Microbiology Questions

1. Gram stain of centrifuged deposit of CSF from a 15 yr old girl with acute meningitis (Gram positive cocci in chains)

   1. what treatment would you prescribe?

   2. Which virtually diagnostic clinical sign would make you suspect infection with this organism

   3. what other specimens would be useful in isolating the cause of the organism such a patient?

   4. what are the normals in CSF from healthy individuals?

2. Young woman presented at Marlborough clinic complaining of vaginal discharge. Endocervical swab taken and Gram stain shown (N. gonnorrheae)

   1. what is diagnosis?

   2. what treatment?

   3. what other types of infection may this organism cause?

   4. Name two other organisms that could have been responsible for a vaginal discharge in this patient

3. A young woman presented at the Marlborough clinic complaining of vaginal discharge. HVS taken, culture plate and Gram stain shown (Candida)

   1. What is  diagnosis

   2. what treatment would you prescribe

   3. in what circumstances might this organism cause a systemic infection

   4. name two other micro organisms that could have been responsible for a vaginal discharge in this patient?

4. 30 year old woman, regular partner, recurrent vaginal discharge - 6 months. Various GP treatments. Discharge thin and offensive, some itching, superficial dyspareunia. On examination discharge is thin, brown, offensive. Slight vulvitis, marked vaginitis, cervix normal. PV exam normal. pH = 6.5

   1. what investigations and why?

   2. what do you expect on microscopy?

   3. what treatments from GP?

   4. what treatment?

5. 40 year old woman, recent chest infection - amoxycillin. 2 week hx of vuvlal itching, burning, dyspareunia. Thick white discharge, no abdo pain.
   On examination - thick white, curdy discharge, swollen reddened vulva, normal VE

   1. What is diagnosis?

   2. What other examination unrelated to discharge?

   3. What treatment?

   4. Huband has balanitis for several months. What advice in relation to husband? What about possibility of recurrence?

6. 25 year old woman with vaginal discharge for 2/52, creamy, not particularly offensive, no itching but has dysuria and frequency.
   past 2/3 days - bilateral lower abdo pain, LMP 2 weeks ago. Regular partner for 3 years, 3 other partners in last 3 months - last 3 weeks ago. Never uses condoms with regular partners but sometimes with randoms

   1. what expect on examination?

   2. what diagnoses to consider?

   3. What treatment if any and why?

   4. what other issues would you explore with her?

7. 6 year old after eating take-away food, 3 days later presented with diarrhoea and fever. Gram stain and culture of stool (Gram -ve rods)

   1. what is infecting organism

   2. would you advise antibiotics?

      • if so what would be your first choice?

   3.  Name three types of bacteria that can cause diarrhoea through their toxins

   4. the following antibiotics can be used in the treatment of salmonella systemic infection (true/false)

      • Chloramphenical

      • Ampicillin

      • Trimethoprim

      • Vancomycin

      • Rifampicin

      • Ciprofloxacin

8. Man complained of stomach cramps and several episodes of vomiting over a period of 12 hours. Symptoms started 3-4 hours after eating a chinese takeawya meal. An aerobic culture of a sample of rice from the meal is shown and a Gram stain (Gram -ve) No growth anaerobically

   1. Patients symptoms consistent with staphylococcal food poisoning? (True/false)

   2. Bacteria isolated from rice are ubiquitous and may be found as contaminants in laboratory?

   3. Name bacterial species most commonly associated with food poisoning in UK

   4. Food poisoning following eating shellfish is most likely caused by Clostridium perfringens?

9. Photograph of Clostridium tetani stained with malachite green and safranin

   1. what distinguishing feature does it show?

   2. What is the natural habitat of C. tetani?

   3. What, if any, is the place of tetanus anti-toxin in the prophylaxis of tetanus?

   4. What other specific prophylaxis is available for tetanus?

10. Vial of PPD (tuberculin)

    1. describe briefly how you would use it?

    2. When would you need the result?

    3. What is the meaning of a positive result?

    4. What is the mechanism of a positive result?

11. This is an Elek plate used in the identification of Corynebacterium diphtheriae

    1. what is incorporated into the filter papaer strip?

