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C. Year 3: Core Drugs > Microorganisms > Flashcards

Microorganisms Flashcards

1
Q

What is the mechanism of action of Penicillins?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - Inhibit DNA synthesis
5 - Inhibit RNA synthesis

A

3 - Inhibit protein wall synthesis

  • binds to PBB permanently
  • PBB unable to perform transpeptidation
  • cell wall becomes weak and unstable
  • cell wall will fail when bacteria try to multiply

PBB = penicillin binding protein

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2
Q

What is the mechanism of action of β-lactam antibiotic and β-lactamase inhibitors? (select 2)

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - Inhibit DNA synthesis
5 - Inhibit inhibit B-lactamases

A

3 - Inhibit protein wall synthesis
5 - Inhibit inhibit B-lactamases
- function of clavulanic acid

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3
Q

What is the mechanism of action of Glycopeptide antibiotics?

1 - Inhibits formation of the peptidoglycans (NAG and NAM) subunits and destabilises cell wall
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - Inhibit DNA synthesis
5 - Inhibit RNA synthesis

A

1 - Inhibits formation of the peptidoglycans (NAG and NAM) subunits and destabilises cell wall

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4
Q

What is the mechanism of action of Cephalosporins antibiotics?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - binds and inactivates penicillin binding proteins
5 - Inhibit RNA synthesis

A

4 - binds and inactivates penicillin binding proteins

  • bacterial cell wall becomes unstable and cell lyses
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5
Q

What is the mechanism of action of Tetracyclines antibiotics?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - binds and inactivates penicillin binding proteins
5 - Inhibit RNA synthesis

A

2 - Inhibit 30S subunit of ribosomes

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6
Q

What is the mechanism of action of Macrolides antibiotics?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - binds and inactivates penicillin binding proteins
5 - Inhibit RNA synthesis

A

1 - Inhibit 50S subunit of ribosomes

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7
Q

What is the mechanism of action of Aminoglycosides antibiotics?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - binds and inactivates penicillin binding proteins
5 - Binds to 30S subunit causing misreading of mRNA

A

5 - Binds to 30S subunit causing misreading of mRNA

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8
Q

What is the mechanism of action of Quinolones antibiotics?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - binds and inactivates penicillin binding proteins
5 - inhibit DNA gyrase

A

5 - inhibit DNA gyrase
- topoisomerase II and IV
- DNA cannot unwind and cell will eventually die

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9
Q

What is the mechanism of action of Nitroimidazole antibiotics?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - release nitrosa free radicals
5 - inhibit DNA gyrase

A

4 - release nitrosa free radicals
- damages DNA
- without function DNA the cell cannot replicate and will die

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10
Q

What is the mechanism of action of the antibiotic Chloramphenicol?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - binds and inactivates penicillin binding proteins
5 - inhibit DNA gyrase

A

1 - Inhibit 50S subunit of ribosomes
- inhibites peptidyl transferase

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11
Q

A 29-year-old female undergoes a sub total thyroidectomy. Five days post operatively the wound becomes erythematous and discharges pus. What is the most likely causative organism?

1 - Streptococcus pyogenes
2 - Haemophilus influenzae
3 - Pseudomonas aeruginosa
4 - Staphylococcus aureus
5 - Proteus mirabilis

A

4 - Staphylococcus aureus
- most common cause of wound infection

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12
Q

A 49-year-old woman presents to her GP with dysuria, urinary frequency and malaise. The GP sends a urine sample for culture and sensitivities, which is reported as growing E. Coli which is resistant to ampicillin. What is the mechanism of resistance?

