Gérmenes
Microbes
Revisado por pares por Dr Colin Tidy, MRCGPÚltima actualización por Dra. Toni Hazell, MRCGPLast updated 26 Mar 2023
Cumple con las directrices editoriales
- DescargarDescargar
- Compartir
- Language
- Discusión
- Versión en audio
En esta serie:AntibióticosBetalactamasas de espectro extendido
Este folleto ofrece una visión general de los diferentes tipos de gérmenes (microbios) que pueden causar infecciones.
En este artículo:
Video picks for Otras infecciones
Continúa leyendo abajo
What are germs?
Healthcare professionals classify 'germs' (microbes) into different groups. The most common groups of microbes that cause illness are described below.
Types of germs
Volver al contenidoBacterias
There are many different types of bacteria. Some bacteria are good and are helpful and protective to humans. Some flourish naturally in our bodies - particularly in the bowel and vagina - and help to protect the body from infections. However, infections with certain bacteria can cause serious illnesses such as meningitis, neumonía, tuberculosis, etc. A bacterial infection may be treated with a course of antibiotic medication.
Virus
These are smaller and different to bacteria. Many different types exist. Most of the common 'minor' illnesses are caused by viruses. For example, resfriados, tos, dolor de garganta, virus de la varicela and some other rashes. Most common infections in the community are due to a viral infection.
Viral infections are much more common than bacterial and fungal infections.
For many viral infections there are no effective antiviral medicines (unlike antibiotics for bacteria). Fortunately, the immune system in the body usually fights off most viral infections within a few days. Taking 'symptomatic' treatments for a high temperature (fiebre) or catarrh, such as paracetamol y/o ibuprofeno, resting and drinking plenty are usually all that needs to be done to get better.
There are some antiviral medicines that are used for certain infections - such as antiretroviral medicines used to treat el VIH. Another example is aciclovir and related medicines which are used to treat certain herpes virus infections including shingles. As a rule, antiviral medicines do not clear the virus from the body. They usually work by stopping the virus from multiplying and so 'control' the virus and the infection that it causes.
Hongos
Many types of fungi exist and cause problems in humans, animals and plants. Fungal infections commonly affect the skin and nails in humans. They can cause tiña, pie de atleta, other localised skin rashes y infections in and around nails. Modern creams usually work well to clear a local fungal rash quickly. However, nail infections can be rather stubborn and may need long-term treatment of antifungal medicines taken by mouth.
Most fungi are free-living in the environment and few of these are capable of causing infection in an otherwise healthy person. However, they can cause serious infections in patients with weakened immune systems (for example, those who have recently received chemotherapy for cancer).
Yeasts
Yeasts are actually a type of fungus. There are different yeasts which cause various infections. The most common yeast infection is thrush. This is due to a yeast called candida which thrives in moist, airless, warm areas of the body. It can cause infections in the vagina y infections in the mouth. It can cause nappy rash in babies and it can also sometimes infect other areas of the body. Treatment of yeast infections usually works well with anti-yeast creams and medicines.
Parásitos
A parasite is a type of germ that needs to live on or in another living being (host) to survive. It gets its food from its host.
Parasites are usually found in contaminated food or water. They can also get into the body by insect bites or by sexual contact. Parasitic infections are more common in the tropics and subtropics. They can occur in the UK but the serious infections are more typically seen in people who have weakened immune systems (for example, those with el VIH or those people taking chemotherapy for cáncer).
Examples of diseases caused by parasites are malaria, amoebic dysentery y giardia. Oxiuros, hookworms and tapeworms are also parasites.
Continúa leyendo abajo
What do germs look like?
Volver al contenidoGerms cannot be seen by the naked eye - you would need a microscope to look at them. This picture is taken down the microscope - it is of the bacterium called Staphylococcus aureus which often causes skin infections.
Staphylococcus aureus

