Microbiology 3S: Infection CPC Flashcards
Diagnosis?
Community Acquired Pneumonia → Infective exacerbation of COPD
Tx of Community Acquired Pneumonia?
co-amoxiclav + clarithromycin
Describe this CT chest. What does it show?
- patchy consolidation + ground-glass opacity in both lungs;
- predominant in upper and mid-zones in distribution
- = PCP (pneumocystitis pneumonia)
What should be conducted after ground glass opacities are seen on CT chest?
- sputum induction,
- expectorated sputum has poor sensitivity, should not be used
- → direct fluorescent-antigen testing → +tive for Pneumocystis
if sputum negative:
- → bronchoscopy + bronchoalveolar lavage
- → stained with Grocott-Gomori methenamine-silver stain → +tive for Pneumocystis
What is the typical clinical picture of PCP?
- SoB ON EXERTION (reduced exercise tolerance)
- low O2 sats
- SpO2 tends to drop on exertion more
- CXR = fairly normal,
- CT = ground-glass shadowing (widespread, bilateral)
Algorithm for PCP diagnosis if clinically suspected?
Causative organism of PCP?
Pneumocystis jirovecii pneumonia
Tx for PCP? Risks?
- 1st line: co-trimoxazole 960mg BD
risk: widespread erythematous rash → co-trimoxazole stopped → OD prednisolone - 2nd line: Clindamycin + Primiquine (G6PD norm) + IV methylprednisolone
Diagnosis?
PCP
Diagnosis?
What does this show (bronchoalveolar lavage from bronchoscopy)?
What stain has been used?
- The arrow is pointing at one of the cysts (PCP)
- Visualised using a methenamine silver stain (Grocott-Gomori)
Epidemiology of PCP?
- AIDS defining illness of lung
- commonly found in HIV +tive patients or those who are immunosuppressed
What is the natural history of HIV-1 infection?
-
Seroconversion (development of specific antibodies in the blood serum as a result of infection or immunisation) → symptoms
- (e.g. fever, rash)
- Eventually, viral load falls & CD4 count recovers
- Then asymptomatic, which can last for years
- Eventually, viral load rises & CD4 count falls
- Then, immunocompromised and at risk of AIDS-defining conditions e.g. PJP/PCP
Which parameter is a major major determinant of immune damage in HIV?
CD4 count
Which conditions can develop as CD4 count falls in the later months/years of HIV infection?
What are the infection agents in HIV?
- Common agents (e.g. pneumococcus)
-
Uncommon agents (often ubiquitous but cause no problem in immunocompetent patients)
- Atypical mycobacteria
- Viral (CMV, HSV [i.e. reactivation])
- Fungal
- Other(e.g.toxoplasmosis)
How does the presentation of infections vary in HIV +tive patients vs HIV -tive?
- Normally, the symptoms of an illness are due to the immune response rather than the pathogen itself
- So, the presentation in HIV can be quite abnormal (due to immune compromise)
- I.E. may present with miliary TB or TB meningitis
- Speed of progression may also be different