Topical Treatment of Second-Degree Burn Wounds with Lactobacillus plantarum Supernatant: Phase I Trial.

Background & Objective: A burn wound is sterile immediately after injury, but opportunistic bacteria colonize the wound within 48 to 72 hours after the burn, causing delayed or failed burn wound healing. In addition, the presence of multidrug-resistant (MDR) pathogens doubles the treatment problems. Lactobacillus plantarum (L. plantarum) is a well-known antibacterial and healing agent that could be used topically to treat burn wounds. Case Series Presentation: This clinical trial study (Case Series) was performed on 20 patients with deep second-degree burns. Patients had bilateral wounds; the wound on one side of the body was considered as control (treated with silver sulfadiazine) and the other side of the body as treatment (treated with bacteria-free supernatants (BFS) of L. plantarum). The wounds were evaluated by microbial assessments and assessments related to healing. Pseudomonas aeruginosa, Klebsiella pneumonia, and Staphylococcus aureus were isolated from 4 (22.2%), 0%, and 2 (11.1%) of wounds treated with L. plantarum on the fifth day of the treatment, respectively. Furthermore, 12 (66.7%) of wounds treated with L. plantarum were free from bacteria. The need for skin grafting was the same in both treatment and control groups, but graft rejection in the group treated with L. plantarum was (0%) (P=0.02). Conclusion: Regarding eliminating or reducing infection and wound healing, bacteria-free supernatants of L. plantarum can be considered a possible topical treatment option in the case of second-degree burn wounds.

Vibrio cholerae toxin coregulated pilus provokes inflammatory responses in Coculture model of Caco-2 and peripheral blood mononuclear cells (PBMC) leading to increased colonization.

The aim of this study was to assess the modulatory effect of TcpA in the expression of CEACAM1 adhesin molecule and IL-1, IL-8, and TNF-α pro-inflammatory cytokines in the Coculture model of Caco-2/PBMC (peripheral blood mononuclear cell) that can mimic the intestinal milieu. The TcpA gene from Vibrio cholerae ATCC14035 was cloned in pET-28a and transformed into Escherichia coli Bl-21. The recombinant TcpA-His6 protein was expressed and purified using Ni-column chromatography. The sequencing of transformed plasmid and Western blot analysis of purified protein confirmed the identity of rTcp. The cytotoxicity of different concentrations of recombinant protein for human colon carcinoma cell line (human colorectal adenocarcinoma cell [Caco-2 cell]) was assessed by MTT assay and showed viability of 92%, 82%, and 70%, for 10 µg/mL of TcpA after 24, 48, and 72 h, respectively. Co-cultures of Caco-2 and PBMCs were used to mimic the intestinal milieu and treated with different concentrations of rTcpA (1, 5, 10, and 50 µg/mL). Our data showed about 2.04-, 3.37-, 3.68-, and 42.7-fold increase in CEACAM1 gene expression, respectively, compared with the nontreated Caco-2/PBMC Coculture. Moreover, the expression of IL-1, IL-8, and TNF-α genes was significantly increased up to 15.75-, 7.04-, and 80.95-folds, respectively. In conclusion, V. cholerae TcpA induces statistically significant dose-dependent stimulatory effect on TNF-α, IL-,1, and IL-8 pro-inflammatory cytokines expression. Of these, TNF-α was much more affected which, consequently, elevated the CEACAM1 expression level in IECs. This suggests that TcpA protein is a critical effector as an inducer of increased adhesion potential of V. cholera as well as inflammatory responses of host intestinal tissue.

Recombinant Production of a Novel Fusion Protein: Listeriolysin O Fragment Fused to S1 Subunit of Pertussis Toxin.

Background: Some resources have suggested that genetically inactivated pertussis toxoid (PTs) bear a more protective effect than chemically inactivated products. This study aimed to produce new version of PT, by cloning an inactive pertussis toxin S1 subunit (PTS1) in a fusion form with N-terminal half of the listeriolysin O (LLO) pore-forming toxin. Methods: Deposited pdb structure file of the PT was used to model an extra disulfide bond. Codon-optimized ORF of the PTS1 was used to make recombinant constructs of PTS1 and LLO-PTS1 in the pPSG-IBA35 vector. The recombinant PTS1 and LLO-PTS1 proteins were expressed in BL21 DE3 and SHuffle T7 strains of E. coli and purified by affinity chromatography. Cytotoxic effects of the recombinant proteins were examined in the MCF-7 cell line. Results: The purity of the products proved to be more than 85%, and the efficiency of the disulfide bond formation in SHuffle T7 strain was higher than BL21 DE3 strain. No cytotoxicity of the recombinant proteins was observed in MCF-7 cells. Soluble recombinant PTS1 and LLO-PTS1 proteins were produced in SHuffle T7 strain of E. coli with high efficiency of disulfide bonds formation. Conclusion: The LLO-PTS1 with corrected disulfide bonds was successfully expressed in E. coli SHuffle T7 strain. Due to the safety for human cells, this chimeric molecule can be an option to prevent pertussis disease if its immunostimulatory effects would be confirmed in the future.

