Staphlylococcus aureus - infections in practice Flashcards
Microbiology of S.aureus
- Gram positive
- spherical, non-motile bacterium
- size: circa 1um in diameter
- yellow/golden colour - aureus=gold
- colonises skin, nasal passages and GIT
- Normal human flora, but can cause suppurative (pus-forming) infections
- Transmission: air borne, human contact, infected surfaces
- PVL-associated S.aureus
Growth of Staphylococcus aureus
- aerobic respiration or facultative anaerobe
- binary cell division reproduction
- staphylococcus - “bunch of grapes” - shape
Produces
-coagulase - used as a marker, also a virulence factor that confers resistance to phagocytosis
MRSA
Meticillin-resistant Staphylococcus aureus
MSSA
Meticillin-sensitive Staphylococcus aureus
Resistance
Strains of Staph a. emerging resistant to meticillin and related beta-lactams
MRSA also resistant to other antimicrobials
HA-MRSA
Patients groups affected
Hospital-acquired MRSA
->60s
-some contract infection after hospital admission and procedures (HAIs)
-immunocompromised, dialysis patients
-patients undergoing invasive medical procedures
-infection sources are colonised assymptomatic patients
Transmission
-healthcare providers
-patients
CA-MRSA
patient groups affected
- Community-acquired MRSA
- younger, otherwise healthy patients
Transmission:
- patient already colonised
- events (trauma/cuts) leads to soft tissue and skin infections
- spread within patient faster
- strains more virulent
- may lead to more severe illness
3 types of S.aureus infection
Skin
- mucosal membrane infections
- pimples, boils
- leg ulcers
- pressure sores
- cellulitis
- wound infection
- slapped cheek syndrome
- necrotising fasciitis (rare)
Invasive
- Surgical wound infection
- UTIs
- septicaemia
- pneumonia, endocarditis
- osteomyletis
- septic arthritis
- menginitis
Other
- Food poisoning
- Toxic Shock Syndrome (TSS)
Conjunctivitis
Causes
Who does it affect?
S.aureus - chronic/recurrent cases Also -Streptococci -chlamydia -gonorrhoea -viruses -allergic conjunctivitis Affects -young, old, diabetes, immunocompromised
Conjunctivitis symptoms+signs
- grittiness
- itching
- discharge
- pink eye
Conjunctivitis complications
- scarring
- secondary systemic infection
Conjunctivitis treatment
- self limiting within 1-2 weeks
- chloramphenicol drops -2hourly/QDS
- chloramphenicol ointment QDS
- fusidic acid gel - BD
Pharmacist’s role and public health role in Conjunctivitis
Role -OTC sales of chloramphenicol -POM to P switch -PGD - Chloramphenicol/fusidic acid in minor ailment scheme or pharmacy first scheme Public health role -regular hand washing/drying -good eye care, no contact lens use -towels/pillows/make-up applicators - beware! -HPA factsheet on conjunctivitis
Impetigo
1) Causes
2) Types
3) Epidemiology
1) Staphylococcus aureus, Streptococcus pneumoniae
2) Primary - infection caused by infecting a cut/bite/graze
Secondary - where an underlying skin condition exist
3) Summer months
- Teenagers, children, diabetics, immunocompromised
- schools, nurseries, army barracks, contact sports
Signs and symptoms of impetigo
- bullous - affecting trunk, arms legs with large blisters
- non-bullous - accounts for 70% of infections, itchy sores with yellow-brown crusts around nose and mouth
Complications of impetigo
- lymphangitis
- cellulitis
- guttate psoriasis
- scarlet fever
- septicaemia
Treatments for impetigo
-self limiting within 2-3 weeks
-fuscidic acid cream TDS/QDS
-Mupirocin ointment TDS (MRSA)
-Oral flucloxacillin QDS
-Oral eryhtromycin QDS
(antibiotic doses above are as per BNF)
Pharmacist’s role and public health role in impetigo
Role
- differential diagnosis
- GP referral
- PGD - minor ailment scheme
Public health Role
- regular hand washing before/after treating
- short nails
- towels washed and food preparation
- school nursery isolation, broken skin condition
- HPA advice
Device-related infections
causes
epidemiology
S.aureus (including MRS) introduced to the body via surgical opening
-surgical patients, hospitalised patients with IV lines
patients in community with long-term IV or urinary catheter, chemotherapy patients
Devices at risk of MRSA
- vascular or urinary catheters
- tracheostomy tubes
- feeding tubes
- CNS shunts
- orthopaedic implants
Signs and symptoms of device-related infections
- redness, warmth, inflammation and pain at site
- exudate at site
- fever, malaise
- tachycardia
Complications of device-related infections
- endocarditis
- septicaemia
Treatment of device-related infection
-removal of temporary device
-sometimes removal of infected tissue
IV antiboitic: 7-10 day course
-Flucloxacillin
-clarithromycin
-vancomycin
-rifampicin
-clindamycin
-linezolid
Pharmacist roles in device-related infection
- Infection control training for patients, carers, pharmacy staff, care home staff
- counselling patients on prevention therapy/pre-screening
- wards - patient identification and isolation - gloves and aprons when with MRSA infected/colonised patients
pharmacist public health role in device-related infection
- -hand washing policies and audit of these
- strict sterile technique
- sterile cleaning suppies
- MRSA leaflets and public health campaigns
Summary of S.aeurus
- numerous and resistant strains make it more difficult to combat
- commonly carried in nose and skin
- multiple transmission methods and virulence factors
- multiple infection sites in body
- numerous medical conditions with varying degrees of severity
