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Question 1
Incorrect
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A patient presents with a fever, headache and neck stiffness. A CSF sample of someone with meningococcal meningitis typically shows:
Your Answer: Low glucose
Correct Answer: All of the above
Explanation:CSF analysis typically shows:
cloudy turbid appearance
raised WCC – predominantly neutrophils
high protein
low glucose (typically < 40% of serum glucose)
Gram-negative diplococci seen under microscopy -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 2
Incorrect
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You suspected typhoid disease in a patient who had recently returned from South America and presented to the emergency department with fever, constipation, and a rose spot rash. Which of the following antibiotics will be administered to this patient?
Your Answer: Metronidazole
Correct Answer: Cefotaxime
Explanation:Typhoid fever, often known as enteric fever, is a potentially fatal multi-systemic sickness caused predominantly by Salmonella enterica serotype typhi and, to a lesser extent, paratyphi A, B, and C.
Cefotaxime is the first-line treatment for typhoid fever (or ceftriaxone). In cases of mild or moderate sickness caused by multiresistant pathogens, azithromycin is an option. If the bacterium is sensitive, ciprofloxacin is an option.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 3
Incorrect
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A 71-year-old man treated with antibiotics for a chest infection returns with a profuse, offensive smelling diarrhoea. A diagnosis of Clostridium difficile diarrhoea is made after investigations.
Which antibiotic is associated with the greatest risk of causing Clostridium Difficile diarrhoea?
Your Answer: Tetracycline
Correct Answer: Ciprofloxacin
Explanation:Clostridium difficile, a Gram-positive, anaerobic, spore forming bacteria is present in the gut of approximately 3% of healthy adults (2012 UK HPA estimates). Following use of broad spectrum antibiotics, which alter normal gut flora, Clostridium difficile infection (CDI) occurs. About 80% of Clostridium Difficile infections are seen in people over the age of 65 and its main clinical features are:
Abdominal cramps, severe bloody and/or watery diarrhoea, offensive smelling diarrhoea, and fever.CDI is the most severe consequence of antibiotic treatment and is a major cause of morbidity and mortality.
Risk for CDI has been found to be greatest with clindamycin followed by fluoroquinolones Tetracyclines are not associated with risk for CDI. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 4
Incorrect
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A newborn baby is born by vaginal delivery to a mother who has a Chlamydia infection and who is started on treatment after the delivery. The neonate subsequently develops an infection also.
Which one of these is the most common neonatal manifestation of Chlamydia trachomatis infection?Your Answer: Meningitis
Correct Answer: Conjunctivitis
Explanation:Conjunctivitis is the most common neonatal manifestation of Chlamydia trachomatis infection. The second commonest neonatal manifestation is pneumonia
Ophthalmia neonatorum refers to any conjunctivitis in the newborn period, irrespective of causative organism. Presently, chlamydia is the single most common cause, accounting for up to 40% of cases. Ophthalmia neonatorum caused by chlamydia typically presents 5 to 14 days after birth with unilateral or bilateral watery discharge that progressively becomes more copious and purulent. There is no associated risk of ulceration and perforation, and the eyes are less inflamed.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 5
Correct
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A 70-year-old man has severe diarrhoea one week after taking co-amoxiclav for a chest infection. The diarrhoea is yellow in colour and smell is offensive.
What is the SINGLE MOST likely causative organism?
Your Answer: Clostridium difficile
Explanation:Clostridium difficile, a Gram-positive, anaerobic, spore forming bacteria is present in the gut of approximately 3% of healthy adults (2012 UK HPA estimates). Following use of broad spectrum antibiotics, which alter normal gut flora, Clostridium difficile associated diarrhoea (CDAD) occurs.
About 80% of Clostridium difficile infections are seen in people over the age of 65 and its main clinical features are:
Abdominal cramps, severe bloody and/or watery diarrhoea, offensive smelling diarrhoea, and fever. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 6
Correct
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A 22-year-old man comes to the emergency department with a human bite injury to his hand received from a punch during a fight 3 hours earlier outside a bar. On closer inspection, you discover bite marks on his first and second knuckles. Which of the following is the best treatment option for this patient:
Your Answer: Oral co-amoxiclav for 7 days
Explanation:Even if there is no evidence of infection, prophylactic antibiotics should be administered for all human bite wounds that are less than 72 hours old. The first-line therapy is 7 days of co-amoxiclav. In penicillin-allergic people, metronidazole + doxycycline is an option. Streptococcus spp., Staphylococcus aureus, Haemophilus spp., Eikenella corrodens, Bacteroides spp., and other anaerobes are the most prevalent organisms found in human bites.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 7
Correct
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A 22-year-old student presents with a painful, red and itchy right eye. On examination, there is mild erythema of palpebral conjunctiva, and follicles are visible on eversion of the eyelid. Lid oedema is evident, and you can also see a few petechial subconjunctival haemorrhages. The eye appears watery, and there is no purulent discharge. He has recently recovered from a mild upper respiratory tract infection.
Which of these is the most likely causative organism?
