[Music] chosis pathogenesis shagel causes invasive diarrhea most common site of infection is colon rectal mucosa chagala inter andas sites most efficiently via the cell's basal lateral surfaces in the colonic mucosa shagel enters both colonic and terites and specialized epithelial cells microfold cells that overly mucosal lymphoid follicles entry via the M cells is thought to be an important route of entry in clinical infection as suggested by examination a rectal biopsies from humans infected with chela in which lesions were frequently located over lymphoid follicles many alterations to host cells that are triggered by chagala infection are specifically induced by chagala fector proteins that are injected into the cytoplasm of host cells by a bacterial secretion system known as type 3 secretion shagel induced micropinocytosis occurs through extensive rearrangements of the host cell cytoskeleton that cause the formation of large extensions of the host cell membrane in which the bacteria become engulfed step one soon after uptake by induced phagocytosis the bacterium Li the fosic vacu releasing it into the host cell cytool step two short filaments of host cell actin Brown thick lines then organize into a tight bundle that forms a tail several microns in length behind the bacterial body step three the bacterium uses this tail to motor both its movement through the cytool and its passage into protrusions from the cell surface surface the bacterium containing protrusions can extend several bacterial lengths away from the cell surface with the bacterium at the tip step four the bacterium containing protrusion tips are endocytose by adjacent cells thereby transferring the bacterium into the adjacent cell step five once endocytose within the adjacent cell the bacterium lies the membranes that surround it freeing itself into the cytool of that cell this mechanism of cellto cell passage enables the bacteria to spread from the host cell to the host cell without being retained within a true macropinocytosis vacu or having contact with the contents of the intestinal Lumen by remaining within the cytoplasm the microorganism evades the toxic consequences of phagolysosomal fusion as well as other elements of the host defense system immunity following natural infection appears to occur as evidence by the observation that disease due to endemic chela species occurs primarily in children while disease due to epidemic species occurs in all age groups clinical manifestations chagala is an infection of the colon particularly the recto sigmoid portion of the colon patients with chagala gastroenteritis typically present with high fever abdominal cramps and bloody mucoid diarrhea the incubation period ranges from 1 to 3 days with an average of 2 days stool frequency is typically 8 to 10 per day but may increase to up to 100 per day significant fluid loss is uncommon average approximately 30 ml per kilogram per day this is in contrast to small bowel infections which are typified by large volumes of watery diarrhea associated with abdominal cramping bloating gas and weight loss shagala sunnii commonly causes mild disease which may be limited to watery diarrhea whereas as Shaga denter I 1 or shagel flexer commonly causes dysenteric symptoms bloody diarrhea intestinal complications several intestinal complications can occur in the setting of chagala infection each is relatively rare proctitis or rectal prolapse in infants and young children the severe inflammation of the rectum in distal colon that is induced by the invasion of the organism into the colonic mucosa may lead to proti or rectal prolapse toxic megacolon toxic megacolon occurs primarily in the setting of disari 1 infection intestinal obstruction severe colonic disease may result in intestinal obstruction colonic perforation colonic perforation is an extremely rare complication of chosis systemic complications chosis may be associated iated with a number of systemic complications bacteremia signs that correlate with bacteria are lucyisanerd C severe dehydration and lethargy bacteria is more common among children than adults occurring primarily among children younger than 5 years of age neurologic disease seizures are the most common neurologic complication associated with chagal infection seizures occur almost exclusively among children younger than 15 years of age a particularly lethal form of chosis is known as the akiri syndrome the akiri syndrome was associated with chela sunnii infection it was characterized by the rapid development of seizures and coma in patients with high fever and few dysenteric symptoms the mechanism of the full minute course remains unclear hemolytic ureic syndrome although relatively uncommon hemolytic ureic syndrome is the most frequent cause of acute renal failure among infants and young children worldwide 90% of cases of hemolytic ureic syndrome in children follow a diarrheal prum it is most often due to infection with Shiga toxin producing aseria coli but may also be induced by infection with chela disi 1 diagnosis shagel should be suspected Ed in the setting of frequent small volume bloody stools abdominal cramps and tenesmus particularly if accompanied by fever nausea and vomiting are notably absent in most patients the presence of white blood cells and red blood cells on Direct microscopic examination of the stool is consistent with