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Flashcards in Microbiology Deck (44)
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1

List 4 ways in which an STI might present in a woman

Any 4 from: vaginal discharge(+/- urethral, rectal), ulceration (painless/painful), itching, soreness, rashes, lumps/growths, abnormal bleeding (intermenstrual bleeding/post-coital bleeding), abdominal pain, lower back pain, dyspareunia, dysuria, anorectal symptoms, systemic symptoms of infection.

2

Which of the following statements about chlamydia is true?
(a) Untreated chlamydia leads to PID in 90% of cases
(b) Chlamydia decreases the risk of ectopic pregnancy in women
(c) In terms of the bacteriology there are infectious “elementary bodies” which are extracellular and metabolically active
(d) Chylamydiae are potent inhibitors of inflammation
(e) Nucleic acid amplification tests (NAATs) are now gold standard for diagnosing chlamydia

(e) Nucleic acid amplification tests (NAATs) are now gold standard for diagnosing chlamydia

Untreated chlamydia leads to PID in 30% of cases not 90% (a). Chlamydia increases the risk of ectopic pregancy by nearly 10x, not decrease like (b). The bacteriology of Chlamydiae is that they are infectious elementary bodies that are extracellular and metabolically inactive, not metabolically active like (c); once they move into the cell they form reticulate particles which are metabolically active. They are also potent inducers of inflammation, not inhibitors(d). NAATs are now the gold standard for diagnosis, replacing the old gold standard of tissue culture, making (e) the correct answer.

3

Which of the following statements about lymphogranuloma venereum(LVG) is correct?

(a) LVG is caused by chlamydia trachomatis serovars A, B and C
(b) LVG is an invasive form of chlamydia, it passes through the epithelial cells and infects distal lymph nodes.
(c) LVG is a tropical STI and is only seen in the developing world
(d) The primary stage of classic early LGV can see a painless, non indurated genital ulcer and accompanying symptoms such as balanitis, proctitis and cervicitis.
(e) LVG can not be diagnosed the same way that other serovars of chlamydia can, it requires a specific test involving testing the serum for LVG antibodies.


(d) The primary stage of classic early LGV can see a painless, non indurated genital ulcer and accompanying symptoms such as balanitis, proctitis and cervicitis.

LVG is caused by Chlamydia trachomatis serovars L1,L2 and L3, not A,B,C, (a) which instead cause the trachoma infection. LVG is an invasive form of chlamydia, it passes through epithelial cells to infect regional lymph nodes, not distal ones (b). LVG is a tropical STI and has highest prevalence in the developing world, however in the last 5 years an ongoing outbreak has been identified in european MSM, therefore (c) is outdated. In the primary stage of classic early LGV you can get a painless, non-indurated genital ulcer and accompanying symptoms such as balanitis, proctitis and cervicitis so (d) is correct. LVG can be diagnosed the same way other chlamydiae can, with normal PCR testing, and for specific ones if LVG is suspected, so (e) is wrong.

4

Gonorrhoea can be asymptomatic in many women. True or false?

True. Women can sometimes experience discharge, but it is asymptomatic in many.

5

What is the causative organism in gonorrhoea, including gram status and type (e.g gram positive rods)

The causative organism is Neisseria Gonorrhoeae, which is a gram negative diplococci.

6

NICE states that the treatment for confirmed or suspected uncomplicated anogenital gonorrhoea is:

(a) Amoxicillin 500mg IM as a single dose, plus ceftriaxone 1g orally as a single dose.
(b) Ceftriaxone 500mg IM as a single dose, plus azithromycin 1g orally as a single dose.
(c) Ceftriaxone 500mg IM as a weekly dose for 2 weeks, plus azithromycin 500mg oral BD for 7 days
(d) Ceftriaxone 500mg IM as a single dose, plus amoxicillin 500mg oral BD for 7 days
(e) Benzylpenicillin 1g IM as a single dose, plus ceftriaxone 500mg oral BD for 7 days

From NICE guidelines: Ceftriaxone 500 mg intramuscular (IM) injection as a single dose, plus azithromycin 1 g orally as a single dose(b).If an IM injection is contraindicated or refused, offer cefixime 400 mg orally as a single dose, plus azithromycin 1 g orally as a single dose.If cephalosporins are contraindicated (for example the person has a true allergy to penicillin-type antibiotics), consider a fluoroquinolone (ciprofloxacin 500 mg, single oral dose or ofloxacin 400 mg, single oral dose) plus azithromycin 1 g, single oral dose.Only prescribe a fluoroquinolone if the infection is known to be sensitive to fluoroquinolones.

