Personal Care and Healthcare Microbiology Common Issues, Same Solutions

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Personal Care and Healthcare MicrobiologyCommon
Issues, Same Solutions?

• John Vaughan Senior Microbiologist, Technical
  services Group

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Summary

• Background
• Microbiology of Skin
• Microbiology of wounds
• Antimicrobials
• Resistance
• Combating resistance
• Test Methodologies

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Basic Background

• Microbes - 3 families, Bacteria, Protozoa and
  Fungus/Yeasts.
• Bacteria - two types based on the composition of
  their cell wall, Gram positive (S.aureus) and
  Gram Negative (E. coli).
• Normally classed as rods (torpedo shaped) or
  cocci (spherical).
• Can then be further broken down into two more
  loose categories - aerobes (requiring atmospheric
  oxygen concentrations) and anaerobes (requiring
  low/no oxygen atmosphere).

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Skin Microbiology 1

• Commensal bacterial populations of an average of
  1 x 107 bacterial cells per cm2.
• Oily areas of skin such as the face may have 1 x
  108 per cm2.
• Most commonly occurring species Gram Positive
  Cocci (Staphylococcus aureus, S. epidermidis,
  Micrococcus etc).
• Also environmental, particularly on hands
  (Coliforms, Pseudomonas aerugenosa and Bacillus
  species).
• Natural bacterial presence largely beneficial.

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Skin Microbiology 2

• Most common form of medical complaint caused by
  Microbiological imbalance is Acne Vulgaris.
• Caused by blocked pores allowing overgrowth of
  Propionibacterium acnes.
• Aerotolerent anaerobe, survives on skin, thrives
  once pore is blocked to air.
• Breaks down pore walls allowing bacteria below
  the skin causing lesions.

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Wound Microbiology 1

• Skin forms bacterial barrier that is broken when
  wound develops.
• Wounds go through different stages in the
  progress to infection.
• Colonised - less than 1 x 105 bacteria per ml of
  wound fluid.
• Critically colonised - increased to 1 x 105 - 1 x
  106 bacteria per ml.
• Infected wounds - 1 x 107 bacteria per ml and
  above.
• Typically colonised by skin bacteria and
  environmental bacteria.

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Wound Microbiology 2

• Anaerobic bacteria also contribute to wound
  infection thriving in deep oxygen free crevices.
• Most of the colonising bacteria are capable of
  causing infection opportunistically.
• Bacteria that are normally harmless are a risk
  in places they arent supposed to be!
• Pathogenesis occurs through toxin release or
  sheer weight of numbers.

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Antimicrobials - Skincare

• In both wounds and skincare a range of
  antimicrobials are available for use.
• In skincare most common are topical agents such a
  benzoyl peroxide cream in acne treatment.
• Benzoyl peroxide causes free radical release
  directly killing bacteria, releases oxygen in
  concentrations toxic to anaerobes and increases
  skin turnover so unblocking pores.
• Triclosan also in common use in handwashes etc.
• Triclosan acts by binding an enzyme involved in
  fatty acid synthesis so affecting cell wall
  manufacture.

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Antimicrobials - Woundcare

• Heavier use of antibiotics in conjunction with
  antimicrobials.
• Antimicrobials applied directly to the wound in
  the form of dressings or ointments.
• Silver in common use in both dressings (Acticoat,
  Allevyn Ag) and ointment (Flamazine).
• Silver affects wide range of targets in the cell
  giving it broad spectrum of activity and rapid
  rate of kill.
• Iodine (Iodosorb, Iodoflex) also commonly used
  and also has a broad spectrum of activity and
  rapid kill rate.

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Antibacterial Action of Silver
Mutates DNA
Blocks molecule passage into cell
Destroys proteins and enzymes
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Antimicrobial Resistance

• The biggest issue in both skincare and healthcare
  microbiology.
• Has the potential to render current
  products/actives obsolete.
• Arises through genetic transfer between bacteria
  or through mutation.
• 3 mechanisms of antimicrobial resistance
  generally recognized
• Exclusion preventing antimicrobial entering
  cell or finding target in cell.
• Inactivation Alteration of antimicrobial to
  harmless form.
• Efflux - Active pumping of antimicrobial out of
  the cell.
• Once in place mechanisms have cross resistance
  potential.

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Mechanisms of Resistance
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Combating Resistance 1

• Three elements are key
• Speed of kill - if the bacteria are wiped out
  totally and quickly then there is no chance of
  resistance evolving.
• Use of antibacterials with multiple targets -
  spontaneous development of resistance to all
  elements is unlikely.
• Use of antimicrobials only sparingly and where
  necessary. Potential cross resistance to
  antibiotics - consequences are potentially
  catastrophic.
• Overuse of triclosan in particular has caused
  concern.

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Combating Resistance 2

• Silver and Iodine are well suited to avoiding the
  development of resistance as they are both fast
  acting and hit multiple targets.
• Development of antimicrobials and products of the
  future must take these factors.
• Serious consideration needs to given before any
  antimicrobial is incorporated into any product.
• Is the potential benefit to the customer or
  sales enough to outweigh the potential
  consequences?

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The Log Reduction Method

• Known quantity of organisms inoculated into the
  antimicrobial product being tested and to a
  non-active control.
• Product incubated for a given length of time,
  before antimicrobial activity is neutralised.
• Number of remaining organisms counted and
  compared to that found in the control product
  when first inoculated.
• Can be performed using low inoculum concentration
  to asses proliferation rather than kill.

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Log Reduction Results
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Zone of Inhibition Assays

• Commonly used to determine the longevity of an
  antimicrobial product.
• Product or active is challenged with a fresh lawn
  of bacteria on each day of testing and the zone
  produced is measured.
• Often used to demonstrate a products claim for
  its wear/use time or in the case of antibiotics
  can be used to determine release quantitatively.

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The Bacterial Barrier Test

• Dressing clamped between two glass hemispheres
  filled with nutrient broth.
• Broth in contact with the outer surface of the
  dressing is inoculated with the chosen bacterial
  strain.
• Broth in contact with inner surface of dressing
  sampled regularly and checked for the presence of
  the test bacterium.

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Conclusions

• Skin and wound flora largely the same mix of
  commensals and environmental isolates.
• Pathogenesis occurs when these harmless
  bacteria are found outside their normal
  environment.
• In both cases antimicrobials applied at the
  source of infection/contamination are effective.
• Resistance is a growing issue in both fields and
  can be combated by developing antimicrobials that
  act fast on multiple targets.
• A range of microbiological techniques are
  available in the development of new
  antimicrobials and antimicrobial products.

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Technical Services Group

• Microscopy
• Spectroscopy
• Chromatography
• Microbiology
• Histology
• Materials testing
• Modelling
• Numerical analysis

• General
• Andrew Jackson PhD, Head of Technical Services
• Tel [phone]
• Fax [phone]
• Mobile [phone]
• E-mail andrew.jackson_at_smith-nephew.com
• Microbiology
• John Vaughan , Senior Microbiologist
• Tel [phone]
• Fax [phone]
• E-mail john.vaughan_at_smith-nephew.com