Laboratory Manual and Workbook in Microbiology Applications to Patient Care).
It is also called as bacillary dysentery. Universally gastro-enteritis is caused by Shigella. It may cause bloody diarrhea also called dysentery or cause non bloody diarrhea. Shigella gains entry through epithelial lining of large intestine and obliterate the intestinal mucosa. The infection is highly contagious and is responsible for over 600,000 or more deaths per year. Most victims are from developing nations and in areas of overcrowding where poor sanitation persist; jails, mental hospitals, refugee camps, daycare or in primary schools (Scarpignato, C, Lanas A, Bacterial Flora in Digestive Disease: Focus on Rifaximin (Digestion)).
Classical symptoms include watery loose stool, abdominal pain, mild fever, abdominal cramps, painful stools, frequent stools with bloody mucus. Some of the strains of Shigella are known to produce toxin that result in "hemolytic uremic syndrome"( Scarpignato, C, Lanas A, Bacterial Flora in Digestive Disease: Focus on Rifaximin (Digestion)).
Clinical Sample: Stool/ feces/ blood/ rectal swab (Josephine A. Laboratory Manual and Workbook in Microbiology Applications to Patient Care)Positive cultures are obtained from blood-tinged plugs of mucus of freshly passed stools. Rectal swabs are collected if arrangements are there for rapid processing of the sample or holding solution containing: buffered glycerol saline is available (Scarpignato, C, Bacterial Flora in Digestive Disease: Focus on Rifaximin (Digestion)).
Microscopic Examination: Bacillary dysentery characterized by sheets of PMN
Morphology & Staining: Differential Gram staining is performed show gram negative bacilli.
Processing of the clinical sample is done with the following protocol to confirm causative agent.
(Josephine A. Laboratory Manual and Workbook in Microbiology Applications to Patient Care)
Media: Low selectivity: MacConkey, EMB
Intermediate Selectivity: Xylose Lysine Desoxycholate, Desoxycholate Citrate Agar, Salmonella Shigella agar and Hektoen enteric agar (HE)
Highly selective: Bismuth sulphite (BS) agar and brilliant green agar (BG).
Serological Tests of Salmonellosis: Widal test (H and O agglutination for typhoid and paratyphoid patients), CIEP, Haemagglutination, ELISA, Bactericidal Antibody test, Adherence test for detection of IgM antibodies, RIA, Co-agglutination test, Latex agglutination test, PCR, Diazo test of Urine, bacteriophage typing (Josephine A. Laboratory Manual and Workbook in Microbiology Applications to Patient Care).
For detection of Salmonella, 8 hour of pre-enrichment is performed, persuaded by automated DNA extraction and a sensitive real-time PCR. Optimization of this method is done to obtain highest possible yield of cells and DNA to ensuring public health (Josefsen, M. H., Appl. Environ. Microbiol. 2007).
Serological Tests of Shigellosis: Slide agglutination with antisera for serogroup and serotype, PCR, ELISA, Monoclonal Antibodies test.
Biochemical reactions: MR +, reduce nitrate to nitrite, citrate utilization-ve, inhibited by KCN, H2S-ve,catalase+ve, oxidase+ve,