Opportunistic infections in HIV Flashcards
What happens when CD4 < 400?
At CD4 < 400, the body starts to rot (RROOT):
- Reactivation VZV, Reactivation TB
- Oral candidiasis
- Other bacterial infections (H influenzae, Salmonella, S pneumoniae)
- Tinea pedis
What happens when CD4 < 200?
At CD4 < 200, the patient starts to be a prick (PRICC):
- Pneumocystis jirovecii (PCP)
- Reactivation HSV
- Isospora
- Coccoidomycosis (disseminated), Cryptosporidiosis
What happens when CD4 < 100?
At CD4 < 100, the end is near (THE):
- Toxoplasmosis
- Histoplasmosis
- (O)esophageal candidiasis
What happens when CD4 < 50?
At CD4 < 50, the patient is a statistic with the CDC (CDC):
- CMV retinitis and oesophagitis
- Disseminated MAC (Mycobacterium avium complex)
- Cryptococcal meningitis
What are the the symptoms of PCP in a HIV patient?
- Gradual onset over a period of weeks (compared to days in bacterial pneumonia)
- Prominent exertional dyspnoea (SOBOE) until cannot climb stairs (more severe than normal community acquired pneumonia), non-productive cough, fever, malaise
What are the signs of PCP in a HIV patient?
- Tachypnoea, tachycardia, cyanosis, hypoxemia (worsened on exertion)
- Mild cases -> no auscultatory abnormality
- Occasional bilateral fine crackles
How is PCP diagnosed in a HIV patient?
CXR -> normal in early infection, bilateral perihilar interstitial infiltrates later
CT thorax -> ground-glass opacity (GGO) appearance
Diagnosis
- Ix TRO TB
- Techniques -> induced sputum preferred but may be insufficient. If insufficient 🡪 bronchoalveolar lavage (BAL) (yield > 95%), transbronchial biopsy, open lung biopsy.
- Silver staining -> staining of cyst wall, or cyst and trophozoite staining
What is the treatment for PCP in a HIV patient?
First-line: cotrimoxazole (TMP/SMX) (aka Bactrim)
- If sulfa allergy: Clindamycin + primaquine (second line); IV pentamidine (third-line, can also use in G6PD, but many S/E), dapsone (C/I in G6PD)
Indications for adjunctive steroids (prednisolone, initiate concurrently with anti-Pneumocystis)
- Severe disease, i.e. hypoxia/hypoxaemia (PaO2 < 70mmHg, A-a gradient > 35mmHg)
- May reduce fever
- Abx 🡪 lysis 🡪 inflammation (prevented by steroids)
- Balance with concern for S/E of systemic steroids, e.g. PUD with BGIT 🡪 consider gastroprotective agents (e.g. omeprazole)
Initiate HAART
- Maintenance therapy/2’ prophylaxis (TMP/SMX) required until CD4 > 200 for > 3 months (using 2 blood tests done over 2 visits)
- Prior infection is not a protective but a risk factor for recurrent PCP
What are the clinical features of cryptococcus in a HIV patient?
Insidious onset, w/ non-specific fever, N&V and headache
Progresses to altered mental status (AMS)
Uncommon features
- Seizures or focal neurological deficits
- Neck stiffness and photophobia (uncommon as these depend on inflammatory response, which is abnormal)
How is cryptococcus diagnosed?
Serum cryptococcal antigen (highly specific/sensitive, approaching 100% for HIV+ patients)
Do lumbar puncture (after CT brain if indicated) -> India ink staining of CSF for yeast, culture (note India ink has only 50% sensitivity, but high specificity [100%])
- High opening pressure
- Protein: mildly elevated
- Glucose: low-normal
- Cells: lymphocyte-predominant
- Positive CSF Cryptococcal antigen
What is the management of cryptococcus in a HIV patient?
Amphotericin B + 5-flucytosine (2 weeks) monitor renal function (amphotericin B)
Followed by fluconazole (8-10 weeks)
Maintenance therapy: Fluconazole until CD4 > 100 for > 3 months
Delay HAART until 2 weeks after commencement of Cryptococcal treatment, do not start simultaneously; this is to ↓ risk of IRIS (immune reconstitution inflammatory syndrome)
Management of raised ICP: elevated LP KIV shunt insertion
What are the clinical features of CMV retinitis in a HIV patient?
Usually starts unilaterally (2/3), but may progress to involve both eyes
Presentation depends on area of retina involved
Regular fundoscopy recommended when CD4 < 50
Clinical features
- Asymptomatic (smouldering infection, can flare up when ART is started (CMV-IRIS), leading to sight threatening complications 🡪 screen in all HIV+ before starting ART)
- Visual loss (macular involvement), floaters, loss of visual acuity, field loss and scotomata
- Headache and orbital pain
- Fundoscopy -> haemorrhages and exudates following vasculature of retina (‘brush-fire’ appearance)
What is the management of CIV retinitis in a HIV + patient?
cutely
- Ganciclovir x2-3/52, monitor FBC 2x/52 (Ganciclovir has risk of myelosuppression)
- Foscarnet x2-3/52, monitor U/E/Cr (give if already pancytopenic, risk of nephrotoxicity)
Maintenance -> ganciclovir (until CD4 > 100 for > 3-6 months), foscarnet
how do tb +, hiv+ patients present?
Pts w good CD4: same clinical picture as HIV-negative individuals
More advanced HIV
- May have atypical pTB presentations – no cavitation and prominent hilar lymphadenopathy, no granulomatous response, bibasal pneumonia
- Extra-pTB and disseminated disease much more common (lymph nodes, meningitis, osteomyelitis, hepatosplenomegaly), because insufficient immune response 🡪 unable to contain TB
how is tb diagnosed in HIV + patients?
- Mantoux/PPD test (TST) is blunted in HIV+ pts and is unreliable
- Sputum smear and microscopy less sensitive (as low bacilli per ml of sputum if no cavitating response) -> may be negative in pulmonary infection
- AFB smear and c/s is best diagnostic tool
