Shigella Organisms Research Articles

Preventing Foodborne Illness: Shigellosis

Shigella is a Gram-negative, nonmotile, non-sporeforming, rod-shaped bacterium capable of causing disease in humans. Disease occurs when virulent Shigella organisms are consumed and invade the intestinal mucosa, resulting in tissue destruction. Some Shigella strains produce enterotoxin and Shiga-toxin (very much like the verotoxin of E. coli O157:H7). Shigella poisoning, also known as “shigellosis,” is typically self-limiting, treatable, and most people recover quickly. This document is FSHN05-17, one of a series of the Food Science and Human Nutrition Department, UF/IFAS Extension. Originally published September 2005.
 FSHN0517/FS128: Preventing Foodborne Illness: Shigellosis (ufl.edu)

Occurrence of Salmonella and Shigella in edible frogs (<i>Hoplobatrachus spp</i>) from Hanwa Frog market Zaria, Nigeria

Frogs have been associated with bacterial infection among those who handle them resulting in symptoms such as diarrhoea, abdominal cramps, fever and vomiting. Frogs are a rich source of proteins and they are considered a delicacy by some in Nigeria. Considering the high demand for edible frogs, it is important to determine the occurrence of Salmonella and Shigella organisms from edible frogs (Hoplobatrachus spp). Edible frogs (n=202) were collected from February to July, 2016, from the Hanwa frog market, Zaria, Kaduna State. The intestinal contents of each sampled frog were scraped into the selenite broth bottles and cultured on Deoxycholate Citrate Agar for enrichment and isolation respectively. Biochemical test and sugar fermentation tests were carried out on the suspected isolates. Overall, twenty seven 27(13.37%) of the processed samples were suggestive of Shigella, while 22(10.9%) were suspect Salmonella organisms. There was no significant association between sex of the frogs and the isolation of Shigella and Salmonella organisms, despite the high occurrence of Shigella organism (14.17%) in the males. Source wise the occurrence of Salmonella in frogs was high in Tudun Wada (20%), while Katsina (8.5%) had the least. There was also no association between source and Shigella organisms. Frogs within the weight range of 175-224g had the highest occurrence rate for Shigella isolation, while frogs of 73-125g weight range had the highest occurrence rate for Salmonella isolation. This study shows the presence of Shigella and Salmonella organisms in the intestinal contents of frogs. Therefore the unhygienic and unsanitary environment, handling and processing of frogs is of great public health concern and as such measures are to be put together to ensure safety and wholesomeness of the frog meat been sold for human consumption.Keywords: Edible, Frog, Safety, Salmonella , Shigella, Zaria

Detection of Cytosolic Shigella flexneri via a C-Terminal Triple-Arginine Motif of GBP1 Inhibits Actin-Based Motility.

ABSTRACTDynamin-like guanylate binding proteins (GBPs) are gamma interferon (IFN-γ)-inducible host defense proteins that can associate with cytosol-invading bacterial pathogens. Mouse GBPs promote the lytic destruction of targeted bacteria in the host cell cytosol, but the antimicrobial function of human GBPs and the mechanism by which these proteins associate with cytosolic bacteria are poorly understood. Here, we demonstrate that human GBP1 is unique among the seven human GBP paralogs in its ability to associate with at least two cytosolic Gram-negative bacteria, Burkholderia thailandensis and Shigella flexneri. Rough lipopolysaccharide (LPS) mutants of S. flexneri colocalize with GBP1 less frequently than wild-type S. flexneri does, suggesting that host recognition of O antigen promotes GBP1 targeting to Gram-negative bacteria. The targeting of GBP1 to cytosolic bacteria, via a unique triple-arginine motif present in its C terminus, promotes the corecruitment of four additional GBP paralogs (GBP2, GBP3, GBP4, and GBP6). GBP1-decorated Shigella organisms replicate but fail to form actin tails, leading to their intracellular aggregation. Consequentially, the wild type but not the triple-arginine GBP1 mutant restricts S. flexneri cell-to-cell spread. Furthermore, human-adapted S. flexneri, through the action of one its secreted effectors, IpaH9.8, is more resistant to GBP1 targeting than the non-human-adapted bacillus B. thailandensis. These studies reveal that human GBP1 uniquely functions as an intracellular “glue trap,” inhibiting the cytosolic movement of normally actin-propelled Gram-negative bacteria. In response to this powerful human defense program, S. flexneri has evolved an effective counterdefense to restrict GBP1 recruitment.