7

With regards to HPV, select the correct option.

(a) Serotypes 6 and 11 cause cervical and anal dysplasia and cancer and serotypes 16 and 18 cause genital warts.
(b) Serotypes 8 and 13 cause genital warts and serotypes 18 and 19 cause cervical and anal dysplasia and cancer.
(c) Serotypes 6 and 11 cause genital warts and serotypes 16 and 18 cause cervical and anal dysplasia and cancer.
(d) Serotypes 6 and 13 cause genital warts and serotypes 11 and 18 cause cervical and anal dysplasia and cancer.
(e) Serotypes 8 and 16 cause genital warts and serotypes 11 and 14 cause cervical and anal dysplasia and cancer.

The correct answer is (c) Serotypes 6 and 11 cause genital warts and serotypes 16 and 18 cause cervical and anal dysplasia and cancer.

8

What manifestation of disease in an adult infected with Molluscum Contagiosum is highly suspicious of that patient also having HIV?

Facial Molluscum. Facial lesions in adults are highly suspicious of HIV infection. The rule is facial molluscum in an adult is HIV until proven otherwise.

9

A 24 year old female presents to GUM clinic. She is complaining of vaginal discharge that has an offensive smell. She says she has had a similar episode before but after taking a pill it cleared up. She is sexually active with a regular partner of more than 6 months. What is the most likely diagnosis and how would you treat it?

Most likely diagnosis is bacterial vaginosis, which you would treat with oral metronidazole, 400mg BD for 5-7 days. BV is diagnosed on microscopy of gram stain of discharge, raised pH, whiff test. It is often recurrent and associated with preterm delivery.

10

A 70 year old man has been brought in to his GP by his wife because he lost sight in his right eye this morning. On further questioning she reveals that he's had episodes of dizziness, headaches and has been fatigued for the last month. He's also lost some weight, and become extremely forgetful in the past week and a half, forgetting at times who his wife of 40 years is, and where he lives. As the patient sits during the consultation his legs and arms jerk violently and on neurological examination there is bilateral hypotonia and a loss of power in the legs and arms; and the patient is blind in his right eye. Opthalmoscopy is normal.

What is the most likely cause for this man's blindness and neurological signs?

This is a classic presentation of sporadic Creutzfeldt–Jakob disease. Sporadic CJD presents with rapid dementia alongside myoclonus, cortical blindness, akinetic mutism and LMN signs. The mean age of onset is 65 years (range 45-75 years). Incidence is 1/million/year (poor bloke) and prognosis is poor with death usually occurring within 6 months.

The cause is uncertain, three possible mechanisms are somatic PRNP (which is the human prion protein gene) mutation, spontaneous conversion of PrPc to PrPsc (soluble protein to an insoluble version which causes all the problems) or possibly environmental exposure to prions.

Diagnosis of sporadic CJD is done by EEG, MRI, CSF and brain biopsy.

11

Which of the following statements is true?

(a) Tonsillar biopsy is incredibly sensitive and specific in diagnosis of Sporadic CJD.
(b) Variant CJD has an older average age of onset than Sporadic CJD.
(c) Classically in variant CJD you have neurological signs which are then followed by psychological signs.
(d) Genetic causes of CJD are more common than sporadic or acquired.
(e) Gerstmann-Straussler-Scheinker syndrome (GSS) is a characterised by a slowly progressive ataxia.

(e) Gerstmann-Straussler-Scheinker syndrome (GSS) is a characterised by a slowly progressive ataxia.

Tonsillar biopsy is incredibly sensitive and specific in diagnosis of variant CJD not sporadic CJD as in (a). Variant CJD has a younger average of onset (26) than sporadic CJD (65). Classically in variant CJD you have psychiatric signs such as dysphoria, anxiety, paranoia and hallucinations, which are then followed by neurological signs such as peripheral sensory symptoms, ataxia, myoclonus, chorea and dementia, therefore (c) is incorrect as it's the other way round. Genetic causes of CJD account for around 15% of cases, acquired 5% and sporadic CJD responsible for 80% of cases, therefore (d) is wrong. Gerstmann-Straussler-Scheinker syndrome (GSS) is a characterised by a slowly progressive ataxia so (e) is correct. GSS also causes diminished reflexes and dementia and has an onset age of 30-70 years and a survival of 2-10 years.

