ANTIMICROBIAL SENSITIVITY OF Staphylococcus aureus AND Escherichia coli TO SELECTED ANTIBIOTICS

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ABSTRACT

Antimicrobial resistant and susceptibility pattern of Staphylococcus aureus and Escherichia coli was studied. Antimicrobial sensitivity patterns of both organisms were determined using disc diffusion method. The susceptibility test showed that Staphylococcus aureus was higly sensitive to Gentamicin (40mm), moderately sensitive to Streptomycin (29mm) and Ampicillin (25mm). While Escherichia coli was highly sensitive to Gentamicin (28mm), moderately sensitive against Streptomycin (23mm) but susceptibility was very low in Ampicillin (8mm). Escherichia coli showed low susceptibility to Ampicillin. Therefore, the public should be sensitized on the use of antibiotic to ensure effective treatment of infection.

 

 

 

CHAPTER ONE

1.1 INTRODUCTION

Antibiotics also known as antibacterial are medications that destroy or slow down the growth of bacteria. They include range of drugs and are used to treat disease caused by bacteria. Antibiotics can also be classified based on their chemical structure. A similar level of effectiveness, toxicity and side-effect is rendered by the antibiotics of the same structural group (Bernard, 2010).

Sir Alexander Fleming, a Scottish biologist, defines new horizons of modern antibiotics with his discoveries of enzyme lysozyme (1921) and the antibiotic substance Penicillin (1928). The discovery of penicillin from fungus Penicillin notatum perfected the treatment bacterial infections such ad syphilis, gangrene and tuberculosis. He also contributed immensely towards medical sciences with his writings on the subjects of bacteriology, immunology.

The ability of antibiotics to cure infectious diseases that were previously fatal has led to the notion that they are “miracle drug” And that they posses powers widely exceeding those which can be attributed to their actual pharmacological properties. In most developed countries, antibiotics are the second mostly used class of drugs after simple analgesics (Conly andJohnson, 2005).

These drugs have served millions of lives. However the misuse of antibiotics has led to serious problems. Not all antimicrobials at the concentration required to be effective are completely non-toxic to human cells. Most, however, show sufficient selective toxicity to be of value in the treatment of microbial diseases. Antimicrobial agents can be grouped by their mode of action, i.e., their ability to inhibit the synthesis of the cell wall, cell membrane, proteins, and nucleic acids of bacteria (Cheesbrough, 2006).

Perhaps the most important public health problem of today is the rapid development and proliferation of antibiotic resistant bacteria. The year of widespread use of antibiotics has witnessed enormous changes in the bacteria that commonly infect human beings. Indiscriminate use of these relatively easily produced compounds has lead to crises in many areas. In many countries antibiotics are widely available over the counter with “black market” production and distribution common use in animal husbandry as “growth promoters” has reached massive levels as consumers demand inexpensive meat (Cheesbrough, 2006).

 

1.2 STATEMENT OF PROBLEM

Most people abuse antibiotics owing to the general believe that antibiotics can be used in the treatment of all kinds of diseases. This can result to drug resistance; accumulation of these drugs can lead to internal damage. Hence this study which compares the antimicrobial strength of three most commonly used antibiotics.

 

1.3   AIM AND OBJECTIVE OF THE STUDY

1.3.1 AIM OF THE STUDY

This study is aimed at the determination of the sensitivity of Staphylococcusaureus and Escherichiacoli to Gentamicin, Streptomycin and Ampicillin.

1.3.2 OBJECTIVE OF THE STUDY

  1. To determine the antimicrobial strength of three most commonly used antibiotics (Gentamicin, Streptomycin and Ampicillin).
  2. To compare the strength of antibiotics (gentamicin, streptomycin, ampicillin).

1.4 SIGNIFICANCE OF THE STUDY

  1. The study reveals the knowledge of the strength of antibiotics and how touse them adequately.
  2. The study exposes the mechanisms of action of antibiotics.
  3. The study also exposes the importance of antimicrobial susceptibility (sensitivity) test.

1.5 SCOPE OF THE STUDY

This work will center on the sensitivity and resistivity of some antibiotics and to compare the strength of the antibiotics (Gentamicin, Streptomycin and Ampicillin).

1.6 LIMITATION OF THE STUDY

  1. There is no constant power supply in the school for sterilization and incubation of the sample.
  2. Shortage of finance to buy the materials needed for the experiment.
  3. This exercise generated huge amount of stress that was almost impossible to overcome with a short time frame.

1.7 DEFINITION OF TERMS

  1. ANTIBIOTICS: These are medications that destroy or slow down the growth of bacteria.
  2. SUSCEPTIBILITY: A total or partial vulnerability to an infection.
  3. RESISTANCE: Opposition to physical or psychological process.
  4. BACTERICIDE: An agent that inhibit the growth and reproduction of bacteria.
  5. BACTERIOSTATIC: An agent that kills bacteria.
  6. NARROW- SPECTRUM DRUGS: These drugs that effective only against a limited variety of pathogens.
  7. BROAD-SPECTRUM DRUGS: Drugs that attack different kind of pathogens.

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