Comparative Genomics and Characterization of Shigella flexneri Isolated from Urban Wastewater.

Shigella species are a group of highly transmissible Gram-negative pathogens. Increasing reports of infection with extensively drug-resistant varieties of this stomach bug has convinced the World Health Organization to prioritize Shigella for novel therapeutic interventions. We herein coupled the whole-genome sequencing of a natural isolate of Shigella flexneri with a pangenome ana-lysis to characterize pathogen genomics within this species, which will provide us with an insight into its existing genomic diversity and highlight the root causes behind the emergence of quick vaccine escape variants. The isolated novel strain of S. flexneri contained ~4,500 protein-coding genes, 57 of which imparted resistance to antibiotics. A comparative pan-genomic ana-lysis revealed genomic variability of ~64%, the shared conservation of core genes in central metabolic processes, and the enrichment of unique/accessory genes in virulence and defense mechanisms that contributed to much of the observed antimicrobial resistance (AMR). A pathway ana-lysis of the core genome mapped 22 genes to 2 antimicrobial resistance pathways, with the bulk coding for multidrug efflux pumps and two component regulatory systems that are considered to work synergistically towards the development of resistance phenotypes. The prospective evolvability of Shigella species as witnessed by the marked difference in genomic content, the strain-specific essentiality of unique/accessory genes, and the inclusion of a potent resistance mechanism within the core genome, strengthens the possibility of novel serotypes emerging in the near future and emphasizes the importance of tracking down genomic diversity in drug/vaccine design and AMR governance.

Identification of therapeutic drug target of Shigella Flexneri serotype X through subtractive genomic approach and in-silico screening based on drug repurposing.

Shigellosis, induced by Shigella flexneri, constitutes a significant health burden in developing nations, particularly impacting socioeconomically disadvantaged communities. Designated as the second most prevalent cause of diarrheal illness by the World Health Organization (WHO), it precipitates an estimated 212,000 fatalities annually. Within the spectrum of S. flexneri strains, serotype X is notably pervasive and resilient, yet its comprehensive characterization remains deficient. The present investigation endeavors to discern potential pharmacological targets and repurpose existing drug compounds against S. flexneri serotype X. Employing the framework of subtractive genomics, the study interrogates the reference genome of S. flexneri Serotype X (strain 2,002,017; UP000001884) to delineate its proteome into categories of non-homologous, non-paralogous, essential, virulent, and resistant constituents, thereby facilitating the identification of therapeutic targets. Subsequently, a screening of approximately 9000 compounds from the FDA library against the identified drug target aims to delineate efficacious agents for combating S. flexneri serotype X infections. The application of subtractive genomics methodology yields prognostic insights, unveiling non-paralogous proteins (n = 4122), non-homologues (n = 1803), essential (n = 1246), drug-like (n = 389), resistant (n = 167), alongside 42 virulent proteins within the reference proteome. This iterative process culminates in the identification of Serine O-acetyltransferase as a viable drug target. Subsequent virtual screening endeavors to unearth FDA-approved medicinal compounds capable of inhibiting Serine O-acetyltransferase. Noteworthy candidates such as DB12983, DB15085, DB16098, DB16185, and DB16262 emerge, exhibiting potential for mitigating S. flexneri Serotype X. Despite the auspicious findings, diligent scrutiny is imperative to ascertain the efficacy and safety profile of the proposed drug candidates vis-à-vis S. flexneri.

Antibiotic-Resistance Profiles and Genetic Diversity of Shigella Isolates in China: Implications for Control Strategies.

