Characteristics of Clostridioides difficile colonization in Ilamian children

Background

The increasing colonization with Clostridioides difficile in paediatric hospitalized population is a well known event; however, its prevalence in Iranian children has not effectively been identified yet.

Objective

The objective of this study was to determine the intestinal-carriage rates of C. difficile and molecular characterization of C. difficile in the Ilamian pediatric population from May 22, 2018, until September 22, 2018.

Materials and Methods

Eighty samples were obtained from 40 children aged <5 years, at day 0 of their hospitalization (N=40 samples), to determine community-associated colonization, and then at day 5 days after hospitalization (N=40 samples), to determine healthcare associated colonization. The stool samples were examined for C. difficile, and isolated strains were evaluated for production of Clostridial toxins A/B and molecular characterizations.

Results

The colonization rates of C. difficile and toxigenic C. difficile were 10% (8/80) and 3.75% (3/80), respectively. Based on the age group, the intestinal-carriage rates of C. difficile were 37.5, 50, and 12.5% in children ≤ 1, 1-3, and 3-5 years old, respectively. Our findings have revealed eight distinct ribotypes. Our findings have revealed eight distinct ribotypes of C. difficile isolates. Three out of 8 (37.5%) of C. difficile isolates were considered as community-associated colonization and belonged to ribotypes 7, 8, and 9. Conclusion. Our findings suggest the need of confirmation by further epidemiological studies in Iranian children. Given that the 37.5% of cases observed were community-associated, estimates of the incidence of C. difficile infections, that include only hospitalized children, may largely underestimate the burden of disease in children.

Molecular Cloning and Immunogenicity Evaluation of PpiC, GelE, and VS87_01105 Proteins of Enterococcus faecalis as Vaccine Candidates

Background

Among the enterococci strains, Enterococcus faecalis is considered as one of the important nosocomial pathogens affecting immunocompromised patients. In this study, the immunogenicity of PpiC, GelE, and VS87_01105 proteins against enterococcal infection was investigated in a mice model.

Methods

The genes encoding these proteins were cloned into pET21a expression vector, and the recombinant proteins were produced. Mice and rabbits were immunized with the purified recombinant proteins, and subsequently, mice were challenged with E. faecalis for the evaluation of their survival and bacterial clearances. The antibody responses to recombinant proteins were determined by ELISA assay, and opsonophagocytic activities of the antibodies were also measured. Passive immunization was performed using purified antibodies. Mice were challenged, and their survival and bacterial clearance were determined.

Results

Immunized mice with PpiC, GelE, and VS87_01105 recombinant proteins showed 80%, 70%, and 40% survival rate, respectively. The survival rates among passively immunized mice that received 500 µg of IgG fraction in 100 µl PBS buffer of each of anti-PpiC, anti-GelE, and anti-VS87_01105 were 60%, 50%, and 20%, respectively. The rates of opsonization with anti-PpiC, anti-GelE, and anti-VS87_01105 antibodies at 1/10 dilution were 77%, 64%, and 23%, respectively.

Conclusion

Based on our findings, PpiC, and GelE proteins can protect the mice against E. faecalis ATCC 29212 and effectively induce a protective antibody response. Thus, these proteins could be used as an additional therapeutic tool against enterococcal infections. Further studies to determine the role of PpiC in ligand binding and demonstration of epitope mapping may establish a credible target for vaccination.

Vaccine potential of LenA and LcpA proteins of Leptospira interrogans in combination with Escherichia coli heat-labile enterotoxin, B subunit (LTB)

BACKGROUND AND OBJECTIVES

Leptospirosis is a zooanthroponosis caused by the genus of Leptospira. It is an emerging public health problem due to its increasing incidence. The achievement to a vaccine that prevent from entrance of Leptospira interrogans to the deeper tissues of the host is needed. This study aimed to investigate the immunogenicity of LcpA (rLcpA) and LenA (rLenA) recombinant proteins in combination with LTB (rLTB) recombinant protein as an adjuvant against leptospiral infection in hamsters.