12

List all the parts of CURB65 acronym and how this is used in the management of pneumonia patients.

C - Confusion (AMTS <8)
U - Urea > 7mmol/L
R - Respiratory rate >30/min
B - Blood pressure is hypotensive (Less than 90/60)
65 - >65 years of age.

All of these factors are associated with increased mortality, and help form a framework for management of pneumonia patients, with each element awarding 1 point:
0-1: Treat as an outpatient
2: Consider a short stay in hospital or watch very closely as an outpatient
3-5: Requires hospitalization with consideration as to whether they need to be in the intensive care unit

13

A 68 year old unkempt gentleman comes in to A&E. He reports feeling suddenly short of breath and feeling feverish. He's got a productive cough with dirty, brown sputum. He's also got stabbing pains in his chest when coughing, feels generally unwell and has vomited twice. On examination he is tachycardic and tachypnoeic, and has some dullness to percussion and crepitations on auscultation of his right lung.

What is the most likely causative organism?
(a) Neisseria Meningitidis
(b) Mycoplasma Pneumoniae
(c) Streptococcus Pneumoniae
(d) Influenza A
(e) Rotavirus
(f) Klebsiella pneumoniae
(g) Varicella Zoster
(h) Salmonella Enterica
(i) Legionella Pneumophila
(j) Mycobacterium Tuberculosis

The most likely causative organism is (c), Streptococcus Pneumoniae.

The epidemiology is that it's prevalent and dangerous. The elderly, children and patients with underlying illnesses (HIV, alcoholism) are particularly at risk.

Strep pneumo can also case URTIs/exacerbation of COPD, meningitis and RARELY endocarditis/cellulitis.

Management of the patient would be to admit (CURB65 score of 2 on the details given in the question) and the antibiotic of choice would be Amoxicillin.

14

23 year old army cadet presents to GP with a 2 week history of headache, malaise and non-productive cough. Examination of the chest is unremarkable, and early blood tests show normal inflammatory markers.

What is the most likely causative organism?
(a) Neisseria Meningitidis
(b) Mycoplasma Pneumoniae
(c) Streptococcus Pneumoniae
(d) Influenza A
(e) Rotavirus
(f) Klebsiella pneumoniae
(g) Varicella Zoster
(h) Salmonella Enterica
(i) Legionella Pneumophila
(j) Mycobacterium Tuberculosis

The most likely causative organism is (b) Mycoplasma Pneumoniae.

Classically causes outbreaks in institutions and military barracks due to the droplet spread. Examination findings may be minimal compared to radiological. WCC usually normal. Diagnosis is done on serology. Extrapulmonary complications can be CNS involvement, Stevens-Johnson, AIHA.

Management of this patient would be in the community, with a macrolide such as erythromycin.

15

You're an F1 working in A&E during a heatwave when over the course of 6 hours, 4 cardiologists come in, all presenting with confusion, fever, headache, myalgia, abdominal pain and diarrhoea. Their initial blood tests come back and they all have hyponatraemia and deranged LFTs.

What is the most likely causative organism?
(a) Neisseria Meningitidis
(b) Mycoplasma Pneumoniae
(c) Streptococcus Pneumoniae
(d) Influenza A
(e) Rotavirus
(f) Klebsiella pneumoniae
(g) Varicella Zoster
(h) Salmonella Enterica
(i) Legionella Pneumophila
(j) Mycobacterium Tuberculosis

The most likely causative organism would be (i), Legionella Pneumophila.

This is a classical presentation of Legionnaires disease. The four cardiologists had been at a convention and due to the heatwave(cheeky detail) the air conditioning had been on. This organism colonises water piping systems including air conditioning. Infection is acquired by inhalation, human to human transmission does not occur.

Treatment in severe cases would be IV erythromycin +/- rifampicin. Treatment of less severe cases would be an oral macrolide like clarithromycin or erythromycin.

16

21 year old 28+4 week pregnant G1P0 lady presents to her GP with a 5 day history of a flu-like illness with coryzal symptoms, fever and myalgia. She also has SOB and a cough, and on examination she is hypoxic, tachycardic and has crackles on auscultation.

