Micro Flashcards
A 50 year old marine biologist was bitten by a fish three weeks ago. There is now an eruption of nodules around the bite, which has healed poorly.
The GP sends off a wound swab after discussing with a microbiologist and the swab is positive for an atypical mycobacterium.
What is the likely cultured organism?
Mycobacterium marinum
What organism is responsible for the sexually transmitted infection Chancroid, which causes multiple painful ulcers.
Haemophilus ducreyi
What disease is caused by Borrelia burgdorferi?
Lyme disease
What gram positive organism is associated with tumbling motility and rockets?
Listeria monocytogenes
What diagnostic test is used to diagnose chlamydia infection?
Nucleic Acid Amplification Tests
A 33 year old man presents to their GP with multiple elevated, small, pink lesions with a dimple in the center over his abdomen.
He denies any pain, itching or bleeding. They are not obviously infected. He has no history of cold sores and had chickenpox as a child.
What infection must be ruled out in a person presenting with this characteristic rash?
HIV
What is the first line antimicrobial for treatment of Lyme Disease?
If no medication is indicated, please type “N/A”
Doxycycline
A 72 year old man with COPD and poorly controlled HIV presents to the emergency department following a severe episode of haemoptysis. He reports no other symptoms.
A high resolution CT scan reveals multiple large bullae and a large left upper lobe rounded mass surrounded by a crescent of air.
Serum galactomannan is positive.
What is the diagnosis?
Aspergilloma
A previously well 53 year old plumber is seen in A&E after a worsening of his symptoms. He was treated in the community by his GP five days ago for a “simple chest infection”.
On examination, he appears clinically unwell, has a fever of 37.9, is tachycardic and tachypnoeic. There are crepitations in the R base. A CXR has been ordered.
What organism is likely to be responsible for his symptoms?
Legionella pneumophilia
What is the first line antibiotic for the treatment of acute otitis media in a patient with no known allergies?
Amoxicillin
What is the full scientific name of the organism responsible for Q Fever?
Coxiella burnetii
To what phylum do the organisms Leptospira spp, Borrelia spp, Treponema spp and Brachypsira spp belong?
Spirochaetes
What is the name of the neurological sign of a pupil that accommodates, but does not react to light?
Argyll Robertson pupil
What organism is responsible for the sexually transmitted infection Chancroid, which causes multiple painful ulcers.
Haemophilus ducreyi
How is Q fever typically diagnosed?
Serology
Q Fever (Coxiella Burnetii) is a disease characterised by abrupt onset of flu-like symptoms, fever, headache, muscle pain, chills which may progress (for exam purposes) to an atypical pneumonia and ARDS or endocarditis. However, most patients are asymptomatic.
Diagnosis is via serology and it is treated effectively with doxycycline or ciprofloxacin. Only one bacterium is required to cause infection.
Typically Q fever is transmitted via contaminated dust or contact with the bodily fluids of infected animals (milk, urine, feces of cows, sheep, goats)
Typically only found in people at high risk of infection e.g. vets, farmers.
A 50 year old lady of previous good health presents to her GP with multiple unsightly, discoloured, brittle toenails. Underneath each toenail is a chalky material.
The GP suspects multiple fungal nail infections. Nail scrapings grew dermatophytes and a PoC HIV ELISA is negative.
Prior to starting terbinafine, a systemic antifungal, what blood test should be ordered?
LFTs
What is the scientific name of the pork tapeworm?
Taenia solium
A 46-year-old man with poor adherence to his HIV medication presents to his GP with neck stiffness, fever and photophobia. The GP arranges for an ambulance.
In the emergency department, an LP is performed.
India ink staining of CSF gives following report: “CSF sample positive for yeast cells with a gelatinous capsule. Positive halo sign.”
What is the causative organism?
Cryptococcus neoformans
A 73 year old alcoholic is admitted to the respiratory ward from the Emergency Department due to a severe chest infection.
There are crepitations in the mid right zone and this is associated with consolidation on X ray.
On examination he is visibly drunk and his level of self care is poor. He is tachycardic and pyrexial with a fever of 38.
Sputum culture showed Gram Positive Diplococci.
What organism is responsible for his chest infection?
Streptococcus pneumoniae
A sexually active homosexual man received treatment two hours ago for genital primary syphilis.
He was given a single of dose of IM benzylpenicillin.
He presents to the emergency department reporting he has become unwell, with a fever, headache and muscle aches. He is concerned he is having an allergic reaction.
He is pyrexial at 38C and his blood pressure is 98/76.
What syndrome is he suffering from?
Jarisch Herxheimer reaction
A 25-year-old man presents for an STI check. He is sexually active with multiple female and male partners over the last year. He reports being inconsistent with use of condoms.