Clinical Pharmacology of Ampicillin in Neonates and Infants: Effects and Pharmacokinetics

Ampicillin is a bactericidal antibiotic, it penetrates into the bacterial wall better than penicillin G and is active against gram-negative bacteria that are resistant to penicillin G. Ampicillin has a broad-spectrum antimicrobial activity and is the most widely used antibiotic for treating infections caused by Listeria, β-lactamase-negative Haemophilus, enterococci, Shigella, streptococci, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Neisseria gonorrhea, Neisseria meningitis and many coliform organisms. Ampicillin is excreted unchanged in the urine. In neonates with a gestational and postnatal ages of ≤ 34 weeks and ≤ 7 days, respectively, the half-life, the clearance and the distribution volume of ampicillin are 5.0 hours, 0.055 l/h/kg, and 0.40 l/kg, respectively. The ampicillin half-life decreases and the clearance of ampicillin increases with the neonatal maturation whereas the distribution volume is not affected by the neonatal maturation. Ampicillin may be administered orally. Ampicillin penetrates into the cerebrospinal fluid, especially when the meninges are inflamed. The recommended dose of ampicillin is 50 mg/kg every 12 hours in the first week of life, every 8 hours in neonates 1-3 weeks old, and every 6 hours in neonates 4 or more weeks old. Bacteremia, caused by group B Streptococcus, is treated with 150 to 200 mg/kg/day ampicillin and meningitis is treated with 300 to 400 mg/kg/day ampicillin in divided doses. Some organisms are resistant to ampicillin and a combination of gentamicin and a third-generation cephalosporin is recommended. The aim of this study is to review the effects and pharmacokinetics of ampicillin in neonates and infants.

Microbiological assessment of well water at different durations of storage.

Water is the most universally used single necessity of life. To attain a safe water quality to various communities, an understanding of water microbiology and chemistry is therefore imperative. In this study, well water at different storage durations of 0, 2, 4, 6 and 8 weeks were assessed for bacteriological quality using standard microbiological techniques. Black barrel-shaped plastic containers (300 liter capacity) were used for different storage durations. Water samples at the different storage durations were collected from each corresponding containers. Sterile swabs were used to sample the sides and bottom of the storage containers to determine the prevalence of specific bacteria present in the samples. The results obtained showed that 0 week storage had the highest (100.00 CFU mL(-1)) coliform counts while the lowest (28 CFU mL(-1)) was obtained for 8 weeks of storage. Escherichia coli were not found in 4, 6 and 8 weeks old water. 0 and 2 weeks old water contained E. coli and the mean values were 1.80 x 10(4) +/- 0.03 and 1.43 x 10(4) +/- 0.01 CFU mL(-1), respectively (p < 0.05). Salmonella organisms were found in the 0 week old water but absent in the 2, 4, 6 and 8 weeks old water. Shigella count (62.33 x 10(2) +/- 45.30 CFU mL(-1)) was highest in 4 week old water while the lowest (11.0 x 10(3) +/- 1.00 CFU mL(-1)) was found in 6 week old water (p < 0.05). Zero week old water had the lowest significant (p < 0.05) value of 0.35 x 10(4) +/- 0.05 CFU mL(-1) for mesophilic bacteria and the highest value of 50.00 x 10(4) +/- 10.0 CFU mL(-1) was recorded in the 8 weeks old water. Sides and bottom samples were contaminated with coliforms, E. coli, Salmonella and Shigella organisms. It was concluded that the variously stored well water samples were contaminated with bacteria and the values obtained were above the recommended standards by the World Health Organization (WHO).

