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In a home for mentally handicapped children indole positive variants of Shigella boydii 1 were isolated beside indole negative strains of the same serotype. The variants differed from the indole negative counterparts in fermenting dulcitol, raffinose, and in the absence of splitting trehalose. In antigenic structure the indole positive variant was identical with the type strain. The isolates gave positive guinea pig eye test.
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This study investigated Shigella species' antibiotic resistance patterns and genomic characteristics from small ruminants and manure collected in Potchefstroom, North West, South Africa. Whole genome sequencing was used to determine resistome profiles of Shigella flexneri isolates from small ruminants' manure and Shigella boydii from sheep faeces. Comparative genomics was employed on the South African 261 S. flexneri strains available from GenBank, including the sequenced strains in this study, by investigating the serovars, antibiotic resistance genes (ARGs), and plasmid replicon types. The S. flexneri strains could not be assigned to known sequence types, suggesting novel or uncharacterized lineages. S. boydii R7-1A was assigned to sequence type 202 (ST202). Serovar 2A was the most common among South African S. flexneri strains, found in 96% of the 250 compared human-derived isolates. The shared mdf(A) was the most prevalent gene, identified in 99% of 261 S. flexneri genomes, including plasmid replicon types ColRNAI_1 (99%) and IncFII_1 (98%). Both species share a core set of resistance determinants mainly involving β-lactams (ampC1, ampC, ampH), macrolides (mphB), polymyxins (eptA, pmrF), multidrug efflux pumps (AcrAB-TolC, Mdt, Emr, Kpn families), and regulatory systems (marA, hns, crp, baeRS, evgAS, cpxA, gadX). However, S. boydii possesses additional resistance genes conferring resistance to tetracyclines (tet(A)), phenicols (floR), sulphonamides (sul2), and aminoglycosides (APH(3'')-Ib, APH(6)-Id), along with the acrEF efflux pump components (acrE, acrF). In contrast, S. flexneri harboured unique genes linked to polymyxin resistance (ugd) and regulatory functions (sdiA, gadW) that were absent in S. boydii. These findings highlight Shigella strains' genomic diversity and antimicrobial resistance potential in livestock-associated environments. Moreover, S. boydii highlights the potential risk of multidrug-resistant bacteria in farming and environmental routes. KEY POINTS: • First whole genome study of Shigella from manure and small ruminants in South Africa. • Shigella boydii strain carried multiple resistance genes to β-lactams and tetracycline. • Multidrug efflux pump gene mdf(A) was detected in 99% of South African Shigella flexneri strains.
In early January, 1976, an outbreak of gastroenteritis caused by contamination of the water supply system occurred in Salt, Jordan. This outbreak was followed by the appearance of peripheral neuropathy in 19 cases diagnosed as Guillain-Barré Syndrome. Clinically, gastroenteritis was suggestive of Shigellosis and one of nine patients with Guillain-Barré Syndrome, grew Shigella boydii. Epidemiology of the 19 cases with peripheral neuropathy is detailed. Seventeen patients had definite gastroenteritis symptoms prior to their neuropathy. The median incubation period was seven days.
The in-vitro effect of EDTA-Tris-lysozyme solution on 16 pathogenic bacteria of medical or veterinary importance was determined. Marked decreases in bacterial count occurred with Pseudomonas aeruginosa, Escherichia coli, Moraxella osloensis and Campylobacter fetus, and smaller decreses with Salmonella typhimurium, Shigella boydii, Aeromonas hydrophila, proteus mirabilis, Listeria monocytogenes and Erysipelothrix insidiosa. The test solution had no effect on Klebsiella ozaenae, Brucella canis, Cornynebacterium pyogenes, Coryne, renale, Streptococcus equi and staphylococcus aureus.
Certain polysaccharides have been shown to inhibit the antibody response of rabbits to the common enterobacterial antigen (CA). The present investigation revealed that striking differences exist in the immunosuppressive effects of enteric bacteria and their lipolysaccharides (lps), depending upon CA production by the strains. Mixtures of immunogenic strains (Escherichia coli F2378 [R4], E. coli F470 [R1], or Shigella boydii F3140 [R]) and non-immunogenic CA-producing strains, such as E. coli O1, E. coli O113, Salmonella montevideo, and S. minnesota, as well as the R mutants E. coli F614 (R1), E. coli F757 (R1), and S. typhimurium his 642 (Ra), failed to elicit CA antibodies. In contrast, mixtures of the immunogen and CA-negative strains S. typhimurium his 386 (Ra) and S. minnesota P595 (Re) or R555 (Ra) yielded antibodies in titers similar to those elicited by the immunogen alone. Further, LPS of CA-positive but not of CA-negative strains exerted this immunosuppressive effect. Quantitative studies revealed that LPS of S. minnesota in amounts of 100 mug/ml was strongly immunosuppressive, in amounts of 20 mug/ml slightly effective, and in amounts of 4 mug/ml ineffective. It is postulated that hitherto unknown differences exist, either in composition or in configuration, between LPS obtained from different microorganisms to account for the strain-related differences in immunosuppressive effects and, further, that the immunosuppressive LPS interacts with immunogenic CA.
