respiratory infections and HIV Flashcards
When was HIV identified
1984 HIV identified as a retrovirus and the cause of AIDS
Thought to have been transmitted from monkeys in the 1960s
what is the natural history of HIV
Primary infection - dec CD4 over weeks, slight inc and then a gradual dec over years
sharp inc in HIV RNA, peak at acute HIV syndrome, drop and slow inc over years (clinical latency) and sharp inc at constitutional symptoms, opportunistic diseases and death
what opportunistic infections are associated with a low CD4 count
Shingles <400
TB
oral thrush
PCP
Fungal meningitis and cerebral toxoplasmosis
CMV retinitis, MAI PML, cryptosporidosis <50
how has HIV treatment progressed over the years
rapidly lethal then via incremental therapeutic advances to a manageable long term condition
ART (antiviral therapies) means that life expectancy is almost normal and quality of life in far improved
what are comorbidities of HIV
CVD chronic kidney disease chronic liver disease cancer frailty COPD cognitive decline polypharmacy diabetes mellitus
how can HIV be tested for
Rapid HIV test – finger prick
Confirmatory HIV test
what respiratory infections are associated with chronic HIV CD4 count
Linked to
On effective cART
CD4 count
Other comorbidities
>500 - community acquired pneumonia, other URTI and TB
>350 - PCP, other HIV related pneumonia (fungal, viral, CMV, bacterial), TB
types of HIV related respiratory infections
PCP pneumonia
Bacterial pneumonias (CAP and HAP)
Pneumococcal pneumonia, H influenza, staph aureus and atypical agents (C and M pneumoniae)
Fungal pneumonias
Aspergillosis, cryptococcis, histoplasmosis
Viral pneumonias
Influenza, CMV pneumonitis, TB
what is PCP
Ubiquitous in the environment
Initial infection usually occurs in early childhood.
May result from reactivation or new exposure
In immunosuppressed patients it can possibly spread airborne
who often has PCP
Before ART 70-80% AIDS patients with PCP
In advanced immunosuppression, treated PCP associated with 20-40% mortality
Substantial decline in high income settings – prophylaxis and ART
Most causes patients unaware of HIV infection eg not in care or advanced AIDS (CD4 <100)
PCP risk factors
CD4 <200
CD4 <14%
Prior PCP
Oral thrush
PCP symptoms
Recurrent bacterial pneumonia
Unintentional weight loss
High HIV RNA
clinical manifestations of PCP
Progressional exertional dyspnoea, fever, non productive cough and chest discomfort
Subacute onset, worsens over days-weeks (fulminant pneumonia is uncommon)
Chest exam may be normal or diffuse dry rales, tachypnoea, tachycardia (esp exertion)
Extrapulmonary disease seen rarely, occurs in any organ, associated with aerosolized pentamidine prophylaxis
How is PCP diagnosed
Clinical presentation, blood tests, radiographs suggestive but not diagnostic
Organism cannot be cultured, definitive diagnosis should be sought
Hypoxaemia: characteristics mild or severe
Low LDH uncommon but non specific
1,8B-D-glycan may be elevated, uncertain sensitivity and specificity
HRCT scan of chest showing PCP. Bilateral patchy areas of ground-glass opacity are suggestive of PCP
can PCP be seen on X-ray
Normal in early disease
Typical diffuse bilateral, symmetrical interstitial infiltrates
Atypical including nodules, asymmetric disease, blebs, cysts, pneumothorax
Cavitations, intrathoracic adenopathy and pleural effusion uncommon (unless second concurrent process)
how is PCP diagnosed definitively
Induced sputum - spontaneously expectorated sputum
Bronchoscopy with bronchoalveolar lavage
Transbronchial biopsy
Open-lung biopsy
PCR: high sensitivity for BAL sample; may not distinguish disease from colonization
when is treatment for PCP initiated
be initiated before definitive diagnosis is established
Organism persists for days/weeks after start of treatment
what is the primary prophylaxis of PCP
Initiate Consider CD4% <14%, AIDS illness history, CD4 200-250 if cannot monitor for 3 months Discontinue On ART CD4>200 for >3 months Reinitiate CD4 decreases to <200
How is PCP treated
preferred Septrim although there are alternatives
21 day regimen for all treatments
what are PCP risk factors
Age cART HIV Pollution? Recreational drug use Comorbidities Smoking
what respiratory infections are seen in the cART era
High Income settings: CD4>250 Bacterial pneumonia Hospital acquired pneumonia Other respiratory conditions: COPD, asthma, Lung cancer TB COVID-19 pneumonitis Low income settings and CD4<250 All of above plus PCP Fungal pneumonias TB COVID-19 pneumonitis
how can respiratory infections be prevented in HIV+
- Seasonal flu vaccine
- Pneumovax vaccine
- COVID-19 vaccination
- Smoking cessation
- Substance abuse counselling
- cART
