Hospital infections

Question 1

What does antimicrobial mean?

Answer 1

Interferes with growth and reproduction of a microbe

Question 2

What does antibacterial mean?

Answer 2

Commonly used to describe agent to reduce or eliminate harmful bacteria

Question 3

What does antibiotic mean?

Answer 3

Type of microbial used as medicine for humans, animals and are originally developed from naturally occurring compounds

Question 4

What are hospital associated infections (HAI)?

Answer 4

Infections that occur after exposure to healthcare, starting >48 hours after admission to hospital

Question 5

What are the most frequent types of HAI?

Answer 5

Surgical site infections, urinary tract infections, pneumonia, bloodstream infections and gastrointestinal infections

Question 6

What is the burden of HAIs?

Answer 6

Infection results in a large increase in length of stay in hospital and poses an extra cost of 1 billion pounds to the NHS every year

Question 7

What are the sources of infection in hospital?

Answer 7

Intervention: Lines, chemotherapy, catheterisation, prophylactic or inappropriate prescription of antibiotics, intubation and prosthetic material
Dissemination via hospital staff
Concentration- high density of infection and patients within a hospital

Question 8

What are the ESCAPE pathogens?

Answer 8

The major problems in hospital infections (first 3 gram+, last 3 gram -):
Enterococcus faecium (vancomycin resistance)
Staphylococcus aureus (MRSA)
Clostridium difficile
Acinetobacter baumanii (highly drug resistant)
Pseudomonas aeruginosa (multi-drug resistant
Enterobacteriaceae

Question 9

What is the major problem that leads to hospital infection?

Answer 9

Clinicians are forced to use older, previously discarded drugs such as colistin that are associated with significant toxicity and for which there is a lack of robust data to guide selection of dosage regimen or duration of therapy

Question 10

What is pathogenic e.coli the most frequent cause of?

Answer 10

Bacteraemia by a gram negative bacterium

Community and hospital acquired UTI

Question 11

What is happening to E.coli resistant strains?

Answer 11

There is an increase in multi-drug resistant strains. Occurrence of resistance to 3rd generation cephalosporins as high as 20% in some countries

Question 12

What do most isolates that are resistant to cephalosporin express?

Answer 12

Extended spectrum beta lactamase (ESBL)

Question 13

How responsive are isolates that are resistant to cephalosporin to carbapenems?

Answer 13

They are still sensitive

Question 14

What are cephalosporins?

Answer 14

They are a class of b-lactam antibiotic. They inhibit peptidoglycan synthesis by inhibiting the activity of penicillin binding proteins

Question 15

What does the extended spectrum b-lactamase on resistant bacteria do?

Answer 15

They are encoded on a mobile plasmid and it cleaves the cephalosporin

Question 16

What are carbapenems?

Answer 16

Class of b-lactam antibiotic that inhibits peptidoglycan synthesis by inhibiting the activity of penicillin binding proteins

Question 17

What does the carbapenemase enzyme on resistant bacteria do?

Answer 17

It is encoded on a transposon mobile genetic element and it cleaves the antibiotic

Question 18

What is klebsiella an important cause of?

Answer 18

UTI and respiratory tract infections

Question 19

What is the risk group of klebsiella?

Answer 19

Immunocompromised

Question 20

What is there a high proportion of resistant to in Klebsiella?

Answer 20

There is resistance to 3rd generation cephalosporins, fluroquinolones and aminoglycosides

Question 21

Which species of CRE is most commonly encountered in US?

Answer 21

Carbapenem resistant Klebsiella pneumoniae

Question 22

What is the risk group for pseudomonas aeruginosa?

Answer 22

Immunocompromised (high proportions of strains are resistant to antimicrobials)

Question 23

What is the most important cause of antimicrobial resistant infection worldwide?

Answer 23

Methicillin resistant s. aureus

Question 24

What sort of antibiotic is methicillin?

Answer 24

B-lactam antibiotic that inhibits peptidoglycan synthesis by inhibiting activity of penicillin binding proteins

Question 25

How is resistance to methicillin achieved by staph aureus?

Answer 25

Expression of additional penicillin binding protein (PBP2A)- has a low affinity for methicillin and thus can still function in the presence of antibiotic. MRSA can still survive and synthesise peptidoglycan

Question 26

What is vancomycin resistant enterococcus faecium the third most frequently identified cause of in the US?

Answer 26

Nosocomial bloodstream infections

Question 27

What is vancomycin resistance like in VRE?

Answer 27

60%

Question 28

What does vancomycin do?

Answer 28

Inhibits peptidoglycan synthesis by binding to precursor protein

Question 29

How is resistance to vancomycin achieved in VRE?

Answer 29

Encoding multiple protein genes on plasmid/transposon. Results in synthesis of a different peptidoglycan precursor which isn’t functional

Question 30

What is clostridium difficile?

Answer 30

A spore forming gram-positive bacterium which is a frequent complication following antibiotic therapy. However infections are now emerging in community and animals used for food

Question 31

When are patient resistant to CDI?

Answer 31

Their normal gut flora is not disrupted by antibiotics

Question 32

Why do people become vulnerable when antibiotic treatment starts to CDI?

Answer 32

Infection with a C. difficile strain that is resistant to antibiotic is more likely and when the treatment stops, levels of antibiotic in gut diminish rapidly but microflora remains disturbed for a variable period of time depending on antibiotic given. During this time patients can be infected with c. difficile. Finally after microflora recovers, colonisation resistance to C difficile is restored

Question 33

What is the pathogenesis of C.difficile?

Answer 33

C.difficile colonises the intestine after disruption of normal intestinal flora. Toxigenic strains of the bacteria then produce toxin A and B. Toxin B binds to epithelial cell membrane and then toxin A causes cytoskeletal changes that result in disruption of tight junctions and loosening of the epithelial barrier in cell death and in the production of inflammatory mediators that attract neutrophils
Both toxins are cytotoxic and induce the release of various immunomodulatory mediators from epithelial cells, phagocytes and mast cells, resulting in inflammation and accusation of neutrophils