AGENTS OF BONE MARROW INFECTION Flashcards
what is Osteomyelitis?
An infection of the bone and bone marrow
how does osteomyelitis occur?
when bacteria are introduced to the bone tissue in the following manners: as an extension of a local soft-
tissue, urogenital, or respiratory-tract injury; carried via the bloodstream; surgery; an open
fracture; or intravenous drug use.
What is the most causative agent of osteomyelitis?
Staphylococcus aureus because it resides in the body and on the skin as normal flora and is
pathogenic when traumatically introduced into other tissues and the bloodstream
what is the most common bacterial species to cause osteomyelitis in sickle cell patients?
Salmonella species
what does Salmonella osteomyelitis involve?
the diaphysis, or shaft, of the long bones in
children
how does brucella species cause brucelliosis/osteomyelitis?
can infect humans via ingesting
undercooked meat or unpasteurized dairy, inhaling the bacteria, or traumatic entrance through the
skin and mucous membranes via injury
how does group B strep cause osteomyelitis?
seen in newborns who acquire
an infection from their mother during birth
how does group A strep (progenies) cause osteomyelitis?
Newborns and children may develop bone marrow
infections
what are the virulence factors of Brucella species?
not encapsulated,
they possess an antigenic
lipopolysaccharide outer surface. O-antigens on the surface of the organism allow for the bacteria
to invade and enter host cells for replication and survival. Complement does not easily bind to the surface of lipopolysaccharides, providing the bacteria the ability to evade host immune responses and proliferate.
ability to survive extreme temperatures and pH levels, allowing it to thrive in various parts of the body
and allowing infections to spread
what are sickle cell disease patients susceptible to with a Salmonella infection?
susceptible to
sepsis and osteomyelitis infections
what antigens aid in Salmonella species to adhere to its host?
Fimbriae and H antigens on the
outer surface of the bacteria
surface proteins and antigens including antiphagocytic proteins, capsular antigens, H flagellate antigens, and
immunogenic O antigens, prevent phagocytosis and complement-mediated lysis of bacterial cells.
Lipid A in the outer layer is released upon the death of the
bacterial cell and is the endotoxin responsible for the fever and shock associated with these
infections
what contributes to the virulence of S. aureus?
the organism’s rigid peptidoglycan cell wall and surface
capsular antigens
which inhibit phagocytosis and promote adherence to host cells.
what is the importance of techoic acids in the cytoplasm membrane and cell wall of S. aureus?
they promote adhesion, colonization, and
bacterial cell division in hosts
How does S. aureus evade phagocytosis?
Protein A facilitates biofilm formation and adhesion, and it binds to
receptors on host immunoglobulins
Fibronectin-binding
proteins present in methicillin-resistant bacteria strains also promote the formation of:
a biofilm,
which is described as a thin, slimy film of bacteria that adheres to the surface of host cells and
tissues