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Respiratory Block: Microbiology > HIV and the Lung > Flashcards

HIV and the Lung Flashcards

1
Q

HIV increases risk for what classes of pulmonary disorders?

A

Both infectious and non-infectious pulmonary disorders

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2
Q

What has impacted on the risk of pulmonary disorders in HIV positive patients?

A

Effective ART has impacted on the excessive risk

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3
Q

What is a common precipitating event that results in HIV unknown persons seeking medical attention?

A

Pulmonary conditions

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4
Q

What are commonly seen pulmonary conditions in the HIV positive population?

A
  • TB is common in areas with a high TB prevalence (SA)
  • Bacterial and Pneumocystis Jirovecii Pneumonia (PJP) are common pulmonary complications
  • Co-infection with multiple respiratory pathogens is common
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5
Q

What should be included in the differential when an infection is suspected in an HIV positive individual?

A

A very BROAD DIFFERENTIAL DIAGNOSIS:

  1. Cardiovascular
  2. Neoplastic
  3. INFECTIONS
    - Bacterial
    - Fungal
    - Viral
    - Parasitic
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6
Q

Approach to a suspected infection: what should be considered?

A
  1. Focus on more common conditions initially
  2. Consider history and clinical and radiographic findings
  3. Consider stage of immunosuppression
  4. PJP prophylaxis
  5. History of opportunistic infections
  6. Local epidemiology
  7. Receipt of ART
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7
Q

What is important to consider regarding the stage of immunosuppression if an infection is suspected?

A
  • clinical staging or CD4 cell count
  • worsening of immunosuppression increases risk of all infectious conditions
  • PJP usually CD4 <200
  • TB and bacterial pneumonia can occur at any stage
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8
Q

Why is it important to consider the receipt of ARTs?

A

IRIS!

- most common in the first 2 months of treatment

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9
Q

What is IRIS?

A

Immune Reconstitution Inflammatory Syndrome

- CD4 cell count improves due to treatment

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10
Q

What are the two types of IRIS manifestations?

A
  1. UNMASKING: occult pathogen has been in the body for a while but only now the immune system is able to mount a response = become symptomatic
  2. PARADOXICAL: excessive immune response fighting e.g. dead TB bacilli = makes it seem as though patient’s condition has suddenly deteriorated
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11
Q

What diagnostic tests can be done when an infection is suspected in an HIV positive patient?

A
  1. FBC with differential
  2. CXR
  3. Sputum for MC&S
  4. Blood Cultures
  5. Sputum for TB
  6. Sputum (induced) or bronchoalveolar lavage) for PJP immunofluorescence staining / PCR or serum for 1,2-beta-D-glucan (BDG) [adjunctive test]
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12
Q

What is Pneumocystis Jirovecii classified as?

A

An atypical fungus

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13
Q

What was Pneumocystis Jirovecii previously known as?

A

Pneumocystis Carinii (PCP)

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14
Q

Who is at markedly increased risk for Pneumocystis Jirovecii?

A

HIV positive patients with a CD4 count <200

- frequently however patient is not aware of their HIV status

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15
Q

What is the prognosis for Pneumocystis Jirovecii infection?

A

Prognosis related to severity of hypoxaemia at presentation, degree of immunosuppression and presence of CMV pneumonia.
Associated with significant short term mortality.

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16
Q

What is the clinical presentation of Pneumocystis Jirovecii?

A

Fever, SOB, non-productive cough

- impaired oxygenation

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17
Q

Pneumocystis Jirovecii: What is seen on chest X-Ray?

A

Bilateral diffuse infiltrates extending from the peri-hilar region

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18
Q

Pneumocystis Jirovecii: What diagnostic techniques should be used?

A
  1. CXR
  2. Induced sputum or BAL
    - Microscopy
    - PCR
  3. BDG
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19
Q

What is the treatment of choice for Pneumocystis Jirovecii?

A

Trimethoprim-sulfamethoxazole (co-trimoxazole / Bactrim)

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20
Q

What are possible alternative regimens for Pneumocystis Jirovecii?

A
  1. Clindamycin + Primaquine

2. Pentamidine

21
Q

What are possible alternative regimens for Pneumocystis Jirovecii for mild - moderate PJP only?

A
  1. Trimethoprim + Dapsone

2. Atovaquone

22
Q

Where can corticosteroids be of use in Pneumocystis Jirovecii Pneumonia?

A

For moderate - severe cases.

They dampen the inflammatory response and decrease the need for ventilation

23
Q

What else is very important in the management of Pneumocystis Jirovecii Pneumonia in many patients?

A

Initiation of ART
- early initiation = best outcomes
(bearing in mind IRIS)

24
Q

When should primary prophylaxis for Pneumocystis Jirovecii be given?

A
  1. CD4 <200

2. Infants born to HIV positive mothers from 6 weeks of age

25
Q

How should primary prophylaxis for Pneumocystis Jirovecii be given for infants born to HIV positive mothers?

