Past papers 4 Flashcards
What is the most appropriate treatment for campylobacter
When is therapy indicated?
Indications for antimicrobial therapy include high fever, systemic infection with sustained bacteraemia, grossly bloody diarrhoea, and persistence of symptoms for >1 week.
Antibiotics should also be used in immunocompromised patients.
Antibiotics are not indicated in uncomplicated cases
Give IV if complicated cases
azithromycin or cipro
5-7 days
- How is an open reading frame stopped?
a. stop codon
b. promoter
c. transposon
d. plasmid
stop codon - signals termination of translation
An open reading frame is a portion of a DNA molecule that, when translated into amino acids, contains no stop codons.
- How is CMV best diagnosed post renal transplant?
a. DEAFF urine
b. CMV igM
c. Renal Biopsy
d. DNA CMV
e. Paired sera antibody
Renal biopsy
- A detergent instead of chlorine is used to clean up after a spillage in the lab. Which virus is least likely to be removed?
a. influenza
b. polio
c. hsv
d. hep b
e. hiv
?
- A young woman presents with pharangitis and septic shock. What is likely organism?
Fusobacterium
- Match the Vectors
Leishmania Malaria Loa loa Onchocerca lyme SA trypansomiasis African trypanosomiasis
Anopheles phlebotomus sp chrysops simulia ixodes reduvid palpalis
Leishmania - phlebotomine sandfly
Malaria - anopheles
Loa loa - chrysops
Onchocerca - simulium black fly
lyme - ixodes
SA trypansomiasis - reduviid
African trypanosomiasis - Glossinia palpalis
- Match the mechanism
linezolid aminoglycoside moxifloxacin zidovudine ritonavir
Bind 30s Bind 50s RT inhibitor protease inhibitor gyrase inhibitor
linezolid - Bind 50s
aminoglycoside - Bind 30s
moxifloxacin - DNA gyrase inhibitor
zidovudine - NRTI
ritonavir - protease inhibitor
- Match the drug complication
AML with recurrent low platelet with therapy for VRE Lipodystrophy Red face after infusion Confusion after prophylaxis for flu Becoming pregnant on the pill
Rifampicin amantadine vancomycin linezolid ostelmavir ritonavir
AML with recurrent low platelet with therapy for VRE - linezolid
Lipodystrophy - ritonavir
Red face after infusion - vancomycin
Confusion after prophylaxis for flu - amatadine
Becoming pregnant on the pill - rifampicin
- Match Symptom and disease in a HIV patient
Dry cough limb weakness blindness meningitis dysphagia
candida cryptococus cmv toxoplasmosis pcp isospora jc virus
Dry cough - PCP
limb weakness - JC/ cryptococcus/ toxo?
blindness - CMV
meningitis - cryptococcus
dysphagia - candida
- Match the mechanism
Antibody production MHC1 Ag presentation recognition APC and LN Phagocytic cell with effector molecules tissue monocytes
Macrophage NK cells PMN - polymorphonuclear leucocyte CD8 B cells plasma cells
Antibody production - plasma cells
MHC1 Ag presentation - CD8
APC and LN - B cell
Phagocytic cell with effector molecules - NK cell
Tissue monocyte - macrophage
- Match the organisms
Brazilian with earthworm
CLM in person returned from the Caribbean
Recurrent cholangitis
Diarrhoea and cholangitis
Ascaris
clonorchis
cryptosporidium
A. braziliensis
Brazilian with earthworm - Ascaris
CLM in person returned from the Caribbean - Ancylostoma braziliensis
Recurrent cholangitis - clonorchis
Diarrhoea and cholangitis - cryptosporidium
- Match the disinfectant collection
Endoscopes equipment
Floor and surface
Hands
Blood spillage in CAT 3
Heat H20 to 60, chlorhexadine, water and detergent, 1: 10000, paracetic acid, glutaraldehyde,
?
A man returns from Vietnam with cough and bibasal changes on CXR you suspect melioidosis.
What will show up on the sputum culture?
Gram neg rods
oxidase positive
- In the management of TBM, which is important with regards to crossing the BBB
a. ethambutol
b. isoniazid
c. pyrazinamide
d. streptomycin
e. cycloserine
Isoniazid has almost 100% concentration compared to blood
Pyrazinamide has very high concentrations too
Streptomycin/ ethambutol does not cross BBB
The haematology department has been putting together recommendations for patients who want to travel abroad, which vaccines would you not recommend?
Lives vaccines
live influenza vaccine (Fluenz Tetra) Measles, Mumps and Rubella vaccine (Priorix, MMRVaxPro) Rotavirus vaccine (Rotarix)* Shingles vaccine (Zostavax) BCG vaccine Oral typhoid vaccine (Ty21a) Varicella vaccine (Varilrix, Varilvax) Yellow Fever vaccine
In this question - yellow fever, typhoid,
A neonate with meningitis. Gram positive bacteria have been isolated from blood cultures.
