Which are the main diseases due to bacteria?

A substantial number of infections are caused by species of bacteria that are present on or in many people without producing disease.

A substantial number of infections are caused by species of bacteria that are present on or in many people without producing disease. Very often, these bacteria only become pathogenic when they end up in a place where they are not supposed to be, or when their numbers have increased unduly due to a weakening of the immune system. There are however also strains of bacteria that always cause disease, such as the enterohemorrhagic strains of Escherichia coli bacteria.

The bacteria responsible for the most common conditions

Streptococcus pneumoniae. Often referred to as “pneumococci”, these bacteria are normally present in the nose and pharynx of many people without causing any infection. It is therefore the healthy carriers in the population who transmit the bacteria to the elderly, children or other susceptible people, among whom serious disease may then occur. In Switzerland, pneumococci cause around one thousand serious infections (in the bloodstream or as meningitis) each year, as well as several thousand cases of pneumonia. These bacteria are also responsible for many self-resolving infections, including bronchitis and ear infections.  

Staphylococcus aureus is present as part of skin flora in around one third of the human population, without causing disease. Depending on the strain and the immune system of the infected person, S. aureus can infect the skin, bone and soft tissue inside the body, including the bloodstream. In hospitals, it is the most frequent cause of post-surgical infections. In animal husbandry, it can trigger various infections, particularly in the udders of dairy cows (mastitis).  

Escherichia coli is an enterobacterium that lives in the intestines of humans and animals without causing disease. It is even useful and forms part of the normal intestinal flora of healthy individuals. But it can cause infections if it goes somewhere else in the body, such as the lower urinary tract, the abdomen or the brain in the case of new-borns. Certain pathogenic strains of E. coli (for example the toxin-producing O157:H7) are known to pass from animals to humans through food products. In humans, such bacteria can lead to fever, nausea, vomiting, stomach cramps and diarrhoea, which can be fatal in some cases.  

Klebsiella pneumoniae is another species of enterobacterium commonly present in the digestive tract of healthy humans and animals. It is nevertheless one of the most common culprits for causing hospital-associated infections as well as urinary tract and respiratory tract infections, especially pneumonia. In new-borns, Klebsiella pneumoniae can infect the bloodstream, leading to increased mortality rates. This type of bacteria also has the ability to easily acquire multiple forms of antibiotic resistance.
Also worth a mention are Acinetobacter baumannii and Pseudomonas aeruginosa, which are among the so-called hospital pathogens, because they mainly produce infections within hospitals and care home. Resistance of these two bacterial species to last-resort antibiotics such as carbapenems and polymyxins is increasing, nationally and globally.

The main reportable diseases

In Switzerland, a compulsory reporting system enables doctors and laboratories to declare certain infectious diseases to each canton’s Chief Medical Officer or to the Federal Office of Public Health (FOPH). This reporting allows early detection of potential public health problems, and therefore also early preventive measures if necessary. There are over 40 different diseases on the list of reportable diseases.   

For bacterial infections that are reportable, the numbers of annually reported cases shown below are estimates based on the average of the three previous years.   

Bacterial agents transmitted by the respiratory route

  • Pneumococci: invasive diseases, around 900 reported cases per year.
  • Tuberculosis: around 500 reported cases per year.
  • Legionella: around 400 reported cases per year.
  • Haemophilus influenzae (a type of bacteria that has nothing to do with the virus responsible for the flu): invasive diseases, around 100 reported cases per year.
  • Meningococci: invasive diseases, around 50 reported cases per year.  

Bacterial agents transmitted by the oral route

  • Campylobacter: around 7,500 reported cases per year.
  • Salmonella: around 1,500 reported cases per year.
  • Infections with enterohemorrhagic E. coli : around 600 reported cases per year.
  • Shigella: around 150 reported cases per year.
  • Listeria: around 50 reported cases per year.
  • Typhoid and paratyphoid fever (S. typhi, S. paratyphi): around 20 reported cases per year.  

Bacterial agents transmitted by the sexual or contaminated blood route

  • Chlamydia: around 11,000 reported cases per year.
  • Gonorrhoea: around 2,400 reported cases per year.
  • Syphilis: around 1,000 reported cases per year.  

Bacterial agents transmitted by animals

  • Lyme disease (borreliosis): around 10,000 reported cases per year.
  • Tularaemia: around 80 reported cases per year.
  • Brucellosis: fewer than 10 reported cases per year.

Last modification 15.10.2018

Top of page

Contact

Federal Office of Public Health FOPH
Communicable Diseases Division
Strategies, Principles and Programmes Section
Schwarzenburgstrasse 157
3003 Berne
Switzerland
Tel. +41 58 463 87 06
E-mail

Print contact

https://www.bag.admin.ch/content/bag/en/home/krankheiten/infektionskrankheiten-bekaempfen/antibiotikaresistenzen/welche-bakteriellen-krankheiten-gibt-es-.html