MICRO: Infection CPC Flashcards
What is shown on this CXR?
- Bilateral shadowing
If you suspect atypical CAP but treatment does not work, patient is hypoxic and significantly desaturates on exercise,CT scan shows ground-glass opacity in both lungs, what should you suspect?
PCP pneumonia (pneumocystis jirovecii)
What is the treatment for PCP?
1st line: Co-trimoxazole 960mg BD
2nd line:Clindamycin + Primiquine (G6PD norm), IV methylprednisolone
What CD4 count should prompt you to start prophylaxis for PCP?
<200 cells/mm3
The arrow is pointing to a PCP cyst. What stain has been used here?
Methenamine silver stain (Grocott-Gomori)
At what time point is the viraemic peak in HIV infection?
4 weeks post-infection –> viraemic peak
Seroconversion –> symptoms (e.g. fever, rash)
Which type of lymphoid tissue does HIV tend to target?
gut-associated lymphoid tissue (GALT)
What is the major determinant of immune damage and short term outlook in HIV?
CD4 count
List some HIV-associated infections and the CD4 count at which they would be seen.
Describe the differences that may be seen in infections in the immunodeficient compared to non-immunodeficient patients.
Infectious agents may vary in type or frequency:
- Common agents common (e.g. pneumococcus)
-
Uncommon infectious agents arise (often not problematic in immunocompetent)
- Atypical mycobacteria
- Fungal
- Viral (CMV, HSV [i.e. reactivation])
- Other (e.g. toxoplasmosis)
Speed of progression may also be different
Presentation may be different
List 5 causes of immunodeficiency.
- Inherited
-
Acquired
- Iatrogenic
- Immunosuppressive agents
- Steroids
- Chemotherapy
- Radiotherapy
- HIV
- Chronic illness (diabetes, cancer)
- Malnutrition
- Iatrogenic
Name an infection associated with…
- T cell defects
- B cell defects
- Neutrophil defects
- Complement defects
Which types of infections are alcohol-dependent patients at risk of?
- Encapsulated organisms
- Indolent/slow growing organisms e.g. Actinomyces
What is actinomyces? What are the complications of actinomyces infection?
Actinomyces:
- Gram-positive rod that branches
- Closely related to Nocardia (another gram +ve rod)
Complications:
- Causes lung and brain abscesses in immunocompromised patients
- Difficult to treat
If you suspect Actinomyces, what must you tell the lab?
Notify the histopathologist and microbiologist that you are worried about actinomyces so they can start growing ASAP.
May need to keep on culture for longer and histopathologists can look for typical features