    2. What can you say about the test strain in this case?

    3. How would you treat an ill child from whom such a strain is isolated?

    4. In what parts of the body might you find non-pathogenic Corynebacterium species ("diphtheroids") as part of the normal flora?

12. Immnocompromised 46 year old of 66kg on ITU,
    - Pseudomaonas aeruginosa septicaemia,
    -Urine output 380 ml/24 hours
    - gentamicin 120 mg TDS
     - pre-dose levels of gentamicin-5.2 µg/ml, post dose levels -15.4µg/ml
    -random (what?) = bacteriostatic
    - minimum inhibitory concentration of gentamicin = 0.3µg/ml, MBC 0.7µg.ml

    1. comment on these serum concentrations

    2. what advice would you give to the clinician?

    3. what does MBC mean

    4. which bacterial genera are naturally resistant to gentamicin?

13. Patient returned from 3 weeks in Sri Lanka with malaise, muscle pains, shivering and complaining of constipation. Following day temp was 40°C and he was admitted to hospital. Cultures of faeces yielded no pathogens but blood cultures yielded organism on culture plate, which was further identified with the Gram stain

    1. You would expect the identification of the organism to confirm that the patient was suffering from (True / False)
       • cholera
       • campylobacter
       • enteric fever
    2. True / False
       • antibiotic treatment wouldn't be of value in this patient?
       • enteric fever is classically spread by sewage contamination of drinking water?
       • stool cultures in enteric fever are likely to be positive within the first week of this disease?
       • treatment of enteric fever is one of the few indications for the use of chloramphenicol?
    3. The organism causing enteric fever may be carried for many years after recovery from infection. What is the most common site of carriage?
    4. How are the different strains of S. typhi recognised for epidemiological purposes?
14. Girl of 16 admitted. Hb on admission was 13 g/dl and she dropped to 7.5 g/dl 6 hrs later. There was a thin, foul smelling vaginal discharge from hich the anaerobic culture plate was grown. There was no growth on the aerobic plates. The organims is shown in this Gram stain(Gram +ve)
    1. the girl is infected with
    2. organisms of the same genus as on the culture plate can cause
       • gas gangrene ?
       • botulism ?
       • anthrax ?
    3. True/false
       1. the causative organism is a commensal in the lumen of the large bowel?
       2. specific exotoxins are responsible for the variety of manifestations of this infection
       3. the patients fall in haemoglobin was a result of an exotoxin
       4. physical inteerference is rarely necessary in this disease?
       5. antibiotic prophylaxis against this organism should be given before certain orhopaedic operations
15. The staphylococcus aureus on the antibiotic sensitivity plate was isolated from blood cultures of a main-lining drug addict. You suspect that he may have infective endocarditis
    1. which heart valve would you expect to be affected?
    2. Apart from the blood cultures what other pathology tests would help in substantiating the diagnosis if it is clinically doubtful?
    3. referring to the sensitivity plate (but not neccessarily selecting only these drugs) what antibiotic treatment would you prescribe, including approximate dose and duration?
    4. what influences your choice?
16. Study the request form and culture
    cough for 6 months, some loss of weight, recently arrived from SE asia, no chemotherapy, mucupurulent sputum sample
    1. what does the blood agar plate show (nothing)
    2. how would you further examine the sputum microscopically?
    3. what other microbiological investigations would you request on this patient?
    4. What other clinical investigations might be helpful?
    5. What specific recommendation might be neccessary for nursing such a patient in hospital?
17. Laparotomy 7 days ago. Pyrexia, cough, given amoxicillin,
    sample of sputum - amoxycillin resistant, cefuroxime sensitive, Klebsiella species +++
    1. is this culture of Klebsiella species likely to be of clinical relevance?
    2. what clinical observations would help you as the House Officer in charge in assessing the significance?
    3. What further treatmen, if any would you prescribe?
    4. Which organisms are commonly associated with acute exacerbations of chronic bronchitis?