The urgent need for comprehensive and systematic analyses of Shigella as the key pathogen led us to meticulously explore the epidemiology and molecular attributes of Shigella isolates. Accordingly, we procured 24 isolates (10 from Xinjiang and 14 from Wuhan, China) and performed serotype identification and antimicrobial susceptibility testing. Resistance gene detection and homology analysis by polymerase chain reaction and pulsed-field gel electrophoresis (PFGE), respectively, were performed for genetic diversity analysis. All isolates were identified as Shigella flexneri, with 70% (35.4-91.9%) and 30% (8.1-64.6%) of the Xinjiang isolates and 85.7% (56.2-97.5%) and 14.3% (2/14, 2.5-43.9%) of the Wuhan isolates belonging to serotype 2a and serotype 2b, respectively. All isolates displayed resistance to at least two antibiotics and complete resistance to ampicillin. Multidrug resistance (MDR) was recorded in 70.8% (48.8-86.6%) of isolates, with Xinjiang isolates exhibiting relatively higher resistance to ampicillin-sulbactam, piperacillin, ceftriaxone, and aztreonam. Conversely, Wuhan isolates displayed higher MDR and resistance to tetracycline, ciprofloxacin, levofloxacin, and cefepime relative to Xinjiang isolates. Molecular scrutiny of antibiotic-resistance determinants revealed that blaTEM was the main mechanism of ampicillin resistance, blaCTX-M was the main gene for resistance to third- and fourth-generation cephalosporins, and tetB was the predominant gene associated with tetracycline resistance. Four Xinjiang and seven Wuhan isolates shared T1-clone types (>85%), and two Xinjiang and one Wuhan isolates were derived from the T6 clone with a high similarity of 87%. Six PFGE patterns (T1, T2, T5, T6-3, T8, and T10) of S. flexneri were associated with MDR. Thus, there is a critical need for robust surveillance and control strategies in managing Shigella infections, along with the development of targeted interventions and antimicrobial stewardship programs tailored to the distinct characteristics of Shigella isolates in different regions of China.

Detection of OXA-181 Carbapenemase in Shigella flexneri.

We report the detection of OXA-181 carbapenemase in an azithromycin-resistant Shigella spp. bacteria in an immunocompromised patient. The emergence of OXA-181 in Shigella spp. bacteria raises concerns about the global dissemination of carbapenem resistance in Enterobacterales and its implications for the treatment of infections caused by Shigella bacteria.

Insights into the antibacterial effectiveness of linalool against Shigella flexneri on pork surface: Changes in bacterial growth and pork quality.

Shigella flexneri has the ability to contaminate pork and cause foodborne diseases. This study aimed to examine the effectiveness of linalool (a natural preservative) against S. flexneri and explore its potential application in contaminated pork. The results showed that linalool was capable of damaging the cell membrane and binding to the DNA of S. flexneri, and inhibiting biofilm formation and disrupting mature biofilms. The antibacterial effectiveness of linalool on the surface of pork was further demonstrated by analyzing the physicochemical properties of the pork (i.e., weight loss rate, pH value, color index, and TVB-N value) and its protein profiles. Linalool did not completely kill S. flexneri in pork at minimum bactericidal concentration (MBC) concentration and its antibacterial effect of linalool was stronger during the initial stage of storage. During storage, linalool influenced the abundance of specific proteins in the pork, particularly those involved in pathways related to fat metabolism. These findings offer novel insights into the antibacterial efficacy of linalool and its underlying mechanism in pork.

An in silico hierarchal approach for drug candidate mining and validation of natural product inhibitors against pyrimidine biosynthesis enzyme in the antibiotic-resistant Shigella flexneri.

Shigella flexneri is the main causative agent of the communicable diarrheal disease, shigellosis. It is estimated that about 80-165 million cases and > 1 million deaths occur every year due to this disease. S. flexneri causes dysentery mostly in young children, elderly and immunocompromised patients, all over the globe. Recently, due to the emergence of S. flexneri antibiotic resistance strains, it is a dire need to predict novel therapeutic drug targets in the bacterium and screen natural products against it, which could eliminate the curse of antibiotic resistance. Therefore, in current study, available antibiotic-resistant genomes (n = 179) of S. flexneri were downloaded from PATRIC database and a pan-genome and resistome analysis was conducted. Around 5059 genes made up the accessory, 2469 genes made up the core, and 1558 genes made up the unique genome fraction, with 44, 34, and 13 antibiotic-resistant genes in each fraction, respectively. Core genome fraction (27% of the pan-genome), which was common to all strains, was used for subtractive genomics and resulted in 384 non-homologous, and 85 druggable targets. Dihydroorotase was chosen for further analysis and docked with natural product libraries (Ayurvedic and Streptomycin compounds), while the control was orotic acid or vitamin B13 (which is a natural binder of this protein). Dynamics simulation of 50 ns was carried out to validate findings for top-scored inhibitors. The current study proposed dihydroorotase as a significant drug target in S. flexneri and 4-tritriacontanone & patupilone compounds as potent drugs against shigellosis. Further experiments are required to ascertain validity of our findings.