MATERIALS AND METHODS

The genes encoding these proteins were cloned into pGH cloning vector and then lenA, lcpA and ltb genes subcloned into pET-15b and pET-28a expression vectors, respectively. The hamsters were immunized with the purified recombinant proteins and challenged with Leptospira interrogans for evaluation of their survival. The antibody responses to the recombinant proteins were determined by ELISA. Then, data entered into SPSS software. Statistical Kruskal-Wallis test was used to compare the significant differences among different groups. The groups with significant differences were further analyzed by post hoc tests. The p value < 0.05 statistically was considered significant.

RESULTS

Immunized hamsters with rLenA-plus-rLTB, rLcpA-plus-rLTB and rLenA-plus-rLcpA-plus-rLTB proteins showed 60%, 74%, and 80% survival rates, respectively. A significant amount of interleukin-17 (IL-17), interleukin-4 (IL-4) and gamma interferon (IFNγ) cytokines were produced in immunized hamsters.

CONCLUSION

Based on our findings, rLcpA and rLenA proteins in combination with rLTB can protect the hamsters against L. interrogans and effectively induce a protective antibody response. Thus, these proteins can be used as an additional prophylactic tool against leptospira.

CbpM and CbpG of Streptococcus Pneumoniae Elicit a High Protection in Mice Challenged with a Serotype 19F Pneumococcus

Among many pneumococcal antigens, choline-binding proteins (CPBs) display a high immunogenicity in animal models. This study aims to determine the immunogenicity of CbpM, CbpG and CbpL proteins of Streptococcus pneumoniae in a mice model. The genes were cloned into pET21a expression vector and the recombinant proteins were produced. Mice were immunized with the purified recombinant proteins. Subsequently, the mice were challenged with S. pneumoniae ATCC 49619 (2×106 CFU) and their survival and bacterial clearances were followed 24 hours after infection. The antibody responses of the mice were determined by ELISA assay. The opsonophagocytosis assay was performed using rabbit's sera. Passive immunization was carried out using two doses of anti-CbPs antibodies. Finally, these mice were  experimentally infected with virulent bacteria and the protective effects of two doses of 10 and 100 µg/mL by monitoring the survival rate and bacterial clearance were determined at 2, 3 and 7 days after bacterial challenge. The mice actively immunized with CbpM, CbpG and CbpL recombinant proteins showed survival rate of 100%, 85% and 75%, respectively. The survival rates among passively immunized mice groups which received 100 µg/mL dose of anti-CbpM, anti-CbpG and anti- CbpL were 50%, 50% and 25%, respectively. The rates of opsonization with rabbit's antibodies against CbpM, CbpG, and CbpL  at 100 µg/mL doses was 45.6%, 14.7% and 82.3%, and at 10 µg/mL was 12.9%, 12.2% and 9.35%, respectively. Our findings suggest that the recombinant proteins particularly CbpM and CbpG can protect the mice against pneumococcus19F serotype and effectively induce a protective antibody response. Thus, CbpG and CbpM proteins might be used as suitable vaccine candidate in pneumococcal vaccine formulations.

Characterization of virulence genes, serogroups and antimicrobial susceptibility of Shiga toxin producing Escherichia coli isolated from bovine mastitic milk in Tehran, Iran

