Toxigenic Strains Research Articles

Characterization of Shiga toxin-producing Escherichia coli isolated from cattle and their contacts

Objective:To estimate the occurrence of Shiga toxin-producing E. coli (STEC) in cattle reared on farms versus those belonged to smallholders as well as their contact keepers. Design: Descriptive study. Samples: The study comprised 260 samples consisting of f ninety each of (n = 90) for each of cattle feces and milk samples that were originated either from smallholding cattle (n=30) or from farm cattle (n=60) alongside eighty stool specimens were collected from smallholders contacts (n=50) and farm workers (n=30). Procedures: All samples were examined using conventional bacteriological and molecular techniques. Results: The overall occurrence of E. coli in animal samples was 25/180 with a percentage of 13.9. In cattle feces, it was 14.4% (13/90), whereas it was 13.3% (12/90) in milk samples. In human stool samples, E. coli i isolates were also identified in smallholders’ contacts (14%, 7/50) and farm workers (16.7%, 5/30). The most prevalent serotypes obtained from farm cattle and their keepers were (O157 and O55) and from smallholders’ cattle and their contact were (O111, O157, and O11). The PCR analysis showed that stx2 wasthe most predominant genotypes followed by stx1. The recovered E. coli isolates showed high resistance to penicillin G (97.3%) and 81% (30/37) of the tested strains exhibited multidrug resistance. Conclusion and clinical relevance: the presence of Shiga toxigenic and multiple drug-resistant strains of E. coli in the study area poses a high potential risk. Hence, strict hygienic measures should be followed to reduce the risk of STEC occurrence in smallholding cattle and those in commercial farms.

High contamination rates of shoes of veterinarians, veterinary support staff and veterinary students with Clostridioides difficile spores.

Clostridioides difficile is often found in animals and their environment. However, not much has been reported on veterinary clinics environment in terms of the spore load, prevalence and PCR ribotype diversity. The aim of this study was to assess the prevalence of C. difficile on shoe soles of veterinarians, veterinary support staff and veterinary students at the Veterinary Faculty campus. Altogether, 50 shoe sole swabs were collected, and the positivity rates ranged from 86.7% in swabs from veterinarians to 100% in swabs from support staff and students. Non‐toxigenic and toxigenic strains representing toxinotypes 0, IV and XIX were isolated and distributed into 17 different PCR ribotypes, most common being 010, 014/020, SLO002 and 009. PCR ribotype 010 was the most prevalent and isolated from shoe soles sampled in 6/7 areas. Students' shoes had highest ribotype diversity (15/17 PCR ribotypes) but showed a low overlap with ribotype isolated from vets and support staff shoes. Veterinary students are likely the main vectors of C. difficile spores transmissions among veterinary teaching clinics and the hospital.

Comparison of Host Cytokine Response in Piglets Infected With Toxigenic and Non-toxigenic Staphylococcus hyicus.

Staphylococcus hyicus is the most common causative agent of exudative epidermitis (EE) in piglets. Staphylococcus hyicus can be grouped into toxigenic and non-toxigenic strains based on its ability to cause EE in pigs. However, the inflammatory response of piglets infected with toxigenic and non-toxigenic S. hyicus has not been elucidated. In this study, we evaluated the serum cytokine profile in piglets inoculated with toxigenic and non-toxigenic S. hyicus strains and recorded the clinical signs in piglets. Fifteen piglets were divided into three groups (n = 5) and inoculated with a toxigenic strain (ZC-4), a non-toxigenic strain (CF-1), and PBS (control), respectively. The changes in serum levels of cytokines (interleukin [IL]-1β, IL-4, IL-6, IL-8, IL-10, IL-12, granulocyte-macrophage colony-stimulating factor, interferon-γ, transforming growth factor-β1, and tumor necrosis factor-α) were evaluated using a cytokine array at 6, 24, 48, and 72 h post inoculation. The results showed that piglets infected with the toxigenic strain exhibited more severe clinical signs and higher mortality than those infected with the non-toxigenic strain. The serum levels of pro-inflammatory cytokine IL-1β were significantly increased in toxigenic-and non-toxigenic-strain-infected piglets compared to those in the control group (p < 0.05), while the anti-inflammatory cytokine IL-10 was significantly up-regulated only in toxigenic group than in control group (p < 0.05). These results indicated that piglets infected with toxigenic and non-toxigenic S. hyicus showed differential infection status and inflammatory responses. Both toxigenic- and non-toxigenic- S. hyicus infection could induce a pro-inflammatory reaction in piglets. In addition, the toxigenic strain induced a strong anti-inflammatory response in piglets as indicated by the increased serum level of IL-10, which may be associated with the severe clinical signs and increased mortality and may be the key cytokine response responsible for pathogenic mechanisms of S. hyicus.