The evolutionary history of Shigella flexneri serotype 6 in Asia.

Shigella flexneri serotype 6 is an understudied cause of diarrhoeal diseases in developing countries, and has been proposed as one of the major targets for vaccine development against shigellosis. Despite being named as S. flexneri, Shigella flexneri serotype 6 is phylogenetically distinct from other S. flexneri serotypes and more closely related to S. boydii. This unique phylogenetic relationship and its low sampling frequency have hampered genomic research on this pathogen. Herein, by utilizing whole genome sequencing (WGS) and analyses of Shigella flexneri serotype 6 collected from epidemiological studies (1987-2013) in four Asian countries, we revealed its population structure and evolutionary history in the region. Phylogenetic analyses supported the delineation of Asian Shigella flexneri serotype 6 into two phylogenetic groups (PG-1 and -2). Notably, temporal phylogenetic approaches showed that extant Asian S. flexneri serotype 6 could be traced back to an inferred common ancestor arising in the 18th century. The dominant lineage PG-1 likely emerged in the 1970s, which coincided with the times to most recent common ancestors (tMRCAs) inferred from other major Southeast Asian S. flexneri serotypes. Similar to other S. flexneri serotypes in the same period in Asia, genomic analyses showed that resistance to first-generation antimicrobials was widespread, while resistance to more recent first-line antimicrobials was rare. These data also showed a number of gene inactivation and gene loss events, particularly on genes related to metabolism and synthesis of cellular appendages, emphasizing the continuing role of reductive evolution in the adaptation of the pathogen to an intracellular lifestyle. Together, our findings reveal insights into the genomic evolution of the understudied Shigella flexneri serotype 6, providing a new piece in the puzzle of Shigella epidemiology and evolution.

Novel amylomacins from seaweed-associated Bacillus amyloliquefaciens as prospective antimicrobial leads attenuating resistant bacteria.

The rise in antibiotic-resistant bacterial strains prompting nosocomial infections drives the search for new bioactive substances of promising antibacterial properties. The surfaces of seaweeds are rich in heterotrophic bacteria with prospective antimicrobial substances. This study aimed to isolate antibacterial leads from a seaweed-associated bacterium. Heterotrophic Bacillus amyloliquefaciens MTCC 12716 associated with the seaweed Hypnea valentiae, was isolated and screened for antimicrobial properties against drug-resistant pathogens. The bacterial crude extract was purified and three novel amicoumacin-class of isocoumarin analogues, 11'-butyl acetate amicoumacin C (amylomacin A), 4'-hydroxy-11'-methoxyethyl carboxylate amicoumacin C (amylomacin B) and 11'-butyl amicoumacin C (amylomacin C) were isolated to homogeneity. The studied amylomacins possessed potential activities against Pseudomonas aeruginosa, vancomycin-resistant Enterococcus faecalis, Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus, and Shigella flexneri with a range of minimum inhibitory concentration values from 0.78 to 3.12 µg/mL, although standard antibiotics ampicillin and chloramphenicol were active at 6.25-25 µg/mL. Noticeably, the amylomacin compound encompassing 4'-hydroxy-11'-methoxyethyl carboxylate amicoumacin C functionality (amylomacin B), displayed considerably greater antagonistic activities against methicillin-resistant S. aureus, vancomycin-resistant E. faecalis, Vibrio parahaemolyticus, Escherichia coli, and K. pneumoniae (minimum inhibitory concentration 0.78 µg/mL) compared to the positive controls and other amylomacin analogues. Antimicrobial properties of the amylomacins, coupled with the presence of polyketide synthase-I/non-ribosomal peptide synthetase hybrid gene attributed the bacterium as a promising source of antimicrobial compounds with pharmaceutical and biotechnological applications.

