Infections On Surfaces

Question 1

What is meant by a surface?

Answer 1

Any interface between a solid and either a liquid or a gas

Question 2

What does the microbiota consist of?

Answer 2

The microorganisms that are carried on the skin and mucosal surfaces

Question 3

What is normally true of the microbiota?

Answer 3

They are normally harmless, or even beneficial

Question 4

When can microbiota be harmful?

Answer 4

When they transfer to other sites

Question 5

What are the categories of normal skin flora?

Answer 5

Gram positive coccus

Gram positive bacilli

Question 6

What are the gram positive coccus found in the skin flora?

Answer 6

Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus species

Question 7

What are the gram positive bacilli found in the skin flora?

Answer 7

Corynebacterium species

Propionibacterium species

Question 8

What are the mucosal flora found in the eye?

Answer 8

Coagulase negative staph
Diphtheroids
Saprophytic neisseria species
Viridans group streptococci

Question 9

What are the mucosal flora found in the nares?

Answer 9

Staph aureus

Question 10

What are the mucosal flora found in the nasopharynx?

Answer 10

Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae

Question 11

What are the mucosal flora found in the mouth?

Answer 11

Viridans streptococci
Neisseria
Veillonella
Lactobacillus
Actinomyces
Bacteroides
Capnocytophaga
Eikenella
Prevotella
Fusobacteria
Clostridia
Propionibacteria
Candida
Ceotrichum species

Question 12

What are the mucosal flora found in the stomach?

Answer 12

Helicobacter
Streptococci
Staphylococci
Lactobacilli

Question 13

What are the mucosal flora found in the intestine?

Answer 13

Bacteroides
Bifidobacterium
Eubacterium 
Lactobacillus
Coliforms
Aerobic and anaerobic streptococci
Clostridium 
Yeasts

Question 14

What are the mucosal flora found in the urethra?

Answer 14

Enterobacteriaceae
Lactobacilli
Diphtheroids
Alpha and non-haemolytic streptococci
Entercocci

Question 15

What are the mucosal flora found in the vagina?

Answer 15

Lactobacilli
Diphtheroids
Micrococci
Coagulase-negative staphlococci
Enterococcus faecalis
Microaerophilic and anaerobic streptococci
Mycoplasmas
Ureaplasmas
Yeasts

Question 16

How is a coagulase test conducted?

Answer 16

By testing for coagulase in a test tube

Question 17

How can you tell if coagulase is being produced in a coagulase test?

Answer 17

If plasma clots on addition of bacteria

Question 18

What does a positive coagulase test indicate?

Answer 18

The staphylococcus in question is staph aureus- all other staphylococci are coagulase negative

Question 19

What is the problem with surface infections?

Answer 19

They can be a major cause of hospital acquired infection

Question 20

How can surface infections be acquired in hospitals?

Answer 20

Prosthetic surfaces that are implanted during surgeries

Infections of the mucosa or skin caused by procedures or invasive devices

Question 21

What prosthetic surfaces implanted during surgery can cause a surface infection?

Answer 21

Pacemaker

Joint replacements

Question 22

What invasive devices can result in a hospital acquired surface infection?

Answer 22

Cannulas

Catheters

Question 23

How can the majority of hospital acquired surface infections be prevented?

Answer 23

Proper sterilisation of surfaces

Care during the procedure

Question 24

What is the problem with HAIs?

Answer 24

Cost a large amount of money

Have a large negative impact on the outcome of treatment, and can often even cause death

Question 25

Why do HAIs cost a large amount of money?

Answer 25

Cost of investigations Treatments Extended hospital stays Loss of reputation and subsequent funding

Question 26

Give 6 internal infections on natural surfaces

Answer 26

``` Cellulitis Pharyngitis Conjunctivitis Gastroenteritis UTI Pneumonia ```

Question 27

What pathogens can cause cellulitis?

Answer 27

Strep. pyogenes | Clostridium perfingens

Question 28

What pathogens can cause pharyngitis?

Answer 28

Strep. Pyogenes Mycoplasma pneumoniae Adenovirus

Question 29

What pathogens can cause conjunctivitis?

Answer 29

Adenovirus | Staphlococcus aureus

Question 30

What pathogens can cause gastroenteritis?

Answer 30

Salmonella Norovirus Rotavirus

Question 31

What pathogens can cause UTIs?

Answer 31

E. coli Staph. Saphrophyticus Klebsiella

Question 32

What pathogens can cause pneumonia?

Answer 32

Strep. Pneumoniae Staph. Aureus Haemophilus influenza

Question 33

Give 5 external infections on natural surfaces

Answer 33

``` Endocarditis Vasculitis Septic arthritis Osteomyelitis Empyema ```

Question 34

What pathogens can cause endocarditis?

Answer 34

Staph. Aureus Strep. Mutans Pseudomonas

Question 35

What pathogens can cause vasculitis?

