A total of 24 percent of surface germs were identified as gram-positive rods. Although mostly harmless, this type causes the majority of skin infections.
Just under one percent of trolleys tested positive for gram-positive cocci, which is associated with skin infections, in addition to pneumonia and blood poisoning.
And although only in trace amounts, bacillus, which is commonly linked to food poisoning was also detected, while yeast, which causes skin infections was also present.
"Like gram-negative rods, gram-positive cocci can carry parasites and pathogens harmful to humans," the report notes.
"In fact, gram-positive cocci are responsible for a third of all bacterial infections that impact humans."
• Gram-negative bacteria
Gram-negative bacteria are usually thought of as the nasty bugs that can make us sick and can be harmful. For example, several species of Escherichia coli (E. coli), are common causes of food-borne disease. Another example is Vibrio cholera, the bacteria responsible for cholera, is a waterborne pathogen. According to the Ministry of Health, cholera is not endemic in New Zealand.
• Gram-positive bacteria
Usually, gram-positive bacteria are the helpful, probiotic bacteria we hear about that live in our gut and help us digests food. But there are different types. Although mostly harmless, they also cause the majority of skin infections.
• Gram-positive cocci
Staphylococcal is the most worrying type. It can cause a wide range of infections, from relatively minor skin infections such as boils, to more serious infections of the blood, lungs and heart.
There are many types of Staphylococci, but most infections are caused by a group called Staphylococcus aureus. This group of bacteria includes meticillin-resistant Staphylococcus aureus (MRSA), which is resistant to certain antibiotics.
A type of gram-positive bacteria, bacillus is commonly linked to food poisoning. These toxins can cause two types of illness: one type brings on diarrhoea and the other, called emetic toxin, nausea and vomiting.