Acute non-inflammatory epithelial death plays a role in intrinsic defense against enteric bacteria (P3064)

Abstract Host cell death is critical to the fate of bacterial infection, to host innate immune responses, and to disease outcome. In this study we found that Shigella organisms could invade the terminal ileum of the small intestine in mice by 1 hour of early phase infection and be rapidly cleared within 24 hours even though Shigellae are considered human-specific pathogens. Early phase events after oral infection showed epithelial shedding, degranulation of Paneth cells, and cell death in the intestine without any signs of inflammation. Dead products including DNA and intracellular organelles trapped Shigellae and damaged tissue rapidly recovered within a day. These acute responses occurred with both human-specific pathogens such as Escherichia coli and with such murine pathogens as Salmonella typhimurium. Of interest, human intestine also shared this intrinsic defense. Here we propose a general intrinsic mechanism that repels the initial introduction of entero-pathogenic bacteria by sacrificing host cells.

Preventing Foodborne Illness: Shigellosis

Shigellosis occurs when virulent Shigella organisms are consumed and invade the intestinal mucosa, resulting in tissue destruction. Most Shigella infections are spread by stools or soiled fingers of an infected person to the mouth of another person when basic hygiene and handwashing are not properly done. This revised 5-page fact sheet was written by Keith R. Schneider, Soohyoun Ahn, and Renée M. Goodrich-Schneider, and published by the UF Department of Food Science and Human Nutrition, July 2012. FSHN0517/FS128: Preventing Foodborne Illness: Shigellosis (ufl.edu)

Novel genomic tools for specific and real-time detection of biothreat and frequently encountered foodborne pathogens.

The bacterial genera Escherichia, Salmonella, Shigella, Vibrio, Yersinia, and Francisella include important food safety and biothreat agents. By extensive mining of the whole genome and protein databases of diverse, closely and distantly related bacterial species and strains, we have identified novel genome regions, which we utilized to develop a rapid detection platform for these pathogens. The specific genomic targets we have identified to design the primers in Francisella tularensis subsp. tularensis, F. tularensis subsp. novicida, Shigella dysenteriae, Salmonella enterica serovar Typhimurium, Vibrio cholerae, Yersinia pestis, and Yersinia pseudotuberculosis contained either known genes or putative proteins. Primer sets were designed from the target regions for use in real-time PCR assays to detect specific biothreat pathogens at species or strain levels. The primer sets were first tested by in silico PCR against whole-genome sequences of different species, subspecies, or strains and then by in vitro PCR against genomic DNA preparations from 23 strains representing six biothreat agents (Escherichia coli O157:H7 strain EDL 933, Shigella dysenteriae, S. enterica serovar Typhi, F. tularensis subsp. tularensis, V. cholerae, and Y. pestis) and six foodborne pathogens (Salmonella Typhimurium, Salmonella Saintpaul, Shigella sonnei, F. tularensis subsp. novicida, Vibrio parahaemolyticus, and Y. pseudotuberculosis). Each pathogen was specifically identifiable at the genus and species levels. Sensitivity assays performed with purified DNA showed the lowest detection limit of 128 fg of DNA/μl for F. tularensis subsp. tularensis. A preliminary test to detect Shigella organisms in a milk matrix also enabled the detection of 6 to 60 CFU/ml. These new tools could ultimately be used to develop platforms to simultaneously detect these pathogens.

A icsA-targeted PCR for rapid identification of Shigella spp.

