Infectious Disease 2 Flashcards
Bacteria characteristics
single celled
well defined walls
no true nuclear membrane
grow independently but require nourishing medium to maintain fxn
Bacteria classification
shape
- spherical = cocci
- rod = bacilli
- spiral = spirilla or spirochetes
response to staining
motility
capsulation
capacity to form spores
aerobic or anaerobic
Pathogenic effects of Bacteria (how do they harm?)
bacteria multiply and compete with host cells for essential nutrients
may directly harm human cells by releasing toxic substances
may cause an immune response that will damage human tissues along with the bacteria
not all bacteria is harmful
Bacterial infections examples
Enterobacteriaceae
C diff
staph
strep
clostridial myonecrosis
pseudomonas
Clostridiomes (clostridium) Difficle (CDI) or C. Diff
diarrhea after antibiotic consumption
GI system
transmission of C. diff is through fecal-oral route (poopy hands to another person who then eats)
Staphylococcal infections
People with chronic skin lesions and surgical and burn patients
Infections of burns, surgical wounds, bacterial arthritis, food positioning
Integumentary system
Streptococcal infections
strep throat
multiple versions target different organ systems
- Groups A; respiratory droplets
- Group B (GBS) - neonatal pneumonia, meningitis, and sepsis
Clostridial Myonecrosis (GAS Gangrene)
Types
Gangrene is death of body tissue usually associated with loss of vascular supply abd then bacterial invasion and putrefaction
3 types; dry, moist and gas
anaerobic conditions
integumentary system
What causes dry, moist and gas gangrene
dry and moist - loss of blood circulation due to various causes
gas - occurs in wounds infected by anaerobic bacteria, leading to gas production and tissue breakdown
Pseudomonas
most common in hospital and nursing home - acquired pathogens
integumentary, circulatory and respiratory systems
How do you select an antibacterial drug?
broad-spectrum (when pathogen is unknown) vs specific agents
other factors such as patient tolerance, bacterial resistance, and doctor preference
Bactericidal vs Bacteriostatic activity
Bactericidal - drugs that kill or destroy bacteria
Bacteriostatic - drugs that do not kill but limit the growth and proliferation of bacteria
classification may depend on drug dosage
Describe the basic mechanisms of antibacterial drugs
- inhibition of bacterial cell wall synthesis and function
- inhibition of bacterial protein synthesis
- inhibition of bacterial DNA/RNA synthesis and function
How do antibacterial drugs cause inhibition of bacteria cell wall synthesis?
Bacteria have a rigid and firm cell wall made of peptidoglycans
Antibacterial drugs can cause inadequate production of peptidoglycans or other structural components of the wall
some drugs punch holes in the cell membrane, destroying selective permeability
some drugs act as DETERGENTS that break apart phospholipid bilayer, creating gaps and leakage
Antibacterial drugs inhibiting bacterial protein synthesis
antibacterial drugs enter and bind to ribosomal subunits of bacteria
binding blocks protein synthesis or causes mis reading
Antibacterial inhibition of RNA/DNA synthesis
FOLIC acid serves as an enzymatic cofactor in several reactions, including the synthesis of bacterial nucleic acids and certain essential amino acids
drugs inhibit bacterial nucleic acid synthesis by inhabiting the production of folic acid
How does resistance to antibacterial drugs occur?
certain bacterial strains have a natural or acquired defense mechanism against specific anti-bacterial drugs, which enables the strain to survive the effects of the drug and continue to grow and reproduce similar resistant strains, representing a gene etic selection process in which only the resistant strain survives
How do we control the problem of bacterial resistance?
antibiotic stewardship (used carefully and not overused)
identify specific pathogenic bacteria and administer selective agents over broad agents to kill resistant strains more effectively
Common side effects of antibacterial drugs
hypersensitivty reactions (skin rashes, itching, wheezing)
GI problems
can interrupt therapy
Virus characteristics
subcellular organisms made up of only an RNA or DNA nucleus covered with proteins
smallest known organisms
completely dependent on host cells to replicate
not susceptible to antibiotics
antiviral meds can moderate the course of the viral illness