What is the most likely causative organism?
(a) Neisseria Meningitidis
(b) Mycoplasma Pneumoniae
(c) Streptococcus Pneumoniae
(d) Influenza A
(e) Rotavirus
(f) Klebsiella pneumoniae
(g) Varicella Zoster
(h) Salmonella Enterica
(i) Legionella Pneumophila
(j) Mycobacterium Tuberculosis

The most likely causative organism is (d) influenza A.

Under normal circumstances uncommon in adults but a viral URTI commonly precedes bacterial pneumonia.

Risk factors for a viral pneumonia include: pregnancy, immunocompromised, pre-existing cardiopulmonary disease and smoking.

Organisms are influenza A in the vast majority of cases, others include CMV, EBV and VZV which can be life threatening.

Treatment is supportive, however antivirals can be used in serious cases such as oseltamivir which is a neuraminidase inhibitor.

17

List three common sites of Extra-pulmonary TB

Any three from Lymphadenitis, Brain (TB meningitis or cerebral tuberculoma), Bone (spinal TB - paraspinal abcess, osteomyelitis, discitis), Pericarditis, abdominal (peritonitis, ileitis), genito-urinary (renal, testicular) and misc (skin, liver etc)

18

Name the four drugs used in treatment of classical TB, as well as the classic dosage lengths.

Rifampicin, Isoniazid, Pyrazinamide and ethambutol. 4 for 2 months then 2 (Rifampicin and Isoniazid) for 4 months. Pyridoxine is given alongside Isoniazid to counteract its side effects.

19

Which of the following is the gold standard diagnosis test for Tuberculosis?
(a) History and clinical findings
(b) Chest X-ray
(c) Skin tests (Mantoux/Heaf)
(d) Sputum microcopy
(e) Sputum culture

Sputum culture is the gold standard for diagnosis of TB. The culture is extremely slow-growing and can take 3 weeks or more. You need to take three cultures and grow them to have a diagnosis.

20

The Influenza virus infection causes respiratory disease because:-

(a) The host cell receptor the virus binds to is only expressed in the lung
(b) The influenza virus can only get into the body through the mouth.
(c) The influenza virus requires activation by host cell proteases that are only expressed in the respiratory tract
(d) The influenza virus envelop can only fuse with membranes of cells that secret mucus.

The correct answer is (c) The influenza virus requires activation by host cell proteases that are only expressed in the respiratory tract.

Influenza Haemagglutinase (HA) requires cleavage to allow for the activation of the virus; cleavage is done by proteases (i.e. Clara tryptase) which cleave at a specific site. These proteases are present in the respiratory tract and so only here can HA be produced that is in a transmittable form.

21

The influenza vaccine given to those at greater risk of complications of flu in the UK is :-

(a) A live, attenuated virus
(b) A purified fraction containing haemagglutinase and neuraminidase of an inactivated virus
(c) A purified haemagglutinase protein, expressed in insect cells.
(d) An immunoglobulin fraction from sera of immune patients.

The correct answer is (b) A purified fraction containing haemagglutinase and neuraminidase of an inactivated virus.

The vaccine used is a trivalent vaccine. Each injected seasonal influenza vaccine contains three influenza viruses:
-one influenza type A subtype H3N2 virus strain
-one influenza type A subtype H1N1 (seasonal) virus strain
-one influenza type B virus strain

22

Which of the following statements is false?

(a) Augmentin is made by the addition of clavulanic acid to amoxicillin.
(b) Penicillins cannot cross the intact blood-brain-barrier.
(c) Glycopeptides (such as Vancomycin) are large molecules unable to penetrate gram negative bacteria's outer cell wall, but are active against gram positive organisms.
(d) Glycopeptides are hepatoxic so it's important to monitor liver enzymes to screen for liver damage.
(e) It is important to never prescribe tetracylines to children or pregnant women.

The false statement is (d) Glycopeptides are hepatoxic so it's important to monitor liver enzymes to screen for liver damage.

Glycopeptides are nephrotoxic, not hepatoxic, so it's important to monitor drug levels to prevent accumulation.

23

Match the conditions with the appropriate antibiotics for each case

Flucloxacillin
Amoxicillin
Vancomycin
Trimethoprim
Ceftriaxone

Bacterial Meningitis
Community acquired UTI
HAI of MRSA
Community acquired Pneumonia
Impetigo

Flucloxacillin is used to treat skin infections such as impetigo, cellulitis and wound infections as the common organisms are staph aureus and beta-haemolytic strep.