1 - Beta-lactamase production
2 - Carbapenemase production
3 - Efflux pump removing antibiotic from bacteria
4 - Mutation in the gene encoding the target site
5 - Production of protective biofilm

A

1 - Beta-lactamase production

  • The mechanism of resistance of penicillins is producing beta-lactamase which cleaves the beta-lactam ring of the antibiotic
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13
Q

A 45-year-old man presents with a cough that started as a dry cough and has become productive of blood flecked sputum. He has also had a fever and nausea for the last 5 days. On questioning, he tells you that 2 weeks ago he was on holiday at a lovely cottage that had a hot tub which he spent a lot of time in. A sputum sample is sent and microbiology grows a gram-negative coccobacillus. What is the likely causative organism?

1 - Legionella pneumophila
2 - Streptococcus pneumoniae
3 - Mycoplasma pneumoniae
4 - Candida albicans
5 - Listeria monocytogenes

A

1 - Legionella pneumophila

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14
Q

A consultant physician is delivering a presentation on his groundbreaking research on antibiotics to a group of peers. The consultant explains that the antibiotics he is working on inhibit protein synthesis by acting on the 30s ribosomal unit.

Which one of the following antibiotics is he referring to?

1 - Trimethoprim
2 - Rifampicin
3 - Metronidazole
4 - Tetracyclines
5 - Quinolones

A

4 - Tetracyclines

Tetracyclines inhibit protein synthesis by binding to 30S subunit blocking binding of aminoacyl-tRNA

Tetracyclines (doxycycline, lymecycline) inhibit protein synthesis by acting on the 30s ribosomal unit

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15
Q

While on placement on a urology ward you get a call from microbiology about the bacteria they have identified in a urine sample from an elderly male you are treating for urosepsis. What is the most common bacteria responsible for a urinary tract infection?

1 - Staphylococcus saprophyticus
2 - Klebsiella pseudomonas
3 - Chlamydia
4 - Escherichia coli
5 - Candida albicans

A

4 - Escherichia coli

A urinary tract infection (UTI) is an infection that involves any part of the urinary tract. This can be a lower UTI where the infection affects the urethra or bladder or an upper UTI where it involves the ureters and kidneys (pyelonephritis).

Escherichia coli is the cause of 80-85% of community-acquired urinary tract infections, with Staphylococcus saprophyticus and being the cause in 5-10%. Candida albicans, Klebsiella pseudomonas and Chlamydia are far less common causes of an urinary tract infection.

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16
Q

A 52-year-old man from Afganistan is visiting family in the UK. He visits the doctor concerned that his feet have been periodically tingling and numb and he is very concerned. He has a history of tuberculosis and type 2 diabetes mellitus. Which of his medications may be responsible for his presentation?

1 - Pyrazinamide
2 - Isoniazid
3 - Ethambutol
4 - Sitagliptin
5 - Metformin

A

2 - Isoniazid

Isoniazid is the most likely cause of the numbness and tingling in the patient’s hands and feet.

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17
Q

A 45-year-old man from Pakistan is visiting family in the UK. He visits the doctor concerned that he may be having blood in his urine, though he isn’t sure if it is more red or orange in colour. He has a history of tuberculosis for which he is being treated with quadruple therapy. Which of his medications may be responsible for his presentation?

1 - Isoniazid
2 - Ethambutol
3 - Pyrazinamide
4 - Rifampicin
5 - Streptomycin

A

4 - Rifampicin

All of these drugs can be used in the treatment of tuberculosis, but Rifampicin is know for causing a red-orange discoloration of bodily fluids including urine, tears, and sweat.

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18
Q

Several days later from a cut in the thigh the patient becomes febrile and develops gross swelling of the left lateral thigh. When pressure is applied to the affected area crackles are heard. A diagnosis of gas gangrene is suspected. What is the mechanism of the bacterial toxin causing this patient’s clinical signs?

1 - ADP-ribosylation of elongation factor II
2 - Binds the Fc region of IgA
3 - Degradation of phospholipids
4 - Inhibition of presynaptic GABA release
5 - Superantigen binding MHC II

A

3 - Degradation of phospholipids

Degradation of phospholipids is the correct answer. The patient’s presentation, characterised by deep tissue crepitus surrounding a penetrating wound, is consistent with gas gangrene. Gas gangrene is caused by the organism Clostridium perfringens, which releases an alpha-toxin, a lecithinase enzyme, that degrades phospholipids.

