E:2.1 Flashcards
What do skin and skin structure infections (SSSIs) infect?
Epidermis, dermis, or subcutaneous tissue
What are the most common pathogens in SSSIs?
S. aureus and S. pyogenes (GAS)
What does ABSSSI stand for?
Acute bacterial skin and skin structure infections
What is an uncomplicated SSSI?
An SSSI that is localized and confined to the epidermis and dermis layers
What is a complicated SSSI?
Infection of deeper skin structures
Impetigo/ecthyma pathogens
S. aureus* (*most common) S. pyogenes
Folliculitis pathogens
S. aureus*, P. aeruginosa
Carbuncle, Furuncle pathogens
S. aureus* including CA-MRSA, CA-MRSA causes spider bite like lesions
Uncomplicated abscess pathogen
S. aureus
Cellulitis pathogens
Beta-hemolytic streptococci, S. aureus
Erysipelas pathogen (dermatologic)
S. pyogenes (Group A strep)
Complicated cellulitis pathogen
S. pyogenes*
Complicated abscess pathogen
S. aureus
Erysipelas pathogen (soft tissue)
S. pyogenes*, S. aureus
Necrotizing fasciitis pathogens
S. pyogenes, Vibrio vulnificus, Aeromonas hydrophilia
Infected bites pathogens
Eikenella, Pasteurella, oral anaerobes
Infected burn pathogens
Staph/Strep, P. aeruginosa
Gangrene pathogens
C. perfringens, anaerobes
Impetigo/Ecthyma
It is most common is children. It causes crusty skin.
Impetigo contagiosa
Caused by S. pyogenes; most common in children; contagious disease
Bullous impetigo
Purulent and is caused by S. aureus
Ecthyma
A deep form of impetigo with deeper erosions of the skin into the dermis
Folliculitis
infection of hair follicles.
caused by S. aureus* and P. aeruginosa (under chlorinated hot tubs)
Furunculosis
Boils that are singular swollen skin infection of the hair follicle
Cabunculosis
Cluster of boils that are highly swollen follicular masses
Abscesses
Collections of pus.
Common SSSI in IV drug users (watch for MRSA)
Pathogen is S. aureus
Cellulitis
Inflammation of connective tissue that is common in elderly patients.
Caused by Beta-hemolytic streptococci and S. aureus
Erysipelas (St. Anthony’s fire)
Cellulitis of skin involving blockage of lymphatics, common in elderly patients
Caused by S. pyogenes (Beta-hemolytic, Group A strep)>S. aureus
Infected Bites
Human bite=Eikenella, oral anaerobes
Cats/Dogs= Pasteurella multocida, oral anaerobes
Cellulitis at site of bite
Necrotizing Fasciitis
“Flesh eating” pathogens- S. pyogenes (GAS)*
Vibrio vulnificus and Aeromonas hydrophilia are usually waterborne infections due to traumatic wound injury and preexisting open wounds
Burn wound infections
Often caused by Staph/Strep and P. aeruginosa (Silver sulfadiazine/Silvadene covers)
Why do diabetes patients have a high rate of foot infections?
- Loss of pain sensation (neuropathy)
- Reduced blood circulation (ischemia)
- Decrease neutrophil immunity
- Weakened tissues
Diabetic Foot infections
Non-healing ulcers and foul-smelling odor (fermenting anaerobes present)
Pathogens- polymicrobial
Pressure Sores (Bedsores)
Occur in any location of body receiving inadequate oxygenated blood supply (ischemia). The ischemia leads to tissue damage and necrosis.
Wounds can be infected by skin flora (Gram+ cocci)
Joint and Bone Infections origins
Joint infections (septic arthritis) and Bone infections (osteomyelitis) Both infection types may either be hematogenous (blood) or contiguous (adjoining infected tissue) origin
Joint and Bone infection most common pathogens
S. aureus and coagulase negative staph (S. epidermidis)
What can osteomyelitis result in?
Necrosis and bone death
Where can osteomyelitis infection originate from
Either the bloodstream (hematogenous) or from adjoining soft tissue (contiguous)
Pathogens that can cause osteomyelitis
S. aureus and coagulase negative staphylococci account for most infections.
S. aureus and Pseudomonas can come from IV drug use. S. aureus can come from orthopedic hardware.
Nail thru sneaker (Pseudomonas), Human Bite (Eikenella), Animal Bite (Pasteurella)
Hematogenous Osteomyelitis
Bone is seeded by bacteria from infection elsewhere in the body.
Common in acute long bone osteomyelitis in kids and vertebral osteomyelitis in adults.
Vertebral osteomyelitis often arises from other infections.
Gram negative enterics may spread from bladder
Contiguous osteomyelitis
Bone seeded by bacteria from adjacent infected site
Common consequence of DFI, open fractures, and surgical procedures
Arthritis
Inflammatory process that involves the joint(s)
Septic arthritis
bacterial infection of joint that causes inflammation
Arthralgia
Refers to pain that involves the joint
Septic arthritis Origins
Most cases are due to hematogenous seeding from an infection elsewhere in the body
What response causes the inflammation in septic arthritis?
Neutrophils/Macrophages will enter infected joint and release cytokines that cause inflammation.
Most common pathogen in Septic Arthritis
S. aureus
Acute monoarticular arthritis
Usually involves 1 joint
S. aureus
N. gonorrhoeae in young adults
Polyarticular arthritis
Disseminated Neisseria infection
Monoarticular Infectious Arthritis
Septic arthritis occurs most often in large joints
S. aureus/MRSA most common in adults
Gonococcal arthritis in young adults
S. aureus/MRSA and P. aeruginosa in IV drug users
Hardware-Associated Septic Arthritis
Prosthetic joint infections
Can come from surgery
Is caused by coagulase-negative staph (S. epidermidis)
Hallmark of prosthetic joint infections and how to prevent
Biofilm formation often with Staphylococcus epidermidis. This allows biofilm bacteria to adhere to implant. Biofilm is good at preventing antimicrobial penetration, but Rifampicin and Clindamycin are good at penetrating
Reactive (Reiter’s Arthritis)
It is an autoimmune response.
Caused by C. trachomatis and Campylobacter
Often in sexually active young adults
Check pt. for genetic marker HLA-B27 (common in Reiter’s pts.)
Lyme Arthritis
Tick-borne Lyme Disease
Pathogen: Borrelia burgdorferi*