Amoxicillin is used to treat mild community acquired pneumonia. If severe consider cefuroxime and clarithromycin.

Vancomycin is first line treatment for hospital acquired MRSA.

Trimethoprim is the treatment of choice for simple cystitis UTI in the community. If it was a hospital acquired UTI (most common type of HAI) then treat with cephalexin or augmentin.

Ceftriaxone is used to treat Bacterial Meningitis.

24

Which of the following is not a symptom of congenital varicella syndrome?

(a) Skin scarring
(b) Limb hypoplasia
(c) Cortical atrophy
(d) Psychomotor excitation
(e) Choreoretinitis

(d) Psychomotor excitation is not a symptom of congenital varicella syndrome, instead it's psychomotor retardation.

Varicella syndrome is a complication of a varicella infection of the pregnant mother in early pregnancy, especially between 12-20 weeks gestation.

25

What is the commonest cause of viral congenital infection in the UK?

Congenital CMV infection.

Birth prevalence is 3/1000 in the UK. Roughly 13% of which will have cytomegalic inclusion disease. The other 87% are asymptomatic but around 13% of those will develop sequelae on follow up such as hearing defects and impaired intellectual performance.

The symptoms of cytomegalic inclusion disease are IUGR, jaundice, hepatosplenomegaly, chorioretinitis, thrombocytopaenia, encephalitis and occasionally microcephaly

26

Epstein-Barr virus infection in pregnancy is not associated with adverse foetal or maternal outcomes. True or false?

True! The mother may experience infectious mononucleosis symptoms as in anyone with an EBV infection but there is no additional risk to either mother or foetus.

27

State the classic triad of symptoms found in congenital rubella syndrome

The triad is sensorineural deafness (58% of patients), eye abnormalities such as retinopathy, cataracts and micropthalmia (43% of patients) and congenital heart disease, especially pulmonary artery stenosis and patent ductus arteriosus (50% of patients).

Congenital rubella syndrome occurs when the mother is infected with rubella during the first and second trimester of pregnancy. If the infection is before 8 weeks there is 20% rate of miscarriage, and if the infection is before 10 weeks gestation there is 90% incidence of foetal abnormalities. Infection after 20 weeks carries no documented risk.

28

Which of the following statements is true?

(a) Infection with measles during pregnancy carries significant risk of congenital abnormalities to the foetus.
(b) Infection with parvovirus B19 in pregnancy after 20 weeks gestation carries a 3% risk of hydrops fetalis.
(c) Coxsackie infection in pregnancy is associated with early onset neonatal hepatitis and congenital myocarditis.
(d) Infection with measles during pregnancy is not associated with miscarriage and IUD
(e) MMR and chickenpox vaccines are both inert purified protein vaccines so can be given to pregnant women

(c) Coxsakie infection in pregnancy is associated with early onset neonatal hepatitis and congenital myocarditis.

Infection with measles during pregnancy has not been shown to cause any congenital abnormalities so (a) is wrong. Conversely it does cause foetal loss through miscarriage or IUD, preterm delivery and increased maternal morbidity so (d) is also wrong.

Infection with parvovirus B19 BEFORE 20 weeks gestation carries a 3% risk of hydrops fetalis so (b) is wrong. Infection after 20 weeks has no documented risk.

Coxsakie infection in pregnancy is associated with early onset neonatal hepatitis, congenital myocarditis, early onset childhood insulin dependent diabetes mellitus and miscarriage and IUD, so (c) is right.

Both the MMR and chickpox vaccines are live vaccines so should not be given to pregnant women so (e) is wrong

29

What are the two most common causes of acute bacterial meningitis in neonates?

Escherichia coli and Group B strep are the commonest pathogens in neonates. For all other ages it's neisseria meningitidis and streptococcus pneumoniae.

30

70 year old male attends A&E with haemoptysis and a cough of 1 week duration. He lives alone and drinks to excess every day. Microscopy of the sputum reveals a gram negative rod. What is the causative organism?

(a) Streptococcus pneumoniae
(b) Klebsiella pneumonia
(c) Haemophilus influenzae
(d) Staphylococcus aureus
(e) Legionella pneumophila

The correct answer is (b) Klebsiella pneumonia.

Klebsiella is associated with alcoholism, an elderly patient and presenting with haemoptysis. On microscopy it is a gram negative rod.