Whole animal dual-RNAseq and testing of bacterial mutants suggest that S. Using a zebrafish ( Danio rerio) model of Shigella infection, we discover that S. The underlying reasons for this dramatic shift are mostly unknown. flexneri, especially in developing countries. However, resistance to quinolones has also been observed since the late 1990s, and some authors have questioned the effectiveness of this class for Shigella ( Datta 2003 Sarkar 20 Pazhani 2004 Talukder 2004).Shigella flexneri is historically regarded as the primary agent of bacillary dysentery, yet the closely-related Shigella sonnei is replacing S. The WHO now recommends that clinically diagnosed cases of Shigella dysentery be treated with ciprofloxacin as first line treatment, and pivmecillinam, ceftriaxone, or azithromycin as second line treatment and lists the others as ineffective ( WHO 2005a). The following antibiotics were used to treat Shigella dysentery:Ĭlass: beta‐lactams: ampicillin, amoxicillin, first and second generation cephalosporins (cefixime, ceftriaxone) and pivmecillinam Ĭlass: quinolones: nalidixic acid, ciprofloxacin, norfloxacin, ofloxacin Ĭlass: macrolides: azithromycin others: sulphonamides, tetracycline, cotrimoxazole, and furazolidone. The choice of antimicrobial drug has changed over the years as resistance to antibiotics has occurred, with different patterns of resistance being reported around the world. The World Health Organization (WHO) recommends that all suspected cases of shigellosis based on clinical features be treated with effective antimicrobials (antibiotics). dysenteriae type 1 is the only Shigella species with chromosomal genes encoding the protein known as Shiga toxin ( Thorpe 2001). dysenteriae type 1 and may be fatal ( Sinha 1987). Haemolytic uraemic syndrome (a complication resulting in kidney failure, bleeding, and anaemia) and leukemoid reaction (blood findings resembling leukaemia) complicate infection due to S. flexneri and who are genetically predisposed can develop Reiter's syndrome (pains in their joints, irritation of the eyes, and painful urination) that can lead to a difficult to treat chronic arthritis ( CDC 2005). Shigellosis may be associated with mild to life‐threatening complications, such as rectal prolapse, arthralgia (painful joints), arthritis, intestinal perforation, and toxic mega colon (extreme inflammation and distension of the colon), central nervous disorders, convulsions, enteropathy (protein‐losing disease of the intestines), electrolyte imbalance of salts, and sepsis ( Sur 20b). Symptoms include fever, diarrhoea and/or dysentery with abdominal cramps and ineffectual and painful straining at stool or in urinating ( Niyogi 2005). The clinical manifestation of shigellosis ranges from an asymptomatic illness to bacteraemia and sepsis. It occurs in densely populated areas and institutions where populations are in close contact with each other, such as day‐care centres, cruise ships, institutions for people with mental or psychological problems, and military barracks ( Shane 2003 Gupta 2004). Shigellosis occurs predominantly in developing countries and is most common where overcrowding and poor sanitation exist. Secondary attack rates, the number of exposed persons developing the disease within one to four days following exposure to the primary case ( Park 2005), can be as high as 40% among household contacts ( Sur 2004). The disease is communicable as long as an infected person excretes the organism in the stool, which can extend up to four weeks from the onset of illness. Only a small number of ingested bacteria are required to produce illness. Shigellae are transmitted by the faeco‐oral route, via direct person‐to‐person contact, and via food, water, and inanimate objects. sonnei was the most frequently detected species in Thailand (85%, von Seidlein 2006), Israel (48.8%, Mates 2000), and the USA (75%, Gupta 2004 Shiferaw 2004). flexneri was reported to be most prevalent in India (58%, Dutta 2002) and Rwanda (68%, Bogaerts 1983), while S. The species distribution varies globally for example, S. sonnei have more than one genetically distinct subtype (serotype) ( von Seidlein 2006). boydii are the four species of small, Gram‐negative, non‐motile bacilli that cause shigellosis, and all but S.
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