Introduction: The genus Shigella contains four species (serogroups): S. dysenteria (serogroup A), S. flexneri (serogroup B), S. boydii (serogroup C), and S. sonnei (serogroup D). Shigella are highly infectious and a dose of 10–100 cells can cause infection. Virulent Shigella organisms cause the human illness known as bacillary dysentery. Bacillary dysentery (shigellosis) causes mild diarrhea, fever, abdominal cramps, and severe fluid loss. Shigella colonize and invade mucosal epithelial cells. Shigella produce icsA(intracellular spread)/VirG protein,a 116-kD surface-exposed outer membrane protein, which mediates actin polymerization to aid in bacterial movement inside the cell. The icsA protein is encoded by the virulence plasmid. IcsA consists of three major domains: an N-terminal signal sequence (amino acids [aa] 1 to 52), to direct Sec dependent protein transport across the inner-membrane; and a C-terminal translocation domain (aa 759 to 1102) that enables export of the remaining N-terminal region of icsA, the passenger domain (aa 53 to 758), across the OM. The purpose of this study was to develop speciesspecific PCR primers for detection of Shigella spp. Methods: A primer was designed for α-domain of icsA gene for the detection of Shigella. The icsA gene was amplified by using PCR and confirmed by sequencing. Results: Specificity data showed that PCR primers produce amplicons from all the Shigella spp., but not from the other species tested. These results suggested that these two PCR primers are quite sensitive in the detection of Shigella spp. in molecular epidemiological studies of shigellosis. Conclusion: This research proved that icsA gene specialized in Shigella spp. therefore icsA could be used for the detection of Shigella in clinical samples.

Convalescent Cultures for Control of Shigellosis Outbreaks

A shigellosis outbreak in the St Louis, Missouri metropolitan area. To evaluate the utility of a second convalescent stool culture following an initial negative convalescent stool culture among persons excluded from work or childcare for shigellosis. An observational study of 219 shigellosis cases. Laboratory-confirmed shigellosis patients who are required to submit 2 negative convalescent stool cultures before returning to childcare facilities or work and who submitted at least 1 culture were included in the study. Univariate and multivariable logistic regression analyses were performed to evaluate potential risk factors for a convalescent stool culture being positive. Of 308 persons, 219 (71%) submitted at least 1 convalescent stool culture, and 164 (53%) submitted 2 negative convalescent stool cultures. Among 172 cases with > or =2 follow-up cultures, the probability that the second test result would agree with the first test result was 7% for a "positive" initial stool culture, and 100% for a "negative" stool culture. When adjusted for age, sex, and child care attendance, treated case-patients who had Shigella organisms in the first convalescent culture were more likely to have had stool collected <48 hours after the treatment completion and were more likely to have been treated with trimethoprim-sulfamethoxazole. Compliance is poor with statutes requiring serial negative stool cultures among certain populations with shigellosis. Absence of Shigella species in the first convalescent stool culture of patients recovering from shigellosis appears to be an adequate measure of bacteriologic cure; however, the health impacts of requiring any convalescent cultures during shigellosis outbreaks remain unclear.

Prevalence of &lt;i&gt;Shigella&lt;/i&gt; Serogroups and Their Antimicrobial Resistance Patterns in Southern Trinidad

The serogroup distribution and antimicrobial susceptibility patterns of Shigella isolates obtained from stool specimens of persons with acute diarrhoea in community-based studies from southern Trinidad during 1997-2006 were reviewed. Of the 5,187 stool specimens, 392 (8%) were positive for Shigella organisms. From these 392 isolates, 88.8% were recovered from children aged >0-10 year(s). Shigella sonnei was the most frequently-isolated serogroup (75%), followed by S. flexneri (19%), S. boydii (4.1%), and S. dysenteriae (1.8%). S. flexneri was the major isolate among the >20-30 years age-group. The most common drug resistance among all age-groups was to ampicillin. All strains of S. flexneri, S. boydii, and S. dysenteriae were fully susceptible to aztreonam, gentamicin, and ciprofloxacin. S. sonnei, the most common species isolated, showed resistance to all antibiotics tested. The data showed that, throughout the study period, the resistance to commonly-used drugs was relatively low. Since resistance to several drugs seems to be emerging, continuous monitoring of resistance patterns is mandatory for the appropriate selection of empiric antimicrobial drugs in the therapy of suspected cases of shigellosis.

Structural and Functional Studies Indicate That Shigella VirA Is Not a Protease and Does Not Directly Destabilize Microtubules

VirA, an essential virulence factor in Shigella disease pathogenesis, is involved in the uptake, motility, and cell-to-cell spread of Shigella organisms within the human host. These functions have been attributed to a VirA protease activity and a mechanism of microtubule destruction via tubulin degradation [Yoshida, S., et al. (2006) Science 314, 985-989]. We report functional and crystallographic data indicating a novel VirA structure that lacks these activities but highlights the homology to the EspG virulence factor of pathogenic Escherichia coli.

