Microbiology Nuts & Bolts Test Yourself - Fever in a Returned Traveller

1. Microbiology Nuts & BoltsTest Yourself - Fever in a Returned Traveller Begin here

2. The patient in this test yourself case is entirely fictitious, however it is based on many clinical scenarios the author has come in to contact with during his medical career. Any similarity to a real case is entirely coincidental.

3. Carl 36 year old computer analyst Recently returned from a business trip to North and Central America Admitted to hospital with a high fever and wide spread lymphadenopathy

4. What will be the most important part of his history of presenting complaint? What vaccinations has he received? Did he take malaria prophylaxis? Where has he been and what has he done? Has he had any insect bites? Choose A, B, C or D for the answer you feel best fits the question A B C D

5. Correct • Answer: where has he been and what has he done? • All of the questions are relevant but the most important aspect of the history of presenting complaint from a traveller with a fever is where have they been and what have they done? • Where have they been needs to be specific, not just what countries have they been to • Other aspects of their travel to include are: were they in urban or rural areas? How long where they away? When did they become unwell? • A differential diagnosis should be formulated from the patients detailed travel history

6. Carl Specifically Carl had been to Houston in Texas for 1 week, with a trip caving in the Mississippi basin, then he transferred to Kingston in Jamaica for a further 2 weeks with day trips to explore the island and it’s rural areas He did not take Malaria prophylaxis He has received all of his childhood vaccinations as well as Typhoid vaccine He was bitten by mosquitos whilst away He became unwell 3 days before returning home from Jamaica

7. What antibiotics should Carl be started on? IV Ceftriaxone PO Ciprofloxacin PO Doxycycline No antibiotics are indicated at this stage Choose A, B, C or D for the answer you feel best fits the question A B C D

8. Correct • Answer: no antibiotics are indicated at this stage • Unless the patient is septic then it is inappropriate to rush in with antibiotics as these make it harder to make a diagnosis • Antibiotics stop bacteria growing and therefore all cultures should e taken off antibiotics if it is safe to do so

9. If Carl was septic what would be the correct choice of antibiotic(s)? IV Ceftriaxone IV Ceftriaxone PLUS IV Gentamicin PO Ciprofloxacin IV Vancomycin PLUS IV Gentamicin Choose A, B, C or D for the answer you feel best fits the question A B C D

10. Correct • Answer: IV Ceftriaxone PLUS IV Gentamicin • This combination provides first line cover for possible enteric fever as well as sepsis caused by the common causes of sepsis that can occur in any patient whether they have travelled or not e.g. UTI, pneumonia, cellulitis • If there is an obvious focus of infection then it is important to make sure that is treated as well e.g. if the patient had severe abdominal pain then it would be appropriate to add IV Metronidazole to the above combination to make sure anaerobes where covered as well.

11. Carl A differential diagnosis was formulated, which in addition to normal UK causes of infection, included the following “tropical” diseases: Malaria Enteric fever Human Immunodeficiency Virus (HIV) infection Dengue Chikungunya Lyme disease Rocky mountain spotted fever West Nile fever

12. How many malaria tests must be negative for malaria tobe excluded? 1 2 3 4 Choose A, B, C or D for the answer you feel best fits the question A B C D

13. Correct • Answer: 3 • To exclude malaria 3 screens sent on separate days should be tested negative whilst the patient is off any prophylaxis they were taking • If prophylaxis is stopped in order to investigate for malaria it should restarted when the third test is negative

14. What samples should be sent to investigate for enteric fever? Blood cultures Blood cultures and stool Stool Blood cultures, stool and serum Choose A, B, C or D for the answer you feel best fits the question A B C D

15. Correct • Answer: blood cultures and stool • Enteric fever is a potentially life-threatening infection caused by the bacteria Salmonella typhi and Salmonella paratyphi • The bacteria are acquired by the faecal oral route and patients develop a gastrointestinal infection as well as sepsis • All samples for culture from a patient with possible enteric fever should be labeled HIGH RISK as these bacteria can cause laboratory acquired infections in biomedical scientists who handle pure cultures of them

