Antibiotics are chemicals that inhibit specific bacteria. Compound or substance that kills or slows down the growth of bacteria.
Are classified into anti-infective agents, Are made in three ways:
- By living microorganisms
- By synthetic manufacture
- Rarely through genetic engineering.
Antibiotics may be:
Bacteriostatic (preventing the growth of bacteria) or
Bactericidal (killing bacteria directly) However, several antibiotics are both bactericidal and bacteriostatic, depending on the concentration of the particular drug.
Classification of Antibiotic
Are classified into the following classes:
1. Aminoglycosides
2. Carbapenems
3. Cephalosporins
4. Fluoroquinolones
5. Penicillin's (and penicillinase-resistant drugs)
6. Sulfonamides
7. Tetracyclines
8. Disease-specific antimycobacterial (antitubercular and leprostatic drugs)
10. Ketolides (E.g.: telithromycin)
11. Lincosamides
12. Lipoglycopeptides (E.g.: televancin)
13. Macrolides
14.Monobactams (E.g.: aztreonam)
Bacteria can invade the human body through many routes. The goal of antibiotic therapy is to decrease the population of invading bacteria to a point at which the human immune system can effectively deal with the invader.
To determine which antibiotic will effectively interfere with the specific proteins or enzyme systems for treatment of a specific infection, the causative organism must be identified through a culture. Sensitivity testing is also done to determine the antibiotic to which that particular organism is most sensitive (e.g., which antibiotic best kills or controls the bacteria). Sometimes, culture and sensitivity testing may not be possible:
either because the source of the infection is not identifiable or because the patient is too sick to wait for test results to determine the best treatment
In this case, clinicians attempt to administer a drug with a broad spectrum of activity against gram-positive or gram-negative bacteria or against anaerobic bacteria.
Drugs with broad spectrum activity are often given at the beginning of treatment until the exact organism and sensitivity can be established.
Because these antibiotics have such a wide range of effects, they are frequently associated with adverse effects.
Human cells have many of the same properties as bacterial cells and can be affected in much the same way, so damage may occur to the human cells, as well as to the bacterial cells
There is no perfect antibiotic that is without effect on the human host. Therefore, health personnel try to select an antibiotic with selective toxicity, or the ability to strike foreign cells with little or no effect on human cells. Certain antibiotics may be contraindicated in some patients because of known adverse effects.Some patients for which antibiotics are contraindicated due to known adverse reactions include:
The antibiotic of choice is one that affects the causative organism and leads to the fewest adverse effects for the patient involved.
1. Immunocompromised patients
2. Patients with severe GI disease
3. Patients who are debilitated
In some cases, antibiotics are given in combination because they are synergistic. Use of synergistic antibiotics also allows the patient to take a lower dose of each antibiotic to achieve the desired effect. This helps to reduce the adverse effects that a particular drug may have.
In some situations, antibiotics are used as a means of prophylaxis, or prevention of potential infection.