Microbiology Quiz on Infectious Agents

Microbiology Question Bank Exam 2020/2021

• Question 1: All agents except aztreonam have good Gram-positive activity.

• Question 2: Phylogenetic taxonomy determines DNA relatedness between a strain and a known species.

• Question 3: Both Shigella and Campylobacter have an animal reservoir and can be cultured on bacteriologic media. However, Shigella and Campylobacter are gram-negative bacteria, not gram-positive,

• Question 4: Enterococcus faecalis is least likely to cause UTI, based on lactose-negative colonies and lack of swarming

• Question 5: Some strains of S. aureus produce β-lactamase, making them resistant to penicillin.

• Question 6: Diagnosis of cryptococcal disease involves detecting capsular antigen, the fungus can be dimorphic (hyphae in soil, yeasts in humans). It mainly infects lungs.

• Question 7: Measles and rubella viruses share features such as lifelong immunity following natural infection, they are both enveloped RNA viruses and cause congenital abnormalities

• Question 8: Leptospira organisms associated with Leptospirosis specifically are usually transmitted by human-to-human contact.

• Question 9: Viral neutralizing antibodies are directed against viral proteins found outside the virus particle.

• Question 10: Mycobacterium leprae does not grow on bacteriologic media within the 3-6 weeks timeframe

• Question 11: A newborn whose mother is HBsAg positive should receive both the HBV vaccine and HBIG.

• Question 12: A delayed hypersensitivity reaction is characterized by an infiltrate composed of lymphocytes and macrophages.

• Question 13: Acid-fast stain is used to identify metachromatic granules.

• Question 14: Clostridium Tetani does not grow on blood agar plates in the presence of room air. 

• Question 15: Retroviruses do not have a DNA genome.

• Question 16: Endotoxin is a lipopolysaccharide with a toxic lipid portion.

• Question 17: Aminoglycosides, such as gentamicin and streptomycin, inhibit protein synthesis.

• Question 18: Acute rheumatic fever arises from cross-reactivity of immune response against streptococcal antigens.

• Question 19: Mycoplasma pneumonia is primarily in immunocompetent individuals.

• Question 20: Staphylococci associated with TSS (Toxic Shock Syndrome) are characterized by their appearance in grapelike clusters on a Gram – stained smear.

• Question 21: Yellow fever virus has an animal reservoir.

• Question 22: The bacterial chromosome is a large, circular, double-stranded DNA.

• Question 23: Gram-negative bacteria decolorize during Gram stain due to lipids in their cell wall.

• Question 24: Peptidoglycan is not in the cell wall of animals or fungi. 

• Question 25: Lysogens are when phage DNA is covalently attached to bacterial DNA and thus prevent further phage infection, lytics are not present. 

• Question 26: Most bacterial capsules are polysaccharide. Gram-positive bacteria can have capsules too, but Gram-negative rarely do. 

• Question 27: Herpes simplex virus type 2 is often an important cause of neonatal/infantile infections.

• Question 28: Viral nucleic acid sequences are not used as a definition for viral neutralisation. 

• Question 29: Botulism is caused by a toxin that breaks down lecithin or lecithinase, destroying nerve cells.

• Question 30: Streptococcus pyogenes is characterized by the production of beta-hemolysin and M protein. 

• Question 31: Facultative anaerobes can grow with or without oxygen.

• Question 32: Certain strains of E.coli produce enterotoxin that activates adenylate cyclase.

• Question 33: Arbovirus do not include the following characteristics. 

• Question 34: Typhoid fever is not considered a zoonosis

• Question 35: Neisseria are characterized by being gram-negative diplococci, oxidase-positive, and capable of producing IgA protease.

• Question 36: In AIDS, the Helper T - Suppressor T cell ratio is lower than normal because viral replication destroys helper T cells

• Question 37: Mycobacterium tuberculosis appear as rods in acid-fast stains, not Gram stains, and resist acid alcohol decolorisation after staining with carbolfuchsin. 

• Question 38: Borrelia burgdorferi, the causative agent of Lyme disease is a gram-negative spirochete that is transmitted by a tick bite, it does form serotypes but not as described in the question.

