The Antibiotic Sensitivity Test

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The Antibiotic Sensitivity Test

• Presented by Marian Mikhail
• Undergraduate student
• Biology Major
• Health and Science Concentration
• Tennessee Tech University
• Cookeville, Tennessee 38505

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Introduction

• Problem susceptibly or resistance of bacteria to
  antibiotics
• All isolates should be tested by Kirby Bauer
  disc diffusion test on Muller- Hinton
  agar plate according to the standard procedure
  outlined in national committee for clinical
  laboratory standards (Briggs 1999).
• Salmonella typhi in asymptomatic typhoid and to
  find out drug resistance and ability of strains
  to transmit drug resistance to other bacteria
  (senthilkumar and prabakaran 2005).
• Determine the susceptibility of an opportunistic
  pathogen to antimicrobial agent (Goss 2007).

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Introduction

• Shigella isolates resistant to a variety of
  agents have been reported in the united states
  (Ashkenazi 1994).
• The routine use of antibiotics in medical and
  agricultural circles has resulted in widespread
  antibiotic resistance and in the development of
  genetic mechanisms efficient for the
  dissemination of antibiotic gene cassettes,
  especially within and between species of
  gram-negative organisms (Briggs 1999).

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Introduction

• Prevention monitoring program has detected the
  first U.S. case of Shigella infection resistant
  to the fluoroquinolone (moon2003).
• chloramphenicol was the first-line drug of
  choice, and in developed countries its use
  resulted in a reduction in mortality rates from
  10 to lt2. After extensive outbreaks of typhoid
  fever occurred in Mexico and India in the early
  and mid-1970s, in which epidemic strains were
  resistant to chloramphenicol , the efficacy of
  this antimicrobial was in doubt(John et al
  1999).

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Objective ,hypothesis, Null hypothesis

• Objective to show Antibiotics sensitivity test
  (disc diffusion method) importance in determining
  the proper antibiotics treatment in different
  species in enterobacteriaceae family.
• Hypothesis different species in the same
  bacterial family like the enterobacteriaceae
  family (gram negative rods) will have different
  susceptibility or resistance to antibiotics
• Null hypothesis different species in the same
  bacterial family like the enterobacteriaceae
  family (gram negative rods) will have the same
  susceptibility or resistance to antibiotics

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Methods and materials

• Materials
• antibiotics plate Muller
• Hinton plate)- antibiotics different
• species of bacteria in the
• enterobacteriacae family-proper
• antiseptic technique
• EXPERIMENTAL DESIGN (Goss 2007).
• Disc diffusion method
• Data
• Interpretation table

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Methods and materials

• Antibiotics used in the
  experiment
• AM-ampicillin 10mg
• TE-tetracycline 30mg
• CIP-ciprofloxacin 5mg
• GM-gentamycin 10mg
• Bacteria used in the
  experiment
• Escherichia coli ,Escherichia coli
  O157H7, Shigella boydii Shigella sonnei,Yesinia
  enterocolitica Kelebsilla pneumoniae,Providencia
  stuartii,Morganella morganii Salmonella
  typhumurium, salmonella typhi

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Results

• Formation of zone of inhibition
• Measuring the zone of inhibition
• The greater the inhibition zone that means that
  the bacteria are susceptible to antibiotics
• The lesser the inhibition zone that means that
  bacteria are resistant to antibiotics
• If no zone of inhibition is formed that means
  that the bacteria are resistant to antibiotics

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• RESULTS

Bacteria AM TE CIP GM
1-E-coli 17/S 19/S 30/S 19/S
2-E-coli O157H7 17/S 18/I 29/S 15/S
3-Shigella boydii 20/S 20/S 40/S 15/S
4-Shigella sonnei, 19/S 20/S 35/S 12/R
5-yersinia 0/R 20/S 33/S 17/S
6-Kelebsilla 0/R 16/I 40/S 12/S
7-Providencia 0/R 0/R 32/S 13/I
8-Morganella 0/R 21/S 40/S 17/S
9-Salmonella tyhi 17/S 17/S 32/S 19/S
10-Salmonella typhimurium 25/S 17/I 35/S 17/S
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• Statistics of the zone of inhibition of this
  family
• mean
• 786/4019.65mm

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Results
1-E-coli 2- E-coli O157H7 3-shigella boydii 4-shigella sonnei 5-yersinia 6-Kelebsilla 7-Providencia 8-Morganella 9-Salmonella Tyhi 10-Salmonella typhimurium


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DICUSSION

• The disc sensitivity test has therefore been
  the main method by which we have been determined
  the susceptibility of organisms and by which we
  have kept track on resistance itself (Kerr
  2007).
• salmonella typhi have remained uniformly
  susceptible to quionlones and third generation
  cephalosporins antibiotics although the clinical
  response to cephalosporins is significantly
  become inferior(wain).

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Discussion

• All pathogenic Yersinia enterocolitica strains
  isolated in our laboratory belonged to serogroup
  O3 (biotype 4). From 1985 to 1987, we isolated
  75 strains. They were all resistant to ampicillin
  and cephalothin but were susceptible to
  co-amoxiclav, cefotaxime, tetracyclines,
  gentamicin, and nalidixic acid. Seventy-two
  percent were resistant to streptomycin, 45 were
  resistant to sulfonamides, 28 were resistant to
  trimethoprim-sulfamethoxazole, and 20 were
  resistant to chloramphenicol. Only 20 strains
  were isolated throughout the period from 1995 to
  1998. All were resistant to ampicillin and
  cephalothin but were susceptible to co-amoxiclav,
  cefotaxime, gentamicin, and ciprofloxacin. The
  rate of resistance increased up to 90 for
  streptomycin and sulfonamides, 70 for
  trimethoprim-sulfamethoxazole, 60 for
  chloramphenicol, and 5 for nalidixic acid(Prats
  2000).

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Discussion

• resistant kelebsiella to gentamycin were
  isolated from more than one body site but the
  urinary and respiratory tract were involved in
  each case(Rennnie 1976).
• The relative antimicrobial susceptibilities of
  different Shigella spp. may vary geographically
  (Chu 1998).

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CONCLUSION

• After running this experiment, I will accept my
  hypothesis because there are different
  susceptibility and resistant to antibiotics in
  the same family like in kelebsiella ,yersenia ,
  and shigella and they are all in the same family
• Ciprofloxacin is the best drug for treatment of
  diseases caused by enteriobacteriacae family but
  we have to do the antibiotic sensitivity test
  before giving the drug because peoples in
  different area develop different resistance and
  susceptibility to antibiotics and in my
  experiment I was dealing with the lab bacteria.
• The main reason for resistance is the overuse of
  antibiotics especially if people take medicine
  without doing the antibiotic sensitivity test ,
  that will develop resistance.

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I would like to thank you for your attention
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• Questions