Investigating the relationship between extended spectrum ß-lactamase producing Escherichia coli in the environment and food chains with the presence of this infection in people suspected of septicemia: Using the fuzzy set qualitative comparative analysis.

PROPOSE: Among antibiotic resistance cases, resistance to ß-lactam antibiotics is a major concern for the treatment of microbial infections. Furthermore, the prevalence of extended-spectrum ß-lactamases (ESBL) Escherichia coli (E. coli) in environment, food, and human resources of Iran has increased over the past few years. This study aimed to predict the relationship between the prevalence of ESBL E. coli in the environment and the food chains with the presence of this infection in people suspected of septicemia using fuzzy set qualitative comparative analysis model. METHODS: In this analytical cross sectional study samples were collected from the environment (hospital sewage, downstream and upstream urban sewage, and slaughterhouse sewage), food (chicken), and human chains (people suspected of septicemia) in Tehran province, Iran. This study was conducted from September to February 2019 and the prevalence of ESBL E. coli was calculated in each resource. Then, the relationship between the prevalence of ESBL E. coli in the environment and food chains and its prevalence in the human chain was predicted using the fuzzy set qualitative comparative analysis. RESULTS: The results showed the prevalence of ESBL E. coli in those suspected of septicemia in September, October, November, December, January and February was 58.1%, 60%, 33.3%, 100%, 43%, and 57.8%, respectively. Also, the results of the fuzzy set qualitative comparative analysis indicated hospital wastewater and chicken contamination with ESBL E. coli were the main causes of contamination with ESBL E. coli in people suspected of septicemia. CONCLUSIONS: According to the results of this study, if there is a contamination of hospital wastewater and chickens in an area, it can be claimed that people suspected of septicemia are infected with ESBL E. coli, and the percentage of this contamination can be high. On the other hand, controlling ESBL E. coli in hospital wastewater (environmental chain) and chickens (food chain) can prevent contamination in people with suspected septicemia.

Bactericidal impact of Ag, ZnO and mixed AgZnO colloidal nanoparticles on H37Rv Mycobacterium tuberculosis phagocytized by THP-1 cell lines.

The purpose of this research project was to infection of human macrophages (THP-1) cell lines by H37Rv strain of Mycobacterium tuberculosis (H37RvMTB) and find out the ratio/dilution of mixture silver (Ag NPs) and zinc oxide nanoparticles (ZnO NPs) whose ability to eliminate phagocytized bacteria compared to rifampicin. The colloidal Ag NPs and ZnO NPs were synthesized and their characteristics were evaluated. The THP-1 cell lines were infected with different concentration of H37RvMTB. Next, the infected cells were treated with different ratios/dilutions of Ag NPs, ZnO NPs and rifampicin. The THP-1 were lysed and were cultured in Lowenstein-Jensen agar medium, for eight weeks. The TEM and AFM images of NPs and H37RvMTB were supplied. It is observed that Ag NPs, 2Ag:8ZnO and 8Ag:2ZnO did not have any anti-tubercular effects on phagocytized H37RvMTB. Conversely, ZnO NPs somehow eliminated 18.7 × 104 CFU ml-1 of H37RvMTB in concentration of ∼ 0.468 ppm. To compare with 40 ppm of rifampicin, ∼ 0.663 ppm of 5Ag:5ZnO had the ability to kill of H37RvMTB, too. Based on previous research, ZnO NPs had strong anti-tubercular impact against H37RvMTB to in-vitro condition, but it was toxic in concentration of ∼ 0.468 ppm to both of THP-1 and normal lung (MRC-5) cell lines. It also seems that 5Ag:5ZnO is justified because in concentration of ∼ 0.663 ppm of 5Ag:5ZnO, phagocytized H37RvMTB into the THP-1 had died without any toxicity effects against THP-1 and also MRC-5 cell lines. It is obvious that the mixture of colloidal silver and zinc oxide NPs with ratio of 5Ag:5ZnO would be trustworthy options as anti-tubercular nano-drugs in future researches.

