Bacteria and Virus: Introduction, Differences, and Keynotes

Introduction of Bacteria and Virus

Bacteria are member of a large group of living unicellular microbes having size of cocci 0.5-1.0 µm while bacilli 1-10 µm×3-10µm which have cell walls but lacking an organized nucleus, including some that can cause disease like pneumonia, tuberculosis, food poisoning, etc. They are visible under light microscope. Some example of Gram positive bacteria (Staphylococcus, Pneumococcus, Streptococcus pyogenes, Streptococcus agalactiae, Enterococcus species) and Gram negative bacteria (E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus, Citrobacter, Enterobacter, Salmonella, and Shigella)

Virus is an infective agent that typically consists of a nucleic acid (either DNA or RNA) molecule in a protein coat, is too tiny to be seen by light microscopy, and is able to multiply only within the living cells of a host (obligate intracellular parasite). It is visible only under electron microscope and having size of smallest-parvovirus-20 nm while largest poxvirus-300 nm. Few viral diseases are influenza, AIDS, measles, polio, and COVID-19. Some example of viruses- DNA virus (Hepatitis B virus, human papillomavirus ) and RNA virus (HIV, SARS-CoV-2, Hepatitis C virus and Dengue virus)

Differences between Bacteria and Virus

The differences between bacteria and viruses are as follows-

S. No.	Characters	Bacteria	Virus
1	Plasma membrane	Yes	No
2	Intracellular parasite	No (except Rickettsia and Chlamydia)	Yes
3	Ribosomes	Yes	No
4	Possess both DNA and RNA	Yes	No
5	ATP-generating metabolism	Yes (except Chlamydia)	No
6	Binary fission	Yes	No
7	Pass through bacteriological filters	Yes (except Chlamydia)	No
8	Sensitive to antibiotics	Yes	No
9	Sensitive to interferon	No	Yes
10	Living organisms	Yes	No
11	Quorum sensing	Yes	No
12	Microscopy	Compound microscope	Electron microscope
13	Size of Microbes	Cocci 0.5-1.0 µm while bacilli 1-10 µm×3-10µm	Smallest-Parvo virus-20 nm while largest –Pox virus-300 nm
14	Disease caused	Pneumonia, tuberculosis, food poisoning, and tetanus	Influenza, AIDS, measles, polio, and COVID-19

Keynotes on Bacteria and Virus

• Rickettsia and Chlamydia of bacteria are intracelluar parasites.
• Virus is acellular organism due to lacking typical cell.
• Causative agent of COVID-19 is severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2).

Bibliography

1. Jawetz, Melnick and Adelberg’s Medical Microbiology. Editors: Geo. F. Brook, Janet S. Butel & Stephen A. Morse, 21st ed 1998, Publisher Appleton & Lance, Co Stamford Connecticut.
2. Mackie and Mc Cartney Practical Medical Microbiology. Editors: J.G. Colle, A.G. Fraser, B.P. Marmion, A. Simmous, 4th ed, Publisher Churchill Living Stone, New York, Melborne, Sans Franscisco 1996.
3. Textbook of Diagnostic Microbiology. Editors: Connie R. Mahon, Donald G. Lehman & George Manuselis, 3rd edition2007, Publisher Elsevier.
4. https://universe84a.com/microscope
5. https://www.merriam-webster.com/words-at-play/virus-vs-bacteria-difference