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Y1 TP2 Infection (topic 3 Onwards) > 6. Infections On Surfaces > Flashcards

6. Infections On Surfaces Flashcards

1
Q

What is a surface

A

—> Interface between a solid and either a liquid or gas

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2
Q

3 natural body surfaces

A

• Skin
• GI tract
• Urinary tract
We have innate mechanisms to prevent infections establishing there

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3
Q

4 artificial surfaces

A
  • Use of intravenous lines,
    • central venous line catheters,
    • NG tubes,
    • Prosthetic devices and implants provide ideal surfaces for organism to establish infection
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4
Q

Specific examples of natural surfaces

A

○ Skin – epithelieum, hair, nails
○ Mucosal surfaces = conjunctivial, gastrointestinal, respiratory, genitourinary
○ Secretion of enzymes to prevent infection of surfaces

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5
Q

What are skin microorganisms

A

e.g. commensals can casue infection udner certain circumstances

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6
Q

Skin microorganisms - viruses

A

– Papilloma

– Herpes simplex

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7
Q

Skin microorganisms - bacteria

A

Gram positive
– Staph aureus
– Coagulase negative staphylococci
– Corynebacterium

Gram negative
– Enterobacteriaceae

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8
Q

Skin microorganisms - fungi

A

– Yeasts

– Dermatophytes

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9
Q

Skin microorganisms - parasites

A

– mites

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10
Q

Microflora examples

A
  • Nasopharynx- step pneumonia
    • Nose armpits – staph aureus
    • Mouth = streptococci can dislodge and enter blood system can cause endocarditis in heart
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11
Q

Natural infection sites – external surfacses

A

– Pharyngitis – sore throat = viruses and bacteria

– Conjunctivitis – infection of conjunctiva

– Gastroenteritis - inflammation of the gastrointestinal tract due to infection giving rise to diarrhoea - due to toxins

– Urinary tract infection - infection in any part of the urinary system including kidneys, bladder, ureter, and urethra

– Pneumonia – infection of one or both lungs causing inflammation of alveoli which fill with liquid or pus

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12
Q

Natural surface infections = internal surfaces

A

– Endocarditis - infection of the endocardium, which is the inner lining of the heart chambers and heart valves.

– Septic arthritis – joint infection where microorganism invades the joint and causes inflammation

– Osteomyelitis – infection of the bone difficult to treat need antibiotics than can penetret bone

– Empyema – pus in the pleural cavity due to infection (space between the outside of the lungs and the inside of the chest cavity)

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13
Q

Cystic fibrosis

A

Mucus build up in lungs and digestive system = gives ideal environemnts for infectiosn to grow

•Patients have persistent lung infections
– Pseudomonas aeruginosa
– Mycobacterium abscessus
– Aspergillus species

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14
Q

What are adhesins

A
  • Ways bacteria attach to surface and establish infection
  • Adhesins which help bacteria bind to host surfaces for example, skin, mucous membranes (oral cavity, nasopharynx, urogenital tract), and deeper tissues (lymphoid tissue, gastric and intestinal epithelia, alveolar lining, endothelial tissue).
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15
Q

Adhesins examples

A

•Adhesins can be proteins for example fimrae (pili) as in E.coli attach themselves to the bladder mucosa or non-fimbrae proteins which facilitate adherence

  • Polysaccharide adhesins - usually components of the bacterial cell membrane, cell wall, or capsule.
    • Teichoic acids in the cell envelopes of Gram-positive bacteria serve as adhesins for Staphylococcus and Streptococcus species
    • Capsular polysaccharide (external) components (glucan and mannan) of Mycobacteria species promote adherence
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16
Q

Examples of Prosthetic surface infections

A
  • Intravascular lines
  • Central venous catheters including Hickman catheters
  • Peritoneal dialysis catheters
  • Prosthetic joints
  • Breast prostheses
  • Cardiac valves
  • Pacing wires – wires put in during heart operations to maintain heart beat
  • Endovascular grafts
  • Ventriculoperitoneal shunts
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17
Q

Sources of infection – IV line

A

• IV line – hub, liquid, breaking skin
○ Device can be contaminated as needle enters skin
○ Contamination of catheter hub
○ Infections can establish at catheter

18
Q

How to Prevent transfer of microorganism with n lines

A
  • Wash hands
    • Gloves on

Positive pressure of lines – liquid gushes out instead of limb to prevent infection

19
Q

Hickman line

A

• Used for chemotherapy
• To take antibiotics
To take blood

20
Q

Hip replacement

A
  • Ususally metal
    • Not compleletly able to prevent setlling of microorganism
    • Infection tends to be at head of prosthetic device
21
Q

