Ch. 12 mechanisms of infectious disease Flashcards
host
any orginism capable of supporting the nutritional and physical growth requirements of another organism
infectious disease
the disease state brought about by the interaction with another organism
colonization
the presence and multiplication of a living organism on or within the host
microflora
bacteria inhabiting exposed surfaces of the body
virulence
the disease-inducing potential
pathogens
microorganism so virulent that they are rarely found in the absence of disease
saprophytes
free-living organisms obtaining their growth from dead or decaying organic material from the environment
mutualism
an interactino in which the microorganism and the host both derive benefits from the interaction
commensalism
an interaction in which colonizing bacteria acquire nutritional needs and shelter but the host body not affected
parastatic relationship
only the infecting organism benefits from the relationship
Agents of infectious disease
- Prions
- viruses
- bacteria
- rickettsiaceae
- chlamydiaceae
- fungi (eukaryotes)
- parasites
prions
- protein particles with no nucleic acid or genome
- produces transmissible neurodegeneratice diseases such as creutzfeldt-jacob Disease
Virus
- small pathogens
- no organized cellular structure
- consists of protein coat surrounding a nucleic acid core of DNA or RNA
- they are incapable of replication outside a living cell
- they use other cells to hide within or replicate
Microorganisms
-eukaryotes (fungi)
+membrane-bound nucleus
-Prokaryotes (bacteria)
+the nucleus is not seperated
classification of bacteria
-microscopic: rod, round
-stating of the cell:
+gram-positive organisms: purple by crystal violet
+gram-negative: counter stained by safranin
parasites
-types: protozoa, helminths, arthropods
-method of infecting:
+ infect and cause dissease on other animal
+animals then transmit it to the humans
Rickettsiaceae, anaplasmataceae, chlamydiaceae, coxiella
- organisms that combine the chracteristis of viral and bacterial agents to produce disease in humans
- like virus’, they are dependent on host cells
-has rigid peptidoglycan cell wall like bacteria
+they produce asexually by cellular division
+they contain RNA and DNA similar to the bacteria
classification of infectious disease
- incidence
- portal of entry
- source
- symptoms
- disease course
- site of infection
- virulence factors
epidemiology:
the study of factors, event, and circumstances that influence the transmission of infectious disease among humans
incidence
the number of new cases of an infectious disease that occur within a defines population
prevalence
number of active cases at any given time
incidence of disease
- endemic disease: found in a particular geoprapphic region
- epidemic: abrupt and unexpected increase in the incidence of disease over endemic rates
- pandemic: spread of disease beyond continental boundaries
portals of entry
- penetration
- direct contact
- ingestion
- inhalation
source of an infectious disease
-location:
+nosocomial: developed in hospitalized pts.
+community acquired: acquired outside of health care facilities
-host: an object substamced from which the infectious agent was acquired (may be endogenous or exogenous)
symptomatology
- specific: reflects the site of infection (diarrhea, rash, convulsion, hemorrhagempneumonia)
- nonspecific: can be shared by a number of diverse infectious disease (symptoms such as fever, myalgia, headache)
- obvious: predictable patters (chickenpox, measles)
- covert: may require laboratory testing to detect (hepatits or increase white blood cell count)
disease course in infection
- incubation period
- prodormal stage
- acute stage
- convalescent stage
- resolution stage
factors influencing the site of an infectious disease
- type of pathogen
- portal of entry
- competence of the host’s immunologic defense system
type of antimicrobial agents
- antibacterial agents
- antiviral agents
- antifungal agents
- antiparasitic agents
drug resistance
-bacterial resistance mechanisms: \+inactivate antibiotics \+genetically alter antibiotic binding sites \+bypass antibiotic activity \+changes in the bacterial cell wall
-antiviral resistance mechanisms
+nuceoloside analogs
+protease inhibitors
intravenous immunoglobulin and cytokine therapy
- supplementing or stimulating the host’s immune response so that the spread of a pathogen is limited or reversed
- pathogen-specific antibodies given to the patient as an infusion to facilitate neutralization, phagocytosis, and clearance of infectious agents above and beyond the capabilities of the diseased host
criteria for diagnosis of an infectious disease
+the recovery of a probably pathogen or evidence of its presence from the infected sites of a disease host
+accurate documentation of clinical signs an symptoms compatible with an infectious process
technique for laboratory diagnosis of an infectious agent
- culture
- serology or detection of characteristic antigens
- genomic sequences or metabolites produced by the pathogen
categories of virulence factors
- toxins
- adhesion factors
- evasive factors
- invasive factors
nonpharmacological intervention
-surgical interventions
+providing access to an infected site by antimicrobial agents (drainage of an abscess)
+cleaning of the sire (debridement)
+removing infected organs or tissie (appendectomy)
antibiotic mechanisms
- interference with a specific step in bacterial cell wall synthesis
- inhibition of bacterial protein synthesis
- interruption of bacterial nucleic acid synthesis
- interference with normal bacterial metabolism
classification of antibiotic action
- bactericidal: if it causes irreversible and lethal damage to the bacterial pathogen
- bacteriostatic: if its inhibitory effects on bacterial growth are reversed are reversed when the agent is eliminated
classification and target site of antibacterial agents
- penicillins= cell wall
- cephalosprins=cell wall
- monobactams=cellwall
- aminoglycosides= ribosomes
- tetracyclines=ribosomes
- macroslides=ribosomes
- sulfonamides=folic acis synthesis
- glycopeptides=ribosomes
- quinolones=DNA synthesis
weapons of bioterrorism
-category A agents:
+plague, tularemia, smallpox, hemorrhagic fever viruses
-category B agents: \+agenst of food-borne and water-borne diseases \+agents of zoonotic infections \+ciral encephalitides \+toxins from castor bean
-category C agents \+myobacterium tuberculosis \+nipah virus and hantavirus \+tick-borne and yellow fever viruses \+cryptosporidium parvum