Liquid Chromatography/Mass Spectrometry Characterization of Escherichia coli and Shigella Species

Liquid chromatography/quadrupole time of flight mass spectrometry (LC/QTOF MS) utilizing electrospray ionization was employed to monitor protein expression in Escherichia coli and Shigella organisms. Comparison with MALDI/TOF-MS revealed more proteins, particularly above 15 kDa. A combination of automated charge state deconvolution, spectral mirroring, and spectral subtraction was used to reveal subtle differences in the LC/MS data. Reproducible intact protein biomarker candidates were discovered based on their unique mass, retention time, and relative intensity. These marker candidates were implemented to differentiate closely related strain types, (e.g., two distinct isolates of E. coli O157:H7) and to correctly identify unknown pathogens. This LC/MS approach is less labor-intensive than pulsed-field gel electrophoresis, affords greater specificity than real-time PCR, and requires no primers or antibodies. Additionally, this approach would be beneficial during outbreaks of foodborne disease or bioterrorism investigations by complementing methods typically used in diagnostic microbiology laboratories.

Shigellosis: the current status of vaccine development

Shigellosis, a major form of bacillary dysentery, is caused by infection with Shigella organisms. In poor countries, Shigella-caused dysentery is endemic and causes an estimated 163 million illness episodes annually and more than one million deaths. Although several strategies have been used to develop vaccines targeting shigellosis, none has been licensed for use outside China. Owing to the wide range of Shigella serotypes and subtypes, there is a need for a multivalent vaccine representing prevalent species and serotypes. Vaccine development has been limited by the lack of a suitable animal model for vaccine testing. This review discusses the most advanced strategies for Shigella vaccine development including live attenuated, conjugate, broad spectrum, and proteosome-based vaccines and describes current animal models under study. The greatest barrier to the use of vaccine against shigellosis in developing areas is poor immune responses to oral vaccines in children who have minimal maternal antibodies. Clinical studies of promising shigellosis vaccine candidates are urgently needed after confirmation of safety, immunogenicity, and protection in volunteer challenge models.

Prevalence of &lt;i&gt;shigella&lt;/i&gt; serotypes and their antimicrobial sensitivity pattern in asmara, Eritrea,North East of Africa.

The prevalence of Shigella serotypes and their sensitivity pattern was studied from January 2000 to December 2002 for a period of 3 years. Of the 2420 pediatric diarrhoeal stools screened, 84 Shigella organisms were isolated giving an isolation rate of 3.5%. S.flexneri was the predominant serotype (64%) followed by S.dysenteriae type 1(24%). S.boydii was not isolated during the study period. High resistance was observed against ampicillin, chloramphenicol, cotrimaxozole and tetracycline. 6 % isolates of S.flexneri were resistant to Nalidixic acid. The study recorded the prevalence of S.dysenteriae type 1 and S.flexneri in dysentery stools of this geographic area. Keywords : Shigella dysentery, serotypes, antimicrobial resistance. Journal of Biomedical Investigation Vol. 3 (2) 2005: pp. 1-4

Nitrate and bacterial contamination in well waters in Vinh Phuc province, Vietnam

Measurements were made of the nitrate concentration and bacterial contamination of groundwater samples taken from both dug wells and bores in the commune of Hop Thinh', in the administrative district of Vinh Phuc, Vietnam. A significant number (18%) of samples had nitrate concentrations in excess of the WHO Guideline value for drinking water of 50 mg L(-1), with a higher proportion in the dug wells (29%) than the bores (3.8%). High concentrations of thermotolerant coliforms were found in many of the dug wells and even in the deeper drilled bores. At the time of the study no Shigella or other infectious organisms were found. There was no correlation between nitrate concentration and bacterial content and it is concluded that nitrate concentration is not a good indicator for bacterial contamination.