Your Answer: Adenovirus
Explanation:The most frequent cause of red eye is conjunctivitis. It is caused by inflammation of the conjunctiva which can be infective or allergic and accounts for about 35% of all eye problems presenting to general practice.
Viral conjunctivitis is commonly caused by adenoviruses and it is the most common infectious conjunctivitis.
The common bacterial causes of conjunctivitis are Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus.
The clinical features of infective conjunctivitis include:
Acute onset of conjunctival erythema
Feeling ‘grittiness’, ‘foreign body’ or ‘burning’ sensation in the eye.
Watering and discharge which may cause transient blurring of visionFeatures of viral conjunctivitis include: watery and non-purulent eye discharge, lid oedema, follicles present on eyelid eversion, petechial subconjunctival haemorrhages and pseudomembranes may be seen on the tarsal conjunctival surfaces.
This patients features are consistent with a viral aetiology, and the most likely causative organism is adenovirus,
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 8
Incorrect
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Which of the following serology results is consistent with chronic hepatitis B infection:
Your Answer: HBsAg positive and anti-HBc IgM positive
Correct Answer: HBsAg positive and anti-HBc IgG positive
Explanation:Disease state vs Serology
Acute hepatitis: BHBsAg, HBeAg, anti-HBc IgM
Chronic hepatitis B (low infectivity): HBsAg (>6/12), anti-HBe, anti-HBc IgG
Chronic hepatitis B (high infectivity): HBsAg (>6/12), HBeAg, anti-HBc IgG
Cleared infection: Anti-HBs, anti-HBe, anti-HBc IgG
Vaccinated: Anti-HBs -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 9
Correct
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Clostridium difficile primarily causes which of the following infectious diseases:
Your Answer: Pseudomembranous colitis
Explanation:Clostridium difficile causes pseudomembranous colitis, an acute inflammatory diarrhoeal disease and an important cause of morbidity and mortality in hospitals. Gas gangrene is primarily caused by Clostridium perfringens. Tetanus is caused by Clostridium tetani. Toxic shock syndrome may be caused by Staphylococcus aureus or Streptococcus pyogenes. Necrotising fasciitis is most commonly caused by Streptococcus pyogenes but has a multitude of causes.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 10
Incorrect
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A 73-year-old woman arrives at the emergency department 48 hours after being discharged from the hospital after a two-week stay for sepsis treatment. She has fever, productive cough with thick green sputum, and shortness of breath. An X-ray shows left lower lobe pneumonia. Which of the bacteria listed below is more likely to be the causative agent:
Your Answer: Haemophilus influenzae
Correct Answer: Pseudomonas aeruginosa
Explanation:Hospital-acquired pneumonia (HAP), or nosocomial pneumonia, is a lower respiratory infection that was not incubating at the time of hospital admission and that presents clinically 2 or more days after hospitalization. Pneumonia that presents sooner should be regarded as community acquired pneumonia. VAP refers to nosocomial pneumonia that develops among patients on ventilators. Ventilator-associated pneumonia (VAP) is defined as pneumonia that presents more than 48 hours after endotracheal intubation.
Common bacteria involved in hospital-acquired pneumonia (HAP) include the following [10] :
Pseudomonas Aeruginosa
Staphylococcus aureus, including methicillin-susceptible S aureus (MSSA) and methicillin-resistant S aureus (MRSA)
Klebsiella pneumoniae
Escherichia coli -
This question is part of the following fields:
- Infections
- Microbiology
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Question 11
Correct
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An 8-year-old boy was brought to the emergency room with complaints of a rash and fever that have been present for the past 3 days. Upon history taking and observation, it was noted that the rash started behind the ears and then spread to the face and body. The presence of coryzal symptoms, dry cough, and conjunctivitis was also observed.
What is most likely the diagnosis of the case presented above?Your Answer: Measles
Explanation:The measles virus is an enveloped virus classified in the genus
Morbillivirus.
Measles is highly contagious and spreads by aerosol. Initial replication takes place in the mucosal cells of the respiratory tract; measles virus then replicates in the local lymph nodes and spreads systemically. The virus circulates in the T and B cells and monocytes, until eventually the lungs, gut, bile duct, bladder, skin, and lymphatic organs are involved. After an incubation period of 7 to 10 days, there is an abrupt onset, with symptoms of sneezing, runny nose and cough, red eyes, and rapidly rising fever. About 2 to 3 days later, a maculopapular rash appears on the head and trunk. Koplik spots, lesions on the oral mucosa consisting of irregular red spots, with a bluish white speck in the centre, generally appear 2 to 3 days before the rash and are diagnostic.Measles is easily diagnosed clinically, so few requests for laboratory identification are made. The virus is fragile and must be handled carefully. The specimens of choice are from the nasopharynx and urine, but the virus can only be recovered from these sources in the early stages of infection. The virus grows on PMK cells, causing the formation of distinctive spindle-shaped or multinucleated cells.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 12
Correct
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A 23-year-old has a known diagnosis of HIV. Blood is sent to the laboratory for tests.
