assignment #1 - Infection Flashcards
4 major portals of entry for infection
- penetration
- direct contact
- ingestion
- inhalation
Penetration as a portal of entry for infection
when body’s barrier is broken (mucous membranes or skin) possibility of microorganisms entering ex. breaks causing injury such as burns, abrasions, surgery or catheterazation
Direct contact as a portal of entry for infection
A few pathogens are transmitted directly from infected tissue/secretions to exposed intact mucous membranes ex. STI’s from intimate contact
Ingestion as a portal of entry for infection
entry of microorganims through oral cavity & gastrointestinal tract ex. many bacterial, viral & parasitic infections such as cholera, dysentry, food poising
Inhalation as a portal of entry for infection
Breathing in pathogenic material into respiratory tract
respiratory tract has many defenses for pathogens entering
- respiratory tree covered in mucus, gets swept away from lungs to mouth by beating motion of cilliated epithelial cells
- coughing
- respiratory secretions have antibodies & enzymes (can inactivate pathogen)
Stages of Disease course
- Incubation period
- prodromal stage
- acute stage
- convalescent stage
- resolution stage
Incubation period of disease course
-pathogens begin active replication though not producing any recognizable symptoms
prodromal stage of disease coure
-first symptoms appear
acute stage of disease course
host experiences maximum impact
convalescent period of disease course
infection contained –progressive elimination of pathogen
resolution stage of disease course
- total elimination of pathogen
- no residual signs or symptoms of disease
subclinical/subacute illness goes through disease process from infection to resolution without
clinically apparent symptoms
Local manifestations of infection
- diarrhea
- rash
- convulsions
- hemmorhage
- pneumonia
systemic manifestations of infection
- fever
- myalgia (pain in muscles)
- headache
- lethargy
Antibacterial drugs
-antibiotics, cause irreversible & deadly damage to the bacteria pathogen
Four basic mechanisms of antibiotic actions are
- interference with specific step in bacterial cell wall synthesis
- inhibition of bacterial protein synthesis
- interruption of nucleic acid synthesis
- interference with normal metabolism
3 primary laboratory techniques for definitive diagnosis
- culture
- serology
- DNA & RNA sequencing
Culture
- growing of microorganism’s outside of the body
- specimen grows on agar plate till microorganism’s grow till detectable
Serology
- identity of infectious agents by measuring serum antibodies in diseased host
- tentative diagnosis can be made if antibody level (antibody titre) rises during acute phase of disease & falls during convalescent period
- not as accurate as culture
DNA & RNA sequencing
-identifying infectious agents through detection of DNA or RNA sequences that are unique to a single agent
Antiviral drugs
-mainly target the viral RNA or DNA of pathogens. Their aim is to inhibit replication of the virus or to inhibit viral enzyme activity (microbe =viruses)