© Content Providers(s):CDC/Matthew J. Arduino, DRPH Photo Credit:Janice Haney Carr, Public domain, via Wikimedia Commons
How do germs spread?
Volver al contenidoGerms can spread by contact between people and sometimes on surfaces such as door handles. It is therefore very important that you wash your hands after going to the toilet and after coughing or sneezing if you have a cold.
How long do germs live on surfaces?
This can vary from a few hours to several months, depending on which type of germ it is.
Continúa leyendo abajo
How to prevent infections from germs
Volver al contenidoThe best way to prevent infections is by simple hygiene methods such as regular hand-washing, using a tissue if you cough or sneeze, and staying at home and avoiding close contact with others if you are ill, particularly if you have an illness with vomiting or diarrhoea.
Can germs be killed by a medicine?
Volver al contenidoTreating bacterial infections and parasites
As mentioned, most common infections are caused by viruses when an antibiotic will not be of use. Even if you have a bacterial infection, the immune system can clear most bacterial infections. This means that antibiotics are not usually needed for minor infections (for example, an ear or throat infection in an otherwise fit person). The throat infection sometimes known as 'strep throat' is a good example of a bacterial infection which usually gets better by itself. However, you do need antibiotics if you have certain serious infections caused by bacteria, such as meningitis, urinary tract infections, pneumonia or kidney infections.
Antibiotics can kill off normal 'defence' bacteria which live in the bowel and vagina. This may then allow other infections - for example, thrush - to develop.Overuse of antibiotics has led to some bacteria mutating and becoming resistant to some antibiotics which may then not work when really needed. For example, meticillin-resistant Staphylococcus aureus (MRSA) is a bacterium that has become resistant to many different antibiotics and is often very difficult to treat.
Another example is some bacteria produce chemicals called enzymes such as extended-spectrum beta-lactamases (ESBLs), which make them resistant to some antibiotics. The more antibiotics are used, the greater the problem of antibiotic resistance.When antibiotics are appropriately prescribed, it is important to take them as directed on your prescription and to complete the full course of treatment.
Treating viral infections
Doctors are skilled in diagnosing which conditions are in need of antibiotics. So do not be surprised if a doctor does not recommend an antibiotic for conditions caused by viruses or non-bacterial infections, or even for a mild bacterial infection. Most simple coughs, colds, sore throats and influenza are caused by viruses and an antibiotic will not work. For some viral infections you are more likely to be harmed by the side-effects of an antibiotic than to benefit from it.
Occasionally, a viral infection or minor bacterial infection develops into a more serious 'secondary' bacterial infection. You should see a doctor to review the situation if an illness appears to change, becomes worse, does not go in the expected time-frame, or if you are worried about any new symptom that develops.
Treating infections from fungi and yeasts
Antibiotics will only clear infections caused by germs such as bacteria and some parasites. They do reportado work when an infection is caused by viruses, fungi or yeasts.
Antibiotics are not a 'cure all' for infections. Antibiotics can cause side-effects such as allergies, diarrea, rashes and nausea. Side-effects are quite common. Most side-effects are not serious, but some people have died from a severe allergic reaction to an antibiotic.
See the separate leaflet called Antibiotics for more information.
Patient picks for Otras infecciones

Infecciones
Listeria
La listeriosis es una infección rara causada por un tipo de germen (bacteria) llamado listeria. Por lo general, provoca una enfermedad leve que no requiere tratamiento. Sin embargo, puede causar una enfermedad grave, especialmente en personas mayores y en personas con un sistema inmunológico débil. La infección durante el embarazo también puede causar una enfermedad severa en el bebé no nacido.
by Dr Hayley Willacy, FRCGP

Infecciones
MRSA
Infection with MRSA bacteria mainly occurs in people who are already ill in hospital. It can be difficult to treat MRSA, as the bacteria are resistant to most types of antibiotic medicines. Many people are carriers of MRSA without even realising it, as MRSA often does not cause symptoms in healthy people.
por la Dra. Toni Hazell, MRCGP
Lecturas adicionales y referencias
- Antimicrobial Resistance (AMR): information and resources; GOV.UK, updated September 2025
- Health protection, Infectious Diseases; GOV.UK
- Antibiotic Resistance. Fact Sheet; World Health Organization, November 2017
- Kramer A, Schwebke I, Kampf G; How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infect Dis. 2006 Aug 16;6:130. doi: 10.1186/1471-2334-6-130.
Continúa leyendo abajo
Historial del artículo
La información en esta página está escrita y revisada por pares por clínicos calificados.
Próxima revisión: 24 Mar 2028
26 Mar 2023 | Última versión

Pregunta, comparte, conecta.
Navega por discusiones, haz preguntas y comparte experiencias en cientos de temas de salud.

¿Te sientes mal?
Evalúa tus síntomas en línea de forma gratuita
Suscríbete al boletín de Patient
Tu dosis semanal de consejos de salud claros y confiables, escritos para ayudarte a sentirte informado, seguro y en control.
By subscribing you accept our Política de Privacidad. Puedes darte de baja en cualquier momento. Nunca vendemos tus datos.