HIV Flashcards
What is the risk of developing TB in HIV?
26-31x higher in HIV population hence why if TB+ve should always check HIV status
In the UK when assessing patients with HIV for LTBI what test do you do ?
IGRA
If first result indeterminate/borderline then repeat within 4 weeks, if remains indeterminate then clinician discretion
What is the treatment regimen for drug sensitive TB in HIV positive patients ?
Standard TB therapy
Where antiretroviral therapy necessitates the use of Ritonavir boosted protease inhibitor what change to medication is required ?
Rifampicin is replaced by Rifabutin
In HIV patients with Isoniazid Resistant TB, what is the drug regimen?
Rifampicin, Pyrazinamide, Ethambutol, Levofloxacin
What is the timing in which ART is given to newly diagnosed HIV , TB positive patients?
All newly diagnosed HIV patients with TB , irrespective of their CD4 count are offered ART as soon as practical within 4 weeks of diagnosis .
If CD4 count <50 should be within 2 weeks
If CNS TB , delay initiation of ART for 8 weeks
What is the ART regimen usually started for those taking Rifampicin based anti-TB meds ?
Efavirenz (Raltegravir/ Dolutegravir)
+
Tenofovir Deproxil
+
Emtricitabine
Do individuals who develop TB on ART with undetectable viral loads need any changes to ART?
No , continue same regimen
(NB if needing Ritonavir boosted PI then switch Rifampicin to Rifibutin ; avoid Combicistat with Rifampicin/Rifabutin )
What is Immune Reconstitution Inflammatory Syndrome in TB with HIV?
Paradoxical worsening of disease (worsening fever , CXR infiltrates, increased lymphadenopathy or new manifestations of the disease) at the initiation of HIV treatment . Represent restoration of the pathogen specific immune responses , steroids reduce morbidity associated with IRIS
Outline differences seen in HIV and TB co-infection
In HIV and TB co-infection clinical and radiological presentation of TB may be atypical compared with immunocompetent and more likely to have a normal CXR and be smear negative but culture positive
What is the gene that confers resistance to Rifampicin?
rPoB
Why do patients with HIV get chest infections?
The immune dysregulation associated with HIV results in an increased risk of respiratory infections at all CD4 counts. Widespread use of prophylaxis has reduced risk of life threatening infection but not returned to background levels of negative HIV population
Most common is PCP and bacterial pneumonia
What increases a patients risk of opportunistic infections (OI) in HIV?
- Patients use of OI prophylaxis
- Recent dx from hospital or current IP >5 days
- Country of residence /travel
- Hx of active lung disease
- Level of host immunity
- Neutropaenia
- Prolonged cause of immune modulation (steroids)
What is Pneumocystis Jirovecii?
Fungus
Who gets PCP?
90% of cases are in HIV seropositive patients with CD4 counts <200
Other predictive factors:
- non adherence to prophylaxis
- oral candidiasis
- oral hairy leukoplakia
- unintentional WL
- recurrent bacterial pneumonia
- previous PCP
- high HIV viral load
How does PCP present ?
Exertional dyspnoea progressing over several weeks with malaise and dry cough , inability to take a deep breath in and fever often apparent
Exam often normal (can have end inspiratory crackles) , spontaneous or infection associated PTX should prompt exclusion of PCP
What does the radiology demonstrate in PCP?
Perihilar haze , interstitial infiltrates (characteristically sparing the apices and costophrenic angles) pneumoatocoeles and pneumothorax but can have normal CXR
Radiology not sensitive/specific for dx
How do you diagnose PCP?
Induced sputum (sensitivity 50-90%)
BAL
(Open lung biopsy- if not improving and prev no result)
** spontaneously expectorated sputum is not adequate alveolar sample and should not be processed**
Remember Pneumocytis Jitovecii cannot be cultured in vitro and diagnosis relies on visualization of the organism (Histochemical - silver stain such as Gregory Gimori or immunofluoro) OR NAAT
** do not delay treatment for the procedure as samples will remain positive 7-10 / 7 into treatment
What is the treatment for moderate/severe PCP (PaO2 <9.3 or sats <92%)
High dose IV Co-Trimoxazole and IV/PO steroids, can be switched
IV Co-Trimoxazole 120mg/kg/day TDS/QDS for 3/7 and then 90mg/kg/day TDS/QDS for 18/7
Prednisolone 40mg BD for 1-5 days , then 40mg OD for 6-10 days, then 20mg OD for 11-21 days (if can’t take oral can have IV methylpred at 75% of the dose)
When are corticosteroids of benefit in PCP?
PaO2 < 9.3 or sats <92%
if started within 72 hours of specific anti PCP therapy