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19
Q

A 65-year-old male with known HIV infection presents to the emergency department with a headache that has worsened over the past three weeks. He denies neck stiffness but has felt generally unwell, reporting a fever and malaise. He is known to have poor compliance with his anti-retroviral medications.

A lumbar puncture is performed whereby a sample of cerebrospinal fluid is sent for culture. The sample stains positive with an India ink stain. What is the most likely organism causing this patient’s presentation?

1 - Cryptococcus neoformans
2 - Streptococcus pneumoniae
3 - Neisseria meningitidis
4 - Toxoplasma gondii
5 - Pneumocystis jirovecii

A

1 - Cryptococcus neoformans

  • The presentation here is of subacute meningitis, which can often lack the classical feature of neck stiffness that is usually present in more acute disease. Given the patient’s HIV status, the potential for cryptococcal disease should be considered.
  • Cryptococcus neoformans is a fungal infection that is an AIDS-defining illness and most commonly causes sub-acute meningitis in those with HIV. India ink stain is the specific investigation used to visualise the organism and make the diagnosis. Treatment can then follow with agents such as amphotericin B and flucytosine often used
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20
Q

A woman presents with thin grey discharge which has a fishy odour. She is subsequently diagnosed with bacterial vaginosis. Her doctor explains that this is caused by an overgrowth of normal bacterial flora and that many bacteria can be responsible for this condition. The presence of which bacterium would call for a reconsideration of her diagnosis?

1 - Peptostreptococci
2 - Mobiluncus
3 - Trichomonas vaginalis
4 - Gardnerella vaginalis
5 - Mycoplasma hominis

A

3 - Trichomonas vaginalis

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21
Q

A father brings his 5-year-old daughter to see her GP. She has an acute illness manifesting as mouth ulcers, fever, and vesicles on her palms and feet. The GP diagnoses this as hand, foot and mouth disease. What pathogen can cause this condition?

1 - Coxsackievirus A16
2 - Cytomegalovirus
3 - Human herpesvirus 6
4 - Human immunodeficiency virus
5 - Streptococcus pyogenes

A

1 - Coxsackievirus A16

  • Along with enterovirus, coxsackievirus can cause hand, foot and mouth disease. This is a self-limiting and common condition in paediatrics which is managed conservatively and does not require isolation from school
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22
Q

A previously well 27-year-old male is currently in hospital with a prolonged stay due to treatment-resistant osteomyelitis. He is now on day 7 of clindamycin. He feels relatively well in himself but has noticed some bruising on his arms. The patients bloods are normal except a raised WBC and prolonged pro-thrombin time. What is the most likely diagnosis?

1 - Chronic kidney disease
2 - Haemophilia A
3 - Leukaemia
4 - Thrombocytopenia
5 - Vitamin K deficiency

A

5 - Vitamin K deficiency

  • vitamin K deficiency may occur after prolonged use of broad-spectrum antibiotics (clindamycin) by eliminating the gut flora
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23
Q

A 58-year-old man presents to his GP after noticing an abnormal patch of mucosa at the back of his throat. He thinks this has gradually increased in size over the last few weeks. He is known to have a chronic hepatitis C infection. On examination, he has bilateral cervical lymphadenopathy.

The GP refers him via the urgent cancer pathway for suspected oropharyngeal cancer. What is a risk factor for developing this type of cancer?

