Clinical scenarios Flashcards
Incubation period of TB
> 2 years
Pathogen for Rasmussen’s aneurysm
MTB (complication of pulmonary TB)
Diagnosis of active TB (3, in details)
- Microscopy (AFB / Ziehl & Neelsen stain)
- Culture (Lowenstein-Jensen medium / broth)
- PCR (GeneXpert MTB)
Culture time for TB
Solid: 6~8w
Liquid:1~3w
Screening for latent TB: indications (2) and methods (2)
Indications: clinical suspicion / contact of TB patients
Methods: Tuberculin skin test, IFN-γ release assays
Principle, procedure (how many days), and result of tuberculin skin test
Principle: Type IV HSR
Procedure: inject intradermal tuberculin material –> measure area of induration after 2 days
Result: area of induration >10mm => positive
FP (2) & FN of tuberculin skin test
FP: BCG vaccine, NTM
FN: immunocompromised, HIV, advanced TB, acute illness…
Principle and FP of interferon-γ release assays
Principle: inject antigen –> stimulate T cells to secrete IFN-γ
FP: NTB
Treatment for active TB
2 HRZE + 4 HR
Treatment for latent TB
Isoniazid 6 months
DDx of STDs (painless ulcer, painful ulcer, bubo)
Painless ulcer: syphilis
Painful ulcer: chancroid, genital herpes
Bubo: lymphogranuloma venereum, chancroid
Clinical course of syphilis
incubation period: 6 weeks
1. Primary syphilis:
- painless chancre
- resolve in 6 weeks
2. (after 6 weeks) Secondary syphilis:
- maculopapular rash starting from extremities
- condyloma latum [genitalia]
- systemic infection
- resolve in 6 weeks
3. Latent syphilis
- 66% resolve completely
4. (after >6 years) Tertiary syphilis
- Gumma
- Aortitis, Aneurysm
- Neurosyphilis (Tabes dorsalis, Argyll-Robertson pupils…)
Diagnosis of syphilis (active, latent)
Active: darkfield microscopy of fresh exudate from lesions
Latent:
- Non-specific test
a. VDRL test (venereal disease research lab)
b. RPR test (rapid plasma reagin)
- (further confirm by) Specific test
a. TPPA test (Treponema pallidum particle agglutination)
b. FTA-abs test (Fluorescent Treponema Antibody-absorption)
Treatment for syphilis
IM benzathine penicillin
(if resistant: doxycycline)
Presentations of gonorrhoeae
[female] asymptomatic
[male] urethritis
Treatment for gonorrhoeae
IM Ceftriaxone once
Diagnosis of gonorrhoeae
microscopy & culture of urethral discharge / endocervical swab
MC STD
Non-gonococcal urethritis
Treatment of non-gonococcal urethritis
PO Doxycycline + Azithromycin
Pathogen for chancroid
Haemophilus ducreyi
Pathogen for warts (serotypes?)
HPV serotypes 6,11
What cancer is associated with HPV? (which serotypes?)
CA cervix (16,18)
Pathogen for molluscum contagiosum
Poxvirus
Risk factors for candida vaginitis (3)
antibiotics
hormonal imbalance (e.g. OCP)
DM
Pathogen for white cheesey discharge + pruritis vulvae
Candida vaginitis
Presentations of STD candidiasis and trichomoniasis respectively in male
Candida: balanoposthitis
Trichomoniasis: asymptomatic
Pathogen for malodourous, foamy vaginal discharge
Trichomonas vaginalis
Treatment of vagina trichomoniasis
tinidazole, metronidazole
Vaginal discharge showing clue cell: which pathogens? (3)
Gardnerella vaginalis, Peptostreptococcus, Prevotella
Treatment for bacterial vaginitis
metronidazole
Bacteraemia vs Septicaemia
Bacteraemia = bacteria in blood
Septicaemia = active multiplying bacteria in blood
4 Criteria for SIRS (what’s its full form?)
(Systemic inflammatory response system)
1. Temperature: >38 or <36
2. Tachycardia: >90
3. Hyperventilation: RR>20 or PaCO2<32
4. WBC abnormality: >12 or <4, or >10% immature forms
SIRS vs Sepsis
Sepsis = evidence of infection + SIRS / SOFA score
What is SOFA score? Name some parameters inside (7)
Sequential organ failure assessment score
Parameters: MAP, Plt, PaO2, bilirubin, Creatinine, urine output, GCS score
Septic shock vs sepsis
septic shock = sepsis + hypotension
What is superantigen?
Ag that binds to TCR & MHC-II directly –> causing non-specific T-cell activation
Workup for sepsis
- Blood culture for >= 2 times from different anatomical sites, 1 hour apart
- aerobes, anaerobes, TB, fungi
- microscopy, culture, stain, sensitivity test from every possible specimen (e.g. sputum, urine, CSF, tissue from obvious wound…)
- serological studies, molecular studies
- CBC, LRFT
- CXR
Pathogens for Waterhouse-Friderichsen syndrome (What is it?)