If you can perform only one test to identify species, what would you pick?
tumbling motility - listeria
Catalase/ coagulase tests will be useful, but will not speciate
A gram negative coccus has been isolated from a patient with fever of unknown origin.
It is oxidase positive, can’t grow without blood and can ferment glucose but not maltose.
What is it likely to be?
Acinetobacter
Moraxella catarrhalis
N. meningitidis
N. gonorrhoea
Acinetobacter - oxidase negative, ferment glucose
Moraxella catharrhalis - oxidase positive, fermentation none
Neiserria meningidis - oxidase positive, ferment glucose and maltose
Neiserria gonorrhoea - oxidase positive, ferment glucose
Neisseria species are fastitidious, and can’t grow without blood. Normally use horse blood agar/ chocolate agar
A mycobacterium grows on LJ slopes at 37ºC after 4 weeks and has bright yellow colonies. Which of the following is it likely to be?
M. fortuitum M. chelonoae M. kansasii M. malmoense M. paratuberculosis
M kansasii?
Runyon classification
Which bacteria are you most likely to find extended spectrum B-lactamses? (E.coli not an option)
E. coli
Klebsiella
What is prozone effect?
Sometimes called hook effect
immunologic phenomena
In an agglutination test, a person’s serum (which contains antibodies) is added to a test tube, which contains a particular antigen.
If the antibodies agglutinate with the antigen to form immune complexes, then the test is interpreted as positive. However, if too many antibodies are present that can bind to the antigen, then the antigenic sites are coated by antibodies, and few or no antibodies directed toward the pathogen are able to bind more than one antigenic particle.
Since the antibodies do not bridge between antigens, no agglutination occurs. Because no agglutination occurs, the test is interpreted as negative. In this case, the result is a false negative. The range of relatively high antibody concentrations within which no reaction occurs is called the prozone.
Can result in false negative results
- prozone - excess antibody
- postzone - excess antigen
What would you do if a surgeon who was a non-responder to the Hep B vaccine had a needle stick injury from a patient who was Hep B positive?
Give vaccine and HBIG
If a person is repeatedly HepBsAg pos, HepBeAg pos, IgM core antibody negative and IgG core antibody negative, they are what?
HBV positive
High infectivity
Reason for not giving influenza vaccine?
Allergy to egg
Avoid live vaccine in immunocompromised. Give alternative inactivated injection
Why is CJD not classified as a virus?
Does not contain nucleic acid
How does CMV develop resistance to the following antivirals?
ganciclovir
foscarnet
cidofovir
change in pp66
mutation in UL97
mutation in UL54
UL54 - ganciclovir, foscarnet, cidofovir - DNA polymerase
UL97 - ganciclovir - impaired ganciclovir phosphorylation
What is mechanism of action of fusidic acid?
Fusidic acid inhibits protein synthesis by binding EF-G-GDP, which results in the inhibition of both peptide translocation and ribosome disassembly.
What is most common mechanism of resistance to aminoglycosides, but specifically staph aureus?
The three mechanisms of resistance to aminoglycosides are changes in the position of the ribosomal binding site for the drug, reduced permeability of the drug, and drug inactivation by enzymes.
The enzymatic inactivation by aminoglycoside-modifying enzymes (AMEs) is an important mechanism of resistance in staphylococcal species
Pt presents with endocarditis, B/c grows gram pos cocci which grow on both blood agar and MacConkey and are ampicillin resistant:
Enterococcus Faecalis
Enterococcus faecium
Strep pneumo
Strep bovis
Enterococcus faecium
Enterococcus faecalis is sensitive to penicillin
Enterococci - two species are common commensal organisms in the intestines of humans: E. faecalis (90–95%) and E. faecium (5–10%)
an important feature of this genus is the high level of intrinsic antibiotic resistance. Some enterococci are intrinsically resistant to β-lactam-based antibiotics (penicillins, cephalosporins, carbapenems), as well as many aminoglycosides.[9] In the last two decades, particularly virulent strains of Enterococcus that are resistant to vancomycin (vancomycin-resistant Enterococcus, or VRE) have emerged in nosocomial infections
Streptococci do not grow on MacConkey agar, so useful for identifying enterococci
What is definition of sterilisation?
Sterilization refers to any process that removes, kills, or deactivates bacteria/ fungi/ viruses/ prions/ protozoa
Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration
What is mechanism of action of glycopeptides?
Prevents cell wall cross-linking
Which of these is a risk factor for VRE bacteraemia?
Repeated enemas Metronidazole use Persistent diarrhoea Urinary catheterisation Inflammatory bowel disease
Identified risk factors for VRE bacteremia include:
prior intestinal colonization prior long-term antibiotic use increased severity of illness hematologic malignancy bone marrow transplant mucositis neutropenia indwelling urinary catheters corticosteroid treatment chemotherapy parenteral nutrition
4yrs old child from Kenya presents with 3 months history of chicken pox unresponsive to acyclovir.
What are next steps?
HIV test
Viral swab for genotypic resistance testing