1 - Epstein-Barr virus
2 - Hepatitis C
3 - Human herpes virus 8
4 - Human papillomavirus 16/18
5 - Human papillomavirus 6/11

A

4 - Human papillomavirus 16/18
- can cause:

Cervical cancer
Anal cancer
Penile cancer
Vulval cancer
Oropharyngeal cancer

24
Q

A 4-year-old boy presents to his GP with his mother. He has been coughing profusely for the last 2 weeks. Occasionally, after prolonged periods of coughing, his mother reports that he will start retching or vomiting. He has not received any childhood investigations. During the consultation, the boy begins coughing extensively with intermittent inspiratory gasps between each bout of coughing. What culture medium is required to confirm the likely causative organism?

1 - Blood agar
2 - Bordet-Gengou agar
3 - Chocolate agar
4 - Lowenstein-Jensen agar
5 - Tellurite agar

A

2 - Bordet-Gengou agar

  • Bordet-Gengou agar is correct. This patient has a history suggestive of whooping cough, given the prolonged history of cough and post-percussive retching and vomiting. The gram-negative bacteria Bordetella pertussis is the organism responsible for whooping cough. It is cultured using the Bordet-Gengou agar.
25
Q

A group of consultant surgeons are meeting at a symposium. The chef preparing the canapes has an infection on his finger. Approximately 40 minutes after eating the canapes the group are struck down with severe vomiting. What is the most likely underlying explanation for this process?

1 - Presence of enterotoxin from Staphylococcus aureus in the food
2 - Presence of enterotoxin from Streptococcus pyogenes in the food
3 - Infection with Campylobacter jejuni
4 - Presence of enterotoxin from Clostridium perfringens in the food
5 - Infection with Shigella soneii

A

1 - Presence of enterotoxin from Staphylococcus aureus in the food

  • Staphylococcus aureus may release an enterotoxin, this is preformed and thus will typically result in rapid onset of symptoms in affected individuals.
26
Q

A 60-year-old man presents to the clinic with breathlessness. An urgent chest X-ray is arranged. Sputum cultures reveal that he has pneumonia. He is started on erythromycin. What is the mechanism of action of erythromycin?

1 - Inhibit 50S subunit of ribosomes
2 - Inhibit 30S subunit of ribosomes
3 - Inhibit protein wall synthesis
4 - Inhibit DNA synthesis
5 - Inhibit RNA synthesis

A

1 - Inhibit 50S subunit of ribosomes

27
Q

A 27-year-old female gives birth to a baby boy at 35 weeks gestation. His weight is small for gestational age, and his APGAR scores (color, 2) heart rate, 3) reflexes, 4) muscle tone, and 5) respiration) are consistently low. His physical examination is otherwise unremarkable. The mother does not recall any illness during pregnancy or any sick contacts, and lives at home with her husband and two cats.

He is admitted to the neonatal intensive care unit, where investigations are carried out. Ophthalmological examination demonstrates chorioretinitis, and neuroimaging shoes intracranial calcifications scattered throughout the brain. What is the most likely diagnosis?

1 - Congenital CMV infection
2 - Congenital listeria infection
3 - Congenital rubella
4 - Congenital syphilis
5 - Congenital toxoplasmosis

A

5 - Congenital toxoplasmosis

  • Classic triad of congenital toxoplasmosis = chorioretinitis, intracranial calcifications, hydrocephalus
  • Toxoplasma gondii is a ubiquitous protozoan parasite, infection with which is generally asymptomatic in immunocompetent hosts. It is one of the ‘ToRCHeS’ infections, and pregnant women can contract the infection through ingestion of raw or undercooked meat, and classically while handling cat litter. Congenital toxoplasmosis occurs through transplacental transmission and classically manifests as the triad of chorioretinitis, hydrocephalus, and intracranial calcifications.
28
Q

A 4-year-old boy presents to your general practice clinic. The boy has had a low-grade fever for the last 2 days but has now developed mouth ulcers and a rash today. On examination, you notice that mouth ulcers are covering the tongue and inside of the cheek. On the boy’s hands and feet you notice flat pink papules which blanch on pressure. What viruses are the two most likely to cause this presentation?