AIDS be diagnosed at a CD4 counts below?Your Answer: 200 cells/mm 3
Explanation:A normal CD4 count ranges from 500-1000 cells/mm3.
At CD4 count of less than 350 cells/mm3 treatment with anti-retroviral therapy should be considered.
At a CD4 count of >200 cells/mm3 AIDS is diagnosed.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 13
Correct
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A 37-year-old man presents with breathlessness on exertion and dry cough, fever for the past 2 days and bilateral pleuritic chest pain.
He had been diagnosed with HIV and commenced on HAART but due to side effects, his compliance has been poor over the last few months.
On examination you note scattered crackles and wheeze bilaterally, cervical and inguinal lymphadenopathy, and oral thrush. At rest his oxygen saturation is 97% but this drops to 87% on walking. There is perihilar fluffy shadowing seen on his chest X-ray.
Which of these organisms is the most likely causative organism?
Your Answer: Pneumocystis jirovecii
Explanation:All of the organisms listed above can cause pneumonia in immunocompromised individuals but the most likely cause in this patient is Pneumocystis jirovecii.
It is a leading AIDS-defining infection in HIV-infected individuals and causes opportunistic infection in immunocompromised individuals. HIV patients with a CD4 count less than 200 cells/mm3 are more prone.
The clinical features of pneumonia caused by Pneumocystis jirovecii are:
Fever, chest pain, cough (usually non-productive), exertional dyspnoea, tachypnoea, crackles and wheeze.
Desaturation on exertion is a very sensitive sign of Pneumocystis jirovecii pneumonia.Chest X-ray can show perihilar fluffy shadowing (as is seen in this case) but can also be normal.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 14
Incorrect
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A 63 year old lady presents to ED with a persistent cough and red currant jelly sputum. She has a history of chronic alcohol abuse and has an X-ray which demonstrates a cavitating pneumonia. The most likely causative pathogen is:
Your Answer: Streptococcus pneumoniae
Correct Answer: Klebsiella pneumoniae
Explanation:One of the results of Klebsiella pneumoniae is pneumonia that is usually a very severe infection. It is characterised by thick, bloody sputum (red currant jelly sputum), and is associated with complications like lung abscess, cavitation, necrosis, empyema and pleural effusions.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 15
Correct
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You received a patient with a 2-day history of diarrhoea and vomiting. Later, after examination, the patient was found to have progressive symmetric descending flaccid paralysis, initial development of blurred vision, dysphagia, and weakness of the upper limbs. The patient is apyrexial and his observations are all normal. Which of the following pathogens is responsible for the said symptoms?
Your Answer: Clostridium botulinum
Explanation:A botulism infection results in neuroparalysis caused by the neurotoxin generated by Clostridium botulinum.
Food-borne botulism symptoms often appear 12-36 hours after ingestion of the toxin-containing food and may include nausea, vomiting, stomach discomfort, and diarrhoea at first. The most common neurological pattern is an acute onset of bilateral cranial neuropathies with symmetric declining weakening.
Other distinguishing characteristics include the absence of fever, the absence of cognitive abnormalities, the presence of a normal heart rate and blood pressure, and the absence of sensory defects.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 16
Correct
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A 33-year-old female, who recently returned from a trip to Bangladesh, presents to the infectious diseases clinic with complaints of productive cough with blood-stained sputum, night sweats, and weight loss for the past one month. Based on the history and examination findings, you suspect pulmonary tuberculosis.
Which ONE of the following investigations is most appropriate to make a diagnosis of active tuberculosis?Your Answer: Sputum for acid-fast bacilli smear
Explanation:Multiple investigations may be done to establish a diagnosis of active tuberculosis. In this case, sputum for acid-fast bacilli would be the best option as it can be done immediately, give fast results, and promptly initiate treatment. Three-morning sputum samples are collected and tested for acid-fast bacilli using gram staining.
Blood culture would yield results in tuberculous bacteraemia and would be less sensitive than sputum testing.
A chest X-ray would not differentiate active tuberculosis from an old infection in which the Ghon complex has formed, and the body’s immune reaction contains the Mycobacterium tuberculosis bacteria.
Mantoux test shows the presence of antibodies to tuberculosis and may be positive if the patient has had a previous infection or been vaccinated against tuberculosis.
A CT chest would also be unable to differentiate between an active infection and the findings of old tuberculosis infection.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 17
Incorrect
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Regarding dermatophytes, which of the following statement is CORRECT:
Your Answer: First-line treatment is usually with oral terbinafine.
Correct Answer: Diagnosis is made from microscopy and culture of skin scrapings, hair samples or nail clippings.