the diagnosis of shagel these findings should raise suspicion of the diagnosis prior to the availability of microbiological testing results stool culture stool culture is the preferred method for the diagnosis of shagel as it provides an isolate for subsequent susceptibility testing culture from a stool sample may give a better yield than culture from a rectal swab the best yield is from a mucoid part of the stool if transport of the sample is required the best medium is buffered glycero saline molecular Diagnostics polymerase Chain Reaction has been used to detect specific DNA sequences frequently a group of chagal specific genes known as Invasion plasmid antigen H which enables the detection of as few as 10 to 100 chagala flexer organisms susceptibility testing antimicrobial susceptibility testing should be performed on all shagel isolates to inform antibiotic selection if treatment is indicated treatment adults antimicrobial resistance the increasing antimicrobial resistance of shagel species is a major problem in the treatment of shagel gastroenteritis therefore antibiotic susceptibility testing is essential for the management of all patients with shagel infection supportive therapy hydration is important to compensate for fluid loss from the gastrointestinal tract oral rehydration is sufficient in most cases intestinal antimotility drugs such as paragor Dien oxalate or laramide should be avoided because of concerns about prolongation of fever diarrhea and bacterial shedding antibiotic treatment empiric therapy for symptomatic adult patients with documented Challo infection we suggest antibiotic therapy antibiotics are effective in shortening the duration of fever and diarrhea caused by Challo infection by about 2 days selection of antibiotic therapy for Challo infection in adults should be based on the results of antimicrobial susceptibility testing if possible for patients who have no clear risk factors for drug resistance fluoroquinolone is a reasonable empiric option empiric treatment for individuals at high risk of having a multi-drug resistant isolate can include a third generation seyos sporin until susceptibilities are available directed therapy results of antimicrobial susceptibility testing should guide antibiotic regimen selection treatment options generally include fluoroquinolone aiyin and third generation cephalosporin trimethoprim sulfamethoxazol and ampicillin are also options if susceptibility is documented prevention frequent handwashing with soap and water is important for prevention particularly after using the restroom and prior to food preparation they should also avoid sex until 2 weeks after the resolution of diarrhea and practice safe sex for several additional weeks because of the possibility of asymptomatic bacterial shedding patients who are not treated should continue these precautions for several weeks after diarrheal symptoms have improved treatment children correction of fluid and electrolyte losses is the main stay of treatment for acute gastroenteritis in children avoid antimotility drugs for example paragor Dien oxalate laramide in children with suspected chosis because they may prolong symptoms and excretion of the organism parenteral antimicrobial therapy is recommended for children with proven or suspected chigal losis and one or more of the following severe toxemia or suspected bacteremia underlying immune deficiency and inability to take oral medications sept triaxone and aiyin is the firstline paral therapy for shigal Lois and children younger than 18 years of age if the susceptibility of the isol is unknown oral treatment of chigal Lois depends upon local resistance patterns image based discussion this image of triple sugar iron AER slant shows the reaction pattern of shagel this pattern is designated alkaline red over acid yellow indicating the absence of lactose fermentation by the test organism in addition there's no gas or the black color indicative of hydrogen sulfide visible in this image we can see motility testing on non-lactose fermenting gram negative rods in the left tube the non-modal shagel does not migrate away from the central stab line in the AER in the right tube motal Proteus produces visible opacification of the Ager away from the central stab line the color difference between the two samples is unrelated to the motility test this image shows shagel versus UA's positive G negative rods on Uria slant Uria slant shows the positive pink and negative yellow reactions that differentiate Proteus left from chela right in this image isolates of salmonella and Chella can be presumptively identified by a glutin with appropriate antisera a positive utenation is on the left a negative utenation on the right here is a scanning electron microscopy of hel cells infected by Shela Flex nerri the cytoskeleton has been insolubilized and the host cell membrane has been removed a dividing bacterium is seen with tight bundles of actin filaments at one extremity here's an image of selective media used in the isolation of enic pathogens from the stool on each plate shagel is indicated by the arrowhead and asaria coli by the arrow all three media differentiate lactose fermenting from non-lactose fermenting organisms by pH sensitive dyes image a Maki acre image B hecto anic AER and image C xylos line deoxycholate AER that's all for the video we'll see you next time