Common Germs

Introduction

Any germ can become a pathogen (a germ that causes harm to the body) if it is in the wrong body site, or in the right amount.  It takes a minimal amount of germs to cause an infection.  This amount is different for each germ and each person. 

Bacteria

Bacteria are single celled organisms that can reproduce quickly.  Some cause disease and harm the body, but others are beneficial and cause no harm.  Some bacteria are easily killed with chemicals, while some reproduce by creating spores (that have a protective capsule around the cells) and are extremely difficult to kill.

Vaccines are available for some specific bacteria: Pneumococcus, tetanus, and diptheria.

Staphylococcus

or Staph is commonly found in the soil, dirty surfaces, on human skin, and in the intestinal tract of healthy people.  Some Staph can cause serious infections, especially the Staph aureus group.  These can live up to three weeks on a dry surface and may cause skin and surgery infections, food poisoning, pneumonia etc.  Some Staph aureus may be resistant to many antibiotics and are called methicillin-resistant Staph aureus (MRSA) (See MRSA Fact Sheet for more information).  When food contains Staph germs, vomitting is the primary symptom and may occur within 1-3 hours.  Cooking the food will not prevent illness because it is caused by a toxin released by the cell wall of the bacteria.

Streptococcus

or Strep is found in water, soil, vegetation.  Strep is often the cause of skin infections, sore throat, sinus infections, bronchitis, pneumonia, meningitis, and heart valve infections.  There are many Strep family members, but the most common is Strep pneumoniae (lung infections).  One of the most serious is Strep pyogenes, also called Group A Strep, that causes 'Strep throat' and other infections like scarlet fever.  Untreated Group A Strep can lead to rheumatic fever or affect the kidneys.

Salmonella

is a common form of food poisoning and blood infections.  Salmonella bacteria can be found in contaminated milk and dairy products, water, reptiles, raw chicken, fish and pork.  Typhoid fever is caused by the Salmonella typhi family member.

Escherichia coli or E. coli

E. coli species are bacteria widely seen in water and soil, and in the human intestinal system.  It is a common cause of bladder infections, wound infections (gall bladder, appendix, colon cancer surgery), food poisoning, and traveller's diahorrea.  The presence of E. coli in drinking water usually indicates sewage contamination.

Mycobacterium tuberculosis or TB

is found in the soil and in water.  It is much more durable and harder to kill than most bacteria.  TB and several other mycobacteria family members can cause infection in the lung, throat, brain, skin or bone.

Clostridium difficile or C diff

are bacteria found in the colon of many healthy adults.  When antibiotics are given for an extended period of time, the normal bacteria are killed off in the intestines.  This may allow C diff to florish and the patient can develop severe diarrhoea.  It is a very hardy germ and can survive in the environment as a spore for lengthy periods of time.  Cleaning the environment at home or in a health care facility is very important to reduce the risk of transmission.

Viruses

Viruses are very small organisms that infect living cells of man and animals.  Viruses can only reproduce by invading and taking over other cells.  Many cause harm to the body and are not killed by antibiotics.  Some viruses become dormant in the body for long periods of time and do not cause disease.

Common viral infections include: Hepatitis A, B, C; HIV, measles, mumps, chickenpox (and shingles), herpes simplex, influenza (flu), norovirus.  Many upper respiratory infections (colds) are caused by viruses, not bacteria, so antibiotics are useless as a cold treatment.  Sometimes your doctor may recommend antibiotics if he believes you have a secondary infection caused by bacteria after having the flu.

Vaccines are available to prevent hepatitis A, B, chickenpox, measles, mumps, rubella, and influenza.  The immunity obtained from the vaccines varies with the person and type of vaccine.  The Flu vaccine is recommended to be given each year.

Fungi

Fungi are a group of plant-like organisms that live and feed on other organisms.  Yeast and mould are two types of fungi.  Yeast and other types of fungi are found in the soil and air when the soil is disturbed.  When normal bacteria are killed off at a specific body site, yeast will over-grow the site.  For example, normal bacteria in the mouth are reduced from long-term antibiotic use in immuno-suppressed patients.  Thrush (candidiasis) is a yeast that will commonly grow on the tongue and inside the mouth. When immuno-suppressed patients develop a serious fungal infection such as pneumonia, the fungi can travel to other organs such as the blood, brain, spinal fluid, and throughout the entire body.

Parasites

A parasite is an organism that lives on or feeds on the living tissue of another organism.  They give no benefit to the host, but depend on the host for survival.  Parasites can be transmitted during contact with someone who is infected, or found in contaminated water.

Common parasites include: lice, tapeworm, mites, and scabies.

Good Germs

There are many bacteria, fungi and parasites that are helpful to man.  Just like good germs help to change milk to cheese, good germs inside the body help to digest what we need to eat and keep us in working order.  There are a large variety of germs in our mouths, stomach, colon, and even on our skin.  To remain healthy it is necessary for these germs to be there but to be controlled.

References:

Prevent Infection website
www.preventinfection.org

Better Health Channel
www.betterhealth.vic.gov.au