Answer 35

HTLV-1 (human T-cell lymphotrophic virus)

Question 36

What does HTLV-1 cause?

Answer 36

Retinal vasculitis

Question 37

What pathogens can cause septic arthritis?

Answer 37

Neisseria gonorrhoea | Haemophilus influenzae

Question 38

What pathogens can cause osteomyelitis?

Answer 38

Staph. Aureus | Aspergillus

Question 39

What is empyema?

Answer 39

Infection between pleural membranes

Question 40

What pathogens can cause empyema?

Answer 40

Strep. Pneumoniae | Staph. Aureus

Question 41

What prosthetic surfaces can get infected?

Answer 41

``` Intravascular lines Peritoneal dialysis catheters Prosthetic joints Cardiac valves Pacing wires Endovascular grafts Ventrico-peritoneal shunts ```

Question 42

What pathogens cause infection on prosthetic joints?

Answer 42

Coagulase negative staphylococcus | Staph aureus

Question 43

What are the categories of infection on cardiac valves?

Answer 43

Native valves and prosthetic valve endocarditis >1 year post op Prosthetic valve endocarditis <1 year post-op

Question 44

What pathogens can cause native valves and prosthetic valve endocarditis >1 year post op?

Answer 44

Viridans streptococci Staph. Aureus Candida HACEK group

Question 45

What pathogens can cause prosthetic valve endocarditis <1 year post-op?

Answer 45

Coagulase negative staph

Question 46

What infection can occur on pacing wires?

Answer 46

Cardiac pacing wire endocarditis

Question 47

What pathogens can cause cardiac pacing wire endocarditis?

Answer 47

Coagulase negative staph | Staph. Aureus

Question 48

What are the steps in the pathogenesis of infections at a surface?

Answer 48

``` Adherence to host cells or prosthetic surface Biofilm formation Quorom secretion Invasion and multiplication Host response ```

Question 49

What enhance adherence to host cells or prosthetic surface?

Answer 49

Pili or fimbriae

Question 50

How do biofilms form?

Answer 50

Bacteria excrete polymers which bind with water molecules to form a slimy matrix The bacteria become embedded within the 'gel'

Question 51

What polymers can bacteria excrete to produce biofilms?

Answer 51

Proteins Lipids Nucleotides

Question 52

Why do biofilms aid bacterial survival?

Answer 52

These bacteria have a slower turnover Antibiotics don't work or attach as well Nutrients can't diffuse into the matrix Chemical gradients create microenvironments for different microbial species

Question 53

What is the purpose of quorom secretion?

Answer 53

Intracellular communication between bacteria

Question 54

What does intracellular communication between bacteria using quorom secretion involve?

Answer 54

Signalling molecules Cell surface or cytoplasmic receptors Gene expression

Question 55

What signalling molecules are involved in quorom secretion?

Answer 55

Autoinducers

Question 56

What is the purpose of gene expression in quorom secretion?

Answer 56

Co-operative behaviours and more AI production

Question 57

What does quorom secretion allow?

Answer 57

Bacteria to sense the number of nearby bacteria

Question 58

What happens if, through quorom secretion, the bacteria can sense the number of bacteria is big enough?

Answer 58

Biofilm can be formed

Question 59

What does quorum sensing control?

Answer 59

Sporulation | Virulence factor secretion

Question 60

What can the host response to infections at surfaces involve?

Answer 60

Pyogenic response | Granulomatous

Question 61

What happens in a pyogenic response?

Answer 61

Neutrophils produce pus

Question 62

What happens in a granulomatous response?

Answer 62

Fibroblasts, lymphocytes, and macrophages produce nodular inflammatory lesions

Question 63

What are the main steps in managing infected surfaces?

Answer 63

Diagnosis Treatment Prevention

Question 64

What is the aim of diagnosis in the management of infected surfaces?

Answer 64

Identify infecting organism and its antimicrobial susceptibilities

Question 65

How can an infected surface diagnosis be made?

Answer 65

Blood cultures | Tissue/prosthetic material sonication and culture

Question 66

What are the challenges in diagnosis of infected surfaces?

Answer 66

Adherent organisms | Low metabolic state/small colony variants

Question 67

What is the aim of treatment of infected surfaces?

Answer 67

Sterilise tissue and reduce bioburden

Question 68

How can infected surfaces be treated?

Answer 68

Antibacterials Remove prosthetic material Surgery to resect infected material

Question 69

What are the challenges in the treatment of infected surfaces?

Answer 69

Poor antibacterial penetration into biofilm Low metabolic activity of biofilm microorganisms Dangers/difficulties of surgery

Question 70

How can infection on natural surfaces be prevented?

Answer 70

Maintain surface integrity Prevent bacterial surface colonisation Remove colonising bacteria

Question 71

How can infection on prosthetic surfaces be prevented?

Answer 71

Prevent contamination Inhibit surface colonisation Remove colonising bactera