Antimicrobial resistance (AMR) in Shigella is rising globally, complicating shigellosis management. Whole-genome sequence analysis (WGSA) has advanced our understanding of AMR and transmission dynamics, yet contemporary whole-genome sequencing data from Shigella in sub-Saharan Africa remain scarce. In this study, we applied WGSA to 27 Shigella isolates collected from children presenting with diarrhoea at Ndirande Health Centre in Malawi (2022-2023), as part of the Enterics for Global Health Shigella surveillance study. Serotyping, AMR profiling and phylogenetic analysis revealed Shigella sonnei as the dominant serogroup, with distinct genetic clustering relative to global reference strains among S. sonnei, Shigella flexneri and Shigella boydii. We identified 16 AMR genes linked to ten antimicrobial classes with qnrS1 and qnrB19 genes conferring resistance to fluoroquinolone, alongside IncFIB(K) and IncFII plasmid replicon markers. Importantly, no azithromycin resistance determinants were detected both genotypically and phenotypically, providing baseline evidence that warrants continued surveillance of current first-line treatment. However, the detection of fluoroquinolone resistance genes with plasmid replicon markers in the absence of phenotypic resistance might indicate a silent reservoir with epidemic potential. This is the first contemporary Shigella data from a large-scale diarrhoea disease surveillance study in Malawi, providing essential baseline information for guiding antibiotic treatment and future vaccine development efforts, contributing to the efforts to combat shigellosis in Malawi and other similar regions.
Environmental sources of heat-labile enterotoxigenic Escherichia coli are unknown. The feces of 1,086 inhabitants (approximately 5%) of a small town in the Philippines, 28 pigs, and 10 water buffalo were cultured for enteric bacterial pathogens. Twenty-seven persons harbored pathogenic bacteria: five individuals had enterotoxigenic E. coli, 11 Salmonella species, nine Vibrio parahaemolyticus, one Shigella boydii, and one nonagglutinable Vibrio. Enterotoxigenic E. coli were isolated from two of 28 pigs and from one of 10 water buffalo. Cultures of 26 pieces of beef, 25 pieces of pork, and 52 leafy vegetables obtained from a community market failed to grow enterotoxigenic E. coli. None of 47 samples of contaminated surface water contained this pathogen. Serotypes of human and animal strains of enterotoxigenic E. coli were different, although E. coli O78:H12 isolated from a pig has previously been incriminated in human diarrheal disease. In this limited survey of a Philippine community, enterotoxigenic E. coli were isolated from humans and livestock. The possibility that enterotoxigenic E. coli infections are zoonotic warrants further investigation.
In the 10 years 1964-1973, 105,832 isolations of shigellae were reported to the Center for Disease Control through a nationwide surveillance system. The number reported increased by approximately 13% annually, from 5852 in 1964, when only 17 centers reported all 4 quarters; to 16,797 in 1973, when 52 centers reported each quarter. The rate of reported isolations varied from 4.6 per 100,000 persons in 1965 to 9.1 per 100,000 in 1973. Shigella sonnei accounted for 64% of all these isolates and for more than 80% of isolates in 1973. The majority of reported cases of shigellosis occurred in young children and in women of childbearing age. During the 10-year surveillance period, 35 epidemics in 25 states were investigated. Two-thirds of these outbreaks were the result of person-to-person spread; investigations of common-source outbreaks showed the importance of both water and foodstuffs, especially salads, as potential vehicles of contamination. Indian reservations, custodial institutions, and day-care centers were identified as special high-risk settings for the transmission of shigellosis. The emergence of R-factor-mediated antimicrobial-resistance patterns in recent years has necessitated antibiotic sensitivity testing to determine the drug of choice for treatment of individual cases. Initial testing of oral vaccines suggests these vaccines will have only limited usefulness in protecting certain high-risk populations. Public health education coupled with improvements in water and sewerage systems remains the most satisfactory means of control.
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Elective-differentiating solid nutrient media for simultaneous isolation of Vibrioes, Salmonella and Shigella were developed. Antibiotics active against grampostive microflora and dry bile salts inhibiting the growth of Proteus were used as the inhibitors of the growth of the accompanying microflora. The medium was lincomycin and the bile salts may be prepared in a dry form.
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