He reports occasional mild genital itching and sores on the penile shaft which come and go.
On examination he is circumcised with no inguinal lymphadenopathy, no visible lesions on the penile shaft and no urethral discharge.
What drug could be initiated if his symptoms recur?
Aciclovir
What is the treatment for human tapeworms in adults?
Praziquantel
Which first-line Tuberculosis medication causes visual disturbances?
Ethambutol
The standard first-line treatment regime for Mycobacterium tuberculosis lung infection is RIPE:
Rifampicin Isoniazid Pyrazinamide Ethambutol
All four antibiotics are given for 2 months. Rifampicin and Isoniazid are continued for a further 4 months.
Side effects of TB medication include:
Rifampicin: Hepatotoxicity (deranged LFTs), Drug interactions (induces cytochrome P450), Orange secretions
Isoniazid: Hepatotoxicity, Peripheral neuropathy
Pyrazinamide: Hepatotoxicity, Hyperuricaemia
Ethambutol: Optic neuritis
What disease is caused by Borrelia burgdorferi?
Lyme disease
A 73-year-old immunocompromised man presents to the Emergency Department with a 3-day history of fever, dry cough, muscle ache and severe headache. There is no sign of meningism. Respiratory and cardiovascular exam is normal.
A rapid flu swab is positive for Influenza A and RT-PCR for SARS-CoV-2 on a NP swab was negative.
What antiviral drug may be indicated for this patient?
Oseltamivir
Classically the urine of what animal transmits the spirochaete responsible for leptospirosis?
Rats
A patient is suspected to have a community acquired pneumonia. Their CURB 65 is 1. Atypical infection is not suspected.
If indicated, what is the first line antibiotic for the treatment of this patient?
(If you do not feel an antibiotic is indicated, type “N/A”)
Amoxicillin
Presence of atypical lymphoycytes on a peripheral blood film suggests what diagnosis?
Infectious Mononucleosis
A 25 year old female presents for an STI screen.
She reports feeling feverish, has diffuse lower abdominal pain and dyspareunia.
A Nucleic Acid Amplification Test (PCR) is positive for the presence of a gram negative intracellular bacterium.
What is the likely causative organism?
Chlamydia trachomatis
What is the vector of Malaria?
Female Anopheles mosquito
Malaria is an infectious tropical disease that is transmitted by the female anopheles mosquito.
It is most common in tropical regions including Africa, Asia and Latin America.
It is caused by parasites called Plasmodium. There are five different species that are known to cause malaria: P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi.
Typical signs and symptoms include fever, myalgia, lethargy, vomiting and headaches.
In severe cases, it may present with jaundice, splenomegaly, seizures and death.
Often, it presents with vague symptoms.
Investigations include thick and thin blood films to identify parasites and determine species respectively.
Rapid Diagnostic Tests can also be used to detect malaria antigens.
Treatment depends on severity.
Severe malaria is treated with IV artesunate.
What antimicrobial is first line for severe, widespread fungal nail infection in a an elderly patient with no known allergies?
Recent bloods including FBC, U&Es, LFTs and TFTs were all normal.
Terbinafine
Severe malaria is defined as parasitaemia of more than?
2%
Severe malaria presents with high parasitaemia (>2% of red blood cells), altered consciousness, respiratory distress, circulatory collapse, metabolic acidosis and organ failure.
Treatment includes IV artesunate
A 20 year old woman is seen in the sexual health clinic for offensive smelling, yellow-green discharge. This is associated with some dysuria.
What organism is likely to be responsible for her symptoms?
Trichomonas vaginalis
What viral enzyme is inhibited by oseltamivir?
Neuraminidase
What diagnostic test is used to diagnose chlamydia infection?
Nucleic Acid Amplification Tests
A child is suspected of having meningococcal septicaemia in the GP setting.
As you prescribe the medication, you note the child has a documented reaction to flucloxacillin, when they developed a mild rash.
What medication, if any, should the GP administer in the practice, before arranging immediate hospital admission?
If no medication is indicated, please type “N/A”.
Benzylpenicillin
A 34 year old Indian gentleman has grown Mycobacterium tuberculosis in a sputum sample.
He is started on the RIPE treatment regime.
He presents to his GP after 5 days and says his tears are a strange colour.
Which anti-tuberculous medication is classically associated with this side effect?
Rifampicin
The standard first-line treatment regime for Mycobacterium tuberculosis lung infection is RIPE:
Rifampicin Isoniazid Pyrazinamide Ethambutol
All four antibiotics are given for 2 months. Rifampicin and Isoniazid are continued for a further 4 months.
