The Role of Helicobacter pylori Proinflammatory Outer Membrane Protein and Propolis in Immunomodulation on U937 Macrophage Cell Model

Background

Regarding the important role of proinflammatory outer membrane protein (OipA) in the pathogenesis of Helicobacter pylori infection and immunomodulatory activity of propolis, we aimed to evaluate the immunogenicity effect of a purified recombinant OipA protein and propolis in the induction of two cytokines, interferon-gamma (IFN-γ) and interleukin-4 (IL-4), in a macrophage cell model.

Materials and Methods

The recombinant protein used in the present study corresponding to the oipA expressing a 34-35 kDa protein. OipA protein was purified by Ni-NTA affinity chromatography. The purified OipA protein (2.5- 40 μg /mL) and the propolis ethanolic extract (5-40 μg/mL) were incubated with phorbol 12-myristate 13-acetate-treated human myelomonocytic cell line U937 cells. IL-4 and IFN-γ levels were measured after 48 hours of incubation using enzyme-linked immunosorbent assay.

Results

The amounts of IL-4 and IFN-γ were significantly increased. The optimum concentration of OipA for the secretion of IL-4 was 5 μg/ml (P<0.0001). At higher concentrations, the amount of IL-4 diminished until suppression at 40 μg/mL. The optimum concentration of propolis, resulting in the most significant increased secretion of both IL-4 and IFN-γ was 40 μg/mL (P=0.0001 and P=0.0004).

Conclusion

We found that an OipA concentration of 10 μg/mL was more effective for IFN-γ production; however, it was not effective for the high production of IL-4. Therefore, it is postulated that the OipA could mainly induce a Th1 response through the production of IFN-γ. We also observed propolis's capability to induce IFN-γ production; however, the effective concentration for this was the same as for IL-4. Therefore, as an adjuvant, proper concentration of propolis is required for OipA to give the optimum response.

Evaluation of Helicobacter pylori OipA protein as a vaccine candidate and propolis as an adjuvant in C57BL/6 mice

OBJECTIVES

Outer inflammatory protein A (OipA) is an essential adhesin of Helicobacter pylori. We aimed to evaluate the effects of a recombinant OipA in the induction of crucial cytokines as a vaccine candidate and propolis as an adjuvant in C57BL/6 mice.

MATERIALS AND METHODS

C57BL/6 mice were divided into nine groups according to the disposition of antigen and adjuvant and route of administration: subcutaneous (sc) or gavage. The administrated recombinant purified OipA and propolis concentrations were 10 μg/ml and 40 μg/ml, respectively. After vaccination, we measured expression levels of IFN-γ and IL-4 cytokine genes in the spleen cells of mice by real-time PCR.

RESULTS

All results were contrasted with the negative sample. By sc injection, the expression of INF-γ was increased 3.5 and 2.9-fold for OipA and OipA plus propolis, respectively. By gavage 4.4 and 11-fold increase was found for OipA and OipA plus propolis, respectively. The administration of propolis by gavage showed more increase than Sc injection concerning the production of INF-γ. The 11-fold increase for injection of OipA plus propolis by gavage was comparable OipA plus Freund's adjuvant injected subcutaneously. This result suggested an excellent immunological response toward OipA concerning the production of INF-γ in mice. In all cases there were no notable IL-4 production increases.

CONCLUSION

The results confirm the efficiency of OipA in induction of IFN-γ production, and thereby the cellular immune response. Propolis could be a suitable adjuvant.

A Comparative Taxonomic Profile of Microbial Polyethylene and Hydrocarbon-Degrading Communities in Diverse Environments

Background

Polyethylene (PE) is one of the most abundant plastic wastes which accumulates in marine and terrestrial environments. As microbial degradation has been a promising approach for the bioremediation of polluted environments, identification of the microbial community profile where these pollutants accumulate, has recently been in focus.

Objective

We have investigated the taxonomic and functional characteristics of polyethylene- degrading microorganisms in a plastic waste recycling site in Tehran, Iran.

Materials and Methods

We have analyzed and compared a 16S rRNA dataset from this study with 15 datasets from 4 diverse plastic and oil polluted habitats to identify and evaluate bacterial communities involved in bioremediation.