Antibacterial, antifungal and enzymatic activities of azithromycin-heavy metal complexes: Newly synthesized and characterized.

As part of our continuous research to understand the interaction mechanism of drug and metallo-elements, heavy metal complexes of azithromycin (AZI) were synthesized with arsenic oxide, lead carbonate and silver chloride salts in molar ratio of 2: 1 (L: M). Synthesized heavy metal complexes have shown good percent yield and characterized through spectroscopic parameters including UV-Visible, TLC, FT-IR, NMR and elemental analysis (CHN). Spectroscopic characterization reveals the binding of ligand AZI with heavy metals in bi-dentate manner involving the hydroxide and 9a-NCH3 group of the aglycone ring of AZI. These newly synthesized heavy metal complexes were evaluated for their antimicrobial response against selected gram positive and gram negative organisms and antifungal species. It was noted that all newly synthesized complexes exhibits increased activity against B.subtilus whereas, AZI itself didn't show any activity, while synthesized complexes have low to moderate response against all the studied organisms. Complex A-M12 possess greater enzymatic response against both urease and alpha chymotrypsin among all the studied complexes. Results obtained were then statistically analyzed through one way ANOVA and Dunnett's test by using SPSS version 20.0 suggesting the significant response of complexes against selected organisms.

Multi-step Synthesis, Characterization and Photophysical Investigation of Novel Biologically Active Heterocyclic Chalcone (AECO).

Novel alkylated heterocyclic chalcone (E)-1-(2-(allyloxy)phenyl)-3-(9-ethyl-9H-carbazol-3-yl)prop-2-en-1-one (AECO) with extended π-bond was prepared by the multi-steps synthesis. The structure of the AECO was established by the spectroscopic technics and purity of the compound was confirmed by the elemental analysis. Physicochemical parameters of the AECO such as molar absorption coefficient, transition dipole moments, stokes shift, oscillator strength and fluorescence quantum yield were calculated in ten various solvents on the basis of polarity of the solvents to see the effect of the solvent with AECO. Interaction of the AECO chromophore with cationic CTAB and anionic SDS surfactants were determined by using the fluorescence spectroscopy techniques. The intensity of the florescence spectrum increase with increasing the concentrations of surfactants. This suggests that strong interaction occurs between AECO with surfactants and this interaction arise from electrostatic forces. So, AECO chromophore could be used as analysis to define the Critical Micelle Concentration (CMC) of the surfactants. In addition the in-vitro antibacterial active of novel heterocyclic chalcone agents four bacteria's strain were evaluated and result showed AECO is beater antibacterial agent against Gram-Negative Bacteria (E. coli and S. flexneri) as compare to the Gram Negative Bacteria with respected to the standard drug Tetracycline.

Effects of three essential oils and their nano-emulsions on Listeria monocytogenes and Shigella flexneri in Egyptian Talaga cheese.