Clinical mastitis caused by Enterobacteriaceae accounts for significant economic loss in dairy herds. One of the important pathogens that causes mastitis is Shiga toxinproducing Escherichia coli (STEC). Moreover, mastitis caused by STEC can be considered as a source of transmission of STEC strains to humans through unpasteurized milk. The aim of the current study was to determine of the prevalence, the identification of serogroups, the molecular characterization of virulence factors, and the antibiotic resistance properties of STEC isolates from bovine mastitic milk in dairy cattle in Tehran. A total of 325 milk samples from dairy cattle with clinical signs of mastitis were collected. All E. coli isolates (n: 87, 26.7%) were subjected to multiplex PCR for the detection of stx1, stx2, eaeA, and ehly genes and serogroups. Antibiotic susceptibility testing was carried out by the disc diffusion method for all the STEC isolates. Eighty-seven (26.8%) E. coli and 9 (2.8%) STEC strains were isolated from the bovine mastitic milk samples. Shiga-like toxin genes (stx1 and stx2 or one of them), eaeA and ehly were detected in 100%, 66.6%, and 33.3% of STEC isolates, respectively. O26 (22.2%) and O111 (22.2%) were the most commonly detected STEC serogroups. Other serogroups included O145, O121, O128, O157 and O113. High resistance rate to ampicillin and tetracycline (100%) was observed, followed by trimethoprim/sulfamethoxazole (66.6%) and chloramphenicol (55.5%). STEC isolates were found in bovine mastitic milk in Tehran and most of the STEC isolates in our study were non-O157 strains.

A systematic study on the use of ultrasound energy for the synthesis of nickel-metal organic framework compounds

A nickel metal-organic framework (Ni-MOF) was successfully synthesized using ultrasound irradiation. Further to this, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and nitrogen adsorption [i.e. Brunauer-Emmett-Teller (BET) Surface Area Analysis] techniques were used to characterize the synthesized Ni-MOF. In addition, the effect of sonication on the surface area, pore diameter and pore volume of the final product was systematically studied using Taguchi technique. The experiments ascertained that manufacturing of the Ni-MOF by means of the ultrasonic-assisted technique is feasible at a relatively shorter time compare to the conventional methods. The final product showed more uniform shape distribution and improved BET properties. The obtained results offered that the synthesized Ni-MOF samples could be used in several applications.

Molecular characterization of the first community-acquired methicillin-resistant Staphylococcus aureus strains from Central Iran

BACKGROUND

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has spread throughout the world with varying regional incidences and different staphylococcal cassette chromosome mec (SCCmec) elements in different genetic backgrounds. No information is available on CA-MRSA in Iran. A cross-sectional study was carried out among healthy students to investigate: (1) the prevalence of CA-MRSA in Central Iran, (2) the molecular epidemiology of such CA-MRSA strains, (3) the antimicrobial resistance patterns of the strains, and (4) the distribution of virulence genes in these CA-MRSA strains.

METHODS

A total of 700 nasal swabs were collected and subjected to S. aureus and MRSA-specific isolation procedures. Antimicrobial resistance patterns were determined using the disk diffusion method, and molecular typing was carried out by multi-locus sequence typing (MLST), SCCmec typing, and Staphylococcus protein A (spa) typing for all CA-MRSA isolates. PCR was used to detect various virulence genes.

RESULTS

One hundred fifty-four S. aureus strains were isolated from the anterior nares of 700 healthy students. According to the US Centers for Disease Control and Prevention definitions for CA-MRSA, seven (4.5%) isolates were confirmed as CA-MRSA. CA-MRSA isolates belonged to SCCmec types IV (n = 6) and V (n = 1). The predominant spa-type among the CA-MRSA isolates was t790 (n = 3), with single t660, t084, and t325 isolates; one isolate was not typeable. The predominant sequence type was ST22, t790, SCCmec IV in three isolates, and the four other sequence types were ST25, ST859, ST14, and ST15.

CONCLUSIONS

Iranian CA-MRSA strains are genetically diverse with an elevated prevalence of t790/ST22 SCCmec IV isolates. These findings support the need for more effective infection control measures to reduce nasal carriage and prevent dissemination of CA-MRSA in Iran.

The use of clinoptilolite and its sodium form for removal of radioactive cesium, and strontium from nuclear wastewater and Pb2+, Ni2+, Cd2+, Ba2+ from municipal wastewater

Three different samples of Iranian natural zeolites (clinoptilolite) and its sodium exchanged forms have been investigated for uptaking several different cations. Ion-exchange isotherms, have been given and discussed.