Results

Our findings reveal that Proteobacteria, Actinobacteria, Acidobacteria and Cloroflexi were the dominant phyla and Actinobacteria, Alphaproteobacteria, Gammaproteobacteria and Acidimicrobia were dominant classes in these samples. The most dominant Kegg Orthology associated with PE bioremediation in these samples are related to peroxidases, alcohol dehydrogenases, monooxygenases and dioxygenases.

Conclusions

Long-term presence of contaminants in soil could lead to changes in bacterial phyla abundance, resulting in metabolic adaptations to optimize biological activity and waste management in a diverse group of bacteria.

Considerable increase in Poly(3-hydroxybutyrate) production via phbC gene overexpression in Ralstonia eutropha PTCC 1615

Introduction: Poly(3-hydroxybutyrate) (PHB) is a well-known biodegradable polymer produced by some microorganisms and can be a suitable alternative for petrochemical plastics. PHB synthase encoded by phb C gene is the main enzyme in PHB biosynthesis pathway in Ralstonia eutropha. The aim of current study was the transformation of R. eutropha PTCC 1615 with its own phb C gene and evaluation of the overexpression effect on PHB accumulation.

Methods: DNA fragment including phbC gene and its promoter and terminator regions, was isolated from R. eutropha PTCC 1615, inserted into pET28a(+) vector, and transferred to the competent bacteria using calcium chloride and heat shock method. The effect of the cloned gene expression on PHB production was investigated with absorption of crotonic acid produced through PHB dehydration. Statistical analyses were carried out by SPSS software.

Results: PHB content of cells of the engineered strain was 1.4 times more than that of the native bacteria. This significant difference can be an important finding for improvement of biopolymer production.

Conclusion: Overexpression of phb C, the critical gene in PHB biosynthesis pathway, in R. eutropha PTCC 1615 had considerable effect on PHB accumulation.

Ecological role of Acinetobacter calcoaceticus GSN3 in natural biofilm formation and its advantages in bioremediation

This study assessed the role of a new Acinetobacter calcoaceticus strain, GSN3, with biofilm-forming and phenol-degrading abilities. Three biofilm reactors were spiked with activated sludge (R1), green fluorescent plasmid (GFP) tagged GSN3 (R2), and their combination (R3). More than 99% phenol removal was achieved during four weeks in R3 while this efficiency was reached after two and four further operational weeks in R2 and R1, respectively. Confocal scanning electron microscopy revealed that GSN3-gfp strains appeared mostly in the deeper layers of the biofilm in R3. After four weeks, almost 7.07 × 10⁷ more attached sludge cells were counted per carrier in R3 in comparison to R1. Additionally, the higher numbers of GSN3-gfp in R2 were unable to increase the efficiency as much as measured in R3. The presence of GSN3-gfp in R3 conveyed advantages, including enhancement of cell immobilization, population diversity, metabolic cooperation and ultimately treatment efficiency.

Highly efficient phenol degradation in a batch moving bed biofilm reactor: benefiting from biofilm-enhancing bacteria

In this study, the efficiency improvement of three moving bed biofilm reactors (MBBRs) was investigated by inoculation of activated sludge cells (R1), mixed culture of eight strong phenol-degrading bacteria consisted of Pseudomonas spp. and Acinetobacter spp. (R2) and the combination of both (R3). Biofilm formation ability of eight bacteria was assessed initially using different methods and media. Maximum degradation of phenol, COD, biomass growth and also changes in organic loading shock were used as parameters to measure the performance of reactors. According to the results, all eight strains were determined as enhanced biofilm forming bacteria (EBFB). Under optimum operating conditions, more than 90% of initial COD load of 2795 mg L^-1 was reduced at 24 HRT in R3 while this reduction efficiency was observed in concentrations of 1290 mg L^-1 and 1935 mg L^-1, in R1 and R2, respectively. When encountering phenol loading shock-twice greater than optimum amount-R1, R2 and R3 managed to return to the steady-state condition within 32, 24 and 18 days, respectively. SEM microscopy and biomass growth measurements confirmed the contribution of more cells to biofilm formation in R3 followed by R2. Additionally, established biofilm in R3 was more resistant to phenol loading shock which can be attributed to the enhancer role of EBFB strains in this reactor. It has been demonstrated that the bacteria with both biofilm-forming and contaminant-degrading abilities are not only able to promote the immobilization of other favorable activated sludge cells in biofilm structure, but also cooperate in contaminant degradation which all consequently lead to improvement of treatment efficiency.