Explanation:Diagnosis is made from microscopy and culture of skin scrapings, hair samples or nail clippings depending on the site of infection. The lesions of ringworm typically have a dark outer ring with a pale centre. Tinea capitis is ringworm affecting the head and scalp. Spread is via direct skin contact. Treatment is usually topical, oral antifungals are reserved for refractory infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 18
Incorrect
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Which of the following virulence factors of E. coli is important for attachment to host epithelial cells in the pathogenesis of urinary tract infections:
Your Answer: Toxin A
Correct Answer: Pili
Explanation:Escherichia coli is the most common cause of urinary tract infection. Uropathic strains are characterised by pili with adhesion proteins that bind to specific receptors on the urinary tract epithelium. The motility of E. coli aids its ability to ascend the urethra into the bladder or ascend the ureter into the kidney.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 19
Incorrect
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A blood culture was performed from a sample taken from a patient. It was noted that a Gram-negative coccus organism was grown.
Among the following microorganisms, which is considered an example of a Gram-negative coccus?Your Answer: Campylobacter jejuni
Correct Answer: Neisseria menigitidis
Explanation:Staphylococcus aureus = Gram-positive coccus
Bacillus cereus = Gram-positive bacillus
Campylobacter jejuni = Gram-negative bacillus
Escherichia coli = Gram-negative bacillusIn Gram staining, crystal violet is a purple stain that is used to stain the bacteria first. The stained bacteria are decolorized and then stained with a red stain, which is safranin. Bacteria with thick cell walls keep the purple stain and are called Gram-positive. Thin-walled bacteria are easily decolorized so when safranin, the red stain, is placed on the organisms, they become red or Gram-negative.
Neisseria species appear as Gram-negative diplococci because they form pairs and their adjacent ends are flattened that is why they are also described to have a coffee-bean or kidney-bean shape. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 20
Correct
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Anatomical barriers to infection include all of the following EXCEPT:
Your Answer: Mucociliary escalator in the gastrointestinal tract
Explanation:Anatomical barriers to infection include:tight junctions between cells of the skin and mucosal membranesthe flushing action of tears, saliva and urinethe mucociliary escalator in the respiratory tract (together with the actions of coughing and sneezing)the acidic pH of gastric and vaginal secretionsthe acidic pH of the skin (maintained by lactic acid and fatty acids in sebum)enzymes such as lysozyme found in saliva, sweat and tearspepsin present in the stomachbiological commensal flora formed on the skin and the respiratory, gastrointestinal and genitourinary tracts which protect the host by competing with pathogenic bacteria for nutrients and attachment sites and by producing antibacterial substances
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This question is part of the following fields:
- Microbiology
- Principles
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Question 21
Correct
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A 35-year-old man is feeling unwell following his return from a business trip. He is diagnosed with a vector transmitted disease.
Which of these organisms is commonly spread by vector-borne transmission?Your Answer: Borrelia burgdorferi
Explanation:Borrelia burgdorferiis, primarily spread by ticks and lice, is a zoonotic, vector-borne organism that causes Lyme disease.
Neisseria meningitidis and Bordetella pertussis are droplet borne infections (airborne particle > 5 µm)
Vibrio cholerae and Ascaris lumbricoides are spread by the faeco-oral route
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 22
Incorrect
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A 32-year old male patient has been diagnosed with meningococcal meningitis and was given appropriate treatments. Because he is a family man, he fears that he might transmit the infection to the rest of his family members.
The causative agent of meningococcal meningitis is spread via what mode of transmission?Your Answer: Blood transfusion
Correct Answer: Respiratory droplet route
Explanation:N. meningitidis, the causative agent of meningococcal meningitis, is considered both a commensal and a pathogen. It can be found in the surfaces of mucous membranes such as the nasopharynx and oropharynx. With this, it can be transmitted from a carrier to a new host via respiratory droplet secretions.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 23
Incorrect
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Which statement concerning aerosol transmission is true?
Your Answer: They usually only infect the upper respiratory tract and not the lower respiratory tract
Correct Answer: They can be spread via ventilation systems in hospitals
Explanation:Aerosols are airborne particles less than 5 µm in size containing infective organisms.
They usually cause infection of both the upper and/or lower respiratory tract.
The organisms can remain suspended in the air for long periods and also survive outside the body.
They can be transmitted through the ventilation systems and can spread over great distances.
Some examples of organisms transmitted by the aerosol route include: Varicella zoster virus, Mycobacterium tuberculosis and measles virus
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 24
Incorrect
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A 32-year-old woman presents with abdominal pain and bloody diarrhoea that has been going on for 3 days.
Among the following microorganisms, which is considered to be a cause of infectious bloody diarrhoea?Your Answer:
Correct Answer: Entamoeba histolytica
Explanation:The following are organisms that are capable of producing acute, bloody diarrhoea:
– Campylobacter jejuni
– Escherichia coli O157:H7
– Salmonella species
– Shigella species
– Yersinia species
– Entamoeba histolyticaOther E. coli strains, Giardia, Vibrio, and other parasites are associated with watery, but not bloody, diarrhoea.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 25
Incorrect
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Regarding Cryptococcus neoformans, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: Patients with complement deficiency are at particular risk of infection.