Enrichment of deoxynivalenol and establishment of online early warning treatment system for drinking water

AbstractAn online monitoring and early warning system was established to detect drinking water pollution from deoxynivalenol (DON). Flow injection chemiluminescence was selected as online monitoring tool for its low detection limit, fast detection process and broad linear range. The toxigenic strain of Fusarium graminearum (GDMCC3.507, freeze‐dried powder) was incubated and grown on potato dextrose agar (PDA) culture medium under constant temperature of 26 °C for 5 days. Different culture conditions were investigated to determine the most suitable conditions to culture the fungi and enrich DON that produced by Fusarium graminearum. Powder activated carbon (PAC) was used to remove DON in drinking water. A dynamic threshold X ± 5SD was established to detect DON in drinking water effectively. Calculation of standard curve indicated that 6 mg DON could be easily extracted from 100 mg corn culture medium. Emergency detoxification was achieved by PAC and the removal rate reached 76% after 50 min of adsorption process. Once the chemiluminescence intensity exceeded the X ± 5SD value of the exact point during the monitoring process, the tap water was estimated to have excessive toxin. The establishment of this emergency system could provide a basis for dealing with sudden pollution of drinking water.

Molecular diagnostic of toxigenic Corynebacterium diphtheriae strain by DNA sensor potentially suitable for electrochemical point-of-care diagnostic

The presented study is focused on the development of electrochemical genosensor for detection of tox gene fragment of toxigenic Corynebacterium diphtheriae strain. Together with our previous studies it fulfils the whole procedure for fast and accurate diagnostic of diphtheria at its early stage of infection with the use of electrochemical methods. The developed DNA sensor potentially can be used in more sophisticated portable device. After the electrochemical stem-loop probe structure optimization the conditions for real asymmetric PCR (aPCR) product detection were selected. As was shown it was crucial to optimize the magnesium and organic solvent concentrations in detection buffer. Under optimal conditions it was possible to selectively detect as low as 20.8 nM of complementary stand in 5 min or 0.5 nM in 30 min with sensitivity of 12.81 and 0.24 1⋅μM−1 respectively. The unspecific biosensor response was elucidated with the use of new electrode blocking agent, diethyldithiocarbamate. Its application in electrochemical genosensors lead to significant higher current values and the biosensor response even in conditions with magnesium ion depletion. The developed biosensor selectivity was examined using samples containing genetic material originated from a number of non-target bacterial species which potentially can be present in the human upper respiratory tract.

Increased Risk of Severe Gastric Symptoms by Virulence Factors vacAs1c, alpA, babA2, and hopZ in Helicobacter pylori Infection.

Two virulence factors of Helicobacter pylori, cagA and vacA, have been known to play a role in the development of severe gastric symptoms. However, they are not always associated with peptic ulcer or gastric cancer. To predict the disease outcome more accurately, it is necessary to understand the risk of severe symptoms linked to other virulence factors. Several other virulence factors of H. pylori have also been reported to be associated with disease outcomes, although there are many controversial descriptions. H. pylori isolates from Koreans may be useful in evaluating the relevance of other virulence factors to clinical symptoms of gastric diseases because the majority of Koreans are infected by toxigenic strains of H. pylori bearing cagA and vacA. In this study, a total of 116 H. pylori strains from Korean patients with chronic gastritis, peptic ulcers, and gastric cancers were genotyped. The presence of virulence factors vacAs1c, alpA, babA2, hopZ, and the extremely strong vacuolating toxin was found to contribute significantly to the development of severe gastric symptoms. The genotype combination vacAs1c/alpA/babA2 was the most predictable determinant for the development of severe symptoms, and the presence of babA2 was found to be the most critical factor. This study provides important information on the virulence factors that contribute to the development of severe gastric symptoms and will assist in predicting clinical disease outcomes due to H. pylori infection.

