Property:Explanation
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''Campylobacter jejuni'' is a curved, helical-shaped, non-spore forming, non-glucose-fermenting, microaerophilic, gram-negative bacteria. It is one of the most common causes of human gastroenteritis worldwide. Infection with ''C. jejuni'' occurs following invasion of the microorganism of the colonic mucosa with disruption of epithelial cells. ''C. jejuni'' has also been associated with subsequent development of Guillain-Barré syndrome, which usually develops two to three weeks after the initial illness. ''C. jejuni'' is commonly associated with ingestion of poultry as it naturally colonizes the digestive tract of many bird species. ''C. jejuni'' is grown on specially selective agar plates at 42°C, the normal avian body temperature, rather than at 37°C, the temperature at which the majority of other pathogenic bacteria are grown. Since the colonies are oxidase positive, they will usually only grow in scanty amounts on the plates. Microaerophilic conditions are required for abundant growth. A selective blood agar medium (Skirrow's medium) may also be used.
The following include the mportant oxidase-positive pathogens:<br>
*''Campylobacter''
*''Helicobacter''
*''Legionella''
*''Neisseria''
*''Pseudomonas''
*''Vibrio''<br/>
'''Educational Objective:''' Campylobacter jejuni grows at 42°C and causes intestinal disease by invasion of the colonic mucosa.<br/>
'''References:''' First Aid 2015 page 138. +
''Escherichia coli'' O157:H7 (EHEC) is an enterohemorrhagic strain of ''Escherichia coli''. Infection may lead to hemorrhagic diarrhea and subsequent development of hemolytic-uremic syndrome (HUS). Transmission is via the fecal-oral route, and the majority of cases are associated with ingestion of undercooked, contaminated ground beef or pork.
''E. coli'' O157:H7 is negative for invasiveness (Sereny test), adheres through the E. coli common pilus (ECP), and does not produce heat-stable or heat-labile toxins. In addition, ''E. coli'' O157:H7 is usually sorbitol negative, whereas other ''E. coli'' ferment sorbitol. ''E. coli'' O157:H7 also lacks the ability to hydrolyze 4-methylumbelliferyl-β-D-glucuronide (MUG) and does not grow at 45 °C in the presence of 0.15% bile salts (cannot be isolated by using standard fecal coliform methods that include incubation at 45 °C).
Among the virulence factors are periplasmic catalase and shiga-like toxins. Shiga-like toxin (SLT-1) is an iron-regulated toxin that catalytically inactivates 60S ribosomal subunits of eukaryotic cells. It cleaves N-glycoside bond of adenine in 28S rRNA of the 60S ribosome unit to prevent EF-1-dependent aminoacyl tRNA binding, thereby inhibiting protein synthesis.<br/>
'''Educational Objective:''' ''Escherichia coli'' O157:H7 (EHEC) is an enterohemorrhagic strain of ''Escherichia coli''. Transmission is via the fecal-oral route, and the majority of cases are associated with ingestion of undercooked, contaminated ground beef or pork. Shiga-like toxin-1 (SLT-1) of EHEC cleaves N-glycoside bond of adenine in 28S rRNA of the 60S ribosome unit to prevent EF-1-dependent aminoacyl tRNA binding, thereby inhibiting protein synthesis.<br/>
'''References:''' First Aid 2015 page 138. +
''E. coli'' O157:H7 (EHEC) is negative for invasiveness (Sereny test), adheres through the ''E. coli'' common pilus (ECP), and does not produce either heat-stable or heat-labile toxins. In addition, ''E. coli'' O157:H7 is usually sorbitol-negative, whereas other ''E. coli'' ferment sorbitol. Among the virulence factors, Shiga-like toxin (SLT-1) is an iron-regulated toxin that catalytically inactivates 60S ribosomal subunits of eukaryotic cells. It cleaves N-glycoside bond of adenine in 28S rRNA of the 60S ribosome unit to prevent EF-1-dependent aminoacyl tRNA binding, thereby inhibiting protein synthesis. This mechanism of action is similar to tetracyclines, which also inhibit protein synthesis by blocking the entry and binding of aminoacyl transfer RNA.<br/>
'''Educational Objective:''' Among the virulence factors of ''E. coli'' O157:H7, Shiga-like toxin (SLTs) is an iron-regulated toxin that catalytically cleaves N-glycoside bond of adenine in 28S rRNA of the 60S ribosome unit to prevent aminoacyl tRNA binding, thereby inhibiting protein synthesis. This mechanism of action is similar to tetracyclines, which also inhibit protein synthesis by blocking the entry and binding of aminoacyl transfer RNA.<br/>
'''References:''' First Aid 2015 page 138. +
Enterotoxigenic ''Escherichia coli'' (ETEC) is a type of ''Escherichia coli'' and the leading bacterial cause of diarrhea in the developing world, as well as the most common cause of travelers' diarrhea. Enterotoxins produced by ETEC include heat-labile enterotoxin (LT) and heat-stable enterotoxin (ST). LT activates adenylyl cyclase and increases the amount of cAMP, and results in profound chloride efflux secondary to phosphorylation of CFTR by persistently activated protein kinase A. ST activates guanylyl cyclase in the signal pathway of the enteric epithelial cells and triggers fluid secretion.<br/>
'''Educational Objective:''' Enterotoxins produced by ETEC include heat-labile enterotoxin (LT) and heat-stable enterotoxin (ST). LT activates adenylyl cyclase and increases the amount of cAMP, and results in profound chloride efflux secondary to phosphorylation of CFTR by persistently activated protein kinase A. ST activates guanylyl cyclase in the signal pathway of the enteric epithelial cells and triggers fluid secretion.<br/>
'''References:''' First Aid 2015 page 138. +
Mild to moderate alcohol withdrawal manifests as autonomic hyperactivity, insomnia, tremulousness, anxiety, sweating, hypertension, tachycardia and fever. Patients with chronic alcohol use can also present with hallucinations. Visual hallucinations are more common, but auditory and tactile hallucination can also be present. Severe alcohol withdrawal manifests with seizures and delirium tremens. Delirium tremens usually occurs after 2-4 days of alcohol abstinence.<br/>
'''Educational Objective:''' <br/>
'''References:''' +