Med-Surg: Chapter 21: Methicillin-Resistant Staphylococcus aureus (MRSA) Flashcards
Staphylococcus aureus (S. aureus)
- asymptomatic pathogen
- normal bacterial flora of humans
- colonized (the host carries the bacteria without active infection)
- aerobic, gram-positive, non-sporulating (does not make spores capable of reproduction), coagulase-positive bacterium (produces the enzyme coagulase, which helps convert fibrinogen to fibrin)
Where are the individualized colonized with Staphylococcus aureus?
- nose
- throat
- axillae
- toe webs
- perineum
Interventions for the Decline in MRSA rates?
general infection control efforts
- alcohol-based hand rubs
- hand hygiene
- efforts targeted at eliminating bloodstream infections
- enhanced antimicrobial stewardship programs
Methicillin-resistant S. aureus is a result of what?
decades of unnecessary antibiotic use
- community acquired
- hospital acquired
What is Methicillin-resistant S. aureus resistant to?
all beta-lactam antibiotics including penicillin’s, cephalosporins, and carbapenems
Risk Factors for Hospital acquired MRSA? (HAMRSA)
- current/recent hospitalization
- residing in long-term care facility
- invasive procedures/ medical devices (urinary catheters or IV lines that create portal of entry)
- recent antibiotic use
- long-term broad-spectrum antibiotic therapy allowing bacteria to become resistant to a specific antibiotic
- weakened immune system
- comorbid conditions
- dialysis devices
- Gastrointestinal (GI) disorders
Risk Factors for Community acquired MRSA? (CAMRSA)
-less than 2 years of age
-Athletes
-IV drug abusers
-Men who have sex with men
-Military personnel
-Prison inmates
-People living in shelters
>risk factors are associated with close skin-to-skin contact, crowded living conditions, and poor hygiene
Pathophysiology of MRSA
because it is a coagulase bacterium, MRSA is coated with a fibrin wall that resists phagocytosis, making the bacterium more virulent, enabling it to protect itself from host defense mechanisms
-S. aureus destroys the active lactam ring in the penicillin molecule by secreting the enzyme beta-lactamase; this genetic mutation prevents the beta-lactam ring from binding to the bacterial cell thus, the agent cannot exert its antimicrobial effects
Endogenous pathogen
pathogen residing on the body
Exogenous Pathogen
outside the body sources
-the mode of transmission from an exogenous source is contaminated surfaces
Where is MRSA found?
on humans
-can live on surfaces and humans for days to weeks; varying life span
How is MRSA transferred/spread?
can easily be transferred to the skin and other body areas, increasing risk for infection
ex: if a person is colonized with MRSA in the nose and wipes the nose with the hand and then touches an open wound, the bacteria can then be transferred to the wound and cause infection
- contact
- can be spread if an infected person touches the source of infection and then touches an object or surface
- easily spread in hospitals from patient to patient or from body part to body part on the unclean hands of healthcare personnel or improperly cleaned equipment
How to prevent transmission?
- proper hand hygiene
- covering cuts and open wounds with bandages
- bathe and shower regularly
Clinical Manifestations of Staph aureus
- minor skin infections (pimples, abscesses, sties, and impetigo)
- these are clinical manifestations if infected with the bacteria staph aureus
Clinical Manifestations of MRSA: These happen when infected with MRSA infection
- pneumonia
- skin and soft tissue infections
- surgical-site infections
- bloodstream infections
Complications
- resistant to numerous antibiotics; difficult to treat
- can cause widespread infections
- increased morbidity and mortality rate
- septic shock
- osteomyelitis
- untreated can lead to multisystem organ failure and death
Medications to Treat MRSA
- Vancomycin (Vancocin)
- Linezolid (Zyvox)
- Clindamycin (Cleocin) for CAMRSA
- Sulfamethoxazole/Trimethoprim (Bactrim) for CAMRSA
Methicillin-resistant S. Aureus modes of transmission ad how it infects the skin
transmitted via skin contact with a carrier and entering through breaks in the skin
-can be transmitted easily to the skin and other body areas
-transmitted by skin contact with a carrier and contact with contaminated items and surfaces
>MRSA infects the skin by entering minor scrapes or cuts; infection looks like a boil, a pimple, or spider bite; wound is very contagious, filled with the bacteria
-symptoms: swelling, pus/infection, painful, infection slow to heal
Symptoms of MRSA infection
- swelling
- pus/infection
- painful
- slow to heal
Medication: The Trough Level
blood sample drawn after a dose is given but immediately before the next dose
-monitored weekly to avoid toxic doses and maintain therapeutic levels
Medication for MRSA: Vancomycin
antibiotic
- administered IV or orally
- trough levels drawn and monitored weekly to avoid toxic doses and maintain therapeutic levels
- if trough levels high, can cause nephrotoxicity (kidney) and ototoxicity (ear)
- weekly BUN and serum creatinine to assess kidney function b/c of nephrotoxicity
- administer over 1 HOUR to avoid red man syndrome (red face & neck)
- report signs of hypersensitivity, tinnitus, vertigo, or hearing loss
Medications for MRSA: Linezolid
antibiotic
- used to treat skin and soft tissue infections caused by MRSA
- bacteriostatic (stop organism reproduction) against enterococci and staphylococci
- IV or orally
- given for 7 to 21 days depending on infection
- if given for > 10 days, monitor CBC for myelosuppression (anemia, leukopenia, pancytopenia, and thrombocytopenia)
- may cause diarrhea, nausea, and vomiting
- can cause CNS reactions when taken with serotonergic psychiatric medications
- avoid foods high in tyramine (aged cheeses, dried/processes meats, alcohol, soy sauce)
Medications for MRSA: Clindamycin
antibiotics
- treats CAMRSA (community acquired MRSA)
- IV or orally
- can cause diarrhea and C. diff
Medications for MRSA: Sulfamethoxazole-trimethoprim (Bactrim)
antibiotic
- treats CAMRSA (community acquired MRSA) skin and soft tissue infections
- dosing adjusted with impaired renal function
- can cause nausea, vomiting, loss of appetite
- can cause sun-sensitivity (encourage sunscreen)
- report signs of jaundice, somnolence (sleepiness), and confusion (can be a sign of fulminant hepatic necrosis)
- stay hydrated to prevent renal stones while taking this medication
