Human diseases caused by bacteria

Turning attention to bacterial pathogens, of all the known bacterial organisms, very few of them are pathogenic to humans causing bacterial diseases. Human diseases caused by bacteria (bacterial diseases) have different modes of transmission based on which the classification of bacterial diseases is done. Let’s go on a journey of examples of bacterial diseases and their causal organisms. The mode of transmission is variable and they can be classified accordingly.

Airborne Diseases:

Firstly, let’s throw some light on airborne diseases. In this case, the mode of transmission of bacterial diseases is via air. The chief site of action for these types of bacterial diseases is the human respiratory system. But other parts like the skin can also be affected. So, let’s have a look at a few examples.

  • Chlamydial Pneumonia is caused by Chlamydophila pneumoniae.
  • Diphtheria is caused by Corynebacterium diphtheriae.
  • Legionnaires’ Disease (also called Legionellosis) is caused by Legionella pneumophila. 
  • Meningitis is caused by Streptococcus pneumonia, Neisseria meningitidis, Haemophilus influenzae serotype b, Nocardia asteroides, Staphylococcus aureus, Mycobacterium tuberculosis, Listeria monocytogenes, and Group B streptococci. 
  • Tuberculosis (TB) is caused by Mycobacterium tuberculosis.
  • Mycoplasmal Pneumonia is caused by Mycoplasma pneumoniae.
  • Pertussis is caused by Bordetella pertussis.
  • Streptococcal Pharyngitis is caused by Group A Streptococci.

Also read – Are Prions infectious agents? – My Biology Dictionary

Human diseases caused by bacteria


Direct Contact Bacterial Diseases:

Second of all, in this case, the mode of transmission of bacterial diseases is direct contact and this usually involves skin transmission. As a matter of fact, this category also includes sexually transmitted diseases (STDs). So, let’s have a look at the examples:

  • Leprosy is caused by Mycobacterium leprae.
  • Tattoo-associated Mycobacterial Infection is caused by Mycobacterium chelonae.
  • Gas Gangrene (also called Clostridial Myonecrosis) is caused by Clostridium perfringens. 
  • Group B Streptococcal Disease (GBS) is caused by Streptococcus agalactiae. 
  • Peptic Ulcer Disease is caused by Helicobacter pylori.
  • Nongonococcal Urethritis is caused by Neisseria gonorrhoeae.
  • Staphylococcus Scalded Skin Syndrome (SSSS) is caused by Staphylococcus aureus. 
  • Tetanus is caused by Clostridium tetani.
  • Trachoma is caused by Chlamydia trachomatis.
  • Ophthalmia neonatorum is caused by Neisseria gonorrhoeae (when the birth canal is infected).
Human diseases caused by bacteria


STDs (sexually transmitted diseases caused by bacteria):
  • Gonorrhea is caused by Neisseria gonorrhoeae.
  • Syphilis is caused by Treponema pallidum subsp. pallidum.
  • Chancroid is caused by Haemophilus ducreyi.
  • Granuloma Inguinale is caused by Calymmatobacterium granulomatis.
  • Urethritis is caused by Ureaplasma urealyticum.
  • Nongonococcal urethritis (NGU), Cervicitis, Pelvic Inflammatory Disease (PID) is caused by Chlamydia trachomatis.
Human diseases caused by bacteria


Food-Water Borne Bacterial Diseases:

In this case, the mode of transmission of bacterial diseases is via the intake of food and water and food poisoning comes into the picture because food could be the source of the pathogen. So, let’s have a look at a few examples.

  • Cholera is caused by Vibrio cholerae.
  • Salmonellosis (also called Salmonella gastroenteritis) is caused by 2000 Salmonella serovars.
  • Sepsis and Septic Shock is caused by E. coli, Klebsiella spp., Enterobacter spp., Salmonella spp. etc.
  • Shigellosis is caused by four species of Shigella like S. sonnei.
  • Gastroenteritis is caused by Campylobacter jejuni. 
  • Food-borne Botulism is caused by Clostridium botulinum.
  • Escherichia coli Gastroenteritis is caused by Escherichia coli. There are about six strains of E.coli that are diarrheagenic. Despite being a part of normal microflora, it can serve as a pathogen. They are: Enterotoxigenic E. coli (ETEC), Enteropathogenic E.coli (EPEC), Enteroaggregative E.coli (EAggEC), Enteroinvasive E.coli (EIEC), Enterohemorrhagic E.coli (EHEC), Diffusely Ahdering E.coli (DAEC). 

Arthropod-Borne Bacterial Diseases:

Here bacterial diseases are spread because of arthropods. Not much is known about this category because this mode of transmission is rare.

  • Lyme Disease (LD, also called Lyme Borreliosis) is caused by Borrelia burgdorferi, Borrelia garinii, Borrelia afzelii. 
  • Plague is caused by Yersinia pestis.
  • Rocky Mountain Spotted Fever is caused by Rickettsia rickettsii.

Zoonotic Bacterial Diseases:

Zoonoses or Zoonotic Bacterial Diseases is a term used to denote the transmission of bacterial diseases through animals. So, let’s have a look at the examples of Zoonoses.

  • Anthrax is caused by Bacillus anthracis. 
  • Brucellosis is caused by Brucella species and examples of species are- B. abortus, B. melitensis, B. suis, B. canis. 
  • Psittacosis (also called ornithosis) is caused by Chlamydophila psittaci. 
  • Q Fever is caused by Coxiella burnetii.
  • Tularemia is caused by Francisella tularensis.

Opportunistic Bacterial Diseases:

In contrast to other types, it is a specialised category of bacterial diseases where the normal microbiota of the human body can particularly become pathogenic in certain cases. So, let’s have a look at a few examples.

  • Antibiotic-Associated Colitis is caused by Clostridium difficile.  
  • Bacterial Vaginosis is caused by Gardnerella vaginalis. 
  • Streptococcal Pneumonia is caused by Streptococcus pneumoniae. 

Such a variety of modes of transmission subsequently opens up doors for more research in the field of medicine. Undoubtedly, bacterial populations are constantly evolving against antibiotics, therefore, there is a need to dig in deeper for better cures and solutions to these bacterial diseases. We have covered a handful of examples for you but the story doesn’t end here, keep reading for more.

Team MBD

Learn more about bacterial diseases- Bacterial Infections: MedlinePlus

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  1. thanks after sharing

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