as AIDS patients).

Question 38: Mention one anaerobic and one aerobic bacterium from the skin’s normal flora.
Answer: Staphylococcus epidermidis is an anaerobic bacteria.

Propionibacterium acnes is an anaerobic bacteria.

Question 39: Which three bacterial species are the most common causes of meningitis in babies and children over the age of one month?
Answer: Neisseria meningitides, Haemophilus influenza, and Streptococcus pneumonia are the bacteria that cause meningitis.

Question 40: What Are The Main Symptoms Of Syphilis At Different Stages?
Answer: Primary syphilis causes a non-tender ulcer (hard chancre)

Maculopapular rash on the skin and condylomata lata on the mucous membranes are secondary lesions.

granulomas (gummas), central nervous system involvement (tabes dorsalis, progressive paralysis), cardiovascular problems in the tertiary stage (aortitis, aortic aneurysm)

Question 41: What Are The Two Types Of Antibodies Used In The Syphilis Diagnosis? Give Test Examples To Demonstrate Them.
Answer: RPR, – Reagin (nonspecific antibody), VDRL(flocculation tests)

TPHA – (T. pallidum hemagglutination),

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

Question 42: When comparing the Fta-abs Syphilis Serologic Test to the VDRL Test, what are the benefits and drawbacks?
Answer: While specialized (treponemal) tests like FTA-ABS are more specific, they cannot be used to track therapy efficacy (because the specific antibodies persist even after effective eradication of bacteria)

Question 43: What Symptoms Are Associated With The Late Stages Of Lyme Disease?
Answer: Arthritis, cardiac symptoms (myocarditis, pericarditis), and neurological involvement are the most common conditions (meningitis, peripheral neuropathies)

Question 44: Can you name four bacteria that cause atypical pneumonia?
Answer: Chlamydia pneumoniae.
Chlamydia psittaci is a bacterial infection caused by Chlamydia psitt
Coxiella burnetii is a kind of Coxiella burnetii.
Mycoplasma pneumonia is a bacteria that causes pneumonia.
Legionella pneumophila is a kind of Legionella bacteria.

Question 45: Rickettsia Prowazekii causes which two diseases?
Answer: Brill-Zinsser illness is a recurrent variant of the disease.

Question 46. What Is The Causative Agent Of Epidemic Typhus?
Answer: Rickettsia prowazekii.

Question 47: What is an ‘Endemic Typhus’ Causative Agent?
Answer: Rickettsia typhi is the name of the bacteria.

Question 48: How Can Chlamydiae And Rickettsiae Be Cultivated?
Answer: These bacteria are obligatory intracellular bacteria that can be grown in experimental animals, embryonated eggs, and cell cultures.

Question 49: What are the different serotypes of Chlamydia Trachomatis and what diseases do they cause?
Answer: Trachoma (types A, B, and C) (chronic conjunctivitis)

Infections of the vaginal tract (NGU, PID), inclusion conjunctivitis (types D-K).

Lymphocytic lymphogranuloma venereum (STD) Types (L1-L3)

Question 50: Why Are Penicillins Ineffective Against Mycoplasma Pneumoniae Infections?
Answer: Penicillins are rendered ineffective due to the lack of a cell wall (penicillins inhibit cell wall synthesis)

Question 51: What are the four most common bacteria that cause sexually transmitted diseases (STDs)?
Answer: Treponema pallidum, Neisseria gonorrhoeae, Haemophilus ducreyi, Chlamydia trachomatis, Treponema pallidum, Neisseria gonorrhoeae, Haemophilus ducreyi, Chlamydia trachomatis (Calymmatobacterium granulomatis)

Question 52: What Does Fungal Dimorphism Mean?
Answer: Depending on the environmental conditions, the same species can exist in two morphological forms (yeast or mold) (temperature, nutrients)

Question 53: What are the four types of fungi that cause systemic mycosis?
Answer: Paracoccidioides brasiliensis, Coccidioides immitis, Histoplasma capsulatum, Blastomyces dermatitidis

Question 54: What are the three species that cause opportunistic fungal infections?
Answer: Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Mucor spp., and Rhizopus spp. are the bacteria that cause fungal infections.

Medical Microbiology Interview Questions:

Below are the important Questions that have already been asked many times in Interviews:

Question 60: Which Species Are Malaria’s Causative Agents?
Answer: Plasmodium vivax, Plasmodium ovale, Plasmodium malaria, Plasmodium falciparum

Question 61: What Is Malaria’s Laboratory Diagnosis?
Answer: Blood smears stained with Giemsa. A thin smear is used to identify the species and a thick smear is used to screen for the agent.