1 - Adenovirus and rhinovirus
2 - Coxsackie A16 and enterovirus
3 - Herpes simplex virus types 1 and 2
4 - Respiratory syncytial virus and parainfluenza virus
5 - Rhinovirus and coronavirus

A

2 - Coxsackie A16 and enterovirus

29
Q

Which of the following most commonly causes early-onset neonatal sepsis in the UK?

1 - Escherichia coli
2 - Group B Streptococcus
3 - Listeria monocytogenes
4 - Coagulase-negative staphylococci
5 - Pseudomonas aeruginosa

A

2 - Group B Streptococcus

30
Q

Which test is used to determine which bacteria are Gram + or Gram -?

1 - gram staining
2 - ziehl neelsen stain
3 - acid fast
4 - giemsa stain
5 - chocolate agar

A

1 - gram staining

  • Gram + have thick peptidoglycan layer that dye binds with
  • Gram - have thin peptidoglycan between the surface and plasma membrane so dye cannot bind with peptidoglycan
31
Q

Which test is regarded as the world’s standard diagnostic technique for malaria’s plasmodium (parasite) and classifying lymphomas?

1 - gram staining
2 - ziehl neelsen stain
3 - acid fast
4 - giemsa stain
5 - chocolate agar

A

4 - giemsa stain

  • eosin stains parasite nucleus red
  • methylene blue stains cytoplasm blue
32
Q

The giemsa stain is regarded as the world’s standard diagnostic technique for malaria’s plasmodium (parasite) and classifying lymphomas. Which 2 other microorganisms is the giemsa stain used for?

1 - Trypanosomes
2 - Staphylococci
3 - Neisseria gonorrhoeae
4 - Chlamydia trachomatis

A

1 - Trypanosomes
4 - Chlamydia trachomatis
- causes Chlamydia

33
Q

Which test is used for staining the the fungi Cryptococcus neoformans?

1 - periodic acid-Schiff stain
2 - ziehl neelsen stain
3 - acid fast
4 - india ink
5 - chocolate agar

A

1 - india ink

  • can cause Cryptococcal meningitis is an infection caused by the fungus Cryptococcus after it spreads from the lungs to the brain. The symptoms of cryptococcal meningitis include:

Headache
Fever
Neck pain
Nausea and vomiting
Sensitivity to light
Confusion or changes in behavior

34
Q

Which test is used for staining the Tropheryma whippelii that can lead to a gastrointestinal disease causing malabsorption called Whipples disease?

1 - periodic acid-Schiff stain
2 - ziehl neelsen stain
3 - acid fast
4 - giemsa stain
5 - chocolate agar

A

1 - periodic acid-Schiff stain

35
Q

Which test is used for staining:

  • Pneumocystis jiroveci
  • Legionella pneumophilia
  • Helicobacter pylori

1 - periodic acid-Schiff stain
2 - silver stain
3 - acid fast
4 - giemsa stain
5 - chocolate agar

A

2 - silver stain

  • Pneumocystis jiroveci = fungi that affects immunocompromised patients
  • Legionella pneumophilia = gram negative bacteria that can cause a severe form of pneumonia
  • Helicobacter pylori = can lead to peptic ulcers
36
Q

Which test is used for staining Mycobacteria, which causes TB?

1 - periodic acid-Schiff stain
2 - ziehl neelsen stain
3 - acid fast
4 - giemsa stain
5 - chocolate agar

A

2 - ziehl neelsen stain

37
Q

Bacteria classed as cocci in shape can be both Gram + and Gram -. Which of the following is a Gram + cocci?

1 - staphylococci
2 - Neisseria meningitidis
3 - Neisseria gonorrhoeae
4 - Moraxella catarrhalis

A

1 - staphylococci
- over 30 different strains
- most common is Staphylococcus aureus found on skin

38
Q

Bacteria classed as cocci in shape can be both Gram + and Gram -. Which of the following is a Gram + cocci?

