oportunstic infections Flashcards
what are the opportunistic pathogens?
- -usually benign but have the ability to cause disease in an immunocompromised host (e.g., patients with AIDS or after chemotherapy)
- -Examples of opportunistic infections: oral candidiasis, vaginal yeast infection, cytomegalovirus infection, cryptococcal meningitis, pneumocystis jirovecii pneumonia, toxoplasma encephalitis
opportunistic pathogens have high virulence. True/False
False
of low intrinsic virulence that are not normally harmful: e.g.
– Coagulase-negative staphylococci
– Aspergillusfumigatus
what are the pathogens commonly associated with asplenia and hypogammaglobulinemia
S. pneumoniae
H. Influenzae
what pathogen has increased the risk of causing disease in complement deficiency?
Neisseria spp
impaired cell-mediated immunity increases the risk of what infections?
1) intracellular bacteria (listeria)
2) viruses
3) fungi
4) parasites
what is the immunocompromized state?
A state of reduced activation and/or efficacy of the immune system. Etiologies include congenital immunodeficiency disorders, AIDS, diabetes mellitus, chronic alcoholism, certain neoplasms (e.g., lymphoma), treatment with certain drugs (e.g., corticosteroids, chemotherapeutic agents), and radiation therapy,
what is the general vs specific immunocompromised state?
1)General term
• any patient compromised by virtue of his/her underlying condition
• e.g. multiple trauma patients in ICU
non-specific
2)Specific term
• A patient with a recognized deficiency of one or more immune parameters
• e.g. neutropenic patient on chemotherapy
refers to specific categories of patients
what is the importance of opportunistic infections?
- Increased numbers of immunocompromised patients
- A significant cause of morbidity & mortality
- Can be polymicrobial& complex
- Bacteria often are multi-antibiotic resistant
- Variable clinical presentation – atypical, fever often absent
- May be difficult to diagnose
what are the features of Opportunist Pathogens
i. Low pathogenicity & sometimes ubiquitous, e.g. Pneumocystis jirovecii, Candida albicans, S. epidermidis, P. aeruginosa
ii. They can be part of normal flora, e.g. S. epidermidis, Candida
iii. Adapt to host & circumstances, e.g. biofilm production
iv. Often difficult to completely eradicate / may relapse, e.g. CMV
v. Variable clinical presentation
vi. Absent normal immune response; negative serology
what is the primary immunodeficiency?
Congenital immunodeficiency disorders are characterized by a deficiency, absence, or defect in one or more of the main components of the immune system. These disorders are genetically determined and typically manifest during infancy and childhood as frequent, chronic, or opportunistic infections
what are the causes of primary immunodeficiency?
– Antibody deficiency syndromes
– Neutrophil dysfunction e.g. chronic granulomatous disease
– severe combined immune deficiency (SCID), complement deficiency states
name congential B-cell immunodeficiencies
1) Brutton agammaglobulinemia
2) Selective IgA deficiency
3) Common variable immunodeficiency
what are the congenital T cell immunodeficiencies
- -DiGeorge syndrome
- -Job syndrome (hyper-IgE syndrome)
- -IPEX syndrome
- -IL-12 receptor deficiency
what are the causes of secondary immunodeficiency?
– Immunosuppressive therapy: Steroids, chemotherapy
– Malignancy
– Autoimmune disease: Rheumatoid arthritis
– Microbial infection: HIV
– Biochemical abnormalities: Diabetes mellitus, malnutrition
– Asplenia/hyposplenism
what anatomical abnormalities increase risk with opportunistic pathogens?
1)Barrier problems– intact skin is a key component of the body’s defenses
o e.g. burns
2)Inadequate clearance
o e.g. respiratory tract cilia that are abnormal in structure or function: Primary ciliary dyskinesia
3)Obstruction
o e.g. cystic fibrosis, chronic obstructive pulmonary disease (COPD)
4)Foreign body
o e.g. a central venous catheter
list endogenous bacteria that can cause opportunistic infections
• S. epidermidis • S. aureus • Gut flora –E. coli –Enterococci, including vancomycin-resistant enterococci (VRE)
list exogenous bacteria that can cause opportunistic infections
- S. aureus, including MRSA
- Enterobacteriaceae
- P. aeruginosa
- Listeria
- Atypical mycobacteria &M. tuberculosis
list viruses that can cause opportunistic infections
• Herpesviruses: Latency leading to reactivation
–Herpes simplex virus 1 & 2
–Varicella-zoster virus
–Cytomegalovirus
• Polyomaviruses: Latent in kidney & lymphoid tissue
–JC virusProgressive Multifocal Leukoencephalopathy (PML)
–BK virus(stem cell and renal transplant recipients)
• Parvovirus B19: Can cause profound red cell aplasia
–Persistent infection in immunocompromised/persistent anemia
• Hepatitis B: chronic carriage or reactivation of latent infection
what is the PML (progressive multifocal leukoencephalopathy)
A fatal disease characterized by multifocal demyelination in the brain. Caused by reactivation of a latent JC virus infection in immunosuppressed patients (e.g., AIDS, hematological malignancies, post-transplant period, use of natalizumab).
what is caused by the BK virus?
A non-enveloped, double-stranded circular DNA virus of the polyomavirus family that infects the urothelium. BK virus infection is widespread but asymptomatic in the general population. Reactivation of the virus in immunosuppressed patients (especially transplant recipients) can cause polyomavirus-associated nephropathy and/or polyomavirus-associated hemorrhagic cystitis. The name is derived from the initials of the first kidney transplant patient from which the virus was isolated.
what fungi cause opportunistic infections
• Candida spp. –Mucositis, oesophagitis, candidaemia • Aspergillusfumigatus – Lower respiratory tract infection • Cryptococcus neoformans –Meningitis or meningoencephalitis • Pneumocystis jirovecii –PCP –Pneumonia
list important protozoa that cause opportunistic infections
• Toxoplasma gondii
–Cerebral toxoplasmosis
• Cryptosporidium parvum
–Severe diarrhoea
define neutropenia
A decreased neutrophil count (mild: 1000–1500 cells/μL; moderate: 500–1000 cells/μL; severe: < 500 cells/μ). Most commonly caused by bone marrow damage, which can be drug-induced or due to malignancy or viral infection
neutropenia increases the risk of bloodstream infections (BSI) & respiratory infections. True/False
True Source of microbial invasion of the blood 1)chemotherapy-induced mucositis 2)breaks in the gastrointestinal lining –Bacterial/fungal translocation 3)intravascular lines
