Nosocomial infections Flashcards
What is the prevalence of hospital acquired infections?
6.4% prevalence in hospital
Significant burden
What are common organisms responsible for HCAIs?
MRSA
MSSA
E. coli
C. difficile
Norovirus, Rotavirus, Sapovirus
VPE
Multi-resistant Gram Negatives
What does MRSA stand for?
Methicillin resistant S. aureus
What does MSSA stand for?
Methicillin sensitive S. aureus
Why are HCAIs so relevant?
Often in the news
Legal firms look for patients who developed HCAIs to seek compensation
Why are HCAIs important?
Estimated cost > £1 bn
Increased mortality and morbidity
Poor patient experiments
Why do HCAIs have such high costs?
Prolonged hospital stays
Further treatments and procedures
What are examples of HCAIs?
Urinary tract infections
Respiratory tract infections
Surgical site infections
Indwelling device infections
In which population are UTIs particularly prevalent?
Elder population
May be urinary catheter-associated
What is a way of diagnosing UTIs?
White blood cells or bacteria in urine sample
Grow bacteria in culture to see what antibiotic used
What are causes of respiratory infections?
May be caused by unusual organisms like Pseudomonas or other gram negative bacteria
May be associated with ventilation - bacteria like to stay in ventilators
What are examples of indwelling devices?
Venous and arterial catheters
Prosthetic joints
Cardiac pacemakers and prosthetic valves
What do infections of indwelling devices cause?
Local infections
Bacteraemia
Sepsis - venous catheter in major arteries or veins can cause wide spread infections
What are examples of multi-resistant gram negatives?
Extended spectrum B-lactamases
Carbapenemase producing Enterobacteriaceae
Multiresistant Pseudomonas spp, and Acinetobacter spp.
Where is MRSA found?
Present in 10-20% of population asymptomatically
Mostly in nose and perineum
What does MRSA cause?
Bacteraemia
SKin and soft tissue infections - indwelling devices
Endocarditis - infection of the heart valves
Osteomyelitis - infection of bones
Are MRSA rates rising or falling?
Falling
What new rule has been implemented regarding MRSA infections?
Trust requires all infections to be reported
How can hospitals lower the rates of MRSA infections?
Screen patients prior to admission/procedures
Which patients are at higher risk of containing MRSA colonies?
Patients that have been in health care setting before
What samples are used to test for MRSA?
From the nose or perineum
How are the samples screened to test for MRSA?
NAAR
Culture with chromogenic media
What is chromogenic media?
Only bacteria that are methicilin resistant can grow on these plates
Will show up pink
Quick and easy
What happens to the patients that are found to be carriers of MRSA?
Body washing with specific soaps or detergents
Antibiotics
Alternative antibiotics required to treat infections caused by MRSA
Which viruses cause diahrrea and vomiting?
Norovirus
Rotavirus
Sapovirus
How many cases of Norovirus are there in the UK per year?
600 000 - 1 000 000 cases annually
Normally self-limiting
What is a characteristic of Norovirus?
More common in winter
What is the significance of Norovirus?
Responsible for outbreaks and closures of hospital wards
Enormous impact on trust
Adds financial burden to the patients
How are Norovirus, Rotavirus, Sapovirus diagnosed?
Clinically by NAAT
Specimen of stool sent to the lab
What is done to patients diagnosed with norovirus/ rotavirus/ sapovirus?
Controlled by isolation of infected patients and other strict infection control
What are examples of infection control?
Hand washing
Barrier nursing - staff wearing gloves and disposable aprons
Restriction of visitors
Where are C. difficile normally found?
Normal biota
GI bacteria - associated with normal microflora
What causes C. difficile to increase in population?
Antibiotics
Confers resistance to C. difficile
Other bacteria that normally competes with the bacteria and keep them in low numbers are killed off
What are the symptoms of C. difficile?
Symptoms range from mild, self-limiting diarrhoea to life-threatening pseudomembranous colitis and toxic megacolon
What is pseudomembranous colitis?
Inflammation of the colon
Occurs in some people who have taken antibiotics
Almost always associated with an overgrowth of the bacteria
What is the treatment of C. difficile infection?
Depends on severity
Removal of contributing agents
Use of anti-C. difficile agents
What are examples anti-C. difficile agents?