1 - Escherichia coli
2 - Neisseria meningitidis
3 - Neisseria gonorrhoeae
4 - Streptococci

A

4 - Streptococci
- can be categorised in types A, B, C and G

39
Q

Streptococci is classed as a Gram + cocci. Streptococci can be further categorised into types A, B, C and G. Although type A is the most common, they do not tend to cause significant disease. Which of the following conditions is NOT causes by Streptococci A bacteria?

1 - Strep throat
2 - Scarlet fever
3 - Impetigo
4 - Sepsis
5 - Post-Streptococcal Glomerulonephritis

A

4 - Sepsis

40
Q

Streptococci is classed as a Gram + cocci. Streptococci can be further categorised into types A, B, C and G. Although not as common as type A Streptococci, type B typically causes more severe infections. Which of the following conditions is NOT causes by Streptococci B bacteria?

1 - scarlet fever
2 - sepsis
3 - pneumonia
4 - meningitis

A

1 - scarlet fever

41
Q

Streptococci is classed as a Gram + cocci. Streptococci can be further categorised into types A, B, C and G. Although not as common as type A Streptococci, type B typically causes more severe infections, such as sepsis, pneumonia and meningitis. Which of the following patients is at risk of developing a severe infection if they contract Streptococci B?

1 - older patients
2 - newborn babies
3 - pregnant women
4 - all of the above

A

4 - all of the above

42
Q

Bacteria classed as cocci in shape can be both Gram + and Gram -. Which of the following is NOT classed as a Gram - cocci?

1 - Staphylococci
2 - Neisseria meningitidis
3 - Neisseria gonorrhoeae
4 - Moraxella catarrhalis

A

1 - Staphylococci

43
Q

All of the following are classed as Gram - bacilli, which are rods. Which of the following is NOT a Gram + bacilli (rods)?

1 - Actinomyces
2 - Escherichia coli
3 - Bacillus anthracis (anthrax)
4 - Clostridium
5 - Diphtheria
6 - Listeria monocytogenes

A

2 - Escherichia coli
- this is Gram + baccilli (rod)

REMEMBER ABCD L

  • Diphtheria = Corynebacterium diphtheriae
44
Q

All of the following are classed as Gram + bacilli, which are rods. Which of the following is NOT a Gram - bacilli (rods)?

1 - Escherichia coli
2 - Haemophilus influenzae
3 - Clostridium
4 - Pseudomonas aeruginosa
5 - Salmonella sp.
6 - Shigella sp.
7 - Campylobacter jejuni

A

3 - Clostridium
- this is a Gram - baccilli (rod)

45
Q

Staphylococcus aureus is a Gram + cocci. Which of the following is NOT true about Staphylococcus aureus?

1 - Facultative anaerobe
2 - Gram-positive coccus
3 - Haemolysis on blood agar plates
4 - Catalase negative

A

4 - Catalase negative
- it is catalase positive

  • catalase is an enzyme produced by some bacteria
  • catalase detoxifies hydrogen peroxide creating water and oxygen gas
  • bubbles appear = catalase positive
46
Q

Catalase is an enzyme produced by some bacteria. Testing if a bacteria is catalase positive or negative helps identify the organism. What does catalase do?

1 - enzyme that can damage/lyse RBCs
2 - enzyme that can damage/lyse WBCs
3 - enzyme that detoxifies hydrogen peroxide
4 - enzyme that helps produce films

A

3 - enzyme that detoxifies hydrogen peroxide

  • hydrogen peroxide is what host cells produce to kill microorganisms
47
Q

Haemolysis on blood agar plates can be used to identify the organisms. What do bacteria do to cause haemolysis?

1 - damage/lyse RBCs
2 - enzyme that can damage/lyse WBCs
3 - enzyme that detoxifies hydrogen peroxide
4 - enzyme that helps produce films

A

1 - damage/lyse RBCs

48
Q

Staphylococcus aureus is a Gram + cocci. Which 2 of the following does it commonly cause?

