For anyone who has taken University level microbiology classes, this diary will be about things you already know. For everyone else, this is an important diary for two reasons. It will help you prevent the food you have from spoiling (thus more food for you). And it will help, if by chance, you need to care for an open wound.
Aseptic technique is the first thing we were taught in my undergraduate Microbiology 101 lab class 25 years ago.
The first rule is to be aware of anything that touches or comes in direct physical contact with anything else. In the microbiology lab, we would mix up the food ingredients for bugs in a large Erlenmeyer flask, add agar (a gel derived from seaweed to make it semi solid), place that into the autoclave sterilizer (15 psi steam at 121 C for 15 minutes) to kill all the microbes, then pour it into sterile petri plates (circular plastic dishes about 10-30 cm wide and ~1-2 cm deep). We would keep those for months sealed in bags in a fridge until we needed them for an experiment.
Usually nothing would grow in them since we had prevented them from contacting anything after they were sterilized. Occasionally you would find a single petri plate with a fungal colony thriving and you would throw it into the biohazard bag for sterilization and safe disposal.
Photo of a petri plate here
There is a story about how a Scientist named Alexander Fleming discovered penicillin when a fungal spore floated through his window and landed on one of his culture plates. Personally I don't believe it. I think he was a sloppy but observant Scientist who allowed his experiments to be ruined and then, to salvage something of it, he wrote a paper and mentioned the two different microorganisms competing with each other on his contaminated plate. It took a lot of other Scientists to determine that it was an important discovery and to identify and then manufacture penicillin. Flemming just wrote a paper with an interesting aside about a contaminated petri plate.
Sorry for the diversion, back to the topic.
When I empty the dishwasher, I never touch the blade of a knife, fork or spoon. I only touch the handles of my cutlery. Similarly, I never touch the inside of a storage container (tupperware, casserole dish etc). That's because these things come in contact with the food we store. The cutlery touches the insides of jam jars etc. To touch the working ends of these items would transfer microorganisms and thus contaminate our food. I never touch a block of cheese I will not eat in full that day with my fingers. I avoid contact between my fingers and any food, or anything that contacts that food if I want to preserve it for future leftovers. I am very careful to open lids of foodstuffs without contaminating them. I always place the lid face up on the counter and quickly retrieve what I need before recapping.
Aseptic technique is basically avoiding any direct contact and minimizing exposure of foodstuffs you want to preserve from any source of contamination by microorganisms.
All the same lessons apply in medical situations. If someone has an open wound. Avoid touching anything that comes in contact with it. Avoid sneezing and coughing. ~30% of all infections treated in hospital are acquired in hospitals. Hospitals are ground zero for infectious organisms. Drug resistant ones too.
If you are aware of aseptic technique, your food will last longer and your family will have fewer infections. There is no need to obsess or be overly anal about it, but minimizing needless opportunities for microbial growth will help you live a healthy and happy life.
Just remember, we are but temporary visitors on this planet. The microbes own this place.