Talaga cheese is a soft Egyptian cheese that has been associated with foodborne pathogens such as Listeria monocytogenes and Shigella flexneri. Essential oils (EOs) play a pivotal role in sustainably controlling foodborne diseases and as a potential preservative in soft cheeses. However, limited data is available comparing the antibacterial activity of EOs and their nano-emulsions (NEs) when inoculated into Talaga cheese. Therefore, this study aimed to examine the antibacterial activity of carvacrol, clove, and cumin EOs, in addition to their NEs, against L. monocytogenes (NCTC 13372/ATCC® 7644) and S. flexneri (ATCC®12022TW⁎) inoculated into laboratory-manufactured Egyptian Talaga cheese during refrigerated storage. The NEs had a Z-average diameter of 32.98 ± 29.75 nm, 45.2 ± 34.25 nm, and 50.23 ± 15.7 nm and a PDI of 0.326, 0.245, and 0.307 for carvacrol, clove, and cumin NEs, respectively. The flow of active functional groups of EOs and NEs as clarified by Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) showed the spherical-shaped droplet structure of the prepared NEs. The minimum inhibitory concentration (MIC) of all EOs and their NEs was 0.78% against L. monocytogenes and 1.56% against S. flexneri, while those of carvacrol EO and its NE were 0.78% against both microorganisms. By supplementation in cheese, NEs significantly reduced the counts of inoculated pathogens from 8.2 log10cfu/g to 1.5 log10cfu/g after 2 to 3 weeks compared to EOs, which reduced them after 4 to 5 weeks. The carvacrol NE showed excellent antibacterial activity with no cheese sensory impairment. It reduced L. monocytogenes by 99% (R%) after 7 days and after 3 weeks for S. flexneri at 0.78% concentration, while higher concentrations and a longer period were required for the other NEs to show an inhibitory effect. NEs showed a greater antimicrobial effect than their non-emulsified counterparts, especially when interacting with food items, and carvacrol NE at a low concentration (0.78%) demonstrated its efficacy as an antibacterial and natural food preservative.

Antibacterial and antishigellosis activity of Xylopia staudtii (engl. & diels), Annonaceae.

ETHNOPHARMACOLOGICAL RELEVANCE: Xylopia staudtii is a medicinal plant which fruits are traditionally used in western Cameroon as a spice in the preparation of soups known for their abdominal cramp relieving properties. Often identified as Xylopia africana, its bark is used in the treatment of dysentery in Mont Cameroun localities. This plant could therefore contain active ingredients against intestinal pathogens, including Shigella spp, which are responsible of the deathly dysenteric diarrhoea. AIM OF THE STUDY: This study aims to assess the efficacy of the hydroethanolic extract from Xylopia staudtii bark in immunodepressed mice infected with Shigella flexneri. MATERIALS AND METHODS: Qualitative detection of compounds in the crude extract was done using UPLC-DAD-(HR) ESI-MS analysis in an attempt to link the activity to the chemical composition. The MIC and the MBC of the extract was determined using broth dilution method. Shigellosis was induced by intraperitoneal administration of Shigella flexneri to immunodepressed mice pretreated with streptomycin. These infected mice were then treated with the extract (100, 200 and 400 mg/kg), and reference substances (ciprofloxacin and saline). During the 9 days of treatment, animal morphology, fecal pathology and deaths were recorded. At the end of the treatment period, blood and organs were collected from any surviving animals for hematological, biochemical and histopathological analyses. RESULTS: The extract was found to be significantly active, with a bactericidal effect against Shigella and a bacteriostatic effect against Escherichia coli. It was able to reduce and stop the faecal pathology caused by the infection in mice, as well as the rate of deaths which was brought to zero (0) in animal treated at 400 mg/kg. The bacteria load in faeces was reduced by 100% in animal treated at 400 mg/kg. Xylopia staudtii extract elicited anti-inflammatory properties by reducing MPO activity and Lcn2 intestinal level. It also prevents damages in the intestinal tissue and the shortening of colon which characterise Shigella infection. The serum level of ASAT, ALAT, bilirubin, urea and creatinine in animals treated with the extract was similar to those of normal animal used in the study. These activities of the plant may be due at least in part to the presence of ent-kauran type diterpens such as kaurenoic acid identified in the extract. CONCLUSION: These findings support the usage of Xylopia staudtii as an antimicrobial against bacillary dysentery, making this plant a potential candidate for the formulation of an improved standardized traditional medicine.

Evolutionary histories and antimicrobial resistance in Shigella flexneri and Shigella sonnei in Southeast Asia.