16. Carl • Three malaria tests are negative • Blood cultures and stool are negative at 48 hours • Dengue, Chikungunya, Lyme and West Nile serology are negative • Epstein Barr Virus serology IgM negative, IgG positive

17. How should the EBV serology be interpreted? False positive False negative Acute glandular fever Evidence of past infection Choose A, B, C or D for the answer you feel best fits the question A B C D

18. Correct • Answer: Evidence of past infection • IgM is the first antibody produced in response to infection • Later in the course of the infection the body stops producing IgM and starts producing more efficient and specific IgG (seroconverting from IgM to IgG) • IgG in the absence of IgM suggests past exposure to infection (although if this were a vaccine preventable disease then it could also suggest previous vaccination)

19. Carl • The HIV test is positive and this is confirmed with a second sample

20. How soon after exposure does an HIV test become positive? 1 week 3 weeks 1 month 3 months Choose A, B, C or D for the answer you feel best fits the question A B C D

21. Correct • Answer: 3 months • Patients can develop a positive HIV test within a month of exposure but it can take up to 3 months • The HIV test is principally an antibody test therefore the patient has to have had time to produce antibody to the virus which can take up to 3 months • All antibody tests have periods during which they remain negative after exposure at it is important to bear these in mind when interpreting negative results • IgM tests are positive before IgG tests and indicate recent exposure to the microorganism

22. Carl • A day after the diagnosis of HIV Carl starts to become short of breath • He has a chest x-ray

23. Chest X-ray

24. What is the likely diagnosis? Histoplasmosis Tuberculosis Drug reaction PCP Choose A, B, C or D for the answer you feel best fits the question A B C D

25. Correct • Answer: Histoplasmosis • Histoplasmosis is an infection caused by the dimorphic fungus Histoplasma capsulatum • The chest x-ray shows multiple calcified nodules throughout both lung fields but worse on the right • The most common infection with Histoplasma capsulatum is an acute respiratory infection, although it can be asymptomatic or cause acute disseminated or chronic infections • The microorganism is acquired from inhaling soil or dust contaminated with bird or bat droppings • Histoplasmosis occurs in both the Mississippi basin and Jamaica but it is most likely that Carl acquired it whilst caving, so whilst it is uncommon to see it in the UK it is a good example of why a detailed travel history is important

26. Carl • Carl was started on IV Amphotericin B, the treatment of choice for Histoplasmosis in HIV infected patients • His shortness of breath slowly resolves

27. What test will inform Carl’s ongoing antimicrobial prophylaxis? Full blood count CD8 count Immunoglobulin levels CD4 count Choose A, B, C or D for the answer you feel best fits the question A B C D

28. Correct • Answer: CD4 count • In HIV infection the decision to start antimicrobial prophylaxis is related to the risk of developing or reactivating infections • This is usually related to the number of CD4 white blood cells the patient has • The normal threshold for starting prophylaxis against PCP with Co-trimoxazole (Septrin) is a CD4 count <200/mm3

29. Carl • Carl’s CD4 count was 50/mm3 • He was started on Highly Active Anti-Retroviral Therapy (HAART) as well as PCP prophylaxis

30. In addition to the normal prophylaxis which antimicrobial should be started? Itraconazole Posaconazole Ciprofloxacin Ganciclovir Choose A, B, C or D for the answer you feel best fits the question A B C D

31. Correct • Answer: Itraconazole • Patients who have had Histoplasmosis and have HIV are every likely to reactivate their histoplasmosis when they stop treatment • These patients should be starting on long term Itraconazole to prevent reactivation, usually for the rest of their lives • It is crucial to get expert advice in the management of rare or complicated infections from infectious diseases physicians or microbiologists

32. Carl • Carl improved on treatment for both his HIV and histoplasmosis and was eventually discharged home • His partner tested negative for HIV…? The End

33. Incorrect please try again Return to previous slide