Difference Between Parasite and Bacteria

The key difference between parasite and bacteria is that the bacteria are unicellular microscopic prokaryotes living all over while parasites are the organisms that live on or in their hosts while causing infections to hosts.

Parasite and bacteria are organisms that resemble very primitive organisms but have great adaptations to survive in different environmental conditions. To humans, these organisms are paramount because the majority of human infections are caused by them. Sometimes, certain bacteria are considered as parasites.

CONTENTS

1. Overview and Key Difference
2. What is a Parasite 
3. What are Bacteria
4. Similarities Between Parasite and Bacteria
5. Side by Side Comparison – Parasite vs Bacteria in Tabular Form
6. Summary

What is a Parasite?

Parasitism is a form of symbiotic association in which parasite get benefits while harming the host. Thus, parasites cause infections to the host species. If an organism lives in or on a host while obtaining nutrients from the host, that organism is defined as a parasite. Parasites can be multicellular or unicellular and are usually smaller than their hosts. Examples of unicellular parasites include various bacteria and fungi species, and that of multicellular organisms include ticks, lice, and certain worms (Helminthes).

The main characteristics of parasites are as follows:

• Undergoing simple and complex life cycles
• Involving two or more hosts
• Showing both sexual and asexual reproduction alternatively

Based on the living place, there are two types of parasites; endoparasites and ectoparasites. Endoparasites live inside the body of their host, and ectoparasites live on the outer surface or in the superficial tissues of the hosts. Hosts are two types; (a) definitive hosts, where sexual reproduction of parasite occurs, and (b) intermediate host, where asexual reproduction of the parasite takes place.

What are Bacteria?

Bacteria are primitive microscopic unicellular prokaryotes with great diversity. The first bacterial cells appeared about 3.5 billion years ago. Since bacterial species show great species diversity, they live in almost all the habitats (even in some extreme living conditions) on earth. Bacteria do not have an organized nucleus. Furthermore, they have one chromosome composed of DNA. Moreover, bacterial cells do not contain membrane-bound organelles such as endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, micro-filaments, microtubules, and centrosomes. In addition, bacterial cell wall contains a unique substance called peptidoglycan, which is polymer.

When considering the shapes of bacteria, they exhibit three basic shapes: bacillus, coccus, and spirillum. Many bacterial cells possess different types of appendages including flagella and pili, which aid them in locomotion. Gram staining is the most commonly used technique to identify bacteria. According to this stain, bacteria can be either gram-positive or gram-negative. Binary fission is the main mode of asexual reproduction seen in bacteria.

Bacteria are vital organisms to human as some of them cause diseases to human beings and some provide benefits such as nitrogen fixation, genetic engineering, decomposition, and bioremediation, etc. Some examples of disease-causing bacteria are Vibrio cholera, Corynebacterium diphtheria, Helicobacter pylori, and Rickettsia Typhi. Some bacterial diseases are cholera, diphtheria, peptic ulcers, and typhus, etc.

What are the Similarities Between Parasite and Bacteria?

• Some bacterial species are considered as parasites.
• Therefore, both parasite and pathogenic bacteria cause diseases in human, other animals and plants.
• Both groups include microscopic organisms.
• Moreover, both groups include unicellular organisms.
• They are present in many different types of habitats.
• Parasites and some bacteria live in a symbiotic relationship with another organism.

What is the Difference Between Parasite and Bacteria?

A parasite is an organism that lives in another organism called the host. In contrast, bacteria are tiny organisms that are prokaryotic and ubiquitous. Thus, this is the key difference between parasite and bacteria. When considering their cellular organization, parasites can be either unicellular or multicellular while all bacteria are unicellular, This is another difference between parasite and bacteria. Moreover, all parasites harm their host and derive nutrients from their hosts while most bacteria are harmless.

The below infographic summarizes the difference between parasite and bacteria.

Summary – Parasite vs Bacteria

A parasite is an organism that lives on or inside another organism, deriving nutrients and harming the host. In contrast, bacteria are prokaryotic unicellular microscopic organisms present everywhere. Thus, this is the key difference between parasite and bacteria. Parasites always harm their hosts while some bacteria cause harm or diseases. Furthermore, some parasites are not microscopic. Moreover, some of them are eukaryotic and multicellular. This summarizes the difference between parasite and bacteria.

Reference:

1. Brazier, Yvette. “Bacteria: What You Need to Know.” Medical News Today, MediLexicon International, 12 Feb. 2019, Available here.
2. “CDC – Parasites – About Parasites.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, Available here.

Image Courtesy:

1. “Menacanthus-chewing-louse-2” by Alan R Walker – Own work. (CC BY-SA 3.0) via Wikimedia Commons 
2. “E. coli Bacteria (7316101966)” by NIAID – E. coli Bacteria. (CC BY 2.0) via Wikimedia Commons