Comparison of adult vs. paediatric inpatients with staphylococcal scalded skin syndrome: a retrospective database analysis

Dear Editor, Staphylococcal scalded skin syndrome (SSSS) is a rare dermatologic disease caused by toxigenic strains of Staphylococcus aureus. Adult SSSS is less common than pediatric cases of the disease, likely due to the development of immunity early in life, but has a higher fatality rate 1-3 . These facts hint at the different clinical nature of SSSS between patients of different ages.

Multidrug resistant staphylococci isolated from pigs with exudative epidermitis in North eastern Region of India.

Exudative epidermatitis or greasy pig disease (GPD) is a contagious disease of pig and endemic worldwide caused by toxigenic strains under genus Staphylococcus. The present study reported an outbreak of GPD in Champhai district of Mizoram adjoining to the southern border of Myanmar. A total of 60 samples were collected from 22 clinically affected animals and processed for isolation and identification of Staphylococcus spp. All the isolates were subjected to antimicrobial sensitivity assay, biofilm production assay and detection of virulence genes, biofilm genes and mec genes followed by cloning and sequencing for phylogenetic analysis. A total of 44 staphylococci belonged to four species (S. sciuri, S. aureus,S. lentus, and S. hyicus) were isolated. Majority of the isolates were multidrug resistant with maximum resistance against ampicillin, penicillin including vancomycin. None of the S. hyicus isolates was methicillin resistant (MRSH) but 66·67% isolates were MRSA. By PCR, mecA gene was detected in S. aureus (n=2), S. sciuri (n=4) and S. lentus (n=3). Biofilm associated gene icaD was detected in S. aureus (n=3), S. sciuri (n=5), S. hyicus (n=4) and S. lentus (n=6). The exfoliative toxin genes (ehxB, shetA and tsst1) were detected in S. hyicus (n=3) and S. aureus (n=1) isolates. All the isolates were closely related with the isolates from pigs of China, Germany, Japan and USA. The pathogens might be transmitted through illegal migration of pigs from Myanmar to India.

Diarrhea associated with Clostridium difficile in the oncology clinic

Purpose of the study. To conduct typing of toxigenic strains of Clostridium difficile, obtained from oncological patients who are in hospital.Material and Methods. The study included 130 patients with Clostridium difficile – associated diarrhea. First, the presence of toxins A+B+ in the feces was determined by enzyme immunoassay on an automatic miniVidas analyzer from BioMieux SA (France). For screening using real-time PCR, 26 toxigenic Clostridium difficile were selected. For the study used the system GeneXpert company «Cepheid» (Sweden).Results. Of the 1287 patients with diarrhea who were treated in an oncologic hospital, 130 (10,1%) tested positive for toxin A+B+ Clostridium difficile. For the study using real-time PCR, 26 samples were taken. The average age of patients is 57 years. 10 (38,5%) toxigenic strains were identified as hypervirulent ribotype. 7/10 strains were isolated for 3 consecutive month. The average age of patients with hypervirulent strains was 45 years. Patients participating in the study, in most cases were from the surgical departments – 61,5%, from the therapeutic – 34,7%.Conclusion. The study showed that the prevalence of Clostridium difficile infection in our clinic is lower than in other countries. Although hypervirulent strains accounted for 1/3 of all typed Clostridium difficile, special attention should be paid to them. Delayed diagnosis, delay in the onset of specific therapy in cancer patients can lead to a deterioration in the quality of life and in some cases be fatal. PCR diagnostics can determine the hypervirulent ribotype and carry out epidemiological measures aimed at preventing local outbreaks in the hospital.