Side effects of TB medication include:
Rifampicin: Hepatotoxicity (deranged LFTs), Drug interactions (induces cytochrome P450), Orange secretions
Isoniazid: Hepatotoxicity, Peripheral neuropathy
Pyrazinamide: Hepatotoxicity, Hyperuricaemia
Ethambutol: Optic neuritis
A 33 year old man presents to their GP with multiple elevated, small, pink lesions with a dimple in the center over his abdomen.
He denies any pain, itching or bleeding. They are not obviously infected. He has no history of cold sores and had chickenpox as a child.
What infection must be ruled out in a person presenting with this characteristic rash?
HIV
What is the first line antimicrobial for treatment of Lyme Disease?
If no medication is indicated, please type “N/A”
Doxycycline
A patient undergoing allogeneic stem cell transplantation requires a blood transfusion.
All blood products are routinely screened for HIV.
What other virus must be screened for in the donor blood products prior to giving it to this patient?
Cytomegalovirus
A 40 year old woman presents to her GP complaining of malodorous vaginal discharge. She is sexually active with her partner only. She has no other symptoms.
The GP arranges for a pregnancy test which comes back as negative. An STI screen is negative. She is up to date with her smears and has never had an abnormal result.
What is the likely diagnosis?
Bacterial Vaginosis
During which trimester of pregnancy is the risk of HSV transmission to a neonate greatest?
Third Trimester
A 72 year old man with COPD and poorly controlled HIV presents to the emergency department following a severe episode of haemoptysis. He reports no other symptoms.
A high resolution CT scan reveals multiple large bullae and a large left upper lobe rounded mass surrounded by a crescent of air.
Serum galactomannan is positive.
What is the diagnosis?
Aspergilloma
What viral protein is responsible for the virulence and tropism of SARS-CoV-2?
Spike protein
SARS-CoV-2 is a member of the Coronaviridae family.
It is a small, single stranded RNA virus with the ability to cause Coronavirus Disease 19 (COVID-19) in humans.
Its main proteins include the S protein (required for binding to ACE2 on human cells) and the N protein - the nucleocapsid.
A previously well 53 year old plumber is seen in A&E after a worsening of his symptoms. He was treated in the community by his GP five days ago for a “simple chest infection”.
On examination, he appears clinically unwell, has a fever of 37.9, is tachycardic and tachypnoeic. There are crepitations in the R base. A CXR has been ordered.
What organism is likely to be responsible for his symptoms?
Legionella pneumophilia
What is the first line antibiotic for the treatment of acute otitis media in a patient with no known allergies?
Amoxicillin
A 55 year old gentleman is referred to gastroenterology by his GP.
He has persistent dysphagia and weight loss. He has no other past medical history.
At endoscopy a diagnosis of oesophageal candidiasis is made.
What is the next most appropriate investigation?
HIV test
Chloramphenicol acts on which part of the bacterial ribosome?
50S subunit
There are 5 main groups of antimicrobial agents that work by inhibiting bacterial protein synthesis. These can be remembered using the acronym TAMCO:
Tetracyclines (e.g. Doxycycline)
Aminoglycosides (e.g. Gentamicin)
Macrolides (e.g. Erythromycin)
Chloramphenicol
Oxazilidinediones
Aminoglycosides and Tetracyclines work by binding to the 30S subunit of ribosomes.
Macrolides and Chloramphenicol work by binding to the 50S subunit of ribosomes.
Oxazilidinediones works by binding to the 23S component of the 50S subunit of ribosomes.
A 58 year old gentleman is undergoing chemotherapy for multiple myeloma. As per safetynetting advice he has received, he presents to the Emergency Department feeling unwell. In triage, his temperature is 38.9c.
He describes a history of 2-3 days of nonspecific malaise, which he attributed to his chemotherapy last week. This morning, he awoke sweating with intermittent rigors and a severe headache. You take a full history and find that he has pain in his lower back, hip and his right knee, which has a visible, tender, effusion.
On examination, he is curled up in bed with the sheets over his head - he says he is cold.
As part of your neurological examination, you ask him to flex his hips fully, flex and then extend his knees. With difficulty, he is able to extend his left knee, but he cannot to extend his right knee due to pain.
What condition explains the patient’s symptoms?
Septic Arthritis
A patient is suspected to have a community acquired pneumonia. Their CRB 65 is 3 and they have no known allergies.
In addition to clarithromycin, what is the other first line antibiotic that should be prescribed for this patient?
Co-amoxiclav
What antibiotic should be prescribed for a penicillin allergic, clinically stable patient with cellulitis?
If no antibiotic is indicated, please type “N/A”
Clarithromycin
What antibiotic would you prescribe first line for an infective exacerbation of COPD with a suspected bacterial etiology?
Amoxicillin
A 55 year old lady presents with fever, pleuritic chest pain, shortness of breath and cough productive of rusty-coloured sputum.
What is the most likely causative organism?
Streptococcus pneumoniae