Conventional disease surveillance for shigellosis in developing country settings relies on serotyping and low-resolution molecular typing, which fails to contextualise the evolutionary history of the genus. Here, we interrogated a collection of 1,804 Shigella whole genome sequences from organisms isolated in four continental Southeast Asian countries (Thailand, Vietnam, Laos, and Cambodia) over three decades to characterise the evolution of both S. flexneri and S. sonnei. We show that S. sonnei and each major S. flexneri serotype are comprised of genetically diverse populations, the majority of which were likely introduced into Southeast Asia in the 1970s-1990s. Intranational and regional dissemination allowed widespread propagation of both species across the region. Our data indicate that the epidemiology of S. sonnei and the major S. flexneri serotypes were characterised by frequent clonal replacement events, coinciding with changing susceptibility patterns against contemporaneous antimicrobials. We conclude that adaptation to antimicrobial pressure was pivotal to the recent evolutionary trajectory of Shigella in Southeast Asia.

Correlation between the sulfamethoxazole-trimethoprim resistance of Shigella flexneri and the sul genes.

ABSTRACT: The aim of this study was to discuss the correlation between the sulfamethoxazole-trimethoprim resistance of Shigella flexneri (S. flexneri) and the antibiotic resistance genes sul1, sul2, and sul3 and SXT element.From May 2013 to October 2018, 102 isolates of S. flexneri were collected from the clinical samples in Jinan. The Kirby-Bauer (K-B) test was employed to determine the antibiotic susceptibility of the S. flexneri isolates. The antibiotic resistance rate was analyzed with the WHONET5.4 software. The isolates were subject to the PCR amplification of the sul genes (sul1, sul2, and sul3) and the SXT element. On the basis of the sequencing results, the correlation between the sulfamethoxazole-trimethoprim resistance of the S. flexneri isolates and the sul genes was analyzed.The antibiotic resistance rates of the 102 S. flexneri isolates to ampicillin, streptomycin, chloramphenicol, tetracycline, and sulfamethoxazole-trimethoprim were 90.2%, 90.2%, 88.2%, 88.2%, and 62.7%, respectively. The antibiotic resistance rates of these isolates to cefotaxime, ceftazidime, and ciprofloxacin varied between 20% and 35%. However, these isolates were 100% susceptible to cefoxitin. Positive fragments were amplified from 59.8% (61/102) of the 102 S. flexneri isolates, the sizes of the sul1 and sul2 genes being 338 bp and 286 bp, respectively. The sequence alignment revealed the presence of the sul1 and sul2 genes encoding for dihydrofolate synthase. The carrying rate of the sul1 gene was 13.7% (14/102), and that of the sul2 gene was 48.0% (49/102). No target gene fragments were amplified from the 3 isolates resistant to sulfamethoxazole-trimethoprim. The sul3 gene and SXT element were not amplified from any of the isolates. The testing and statistical analysis showed that the resistance of the S. flexneri isolates to sulfamethoxazole-trimethoprim correlated to the sul1 and sul2 genes.The acquired antibiotic resistance genes sul1 and sul2 were closely associated with the resistance of the 102 S. flexneri isolates to sulfamethoxazole-trimethoprim.

Computational Identification of Essential Enzymes as Potential Drug Targets in Shigella flexneri Pathogenesis Using Metabolic Pathway Analysis and Epitope Mapping.

Shigella flexneri is a facultative intracellular pathogen that causes bacillary dysentery in humans. Infection with S. flexneri can result in more than a million deaths yearly and most of the victims are children in developing countries. Therefore, identifying novel and unique drug targets against this pathogen is instrumental to overcome the problem of drug resistance to the antibiotics given to patients as the current therapy. In this study, a comparative analysis of the metabolic pathways of the host and pathogen was performed to identify this pathogen's essential enzymes for the survival and propose potential drug targets. First, we extracted the metabolic pathways of the host, Homo sapiens, and pathogen, S. flexneri, from the KEGG database. Next, we manually compared the pathways to categorize those that were exclusive to the pathogen. Further, all enzymes for the 26 unique pathways were extracted and submitted to the Geptop tool to identify essential enzymes for further screening in determining the feasibility of the therapeutic targets that were predicted and analyzed using PPI network analysis, subcellular localization, druggability testing, gene ontology and epitope mapping. Using these various criteria, we narrowed it down to prioritize 5 novel drug targets against S. flexneri and one vaccine drug targets against all strains of Shigella. Hence, we suggest the identified enzymes as the best putative drug targets for the effective treatment of S. flexneri.