Assessment of nanoencapsulated Cananga odorata essential oil in chitosan nanopolymer as a green approach to boost the antifungal, antioxidant and in situ efficacy

In this study, a comparative efficacy of Cananga odorata EO (CoEO) and its nanoencapsulated formulation into chitosan nanoemulsion (CoEO-CsNe) against a toxigenic strain of Aspergillus flavus (AF-M-K5) were investigated for the first time in order to determine its efficacy in preservation of stored food from fungal, aflatoxin B1 (AFB1) contamination and lipid peroxidation. GC and GC–MS analysis of CoEO revealed the presence of linalool (24.56%) and benzyl acetate (22.43%) as the major components. CoEO was encapsulated into chitosan nanoemulsion (CsNe) through ionic-gelation technique and characterized by High Resolution-Scanning Electron Microscopy (HR-SEM), Fourier Transform Infrared spectroscopy (FTIR), and X-Ray Diffraction (XRD) analysis. The CoEO-CsNe during in vitro investigation against A. flavus completely inhibited the growth and AFB1 production at 1.0 μL/mL and 0.75 μL/mL, respectively. Additionally, CoEO-CsNe showed improved antioxidant activity against DPPH• and ABTS•+ with IC50 value 0.93 and 0.72 μL/mL, respectively. Further, CoEO-CsNe suppressed fungal growth, AFB1 secretion and lipid peroxidation in Arachis hypogea L. during in situ investigation without causing any adverse effect on seed germination. Overall results demonstrated that the CoEO-CsNe has potential of being utilized as a suitable plant based antifungal agent to improve the shelf-life of stored food against AFB1 and lipid peroxidation mediated biodeterioration.

Microcystis species and their toxigenic strains in phytoplankton of ten Bulgarian waterbodies

The summer phytoplankton structure of ten Bulgarian waterbodies was studied by HPLC analysis of marker pigments, light microscopy (LM) and PCR amplification of mcyB and mcyE gene sequences. The aim was to detect biodiversity and spread of toxigenic strains of potential microcystin producers and the important bloom-forming genus Microcystis in particular. The screening was done in three waterbodies, where Microcystis had already been found (Lakes Ezerets and Durankulak and Reservoir Koprinka), three waterbodies from which it had not been reported (Reservoirs Shilkovtsi, Zhrebchevo, Suedinenie) and four reservoirs that were sampled for the first time (Malka Smolnitsa, Plachidol 2, Preselka, Duvanli). LM and HPLC data similarly showed that cyanoprokaryotes contributed significantly to the total phytoplankton composition (29%) and biomass (15–87%) in nine sampled waterbodies. Microcystis aeruginosa, M. natans, M. smithii, M. wesenbergii, Microcystis spp., M. cf. comperei and M. pseudofilamentosa, were identified using LM (the last two tropical species were found for the first time in the country). Despite the low contribution of Microcystis to the phytoplankton diversity (1–4 taxa per sample) and to the total phytoplankton biomass (&lt; 0.01–0.5%), 57 toxigenic strains of this genus were revealed by PCR, most of which demonstrated high similarity with NCBI M. aeruginosa and M. wesenbergii strains.

The Relative Role of Toxins A and B in the Virulence of Clotridioides difficile.

Most pathogenic strains of C. difficile possess two large molecular weight single unit toxins with four similar functional domains. The toxins disrupt the actin cytoskeleton of intestinal epithelial cells leading to loss of tight junctions, which ultimately manifests as diarrhea in the host. While initial studies of purified toxins in animal models pointed to toxin A (TcdA) as the main virulence factor, animal studies using isogenic mutants demonstrated that toxin B (TcdB) alone was sufficient to cause disease. In addition, the natural occurrence of TcdA−/TcdB+ (TcdA−/B+)mutant strains was shown to be responsible for cases of C. difficile infection (CDI) with symptoms identical to CDI caused by fully toxigenic (A+/B+) strains. Identification of these cases was delayed during the period when clinical laboratories were using immunoassays that only detected TcdA (toxA EIA). Our hospital laboratory at the time performed culture as well as toxA EIA on patient stool samples. A total of 1.6% (23/1436) of all clinical isolates recovered over a 2.5-year period were TcdA−/B+ variants, the majority of which belonged to the restriction endonuclease analysis (REA) group CF and toxinotype VIII. Despite reports of serious disease due to TcdA−/B+ CF strains, these infections were typically mild, often not requiring specific treatment. While TcdB alone may be sufficient to cause disease, clinical evidence suggests that both toxins have a role in disease.

