Anthrax is a highly infectious disease that normally affects herbivores (livestock) and unfortunately may also spread to humans through inhalation, ingestion or any sort of skin contact of the bacterium, Bacillus anthracis. Bacillus anthracis (B. anthracis) is a gram positive spore forming bacterium that invades the human body and leads to various symptoms of Anthrax, depending on how virulent it has become. These symptoms include; swollen neck glands, bloody diarrhoea, vomiting blood, extreme tiredness and blisters on the skin that eventually turn black. If Anthrax is suspected, the mode of transmission will determine what tests to do and what sample to use. Non-molecular methods and molecular methods are normally used in clinical laboratories
…show more content…
anthracis from any other closely related Bacilli species (the medium inhibits the growth of any other contaminating agents and Bacilli species, other than B. anthracis). If the patient is suspected of having pulmonary anthrax, then sputum is the most common sample that will be used to test for the organism. Sputum is collected from a non-sterile site, therefore before it is inoculated on the PLET medium, it has to be emulsified with 0.9% sterile saline. The suspension is then heated at 65®C for 15-20 minutes in an incubator, this step is done to destroy any vegetative cells of contaminating organisms. Using a sterile applicator spreader, aliquot 0.25ml of the suspension and spread it on the PLET medium then incubate the medium at 37®C. Inspect for growth on the medium every 8 hours for 48 hours of incubation. If B. anthracis is present then small, white, domed and circular colonies will form, after 24 hours the colonies become rough with a ground-glass texture and a cream to pale teal-blue colour. Various confirmatory tests are done on the single conies formed on the PLET medium; the colonies are inoculated on 5% sheep blood agar and incubated at 37®C for 24 hours. B. anthracis grows on sheep blood agar and appear as grey, non-haemolytic colonies that have a medusa head or comet tail shape. A last confirmatory test that can be done is the
anthracis from any other closely related Bacilli species (the medium inhibits the growth of any other contaminating agents and Bacilli species, other than B. anthracis). If the patient is suspected of having pulmonary anthrax, then sputum is the most common sample that will be used to test for the organism. Sputum is collected from a non-sterile site, therefore before it is inoculated on the PLET medium, it has to be emulsified with 0.9% sterile saline. The suspension is then heated at 65®C for 15-20 minutes in an incubator, this step is done to destroy any vegetative cells of contaminating organisms. Using a sterile applicator spreader, aliquot 0.25ml of the suspension and spread it on the PLET medium then incubate the medium at 37®C. Inspect for growth on the medium every 8 hours for 48 hours of incubation. If B. anthracis is present then small, white, domed and circular colonies will form, after 24 hours the colonies become rough with a ground-glass texture and a cream to pale teal-blue colour. Various confirmatory tests are done on the single conies formed on the PLET medium; the colonies are inoculated on 5% sheep blood agar and incubated at 37®C for 24 hours. B. anthracis grows on sheep blood agar and appear as grey, non-haemolytic colonies that have a medusa head or comet tail shape. A last confirmatory test that can be done is the