Shigella sonnei: virulence and antibiotic resistance.

Shigella sonnei is the emerging pathogen globally, as it is the second common infectious species of shigellosis (bloody diarrhoea) in low- and middle-income countries (LMICs) and the leading one in developed world. The multifactorial processes and novel mechanisms have been identified in S. sonnei, that are collectively playing apart a substantial role in increasing its prevalence, while replacing the S. flexneri and other Gram-negative gut pathogens niche occupancy. Recently, studies suggest that due to improvement in sanitation S. sonnei has reduced cross-immunization from Plesiomonas shigelliodes (having same O-antigen as S. sonnei) and also found to outcompete the two major species of Enterobacteriaceae family (Shigella flexneri and Escherichia coli), due to encoding of type VI secretion system (T6SS). This review aimed to highlight S. sonnei as an emerging pathogen in the light of recent research with pondering aspects on its epidemiology, transmission, and pathogenic mechanisms. Additionally, this paper aimed to review S. sonnei disease pattern and related complications, symptoms, and laboratory diagnostic techniques. Furthermore, the available treatment reigns and antibiotic-resistance patterns of S. sonnei are also discussed, as the ciprofloxacin and fluoroquinolone-resistant S. sonnei has already intensified the global spread and burden of antimicrobial resistance. In last, prevention and controlling strategies are briefed to limit and tackle S. sonnei and possible future areas are also explored that needed more research to unravel the hidden mysteries surrounding S. sonnei.

An in-vitro study on a novel six-phage cocktail against multi-drug resistant-ESBL Shigella in aquatic environment.

Shigella spp. are water-borne pathogens responsible for mild to severe cases bacilli dysentery all around the world known as Shigellosis. The progressively increasing of antibiotic resistance among Shigella calls for developing and establishing novel alternative therapeutic methods. The present study aimed to evaluate a novel phage cocktail of lytic phages against extended spectrum beta lactamase isolates of Shigella species in an aquatic environment. The phage cocktail containing six novel Shigella specific phages showed a broad host spectrum. The cocktail was very stable in aquatic environment. The cocktail resulted in about 99% decrease in the bacterial counts in the contaminated water by several species and strains of Shigella such as Shigella sonnei, Shigella flexneri and Shigella dysenteriae. Achieving such a high efficiency in this in-vitro study demonstrates a high potential for in-vivo and in-situ application of this phage cocktail as a bio-controlling agent against Shigella spp. contamination and infections.

Secondary Structural Transformation of Bovine Lactoferricin Affects Its Antibacterial Activity.

Lactoferricin (Lfcin) is a potent antibacterial peptide derived from lactoferrin by pepsin hydrolysis. It was hypothesized that structural transformation of Lfcin could affect its antibacterial function through forming and breaking of intramolecular disulfide bond. To prove this hypothesis, bovine Lfcin (bLfcin) and its two derivatives, bLfcin with a disulfide bond (bLfcin DB) and bLfcin with a mutation C36G (bLfcin C36G), were synthesized, purified, and identified. The circular dichroism (CD) spectra of the peptides were detected in solutions with different ionic and hydrophobic strength. Then, the secondary structure contents of the peptides were calculated on the basis of the CD spectra. The antibacterial activity of the peptides against Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028, Shigella flexneri ATCC 12022, and Staphylococcus aureus ATCC 25923 was evaluated. The results showed that bLfcin and bLfcin C36G had similar percentages of secondary structure in water, while bLfcin and bLfcin DB had similar ratios of secondary structure under less hydrophobic conditions. The synthetic peptides exhibited antibacterial activity against all the tested bacteria, except for S. aureus ATCC 25923. bLfcin demonstrated higher antibacterial activity compared with its derivatives. The results suggested that bLfcin could transform its structure under alterative ionic strengths and hydrophobic conditions, and the transformation of structures was beneficial to enhancing the antibacterial function.