Characterization of gyrA and parC mutations in ciprofloxacin-resistant Pseudomonas aeruginosa isolates from Tehran hospitals in Iran

BACKGROUND AND OBJECTIVES

Pseudomonas aeruginosa, a major cause of several infectious diseases, has become a hazardous resistant pathogen. One of the factors contributing to quinolone resistance in P. aeruginosa is mutations occurring in gyrA and parC genes encoding the A subunits of type II and IV topoisomerases, respectively, in quinolone resistance determining regions (QRDR) of the bacterial chromosome.

MATERIALS AND METHODS

Thirty seven isolates from patients with burn wounds and 20 isolates from blood, urine and sputum specimen were collected. Minimum Inhibitory Concentrations (MICs) of ciprofloxacin were determined by agar diffusion assay. Subsequently, QRDRs regions of gyrA and parC were amplified from resistant isolates and were assessed for mutations involved in ciprofloxacin resistance after sequencing.

RESULTS

Nine isolates with MIC≥8 μg/ml had a mutation in gyrA (Thr83→Ile). Amongst these, seven isolates also had a mutation in parC (Ser87→ Leu or Trp) indicating that the prevalent mutation in gyrA is Thr83Ile and Ser87Leu/Trp in parC. No single parC mutation was observed.

CONCLUSION

It seems that mutations in gyrA are concomitant with mutations in parC which might lead to high-level ciprofloxacin resistance in P. aeruginosa isolates from patients with burn wounds and urinary tract infections.

The role of probiotic Lactobacillus acidophilus ATCC 4356 bacteriocin on effect of HBsu on planktonic cells and biofilm formation of Bacillus subtilis

Bacillus subtilis is a Gram positive, aerobic and motile bacterium. Biofilm formation is an important feature of this bacterium which confers resistance to antimicrobial agents. The use of new antimicrobial reagents which eliminate biofilms are important and necessary. In this study, the effect of secondary metabolites (bacteriocin) from Lactobacillus acidophilus ATCC 4356 on Bacillus subtilis BM19 in the presence and absence of HBsu which is involved in the growth of planktonic cells and biofilm formation, is reported. HBsu nucleoprotein plays several roles in different processes of Bacillus subtilis cells such as replication, transcription, cell division, recombination and repair. In this study, for the first time, the effect of HBsu on biofilm formation is presented.

RESULTS

In the absence of HBsu, purified bacteriocin from L. acidophilus ATCC 4356 was more effective in inhibiting growth of B. subtilis BM19 planktonic cells as well as biofilm formation. The presence of HBsu on the other hand led to increased biofilm formation.

Screening of Alginate Lyase-Producing Bacteria and Optimization of Media Compositions for Extracellular Alginate Lyase Production

Background:

Alginate is a linear polysaccharide consisting of guluronate (polyG) and mannuronate (polyM) subunits.

Methods:

In the initial screening of alginate-degrading bacteria from soil, 10 isolates were able to grow on minimal medium containing alginate. The optimization of cell growth and alginate lyase (algL) production was carried out by the addition of 0.8% alginate and 0.2-0.3 M NaCl to the culture medium. Of 10 isolates, one was selected based on its fast growth rate on minimal 9 medium containing 0.4% sodium alginate. The selected bacterium, identified based on morphological and biochemical characteristics, as well as 16S rDNA sequence data, was confirmed to be an isolate belonging to the genus Bacillus and designated as Bacillus sp. TAG8.

Results:

The results showed the ability of Bacillus sp. TAG8 in utilizing alginate as a sole carbon source. Bacillus sp. TAG8 growth and algL production were augmented with an increase in sodium alginate concentration and also by the addition of 0.2-0.3 M NaCl. Molecular analysis of TAG8 algL gene showed 99% sequence identity with algL of Pseudomonasaeruginosa PAO1. The algL produced by Bacillus sp. TAG8 cleaved both polyM and polyG blocks in alginate molecule, as well as acetylated alginate residues, confirming the bifunctionality of the isolated lyase.

