o It is found in soil, water, skin flora, and most man-made environments throughout the world.
o P. aeruginosa is an opportunistic human pathogen
o P.aeruginosa fluoresce under UV illumination
o One in ten hospital-acquired infections are from Pseudomonas.
o Cystic fibrosis patients are also predisposed to P. aeruginosa infection of the lungs.
o Pseudomonas is also a common cause of postoperative infection in radial keratotomy surgery patients.
o P. aeruginosa produces colonies with a characteristic "grape-like" or "fresh-tortilla" odour on bacteriological media.
o A TSI slant is often used to distinguish non-fermenting Pseudomonas species from enteric pathogens in faecal specimens.
o P. aeruginosa is naturally a multidrug resistant organism (resistant to a large range of antibiotics)
o It should usually be possible to guide treatment according to laboratory sensitivities, rather than choosing an antibiotic empirically.
o If antibiotics are started empirically, then every effort should be made to obtain cultures, and the choice of antibiotic used should be reviewed when the culture results are available.
Antibiotics that have activity against P. aeruginosa may include:
o Transmission occurs primarily by drinking water or eating food that has been contaminated by the feces (waste product) of an infected person, including one with no apparent symptoms.
o If this is not tolerated or does not provide improvement fast enough, intravenous fluids can also be used.
o Antibacterial drugs are beneficial in those with severe disease to shorten its duration and severity.
o Cholera was one of the earliest infections to be studied by epidemiological methods
Signs and symptoms
o These symptoms usually start suddenly, half a day to five days after ingestion of the bacteria.
o The diarrhea is frequently described as "rice water" in nature and may have a fishy odor.
o An untreated person with cholera may produce 10 to 20 litres (3 to 5 US gal) of diarrhea a day with fatal results.
o For every symptomatic person, 3 to 100 people get the infection but remain asymptomatic.
o Cholera has been nicknamed the "blue death" due to a patient's skin turning a bluish-gray hue from extreme loss of fluids.
o When consumed, most bacteria do not survive the acidic conditions of the human stomach.
o The few surviving bacteria conserve their energy and stored nutrients during the passage through the stomach by shutting down much protein production.
o When the surviving bacteria exit the stomach and reach the small intestine, they need to propel themselves through the thick mucus that lines the small intestine to get to the intestinal walls where they can thrive.
o the cork-screw helical fibers they rotate to propel themselves through the mucus of the small intestine.
o On reaching the intestinal wall, V. cholerae start producing the toxic proteins that give the infected person a watery diarrhea.
o The cholera toxin (CTX or CT) is an oligomeric complex made up of six protein subunits: a single copy of the A subunit (part A), and five copies of the B subunit (part B), connected by a disulfide bond
o A rapid dip-stick test is available to determine the presence of V. cholerae.
o In those samples that test positive, further testing should be done to determine antibiotic resistance
o Inepidemic situations, a clinical diagnosis may be made by taking a patient history and doing a brief examination.
o Treatment is usually started without or before confirmation by laboratory analysis.
o Stool and swab samples collected in the acute stage of the disease, before antibiotics have been administered, are the most useful specimens for laboratory diagnosis.
o If an epidemic of cholera is suspected, the most common causative agent is V. cholerae O1.
A number of special media have been employed for the cultivation for cholera vibrios. They are classified as follows:
1. Alkaline peptone water at pH 8.6
2. Monsur's taurocholate tellurite peptone water at pH 9.2
1. Alkaline bile salt agar (BSA): The colonies are very similar to those on nutrient agar.
2. Monsur's gelatin Tauro cholate trypticase tellurite agar (GTTA) medium: Cholera vibrios produce small, translucent colonies with a greyish-black center.
3. TCBS medium: This is the mostly widely used medium; it contains thiosulphate, citrate, bile salts and sucrose. Cholera vibrios produce flat, 2–3-mm-diameter, yellow-nucleated colonies.
Direct microscopy of stool is not recommended, as it is unreliable.
o Although cholera may be life-threatening, prevention of the disease is normally straightforward if proper sanitation practices are followed.
o Sterilization: Proper disposal and treatment of infected fecal waste water produced by cholera victims and all contaminated materials (e.g. clothing, bedding, etc.) are essential.
o Water purification: All water used for drinking, washing, or cooking should be sterilized by either boiling, chlorination, ozone water treatment, ultraviolet light sterilization (e.g. by solar water disinfection), or antimicrobial filtration in any area where cholera may be present.
محتويات مواقع أعضاء هيئة التدريس بما فيها من نصوص وملفات وصور وأبحاث وأية مواد أخرى هي مسئولية عضو هيئة التدريس بالكامل بصفته صاحب الموقع وبما له من صلاحية مطلقة في الإضافة والحذف، وتخلي الجامعة مسئوليتها عن محتويات تلك المواقع.
جميع الحقوق محفوظة © عمادة تقنية المعلومات والتعليم عن بعد 2018م ــ 1440هـ.