ID Ix Buzz

Question 1

Acute convalescent 4x rise in titre

Answer 1

Dengue Fever

Question 2

Gram negative diplococci on stain

Answer 2

Neisseria meningitidis (osce!)

Question 3

Positive cysts on blue tolludine stain

Answer 3

PJP

Pneumocystic jiroveci pneumonnia

Question 4

PCR for NPA

Answer 4

Influenza virus

Question 5

Acid fast bacilli on Ziehl-Neeson stain

Answer 5

Tuberculosis

Question 6

Pus containing sputum on culture with mixed oral flora

Answer 6

Pneumonia

Question 7

Urinary antigen for pneumonia

Answer 7

Legionella

Strep O titre

Question 8

Western Blot Test

Answer 8

Confirming test for HIV - highly specific

Do HIV Antibody test first - highly sensitive

Question 9

Urine antigen test, sputum staining withdraw I react fluorescent antibody (DFA), culture

Answer 9

Legionella

Question 10

Serologic testing, PCR polymerase chain reaction (pneumonia)

Answer 10

Chalmydophila / Chlamydia

Question 11

Clinical diagnosis. Serum cold agglutinins and serum __ antigen can be used. (Pneumonia)

Answer 11

Mycoplasma

Question 12

Urine pneumococcal antigen test + culture

Answer 12

Strep pneumoniae

Question 13

Nasopharyngeal aspirat,e rapid molecular tests for pathogen (influenza, respiratory syncytial virus), DFA, viral culture

Answer 13

Viral pneumonia

Question 14

Diagnosis of active TB disease

Answer 14

Mycobacterial culture of sputum (or blood, tissue) is the gold standard but can take weeks to obtain.
Sputum acid fast stain can yield rapid results - but lacks sensitivity
(red colour ‘red snapper’ of tubercle bacilli on acid fast staining)
CXR: cavitation infiltrate in upper lobe + calcification of lymph nodes (Ghon complex)

Question 15

Diagnosis of latent TB (asymptomatic and previous exposure)

Answer 15

Dagnose with a positive PPD (purified protein derivative aka Mantoux test) or Quantiferon -TB test.

• immunocompromised individuals with latent TB may have negative PPD
• patients with + PPD should be evaluated with CXR

Question 16

How to diagnose Influenza

Answer 16

Rapid viral antigen test with nasopharyngeal swab. (low sensitivity)
More definitive dx with DFA test, viral culture of PCR assay.

Question 17

Investigation for Meningitis

Answer 17

Obtain LP for CSF Gram stain and culture ideally before initiation of antibiotics. Check glucose, protein, WBC count, RBC count, opening pressure (in absence of papilloedema or focal neurological deficits).
Viral PCR (HSV), cryptococcal antigen (HIV patients)
CT or MRI for pt with altered mental state, papilloedema, or focal neurological deficits. If CT is being ordered, empirical antibiotics should be started.
Blood culture
FBE: leukocytosis.

Question 18

Investigation for encephalitis

Answer 18

CSF: lymphocytic pleocytosis, moderately high protein, low glucose for TB, fungal, bacterial, amebic infection.
LP: cell count, glucose, protein, culture for bacteria, fungi, mycobacterium, Gram stain, acid fast stain, INdia ink stain (Cryptococcus)
Order PCR: for HSV

Question 19

ELISA test and Western Blot test for what disease?

What further tests to help Diagnosis

Answer 19

HIV

ELISA test (high sensitivity, moderate specificity) Detects anti HIV Ab in bloodstream. Can take up to 6 months to appear
Western blot test: (low sensitivity high specificity) Confirmatory
Baseline evaluation -
*HIV RNA PCR (viral load)
*CD4+ cell count
* CXR
*PPD skin test of interferon gamma release assay (Quantiferon)
*Pap smear
*mental state exam
*VDRL/RPR
*Serology for CMV

Question 20

AIDS defining illnesses + opportunistic

The Major Pathogens Concerning Complete T Cell Collapse

Answer 20

Toxoplasma Gondi 
Mycobacterium avium intracellulare 
Pneumocystis jirovecii 
Candida albicans 
Cryptococcus neoformans 
Tuberculosis 
CMV 
Cryptosporidium parvum

Question 21

Gram stain shows budding test and or pseudohyphae

Answer 21

Candidiasis (thrush)

Presents with soft white plaques that can be rubbed off with an erythematous base. DDx is oral hair leukoplakia - lateral borders of tongue hard to rub off)
Treat with clotrimazole or fluconazole

Question 22

Cryptococcal antigen testing in CSF and or blood, CSF India ink stain and fungal culture

Answer 22

Cryptococcal meningitis
- Exposure to pigeon droppings,
Treat with amphotericin

Question 23

Urine and serum polysaccharide antigen test,

Fever weight loss, hepatosplenomegaly, lymphadenopathy, non productive cough, palatial ulcers, pancytopenia.

Answer 23

histoplasmosis (fungus)

Spelunking, caving, HIV patients = risk factor

Question 24

HIV patient with non productive cough and dyspnoea
Ix: cytology of induced sputu or bronchoscope specimen with silver stain and immunofluorescence
CXR: diffuse bilateralinsterstitialinfiltarate with ground glass appearance

Answer 24

Pneumocystis Jirovecii Pneumonia
- LUng tissue stained with silver uncovers cysts containing comma shaped spores

Treat with high dose TMP - SMX = aka BACTRIM

Question 25

Associated with retinal detachment - pizza pie. Retinopathy, floaters and visual field change
HEpatobiliary involvement.
PNeuomonitis
CNS involvement

Answer 25

Cytomegalovirus

Question 26

Diagnose with heterophil antibody (mono spot test)
Specific antibodies
FBE with mild thrombocytopenia, lymphocytosis and atypical T lymphocytes

Answer 26

Infectious mononucleosis

EBV