Metronidaxole
Vancomycin
Fidaxomicin
How is C. difficile diagnosed?
Assessment of diarrhoea
WBC
Temperature
Evidence of colitis
Evidence of renal impairment
What is used to assess diarrhoea?
Bristol stool chart
Record their stool habits
What is evidence of colitis?
Abdominal tenderness or abnormalities in the abdomen
How is stool tested for C. difficile?
Two stage algorithm
Two of these 3 tests are used:
- Glutamate dehydrogenase by ELISA
- Toxin of C. difficile by ELISA
- Detect the bacterium by NAAT - molecular method
What is ELISA?
Enzyme-linked immunosorbent assay
What is glutamate dehydrogenase?
Produced by organism in the stool sample
Can’t guarantee that C. difficile is creating the toxin
What is the positive test for glutamate dehydrogenase?
Yellow
What are the two main species of VRE seen clinically?
E. faecium
E. faecalis
How do these bacteria obtain resistance?
Many mechanisms
Where are these organisms found?
In the GI tract
What type of organism are VREs?
Low pathogenicity organisms
What do VREs cause?
Opportunistic infections
In patients who are immunocompromised
What are common types of infections caused by VREs?
Indwelling catheters
Intra-abdominal infections post surgery or translocation from gut
Endocarditis
Joint infections
What precautions are taken in hospitals to prevent VREs from causing disease?
Patients are screened
To know if they have the organism in the gut
So they can be given different antibiotics if they develop the infection
What are ways to identify VREs?
Can see hazy growth around vancomycin in antibiotic sensitivity testing
Grow using chromogenic media - purple indicates E. faecium/faecalis
What are ESBLs?
Externded spectrum beta-lactamases
Enzymes expressed by Gram negative organisms
Inactivate penicillin and cephalosporins
What are the main ESBLs which are of biggest concert?
Enterobacteriaceae
Where are Enterobacteriaceae found?
Carried in the GI tract as commensal
What do Enterobacteriaceae cause?
Infections in the same spectrum as other Enterobacteriaceae
What type of infections do Enterobacteriaceae cause?
Surgical meningitis
UTI
Intra-abdominal sepsis
What is a characteristic of ESBLs?
Resistant to large spectrum of
- beta lactam antibiotics
- 3rd generation cephaloporins
What is used to identify ESBLs?
Chromogenic media
NAAT
What type of chromogenic media is used to identify ESBLs?
Media is selective
Antibiotics used that only ESBLs will grow on
Screen for broad set of resistant profiles
What antibiotics are used to treat ESBLs?
Carbapenems
Fluoroquinolones
Aminoglycosides
Temocillin
What are CPEs?
Carbapenemase producing Enterobacteriaceae
Multi-resistant gram negative organisms
Resistant to carbapenem drug family
What type of infections do CPEs cause?
Urinary tract infections
Abdominal sepsis
What type of antibiotics are used to treat CPEs?
Treated with other, less effective or toxic antibiotics
Leave with few antibiotic options
What have public policy schemes done to prevent CPE infection?
Public health england have given guides to screen for, investigate and prevent transmission of these organisms
How are CPEs identified?
Culture or NAAT
What is an example of a culture form to identify CPE?
Modified Hodge test
Describe the modified Hodge test
Control strain that is placed in the agar is sensitive
Test strain obtained from the patient is not resistant to the antibiotics when the zone inhibition is a round shape
If the zone of inhibition has a clover-leaf shape = contains carbopenamase
The resistant genes from the CPE have also been transferred to the E. coli found homogenously in the medium
What controls are taken once a patient has been identified with CPE?
Patients are screened
Give antibiotics that act on the bacteria
Isolate the infected people in rooms
What is done to prevent spread of nosocomial infections?
Each trust has a named individual responsible for Infection Prevention and Control
Government targets are put for the number of MRSA, MSSA, E.coli and C, difficile cases
Screening for key organisms
Rotavirus vaccination
Policies and guidelines for best practice
What happens if trusts breach the governmental targets of nosocomial infections?
Trusts are fined if they breach the targets
What are examples of policies and guidelines for best practice to prevent nosocomial infections?
Hand washing and environmental cleaning
Isolation of patients with infections
Antimicrobial stewardship
What is antimicrobial stewardship?
Use appropriate antibiotics
Not receive antibiotics if they don’t need them
