I had the opportunity along with my biology class to participate in a microbiology experiment at the University of Regina. This experiment involved gathering samples of bacteria from various surfaces and attempting to grow or ‘culture’ these bacteria by spreading a bacteria covered surface onto an agar plate. We first gather the bacteria by swabbing or brushing a swab against a bacteria covered surface.
After gathering bacteria we then spread the bacteria onto an agar plate- we used three types of agar plates including: MacConkey, Mannitol Salt, and Lysogeny Broth (LB) plates. These different plates all had different purposes; the LB plates were simply a plate which most bacteria could grow on, however the MacConkey and Mannitol Salt plates are selective. This means that the medium found within the plates will kill off certain varieties of bacteria while letting others live. In this case, the MacConkey selected for gram negative microbes, while also producing a colour change to allow differentiation between lactose metabolizing bacteria. The Mannitol Salt plates also selected for gram positive microbes.
During the experiment I specifically sampled several surfaces, from ATM machines and water fountains to my hands and even my nose. I also used several agar plates in conjunction with these samples. I used all three plates described earlier and tried to display different varieties of bacteria by spreading the same samples on different plates, like spreading my ATM and water fountain samples over all three plates to select for gram positives and negatives between plates. After a brief period of incubation at human body temperature the plates were ready to observe. My plates featured little growth which could have been a result of generally clean surfaces, or the plates themselves could have selected against the bacteria on them. The incubation temperature also could have been either too warm or too cold for certain bacteria to grow, or the bacteria may have simply needed more time to grow. The nose sample plate however featured massive growth which could be caused by several types of ‘good bacteria’ naturally found in the nose.
One thing that really struck me from our experiment was the information we received regarding the ubiquity of bacteria all around us, with common areas like sponges, cutting boards and tooth-brushes being absolutely filled with bacteria.
So being constantly surrounded by bacteria, what’s one to do? Constantly disinfect every surface one might come into contact with? Live in a bubble? All of these responses are very inconvenient and would likely cause more damage than good. This is due to the fact the human immune system builds up resistances to pathogens which it has already been exposed to, so without any bacterial contact our immune systems will lack the resistances which typically protect us from bacteria. If an immune system lacks any sort of resistances it will less able to defend against various pathogens when it is eventually exposed to them. There is also a study which suggests that exposure to any kind of bacteria may help an individual build up resistances to types of bacteria they have never even been exposed to. Bacteria can also develop resistances to things like antibiotics which are designed to eliminate them. This is largely in response to the misuse of antibiotics, or the prescription of broad spectrum antibiotics as opposed to specific antibiotics. The ever increasing prescription of more potent antibiotics also contributes to bacterial resistance to higher strengths of antibiotic. Bacterial resistances to antibiotics are already said to have reached alarming levels by the World Health Organization. If bacteria can build up resistances against antibiotics I see no reason why they can’t build up resistances against common household detergents and disinfectants if these disinfectants are also misused or over used. So cleaning excessively can likely promote the creation of sterilization-resistant bacteria. This hypothesis can be further supported by the questioning of the efficacy of hand sanitizers by the FDA. Ultimately it is better to expose ourselves to common bacteria then it is to isolate ourselves, however cleaning should still be undertaken to maintain health. In general it is best to live without fear of bacteria and use reason and discretion when sanitizing and cleaning.