Staph aureus on the surface of an indwelling catheter

A

• Microorganisms have a polysaccharide coating and matrix
• They produce slime = slime creates biofilm
○ Biofilm = difficult for antibiotics or immune cells to penetrate

Bacteria settle on surface
Wait for right environment to multiply
Build polysaccharide matrix and biofilm to protect themselves from immune system

22
Q

Infections of join replacement

A

• Operation required to take out infected joint

Revision surgery = taking replacements out and adding in spacer with antibiotiv to clear area of infection, biut it is more likely for second joint to be infected

  • Require antibiotic therapy for weeks or months
  • Longer stay in hospital Incidence of infection:
23
Q

Microorganisms causing infections

• Early post operative infections (1 month)

A

– S.aureus, Gram-negative organisms ( E.coli, Proteus, Klebsiella), Enterobacteraceae, Enterococci (E.faecalis)

24
Q

Microorganisms causing infections

• Late post operative infection 2 to >12 months (takes longer for infection to establish):

A

• Coagulase negative Staphylococci (mainly Staphylococcus epidermidis) and Staphylococcus aureus, to a lesser extent other species for example: Staphylococcus haemolyticus, Staphylococcus simulans, Staphylococcus warneri Enterobacteraceae

25
Q

Endocarditis

—> organisms going to heart valve and causes endocarditis

A
  • Coagulase negative Staphylococci including S.epidermidis
  • Staphylococcus aureus
  • Viridans streptococci
  • Enterococcus faecalis
  • Staphylococcus aureus
  • HACEK group (Haemophilus species, Aggregatibacter species,Cardiobacterium hominis, Eikenella corrodens, and Kingella species
  • Candida
26
Q

4 Process of pathogeneisis of infection at surfaces

A
  • Adherence to host cells or prosthetic surface
  • Biofilm formation
  • Invasion and multiplication
  • Host response
27
Q

3 Stages of biofilm development

A
  • Attachment
  • Maturation
  • Dispersion
28
Q

Biofilm maturation

A
  1. Microorganism come to surface but become dormant due to not enough nutrients
    1. Microorganisms activate and multiply
    2. Microorganisms do quorum sensing – communicate and bring microorganism
    3. Form biofilm
    4. Biofilm sheers and floats of with microorganisms
    5. Spreads the infection
29
Q

What is Quorum sensing

A

—> communication of bacteria with each other and formation of biofilm

30
Q

Quorum sensing

Controls

A

– Sporulation
– Biofilm formation
– Virulence factor secretion

31
Q

Quorum sensing

Three principles

A

– Signalling molecules – autoinducers (AI) secreted by microorganism
– Cell surface or cytoplasmic receptors detect signalling molecules
– Gene expression ->co-operative behaviours and more AI production., message causes change in infection

32
Q

5 Symptoms of infection

A
  • Fever (generally yes but not everyone gets fever)
  • Inflammation at the site of insertion
  • Purulence or erythema – pus at site of infection
  • Pain
  • Malaise
33
Q

Investigations of infection

A 
•Full Blood Count = blood cells and neutrophils 
•C reactive proteins 
•ESR 
•Blood culture (looking for organisms in patients blood)
 – Gram stain
 – Antibiotic sensitivity 
•Samples (fluid, biopsy)
 – Bacterial Growth
 – PCR 
•Scans
34
Q

Infection Management

A

Diagnosis • Aim is to identify infecting organism and its antimicrobial susceptibilities.

• Challenges = trying to id organism takes time so first give broad spectrum antibiotics
– Adherent organisms - biofilm
– Low metabolic state/small colony variants (bacteria don’t go through the state or actions that antibiotics targets)

  • Blood cultures
  • Tissue/prosthetic material sonication and culture
35
Q

Aim of treatments

A

– sterilise tissue

– reduce bioburden

36
Q

Treatment examples

A
  • Antibacterials
  • Remove prosthetic material - remove thing causing infection like iv lines etc
  • Surgery – resect infected material
37
Q

Challenges of treatment to organisms with biofilm

A

– poor antibacterial penetration into biofilm
– low metabolic activity of biofilm micro-organisms
– dangers/difficulties of surgery

38
Q

Prevention of infection on natural surfaces

A
  • Maintain surface integrity
    • Prevent bacterial surface colonisation
    • Remove colonizing bacteria (clean patient)
39
Q

Prevention of infection on prosthetic surfaces

A
  • Prevent contamination
    • Inhibit surface colonisation
    • Removing colonising bacteria
40
Q

Coagulase test

A

Test to see if organism produces coagulase or not

Add blood plasma

  • if clumping is present = coagulative positive
  • if clumping is not present = coagulativenegative

Y1 TP2 Infection (topic 3 Onwards) (9 decks)

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