Explanation:Cryptococcus neoformans typically causes infection in patients with lymphoma, those taking steroid or cytotoxic therapy, those with T-cell deficiency e.g. AIDS and those with intense exposure, such as pigeon fanciers.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 26
Incorrect
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One of the following pathogens is a conditional pathogen:
Your Answer:
Correct Answer: Neisseria meningitidis
Explanation:Obligate pathogens include Mycobacterium TB, HIV, Treponema pallidum, and Neisseria gonorrhoeae. Neisseria meningitidis, on the other hand, is a conditional pathogen.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 27
Incorrect
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A 30-year-old man presents with diarrhoea, fever, vomiting, and abdominal cramps. A stool culture was ordered and showed growth of Salmonella spp.
Among the following serotypes of Salmonella spp., which is considered to be the most common cause of salmonella gastroenteritis?Your Answer:
Correct Answer: Serotype D
Explanation:A common cause of gastroenteritis, Salmonella enteritidis, and Salmonella typhi, which causes enteric fever, are both group D. Therefore, serotype D Salmonella species are most commonly associated with gastroenteritis.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 28
Incorrect
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A 20-year-old male patient lives in a travelling community and has never received any vaccinations. He presents to you with fever.
Which of these statements concerning indications and contraindications for vaccination is TRUE?
Your Answer:
Correct Answer: Inactivated vaccines are safe in pregnancy
Explanation:All vaccines are contraindicated in individuals with: A confirmed anaphylactic reaction to a previous dose of the vaccine or a vaccine containing the same antigens.
A confirmed anaphylactic reaction to a component in the vaccine e.g. neomycinThere is no evidence that vaccinating pregnant women with inactivated vaccine or toxoids harms the woman or foetus.
The current protocol is that a child with history of egg allergy can be safely vaccinated with Fluenz tetra. However, if they had a previous severe anaphylaxis to egg requiring intensive care, then Flenz tetra is contraindicated.
BCG, yellow fever or oral typhoid vaccinations are not safe in HIV positive patients.
The normal times recommended for immunization of full-term babies should also be applied to premature infants and correction for gestational age should not be implemented.
Concurrent antibiotic therapy is not a contraindication to vaccination.
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This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 29
Incorrect
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Which of the following is NOT a typical complication associated with mumps:
Your Answer:
Correct Answer: Subacute sclerosing panencephalitis
Explanation:Complications of mumps include meningitis, post meningitis deafness, encephalitis, pancreatitis, orchitis and oophoritis. Subacute sclerosing panencephalitis is a complication typically associated with measles infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 30
Incorrect
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You are planning on starting antibiotic therapy for a patient with a diagnosis of gonorrhoea.
Which of these is the MOST appropriate antibiotic combination?Your Answer:
Correct Answer: Ceftriaxone and azithromycin
Explanation:Currently, ceftriaxone in combination with azithromycin or doxycycline is the combination of antibiotics used in the treatment of gonorrhoea.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 31
Incorrect
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Which of the following microbes is spread by a vector:
Your Answer:
Correct Answer: Plasmodium falciparum
Explanation:The female Anopheles mosquito is the vector for Plasmodium falciparum transmission. Treponema pallidum is transmitted through sexual transmission or direct skin contact. Clostridium perfringens is spread by direct skin contact or through oral-faecal route. The oral-faecal pathway is how Vibrio cholerae spreads. Mycoplasma tuberculosis is spread via the airborne route.
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This question is part of the following fields:
- Microbiology
- Principles
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Question 32
Incorrect
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Which of the following microbes binds strongly to CD4 antigen:
Your Answer:
Correct Answer: HIV
Explanation:HIV mainly infects CD4+ T helper cells. Viral replication results in progressive T-cell depletion and impaired cell-mediated immunity with subsequent secondary opportunistic infections and increased risk of malignancy. B-cell function is also reduced as a result of lack of T-cell stimulation.
HIV is not a notifiable disease. -
This question is part of the following fields:
- Microbiology
- Principles
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Question 33
Incorrect
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A 7-days-old neonate is taken to the emergency department. She's pyretic, lethargic, and unresponsive, and her fontanelle has bulged. Antibiotics are started, and a lumbar puncture reveals Gram-negative rods. Which pathogen is most likely to be the cause:
Your Answer:
Correct Answer: Escherichia coli
Explanation:Among neonates, group B streptococci (GBS) are the most commonly identified causes of bacterial meningitis, implicated in roughly 50% of all cases. Escherichia coli(Gram-negative rods) accounts for another 20%. Thus, the identification and treatment of maternal genitourinary infections is an important prevention strategy.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 34
Incorrect
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Which of the following statements is considered correct regarding Klebsiella infections?
Your Answer:
Correct Answer: Klebsiella spp. are non-motile
Explanation:Klebsiella is a Gram-negative, rod-shaped, non-motile bacteria. The absence of motility distinguishes Klebsiella spp. from most other members of the family Enterobacteriaceae.