Role of shigella infection in endometriosis: A novel hypothesis

Endometriosis is the presence of endometrial cells and stroma at ectopic sites outside the uterine cavity. The natural history of endometriosis is uncertain, its etiology unknown, the clinical presentation inconsistent, diagnosis difficult and the treatment poorly standardized. It causes significant morbidity due to pelvic pain and infertility among 15-25% of women during their reproductive age. The benign disease causes peritoneal inflammation, fibrosis, adhesions and ovarian cysts but displays features of malignancy, like neo-vascularization, local invasion and distant metastasis. Mechanical, hormonal, immunological, environmental and genetic factors have been implicated in its etiology but provide inconclusive explanations. Present study was carried out on ectopic and eutopic endometriotic tissue specimens collected during laproscopy/laprotomy from cases of endometriosis. mRNA was isolated from the tissues and converted to cDNA by RT and subsequently subjected to differential display Polymerase Chain Reaction using seven sets of arbitrary primers. A unique band was identified only in the ectopic endometriotic tissue, which was sequenced. BLAST search results revealed sequence homology to shigella bacterial DNA leading us to hypothesize that infection may be playing a role in the etiology of endometriosis. This is the first report implicating the role of bacterial infection in the etiology of endometriosis. Shigella is known to invade the mucosa of the colon through the feco-oral route causing Shigellosis. The pathogenesis of shigellosis involves inflammation, ulceration, haemorrhage, tissue destruction and fibrosis of the colonic mucosa resulting in abdominal pain and diarrhoea/dysentery, this is similar to the pathogenesis of endometriosis which also involves inflammation, haemorrhage, tissue destruction and fibrotic adhesions of the pelvic peritoneum resulting in abdominal pain and infertility. The non-motile shigella bacteria invade the deeper mucosal layers by travelling from cell to cell of colonic epithelium, reaching the lamina propria of the colonic mucosa. We propose that, by the same mechanism, the bacteria travel across the colon wall to reach the outer peritoneal surface of the colon, which is in close proximity to the posterior uterine surface in the Pouch of Douglas, the site which incidentally happens to be the commonest site of early endometriosis. Our hypothesis therefore proposes that shigella or shigella-like organisms may be the trigger for the initiation of immunological changes in the pelvic peritoneum causing endometriosis. Once the endometrial cells are implanted at ectopic sites they are sustained by hormones and angiogenic factors. Hence "Infection hypothesis" provides a novel explanation for the etiopathogenesis of endometriosis.

Shigella Species

Shigella Species

Comparison of antimicrobial susceptibility between invasive and non-invasive Shigella organisms

Antimicrobial susceptibility was determined for ten strains of Shigella spp. comparing invasive (invasion plasmid containing) and non-invasive members of each strain. The activity of the antimicrobial agents could be classified into three types from the differences between the minimum inhibitory concentration (MIC) for the invasive and non-invasive shigellae. For type 1, there was no difference between the MIC (an MIC gap) for invasive and non-invasive organisms. For type 2, the MIC for the invasive organisms of a strain was higher than that of non-invasive organisms of the strain. In the third type, macrolides taken in by shigellae through the type III secretion apparatus, more effectively inhibited the growth of invasive than non-invasive organisms.

Human lactoferrin impairs virulence of Shigella flexneri.

Lactoferrin is a glycoprotein present in most human mucosal secretions, including human milk. Lactoferrin is bacteriostatic in low iron media and, in some settings, bactericidal. Lactoferrin impairs ability of Shigella flexneri serotype 5 strain M90T to invade HeLa cells. To determine the mechanism by which lactoferrin decreases invasiveness of Shigella organisms, its effect on the major virulence proteins responsible for bacterial uptake by host cells was evaluated. Lactoferrin induced degradation of invasion plasmid antigens IpaB and, to a lesser extent, IpaC, the key proteins responsible for bacteria-directed phagocytosis by mammalian cells. The lipid A-binding N-terminal portion of lactoferrin (residues 1-33) induces release of invasion antigens but does not induce degradation of IpaBC. Lactoferrin does not directly degrade previously released invasion plasmid antigens but works by making IpaBC susceptible to breakdown by surface-expressed protease(s).