Lec46 Opportunistic Infections Flashcards
What are opportunistic pathogens?
- lack intrinsic virulence
- almost exclusively cause disease in individual with impaired host defense
What are principal pathogens?
- have intrinsic virulence and cause regular disease in pts immunocompetent
- occur with more frequency/severity in pts with impaired host defense
What are you at more risk for with defect in cell mediated immunity?
viral pathogens
What are you at more risk for with defect in neutrophils?
bacterial and fungal infections
How do you measure severity of neutropenia?
absolute neutrophil count
= WBC * (%neutrophils + %bands)
How do you restore immune function in neutropenic pt?
- use GCSF or other growth factor
What are four different stains used for pneumocystis and what do they stain?
GMS stain: cyst forms in bronchioalveolar lavage
Wright-Giemsa stain: stains trophic forms in foamy exudate
Calcofluor white: stains fungal cyst wall
DFA: shows cysts sand trophic forms
What are two diseases to look out for in pt with CD4 < 50?
- disseminated mycobacterium avium complex
- cytomegalovirus
When does HIV pt start to have high risk of PCP pneumonia?
at CD4 < 200
Pt with low CD4 and hypoxemia what should you think?
PCP pneumonia
What stain to find mycobacterium avium complex?
AFB stain
What are symptoms of MAC?
disseminated diseased in AIDS characterized by: bacteremia, fever/chills/sweat/weight loos/diarrhe, bone marrow suppress [anemia, low WBC]
How do you diagnose MAC?
use of special blood culture bottles and can take wks
How do you prevent MAC [mycobacterium avium complex]? Treat?
prevent: azithromycin prophylaxis
treat: 2-3 drug combo and restoration CD4
Fever/headache then seizure + ring enhancing lesions in brain with AIDS? What should you think?
cerebral toxoplasmosis
Fever/headache then seizure without enhancing lesions in brain with AIDS? What should you think?
cryptococcus neoformans [cryptococcus meningitis]
What are clinical findings of JC virus?
- no disease in immunocompetent
in AIDS: enters through resp tract and latent in kidney, reactivation –> viremia and infection of oligodendrocytes –> demyelinating disease
How is JC virus transmitted?
via respiratory tract
What is treatment for JC virus?
no treatment, poor prognosis
What are characteristics of JC virus?
- polyoma virus, non enveloped dsDNA virus, ubiquitous
What is HIV prophylaxis for pulm TB? when do you give it?
- give isoniazid for 9 mos in pt with latent TB
- at any CD4 count
What is neutropenia definition?
ANC < 500
What is HIV prophylaxis for PCP pneumonia? when do you give?
- TMP/SMX
- give when CD4 < 200
What is HIV prophylaxis for CNS toxoplasmosis? when do you give?
- TMP/SMX
- for pt with seropositive toxoplasma with CD4 < 100
What is HIV prophylaxis for disseminated mycobacterium avium complex? when do you give?
- azithromycin
- when CD4 < 50
What 2 kinds of infections do you see at < 1 month after solid organ transplant?
- bacterial surgical site infection
- nosocomial infections
What kinds of infections do you see at 1-12 month after solid organ transplant?
PCP, CMV/EBV/HSV/VZV, listeria, noardia, toxoplasma, strongyloides, community acquired
What 2 kinds of infections do you see at >6-12 months after solid organ transplant?
- community acquired infections
- EBV
If you are treated for rejection after transplant what happens to risk of diseases?
- reset clock, at risk for the same diseases you were when you first got transplant [bacterial surgical site infection, nosocomial]
What is most common classic opportunistic infection in HIV?
PCP
What is prophylaxis for PCP in solid organ transplant recipient?
- TMP-SMX prophylaxis during period of high immunosuppression
What is prophylaxis for CMV in solid organ transplant recipient?
- prophylaxis: ganciclovir or valgancyclovir x 3-6 mos for all recipient
- preemtion: monitor CMV PCR frequently, if PCR + start ganciclovir and decrease immunosuppression
What is prophylaxis for EBV in solid organ transplant recipient?
- monitor EBV pcr frequently, if + decrease immunosuppression
What is definitiona of neutropenia?
ANC < 500 cells/mm
What are major pathogens associated with neutropenia?
- gram negative bacteria [pseudomonas]
- candida
- aspergillus and other filamentous fungi –> esp with long duration of neutropenia
What do you do with pt with fever and neutropenia following chemo?
- initiate broad spectrum antibiotic with activity against pseudomonas [ex cefepime]
- also can add: vancomycin for MRSA, aminolgycoside for gram neg, fluconazole for candida
- if prolonged neutropenia –> give voriconazole in case of aspergillus
What are risk factors for infection following bone marrow transplant?
- neutropenia in pre-engraftment period –> get bacteria/fungi
- immunosuppressants to prevent graft vs host –> see pathogens similar to those after solid organ transplant
What are possible causes of hematuria in pt with acute myeloid leukemia on treatment? [2 viruses]
- due to radiation therapy, chemotherapy
- due to infection: adenovirus, BK virus
What are characteristics of BK virus?
- ubiquitous, polyoma virus
What are clinical syndromes associated with BK virus?
- hemorrhagic cystitis following BMT
- hemorrhagic cystitis and renal graft loss following kidney transplant
What treatment for BK virus?
- no effective therapy, can use cidofovir
- critical to decrease immunosuppression
what are differences nocardia and actinomyces?
both: gram + rods, branching filamentous, slow-growing
nocardia: strictly aerobic, weak acid fast
actinomyces: facultative anaerobic, not acid fast
Toxoplasma transmission?
- parasite, host in nature is cats
- humans infected by cat stool –> contaminated by pet cat fecal oral, or via cow/pig meat that can be infected
What type of infections common in person with antibody deficiencies [ex hypogammaglobulinemia]?
- recurrent serious bacterial infections
- chronic enteroviral infections
- chronic diarrhea
what types of infections common in person with disorder of phagocytic function [chronic granulomatous disease]?
- s. aureus, burkholderia cepacia, nocardia candida, aspergillus
what type of infection occurs in person with T cell lymphocyte deficiency [SCID]?
- PCP
what type of infection occurs in person with hyper IgE?
recurrent severe Staph Aureus infections
what type of infection occurs in person with terminal complement deficiency?
recurrent neisseria meningitidis infection