Question 62: How Can Amebic Dysentery Be Diagnosed?
Answer: E.Histolytica cysts and trophozoites from faeces microscopically demonstrated

Question 63: How Can Trichomonas vaginalis Infection Be Diagnosed?
Answer: Protozoa can be seen directly in a wet mount or stained smear of clinical specimens (vaginal, urethral, or prostatic secretions).

Question 64: How Can Intestinal Taeniasis Be Diagnosed?
Answer: In faeces, there is evidence of distinctive proglottids and eggs (ova).

Question 65: What are two worm species that migrate through the human lungs in the larval stage?
Answer: Ascaris lumbricoides, Ancylostoma duodenale is a kind of Ancylostoma and Strongyloides stercoralis Necator americanus.

Question 66: How Can You Tell If You Have An Enterobius Infection?
Answer: Demonstration of ova (eggs) obtained from the perianal skin (Scotch tape technique). Certainly not from faeces!

Question 67: Mention 4 Tissue Infecting Filarial Nematodes
Answer: Wuchereria bancrofti, Loa loa, Dracunculus medinensis, and last one is Onchocerca volvulus.

Read: Interview Questions Regulatory Affairs

Question 68: What Causes Human Fasciola Hepatica Infection?
Answer: By consuming encysted larvae through aquatic plants (Rarely: by eating raw sheep liver containing adult worms)

Question 69. What Disease Is Caused If Humans Are Contaminated Per Os With Taenia Solium Eggs?
Answer: Human cysticercosis. it is a type of encysted larvae in the brain, eyes, etc.

Question 70. Mention 2 Helminths Whose Larvae Enter The Human Body By Penetrating The Intact Skin.
Answer: Schistosoma, Ancylostoma duodenal, Necator americanus, and last, Strongyloides stercoralis

Question 71. What Are The Superior, And The Middle Hosts Of Taenia Saginata, Respectively?
Answer: A definitive host is a human
The intermediate host is a cattle

Question 72. What Are The Superior, And The Middle Hosts Of Taenia Solium, Respectively?
Answer: A definitive host is a human
The intermediate host is a 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 develop in the soil for a few days to evolve infectious (embryonated)

Question 76. Is Autoreinfection Possible In Strongyloide Stercoralis Infection? If Yes, When?
Answer: Yes, particularly in immunosuppression (for example in the case of AIDS)

Question 77. Is Autoreinfection Possible In Enterobius Vermicularis Infection? If Yes, When?
Answer: Yes, the eggs become contagious in a few hours, and autoinfection may happen (especially in children)

Question 78. Mention 3 DNA Virus Families Containing No Envelope.
Answer: Papillomaviridae, Parvoviridae, and Adenoviridae

Question 79. Mention 3 DNA Virus Families Containing Envelope.
Answer: Hepadnaviridae, Poxviridae, and Herpesviridae.

Question 80: Which Virus Family Is Known For Its Double-Stranded Rna Genome?
Answer: Reoviridae is the correct answer.

Question 83. Which DNA Virus Uses Reverse Transcription In Its Replication?
Answer: HBV iHepadnaviridae

Question 84. What Are The Serious Complications Of HSV Infection In Newborns?
Answer: Disseminated infections, encephalitis, infections of the skin, eyes, and mouth

Question 85. Which Viruses Are Acyclovir Susceptible? What Is The Drug’s Mechanism Of Action?
Answer: Alpha herpesviruses (HSV1, HSV2, VZV); viral DNA polymerase inhibitor and DNA chain terminator

Question 86: Why Is Acyclovir Toxic Only To Cells Infected With Alpha-Herpesviruses?
Answer: These viruses have their own thymidine kinase enzymes, which are required for the drug’s activation (phosphorylation). The medication is not activated by cellular thymidine kinase.

Question 87. In Which Cells Do Herpes Simplex Viruses Establish Latent Infection?
Answer: Sensory ganglion cells (trigeminal or sacral ganglia)

Question 88: What Is A Late Complication Of Childhood Chickenpox (Years After Acute Infection)?
Answer: Herpes zoster (shingles)

Question 89. What Symptoms Does Cytomegalovirus Cause In Congenital Infections?
Answer: CNS impairment (deafness, blindness, mental retardation), hepatosplenomegaly, and jaundice are all symptoms of cytomegalic inclusion disease.

