| What is meant by opportunistic lung infections? | Due to intensified immunocomprimised, prolonged survival, abx resistance and improved dx assays, they are increasing.
It is defined as infection in pt with increased suseptibility to infection (even to those with little native virulence in normal individuals
Each host group has enhanced susceptibility to a subset of pathogens (according to cause of immune defect)
Survival has improved with new antimicrobial agents, but they still remain most common form of opportunistic infections (pulmonary infections) |
| What are general considerations in opportunistic lung infections? | Multiple infections (CMV+pneumocystitis, post-viral)
Early imaging and microbio imp for immunocomprimised, need invasive procedures for dx, specific microbio dx imp, microbicidal therapy started early, empiric therapy, reduction of immunosuppression with infection needed for tx success.
Most immunocomprimised pt with any sign of infection should hospitalized, serology not useful (can't make Igs)
CXR/CT done |
| What are infections associated with neutrophil disoders? | Gram -, SA, other staph, strep, fungi (neutropenia, neutrophil chemotaxis, killing) |
| What are infections associated with T cell def? | Viruses (herpes), Nocardia, parasites, histoplasma (in HIV, lymphoma, chemo, transplant and T depleting Ab, calcineurin use, rapamycin inhibitors use) |
| What are infections associated with B cell def? | Encapsulated bacteria, salmonella, campylobacter, giardia (in myeloma, leukemia, burns, plasmapheresis...) |
| What infections are associated with spleen and complement defects? | Encapsulated bacteria and SA |
| What is neutropenia? | Most common risk factor of these infections, depth and duration of it is correlated with risk for infection.
Rates of infection depend on host, nosocomial infections occur for 46 days of 1000 days of neutropenia
Origin cannot be seen for febrile cancer pt, usually from URT/ LRT/ GI/ urinary/ skin, many detected only in autospy |
| What is role of glucocorticoids in these infections? | Imp cause of depression of phagocytic action, mobilization of inflammatory cells and alteration in Ag presentation and lymphocyte mobilization.
Increase risk of infections, and pulmonary involvement in other infections (such as herpes -CMV/VZV) |
| What is role of biologic agents in opportunistic infections? | TNF-a inhibitors/ blockade of inflammation
Predispose infection of intracellular pathogens (mycobacteria/ legionella), systemic viral or fungal infections (molds, yeasts...) |
| What are HIV-related lung infections? | Pneumocystitis pneumonia (PCP) most common (but declining by prophylaxis).
Bacterial mostly, TB (at least 1/3 of cases of HIV), 5.5-29% of HIV pt get pneumonia (compared to 0.7-10% in non HIV pt)
Viral (CMV), fungi and parasites
As CD4 declines ->more incidence of infection (highest risk in IV use, smoker, developing countries and city inhabitant) |
| What are etiologies of CAP? | Strep pneumo, pseudomonas, other....
Bacterial tracheaitis and bronchitis associated with broncheictasis (S.pneumonia, H.flu, SA, pseudomonas) |
| What are clinical manifestations of HIV-pneumonia? | Similar to other pneumonia, fever, chills, cough, sputum, dyspnea, pleuritic pain, leukocytosis (except in advanced suppression)
Bacteremia (60% of S.pneumo), bronchitis with bronciectasis, tracheitis (may present with S&S of UA obstruction) |
| What are image findings of HIV-pneumonia? | Most common is segmental or lobal consolidations (reticulonodular infiltrates are also common)
CT defines nature (ground-glass ->P.jiro/viral/ atypical bacteria |
| How is the diagnostic evaluation of HIV pneumonia? | CXR, sputum cutlure, CBC, urinary Ag test (S.pneumo and legionella and viral), thoracocentesis (pt with pleural effusion/ empyema)
Help determines if we change course of suppression or not, and which Abx to use.
Look for TB (PPD test) |
| What is tx of HIV pneumonia? | Initial Abx, acc to pt status and reliability either inpatient or outpatient. |
| How is Pneumocystis pulmonary infection in HIV-pt? | Incidence is declining with ART (antiretroviral therapy) and prophylaxis.
but it is one of the leading causes of infections in HIV with low CD4, recognized as a fungus, used to be a protozoan, but they are atypical fungi (don't grow in cultures, cell wall with cholesterol)
Airbourne transmission, primary infection occurs by age of 4 usually, remains latent until immunosupressed, exists in alveoli exclusively, attach epithelium and macrophages |
| How is pathogen-host interaction of pneumocystitis? | Macrophages mediate their clearance, by phagocytosis, respiratory burst and inflammation after seeing beta-glucan molecules present at cell wall and MSG (major surface glycoprotein).
In HIV pt these are impaired, risk factors include immunosupression with no ART, CD4<200, previous episodes of PCP, oral thrush, recurrent pneumonia, weight loss. |
| What are clinical manifestations of PCP? | Gradual onset, fever, cough, dyspnea progressing over days- weeks
Symptoms for 3 weeks average, non-productive cough.
