By Week 10, Day 3, consider the following questions: assignment 1 1. Explain what is meant by “indicator” organisms when testing a water sample. What are the media used to determine the presence of...

1. Indicator organisms are the one which is said to be used in the detection of water quality. Usually an organisms which in turn serves as a surrogate for another organisms is termed as indicator organisms. It is hence used in the detection of fecal contamination of the drinking water source. This presence of the indicator organisms helps in the detection of other disease causing agents and potential health hazards. In general E.coli can be considered as an indicator organism. They use to live longer than the pathogens, larger number in occurrence and less chance of pathogenicity during the collection and sampling. According to (Sloat and Ziel, 1992 & Thomann and Mueller, 1987) Indicator organisms shall easily detected ny simple routine tests. Generally this should not present in non polluted water. The presence of its concentration should get correlates with the level of the contamination causing organisms in the water. It must not die faster than the pathogen. The presence of E.coli can detect by MPN method. The presumptive test uses Lactose broths such as Lauryl tryptose broth / Lactose Bile broth. In confirmatory test the media used is BGLB – Brilliant Green lactose Broth. Finally in completed test the media used is Endo Agar / Eosin Methylene Blue Agar. Finally EMB Agar media is commonly selective media that is being used for the detection of E.coli; the metallic shield indicates the presence of E.coli in the given sample. The color of E.coli is identified as red, purple, yellow may be black. The shape of it is said as round, filamentous, smooth. E.coli usually basically has convex elevation. They use to grow as concentric growth rings. Biochemical characters as late lactose fermentors.
2. The three major species of staphylococcus are Staphylococcus aureus, staphylococcus epidermidis and staphylococcus saprophyticus. S.aureus is golden yellow in color, 1 micrometer in diameter, usually present in cluster and most of the strains are capsulated, Beta hemolytic in nature. S. epidermis is white color, whereas S. saprophyticus. S.aureus is more pathogenic than compared with other two. Hemolysis – a toxin (alpha), otherwise said as potent membrane damaging toxin. (Beta) toxin, damages the membranes which are rich in lipids. Coagulase and clumping factors, Staphylokinase, is a plasminogen activator enzyme which in turn lyses the fibrin. Protein A bind with IgG disrupts the process of phagocytosis. The other presence of leukocidins and exotoxins make this as more pathogenic when compared with other two. Exotoxins determine the pathogenesis of the organisms. They are found as the form of small component of the soil micro flora. Madigan, M and Martinko, J ed (2005)
Review Sheet Week 10
Exercise 11
1. In the areas of high risk such as neonatal care, ICU and operating room and outpatient area must have the increasing number of microorganisms from the environment and that should be reduced by proper cleaning with anti bacteriocytic agents.
2. Microbiologists must wear lab coats when they are inside the lab. This operon usually acts as the second skin and it protects the users in the lab. Sometimes they may be using acids and chemicals they may be toxic to humans. If they spill when they wore lab coat they can be immediately notified and the coat is removed. The white color easily detects the stains and helps to offload it. It can act as a barrier in avoiding the entry of the pathogens, hence after it should be sterilized. Hence the usage of this necessary to avoid the undesirable actions that might happen when they are inside the lab.
3. The reason for wearing the clean protective clothing while caring the patients is said as 1. You are not willing to act as a carrier for any harmful organisms, thus not carrying any harmful organisms to the patients. 2. You won’t bring the bacterium as what the patient have to your home. 3. It in turn helps you to overcome the same sickness as what the patient has.
4. Hairs should be kept short and clean in order to avoid contamination with you and the patient. While caring the patients there may be a chance of your hair touching the patient and hence you may get the disease causing organism as what the patient has. The patients may also sensitive in receiving organism and other sort of contamination from your hair too.
5. Disinfection is the chemical or the thermal process that is commonly employed in the elimination or killing of the bacterial pathogens except some spores. Disinfection is the one which is less lethal when compared with the sterilization process that is being employed. Disinfectants are...