Conclusion:

The identification of novel algL genes from microbial communities constitutes a new approach for exploring lyases with specific activity against bacterial alginates and may thus contribute to the eradication of persistent biofilms from clinical samples.

Ex situ study of Enterococcus faecalis survival in the recreational waters of the southern coast of the Caspian Sea

BACKGROUND AND OBJECTIVES

The US Environmental Protection Agency has suggested faecal enterococci as the primary bacterial indicators. Of more importance is their direct correlation with swimmer-associated gastroenteritis in recreation water quality monitoring. In contrast to other seawater bodies with 3.5% salinity, the recreational waters in the southern coast of the Caspian Sea possess its own salinity (about 1% w/v) and thus require further investigations to determine the capacity of Enterococcus faecalis as the sole primary microbial index in this unique aquatic environment.

MATERIALS AND METHODS

The survey of the presence and survival of E. faecalis as a microbial index in the recreational waters of the southern Caspian Sea was carried out using a microcosm as an experimental model. The concentration of E. faecalis cells in samples of seawater were estimated by a standard membrane filtration method using m-Enterococcus agar as the selective culture medium. As the current standard culture-based methods are not reliable enough for the detection of non-growing, damaged and under-tension bacteria, PCR was used to identify the possible VBNC form of the bacterium after disappearance of the culturable cells.

RESULTS AND CONCLUSION

A continuous decline in the number of culturable E. faecalis cells resulted in apparent elimination of the bacteria from seawater in a defined period. Detection of intact DNA was possible in the following 60 days. The salinity of about 1% and the self-purification properties of the Caspian Sea make the conditions feasible for the use of this microorganism as a measure of water quality throughout the region. The results confirmed the presence of damaged bacterial cells, namely VBNC forms, indicating the necessity of examining of the sea water samples by using molecular approaches or repair procedures.

Study of antagonistic effects of Lactobacillus strains as probiotics on multi drug resistant (MDR) bacteria isolated from urinary tract infections (UTIs)

OBJECTIVE(S)

Urinary tract infection (UTI) caused by bacteria is one of the most frequent infections in human population. Inappropriate use of antibiotics, often leads to appearance of drug resistance in bacteria. However, use of probiotic bacteria has been suggested as a partial replacement. This study was aimed to assess the antagonistic effects of Lactobacillus standard strains against bacteria isolated from UTI infections.

MATERIALS AND METHODS

Among 600 samples; those with ≥10,000 cfu/ml were selected as UTI positive samples. Enterococcus sp., Klebsiella pneumoniae, Enterobacter sp., and Escherichia coli were found the most prevalent UTI causative agents. All isolates were screened for multi drug resistance and subjected to the antimicrobial effects of three Lactobacillus strains by using microplate technique and the MICs amounts were determined. In order to verify the origin of antibiotic resistance of isolates, plasmid curing using ethidium bromide and acridine orange was carried out.

RESULTS

No antagonistic activity in Lactobacilli suspension was detected against test on Enterococcus and Enterobacter strains and K. pneumoniae, which were resistant to most antibiotics. However, an inhibitory effect was observed for E. coli which were resistant to 8-9 antibiotics. In addition, L. casei was determined to be the most effective probiotic. RESULTS from replica plating suggested one of the plasmids could be related to the gene responsible for ampicillin resistance.

CONCLUSION

Treatment of E. coli with probiotic suspension was not effective on inhibition of the plasmid carrying hypothetical ampicillin resistant gene. Moreover, the plasmid profiles obtained from probiotic-treated isolates were identical to untreated isolates.

Assessment of Biofilm Formation and Resistance to Imipenem and Ciprofloxacin among Clinical Isolates of Acinetobacter baumannii in Tehran

Background:

Biofilms are communities of bacteria attached to the surfaces in an extracellular polymeric matrix which are associated with many chronic infections in humans. Acinetobacter spp. are emerging as a major cause of nosocomial infections and Acinetobacterbaumannii is the predominant species associated with this kind of infections.

Objectives:

In the present study, the potential of biofilm formation of clinical isolates, A. baumannii, was assessed by using crystal violet method. Furthermore, susceptibility pattern of these strains to ciprofloxacin and imipenem was determined.

