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Cholera has been a killer disease in most of the developing countries mainly affecting children under the age of five and the old. Other many cases have associated with the travellers visiting these regions. The microbe responsible for this is called Vibrio cholerae. Those infected pick this microbe from the food or water that they consume. Due to the high rate of diarrhoea and vomiting the cholera toxin causes most victims die of dehydration, it is estimated that 70% of these cases succumb to death if untreated. It is with this respect that most people should be knowledgeable on how to prevent and control the contamination by the microbe. A literature review is aimed at collecting comprehensive information regarding this microbe from the laboratory determination to the epidemiological patterns related to the Vibrio cholerae.
Identification
Testing results for Vibrio cholerae | ||||
Test | Purpose of test | Reagents/media | Observations | Results |
Gram stain
|
Determine if it is gram positive or gram negative | Crystal violet. Gram's iodine. 95% ethanol. Safrinin. |
The resultant colour was pink | Gram negative |
Oxidase test | Check enzyme cytochrome production. | Kovacs reagent Trypticase soy agar |
Purple colonies | Oxidase positive |
Immobilisation test | Prove specimen motility | Liquid specimen | Movement | Presence of Vibrio spp. |
Morphology
|
Detect the shape | Liquid specimen | Curved/ comma shaped | Vibrio spp
|
Na+ test | Determine sodium influence on growth | Tryptic soy agar -yeast extract with NaCl solutions and without. |
Growth optimum with saline solution | Vibrio cholerae present |
The Gram stain test is conducted to differentiate between gram positive and negative bacteria, the positive bacteria show purple colour at the end of the test while the gram-negative give pink colour. The oxidase test in this case is primary in distinguishing between the Enterobactriaceae and the Vibrio spp with prime difference being the absence of enzyme cytochrome in Vibrio cholerae. Test mobilisation is done to show motility and morphology check confirms the features present in Vibrio spp. Growth media is also used to conclude that indeed the specimen is Vibrio cholerae. (Bergey's Manual of Determinative Bacteriology.)
Vibrio cholerae
Description
Vibrio cholerae belongs to the family Vibrionaceae and it is a facultative anaerobe. It is 1.4-2.6µm in length, gram-negative, do not bear or produce spores and it has a curved shape. The microbe also has the ability to carry out both fermentative metabolism and respiratory metabolism. The bacterium is a monoflagellate, the flagella is sheathed and located at the polar end apart from that it can reduce nitrate and it is also oxidase positive.
To initiate its growth in a Petri dish for Vibrio cholerae addition of 1% sodium chloride is necessary. The microbes can survive both in estuarine, marine and fresh water points; however the fresh water points should have minimal sodium chloride levels. The microbe is infamous for causing cholera, which is a major public health concern especially in developing countries. It is highly linked with poverty and low hygiene. The disease has water as its transmission point and once the parasite is passed on the symptoms include prolific passing of watery stool and vomiting. This signs are attributed to the cholera contaminant and the death is due to high dehydration. (Center for Disease Control and Prevention, 1994).
Background
As earlier stated Vibrio cholerae causes cholera, this disease causes an estimate of 120000 deaths per annum in the global level. The traits that it has left behind include rampant infections in children under the age of five years, drug resistance over time, development of new strains as a result of drug abuse and can also be termed as recurring condition. The occurrences for most times occur in highly populated areas with low sanitation conditions.
Transmission; The disease is water borne and since the inhabitants of these areas do not get clean water the risk is usually high.
Symptoms; The common signs of the infection are copious diarrhoea and vomiting. Since these are major signs others include loss of appetite, general malaise and dry skin.
Treatment; After laboratory confirmation of the parasite the patient is put under drip to restore the electrolyte and water lost through diarrhoea and vomiting. Antibiotics are also prescribed to counter the bacterium. Other mineral restoring prescription should be administered to cover for the lost potassium and bicarbonate lost. The acid-base balance should also be checked.
There has been a total of seven major pandemics from this bacterium first one recorded in 1817 in India. The largest of them all was the seventh pandemic which started in Indonesia and spread to all Asia, Middle East, Africa, and South America before finally landing to North America. Deaths were estimated to be more than 400000.
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The first isolation of the bacterium was done by Robert Koch in 1883 in Egypt and 1884 in India he called it 'comma bacilli'. Since the introduction of antibiotics the bacterium showed signs of resistance and since then research has been going on to produce new drugs. Latest results show that the strains are becoming more resistant to ampicillin and neomycin however there is a reverse trend for the case of chloramphenical and streptomycin.
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