Neisseria meningitidis, Pseudomonas aeruginosa
(severe sepsis –> bilateral adrenal haemorrhage –> adrenal insufficiency)
Pathogen and toxin for toxic shock syndrome
S. aureus. TSST-1
Presentation of toxic shock syndrome 1~3w later
desquamation of palms & soles
PUO definition
temperature >38.3 for >3w without diagnosis after >1w of investigations in hospital
Causes of PUO
Infection > Neoplasm > Connective tissue disease > no diagnosis
Microbiological investigations for tropical travellors (3)
serology, thick blood smear, blood culture
Pathogen and vector (be specific) for malaria
Plasmodium spp.
Anopheles mosquitoes
Pathogenesis and protective factor of malaria
Pathogenesis: invade RBCs –> dysfunction + plug up post-capillary venules in organs
Protective factor: sickle cell anaemia trait
Pathogen for severe malaria
Plasmodium falciparum
Diagnosis of malaria
thick & thin blood smears
rapid diagnostic test (ParaSightF)
Thick vs thin blood smear
Thick: best for screening
Thin: best for speciation & monitoring
Prophylaxis for malaria (4)
chloroquine, mefloquine, doxycycline, primaquine
Management for malaria (3)
- Anti-malarial chemotherapy
- Monitor blood smears
- Avoid sedation & steroids
Anti-malarial chemotherapy (3)
Complicated falciparum: IV Artesunate
Uncomplicated falciparum: PO coartem
Non-falciparum: Chloroquine
Presentations for typhoid fever (4)
pulse-temperature deficit, rose spot, splenomegaly, leukopenia
Disease with pulse-temperature deficit
Typhoid fever
Disease with rose spot
Typhoid fever
Complications of typhoid fever (4)
Intestinal haemorrhage, intestinal obstruction, encephalopathy, nephritis
Diagnosis and treatment (2) of typhoid fever
blood culture
FQ, 3GC
Definition of MDR and XDR in typhoid fever
MDR: ampicillin, chloramphenicol, septrin
XDR: resistance to FQ, 3GC
(SAC QC)
Vaccination for typhoid fever (2)
live attenuated
oral (ty21a) or parenteral (Vi polysaccharide)
Pathogen for break bone fever, retroorbital pain
Dengue virus
3 types of presentations of dengue fever
- Classic Dengue fever
- Dengue haemorrhagic fever
- Dengue shock syndrome
Treatment regimen for Pott disease
2HRZE + 10HR
Alcoholic hand rub formulation 1 & 2 difference
ethanol 96%
isopropyl alcohol 99.8%
Contact precautions (3)
Use of PPE especially during procedures that produce splashes
Isolation room / cohort nursing
Clean the environment with 1:49 hypochlorite after discharge
Definitions of droplet and airborne
droplet >5µm in diameter, fall by gravity in 1m
droplet <5µm in diameter, able to travel >3m
Droplet precautions
Sugical masks, social distancing 1m
Airborne precautions
Negative pressure isolation room (>6 air changes per hour)
double door system
Fit-tested N95 mask (patient with surgical mask during transport
Transmission risk of HBV, HCV and HIV in needle sharp injury
30%, 3%, 0.3%
Algorithm of HBV status assessment after needle sharp injury
if HBsAg +ve: refer to hepatologist
if HBsAg -ve & anti-HBs IgG: offer 3 dose vaccine –> post-vaccination HBsAg check
if unable to produde sufficient IgG: 3-dose trial once more
if still unable: hypo- / non-responder –> post-exposure prophylaxis
If anti-HBs IgG +ve: no vaccination required
Presentations of congenital varicella syndrome (6)
low birth weight, cutaneous scarring, limb hypoplasia, microcephaly, ocular abnormalities, mental retardation
Management of STD
- antibiotics
- contact tracing + treat sexual partners
- screen for other STDs
- avoid sexual intercourse until treatment completes
- retest all patients ~1 month after treatment to ensure cure
Workup for vaginal discharge
- Specimens: vaginal discharge, vaginal swab
- Investigations:
- Gram stain: look for clue cells
- fungal culture: look for oval-shaped yeast with hyphae
- microscopy in Feinberg medium: look for pear-shaped trophozoites with jerking movement
- PCR
Which pathogen causes general paresis of insane?
Treponema pallidum (presentation of neurosyphilis)
Risk factors for decubitus ulcer
immobility, DM, malnutrition, ↓ perfusion, sensory loss
What is Mantoux test?
a type of tuberculin skin test
Full name for PCV13 and PPSV23
protein conjugate vaccine
pneumococcal polysaccharide vaccine
Household sodium hypochlorite concentration
(what ratio is used for: daily cleaning? vomitus? blood?)
50000 ppm
(1:99, 1:49, 1:4)