Methods and Materials:

Biofilm formation by 75 A. baumannii isolates was evaluated by using microtiter plate and tube methods and crystal violet staining. Tube method was carried out under static and shaking conditions. Then, the susceptibility of isolates to ciprofloxacin and imipenem was determined.

Results:

Results showed that in tube method under shaking, 22% of clinical isolates were strong biofilm producers while 23% of them were not able to form biofilms. In this experiment, 18% and 42% of isolates were considered as moderate and weak biofilm-forming strains, respectively. In microtiter plate tests, 18% of strains were strong-biofilm producers and 25% of them were notable biofilm producers. In this assessment, 10% and 47% were considered as moderate and weak biofilm-forming isolates, respectively. The susceptibility tests, using microdilution method, confirmed that 92% of these isolates were resistant and 6.6% were susceptible to ciprofloxacin, although these results for imipenem were 68% and 24%, respectively.

Conclusions:

It can be concluded that most of A. baumannii isolates can form biofilm in microtiter plate and tube. The results also verified that most of these isolates were resistant to ciprofloxacin and imipenem.

Cane molasses as a source of precursors in the bioproduction of tryptophan by Bacillus subtilis

BACKGROUND AND OBJECTIVES

The essential amino acid L-tryptophan can be produced by a condensation reaction between indole and L-serine, catalyzed by B. subtilis with tryptophan synthase activity. Application of the tryptophan is widespread in the biotechnology domain and is sometimes added to feed products as a food fortifier.

MATERIALS AND METHODS

The optimum concentration of the Iranian cane molasses was determined by measuring the amount of biomass after growth in 1 to 30 g/mL of molasses. The maximum amount of biomass was obtained in 10 g/mL molasses. Chromatographic methods, TLC and HPLC, were used to assay the amount of tryptophan produced in the presence of precursors of tryptophan production (indole and serine) and/or molasses.

RESULTS

Our results indicate the importance of the Iranian cane molasses not only as carbon source, but also as a source of precursors for tryptophan production.

CONCLUSION

This report evaluates the potential of cane molasses as an economical source for tryptophan production by B. subtilis, hence eliminating the requirement for additional serine and indole as precursors.

Screening of SDS-degrading bacteria from car wash wastewater and study of the alkylsulfatase enzyme activity

BACKGROUND AND OBJECTIVES

Sodium dodecyl sulfate (SDS) is one of the main surfactant components in detergents and cosmetics, used in high amounts as a detergent in products such as shampoos, car wash soap and toothpaste. Therefore, its bioremediation by suitable microorganisms is important. Alkylsulfatase is an enzyme that hydrolyses sulfate -ester bonds to give inorganic sulfate and alcohol. The purpose of this study was to isolate SDS-degrading bacteria from Tehran city car wash wastewater, study bacterial alkylsulfatase enzyme activity and identify the alkylsulfatase enzyme coding gene.

MATERIALS AND METHODS

Screening of SDS-degrading bacteria was carried out on basal salt medium containing SDS as the sole source of carbon. Amount of SDS degraded was assayed by methylene blue active substance (MBAS).

RESULTS AND CONCLUSION

Identification of the sdsA gene was carried by PCR and subsequent sequencing of the 16S rDNA gene and biochemical tests identified Pseudomonas aeruginosa. This bacterium is able to degrade 84% of SDS after four days incubation. Bacteria isolated from car wash wastewater were shown to carry the sdsA gene (670bp) and the alkylsulfatase enzyme specific activity expressed from this gene was determined to be 24.3 unit/mg. The results presented in this research indicate that Pseudomonas aeruginosa is a suitable candidate for SDS biodegradation.

Degradation of a textile reactive azo dye by a combined biological-photocatalytic process: Candida tropicalis Jks2 -Tio2/Uv