Dose-Dependent Effects of Common Antibiotics Used to Treat Staphylococcus aureus on Biofilm Formation.

BACKGROUND & OBJECTIVE: Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), represent serious nosocomial and community infections. Biofilm formation as an important virulence factor may be affected by sub-inhibitory levels of antibiotics. Few studies examined the effects of all therapeutic antimicrobial agents on clinical S.aureus. The current study aimed at observing the inducing and reducing effects of antibiotics, commonly used to treat staphylococcal infections on the production of staphylococcal biofilm. METHODS: Four MRSA (1ATCC and 3 clinical) and 1 methicillin-susceptible Staphylococcus aureus (MSSA) strains with biofilm forming ability, evaluated by the Congo red agar (CRA) plate test, were employed. Biofilm formation was measured by crystal violet microtiter plate assay. Cefazolin, rifampicin, vancomycin, oxacillin, clindamycin, cotrimoxazole, minocycline, linezolid, azithromycin, and clarithromycin were added to wells ranging from 0.06to 128 µg/mL (1× to 1/1024 MIC dependent on the MIC value of each strain). RESULTS: The current study showed that azithromycin and vancomycin had a significant inducing effect on biofilm formation. In contrast, linezolid, cefazolin, and clarithromycin, and in the second place, clindamycin and minocycline could inhibit the level of biofilm production in the sub-minimal inhibitory concentrations. CONCLUSION: The findings demonstrated that the biofilm formation as an important virulence factor may be affected by the subinhibitory levels of antibiotics.

Resistance-Gene Cassettes Associated With Salmonella enterica Genotypes.

BACKGROUND: The epidemiology of salmonellosis is complex because of the diversity and different serotypes of Salmonella enterica (S. enterica) that occur in different reservoirs and geographic incidences. OBJECTIVES: To determine the genotype distribution and resistance-gene content of 2 classes of integron among S. enterica isolates. METHODS: Thirty-six S. enterica species were isolated and tested for their serological distribution and the resistance-gene contents of 2 classes of integron, as well as for their genetic diversity, using the pulsed-field gel electrophoresis (PFGE) genotyping method. RESULTS: Serogroups E (36.1%) and D (30.5%) were dominant among the isolates. All of the isolates in serogroup D belonged to the serovar enteritidis. The aadA1 gene was found within all resistance-gene cassettes. We observed 4 common and 26 single pulsotypes among the isolates, which indicated a high degree of genetic diversity among the isolates. Using the PulseNet International standard protocol, it was found that these isolates were different from those reported previously in Iran. CONCLUSIONS: The presence of a few common and new pulsotypes among the isolates suggests the emergence and spread of new clones of S. enterica in Iran.

A single point mutation within the coding sequence of cholera toxin B subunit will increase its expression yield.

BACKGROUND: Cholera toxin B subunit (CTB) has been extensively considered as an immunogenic and adjuvant protein, but its yield of expression is not satisfactory in many studies. The aim of this study was to compare the expression of native and mutant recombinant CTB (rCTB) in pQE vector. METHODS: ctxB fragment from Vibrio cholerae O1 ATCC14035 containing the substitution of mutant ctxB for amino acid S128T was amplified by PCR and cloned in pGETM-T easy vector. It was then transformed to E. coli Top 10F' and cultured on LB agar plate containing ampicillin. Sequence analysis confirmed the mature ctxB gene sequence and the mutant one in both constructs which were further subcloned to pQE-30 vector. Both constructs were subsequently transformed to E. coli M15 (pREP4) for expression of mature and mutant rCTB. RESULTS: SDS-PAGE analysis showed the maximum expression of rCTB in both systems at 5 hours after induction and Western-blot analysis confirmed the presence of rCTB in blotting membranes. The expression of mutant rCTB was much higher than mature rCTB, which may be the result of serine-to-threonine substitution at position 128 of mature rCTB amino acid sequence created by PCR mutagenesis. The mutant rCTB retained pentameric stability and its ability to bind to anti- cholera toxin IgG antibodies. CONCLUSION: Point mutation in ctxB sequence resulted in over-expression of rCTB, probably due to the increase of solubility of produced rCTB. Consequently, this expression system can be used to produce rCTB in high yield.