• Question 39: All RNA viruses are not spherical, and some DNA viruses have helical nucleocapsids. 

• Question 40: Bacteroides fragilis; Clostridium botulinum; Corynebacterium diphtheriae and Staphylococcus aureus do not produce exotoxins.

• Question 41: Influenza A virus is more associated with severe pandemics.

• Question 42: Treponema pallidum (the cause of syphilis) is a spiral-shaped rod treated with prolonged penicillin G administration

• Question 43: Gonococcal conjunctivitis in newborns can be prevented by prophylactic use of silver nitrate.

• Question 44: Cytomegalovirus can cause a mononucleosis-like syndrome and is excreted in urine.

• Question 45: The oxidative pentose phosphate pathway exist with other metabolic pathways or in conjunction with the Entner-Doudroff and glycolysis pathways, it is not specific to obligate aerobes. 

• Question 46: Feedback inhibition is a mechanism for fine control of metabolic pathways, with other regulatory mechanisms also provided in the question.

• Question 47: Shigella sonnei is an intestinal mucosa invader.

• Question 48: Resistance to penicillin in bacteria can occur due to reduced affinity of transpeptidases or enzymatic drug modification, it can be by ß-lactamase.

• Question 49: Eastern equine encephalitis can be countered through eradication of the horse reservoir.

• Question 50: Bacterial species are closely related in the important features of organisation.

• Question 51: Poliovirus is a nonenveloped virus with RNA as its genome.

• Question 52: Metronidazole is the drug of choice for anaerobic infections like B. fragilis.

• Question 53: Common cause of gastroenteritis symptoms like nausea, vomitting, and diarrhea is E. coli

• Question 54: The only incorrect statement regarding plague describes humans as the only natural hosts. 

• Question 55: Herpes simplex virus infection in humans is mostly characterised by establishing latent infection.

• Question 56: One process in which DNA is released from a bacterium, taking it up and changing the characteristics of another bacterium is called transformation. 

• Question 57: Identification of bacteria capsules is through preparing mounts with India ink

• Question 58: Protein A of S. aureus binds to the Fc portion of IgG.

• **Question 59:**Arboviruses are not all DNA viruses; there are RNA viruses involved in the arbovirus family

• Question 60: Scalded skin syndrome arises from enzymatic degradation of epidermal desmosomes by S. aureus ,and S. aureus produces coagulation not catalase

• Question 61: Chemical modifications have decreased the frequency of anaphylaxis and increased resistance to stomach acid. 

• Question 62: Rotaviruses are transmitted via respiratory droplets, not through vectors

• Question 63: Flagella is composed of a single protein, flagellin

• Question 64: Escherichia coli is a normal flora organism in the throat, and the most normal flora on the skin is Staphylococcus epidermis.

• Question 65: Herpes simplex virus cannot be eradicated but can be treated in immunocompetent hosts, which is common. 

• Question 66: Synthesis of capsid proteins is not least likely during latent period

• Question 67: Hepatitis A is transmitted by the fecal-oral route, and its presence does not necessarily indicate a chronic infection.

• Question 68: There are some strains of Bacteroides fragilis that are associated with the production of a toxin or fragilin, which is responsible for the diarrheal symptoms

• Question 69: Varicella-zoster virus infections can be characterized by the presence of vesicular lesions on the skin in recurrent and primary forms in humans.

• Question 70: Listeria Monocytogenes can be cultured in human trophoblastic cells

• Question 71: Fluroquinolones do not inhibit protein synthesis.

• Question 72: Neisseria is not a reservoir for any other animal species; these bacteria only exist in humans. 

• Question 73: Chlamydia does not produce toxins or require energy independent of host cells, and thus cannot synthesize independent energy, but is typically intracellular

• Question 74: The bacterial structure that mediates adherence to mucous membranes is pili (also referred to as fimbriae)

• Question 75: Opportunistic infections in AIDS are due to a loss of cell-mediated immunity

• Question 76: Passive Immunization is short-lasting, and does not employ human sensitized cells

• Question 77: Some bacteria grow exponentially and logistically, and do not undergo meiosis

• Question 78: Tetanus spores do not require anaerobic conditions