Identification of chironomid species as natural reservoirs of toxigenic Vibrio cholerae strains with pandemic potential.

Vibrio cholerae causes the fatal cholera diarrhea. Chironomids (Diptera; Chironomidae) are abundant in freshwater aquatic habitats and estuaries and are natural reservoirs of V. cholerae. Until now, only the non-O1/O139 serogroups of V. cholerae were identified in chironomids. Here, we explored whether chironomids are natural reservoirs of V. cholerae O1/O139 serogroups, which are associated with cholera endemics and pandemics. All four life stages of chironomids were sampled from two rivers, and a laboratory culture in Pune, India, and from a pond in Israel. In total, we analyzed 223 chironomid samples. The presence of V. cholerae O1/O139 serogroups was verified using molecular tools. Nine chironomid species were identified; of them, Chironomus circumdatus was the most abundant. The presence of V. cholerae serogroup O1 and the cholera toxin genes were detected in samples from all chironomid species. However, serogroup O139 was detected in only two chironomid species. Besides PCR to detect specific genes, a metagenomic analysis that was performed in three selected C. ramosus larvae, identified a list of virulence genes associated with V. cholerae. The findings provide evidence that chironomids are natural reservoirs of toxigenic V. cholerae O1/O139. Chironomid populations and V. cholerae show biannual peak patterns. A similar pattern is found for cholera epidemics in the Bengal Delta region. Thus, we hypothesize that monitoring chironomids in endemic areas of the disease may provide a novel tool for predicting and preventing cholera epidemics. Moreover, serogroup O139 was detected only in two chironomid species that have a restricted distribution in the Indian subcontinent, possibly explaining why the distribution of the O139 serogroup is limited.

Elucidation of antifungal and aflatoxin B1 inhibitory mode of action of Eugenia caryophyllata L. essential oil loaded chitosan nanomatrix against Aspergillus flavus

The present study investigated the novel antifungal, and anti-aflatoxin B1 mechanism of Eugenia caryophyllata L. essential oil (ECEO) loaded chitosan nanomatrix against the toxigenic strain of A. flavus (AFLV-DK-02). Phytochemical profiling of ECEO was done by GC–MS which revealed eugenol (73.6%) as the primary bioactive compound. ECEO was encapsulated inside the chitosan nanomatrix (ECEO-Np) and characterized using SEM, AFM, FTIR and XRD analysis. The ECEO-Np exhibited enhance antifungal (0.25 μL/mL) and anti-aflatoxin B1 inhibitory activity (0.15 μL/mL) than ECEO. Antifungal and antiaflatoxin B1 inhibitory activity was found to be related with impairment in the biological functioning of the plasma membrane (ergosterol synthesis, leakage of membrane ions, UV light (260, 280 nm) absorbing material, dead cell by propidium iodide assay, mitochondrial membrane potential (MMP), methylglyoxal and inhibition in essential carbon substrate utilization). ECEO-Np exhibited remarkable free radical scavenging activity with IC50 value of 0.002 μL/mL. ECEO-Np effectively preserves the sensory characteristics of exposed maize crop seed up to six months of storage and shows considerable safety profile (non-toxic, non-mutagenic, non-hepatotoxic, non-carcinogenic, non-tumorigenic and biodegradable) using computational ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis.

Impact of the introduction of nucleic acid amplification testing on Clostridioides difficile detection and ribotype distribution in Wales