1 - cutaneous infections
2 - pneumonia
3 - abscesses
4 - neonatal sepsis

A

1 - cutaneous infections
3 - abscesses

49
Q

Streptococcus pyogenes is a Gram + cocci. Which of the following is NOT true about Staphylococcus aureus?

1 - Catalase positive
2 - Cocci that form chains
3 - Group A Streptococcus
4 - Haemolysis on blood agar plates

A

1 - Catalase positive
- catalase negative

  • causes scarlet fever through production of exotoxin A
50
Q

Escherichia coli is a Gram - bacilli (rod). Which of the following is NOT true about Escherichia coli?

1 - Facultative anaerobe, non-sporing
2 - all E.coli are commensals and are not dangerous
3 - responsible for enteritis and large volume diarrhoea with fever
4 - resistant to many antibiotics
5 - able to produce beta-lactamases

A

2 - all E.coli are commensals and are not dangerous

  • E. coli 0157 produces lethal toxins resulting in haemolytic-uraemic syndrome
51
Q

Haemolytic-uraemic syndrome (HUS) can be caused byEscherichia coli, a Gram - bacilli (rod), specifically 0157. How does this occur?

1 - patient develops bloody diarrhoea
2 - shiga like toxin enters circulation
3 - toxin binds to endothelium cells in glomerulus of kidney, inducing cell apoptosis
4 - blood clots form and block blood vessels in the kidneys
5 - RBCs break down, reduced eGF and increased urea in the blood
6 - all of the above

A

6 - all of the above

52
Q

Which of the following is NOT true about Campylobacter jejuni?

1 - Curved, Gram-negative bacteria
2 - non-sporulating bacteria
3 - catalase positive
4 - one of the commonest causes of diarrhoea worldwide, and likely cause of right iliac fossa pain with diarrhoea
5 - self limiting, but can be treated using quinolones are often rapidly effective.

A

3 - catalase positive
- if is not catalase positive

53
Q

Helicobacter pylori is a Gram - helix-shaped rod, microaerophilic bacteria. Which of the following is NOT correct about Helicobacter pylori?

1 - produces catalase that derives energy from hydrogen released by intestinal bacteria
2 - flagellated and mobile
3 - carriers of the cag A gene may cause ulcers
4 - secretes urease that breaks down gastric urea to produce bicarbonate
5 - bicarbonate can neutralise the gastric acid and allow colonisation
6 - colonises the gastric antrum and irritates resulting in increased gastrin release and higher levels of gastric acid causing gastric and duodenal ulcers

A

1 - produces catalase that derives energy from hydrogen released by intestinal bacteria

  • produces hydrogenase that can derive energy from hydrogen released by intestinal bacteria
54
Q

Rifampicin is an antibiotic drug that can be used to treat suspected, or reduce the risk of developing meningitis. What is the mechanism of this drug?

1 - Inhibition of DNA gyrase
2 - Inhibition of DNA-dependent RNA polymerase
3 - Inhibition of mycolic acid synthesis
4 - Inhibition of peptidoglycan synthesis
5 - Inhibition of topoisomerase IV

A

2 - Inhibition of DNA-dependent RNA polymerase

  • preventing transcription of DNA into mRNA
55
Q

Which of the following is a curved gram - rod shaped bacteria causing rice water diarrhoea, with no blood, with sunken eyes and reduced skin turgor?

1 - Escherichia coli
2 - Shigella
3 - Salmonella
4 - Vibrio cholerae
5 - Giardia lamblia

A

4 - Vibrio cholerae
- none of the other microorganisms cause acute diarrhoea

  • Escherichia coli = Gram - bacilli (rods) and causes bloody diarrhoea
  • Shigella = Gram - rod shaped and causes bloody diarrhoea
  • Salmonella = Gram - rod shaped
  • Giardia lamblia = parasite

C. Year 3: Core Drugs (125 decks)

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