The hows and whys of constructing a native recombinant cholera vaccine.

Emergence of different ctxB genotypes within virulent Vibrio cholerae populations accentuates the need to develop a vaccine that has the potential to protect against all cholera toxin genotypes. Oral administration of rCTB-alone and in combination with 2 dominant domestic killed whole cells of V. cholerae (O1 Ogawa El Tor and O1 Inaba El Tor) plus one standard V. cholerae (O1 Ogawa classic ATCC 14035)-has shown satisfactory protection as a potent vaccine candidate against toxigenic V. cholerae.

Contribution of AcrAB efflux pump to ciprofloxacin resistance in Klebsiella pneumoniae isolated from burn patients.

Resistance to fluoroquinolones has been recently increased among bacterial strains isolated from outpatients. Multidrug-resistant K. pneumoniae is one of the major organisms isolated from burn patients and the AcrAB efflux pump is the principal pump contributing to the intrinsic resistance in K. pneumoniae against multiple antimicrobial agents including ciprofloxacin and other fluoroquinolones. Fifty-two K. pneumoniae isolated from burn patients in Shahid Motahari hospital and confirmed by conventional biochemical tests. Antimicrobial susceptibility testing was done according to CLSI 2011 guidelines, to determine the antimicrobial resistance pattern of isolates. AcrA gene was detected among ciprofloxacin-resistant isolates by PCR assay. MICs to ciprofloxacin were measured with and without carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Forty out of the 52 K. pneumoniae isolated from burn patients in Shahid Motahari hospital were resistant to ciprofloxacin according to breakpoint of CLSI guideline. PCR assay for acrA gene demonstrated that all ciprofloxacin-resistant isolates harbored acrA gene coding the membrane fusion protein AcrA and is a part of AcrAB efflux system. Among these isolates, 19 strains (47.5%) showed 2 to 32 fold reduction in MICs after using CCCP as an efflux pump inhibitor. The other 21 strains (52.5%) showed no disparity in MICs before and after using CCCP. In conclusion, the AcrAB efflux system is one of the principal mechanisms contribute in ciprofloxacin resistance among K. pneumoniae isolates but there are some other mechanisms interfere with ciprofloxacin resistance such as mutation in target proteins of DNA gyrase of topoisomerase IV enzymes.

Biological activity of recombinant accessory cholerae enterotoxin (ace) on rabbit ileal loops and antibacterial assay.

OBJECTIVE: Vibrio cholerae (V. cholerae) causes a potentially lethal disease named cholera. The cholera enterotoxin (CT) is a major virulence factor of V. cholerae. In addition to CT, V. cholerae produces other putative toxins, such as the zonula occludens toxin (Zot) and accessory cholera enterotoxin (Ace). The ace gene is the third gene of the V. cholerae virulence cassette. The Ace toxin alters ion transport, causes fluid accumulation in ligated rabbit ileal loops, and is a cause of mild diarrhea. The aim of this study is the cloning and overexpression of the ace gene into Escherichia coli (E. coli) and determination of some characteristics of the recombinant Ace protein. MATERIALS AND METHODS: In this experimental study, the ace gene was amplified from V. cholerae strain 62013, then cloned in a pET28a expression vector and transformed into an E. coli (DH5 α) host strain. Subsequently, the recombinant vector was retransformed into E. coli BL21 for expression, induced by isopropythio-ß-D-galctoside (IPTG) at a different concentration, and examined by SDS-PAGE and Western blot. A rabbit ileal loop experiment was conducted. Antibacterial activity of the Ace protein was assessed for E. coli, Stapylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa). RESULTS: The recombinant Ace protein with a molecular weight of 18 kDa (dimeric form) was expressed in E. coli BL21. The Ace protein showed poor staining with Coomassie blue stain, but stained efficiently with silver stain. Western blot analysis showed that the recombinant Ace protein reacted with rabbit anti-V. cholerae polyclonal antibody. The Ace protein had antibacterial activity at a concentration of ≥200 µg/ml and caused significant fluid accumulation in the ligated rabbit ileal loop test. CONCLUSION: This study described an E. coli cloning and expression system (E. coli BL21- pET-28a-ace) for the Ace protein of V. cholerae. We confirmed the antibacterial properties and enterotoxin activity of the resultant recombinant Ace protein.