In the present study, the decolorization and degradation of Reactive Black 5 (RB5) azo dye was investigated by biological, photocatalytic (UV/TiO₂) and combined processes. Application of Candida tropicalis JKS2 in treatment of the synthetic medium containing RB5 indicated complete decolorization of the dye with 200 mg/L in less than 24 h. Degradation of the aromatic rings, resulting from the destruction of the dye, did not occur during the biological treatment. Mineralization of 50 mg/L RB5 solution was obtained after 80 min by photocatalytic process (in presence of 0.2 g/L TiO₂). COD (chemical oxygen demand) was not detectable after complete decolorization of 50 mg/L RB5 solution. However, photocatalytic process was not effective in the removal of the dye at high concentrations (≥200 mg/L). With 200 mg/L concentration, 74.9% of decolorization was achieved after 4 h illumination under photocatalytic process and the absorbance peak in UV region (attributed to aromatic rings) was not completely removed. A two-step treatment process, namely, biological treatment by yeast followed by photocatalytic degradation, was also assessed. In the combined process (with 200 mg/L RB5), absorbance peak in UV region significantly disappeared after 2 h illumination and about 60% COD removal was achieved in the biological step. It is suggested that the combined process is more effective than the biological and photocatalytic treatments in the remediation of aromatic rings.

Cloning the hbs gene from Bacillus subtilis and expression of the HBsu protein in Escherichia coli

BACKGROUND AND OBJECTIVES

Bacillus subtilis HBsu is a 10 kD heat-stable protein shown to be involved in binding to DNA and is encoded by the hbs gene. Large-scale production for biochemical analysis is achieved through cloning and expression of the recombinant protein.

MATERIALS AND METHODS

This gene was amplified from B. subtilis ATCC 6633 using PCR and cloned into pET28a (+) expression vector. The construct was used to transform Escherichia coli BL21 (DE3). The expression of the protein was induced by the addition of 1mM IPTG. To confirm the expression of the cloned gene, SDS-PAGE was carried out and production of an approximately 11 KD recombinant tagged protein was confirmed for the cloned hbs gene.

RESULTS AND CONCLUSION

The identity of the recombinant HBsu was verified and characterized by SDS-PAGE which can then be utilized for further applications.

Non-radioactive labeled probe preparation for hbs gene detection

Among some Bacillus species, a protein highly homologous to HU, classified HB and coded by hbs gene. According to the recent studies, the sequence of hbs gene just in one strain of Bacillus subtilis exists in gene bank (ATCC 23857). In this study, DNA from Bacillus subtilis ATCC 6633 was extracted and investigated by PCR. The PCR product was sequenced and shown to differ in just one nucleotide from B. subtilis ATCC 23857. Hence, it was chosen as reference and for the first time, used for non-radioactive labeled probe preparation. The PCR product in Bacillus subtilis with ATCC 6633 was labeled using non-radioactive DIG-labeled nucleotides and conditions of probe preparation and hybridization were optimized and checked it by Southern blotting.

Bioprocessing of seleno-oxyanions and tellurite in a novel Bacillus sp. strain STG-83: a solution to removal of toxic oxyanions in presence of nitrate

Bioremediation of toxic nonmetal and metalloid oxyanions is of great interest. In this study, among 148 bacterial isolates from two types of polluted water, strain STG-83 showed maximum oxyanion reduction and resistance ability. Sequencing of the 16S rDNA gene of STG-83 showed that the strain is closely related to Bacillus pumilus and morphological and biochemical tests confirmed the result. The strain was nitrate negative, but it could reduce half of tellurite in solution containing 1-mM concentration and completely reduced selenite and selenate in solutions containing 1-mM concentrations. Both reduction to elemental form and volatilization occurred in case of all oxyanions tested, according to hydride generation atomic absorption spectroscopy and proton induced X-ray emission analytical methods. The strain was able to tolerate remarkably high concentrations of selenite (640 mM), selenate (320 mM), and tellurite (1250 microM); and tolerance to tellurite increased in presence of selenite and selenate. Biochemical tests and zymogram of extracted culture solutions on gel electrophoresis showed that the strain was nitrate negative and therefore nitrate did not interfere with reduction of other oxyanions. Thus, the strain opens up good opportunities for the bioremediation of polluted waters in natural environment, since nitrate usually inhibits or decelerates reduction of the mentioned toxic oxyanions.