Read: Pharma Coating Interview Questions

Question 90: What Is The Disease Caused By Cytomegalovirus In Immunocompetent People?
Answer: Infectious mononucleosis (heterophile-antibody negative)

Question 91: Describe the Heterophil Antibody Test used in Epstein-Barr Virus Diagnosis.
Answer: In mononucleosis caused by EBV, the patient’s serum agglutinates sheep red blood cells in the Paul-Bunnel test.

Question 92. What Is The Mechanism Of Antigenic Drift In Influenza Viruses?
Answer: Point mutations in the hemagglutinin and neuraminidase genes of influenza viruses accumulate over time.

Question 94. What Medication Does A Person Need After Being Exposed To The Rabies Virus?
Answer: Passive immunization – rabies immune globulin and active immunization – human diploid cell vaccine (killed virus)

Question 95: What Is The Poliovirus Entry Portal? Poliovirus Infection Affects Which Parts Of The Central Nervous System?
Answer: Motor neurons in the anterior horn of the spinal cord + brain stem are damaged in the oropharynx and gastrointestinal tract.

Microbiology Interview Questions for Food Departments:

Question 96: Can you name at least four diseases caused by Coxsackieviruses?
Answer: Febrile rashes, herpangina, myocarditis, pericarditis, meningitis, pleurodynia, and hand-foot-and-mouth disease are all symptoms of coxsackievirus

Question 97: What Are The Most Common Modes Of HBV (Hepatitis B Virus) Transmission?
Answer: perinatally from mother to infant; via blood or blood products

Question 98: What Is The Difference Between Active And Passive Hepatitis B Prophylaxis?
Answer: Recombinant HBsAg vaccine is an active immunization method.
HBIG is a passive immunisation (hepatitis B immune globulin)

Microbiology Interview Questions for Lab Technician:

Interview Questions Microbiology for lab technicians are given below:

Question 99: How do you distinguish between procaryotic and eukaryotic cells?
Ans. The lack of a membrane-bound nucleus and other cell organelles distinguishes prokaryotic cells from eukaryotic cells. When compared to eukaryotic cells, they are substantially tiny (about 0.2-2.0 mm in diameter) (Typically 10-100 mm in diameter). Prokaryotic cells typically have a complex cell wall, whereas eukaryotic cells either don’t have one or have one that is relatively simple.

Question 100: How much magnification do you need to see microorganisms?
Ans. To examine and focus on microorganisms, a basic magnification of 40x is required. The larger cells can be seen easily, while the exact details are hidden. Bacteria appear as tiny specks with minimal detail at 100x magnification. For studying minute details, 400x magnification is required.

Question 101: What microbial properties should be determined during a microorganism’s study and investigation?
Ans. Morphological traits, chemical composition, cultural, metabolic, genetic, antigenic qualities, pathogenicity, and ecological aspects should all be considered while studying microorganisms.

Question 102: How useful are pure cultures?
Ans. Pure cultures are required for laboratory and research work as test agents for various studies or as taxonomic reference strains. They allow researchers to investigate the properties of a particular species.

Question 103: What is the most popular laboratory sterilization technique? Could you please explain the technique?
Ans. The autoclave is the most popular form of sterilizing used in laboratories, and it works on the idea of destroying bacteria using moist heat. It kills the vegetative and spore phases of microbial cells using high pressure and temperature (121°C at 15 psi for 15 minutes).

Question 104: Define endospores. Is it possible to call it a reproduction method?
Ans. Bacillus, Clostridium, Sporosarcina, and Thermoactinomyces create endospores, which are thick-walled, highly refractile entities produced one per cell. Desiccation, staining, disinfection, and many sterilizing treatments have no effect on them. A spore is a metabolically inactive form that can germinate and create a vegetative cell under the right conditions. It is not, however, a technique of reproduction.

Question 105: Why is nutrient broth regarded as a universal bacterial growth medium?
Answer: Nutrient broth is a universal development medium because it contains substances like beef extract, peptone, and yeast extract, which give carbohydrates, organic nitrogen compounds, water-soluble vitamins, and salts.

Question 106: Why is gram stain one of bacteriology’s most essential and extensively used stains?
Ans. In most cases, the Gram stain is the first step in identifying a bacterial organism. Gram staining distinguishes bacteria by the chemical and physical properties of their cell walls, which contain peptidoglycan, which is present as a thick layer in gram-positive bacteria and as a thin layer in gram-negative bacteria. It is a useful diagnostic tool in both clinical and research settings.

Final Thought on Microbiology Interview Questions:

If you are a fresher or experienced person, then definitely the above Interview Questions for Microbiology candidates are going to be very helpful. As all the above questions are already asked in most organizations, pharmaceuticals, food, and even in government jobs.

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