A
  • stop when EFF & PCR negative
  • stop when no longer BF & PCR > 6 weeks later is negative
  • HIV positive infants < 12 months old must remain on prophylaxis
  • HIV positive 1-5 year olds until CD4 count >25%
26
Q

When should secondary prophylaxis for Pneumocystis Jirovecii be given?

A

If a patient had PJP, watch until CD4 >200

- wait 3 months to see if sustained, then can stop secondary prophylaxis

27
Q

What is given as prophylaxis for Pneumocystis Jirovecii?

A

Bactrim, but at a much lower dose than the therapeutic dose - 1 x / day vs. 4 x / day

28
Q

When do bacterial pneumonia infections occur in the HIV course?

A

The infections occur at all stages of HIV disease

  • increasing rates of pneumonia with declining CD4
  • even when on ART and normal CD4 count, rates of pneumonia are higher than in HIV-negative persons
29
Q

What are some of the common causes of bacterial pneumonia in HIV positive patients?

A
  1. Streptococcus Pneumonia and Haemophilus Influenzae are the MOST COMMON
  2. Staphylococcus Aureus and gram-negative bacilli are also frequent
  3. Nocardial infections can appear similar to TB
30
Q

What effect does HIV have on pulmonary tuberculosis?

A

HIV markedly increases the risk of TB disease:

  • reactivation
  • progression of primary disease
31
Q

What does clinical presentation of pulmonary tuberculosis in HIV positive patients depend on?

A

Clinical presentation depends on degree of immunosuppression

32
Q

What is active TB an indication for?

A

Active TB is an indication for initiation of ART irrespective of CD4

33
Q

What is seen regarding TB in patients with advanced immmunosuppression?

A

Disseminated disease and unusual pulmonary manifestations are more likely:

  • sputum microscopy may be less sensitive
  • culture and nucleic acid amplification tests
  • blood (and bone marrow) cultures (TB Bactec) biopsies (pleural, lymph node, liver)
34
Q

What are the fungal pneumonias (other than PJP) seen in HIV positive patients?

A
  1. Cryptococcus Neoformans (yeast)
  2. Histoplasma Capsulatum (dimorphic)
  3. Blastomyces Dermatidis (dimorphic)
  4. Aspergillus spp (mould)
35
Q

When are fungal pneumonias (other than PJP) likely to be seen?

A

When there is severe immunosuppression present

- usually CD4 of <100

36
Q

Where are symptoms of fungal pneumonia (other than PJP) seen?

A

Lung is the portal of entry and may be the site of initial symptoms, but haematogenous dissemination commonly occurs.

37
Q

How do cryptococcal infections usually present?

A

Cryptococcal infections usually present as meningitis

  • must exclude CNS / disseminated infection
  • with higher CD4 counts more likely to present with localized pulmonary disease
38
Q

What is common in fungal pneumonias (other than PJP)?

A

Co-infection with other pathogens common

39
Q

What treatment is used for fungal pneumonias (other than PJP)?

A

Amphotericin B combined with Fluconazole

40
Q

How does Histoplasmosis usually present?

A

Histoplasmosis commonly presents as disseminated disease

- fever, wasting, adenopathy, diarrhea, mucosal lesions together with pulmonary processes

41
Q

How is Histoplasmosis diagnosed?

A

Lab Diagnosis

  • serum or urine Histoplasma antigen test
  • culture of blood, bone marrow or liver biopsy
42
Q

How is Histoplasmosis treated?

A

Severe disseminated disease: Amphotericin B
Less severe disseminated disease: Itraconazole
+ ART!

43
Q

What is difficult about the diagnosis of viral pneumonia?

A

Difficult to attribute pulmonary disorder to viral pathogen that is identified in the absence of supporting histology.
- Virus may be a bystander

44
Q

What is a common dilemma with CMV?

A

Patients often have a concomitant PJP or bacterial pneumonia

  • CMV may be causing pneumonitis or bystander
  • patients with PJP and CMV pneumonitis have worse prognosis
  • BAL or biopsy
45
Q

How can you tell if CMV is the cause of pneumonitis seen and not a bystander?

A

Histology will show typical intracellular inclusions

46
Q

What is used to decide whether or not to treat a possible CMV pneumonitis patient with antivirals?

A

Serum CMV viral load is frequently used to aid in determining significance and thus in deciding whether to treat with Ganciclovir

47
Q

What can occur from influenza infection in HIV positive patients?

A

Influenza outcomes are thought to be worse in the HIV-infected
- Primary pneumonia due to influenza virus can occur

48
Q

What is a major complication of primary pneumonia due to influenza?

A

Bacterial super-infection is a major complication

49
Q

What parasitic pneumonias are seen in HIV positive patients?

A

Pulmonary involvement with parasitic infections is rare:

  • Toxoplasma Gondii
  • Strongyloides Stercoralis
  • Cryptosporidium spp
  • Microsporidiosis

Respiratory Block: Microbiology (7 decks)

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