K. pneumoniae is the most commonly isolated species and has the distinct feature of possessing a large polysaccharide capsule. The capsule offers the organism protection against phagocytosis and antimicrobial absorption,
contributing to its virulence.Colonization of gram-negative bacilli in the respiratory tracts of hospitalized patients, particularly by K. pneumoniae, increases with the length of hospital stay. It is a frequent cause of lower respiratory tract infections among hospitalized patients and in immunocompromised hosts such as newborns,
elderly patients, and seriously ill patients on respirators. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 35
Incorrect
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A 17-year-old student presents with a headache and petechial rash. A diagnosis of meningitis was suspected, with a causative agent of Neisseria meningitidis.
Which of the following statements is considered correct regarding Neisseria meningitidis?Your Answer:
Correct Answer: The antiphagocytic polysaccharide capsule is the main determinant of its pathogenicity
Explanation:N. meningitidis is a Gram-negative cocci and can be found as a commensal as well as an invasive pathogen. It is an important etiologic agent of endemic and epidemic meningitis and meningococcaemia and rarely pneumonia, purulent arthritis, or endophthalmitis. N. meningitidis has also been recovered from urogenital and rectal sites as a result of oral-genital contact. Meningococcal carriage, usually involving nonencapsulated strains, may cause an increase in protective antibody against the pathogenic strains. Of the 12 meningococcal encapsulated serogroups, A, B, C, Y, and W-135 account for most cases of disease in the world. N. meningitidis possesses a polysaccharide capsule that is antiphagocytic and serves as an important virulence factor.
It can be found on the mucosal surfaces of the nasopharynx and oropharynx in 30% of the human population. The organism is transmitted by close contact with respiratory droplet secretions from a carrier to a new host. Only a few newly colonized hosts develop meningococcal disease, with the highest incidence being found in infants and adolescents.
The quadrivalent vaccine Menactra is a polysaccharide-protein conjugated vaccine with antigens to serogroups A, C, Y, and W-135. This conjugate vaccine is licensed for people 2 to 55 years old. This vaccine does not protect against meningitis caused by serogroup B because group B polysaccharide is a very poor immunogen in humans.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 36
Incorrect
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A patient with a diagnosis of HIV presents with a fever, sore throat, and general malaise and you are concerned the patient may have an AIDS defining illness.
Which one of these, according to the CDC definition, would mean a patient infected with HIV has AIDS?
Your Answer:
Correct Answer: CD4 T-cell percentage of total lymphocytes of less than 15%
Explanation:According to the CDC definition, a patient co-infected with HIV can be diagnosed with AIDS if he or she has:
A CD4 T-cell count of less than 200 cells/mm3 or;
A CD4 T-cell percentage of total lymphocytes of less than 15% or;
An AIDS defining infectionA Streptococcal throat infection is not an AIDS defining infection.
A normal CD4 count ranges from 500-1000 cells/mm3. A CD4 (not CD8) count of less than 200 cells/mm3 is AIDS defining.
The CD4 count can vary from day to day and depending upon the time that the blood test is taken. It can also be affected by the presence of other infections or illnesses. Treatment with anti-retroviral therapy should be considered at CD4 count of less than 350 cells/mm3.
Serum concentrations of the p24 antigen (the viral protein that makes up most of the core of the HIV) are usually high in the first few weeks after human immunodeficiency virus (HIV) infection and testing for p24 antigen is therefore a useful way of diagnosing very early infection.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 37
Incorrect
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A 26 year old male presents to emergency room with a 2 day history of burning pain when passing urine, accompanied by a green urethral discharge. Gonorrhoea is suspected. The first line antibiotic for this condition is which of the following?
Your Answer:
Correct Answer: Ceftriaxone
Explanation:When there is a high suspicion of gonorrhoea from clinical features, empiric treatment should be commenced whilst waiting for laboratory confirmation.
The first line treatment for uncomplicated anogenital and pharyngeal disease includes ceftriaxone 500 mg IM (single dose) + azithromycin 1 g orally as a single dose. This covers concomitant chlamydia infection. For all people who have been treated for gonorrhoea, a test of cure is recommended -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 38
Incorrect
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Which patient group are most commonly associated with infection with Klebsiella spp:
Your Answer:
Correct Answer: Hospitalised patients
Explanation:Klebsiella spp. are facultatively anaerobic Gram-negative rods, found in the normal intestinal and respiratory flora. These organisms are usually opportunistic pathogens that cause nosocomial infections, most commonly pneumonia and UTI.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 39
Incorrect
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A 21-year-old student presents with fever, headache, malaise, fatigue, and muscle aches after returning from a trip to India. A diagnosis of malaria was suspected.
Which of the following statements is considered correct regarding malaria?Your Answer:
Correct Answer: Haemoglobinuria and renal failure following treatment is suggestive of Plasmodium falciparum
Explanation:Malaria results from infection with single-celled parasites belonging to the Plasmodium genus. Five species of Plasmodium are known to cause disease in humans: P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi.
Chloroquine remains the mainstay of treatment for uncomplicated vivax malaria.
The female Anopheles mosquito serves as the biologic vector and definitive host.
A complication of infection with P. falciparum is blackwater fever, a condition characterized by haemoglobinuria.