Association of Serotype With Antimicrobial Resistance Patterns Among Shigella flexneri Isolates From Pakistan: The Importance of Serotype 2b.

BACKGROUND: Shigella flexneri is an emerging threat in low socioeconomic countries including Pakistan. No previous data is available on the association between S. flexneri serotypes and antimicrobial resistance in Pakistan. OBJECTIVES: The objective of the present study was to assess the association between serotypes and antimicrobial resistance patterns among S. flexneri isolated from clinical and nonclinical samples. METHODS: A total of 199 S. flexneri isolates were subjected to molecular serotyping and antibiotic resistance. RESULTS: The most prevalent S. flexneri serotype was 2b (38%) followed by 1b (24%), 7a (20%), 2a (11%), 1d (5%) and Y (2%). The phylogenetic reconstruction showed 12 clades among which the clades II, III, V, VIII, IX and XI have consisted of serotypes that were found both in human population and environment samples. A high level of multidrug resistance (MDR) was observed in serotype 2b (37.68%) followed by 1b (19.5%) and 7a (19.5%), 2a (11.5%), 1d (5%) and Y (2%). All isolates of serotype 2b showed high level of resistance to amoxicillin/clavulanic acid (100%) followed by quinolone (74.6%) and trimethoprim-sulfamethoxazole (54.6%). Interestingly, none of the serotype was resistant to piperacillin-tazobactam, imipenem and amikacin. The most frequently detected resistance genes among serotype 2b were blaOXA (100%) followed by qnrS (88%), cat (81%) and sul2 (63%). CONCLUSION: The most frequent S. flexneri serotype was 2b while 1d and Y was first time reported in Pakistan. High frequency of MDR serotypes of S. flexneri is a serious threat in diarrhea endemic regions and thus require urgent strategies for its continuous monitoring and prevention.

Newly Emerged Serotype 1c of Shigella flexneri: Multiple Origins and Changing Drug Resistance Landscape.

Bacillary dysentery caused by Shigella flexneri is a major cause of under-five mortality in developing countries, where a novel S. flexneri serotype 1c has become very common since the 1980s. However, the origin and diversification of serotype 1c remain poorly understood. To understand the evolution of serotype 1c and their antimicrobial resistance, we sequenced and analyzed the whole-genome of 85 clinical isolates from the United Kingdom, Egypt, Bangladesh, Vietnam, and Japan belonging to serotype 1c and related serotypes of 1a, 1b and Y/Yv. We identified up to three distinct O-antigen modifying genes in S. flexneri 1c strains, which were acquired from three different bacteriophages. Our analysis shows that S. flexneri 1c strains have originated from serotype 1a and serotype 1b strains after the acquisition of bacteriophage-encoding gtrIc operon. The maximum-likelihood phylogenetic analysis using core genes suggests two distinct S. flexneri 1c lineages, one specific to Bangladesh, which originated from ancestral serotype 1a strains and the other from the United Kingdom, Egypt, and Vietnam originated from ancestral serotype 1b strains. We also identified 63 isolates containing multiple drug-resistant genes in them conferring resistance against streptomycin, sulfonamide, quinolone, trimethoprim, tetracycline, chloramphenicol, and beta-lactamase. Furthermore, antibiotic susceptibility assays showed 83 (97.6%) isolates as either complete or intermediate resistance to the WHO-recommended first- and second-line drugs. This changing drug resistance pattern demonstrates the urgent need for drug resistance surveillance and renewed treatment guidelines.