General safety in the laboratory Pasteur Institute TPHCM

I.Introduction Hồ Chí Minh city Pasteur institute is established 1891 by the idea of Louis Pasteur For a century, there were many changes in policy and history; the main duties of Pasteur institute are research on microbiology, molecular biology, infection diseases, vaccines and checking the quality of safety and hygiene of food products, etc Food is the main resource of nutrition for human so that safety and hygiene is very important for human consumption Therefore, our country has standards (TCVN) for ensuring the quality of food in the market But it cannot manage all the prolems on food borne diseases which are become more complecate One of the troubles is the infection of micobiology The microorganism such as Staphylococcus aureus in hand made food, Clostridium perfringens in the pre heat many times food, and Listeria in frozen raw meat and cooked meat make disease for the consumers To prevent those problems the customers should choose the food having clear resource, wash hand before meal, eat at clean places, and keep food at safe temperatures In Pasteur institute, the food microbiology isolation and indentification helps the manufactures and consumers to check pathogenic microorganism in their food products II.The necessary regulation in microorganism testing room There is a certain element of risk in anything you do, but the potential risks in a microbiology course are greater Persons who work in a microbiology lab may handle infectious agents in additional to other hazards such as chemicals and radioactive materials There have been many documented cases of lab personnel acquiring diseases due to their work About 20% of these cases have been attributed to a specific incident, while the rest have been attributed to work practices in the lab The rules must be followed:  Wash your hands with disinfectant soap when you arrive at the lab and again before you leave  Absolutely no food, drinks, chewing gum, or smoking is allowed in the laboratory Do not put anything in your mouth such as pencils, pens, labels, or fingers Do not store food in areas where microorganisms are stored  Purchase a lab coat and safety glasses, bring them to class, and use them Alternatively, a long sleeved shirt that buttons or snaps closed is acceptable protective clothing This garment must cover your arms and be able to be removed without pulling it over your head Leave protective clothing in the lab and not wear it to other non-lab areas  Avoid loose fitting items of clothing Wear appropriate shoes (sandals are not allowed) in the laboratory  Keep your workspace free of all unnecessary materials Backpacks, purses, and coats should be placed in the cubbyholes by the front door of the lab Place needed items on the floor near your feet, but not in the aisle  Disinfect work areas before and after use with 70% ethanol or fresh 10% bleach Laboratory equipment and work surfaces should be decontaminated with an appropriate disinfectant on a routine basis, and especially after spills, splashes, or other contamination  Label everything clearly  Replace caps on reagents, solution bottles, and bacterial cultures Do not open Petri dishes in the lab unless absolutely necessary  Inoculating loops and needles should be flame sterilized in a Bunsen burner before you lay them down  Turn off Bunsen burners when not is use Long hair must be restrained if Bunsen burners are in use  When you flame sterilize with alcohol, be sure that you not have any papers under you  Treat all microorganisms as potential pathogens Use appropriate care and not take cultures out of the laboratory  Wear disposable gloves when working with potentially infectious microbes or samples (e.g., sewage) If you are working with a sample that may contain a pathogen, then be extremely careful to use good bacteriological technique  Sterilize equipment and materials  Never pipette by mouth Use a pipetting aid or adjustable volume pipettors In the distant past, some lab personnel were taught to mouth pipette This practice has been known to result in many laboratory-acquired infections With the availability of mechanical pipetting devices, mouth pipetting is strictly prohibited  Consider everything a biohazard Do not pour anything down the sink Autoclave liquids and broth cultures need to sterilize them before discarding  Dispose of all solid waste material in a biohazard bag and autoclave it before discarding in the regular trash  Familiarize yourself with the location of safety equipment in the lab (e.g., eyewash station, shower, sinks, fire extinguisher, biological safety cabinet, first aid kit, emergency gas valve) III.Isolation and identification process of some bacteria Aerobic bacteria The first step is homogenized sample step Using pasteurized equipment to balance exactly 25g of food sample into PE bag Then adding 225mL of peptone water solution Food sample were homogenized by stomacher machine The maximum period of homogenized process is 2.5 minute It is depended on the physicalmechanical characteristics of food sample After homogenized process, the food sample has concentration at 10-1 Homogenized mixture is continued to dilute in to 10-2, 10-3, etc Using pasteurized pipet move 1mL mixture into test-tube that contained 9mL saline solution inside Then using the vortex machine to mix the solution in the test-tube This solution has concentration at 10-2 After that continue with concentration at 10-3, 10-4 so on until the solution reach to required concentration Noting that the heads of pipet are very easy to be infected, during the process if having any risk such as it tough with human hand, outside surface of test-tube, etc they need to be replaced by another Choosing two or three continuous concentration that contain from 25 to 250 bacteria cells per 1mL Sample solution is move to pasteurized petri dish by pasteurized pipet Each concentration will be inoculated at least two or three time Then pour into each dish 10-15mL of PCA agar has been melted and stable at 450C Sample solution and medium by gyrated dishes clockwise and anti-clockwise These dish will be put on the horizontal surface for the solidify of agar occur Then all of dish will be incubated at 300C±10C for 72 hours After incubate, all colonies growth on the agar plate will be counted The dishes will be chosen to count if they have total amount of colonies from 25 to 250 The total density of aerobic in 1g or 1mL will be calculated by: ( ⁄ ⁄ ) Where: A: the number of bacteria cells in 1g or 1mL of sample N: total number of colonies growth on dishes has been chosen : number of dishes has been inoculate at concentration i : concentration of sample V: volume of sample solution has been inoculated in each dish Result of total number aerobic bacteria usually represent at form of decimal exponent If at highest concentration, the total number of colonies larger than 250, for example at 10-5 has more than 250 colonies, the result will be >2.5×107 CFU/g If at lowest concentration, the total number of colonies smaller than 25, the result will be