Plasmodium ovale has the longest incubation period, which can be up to 40 days. Plasmodium falciparum has a shorter incubation period of 7-14 days.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 40
Incorrect
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Which of the following could denote a diagnosis of acquired immunodeficiency syndrome (AIDS) in a patient infected with HIV:
Your Answer:
Correct Answer: CD4 count < 200 cells/uL
Explanation:A diagnosis of AIDS can be made in a patient infected with HIV if the patient has a CD4 count < 200 cells/uL, or an AIDS-defining illness. Antiretroviral treatment should be considered in patients with CD4 counts < 350 cells/uL.
Oral candidiasis is not an AIDS defining illness – candidiasis of the bronchi, trachea, lungs or of the oesophagus is an AIDS defining illness.
A positive p24 antigen test seen in early HIV infection and does not indicate the development of AIDS.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 41
Incorrect
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Among the following infectious diseases, which is typically considered to have an incubation period of 3 weeks and longer?
Your Answer:
Correct Answer: Infectious mononucleosis
Explanation:Infectious mononucleosis is caused by Epstein-Barr virus (EBV). The incubation period for EBV varies from 2 weeks to 2 months.
The usual incubation period for rubella is 14 days; with a range of 12 to 23 days.
Gonorrhoea has a short incubation period of approximately 2 to 7 days.
The mumps virus can be isolated from infected saliva and swabs rubbed over the Stensen’s duct from 9 days before onset of symptoms until 8 days after parotitis appears.
Scarlet fever, which appears within 1 to 2 days after bacterial infection, is characterized by a diffuse red rash that appears on the upper chest and spreads to the trunk and extremities. The rash disappears over the next 5 to
7 days and is followed by desquamation. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 42
Incorrect
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A 55-year-old woman with history of gastritis and reflux esophagitis tested positive for Helicobacter pylori infection.
Which of the following statements regarding Helicobacter pylori is considered true?Your Answer:
Correct Answer: It is helix shaped
Explanation:Helicobacter pylori is a curved or helix-shaped, non-spore forming, Gram-negative, microaerophilic bacteria. It is motile, having multiple flagella at one pole. It has a lipopolysaccharide component in its outer membrane.
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 43
Incorrect
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Regarding the varicella zoster virus, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Contracting chickenpox infection while pregnant is associated with a higher risk of developing varicella pneumonitis.
Explanation:Chickenpox infection in neonates, adults/adolescents and pregnant women is associated with more severe disease. Varicella zoster pneumonitis typically occurs in pregnant women or immunocompromised individuals and is associated with a high mortality. A live attenuated-virus vaccine is available and recommended for non-immune healthcare workers but is not part of the routine childhood immunisation schedule. Antiviral treatment is not typically recommended in childhood chickenpox but is indicated for shingles.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 44
Incorrect
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A 26-year-old woman is currently 9 weeks pregnant. Upon interview and history taking, she mentioned that she visited a friend whose child had just been diagnosed with slapped cheek disease.
If the mother contracts an illness during pregnancy, which among the following is not known to cause fetal abnormalities?Your Answer:
Correct Answer: Hepatitis A
Explanation:Hepatitis A usually doesn’t pose a special risk to a pregnant woman or her baby. Maternal infection doesn’t result in birth defects, and a mother typically doesn’t transmit the infection to her baby. HAV is almost always transmitted by the faecal-oral route and is usually acquired through close personal contact or via contaminated food.
When a woman has chickenpox in the first 20 weeks of pregnancy, there is a 1 in 50 chance for the baby to develop a set of birth defects. This is called the congenital varicella syndrome. It includes scars, defects of muscle and bone, malformed and paralyzed limbs, small head size, blindness, seizures, and intellectual disability.
TORCH Syndrome refers to infection of a developing foetus or newborn by any of a group of infectious agents. “TORCH” is an acronym meaning (T)toxoplasmosis, (O)ther Agents, (R)ubella (also known as German Measles), (C)ytomegalovirus, and (H)erpes Simplex.
Infection with any of these agents may cause a constellation of similar symptoms in affected newborns. These may include fever; difficulties feeding; small areas of bleeding under the skin, causing the appearance of small reddish or purplish spots; enlargement of the liver and spleen (hepatosplenomegaly); yellowish discoloration of the skin, whites of the eyes, and mucous membranes (jaundice); hearing impairment; abnormalities of the eyes; and other symptoms and findings. -
This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 45
Incorrect
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Which of the following problems is associated with Helicobacter pylori infection?
Your Answer:
Correct Answer: Gastric malignancy
Explanation:Helicobacter pylori is a ubiquitous organism that is present in about 50% of the global population. Chronic infection with H pylori causes atrophic and even metaplastic changes in the stomach, and it has a known association with peptic ulcer disease. The most common route of H pylori infection is either oral-to-oral or faecal-to-oral contact.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 46
Incorrect
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A patient is diagnosed with a Klebsiella infection.
Which SINGLE statement regarding Klebsiella infections is true?Your Answer:
Correct Answer: Klebsiella spp are an important cause of ventilator-associated pneumonia
Explanation:Klebsiellais a genus of non-motile,Gram-negative, rod-shaped bacteriawith a prominent polysaccharide-based capsule. They are routinely found in the nose, mouth and gastrointestinal tract as normal flora, however, they can also behave as opportunistic pathogens.