ObjectivesTo determine the impact of the 2018 introduction of nucleic acid amplification tests (NAATs) for C. difficile detection on the laboratory diagnosis of C. difficile infection (CDI), and the distribution of C. difficile ribotypes. MethodsA retrospective analysis of five years (2015–2019) of C. difficile diagnostic laboratory and PCR ribotyping test results. ResultsA total of 255,104 diagnostic results, from 136,353 patients were analysed: 199,794 samples where glutamate dehydrogenase (GDH) was used as the primary screen; and 55,310 where NAATs were employed. An overall decrease in frontline positivity from 2015 to 2019 (10.3% [n = 5017] to 6% [n = 3190] - p < 0.0001) was observed, despite an increase in the number of samples tested (48,778 to 52,839). NAAT positivity was lower than GDH (p < 0.0001) for the two years where it was implemented. The variance was accounted for by increased overall C. difficile isolation and reduced toxin negative strain culture from NAAT positive samples (p < 0.0001). Ribotype distribution (6546 samples) remained stable with decreasing RT27 isolation in each year except 2017 (p < 0.0001). RT78 was associated with toxin A/B EIA positivity (p < 0.0001). ConclusionsUse of NAAT for the detection of C. difficile, as part of a 2-step algorithm, has not led to an increase in CDI laboratory diagnostic test positivity. In spite of ribotype distribution being comparable for screening in toxin A/B positive samples, there is a significantly greater correlation between NAAT positivity and culture of toxigenic strains compared to GDH.

Diphtheria: characteristics of the pathogen and laboratory diagnostics (lecture).

The problem of diphtheria infection remains relevant, since the circulation of toxigenic strains of Corynebacterium diphtheriae persists in the body of bacterial carriers, despite ongoing vaccination. The lecture presents modern ideas about the properties of the pathogen, its pathogenicity factors (toxin, pili, surface proteins (67-72P (or DIP0733), DIP1281, etc.) and their role in the pathogenesis of the disease.. Information about the clinical and epidemiological characteristics and modern methods of laboratory diagnostics of diphtheria is presented. The algorithm of bacteriological research and methods for determining the toxigenic properties of the pathogen are described. The basics of diphtheria vaccination as the only effective means of preventing mass outbreaks of this disease are considered in the framework of the proposed lecture. Knowledge of the peculiarities of the circulation of strains of Corynebacterium diphtheria in modern conditions, pathogenetic and clinical-epidemiological features of diphtheria, as well as modern methods of laboratory diagnostics is important and necessary for students of medical schools and infectious diseases doctors, pediatricians, bacteriologists, therapists, pulmonologists, epidemiologists, etc.

Laboratory surveillance of paediatric Clostridium difficile infections in healthcare and community settings in Australia, from 2013 to at present

Background: Clostridium difficile is a common antimicrobial-resistant bacterium in healthcare and community settings. C. difficile colonises the gastrointestinal tract and proliferates as a result of the disruption to microbiota from antimicrobial exposure. Increasing rates of hospital and community-acquired C. difficile infections (CA-CDI) in children have been recorded in many parts of the world, however, research in Australia has been limited. The C. difficile Antimicrobial Resistance Surveillance (CDARS) study is a longitudinal investigation of both the molecular epidemiology and antimicrobial resistance phenotype of C. difficile isolated in Australia since 2013. Here we report the molecular characterization of C. difficile isolated from paediatric patients during this period. Methods & Materials: C. difficile isolates (or PCR positive stool samples) were sent from 10 laboratories (one private and one public laboratory) across five states in Australia. Isolates were characterized by PCR for toxin genes and ribotyping. Results: Of the 1542 isolates recovered throughout the study period (August–September 2013–February–March 2018), 127 (8.2%) were from paediatric patients with ages ranging from <1 to 17 years. Overall, 88.2% of isolates (n = 112) were toxigenic (A+B+CDT−, n = 104; A+B+CDT+, n = 6; A−B+CDT−, n = 2). A total of 38 different RTs were identified of which two were novel. The most common RTs isolated were toxigenic RTs 014/020, 002, 046 and 056. Interestingly, RT 027 was isolated from an 11-year-old patient in a public hospital in Queensland. Conclusion: The presence of highly diverse strains in paediatric patients from both hospitals and community-based healthcare establishments suggests the possibility of patients acquiring infections from sources/reservoirs external to the hospital contributing to the rise in CA-CDIs in Australia in recent years. The presence of toxigenic strains, especially the well-established (in both humans and animals) RT 014/020, and the strain commonly found in the Asia-Pacific region, RT 017, is of interest. Additional whole genome sequencing studies will enhance our understanding of the significance of isolating C. difficile from young children (primarily toxigenic strains that are commonly found in other sources/reservoirs such as the environment, food, animals and the elderly).