A study of varicella zoster virus glycoprotein C regulatory region response to viral activators in vitro

A study was conducted to analyze the response of varicella zoster virus (VZV) glycoprotein C gene (ORF14) regulatory sequences downstream as well as upstream of the transcription site to VZV transactivators, IE4 and IE62 and p29, the single-stranded DNA binding protein, in vitro by transiently transfecting a permissive human melanoma cell line (Mewo). This glycoprotein has been shown to be an important factor in VZV pathogenesis and therefore the regulation of its expression has been of much interest. In this study, the promoter region of gC as well as another VZV glycoprotein, gI (as a positive control), was amplified and cloned into a promoter less plasmid expressing the luciferase gene as a reporter. The activities of the regulatory regions from both glycoproteins were assessed by quantifying the luciferase activity. The results show that the luciferase assay is a powerful means of measuring promoter activity; nevertheless, the promoter region and cognate downstream and upstream sequences of the true late gC gene were not responsive to these viral proteins, indicating that other viral/cellular factors and/or viral replication could be involved in gC synthesis during the VZV infection cycle.

Pulsed field gel electrophoresis & plasmid profile of Pseudomonas aeruginosa at two hospitals in Tehran, Iran

BACKGROUND & OBJECTIVE

Pseudomonas aeruginosa is a common cause of nosocomial infections and exhibits innate resistance to a wide range of antibiotics. This study was undertaken to determine the resistance patterns of P. aeruginosa isolates recovered from patients at two hospitals in Tehran, to investigate the presence of plasmids and to genetically characterize them by pulsed field gel electrophoresis (PFGE).

METHODS

The susceptibility of 104 isolates of P. aeruginosa to 13 different antibiotics was determined by agar disk diffusion method. The alkaline lysis method was used for plasmid extraction. PFGE technique was optimized for DNA fingerprinting of isolates.

RESULTS

The isolates showed resistance to 13 different antibiotics ceftizoxime (99%), lomefloxacin (94.3%), ceftazidime (59.6%), ticarcillin (50%), ceftriaxone (44.3%), cefoperazone (37.5%), tobramycin (34.6%), piperacillin and gentamicin (33.7%), carbenicillin (25%), amikacin (22%), ciprofloxacin (15.4%) and imipenem (2.9%). Plasmids were detected in 31 isolates (29.8%) that produced 15 different patterns. In total, 84 DNA banding patterns were detected by PFGE. The dominant PFGE type, Pattern A with 14 isolates was found at both hospitals. The remaining isolates were grouped in B, C, D and PF1-PF80. The majority of isolates with the identical plasmid profiles and resistance patterns produced closely related DNA fingerprints by PFGE.

INTERPRETATION & CONCLUSION

Isolates in pattern A were distributed widely at both hospitals and the environment. Absence of plasmids in majority of isolates indicated low typeability and discriminatory power of this technique.

Genetic characterization of high-level gentamicin-resistant strains of Enterococcus faecalis in Iran

The prevalence of resistance to high levels of gentamicin among 182 isolates of Enterococcus faecalis from 2 Iranian hospitals was 42%. Gentamicin resistance was associated with conjugative plasmids (>70 kb) in most strains. Fingerprinting using EcoRI and HindIII showed genetic variation among these plasmids and gave evidence of nosocomial outbreaks and persistence of infection in different wards of the study hospitals, as well as transfer of plasmids between genetically diverse isolates. Using EcoRI, hospital-based specific plasmid fingerprints were detected for the isolates that had previously proved to be unrelated by multilocus enzyme electrophoresis, suggesting the persistence of related plasmids at each hospital, though minor changes in these related plasmids could be detected with HindIII.

Multidrug-resistant strains of Mycobacterium tuberculosis isolated from patients in Tehran belong to a genetically distinct cluster

Restriction fragment length polymorphism (RFLP) analysis was used to study the molecular epidemiology of tuberculosis (TB) in certain areas of Tehran. 120 isolates of Mycobacterium tuberculosis, including drug-resistant strains (n = 23), were analysed using polymorphic GC-rich sequence (PGRS) and IS6110 probes. There was considerable diversity among the strains cultured from patients from certain areas. The results of RFLP showed that multidrug resistant (MDR) isolates of M. tuberculosis in Tehran belong to a group of strains with low copies of IS6110 and PGRS. The degree of clustering was higher for the drug-resistant strains than for the susceptible ones (65% vs 20%). Based on the demographic data and results of RFLP, it appears that recent transmissions of TB from old patients have occurred in Tehran. However, drug-resistant TB in the city is mainly caused by strains that look different from those cultured from such patients. The majority of MDR isolates (85%) in this study contained a low copy number of IS6110 and PGRS in RFLP, and were mostly recovered from immigrants and refugees.