CIC exam

CIC exam Chain of Infection - 1)Infectious agent= organism with ability to cause disease; greater virulence, invasiveness, and pathogenicity = increased odds of infection 2) Reservoir: place where microbes can persist and reproduce 3) Portal of Exit: way for microbe to leave the reservoir 4) Mode of transmission: method of microbe transfer from one place to another 5) Portal of entry: opening that allows microbe to enter host 6) Susceptible host: Lacks immunity or physical resistance to prevent invasion by microbe Is a circle; each link must be present in sequential order for infection to occur Virulence - Measure of microbe's ability to invade and create disease Depends on ability to: Survive in environment between hosts Transmit between hosts (moving; adherence) Proliferate IgM - Pentamer; primary response, short-lived (6 months); best at fixing complement IgG - Monomer; main blood antibody, secondary response; longer lived. opsonization and toxin neutralization. 4 subclasses Physical barriers - Skin; fever; secreted antimicrobials; innate immunity Complement system - 11=protein cascade; classically activate by ab:ag complexes; alternate by pathogen surfaces Skin defects; examples and associated pathogens - Wounds, burns, trauma, serious derm problems, indwelling devices, injections. Skin flora- S. aureus, CNS, strep pyo, corynebacteria, malassezia furfur Mucous membrane barrier defects; examples and associated pathogens - chemo-induced mucositosis, head/neck trauma, smoking, inhalational injury, antacids/PPIs. Resident flora- anaerobes, aerobic GNR, candida, enteroccus, bovis Body passage obstruction; examples and associated pathogens - Tumors, foreign bodies, stones, cystic fibrosis. Resident flora overgrow or invade; site-specific. Abnormal number or function of granulocytes - Leukemia, chemo, congenital disorders, diabetes. If short term ( 2 wks) then aerobic GNR, Sa, CoNS. IF long term, add fungi (candida, t. glabrata, aspergillus) Abnormalities of cell-mediated immunity - BMT, HIV, steroids, malnutrition, 3rd tri pregnancy. Bacteria: Intracellular pathogens (listeria, salmonella, mycobacteria, nocardia, legionella). Fungi: candida, Cryptococcus, coccidioides, histoplasma. Virus: Herpes group Also toxoplasma and strongyloides. abnormalities of humoral immunity - BMT, HIV, some cancers, aging. Strep pneumo, encapsulated H. flu, Neisseria meningitidis Preventing infection for immunocompromised patients - Take thorough patient history. Prepare before starting with all vaccines, procedures, line placement, screening. Support gastric acidity. Prevent exposures with awesome hygiene, approp food and water precautions, visitor education, no flowers or plants, and possible abx prophy (for infections that might reactivate or high-risk for pneumocystis) Mycoplasma spp. - No cell wall -- limited abx choices. Cause atypical pneumonia. Usually diagnosed by serology Chlamydiae - obligate intracellular parasites. Elementary body=infectious, reticulated= intracellular. DFA or ELISA for detection of antigen is most common. Can also detect antibodies. Rickettsiae - obligate intracellular parasites. arthropod vectors. Rarely culturing; detected by serology using ELISA for antibodies. Textbook viral replication cycle - 1. Attachment 2. penetration/entry 3. replication 4. maturation/assembly 5. release Sensitivity - % of true + who test +; inherent to test Specificity - % of true neg who test neg; inherent to test PPV - Likelihood that a + test represents a true case (% T+/all+); depends on the test and on prevalence of disease in population NPV - Likelihood that a negative test result is a true non-case (%TN/allN); depends on test and population prevalence CSF analysis- bacterial mening - WBCs, mostly PMNs. Increased pressure. Increased protein . Decreased glucose. Bacteria seen on smears. CSF analysis- viral mening - Pressure, glucose normal. Lymphocytes seen, but few WBC in general. Protein normal-elevated. Nothing on smears. CSF analysis- fungus mening - Pressure variable. Glucose low, protein high. WBCs vary, but lymphocytes predominate. India ink smear +. CSF analysis- TB mening - Pressure variable. Glucose low to megalow. WBCs vary, mostly lymphocytes. Protein elevated. AFB stain + Cold Agglutinins test - Used to detect antibodies for Mycoplasma pneumoniae or mononucleosis. Positive test is high titer, with resp Sx indicates M. pneumo infection, viral pneumo, or primary atypical pneumo CRP test - Serum sample looking for the CR protein; normal value is none or low CRP. Indicates current acute inflammation