STUDY OF ANTIFUNGAL ACTIVITY OF LEAF EXTRACT OF SOME WILD PLANTS OF ASTERACEAE ON ASPERGILLUS FLAVUS

Aflatoxins have great significance due to health hazards to men and other useful animals. The aflatoxins are produced by Aspergillus flavus and A. parasiticus. Recently, the use of natural products like cinnamon and clove oil has also been suggested for the inhibition of aflatoxin production as well as growth of A. parasiticus. In view of the known antifungal properties of plant extracts, an attempt has been made in the present investigation to explore the Antifungal Activity of Plant extracts against growth of A. flavus by some wild plants of family Asteraceae, viz., Ageratum conyzoides, Carthamus oxycantha, Eclipta alba, Echinops echinatus, Launea nudicaulis, Lactuca dissecta, Parthenium hysterophorus, Sonchus aspera, Vernonia cinerea and Xanthium strumarium have been studied against growth of toxigenic strain of A. flavus by standard cup method on solid medium. The diameter of zone of inhibition was measured in mm and percent inhibition in growth was calculated. Out of three concentrations viz., 10, 15 and 20 per cent of leaf extracts, the 20 per cent concentration was found most effective. Further, hot water extract of leaf was adjudged more inhibitory as compared to cold water extract of plants. The maximum inhibition (70%) in growth of test fungus was caused by hot water leaf extract of A. conyzoides. It also can be concluded that leaf extract of different experimental plants have antifungal activity to varying extents.

Laboratory Protocols for Isolation and Identification of Toxigenic Strains of Vibrio cholerae: A Review

Vibrio cholerae is a pathogenic bacteria that accounts for diarrheal illness which can be life-threatening in lack of treatment and accounts for great morbidity and mortality. The common mode of transmission includes fecal-oral route transmission mediated through contaminated food and water. The strains 01 and 0139 have been associated with epidemic outbreak of cholera with severe clinical manifestation whereas the infection caused by non O1 and non O139 strains are recognized as non-epidemic cholera characterized by mild-severe diarrheal syndrome without epidemic potential. Laboratory diagnosis through Culture and determining Antimicrobial susceptibility tests are recommended for diagnosis of cholera in all clinical laboratory settings. The simple conventional laboratory diagnosis through culture should be effective for diagnosis of cholera in the resource (PCR) limited laboratories. However, Vibrio cholerae in VBNC (Viable but non-culturable) state can only be detected through molecular methods. Therefore, molecular methods need to be extended in all epidemiological laboratories for preventing misidentification of Vibrio cholerae especially from environmental samples. Epidemic outbreak of cholera has explained the need of immediate preparedness with preventive, diagnosis and curative improvement in all health sectors. Therefore, immediate health and sanitation related awareness are necessary for prompt control of the disease before it leads community to global burden.

Carriage of Clostridioides difficile in healthy infants in the community of Handan, China: A 1-year follow-up study

ObjectiveClostridioides difficile may colonize healthy infants and young children asymptomatically and for the long-term. C. difficile genotypes and the rate and determinants of colonization differ substantially and vary among countries and regions. A 1-year follow-up study was performed to determine the incidence, kinetics and influencing factors of C. difficile intestinal colonization. MethodsTwenty-nine healthy infants (14 girls and 15 boys) living at home with their parents in Handan City were followed by survey from birth to 1 year of age, specifically from October 2014 through December 2015. C. difficile isolates were typed by PCR ribotyping and analyzed for the presence of toxin genes. ResultsDuring the follow-up study period in the first year of life, 20 of the 29 total enrolled infants acquired C. difficile. A total of 437 fecal samples were obtained, and 111 (25.4%) samples contained C. difficile, including 79 (71.2%) toxigenic strains. The toxigenic isolates comprised six PCR ribotypes, and two PCR ribotypes were identified as nontoxigenic strains. ConclusionOur study showed that C. difficile colonization increase with age during the 12-month period, and the dominant toxigenic types of C. difficile isolates in infants were those involved in long-term colonization. Feeding patterns may affect the dynamic progress of C. difficile colonization.