Infections with Klebsiella spp. areusually nosocomial. They are an important cause of ventilator-associated pneumonia (VAP), urinary tract infection, wound infection and bacteraemia. Outbreaks of infections with Klebsiellaspp. in high-dependency units have been described and are associated with septicaemia and high mortality rates. Length of hospital stay and performance of invasive procedures are risk factors forKlebsiellainfections.
Primary pneumonia withKlebsiella pneumoniaeis a rare,severe, community-acquired infection associated with a poor outcome.
Klebsiella rhinoscleromatis causes a progressive granulomatous infection of the nasal passages and surrounding mucous membranes. This infection is mainly seen in the tropics.
Klebsiella ozanae is a recognised cause of chronic bronchiectasis.
Klebsiella organisms are resistant to multiple antibiotics including penicillins. This is thought to be a plasmid-mediated property. Agents with high intrinsic activity againstKlebsiellapneumoniaeshould be selected for severely ill patients. Examples of such agents include third-generation cephalosporins (e.g cefotaxime), carbapenems (e.g. imipenem), aminoglycosides (e.g. gentamicin), and quinolones (e.g. ciprofloxacin). These agents may be used as monotherapy or combination therapy. Aztreonam may be used in patients who are allergic to beta-lactam antibiotics.
Species with ESBLs (Extended spectrum beta-lactamase) are resistant to penicillins and also cephalosporins such as cefotaxime and ceftriaxone
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This question is part of the following fields:
- Microbiology
- Specific Pathogen Groups
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Question 47
Incorrect
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The causative organism for an infection in a patient you are reviewing is a facultative anaerobe.
Which of these is a facultative anaerobic organism?Your Answer:
Correct Answer: Staphylococcus aureus
Explanation:Facultative anaerobic bacteria make energy in the form of ATP by aerobic respiration in an oxygen rich environment and can switch to fermentation in an oxygen poor environment.
Examples of facultative anaerobes are:
Staphylococcus spp.
Listeria spp.
Streptococcus spp.
Escherichia coliMycobacterium tuberculosis, and Pseudomonas aeruginosa are obligate aerobe. They require oxygen to grow
Campylobacter jejuni and Clostridium spp are obligate anaerobes.
They live and grow in the absence of oxygen. -
This question is part of the following fields:
- Microbiology
- Principles Of Microbiology
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Question 48
Incorrect
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Regarding hepatitis A, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Anti-HAV IgM antibodies are diagnostic.
Explanation:Anti-HAV IgM antibodies are diagnostic. Disease in children is more commonly asymptomatic, risk of symptomatic disease increases with age. Transmission is by the faecal-oral route. Faecal shedding has been demonstrated for 2 – 3 weeks before and about a week after, the onset of jaundice. Infection confers lifelong immunity.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 49
Incorrect
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Cryptococcus neoformans is primarily transmitted by which of the following routes:
Your Answer:
Correct Answer: Inhalation of spores
Explanation:Cryptococcus neoformans is found in bird droppings and transmission is by inhalation of spores, thus the lung is the primary site of infection.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 50
Incorrect
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An elderly man with chronic heart and lung disease develops Legionnaires' disease. Which of the following clinical features is NOT typical of Legionnaires' disease:
Your Answer:
Correct Answer: Confusion
Explanation:Legionella pneumophilais a Gram negative bacterium that is found in natural water supplies and in the soil, transmitted predominantly via inhalation of aerosols generated from contaminated water (direct person-to-person spread of infected patients does not occur). It is the cause of Legionnaires’ disease. Outbreaks of Legionnaires’ disease have been linked to poorly maintained air conditioning systems, whirlpool spas and hot tubs.
The clinical features of the pneumonic form of Legionnaires’ disease include:
Mild flu-like prodrome for 1-3 days
Cough (usually non-productive and occurs in approximately 90%)
Pleuritic chest pain
Haemoptysis
Headache
Nausea, vomiting and diarrhoea
AnorexiaLegionella pneumophilainfections can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used.
The syndrome of inappropriate antidiuretic hormone secretion (SIADH) can occur with Legionnaires’ disease and will result in hyponatraemia as is seen in this case.
Legionella pneumophilainfections are resistant to amoxicillin but can be successfully treated with macrolide antibiotics, such as erythromycin, or quinolones, such as ciprofloxacin. Tetracyclines, such as doxycycline, can also be used. The majority of cases of Legionnaires’ disease are caused by Legionella pneumophila, however many other species of Legionella have been identified.
Legionella longbeachae is another less commonly encountered species that has also been implicated in outbreaks. It is predominantly found in soil and potting compost, and has caused outbreaks of Pontiac fever, the non-respiratory and less severe variant of Legionnaires’ disease. -
This question is part of the following fields:
- Microbiology
- Pathogens
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SESSION STATS - PERFORMANCE PER SPECIALTY
