Main Difference – Bactericidal vs Bacteriostatic
Bactericidal and bacteriostatic are two types of antibiotics classified based on the mode of action. Bactericidal and bacteriostatic may differ in many ways. Bactericidal antibiotics inhibit the cell wall synthesis in bacteria. In contrast, bacteriostatic antibiotics inhibit the protein synthesis, the DNA replication, and other aspects of bacterial metabolism. Antibiotics with bacteriostatic activity work together with the immune system of the host in order to remove pathogens. The main difference bactericidal and bacteriostatic is that bactericidal is a type of antibiotic that kills bacteria whereas bacteriostatic is a type of antibiotics that inhibit the growth and reproduction of bacteria.
Key Areas Covered
1. What is Bactericidal
– Definition, Types, Action Mechanism
2. What is Bacteriostatic
– Definition, Types, Action Mechanism
3. What are the similarities between Bactericidal and Bacteriostatic
– Outline of Common Features
4. What is the difference between Bactericidal and Bacteriostatic
– Comparison of Key Differences
Key Terms: Antibiotics, Bacteria, Bactericidal, Bacteriostatic, DNA Replication, Minimum Bactericidal Concentration (MBC), Minimum Inhibitory Concentration (MIC), Protein Synthesis
What is Bactericidal
Bactericidal is a type of antibiotics that kill bacteria. The action of bactericidal is irreversible. Several mechanisms are involved in the killing of bacteria by bactericidal antibiotics. Beta-lactam antibiotics, cephalosporins, and vancomycin inhibit the cell wall synthesis of bacteria. The damaged membrane allows the pouring out of the content inside the bacterial cell. This causes the death of the bacteria. Other antibiotics that are bactericidal may inhibit protein synthesis or bacterial enzymes. The minimum bactericidal concentration (MBC) refers to the concentration of the drug required to kill 99.99% of the bacterial population. Penicillin is a beta-lactam antibiotic, inhibiting the cross-linking of bacterial cell wall by attaching to penicillin-binding proteins. The action of penicillin is shown in figure 1.
Figure 1: The Action of Penicillin
What is Bacteriostatic
Bacteriostatic antibiotics limit the growth of bacteria. Its action is reversible. When the bacteriostatic antibiotic is removed from the system, normal growth of bacteria can be observed. Bacteriostatic antibiotics inhibit bacterial DNA replication, protein synthesis and other aspects of bacterial metabolism. These antibiotics work along with the immune system of the host in order to prevent the bacterial growth and reproduction. High concentrations of some of the bacteriostatic antibiotics can be bactericidal. Tetracyclines, spectinomycin, chloramphenicol, sulfonamides, trimethoprim, lincosamides, and macrolides are examples of bacteriostatic antibiotics. The minimum inhibitory concentration (MIC) is the minimum drug concentration which inhibits the bacterial growth. The inhibition of the successive steps of tetrahydrofolate synthesis pathway by sulfonamides and trimethoprim is shown in figure 2. Tetrahydrofolate is involved in the nucleotide synthesis. Ultimately, the inhibition of the production of tetrahydrofolate leads to defective DNA replication.
Figure 2: Inhibition of Tetrahydrofolate Synthesis Pathway
Similarities Between Bactericidal and Bacteriostatic
- Bactericidal and bacteriostatic are two types of antibiotics that prevent the bacterial growth and reproduction.
Difference Between Bactericidal and Bacteriostatic
Definition
Bactericidal: The antibiotics that kill bacteria are referred to as bactericidal.
Bacteriostatic: The antibiotics that prevent the growth of bacteria are referred to as bacteriostatic.
Mode of Action
Bactericidal: Bactericidal antibiotics kill bacteria.
Bacteriostatic: Bacteriostatic antibiotics inhibit the growth of bacteria.
Reversible/Irreversible
Bactericidal: The action of bactericidal antibiotics is irreversible.
Bacteriostatic: The action of bacteriostatic antibiotics is reversible.
Function
Bactericidal: Bactericidal antibiotics inhibit the cell wall formation of bacteria.
Bacteriostatic: Bacteriostatic antibiotics inhibit DNA replication and protein synthesis of bacteria.
Immune System
Bactericidal: Bactericidal antibiotics do not work with the immune system of the host.
Bacteriostatic: Bacteriostatic antibiotics work with the immune system of the host in order to prevent the growth and reproduction of bacteria.
Concentration Measurements
Bactericidal: The MBC refers to the concentration of the drug required to kill 99.99% of the bacterial population.
Bacteriostatic: The MIC is the minimum drug concentration which inhibits the bacterial growth.
Examples
Bactericidal: Beta-lactam antibiotics, cephalosporins, and vancomycin are examples of bactericidal antibiotics.
Bacteriostatic: Tetracyclines, spectinomycin, chloramphenicol, sulfonamides, trimethoprim, lincosamides, and macrolides are the examples of bacteriostatic antibiotics.
Conclusion
Bactericidal and bacteriostatic are two types of antibiotics used in preventing bacterial growth. The main difference between bactericidal and bacteriostatic antibiotics is their mode of action. Bactericidal antibiotics directly kill bacteria by inhibiting the bacterial cell wall formation. Hence, the action of bactericidal antibiotics is irreversible. In contrast, bacteriostatic antibiotics inhibit the DNA replication and protein synthesis of bacteria. The action of bacteriostatic antibiotics is reversible. High concentrations of bacteriostatic antibiotics may exhibit bactericidal in action.
Reference:
1. “Types of Antibiotics: Bactericidal vs.Bacteriostatic & Narrow Spectrum vs. Broad Spectrum.” Study.com. N.p., n.d. Web. Available here. 21 June 2017.
2. “Antibiotic Classifications.” Boundless. N.p., 26 May 2016. Web. Available here. 21 June 2017.
Image Courtesy:
1. “Penicillin inhibition” By Mcstrother – Own work (CC BY 3.0) via Commons Wikimedia
2. “THFsynthesispathway” (CC BY-SA 3.0) via Commons Wikimedia
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