Fatigue, chills, pain and weight loss occurs, and 10% are asymptomatic, tachypnea is present
Adventitial sounds: crackels and ronchi
Oral thrush ->co-infection |
| What are lab findings of PCP? | Low CD4 (<200/ less than 14%)
Hypoxia (widened A-a gradient mild <35 to severe>45, desaturation with exercise)
Lactate Dehydrogenase elevated (90%)
1,3-beta glucan (elevated)
Diffusion capacity DLCO low |
| What are radio manifestations of PCP? | CXR: normal up to 1/4 of pt, most commonly diffuse, bilateral interstitial or alveolar infiltrates, upper lobe infiltrates and pneumothorax may be de novo. less common: lobal infiltrates, cysts, nodules, pleural effusions
HRCT: high sensitivity, patchy/nodular ground-glass attenuation (not dx, suggestive of PCP)
Gallium-67 nuclear scan: not very used |
| How is definitive dx of PCP done? | Visualization of cytic/ trophic form in respiratory secretions of PCP, important to get definitive dx since tx is toxic prolonged therapy, 15% have concurrent cause of disease. |
| What stains identify PCP? | Cystic form: gomori-methenamine silver, cresyl violet, Gram-weigert, toluidine blue O
Cystic and Trophic form: Wright-Geimsa, Diff-Quick (not cell wall)
Immunofluorescence most preferred and sensitive |
| How is PCR use in PCP? | of respiratory fluid (BAL), confirms dx, but cannot distinguish between colonization and disease |
| How to get optimal specimens? | Sputum induction (least invasive, inhalation of hypertonic saline)
Bronchoalveolar lavage (BAL) (Dx: 90-100% in HIV, sampling of most heavilty invovled lobe)
Tissue biopsy (transthoracic (30% risk of pneumothorax), thoracotomy (sensitivity 95-100%) |
| How is tx of PCP? | Mild disease (O2 gradient <35, oral therapy TMP-SMX, no corticosteroids)
Moderate disease (between 35-45, oral therapy TMP-SMX and corticosteroids)
Severe disease (IV TMP-SMX, corticosteroids alternative clindamycin-primaquine (if desenstized to sulfonamide SMX)
Without steroids pt may worsen after 2-3 days of therapy, prednisone 40 mg twice daily for 5 days ,then once for 5 days then 20mg daily for 11 days |
| How is toxoplasma pneumonia and other parasitic pneumonia in HIV pt? | Most active T.gondii due to reactivation after HIV, 30% develop encephalitis within 2 years of AIDS without ART, 1% develop primary toxoplasmosis |
| How is clinical presentation of toxoplasma with HIV? | CD4<100 to become active, pneumnia (fever, cough, dyspnea), CXR (diffuse bilateral interstitial and alveolar infiltrates), nodules, cavitary infiltrates, lobar pneumonia, pleural effusions. |
| How is dx of toxoplasma with HIV? | Serology (but not helpful), BAL preferred method of dx nuy geimsa stain of BAL fluid |
| How is treatment of toxoplasma with HIV? | Pyrimethamine and sulfadiazine , when limited access go for TMP-SMX |
| Talk about CMV infection in HIV pt. | Seen in late stages of HIV, BAL culture or PCR (not specific for CMV pneumonitis), Tx: for symptomatic pt only, when concomitant pathogens are present |
| What are HIV-related lung diseases? | Kaposi Sarcoma, Lymphoma and Lung cancer (malignancies)
Other non-infectious (lymphoid/nonspecific pneumonia, pulmonary HTN, COPD) |
| What is Kaposi Sarcoma? | Low grade vascular tumor with HHV8, decreased with ART.
Symptoms: SoB, cough, hemoptysis, chest pain, hilar densities in parenchyma peribronchovascular, and septal pattern with pleural effusion on CT
May need systemic chemo if progessed disease, endobronchial obstruction need laser resection/stent plcement/ radiation therapy |
| What is AIDS-related lymphoma? | Pt with + HIV have high cancer risk, 25-40% malignancy, 10% NHL (but declined with ART)
Could be systemic NHL (>80%), primary CNS lymphoma (15%) or primary effusion lymphoma (5%)
Most common NHL: Burkitt (20%), diffuse large B cell (75%), Plasmablastic, T cell, indolent B cell |
| How is incidence of lung cancer in pt with HIV? | x2/ x4 than non-HIV pt, younger age for cancer |
| What is lymphoid interstitial pneumonitis in HIV? | Infiltrate of interstitium and alveolar spaces of lymphocytes.
25-40% of children with perinatal HIV, second/third year of life
Less common in adults (with ART)
Dx: biopsy, usually benign, B cell polyclonal
Pt approach acc to severity, either ART (symptomatic), glucocorticoids may be effective as well |
| What is pulmonary arterial hypertension? | 0.5% of HIV pt (100 times more than pt with no HIV)
Dx exclusion and conformation and confirmed HIV
cannot distinguish different causes |
